Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.144.136

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.144.77

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.144.111

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

This paper describes an improved process for controlling the initial deflection structure of cantilever‐type MEMS tactile sensors. By using residual stress, deposition sequence, and metal layer patterns, the initial deflection of the cantilever was successfully aligned to the same initial deflection with micron accuracy and 97% yield in a simpler and easier process than previous processes. This enables a reduction in the number of processes and flexible control of deflection, which is expected to improve yield and shorten fabrication time. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

DOI： 10.1002/tee.23989

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.144.6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.144.2

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/sensors56945.2023.10325048

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.143.251

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Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/biosensors58001.2023.10281079

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Publishing type：Research paper (scientific journal)  

Parkinson's disease (PD) is characterized by dopaminergic cell loss and the formation of Lewy bodies, of which the main component is aggregated and fibrillized α -synuclein (aSyn). Recent studies suggested that ultratrace amounts of aSyn aggregates are also present in biofluid specimens, and they can serve as a biomarker for PD. Because aSyn has been shown to possess a prion-like property, we attempted to enhance the sensitivity and specificity of a cantilever microsensor to detect aSyn aggregates by exploiting the properties of self-templating assembly and lipid interaction on the surface of liposome-immobilized cantilever sensor. We found that the liposome-immobilized cantilever sensor was able to successfully detect aSyn fibrils at a very low concentration (100 pg/mL), and the addition of aSyn monomers, which were converted into fibrils in the presence of aSyn aggregates and further acted as a template for fibrillization, lowered the detection limit to 10 pg/mL. The sensitivity of this cantilever sensor was comparable to or slightly superior to that of enzyme-linked immunosorbent assay (ELISA). Moreover, the lag time for the detection of aSyn fibrils has been significantly reduced to 100-120 min, compared to the tens of hours needed in conventional ELISA, real-time quaking-induced conversion (RT-QuIC), and protein misfolding cyclic amplification (PMCA) assays. Finally, preliminary measurements of aSyn aggregates showed the possibilities of discriminating serum from PD and non-PD patients. The liposome-immobilized cantilever sensor could serve as a promising tool for the early or preclinical diagnosis of PD.

DOI： 10.1109/JSEN.2023.3272659

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/tee.23813

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Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

Thickness shear mode (TSM) resonators consisting of metal films and quartz plates are widely used for sensor applications such as film thickness monitoring, force sensors, and odor sensors. However, the current sensor geometry prevents further improvements in its sensitivity and stability. Thinning the plate is necessary for high sensitivity, and advanced fabrication technologies are required for their commercialization. The solution is to use a support substrate to increase the mechanical strength, which can guide the transmittance of the electric field. Herein, we report a TSM resonator bonded to a support substrate. An AT-cut quartz resonator with a floating electrode on the top side was bonded to the support substrate. Two excitation electrodes were placed under the substrate. The support substrates evaluated in this study included borosilicate glass, Z-cut quartz crystals, and AT-cut quartz crystal plates. The quartz crystal resonator (QCR) bonded to the AT-cut quartz crystal plate and positioned at 90° to the crystallographic x-axis shows an excellent temperature coefficient of frequency of −60 ± 14 ppb/°C for a temperature range 11–40 °C. The proposed method reduces temperature sensitivity to 1/4 or less compared to that without a substrate. Furthermore, the resonator could be used as a quartz crystal microbalance. The proposed method may inspire further high-frequency QCR-based biochemical chips or various sensor applications with TSM resonators.

DOI： 10.1063/5.0132804

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Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1109/SENSORS52175.2022.9967179

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/ecj.12369

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/ecj.12369

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press Ltd.  

We previously reported a microelectromechanical system tactile sensor with elastomer-embedded microcantilevers. The sensor enabled the gripping control of soft objects by a robotic hand and acquisition of the object surface texture data. However, sensitivity improvement for more precise control and better texture information acquisition is desired. Here, the cantilever size and the sensor’s strain-gauge arrangement were redesigned, resulting in a sensor with significantly improved sensitivity. In addition, we report the sensitivity dependence on the cantilever size.

DOI： 10.20965/jrm.2022.p0677

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.142.91

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.142.85

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/eej.23370

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/eej.23370

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/ecj.12352

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/ecj.12352

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.142.17

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/eej.23356

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/eej.23356

Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.141.343

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Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.141.279

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

A method for the contactless endpoint detection of gold etching using a quartz-based capacitive detector is reported herein. To design a microfabrication process, the etch rates of materials to be used must be determined to control the etch depth. However, the etch rate changes gradually when the etching solution is used repeatedly. An endpoint and/or etch rate detection method is required to ensure process repeatability in a manufacturing environment. This method should be contactless because the etchants for metals are typically highly corrosive. In this study, a 32 MHz quartz-crystal oscillator is used to detect changes in the concentration of specific ions. The developed method can detect nanometer-order thickness changes during gold etching.

DOI： 10.1109/Transducers50396.2021.9495749

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/ecj.12317

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/ecj.12317

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.141.103

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.140.349

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.140.272

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.140.251

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejsmas.140.228

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Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2020.2.0_1725

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

To facilitate the early diagnosis of Alzheimer's disease and mild cognitive impairment patients, we developed a cantilever-based microsensor that immobilized liposomes of various phospholipids to detect a trace amount of amyloid beta (A beta) protein, and investigated its aggregation and fibrillization on model cell membranes in human serum. Three species of liposomes composed of different phospholipids of 1,2-dipalmtoyl-sn-glycero-3-phosphocholine (DPPC), DPPC/phosphatidyl ethanolamine and 1,2-dipalmitoyl-sn-glycero-3-phosphorylglycerol having varied hydrophilic groups were applied, which showed different chronological interactions with A beta(1-40) protein and varied sensitivities of the cantilever sensor, depending on their specific electrostatic charged conditions, hydrophilicity, and membrane fluidity. 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) having short hydrophobic carbon chains confirmed to show a large interaction with A beta(1-40) and a high sensitivity. Furthermore, the incorporation of cholesterol into DMPC was effective to selectively detect A beta(1-40) in human serum, which effect was also checked by quartz crystal microbalance. Finally, A beta detection of 100-pM order was expected selectively in the serum by using the developed biosensor.

DOI： 10.1002/bit.27380

Web of Science

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/bit.27380

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press Ltd.  

In the study, we investigated a detection method of partial contact of an object owing to curved or uneven surface of the contact object by a tactile sensor. The sensor is developed using three microcantilevers embedded in a polydimethylsiloxane (PDMS) bump. First, three bumps were employed to place a bump for each cantilever. It was possible to detect a contact position because the resistance change in the strain gauge on the cantilever under each bump significantly depended on the contact/non-contact state of each bump. Second, a tactile sensor with high-density arrangement of microcantilevers was used to detect partial or tilted contact situations. The results indicated that the output of a tactile sensor with high-density arrangement of microcantilevers reflected partial or tilted contact. It is suggested that a tactile sensor with multiple bumps and high-density microcantilevers allows for more dexterous gripping control based on the shape of the object and contact angle.

DOI： 10.20965/jrm.2020.p0297

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley-Liss Inc.  

In this study, we developed a detachable self-heated-stage suitable for high-speed processing of titanium by thermally assisted reactive ion etching (TRIE). The detachable self-heated stage was designed based on simulation results. The temperature of the stage increases rapidly within 10 minutes with low radio frequency (RF) power, because of the low thermal capacitance. The etch rates of titanium and titanium alloy by the TRIE improved compared with those of titanium and titanium alloy by a regular RIE. In addition, the replacement of the developed stage with another stage became easier than the previous stage.

DOI： 10.1002/ecj.12227

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

File： revisedmanuscript2.pdf

DOI： 10.1016/j.sna.2019.111774

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Publishing type：Research paper (international conference proceedings)  

We newly examined a self-templating effect of prionoid protein on a liposome-immobilized cantilever sensor in order to detect a trace amount of α-synuclein fibril as a biomarker molecule for Parkinson Disease. The developed sensor significantly decreased the detection threshold down to several hundreds of fM and its measuring time to a few hours, and could be applied in a clinical setting.

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Publishing type：Research paper (international conference proceedings)  

We have newly confirmed a selective detection of amyloid beta (Aβ) in human serum with its dynamic behavior by a strain gauge cantilever sensor immobilizing liposome incorporated with cholesterol. We examined the effect of incorporating cholesterol in the liposome in order to decrease the interaction between the liposomes and many proteins in human serum. The result implied that cholesterol suppress the interaction because of stabilizing effect in the lipid membrane [1]. Thus we concluded that we were able to detect Aβ, especially the state of its aggregation and fibrillization, in human serum by the cantilever sensor immobilizing liposome incorporated with cholesterol.

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

File： 電気学会論文誌-最終原稿.pdf

DOI： 10.1541/ieejsmas.139.375

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1541/ieejsmas.139.341

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Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1109/SENSORS43011.2019.8956615

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Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2019.2.0_2837

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1541/ieejsmas.139.169

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

We have developed cantilever-type MEMS tactile sensors with the PDMS elastomer that are sensitive to force and light, and shown that it can measure complex tactile senses. However, it is difficult for this sensor to detect correct response in liquid such as water or ethanol because of luck of resistances to these solutions. Therefore, we employ the fluoropolymer as the elastomer material instead of the PDMS in this work. Consequently, it is demonstrated that the tactile sensor with fluoropolymer can detect force and light successfully in water and ethanol in exactly as detection in air.

DOI： 10.1109/TRANSDUCERS.2019.8808646

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

File： 触覚センサによる多層柔軟物モデルの計測と有限要素解析-最終.pdf

DOI： 10.1541/ieejsmas.139.149

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Publishing type：Research paper (international conference proceedings)  

In this work, for the first time, chronological behavior of α-synuclein (aSyn) as causative agent for Parkinson Disease has been measured by phospholipid liposome-immobilized cantilever microsensor. Our goal is to detect aggregated, not a monomeric, forms of aSyn in its initial stage, as it is most toxic in patient's cerebrospinal fluid (CSF). The aSyn aggregates in phosphate buffered saline (PBS) were successfully detected compared to CSF of healthy person. With a developed temperature stabilization method at room temperature, which was stabilized within +/- 0.2/ °C, aSyn aggregation was detected down to 100 pM.

DOI： 10.1109/TRANSDUCERS.2019.8808657

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1541/ieejsmas.139.81

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Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2019.1.0_2531

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Language：English   Publishing type：Research paper (scientific journal)  

In this article, we developed a compact microdroplet monitoring sensor. This sensor is capacitive sensor combined a microfluidic circuit and a crystal oscillator. We succeeded in the generation and monitoring of microdroplets with this sensor. We optimized the sensing capacitor to improve the sensitivity of the sensor. With optimized the sensing capacitor, the frequency response can be increased. We measured NaCl aqueous solution concentration with the optimized sensing capacitor. From the measurement result, the high dynamic range measurement can be made by using two frequencies.

DOI： 10.1002/ecj.12128

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Serious flood disasters have escalated because of climate variation by global warming. For early alert of flood disasters, it is necessary to employ multipoint and wide-area water level monitoring throughout river basins, including headwaters. However, cost issue of the conventional sensing system has prohibited the progress of installation in small rivers. In this work, we propose the low-cost and contactless sensing system for water level in the river using a millimeter-wave radar and LPWA network. The prototype sensor can detect distance with average error rate of 2.56% and monitor water level in the actual river even during stormy weather. Furthermore, it is demonstrated that water level can be monitored by this sensor in various river conditions.

File： 電気学会論文誌 最終提出原稿.pdf

DOI： 10.1541/ieejsmas.138.461

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Language：Japanese   Publishing type：Research paper (scientific journal)  

In this paper, we developed a compact microdroplet monitoring sensor. This sensor is capacitive sensor combined a microfluidic circuit and a crystal oscillator. We succeeded in the generation and monitoring of microdroplets with this sensor. We optimized the sensing capacitor to improve the sensitivity of the sensor. With optimized the sensing capacitor, the frequency response can be increased. We measured NaCl aqueous solution concentration with the optimized sensing capacitor. From the measurement result, the high dynamic range measurement can be made by using two frequencies.

DOI： 10.1541/ieejsmas.138.382

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：John Wiley and Sons Inc.  

In this paper, we have demonstrated usefulness of the electromotive manipulator system with a developed single element MEMS sensor which can detect proximity, contact, and slipping to skillful gripping of the object. This MEMS sensor can detect proximity as impedance change of Si substrate by reflected light from the object due to the photoconductive effect. In addition, both normal and shear load can be also detected as resistance change of strain gage on cantilevers located threefold symmetry and embedded in polydimethylsiloxane (PDMS). By attaching the sensor on the electromotive manipulator, accurate control of gripping force was enabled by feedback of the sensor output.

DOI： 10.1002/eej.23098

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

In this paper, in order to perform delicate and advanced grip control like human, a proximity and tactile combination sensor using miniaturized microcantilevers one-fifth the size of previous one as the detection part was newly developed. Microcantilevers were arranged with higher spatial density than in previous works and an interdigitated array electrode to enhance light sensitivity was added. It is found that the interdigitated array electrode can detect light with 1.6 times higher sensitivity than that in previous works and the newly fabricated microcantilevers have enough sensitivity to applied normal and shear loads. Therefore, more accurate detection of proximity distance and spatial distribution of contact force become available for dexterous gripping control to prevent 'overshooting', 'force control error', and 'slipping'.

DOI： 10.3390/mi9060301

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

In this work, we have evaluated the planed surface of polyoxymethylene resin by light and strain sensitive MEMS tactile sensor. It is confirmed that the sensor output is correlated with surface profile and frictional characteristics of the resin. Additionally, it is demonstrated that difference of the surface color of the resin can be detected by this sensor.

File： 光・ひずみ複合触覚センサを用いたポリオキシメチレン樹脂の表面形状・色計測による質感評価　最終原稿.pdf

DOI： 10.1541/ieejsmas.138.250

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：M Y U Scientific Publishing Division  

Measurements of the surface texture of objects, including optical and tactile features, using a multimodal micro-electromechanical systems (MEMS) sensor are reported in this paper. The proposed MEMS sensor has two functions in its structure: light sensitivity of the MOS structure in the Si substrate and force sensitivity of the strain resistance gauge on microcantilevers embedded in the elastomer. Deflection of the cantilever, induced by an applied force, can be detected as a DC resistance change of the strain gauge film, which depends on the tactile texture including hardness, thickness, and surface roughness of the object. On the other hand, reflected light from the object, detected as AC impedance change at 5 MHz, depends on the color of the object. It is confirmed that the resistance and impedance changes correlate with the physical and optical properties of the object, respectively. Therefore, it has been demonstrated that the surface texture of the object, including optical and tactile features, can be characterized using a single MEMS sensor.

File： SS-1786-accepted.pdf

DOI： 10.18494/SAM.2018.1786

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：M Y U Scientific Publishing Division  

Quartz crystal microbalances (QCMs) have found applications as popular chemical and biological sensing tools. However, their current device geometry prevents their commercialization for industrial use. In this study, we propose a new disposable QCM sensor with an electrode only on the sensing side, making it suitable for sensor mounting. In this sensor system, the excitation electrode is positioned on a glass plate separate from the QCM. Such electrode configurations are suitable for sensor applications in flow cell systems in preference to common QCM systems because QCM mounting on the flow cell and the electrical interconnections between the QCM and the oscillation circuit are simple. The optimized configurations of the electrode diameter, separation distance, and orientation relative to the crystallographic x-axis of the plate are revealed for the first time. The proposed QCM can be applied to realize a disposable QCM-based biochip or hazardous gas sensor located inside a flow tube.

DOI： 10.18494/SAM.2018.1712

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley-Liss Inc.  

This paper describes development of self-heated stage suitable for thermal reactive ion etching (TRIE) of the functional metals. TRIE was evaluated using both experiments and simulations for etching functional metals. The self-heated stage was designed based on the simulation results. TRIE employs a self-heated stage which is thermally insulated aluminum plate as the etching stage of a regular RIE apparatus. The stage temperature increases rapidly within 10 min and etch rate does not depend on process time. TRIE technique was used to etch various kinds of functional metals: Ti, Mo, Ta, Nb, and Ti alloy (Ti-6Al-4V). It did improve the etching rate of these materials greatly.

DOI： 10.1002/ecj.12046

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

In this paper, we developed a contactless monitoring technique of liquid for measuring the concentration of liquid. This sensor is composed of dual sensing capacitors and quartz oscillation circuits. We succeeded in measuring dielectric and conductivity change at the same time by using dual frequency. Therefore, it can measure liquid tailored to its physicochemical properties with wide frequency range. In this study, we succeeded in monitoring change of concentration of cutting oil. The proposed sensor can be expected to be used for liquid monitoring.

DOI： 10.1541/ieejsmas.138.37

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Recent studies have proposed a model using the supervised neural-network (NN) as the haptic model. However, this model has the problem in expressing human tactile sense. Therefore, we constructed a haptic stage model based on the model of human-tactile sense and cognitive process. Our NN-based model consists of supervised and unsupervised stages. Using surface-scanning results from our trial micro-tactile sensor, we confirmed the material-identification problem with our model. A conventional full conventional NN(CNN) model achieved a 98.0% correct identification rate for 28 materials
our model achieved a rate of 67.2%. Our model employed typically is deepening because we used the convolutional process in all layers, therefore, we consider that our learning result lost local features on each material, and then identification rate was declined as result.

DOI： 10.1109/ICSENS.2017.8234173

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

This paper describes development of self-heated stage suitable for thermal reactive ion etching (TRIE) of the functional metals. Thermal reactive ion etching was evaluated using both experiments and simulations for etching functional metals. The self-heated stage was designed based on the simulation results. TRIE employs a self-heated stage which is thermally insulated aluminum plate as the etching stage of a regular RIE apparatus. The stage temperature increases rapidly within 10 min and etch rate is not depend on process time. TRIE technique was used to etch various kinds of functional metals: Ti, Mo, Ta, Nb, and Ti alloy (Ti-6Al-4V). It did improve the etching rate of these materials greatly.

DOI： 10.1541/ieejsmas.137.262

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

In this study, a thermally assisted reactive-ion etching (TRIE) technique using a 3D self-heated stage as the etching stage in a conventional reactive-ion etcher was developed and applied to a large size wafer. The 3D stage was designed based on simulation results and its heating characteristics on application of RF power were evaluated. Results indicated that the temperature of the etching stage increased rapidly to 350 °C, but maintained a distribution of ≤ 4 °C. Its application to various minor metals (Ti, Ti 6Al-4V, Ta, Nb, and Mo) was investigated. The resultant etch rates substantially increased with the use of the 3D self-heated cathode in a conventional reactive-ion etcher.

DOI： 10.1109/TRANSDUCERS.2017.7994289

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

In this paper, we have demonstrated usefulness of the electromotive manipulator system with a developed MEMS sensor to skillful gripping of various objects. This MEMS sensor is responsive to light with the photoconductive effect in Si and force with resistance change in the strain gauge layer on microcantilever structures, as a result, the sensor can detect both proximity and contact. In addition, since the cantilevers are located three-fold symmetry, the direction of applied force can also be detected. It is demonstrated that the proposed manipulator system with the developed sensor can grip not only rigid bodies but also gripping flexible objects.

DOI： 10.1109/TRANSDUCERS.2017.7994254

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

In this paper, we report that texture measurement of warm/cool and fluffiness sensations of various fabrics has been carried out by a multimodal MEMS sensor. This MEMS sensor can detect force as resistance change of strain gauge on micro-cantilever and light as impedance change of Si layer by the photoconductive effect, respectively. The sensor can also detect a temperature drop by heat transfer from the sensor to the contact object as resistance change of the strain gauge and impedance change of Si. It is demonstrated that warm/cool and fluffiness sensations of fabrics can be evaluated by the measured results of the proposed MEMS sensor depending on temperature drop and contact force.

File： PID4721655.pdf

DOI： 10.1109/TRANSDUCERS.2017.7994058

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

In this paper, we proposed a miniature thermogravimetric analysis sensor by using quartz crystal microbalance. We optimized the heating electrode shape of the microheater-integrated QCM for measuring a component of the soil on Mars and physically adsorbed water content in the Martian dust. Then, we evaluated the heating properties of the QCM in vacuum environment. As a result, the temperature of the electrode heated up to 300°C. We found out the optimized QCM showed low power consumption and had superior heating properties.

DOI： 10.1541/ieejsmas.137.180

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

In this paper, we have demonstrated usefulness of the electromotive manipulator system with a developed single element MEMS sensor which can detect proximity, contact, and slipping to skillful gripping of the object. This MEMS sensor can detect proximity as impedance change of Si substrate by reflected light from the object due to the photoconductive effect. In addition, both normal and shear load can be also detected as resistance change of strain gauge on cantilevers located three-fold symmetry and embedded in PDMS. By attaching the sensor on the electromotive manipulator, accurate control of gripping force was enabled by feedback of the sensor output.

File： 07E_03.pdf

DOI： 10.1541/ieejsmas.137.212

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

In this paper, a simple fabrication method for a Gaussian-shaped quartz crystal resonator was developed based on the surface tension of the photoresist. First, the photoresist profile on a quartz wafer was changed to a lens shape by the photoresist reflow. By changing the viscocity of the photoresist with propylene glycol monomethyl ether acetate, the photoresist profile on the quartz wafer was adjusted to create a Gaussian shape. Finally, the Gaussian-shaped QCR was fabricated by transferring the shape onto the quartz wafer using a reactive ion etching. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.sna.2017.04.019

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

We have developed a single sensor which can detect proximity and multi-axial touch force for smart-manipulation control of delicate objects. In this work, a measurement technique with modulated probe light to reduce of the environmental noise for proximity sensing has been reported. The white LED as probe light was switched at 150 Hz. Although the sensor output includes environmental noise from power source and room light, it is demonstrated that the proximity distance can be distinguished as amplitude of frequency component at 150 Hz.

File： 05E_05.pdf

DOI： 10.1541/ieejsmas.137.146

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Accumulating evidence suggests that interaction between amyloid- (A) and cell membrane is crucial to the pathogenesis of Alzheimer's disease (AD), and thus an increasing understanding of the impact of membrane composition on A-membrane interaction becomes essential for the mechanism elucidation of A-membrane interaction and the early diagnosis of AD. In this work, electrically neutral phosphatidylcholine (PC) as the most major class of membrane phospholipids, including 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and A(1-40) as the most common amyloid protein were selected as the research subjects, and a developed cantilever-based biosensor, on which liposomes comprised of PC lipids were immobilized, was applied to characterize in real time the interactions between A(1-40) and membranes comprised of PC lipids with different hydrophobic acyl chains, and to evaluate the effect of cholesterol incorporated in membrane on A-membrane interaction during the whole process of A(1-40) fibrillization. The results illustrate that the interaction between A(1-40) and PC membrane can be divided into three stages, which are related to the change in molecular states of A. More importantly, it is found that membranes comprised of PC lipids with shorter saturated acyl chains show higher interaction ability with A(1-40), and the incorporation of cholesterol into PC bilayer can remarkably accelerate and strengthen A(1-40)-membrane interaction. These results confirm that hydrophobicity is the main driving force for the interactions between A(1-40) and PC membranes. In return, the above results enlightened us to apply the current micro-cantilever immobilized with cholesterol-containing DPPC liposomes to challenge the detection of low-concentration A(1-40). This time 50-nM A(1-40) in aqueous solution has been effectively detected, suggesting that this proposed detection technique would contribute to A detection and early diagnosis of AD in the future.

DOI： 10.1002/elan.201600416

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MYU, SCIENTIFIC PUBLISHING DIVISION  

In this study, thermally assisted reactive ion etching (TRIE) was evaluated by both experiments and simulations. TRIE employs a self-heated stage instead of the etching stage of a regular RIE apparatus. The self-heated stage was designed on the base of the simulation results, and its heating characteristics upon the application of radio frequency (RF) power were evaluated. The temperature of the stage increases rapidly within 10 min because of the low thermal capacitance of the stage. An etch rate of 0.6 mu m/min and an etch selectivity of about 30 were achieved for titanium etching with SF6 plasma. In addition, we also investigated the application of TRIE for various kinds of minor metals (Mo, Ta, Nb, and Ti alloy) for the first time and achieved higher etch rates and etch selectivities than those of regular reactive ion etching (RIE).

DOI： 10.18494/SAM.2017.1444

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MYU, SCIENTIFIC PUBLISHING DIVISION  

In this paper, we report on texture measurements for an object, including tactile, warm/cool, and light sensations using a multimodal micro-electromechanical systems (MEMS) sensor. This MEMS sensor can detect force as a resistance change of the strain gauge on a microcantilever and light as an impedance change of a Si layer by a photoconductive effect. The sensor, which was maintained near human body temperature using a heater, can also detect a temperature drop after heat transfer from the sensor to a contacted object as a resistance change of the strain gauge or an impedance change of the Si layer. In this work, three different materials (copper, acrylic, and wood) were chosen as the target objects for the measurement of surface texture, and they were characterized on the basis of the differences in sensor outputs in active sensing experiments (approaching and pressing of the sensor with a probe light) on the sensor surface. In the proximity process, the impedance change of the Si layer depends on the surface reflectivity of the objects. After the object is touched by the sensor surface, the impedance of the Si layer and the resistance of the strain gauge of the sensor increase with the change in temperature caused by heat transfer. Furthermore, the resistance of the strain gauge decreases with the deformation of the cantilever caused by the pressing force from each object. Therefore, it is demonstrated that surface texture including the mechanical, optical, and thermal characteristics of various materials can be evaluated by active sensing using the proposed MEMS multimodal sensor.

File： SS-1443-galley proof.pdf

DOI： 10.18494/SAM.2017.1443

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

Insulator and piezoelectric thin films were deposited on titanium substrate, and characterized for application in tough MEMS tactile sensors. The titanium substrate was polished by buffing before the deposition of the thin films. An Al2O3 thin film was deposited as an insulator and showed good insulation characteristics on the polished titanium substrate. Piezoelectric BiFeO3 thin films were prepared by RF sputtering. The XRD pattern of the BiFeO3 thin film on the titanium substrate shows the presence of the ferroelectric phase. The polarization-electric field curve also shows a ferroelectric hysteresis loop. The results show that insulator and piezoelectric thin film can be formed on titanium substrate.

File： 01E_06_L.pdf

DOI： 10.1541/ieejsmas.137.46

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>This paper reports the development of wirelessly excited multi-channel QCM sensor for odor sensor applications. In this sensor, the excitation electrodes are positioned on a glass plate separate from the QCM. Such electrode configurations are suitable for odor sensor applications because the electrical interconnections between the QCM and the oscillation circuit are simple. We evaluated the dependence of the resonance frequency on the crystallographic orientation. We found out two vibrational modes that depends on each modulus of elasticity and the frequency responses of each mode are linear for mass loading.</p>

DOI： 10.1299/jsmermd.2017.1A1-K11

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>In this Paper, we report output characterization of the proximity and tactile combination MEMS sensor for controlling manipulation of flexible objects. This sensor can detect proximity by the internal photoelectric effect in Si substrate and normal and shear loads as tactile information are detectable by deflection of cantilevers, which are fabricated on the substrate surface and embedded in the silicone elastomer. The proximity and tactile outputs from this sensor attached on the electromotive actuator depend on distance to the target object and normal load applied by gripping the object, respectively. Furthermore, sensor output with shear load applied by weight of gripped flexible object is measured and the improved control method for stable gripping control of flexible objects is discussed.</p>

DOI： 10.1299/jsmermd.2017.1A1-N02

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The dynamic behavior of amyloid-beta protein (A beta) fibrillization on cell membrane is closely related to the progression of Alzheimers disease (AD). In this paper, we reports a new approach for real-time monitoring of the fibrillization process of A beta on lipid membrane using a miniaturized cantilever-based liposome biosensor, which contributes to the technology development of A beta label-free detection and the mechanism elucidation of A beta fibrillization on cell membrane. 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposome as model cell membrane was immobilized on the cantilever surface and A beta(140) was selected as a target protein in this work. Liposome-A beta interaction is evaluated by detecting the resistance change rate of the strain gauge embedded in the cantilever, which is directly proportional to the deflection of cantilever. 24-h real-time monitoring result clearly shows chronological change in the resistance with the progress of A beta fibrillization on liposomes. Moreover, it is found that the extent of liposome-A beta interaction is closely dependent on the aggregate state and concentration of A beta but is less dependent on the type of used solvent (water or serum). It is indicated that DPPC liposome shows sufficient affinity and selectivity to A beta even in serum. In particular, a concentration of A beta as low as 1 mu M can be detected using the cantilever-based liposome biosensor. Furthermore, it is confirmed that this biosensor has a potential of recognizing different states of A beta. We expect that the cantilever-based liposome biosensor becomes an effective tool for accelerating amyloid related research and developing the early diagnosis approach of AD. (C) 2016 Elsevier B.V. All rights reserved.

File： Characterization of Aβ Fibrillization.pdf

DOI： 10.1016/j.snb.2016.03.025

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

In this paper, we report the optimized combo sensor using quartz crystal resonator for analyzing the physicochemical properties of liquids. This sensor can measure the mechanical properties and the electrical properties simultaneously by integrating a LFE (Lateral Field Excited) sensor with an ACR (Antiparallel Coupled Resonator) or two types of ACR sensor on a same substrate. We optimized the electrode diameter of resonator for measuring a glucose aqueous solution or NaCl aqueous solution. Moreover, we measured concentration of glucose aqueous solution and NaCl aqueous solution with optimized sensor. This sensor is expected to be used for product quality control in industrial plants.

DOI： 10.1541/ieejsmas.136.343

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

In this paper, the liquid concentration sensor using crystal oscillator circuit which is available for measuring microdroplet is reported. We optimized the design of the sensing capacitor (SC) for sensing microdroplet. An electric-field-concentrated SC was used for measuring the liquid. The SC incorporated into the quartz oscillator has high-sensitivity because of the high stable crystal oscillator circuit. The SC is embedded in a silicone rubber. A spatially confined electric field is generated over the rubber. Therefore, the frequency of the oscillator changes by the contact with a liquid to the rubber. Moreover, the change less affected by a quantity of liquid. Because the frequency changes relate to the electrical characteristics of the liquid, the concentration of the liquid can be measured by the sensor. This sensor is expected to be applied to factory automation.

DOI： 10.1541/ieejsmas.136.319

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

A multifunctional tactile sensor which can detect approximation, contact, slipping, and surface texture of the target has been developed. The sensor is composed of multiple MEMS cantilevers fabricated on Si substrate embedded in PDMS, and can detect normal and shear forces. By indenting and sliding the sensor on the object surface, output depending on hardness, friction, and roughness, etc. can be obtained. Moreover, a function for detection of proximity was integrated monolithically through photo-sensitivity of Si substrate.

File： INEC2014sohgawa-final.pdf

DOI： 10.1109/INEC.2014.7460417

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MYU, SCIENTIFIC PUBLISHING DIVISION  

In this paper, a contactless sensor for the measurement of liquid concentration using a quartz oscillator is reported. An out-of-plane electric field distribution from a planar sensing capacitor (SC) is used for the noncontact sensor measurement of liquid concentration on a spacer. This sensor measures the changes in the capacitance of the SC by the changes in the frequency of the quartz oscillator. Because the capacitance is dependent on the relative permittivity and conductivity of the liquid sample on the spacer, it is pOssible to measure the concentration of the sample. The response is very stable because, in this sensor, the SC is incorporated into the quartz oscillator. Because the SC is in contact with the liquid sample instead of the quartz crystal resonator, the sensor has a high quality factor (approximately 30000). Moreover, this sensor can be used with a general integrated circuit (IC) and an electronic component at a low cost. The sensor is used for the noncontact measurements of liquid concentration.

DOI： 10.18494/SAM.2016.1262

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

We have newly evaluated the interaction of lipid membrane with two different proteins of lysozyme and carbonic anhydrase from bovine (CAB) using a micro cantilever-based liposome biosensor with a new droplet-sealing structure. Herein 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes are used as model lipid membrane and are immobilized on the surface of cantilever. The interaction of DPPC liposome with the target protein causes deflection of the micro-cantilever, which can stably be detected by measuring the resistance change of the strain gauge. The resistance change dependent on time is used to evaluate the characteristic of liposome-protein interaction. The resistance of the cantilever-based biosensor increases monotonously with time in both of the two protein solutions. Especially, chronological resistance change depends markedly on both the concentration and species of target proteins. Finally, these results lead us to conclude that the cantilever-based liposome biosensor with the droplet-sealing structure facilitates the characterization of protein-membrane interaction. It also means that this biosensor is a promising candidate device for label-free detection of concentration and species of different target proteins.

DOI： 10.1002/elan.201500412

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper reports mass sensitivity amplification in a Gaussian-shaped quartz crystal resonator (Gaussian-shaped QCR). To achieve amplification, a fabrication process for a Gaussian-shaped (not quasi-Gaussian) QCR was developed using photolithographic methods. Sensitivity amplification in the QCR was observed at the central portion. The mass response was three times higher than the theoretical value for gravimetric measurements of thin, uniform films. The optimized height of the shape, evaluated based on the Q factor, is higher than that of the convex shape. This resonator is expected to be applicable to mass measurement of various micro/nanoparticles.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this paper, we report texture measurement of the fabrics by a multimodal MEMS sensor. This sensor has sensitivity to both multi-axial force vector and light. Therefore, we can evaluate tactile texture by force measurement and visual texture by light measurement. This sensor has a possibility for texture measurement with both visual and tactile information in substitution for the human sensory test. In this work, various fabrics were chosen as the target object and evaluated by sensory test method using 10 test subjects. The dependences of the sensor output on reflection of probe light, reactive force, and frictional force by active approaching and touching of the sensor to the object surface were also evaluated. As a result, it is demonstrated that there is a good correlation between the results of the human sensory test and features of visual and tactile sensor output.

File： Evaluation Method of Fabrics by Visual and Tactile Texture Information using MEMS Combo Sensor 最終版.pdf

DOI： 10.1109/ICSENS.2016.7808624

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

We improved the sensitivity of NiCr strain gauge cantilever immobilized with liposome to detect A beta protein with low concentration. In this work, by immobilizing liposome incorporated cholesterol on cantilever, we could detect 50-nM A beta(1-40). Also, to investigate whether the hydrophobic carbon number of acyl chains of hydrophobic group influences A beta-membrane interaction, DMPC, DPPC, and DSPC liposomes were immobilized, respectively, on the cantilever surface. The results show that DMPC-A beta interaction is much larger than DPPC-A beta and DSPC-A beta interactions. We expect that the cantilever microsensor can apply to detect the A beta(1-40) protein in patients of Alzheimer's disease (AD) and also Mild Cognitive Impairment (MCI).

DOI： 10.1109/ICSENS.2016.7808468

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

A micro-cantilever with thermally stable strain gauge of a NiCr thin film and a self-assembled monolayer was fabricated by surface micromachining. Liposomes, as biosensing molecules, were immobilized on its surface. To prevent evaporation of the water solvent, a reservoir made of polydimethylsiloxane around the micro-cantilever was fabricated and covered with a glass plate. The resistance of the strain gauge increases with time in the amyloid beta (A beta) solution, because the cantilever is bent downward caused by interaction between A beta and liposomes immobilized on the micro-cantilever surface. Moreover, resistance change depends on the interaction ability of A beta proteins with liposomes. It is therefore indicated that the fabricated static mode micro-cantilever sensor with immobilized liposomes can be used to detect A beta proteins.

File： JSEN2470108.pdf

DOI： 10.1109/JSEN.2015.2470108

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

In this paper, we report the non-contact sensor for measurement of liquid concentration based on quartz oscillator. The non-contact sensing can be realized by using a leaked electric field of a planer sensing capacitor for sensing liquid on a spacer. This sensor measures capacitance changes of the sensing capacitor (SC) as frequency changes of the quartz oscillator. Since the capacitance is dependent on relative permittivity or conductivity of liquid on the spacer, it is possible to measure the concentration of them. The response is very stable because this sensor is incorporated the SC into the quartz oscillator. Because the SC is in contact with the sensing liquid instead of the quartz crystal resonator, the proposed sensor has a high quality factor (about 30,000). Moreover, this sensor can be used with general IC and electronic component, which takes low cost. The proposed sensor is expected to use for non-contact measurements of liquid concentration.

DOI： 10.1541/ieejsmas.135.210

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

We have developed the tactile sensor using micro-cantilevers embedded in the elastomer which can measure both the normal and shear forces by piezoresistance. In this work, a piezoelectric tactile sensor using micro-cantilevers embedded in the elastomer has been proposed and fabricated for realizing lower power consumption than the conventional sensor using piezoresistor. The BiFeO&lt
inf&gt
3&lt
/inf&gt
thin film (thickness: 400 nm) deposited by rf sputtering at substrate temperature of 520°C and gas pressure of 0.6 Pa has a good piezoelectric property because output voltage of 300 mV is obtained for strain induced by vibration of the cantilever. Therefore, it is demonstrated that the BiFeO&lt
inf&gt
3&lt
/inf&gt
can be used to detect the micro-cantilever deflection by external force applied on the tactile sensor.

File： 05E_02_3.pdf

DOI： 10.1541/ieejsmas.135.158

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

In this work, the thermal reactive ion etching (TRIE) technique for etching hard-to-etch materials is presented. The TRIE technique employs a self-heated cathode and a thermally insulated aluminum plate is placed on the cathode of a regular reactive ion etching (RIE) system. By optimizing the beam size to support the sample stage, the temperature of the stage can be increased to a desired temperature without a cathode heater. The technique was used to etch a bulk titanium plate. An etch rate of 0.6 mu m/min and an etch selectivity to nickel of 100 were achieved with SF6 plasma. The proposed technique makes a regular RIE system a more powerful etcher without the use of chlorine gas, a cathode heater, and an inductively coupled plasma source. (C) 2015 AIP Publishing LLC.

DOI： 10.1063/1.4917193

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

In this work, we present a new design involving a microheater-integrated quartz crystal microbalance (QCM) array for thermal desorption spectroscopy. Each QCM consists of two electrodes to excite thickness-shear-mode (TSM) vibrations on the crystal back side and one microheater to increase the temperature on the crystal front side. The resonance frequency was stable when a voltage was applied to the microheater. Carbon microparticles were coated on one of the QCMs for gas adsorption, and its frequency change during the temperature increase was calculated by subtracting the frequency change of an untreated QCM. The proposed QCM array was employed to separate ethanol from methanol. The separation was successful, as confirmed via thermal desorption spectra calculated by differentiating the resonance frequency change with respect to time.

DOI： 10.1541/ieejsmas.135.112

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this paper, a noncontact sensor for the measurement of liquid concentration using a quartz oscillator is reported. An out-of-plane electric field with a planer sensing capacitor (SC) is used for sensing a liquid on a spacer. This sensor measures the changes in the capacitance of the SC as the changes in the frequency of the quartz oscillator. The capacitance is dependent on the relative permittivity and the conductivity of the liquid sample on the spacer. Therefore, it is possible to measure the concentration of the sample. The response is very stable because in this sensor, the SC is incorporated into the quartz oscillator. Because the quartz crystal resonator is not contact with liquid, the proposed sensor has a high quality factor (approximately 30,000). Moreover, this sensor can be used with a general IC and an electronic component, with a low cost. The proposed sensor can be expected to be used for various kinds of liquid sensing applications.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Lead-free BiFeO3 thin films for tactile sensor using microcantilevers have been prepared on Pt and SrRuO3/Pt thin films on a SiO2 /Si substrate by RF sputtering, and the electrical characteristics have been optimized by controlling the substrate temperature, gas pressure, and oxygen partial pressure in deposition process. The BiFeO3 thin film (thickness: 300 nm) deposited on SrRuO3 (thickness: 80 nm) deposited at substrate temperature of 500 degrees C in gas pressure of 0.6 Pa and oxygen partial pressure of 0.24 Pa has good crystallinity, ferroelectricity, and piezoelectric property. Therefore, it is demonstrated that BiFeO3 thin film can be a good sensing material as a detection part of tactile sensor. Furthermore, a cantilever structure with piezoelectric capacitor and strain gauge has been fabricated and different time-dependent outputs from them can be obtained.

File： IEEE-paper-final-sohgawaconverttoPDF.pdf

DOI： 10.1109/ICSENS.2015.7370483

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

The tactile and visual texture measurement by multimodal MEMS sensor is reported. This MEMS sensor has two function in a structure: force-sensitivity of resistance of microcantilevers embedded in the elastomer and light-sensitivity of a MOS structure on the Si substrate. Deflection of the cantilever induced by applied force depends on the tactile texture including hardness, thickness, and roughness of the object, and is detected as DC resistance change of the strain gauge film. On the other hand, incident light depends on the visual texture of the object, and is detected as AC impedance change at 5 MHz. It is confirmed that the resistance and impedance changes depend on the physical and optical properties of the object, respectively. Therefore, it has been demonstrated that multimodal texture can be characterized by a single MEMS sensor.

File： PID3845957.pdf

DOI： 10.1109/ICSENS.2015.7370352

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

A multimodal sensor with Si micro-cantilever embedded in PDMS elastomer for measurement of proximity and touch forces has been fabricated and characterized. DC resistance of the strain gauge on the cantilever changes in proportion to the indentation depth of the object. On the other hand, the AC (&gt
0:5 MHz) impedance including photo-sensitive component of Si increases with increase of distance between the sensor surface and the object because of decrease of light intensity reflected on the object surface. Moreover, the AC impedance is different between grounding and floating of the proximate object because of difference of distribution of electrostatic field between electrodes, so that it is suggested that proximity can be detected as the impedance change by light as well as the electric field.

File： PID3327207.pdf

DOI： 10.1109/ICSENS.2014.6985362

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

The surface texture of various materials has been characterized by tactile sensor with a micro-cantilever embedded in the PDMS elastomer. The maximum output (resistance of strain gauge on the cantilever) change of the sensor by indentation of the object on the sensor surface depends on the hardness or thickness of the object. Moreover, output change is asymmetric in a back-and-forth indentation test because of relaxation of deformation. On the other hand, the output increases rapidly at beginning of stepwise sliding of the sensor at the object surface because of static friction, and changes periodically corresponding to stick-slip oscillation or surface roughness after slipping. It is demonstrated that about 30 materials of papers, clothes, leathers, and plastic sheets, have been classified into 5 clusters by the principal component analysis using feature quantities extracted from the sensor outputs.

File： PID3327209.pdf

DOI： 10.1109/ICSENS.2014.6985351

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

In this work, a new design for a microheater combined with a quartz crystal microbalance (QCM) array for thermogravimetric analysis is presented. Each QCM consists of two electrodes to excite thickness-shear-mode vibrations and one microheater to increase the temperature on the crystal backside. In addition, all the electrode pads are patterned on the crystal backside, making the design of the QCM compact and user-friendly. Finally, the proposed QCM array was employed to separate ethanol from methanol. This was successfully achieved via thermal desorption spectra calculated by differentiating the frequency changes. (C) 2014 AIP Publishing LLC.

File： Miniature quartz crystal-resonator-based thermogravimetric detector(著者校正).pdf

DOI： 10.1063/1.4894385

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

We have developed a micro-cantilever biosensor with embedded NiCr thin film strain gauge. Meanwhile, DPPC liposomes have been selected as sensing biomolecules to be immobilized on the surface of the micro-cantilever. The liposome-protein interaction was detected by measuring the resistance change rate of the strain gauge. In this work, a PDMS-based sealed reservoir structure was newly fabricated and added on the sensor to keep the target solution stable, where a long-time stable detection was achieved. The resistance of the cantilever-based biosensor increased with time in lysozyme or carbonic anhydrase from bovine (CAB) aqueous solution, and the characteristic of chronological resistance change varied with the concentration and kind of the proteins. It is expected that the micro-cantilever sensor with droplet-sealing structure can be used for bioassay of various proteins in future.

File： IEEE SENSORS 2014 PROCEEDINGS.pdf

DOI： 10.1109/ICSENS.2014.6984997

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

In this paper, we report the numerical calculation and experimental verification of a quartz-crystal-resonator-based methanol concentration sensor for fuel cell applications. This sensor is composed of a quartz crystal resonator (QCR) and an interdigital capacitor (IDC). Our sensor can detect a very small capacitance change with a resolution of sub fF. The fabricated sensor can measure a methanol concentration with a resolution of 0.008 wt%. In the present study, we found out optimized sensor design (QCR and IDC) for the substrate thickness and the range of the methanol concentration. By the use of this study, the capacitive sensor with higher resolution can be realized, and it can be expected to apply to various types of capacitive sensors. © 2014 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejsmas.134.224

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

A multifunctional tactile sensor which can detect approximation, contact, slipping, and surface texture of the target has been developed. The sensor is composed of multiple MEMS cantilevers fabricated on Si substrate embedded in PDMS, and can detect normal and shear forces. By indenting and sliding the sensor on the object surface, output depending on hardness, friction, and roughness, etc. can be obtained. Moreover, a function for detection of proximity was integrated monolithically through photo-sensitivity of Si substrate.

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A tactile sensing system that measures normal and shear (triaxial) forces has been developed, and its characteristics such as linearity and crosstalk have been evaluated. Triaxial forces are estimated from the resistance changes of NiCr thin film strain gauge attached to three microcantilevers. The output voltage of the Wheatstone bridge that comprises a gauge film and three reference resistances is acquired using an A/D converter after amplification. Triaxial forces are calculated from the output voltages of three microcantilevers by simple matrix multiplication. Nonlinearity and crosstalk are less than 4% when the normal force applied is up to 1N and less than 10% when the shear force applied is up to 0.2N. Active touch sensing was demonstrated using an object having a striped profile measuring 0.1mm in height and 1mm in width. © 2014 The Institute of Electrical Engineers of Japan.

File： IEEJ_Manuscript_proof.pdf

DOI： 10.1541/ieejsmas.134.58

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

In this paper, we report a micromachining of titanium using a desktop DRIE and fabrication of microstructure. We found out high speed exhaust characteristic is indispensable in the etching of titanium, and the etching rate more than 0.2 μm/min (a maximum rate is 0.4 μm/min) was provided in a small amount of etching gas (SF6). As the demonstration of the method, we fabricated microneedles imitating mosquito's proboscis. We revealed that it is available for fabricating precision microstructure. Titanium has excellent mechanical property and corrosion resistance, and it is expected to be used as a material for MEMS. In this method, it is expected to apply to fabricate the three-dimensional structures. © 2014 The Institute of Electrical Engineers of Japan.

File： 提出稿・デスクトップ型DRIE装置を用いたチタニウム微細加工.pdf

DOI： 10.1541/ieejsmas.134.96

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

A novel method has been proposed to detect proximity and tactile information using a single MEMS sensor. Tactile information is obtained from DC resistance change of NiCr strain gauge film. In contrast, proximity information is obtained from AC impedance change, which is caused by photo-absorption of Si wafer irradiated by a neighboring LED. Therefore, selection of the information to be acquired is performed by switching the DC and AC measurement system. Experimental results show almost linear tactile output to indentation of 0 to 0.5mm and non-linear proximity output to distance of 0 to 50 mm, respectively. Moreover, the sensor is able to acquire rough shape of a toroidal object by proximity measurement. © 2014 The Institute of Electrical Engineers of Japan.

File： Sensor-symp_IEEJ_final.pdf

DOI： 10.1541/ieejsmas.134.229

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A miniature tactile sensor has been fabricated by connecting stress-sensitive part with an amplifier of integrated circuit through through-silicon-via (TSV) electrically. The sensitive part consists of three warped cantilevers with piezoresistive NiCr thin film which are prepared on a silicon-oninsulator wafer by the surface micromachining technique. The TSV connection can reduce noise of detected change of the piezoresistive output induced by wire between the sensitive part and the amplifier. Fabricated tactile sensor of 5 μ 5mm2 size has linear dependence of the output on both normal and shear forces. The output noise has been successfully decreased by 14 and 34% in the sensor using the TSVs compared with that using wires of 3 and 6mm lengths, respectively. © 2013 The Japan Society of Applied Physics.

File： MN12071.pdf

DOI： 10.7567/JJAP.52.06GL08

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Polycrystalline BiFeO3 (BFO) films on Pt/TiO2/ SiO2/Si substrate have been prepared by a pulsed laser deposition (PLD) method with various repetition rates. The X-ray diffraction (XRD) pattern observes single-phase perovskite structure with a small secondary phase. While the film-thickness is increased with increasing repetition rates, the grain size increases, and the leakage current reduces. Also, good polarization versus electric field (P-E) hysteresis loops of all polycrystalline BFO films were obtained at room temperature (RT). It is seen that the polarization value (Pr) practically remains almost constant for all the BFO films, and the coercive field (Ec) decreases with increasing the film thickness. © 2013 Copyright Taylor and Francis Group, LLC.

DOI： 10.1080/00150193.2013.842064

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Epitaxial BiFeO3 (BFO) thin films have been prepared on La-doped (001) SrTiO3 substrates (La-STO) by using magnetic-field-assisted pulsed laser deposition. X-ray diffraction patterns of the epitaxial BFO thin films prepared under magnetic fields of 0, 0. 1, and 0. 4 T show only (00ℓ) diffraction peaks without secondary phases. From the results of reciprocal space mapping for all epitaxial BFO thin films, (003) reflections show splitting spots, and asymmetric spots of (-103) and (103) reflections exhibit a rhombohedral structure. The microstructure of the epitaxial thin films was modified by the strength of magnetic field, and a columnar structure was shown in the film prepared under a high deposition rate for a magnetic field of 0. 4 T. The polarization versus electric field hysteresis loops were obtained at room temperature (RT) in all the epitaxial films; in particular, the remanent polarization for the epitaxial film prepared under a magnetic field of 0. 1 T was 46 μC/cm2 at RT while the current density was reduced in comparison with those of other epitaxial films. © 2013 The Korean Physical Society.

DOI： 10.3938/jkps.62.1041

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Various kinds of papers have been identified by active touch of a multi-axial tactile sensor which has micro-cantilevers with strain gauge film on Si. When fine surface of the standard surface roughness scale and the printed stripe pattern on a banknote have been scanned by the tactile sensor, it allows to measure such fine roughness as a resistance change of the gauge film, and the triangular unevenness could be obtained down to 20 mu m. Transient responses of the resistance change have been obtained when the sensor was pushed and moved on various kinds of blank papers successively. Some features are extracted from the response by a principal component analysis and the papers are classified in four clusters.

File： Technical paper.Watanabe(Osaka.Univ.,Jpn).pdf

DOI： 10.1109/WHC.2013.6548398

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In this paper, we propose a single microheater combined quartz crystal microbalance array for thermal desorption spectroscopy. The each QCM has two electrodes for exciting thickness shear mode (TSM) vibrations on one side of the crystal and a double-spiral-shape heater on the other side. The resonance frequency is stable when a voltage was applied on the microheater. Carbon microparticles for gas adsorption were coated on one of the QCMs and the frequency change during temperature increase was extracted by subtracting the change of the other QCM. The proposed QCM array can monitor small mass changes at sub-ng level as a function of temperature. © 2013 IEEE.

DOI： 10.1109/Transducers.2013.6626745

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Language：Japanese   Publishing type：Research paper (scientific journal)  

A measurement method of surface texture of objects using active touching of a tactile sensor which has inclined micro-cantilevers with strain gauge film on Si has been reviewed. The fabricated tactile sensors have an ability of detecting roughness of more than ∼20 μm, and they can detect striped pattern on the Japanese banknote. Various kinds of blank paper which have different properties including hardness, friction coefficient, and surface roughness were identified using output from the fabricated tactile sensor. The feature quantities which depend on paper properties were defined from the resistance change by pushing, moving, and stopping of the sensor. The papers were classified in four clusters by principal component analysis of defined feature quantities. © 2013 The Institute of Electrical Engineers of Japan.

File： 電気学会論文誌投稿(レビュー)-ver13.pdf

DOI： 10.1541/ieejsmas.133.147

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Intensity and direction of normal and shear (3-axial) forces have been measured by using a tactile sensor with NiCr strain gauge film on 3 microcantilevers. Output voltage of the Wheatstone bridge which includes a gauge film is measured as digital signal after amplification. 3-axial forces are calculated from the output voltages of 3 microcantilevers every 100 ms. When normal force is applied from 0 to 1 N, the measurement errors of normal and shear forces are less than 50 mN and 10 mN, respectively. When shear force of 0.1 and 0.2 N is applied, the angle error of evaluated direction is less than 10 degrees.

File： IEEE_Sensors_Proc_yokoyama_final.pdf

DOI： 10.1109/ICSENS.2013.6688401

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We have fabricated the multi-axial tactile sensor which has micro-cantilevers with strain gauge film on Si embedded in hemispherical elastomer, and various kinds of papers have been identified by active touch. Transient responses of the resistance change have been obtained when the sensor was pushed and moved on various kinds of blank papers successively. Some features are extracted from the response by a principal component analysis and the papers are classified in several clusters. © 2013 IEEE.

File： 1274.watanabe.jpn.pdf

DOI： 10.1109/Transducers.2013.6626941

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A micro-cantilever with thermally stable strain gauge of a NiCr thin film and a self-assembled monolayer (SAM) was fabricated by surface micromachining and liposomes, as biosensing molecules, were immobilized on its surface. The resistance of the strain gauge increases with time in a biological protein (carbonic anhydrase from bovine: CAB) solution because the cantilever is bent downward by surface adsorption of CAB molecules. On the other hand, the resistance changes differently with the growth of another type protein, amyloid beta (A beta) fibrils. It is therefore demonstrated that the fabricated static mode micro-cantilever sensor can detect the interaction between the liposomes and the biological proteins.

File： PID2894703.pdf

DOI： 10.1109/ICSENS.2013.6688340

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A tactile sensor consisting of microcantilevers has been fabricated using the NiCr-thin-film strain gauge with low noise by surface micromachining and the slippage has been detected by using the fabricated tactile sensor array. The NiCr alloy thin film of Cr: 75 wt% has very low temperature coefficient of resistance (TCR) and is employed to suppress the temperature noise and drift. The fabricated tactile sensor with the NiCr thin film (Cr: 75 wt%) has linear dependencies of the resistance on normal and shear forces, and shows lower noise and temperature drift than that with conventional NiCr (Cr: 20 wt%) film. Normal and shear forces measured by fabricated sensor well coincide with applied forces with errors of 3-3.5 kPa. Moreover, the gripping status of the robotic hand was detected by using fabricated tactile sensor array, and the slipping condition can be judged at the rate of 76.5%. A (C) 2012 Elsevier B.V. All rights reserved.

File： sohgawa-rev-111201.pdf

DOI： 10.1016/j.sna.2011.12.055

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

Polycrystalline BiFeO3 (BFO) thin films have been prepared on Pt/TiO2/SiO2/Si substrates by using a pulsed laser deposition (PLD) method under a magnetic field. The X-ray diffraction (XRD) pattern shows a single-phase perovskite structure with no secondary phases, and (010) and (020) peaks slightly shift to lower angles in comparison with those of a BFO thin film prepared without a magnetic field. A columnar structure and small grain size were observed and the leakage current is slightly high in comparison with that of a BFO thin film prepared without a magnetic field. A polarization versus electric field (P–E) hysteresis loop was obtained at RT and the polarization at zero electric field is 50 µC/cm2. Ferroelectric domain switching corresponding to up and down polarization states was confirmed. An enhanced piezoelectric coefficient (d33) of about 100 pm/V has been obtained at a certain point. Ferroelectric and piezoelectric properties were affected by a columnar microstructure formed by magnetic field application.

DOI： 10.1143/JJAP.51.09MD05

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Polycrystalline BiFeO 3 (BFO) thin films have been prepared on Pt/TiO 2/SiO 2/Si substrates by using a pulsed laser deposition (PLD) method under a magnetic field. The X-ray diffraction (XRD) pattern shows a single-phase perovskite structure with no secondary phases, and (010) and (020) peaks slightly shift to lower angles in comparison with those of a BFO thin film prepared without a magnetic field. A columnar structure and small grain size were observed and the leakage current is slightly high in comparison with that of a BFO thin film prepared without a magnetic field. A polarization versus electric field (P-E) hysteresis loop was obtained at RT and the polarization at zero electric field is 50 μC/cm 2. Ferroelectric domain switching corresponding to up and down polarization states was confirmed. An enhanced piezoelectric coefficient (d 33) of about 100 pm/V has been obtained at a certain point. Ferroelectric and piezoelectric properties were affected by a columnar microstructure formed by magnetic field application. © 2012 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.51.09MD05

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File： 球・円柱表面形状を用いた動的表面テクスチャ計測多軸触覚センサ.pdf

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We have developed the tactile sensor using the microcantilevers with strain gauge film which can detect normal and shear forces simultaneously. In this work, the tactile sensor and the IC amplifier have been integrated heterogeneously to shorten the wire length by chip-on-chip stacking and reduce the noise in the output voltage. Standard deviation of the noise can be reduced from 27.6 mV to 3.3 mV by heterogeneous integration of the tactile sensor and the IC amplifier using Au wire bonding. By this heterogeneous integration, the device size and wiring numbers can be reduced, and installation of more sensors is allowed on fingertips of the robot. Moreover, through-silicon-via (TSV) holes were fabricated to mount an IC amplifier on the backside of the sensor chip, instead of using Au wires. Although TSV can be fabricated successfully, resistance to sacrificial etching process is problem. As a result, Si3N4 used instead of SiO2 has improved insulation between TSVs.

File： proceedings-sohgawa-rev-120530.pdf

DOI： 10.1557/opl.2012.1182

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Language：English   Publishing type：Research paper (international conference proceedings)  

We have developed the tactile sensor using the microcantilevers with strain gauge film which can detect normal and shear forces simultaneously. In this work, the tactile sensor and the IC amplifier have been integrated heterogeneously to shorten the wire length by chip-on-chip stacking and reduce the noise in the output voltage. Standard deviation of the noise can be reduced from 27.6 mV to 3.3 mV by heterogeneous integration of the tactile sensor and the IC amplifier using Au wire bonding. By this heterogeneous integration, the device size and wiring numbers can be reduced, and installation of more sensors is allowed on fingertips of the robot. Moreover, through-silicon-via (TSV) holes were fabricated to mount an IC amplifier on the backside of the sensor chip, instead of using Au wires. Although TSV can be fabricated successfully, resistance to sacrificial etching process is problem. As a result, Si 3N4 used instead of SiO2 has improved insulation between TSVs. © 2012 Materials Research Society.

DOI： 10.1557/opl.2012.1182

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Korean Institute of Electrical and Electronic Material Engineers  

Miniature ultrasonic and tactile sensors on Si substrate have been proposed, fabricated and characterized to detect objects for a dexterous robot. The ultrasonic sensor consists of piezoelectric PZT thin film on a Pt/Ti/SiO&lt
inf&gt
2&lt
/inf&gt
and/or Si diaphragm fabricated using a micromachining technique
the ultrasonic sensor detects the piezoelectric voltage as an ultrasonic wave. The sensitivity has been enhanced by improving the device structure, and the resonant frequency in the array sensor has been equalized. Position detection has been carried out by using a sensor array with high sensitivity and uniform resonant frequency. The tactile sensor consists of four or three warped cantilevers which have NiCr or Si:B piezoresistive layer for stress detection. Normal and shear stresses can be estimated by calculation using resistance changes of the piezoresitive layers on the cantilevers. Gripping state has been identified by using the tactile sensor which is installed on finger of a robot hand, and friction of objects has been measured by slipping the sensor. © 2012 KIEEME.

DOI： 10.4313/TEEM.2012.13.5.215

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BiFe0.9Co0.1O3 (BFCO) films have been prepared on Pt/TiO2/SiO2/Si substrates with a magnetic field of 0.4 T by pulsed laser deposition. BFCO films prepared under magnetic field show a single-phase perovskite structure with a little secondary phase, and their (010) and (020) peaks shift to lower angles than those of the film prepared without magnetic field. The BFCO film of about 1 µm thickness shows a columnar structure, although the BFCO film of about 350 nm prepared without magnetic field shows a grain like structure. The leakage current density of the BFCO film prepared under magnetic field is much lower than that of the BFCO film prepared without magnetic field. The saturated P–E hysteresis loops of both BFCO films are obtained at 80 K, and the M–H hysteresis loops of both BFCO films show a weak ferromagnetism behavior at room temperature.

DOI： 10.1143/JJAP.50.09NB03

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BiFe0.9Co0.1O3 (BFCO) films have been prepared on Pt/TiO2/SiO2/Si substrates with a magnetic field of 0.4 T by pulsed laser deposition. BFCO films prepared under magnetic field show a single-phase perovskite structure with a little secondary phase, and their (010) and (020) peaks shift to lower angles than those of the film prepared without magnetic field. The BFCO film of about 1 μm thickness shows a columnar structure, although the BFCO film of about 350nm prepared without magnetic field shows a grain like structure. The leakage current density of the BFCO film prepared under magnetic field is much lower than that of the BFCO film prepared without magnetic field. The saturated P-E hysteresis loops of both BFCO films are obtained at 80 K, and the M-H hysteresis loops of both BFCO films show a weak ferromagnetism behavior at room temperature. © 2011 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.50.09NB03

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File： NiCrゲージ薄膜の抵抗温度係数低減によるカンチレバー型触覚センサの高分解能化　提出用.pdf

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A tactile sensor array covered by a projected cylindrical elastomer has been designed and fabricated for crosstalk reduction among sensor elements caused by the lateral deformation of the elastomer. The analysis of elastomer deformation by the finite element method showed that the optimal thickness of the flat elastomer between cylinders and the substrate is 50-100μm, because the sensor structure has not only a low crosstalk but also a high robustness. A tactile sensor array having the flat elastomer of 70 μm thickness has little crosstalk and high robustness. © 2011 The Japan Society of Applied Physics.

File： MN10032.pdf

DOI： 10.1143/JJAP.50.06GM08

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

A Tactile sensor system consisting of elements with three microcantilevers embedded in a cylindrical elastomer has been fabricated by micro electromechanical systems (MEMS) technology. These sensor small size (3 x 4 mm(2)) chips are mounted on a flexible sheet, and thus the fabricated sensor array can be set even on a curved surface. In addition, the spacial distribution of normal and shear forces is obtained when two kinds of objects (an acrylic hemisphere and a brass cylinder) come in contact with the fabricated sensor shifted laterally. The distribution results appropriately reflect the surface shape of the object and give the behavior of the forces vector. (c) 2011 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.50.06GM02

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A Tactile sensor system consisting of elements with three microcantilevers embedded in a cylindrical elastomer has been fabricated by micro electromechanical systems (MEMS) technology. These sensor small size (3 × 4mm2) chips are mounted on a flexible sheet, and thus the fabricated sensor array can be set even on a curved surface. In addition, the spacial distribution of normal and shear forces is obtained when two kinds of objects (an acrylic hemisphere and a brass cylinder) come in contact with the fabricated sensor shifted laterally. The distribution results appropriately reflect the surface shape of the object and give the behavior of the forces vector. © 2011 The Japan Society of Applied Physics.

File： MN10112.pdf

DOI： 10.1143/JJAP.50.06GM02

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

A tactile sensor array covered by a projected cylindrical elastomer has been designed and fabricated for crosstalk reduction among sensor elements caused by the lateral deformation of the elastomer. The analysis of elastomer deformation by the finite element method showed that the optimal thickness of the flat elastomer between cylinders and the substrate is 50-100 mu m, because the sensor structure has not only a low crosstalk but also a high robustness. A tactile sensor array having the flat elastomer of 70 mu m thickness has little crosstalk and high robustness. (c) 2011 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.50.06GM08

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：計測自動制御学会  

We have designed and fabricated a tactile array sensors with three inclined micro-cantilevers embedded in elastomer, which can detect both normal and shear stresses. In this paper, we confirmed gripping status classification using sensor output. Using our sensor, four gripping status (free, grasping, holding and slipping) could be classified significantly.

DOI： 10.9746/sicetr.47.40

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Other Link： http://ci.nii.ac.jp/naid/10027787570

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER SCIENCE BV  

A tactile sensor has been fabricated using NiCr-thin-film strain gauge with low noise by surface micromachining and slippage has been detected by using the tactile sensor. NiCr alloy thin film of Cr: 75wt% has very low temperature coefficient of resistance (TCR) and is employed for suppressing the temperature noise and drift. The fabricated tactile sensor with NiCr thin film (Cr: 75wt%) has linear dependences of the resistance on normal and shear forces, and shows lower noise and temperature drift than that with conventional NiCr (Cr:20wt%). Normal and shear forces measured by fabricated sensor well coincide with applied forces with errors of 3-3.5 kPa. Moreover, detection of slippage between the robotic hand and an acrylic object was detected by using fabricated tactile sensor array, and slipping condition can be judged at the rate of 76.5%. (C) 2011 Published by Elsevier Ltd.

DOI： 10.1016/j.proeng.2011.12.156

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Ferroelectric Bi1:1Fe1-xCoxO3 (BFCO) thin films with x = 0-0:3 have been prepared on Pt/Ti/SiO2/Si substrates by chemical solution deposition (CSD) using iterative rapid thermal annealing (RTA) in nitrogen and oxygen. The crystallization of the rhombohedral structure of BiFeO3 (BFO) is observed clearly in all thin films, and a monoclinic Bi2O3 phase is also observed and is markedly larger in Co-doped BFO thin films than in BFO thin films. An electric field of 2MV/cm is applied to the Bi1.1Fe0.9Co0.1O 3 thin film annealed in nitrogen at 520 °C without dielectric breakdown, but its polarization versus electric field (P-E) hysteresis loops are not saturated owing to its high leakage current density. The Bi1.1 Fe0.8Co0.2O3 thin film prepared at 520 °C in oxygen shows a very good saturation of P-E hysteresis loops at room temperature (RT) at the low leakage current of about 8:7 × 10 -3A/cm2 under a high electric field of 1.5MV/cm. The leakage current at a low electric field may be Ohmic emission at any temperature
however at a high electric field, it may be attributed to tunnel emission at 80 K and Schottky emission at RT. © 2010 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.49.09MB05

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：一般社団法人映像情報メディア学会  

We have designed and fabricated a tactile sensors array with three inclined micro-cantilevers on a single sensor embedded in elastomer. Each sensor element can detect both normal and shear stresses. In this paper, we propose classification method of gripping status using sensor array and machine learning algorithm based on hidden marcov model. By integrating multiple sensor data using machine learning algorithm using hidden marcov model, our method allows to detect partial contact status such as non-contact, three types of partial contact, full-contact. Through experiments, we confirmed tha...

DOI： 10.11485/itetr.34.18.0_39

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Ferroelectric Bi1.1Fe1-xCoxO3 (BFCO) thin films with x = 0-0.3 have been prepared on Pt/Ti/SiO2/Si substrates by chemical solution deposition (CSD) using iterative rapid thermal annealing (RTA) in nitrogen and oxygen. The crystallization of the rhombohedral structure of BiFeO3 (BFO) is observed clearly in all thin films, and a monoclinic Bi2O3 phase is also observed and is markedly larger in Co-doped BFO thin films than in BFO thin films. An electric field of 2 MV/cm is applied to the Bi1.1Fe0.9Co0.1O3 thin film annealed in nitrogen at 520 degrees C without dielectric breakdown, but its polarization versus electric field (P-E) hysteresis loops are not saturated owing to its high leakage current density. The Bi1.1Fe0.8Co0.2O3 thin film prepared at 520 degrees C in oxygen shows a very good saturation of P-E hysteresis loops at room temperature (RT) at the low leakage current of about 8.7 x 10(-3) A/cm(2) under a high electric field of 1.5 MV/cm. The leakage current at a low electric field may be Ohmic emission at any temperature; however at a high electric field, it may be attributed to tunnel emission at 80 K and Schottky emission at RT. (C) 2010 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.49.09MB05

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Tactile array sensors with three inclined micro-cantilevers embedded in elastomer, which can detect both normal and shear forces, have been designed and fabricated. The inclined cantilevers consist of multilayer of Polymer/NiCr/SiN/Si and the normal and shear forces are detected as resistance change of NiCr thin film induced by deformation of the cantilever. This tactile sensor has sensitivity linear to normal and shear forces. Moreover, this sensor can detect normal and shear force by the resistance changes of 3 cantilevers. © 2010 The Institute of Electrical Engineers of Japan.

File： E部門誌投稿論文rev100217.pdf

DOI： 10.1541/ieejsmas.130.223

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Language：English   Publisher：The Japan Society of Mechanical Engineers  

We have designed and fabricated a tactile sensors array with three inclined micro-cantilevers on a single sensor embedded in elastomer. Each sensor element can detect both normal and shear stress. In this paper, we propose classification method of gripping status using sensor array and a machine learning algorithm. By integrating multiple sensor data using machine learning algorithm, our method allows to detect partial slipping on contact surface as an initial sign of slipping. Through experiments, we confirmed that our method achieves better classification ratio than existing methods using single sensor data.

DOI： 10.1299/jsmeicam.2010.5.351

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：一般社団法人電子情報通信学会  

Tactile array sensors with macro-cantilevers embedded in elastomer which can detect both normal and shear stresses have been designed and fabricated. Inclined cantilevers sensitive to normal and shear stresses can be obtained by using Cr/Si bilayer structure. These cantilevers can be successfully embedded in the elastomer without their destruction. The outputs from opposite cantilevers are same signs in the case of normal stress application, but the outputs are opposite signs in the case of shear stress. So, normal and shear stresses can be distinguished by summation and difference of outpu...

File： tecrep-sohgawa-rev.pdf

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Tactile sensor consisted of micro-cantilevers has been developed to detect both normal and shear stresses, and have human-friendly surface. NiCr thin film is used as strain gauge having low resistance drift, although Si piezo-resistance gauge shows the large resistance drift induced by large temperature coefficient of resistance (TCR) and its output is unstable. TCRs of NiCr films prepared by vacuum evaporation and sputtering (at RT and 600°C) are 0.054%, 0.082%, and 0.0065%, respectively, and are much lower than that of Si, 0.25%. As a result, reduction of resistance drift and stabilization of the sensor have been obtained by using NiCr thin gauge. © 2009 The Institute of Electrical Engineers of Japan.

File： 2008_main_page.pdf

DOI： 10.1541/ieejsmas.129.411

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Tactile array sensor of the micro-cantilevers embedded in the elastomer has been fabricated to detect normal and 2-axes shear stresses. It is demonstrated that tactile array sensor with 3 x 3 detective elements can be fabricated with excellent yield. The sensor element is sensitive to both normal and shear stresses applied on entire sensor surface. Moreover, it has good directional characteristics so that it is shown that magnitude and direction of shear stress can be obtained by difference of output voltages of adjacent sensor cantilevers. The sensor output has good reproducibility for multiple measurement. The output from sensor element drastically changes with shifting applying position of force. It is considered that we can obtain pressed position from distribution of output from sensor element array. ©2009 IEEE.

File： PID857986.pdf

DOI： 10.1109/SENSOR.2009.5285509

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File： PHS-08-13.pdf

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Cantilever-type tactile sensors of silicon-polymer beam structures were fabricated by surface micromachining and covering with elastomers. Two kinds of elastomers with different Young's modulus PDMS and urethane gel have been used to control deflection of the cantilevers and adjust the sensitivity cantilever-type tactile sensors. The resistance change of the sensor with PDMS has linear dependence on normal and shear stresses, but that of the sensor with urethane gel is nonliner to normal and shear stresses. However, the sensitivity of urethane gel type sensor is about 30 times larger than PDMS type sensor. © 2008 The Institute of Electrical Engineers of Japan.

File： IEEJ E paper temp2.pdf

DOI： 10.1541/ieejsmas.128.193

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MATERIALS RESEARCH SOC  

Tactile sensors of Si microcantilevers with a piezoresistive layer have been proposed for detection of both normal and shear stresses. Micro-cantilevers were fabricated by the surface micromachining of SOI wafers and were adequately inclined by controlling deflection with a Cr layer. The cantilevers were embedded in the PDMS elastomer to create a human-friendly surface. When a stress is applied to the surface of elastomer, the deformation of the cantilevers along with the elastomer is detected as a resistance change in the piezoresistive layer of the cantilevers. The piezoresistive response of the cantilever was analyzed by FEM calculations. The fabricated tactile sensor is sensitive to both normal and longitudinal shear stresses and its responses agree closely with the calculated value. Moreover, it has little sensitivity to shear stress in the transverse direction to the cantilever, which means that the tactile sensor can. distinguish the direction of shear stress. This sensor can be utilized for tactile sensing in human support robots.

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The tactile sensors for human support robots which can detect both normal stress and shear stress and have human-friendly surface have been proposed. Micro-cantilevers adequately inclined by Cr deflection control layer were fabricated by the surface micromachining on SOI wafer. The cantilevers were covered with the PDMS elastomer for human-friendly surface. When the stress is added to the surface of elastomer, the deformation of cantilevers along with elastomer is detected as piezoresistive layer in the cantilevers. The piezoresistive response of the cantilever is analyzed by FEM calculation. The response of the fabricated tactile sensor to normal stress and shear stress was measured by output from this resistance. The tactile sensor with PDMS elastomer can detect both normal stress and shear stress. On the other hand, it hardly has sensitivity to shear stress of orthogonal direction to the cantilever. It means that the tactile sensor can distinguish the direction of shear stress. The sensitivity of tactile sensor vary widely with cantilever pattern and relation between direction of cantilever and crystallite orientation of Si. It is suggested that the sensitivity of tactile sensor can be improved by using FEM estimation and selective ion implantation.

File： rad93B69.pdf

DOI： 10.1557/PROC-1052-DD04-07

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Silicon-fluoropolymer beam structures for cantilever-type tactile sensors have been fabricated and characterized. Curvature shape and tip height of fabricated cantilever agree well with theoretical calculated results. The deposition condition of polymer layer has been optimized in terms of process yield and tip height. The optimal thickness and curing temperature are 4-5 mu m and 200 degrees C for 1.5 mu m thick Si, respectively. The response of the tactile sensor with PDMS elastomer has been investigated against pressure. Although resistance of the platinum strain gauge has large temperature drift, it is obviously proportional to pressure, so that it becomes evident that the pressure can be detected by tactile sensor embedded in the elastomer.

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DOI： 10.1109/SENSOR.2007.4300420

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MATERIALS RESEARCH SOC  

Cr/Si bilayer cantilevers for an integrated multi-axis tactile sensor were fabricated by Si surface micromachining process. Among the cantilevers with various shapes, the rectangular and semicircular cantilevers were deflected upward with good controllability. The maximum deflections were compared with those calculated by the finite element method. Calculated deflections of Cr/Si cantilevers agree considerably with the experimental results. So, it is considered that the analysis by finite element method is useful to optimize layer thickness and size to obtain Cr/Si bilayer cantilevers with accurate deflection.

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The Cr/Si bilayer cantilevers for an integrated multi-axis tactile sensor were fabricated by Si surface micromachining process. Among the cantilevers with various shapes, the rectangular and semicircular cantilevers can be deflected upward with good controllability. The maximum deflections are compared with those calculated by finite element method. Calculated deflections of Cr/Si cantilever agree considerably with the measured one. So, it is considered that the analysis by finite element method is useful as optimization of layer thickness and size to obtain the Cr/Si bilayer cantilevers with accurate deflection.

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DOI： 10.1557/PROC-0969-W05-01

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Fixed oxide charges in HfO(2) thin films have been characterized by photoreflectance spectroscopy (PRS). HfO(2) films were deposited on Si by pulsed laser deposition (PLD) in N(2), O(2) and a Mixture of these gases. PRS spectral intensity decreases with increasing positive charge in a film. HfO(2) deposited in N(2) has larger positive charges than that deposited in O(2) because of smaller PRS spectral intensity of the former. It is confirmed by ArF laser irradiation that this positive charge is caused by oxygen defects in HfO(2). Moreover, the effects of rapid thermal annealing (RTA) on HfO(2)/Si have been evaluated by PRS. The PRS spectral intensity becomes maximum by RTA at 600 degrees C in N(2) or O(2) It is suggested that the suitable temperature for the RTA of the HfO(2)/Si structure prepared by PLD is 600 degrees C.

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DOI： 10.1143/JJAP.44.2409

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SrBi2Ta2O9 (SBT)/SiO2/Si structures have been characterized by photoreflectance spectroscopy (PRS) without electrode formation. SBT film was deposited on SiO2/n-Si by the metal-organic decomposition (MOD) method and annealed in O-2 atmosphere at 600degreesC. The voltage was applied by attaching ITO transparent electrodes during PRS measurement. The PRS spectral intensity of SBT/SiO2/Si structure has hysteresis characteristics as well as a C-V curve. Additionally, the spectral intensity gradually decreases with time, in a similar way to reduction of the capacitance. These results mean that the spectral intensity indicates the ferroelectricity of SBT film in SBT/SiO2/Si structure, so that it is considered that characterization of MFIS structure without electrode can be measured by PRS.

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SrBi2Ta2O9 (SBT)/SiO2/Si structures have been characterized by photoreflectance spectroscopy (PRS) without electrode formation. SBT film was deposited on SiO2/n-Si by the metal-organic decomposition (MOD) method and annealed in O2 atmosphere at 600 C. The voltage was applied by attaching ITO transparent electrodes during PRS measurement. The PRS spectral intensity of SBT/SiO2/Si structure has hysteresis characteristics as well as a C-V curve. Additionally, the spectral intensity gradually decreases with time, in a similar way to reduction of the capacitance. These results mean that the spectral intensity indicates the ferroelectricity of SBT film in SBT/SiO2/Si structure, so that it is considered that characterization of MFIS structure without electrode can be measured by PRS.

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DOI： 10.3938/jkps.46.262

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High-k HfO2 thin films have been prepared mainly at 400C in O2 atmosphere by pulsed laser deposition (PLD), and defects in the film have been characterized by electron spin resonance (ESR). Two ESR peaks are found at g ~ 2.003 and 2.006. The g ~ 2.006 peak intensity is higher in the sample deposited at target-sample distance of 45 mm than in that deposited at 60 mm. This is because part of the substrate and the film are exposed to high-energy particles ablated during deposition and are hence damaged. Moreover, the peak at g ~ 2.006 is related to the interface state density calculated from the high-frequency C-V curve. On the other hand, the peak at g ~ 2.003 is related to the thickness of the interfacial layer, and thus may be attributed to defects in the interfacial layer.

DOI： 10.3938/jkps.46.258

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High-k HfO2 thin films have been prepared mainly at 400degreesC in O-2 atmosphere by pulsed laser deposition (PLD), and defects in the film have been characterized by electron spin resonance (ESR). Two ESR peaks are found at 9 similar or equal to 2.003 and 2.006. The g similar or equal to 2.006 peak intensity is higher in the sample deposited at target-sample distance of 45 mm than in that deposited at 60 mm. This is because part of the substrate and the film are exposed to high-energy particles ablated during deposition and are hence damaged. Moreover, the peak at g similar or equal to 2.006 is related to the interface state density calculated from the high-frequency C - V curve. On the other hand, the peak at g similar or equal to 2.003 is related to the thickness of the interfacial layer, and thus may be attributed to defects in the interfacial layer.

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The fixed oxide charge in HfO_2 thin films have been characterized by photorenectance spectroscopj-.HfO_2 films were deposited on Si by pulsed laser deposition (PLD) in N_2, O_2 and mixture of these gases. The PRS spectral intensity decreases with increasing the positive charge in the film. HfO_2 deposited in N_2 has larger positive charge than that deposited in O_2, because PRS spectral intensity of the former is smaller than the latter. It is confirmed by ArF laser irradiation that this positive charge is caused by oxygen defects in HfO_2. Moreover, effects of rapid thermal annealing (RTA...

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Hf0_2 thin films have been prepared on Si(1OO) wafer by pulsed laser deposition (PLD) method, and characterized by electrical technique and ESR method. The peaks at g&amp;sime;2.006 and 2.003 are found in ESR spectra of Hf0_2 thin film deposited by PLD. The g&amp;sime;2.006 peak increased with decreasing gas pressure and the distance between target and substrate during deposition. This peak is considered to the defects from near the interface and is reduced because the energy of ablated particles is small when the distance between target and substrate is large and gas pressure is high. The g&amp;sime;2...

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SrBi2Ta2O9(SBT)/SiO2/n-Si stacked structures have been characterized by photoreflectance spectroscopy (PRS). The spectrum near E1 critical point energy is enhanced by deposition of SBT film. Annealing effect of the spectral intensity corresponds to that of (115) peak in XRD pattern of SBT film. Moreover, the PRS intensity increases when SBT film is poled by negative voltage. These spectral changes depend on the Si surface potential increase induced by remanent polarizations in the SBT film. The Si surface potential increase is 0.05 eV for -3 V poling. Critical point energy was estimated by peak positions of the PRS and large tensile stress is increased by the poling. It has been found that the spectral intensity closely corresponds to the ferroelectricity of the SBT film.

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DOI： 10.1080/00150190490452929

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HfO_2 thin films have been prepared on Si(100) wafer by pulsed laser deposition (PLD) method, and characterized by electrical and optical techniques. The samples were deposited at various temperature in O_2. From the results of I-V and C-V characteristics, the sample deposited at 400℃ at pressure of 0.2 Torr, shows relatively small interface state and fiat-band shift. Moreover, the sample is grown in O_2 and N_2 mixture ambient to reduce the interfacial layer. The film whose interfacial layer is relatively small is obtained, but an interface trap is increased. It needs to optimize the deposition conditions. Interface strain of Si and insulator is characterized by photoreflectance spectroscopy (PRS). PRS intensity increases with increasing growth temperature, and an interfacial layer increases with increasing growth temperature. The strain on the Si surface also increases. Moreover, PRS spectrum is not observed in the sample deposited at the O_2 pressure of 0.05 Torr. This suggests that the interfacial layer is small.

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High-k thin films of ZrO2, PrOx of similar to10 nm thickness have been prepared by pulsed laser deposition, and characterized in microscopic structure and electrical properties. Crystallization is promoted in ZrO2 films deposited above 400 degreesC, but a significant XRD peak was not observed in the ZrO2 film grown below 400 degreesC. The leakage current is decreased by increasing growth temperature, but all equivalent-oxide thickness (EOT) obtained from accumulation capacitance of C-V characteristics becomes large. The films deposited at 400 degreesC were annealed at 400 degreesC in O-2 gas to reduce the leakage. The leakage current change to be small, but the EOTs become large. Oxygen radical annealing is carried out to reduced the leakage, and is effective for ZrO2 thin film. Oil the other hand. only small improvement is observed ill the PrOx films.

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SrBi2Ta2O9(SBT) thin film grown on SiO2/Si by a pulsed laser deposition was evaluated by photoreflectance spectroscopy (PRS) which is one of the non-destructive techniques to characterize an interface. The stress of a SiO2/Si interface of ferroelectric-insulator-semiconductor (FIS) structure has been evaluated by using this method. As a result, there is a tensile stress which is larger than that before deposition, and the stress becomes large according to increasing SBT thickness. Moreover, when ferroelectric thin film is poled, the stress becomes small with increase of the voltage.

DOI： 10.3938/jkps.42.1072

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High-k thin films of ZrO2, PrOx of ~ 10 nm thickness have been prepared by pulsed laser deposition, and characterized in microscopic structure and electrical properties. Crystallization is promoted in ZrO2 films deposited above 400C, but a significant XRD peak was not observed in the ZrO2 film grown below 400C. The leakage current is decreased by increasing growth temperature, but an equivalent-oxide thickness (EOT) obtained from accumulation capacitance of CV characteristics becomes large. The films deposited at 400C were annealed at 400C in O2 gas to reduce the leakage. The leakage current change to be small, but the EOTs become large. Oxygen radical annealing is carried out to reduced the leakage, and is effective for ZrO2 thin film. On the other hand, only small improvement is observed in the PrOx films.

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DOI： 10.3938/jkps.42.1357

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SrBi2Ta2O9(SBT) thin film grown on SiO2/Si by a pulsed laser deposition was evaluated by photoreflectance spectroscopy (PRS) which is one of the non-destructive techniques to characterize an interface. The stress of a SiO2/Si interface of ferroelectric-insulator-semiconductor (FIS) structure has been evaluated by using this method. As a result, there is a tensile stress which is larger than that before deposition, and the stress becomes large according to increasing SBT thickness. Moreover, when ferroelectric thin film is poled, the stress becomes small with increase of the voltage.

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PrOx thin films have been prepared on Si(100) wafer by pulsed laser deposition (PLD) method, and characterized by electrical and optical techniques. The samples were deposited at 400℃ in O_2 at pressure of 0.2 Torr and post-annealed by RTA. Accumulate capacitance shown in C-V curve is increased by low-temperature and short-time annealing, but is decreased by high-temperature and long-time annealing. Moreover, interfacial layer is grown for high-temperature annealing for 60s. The fixed charge in the film is decreased by RTA at 400℃ for 20s and 60s, but interface trap is increased. Interface ...

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High-k thin films of ZrO2, HfO2 PrOx, of similar to10 nm thickness have been prepared by pulsed laser deposition (PLD), and characterized in microscopic structure and electrical properties. Crystallization is promoted in ZrO2 films deposited above 400degreesC, but a significant XRD peak was not observed in the ZrO2 film grown below 400degreesC. Moreover, density of the film is confirmed to saturate above 400degreesC by grazing incident angle X-ray reflectance. The leakage current is decreased by increasing growth temperature, but an equivalent-oxide thickness (EOT) obtained from accumulation capacitance of C - V characteristics becomes large. HfO2 films show the similar behaviors to ZrO2 films. The films deposited at 400degreesC were annealed at 400degreesC in O-2 gas to reduce the leakage, but the EOTs become large. So, these films were irradiated with oxygen radical at the pressure of 10(-3) Pa both to prevent the growth of interfacial layer and to enhance the oxidation of only the films. Although the leakage of ZrO2 films can be reduced by oxygen radical irradiation, only small improvement is observed in the PrOx films.

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PrO_x thin films have been prepared on Si(100)wafer by pulsed laser deposition method. It is shown from XPS spectra and TEM image of PrO_x film that the deposition in O_2 ambient of 0.2 Torr produces an interfacial silicate layer. Deposition in high vacuum at RT has only an ultra-thin interfacial layer, but both hysteresis in C-V characteristic and leakage current are large. After an O_2 annealing, the accumulation capacitance has increased, and the hysteresis and the leakage current have been improved, but the interfacial layer was grown. In deposition method using shadow mask, thin films ...

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We have prepared uniform ZrO_2 thin films for high-k gate dielectrics in the next generation ULSI ZrO_2 thin films have been grown on Si(100) wafer by pulsed laser deposition at 400℃. An uniform ZrO_2 thin film (of EOT=2.7 nm) is obtained. Oxygen radical annealing gives little change of EOT, and the leakage current is less than 1x10^&lt;-7 A/cm^2 at 1 MV/cm. Moreover, the interface between high-k material and Si has been characterized by photoreflectance spectroscopy. The stress on Si with ZrO_2 prepared by MOD, is smaller than the case of Si/SiO_2.

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Strain and stress at the Si surface have been studied by photoreflectance (PR) spectroscopy. A Si diaphragm structure has been fabricated in order to produce the surface strain caused by N-2 gas pressure which changes the PR spectra of the Si diaphragm. The transition energy obtained from the PR peak energy of approximately 3.4 eV is proportional to the surface stress, which is calculated by elastic analysis. Additionally, PR spectroscopy was applied to measure stress at the interface between the Si and thermal oxide. As the SiO2 growth temperature increases, the interface stress decreases. From our experimental results, it is considered that PR spectroscopy is effective as a contactless and nondestructive monitoring technique for Si surface stress.

DOI： 10.1143/JJAP.40.2844

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In this paper, we have prepared ZrO2 and lanthanide oxide thin films by PLD (Pulsed Laser Deposition) method and characterized these electrical properties by using C-V and J-V characteristics and these interfacial properties by using PR spectroscopy.

File： PROCEEDINGS-1.PDF

DOI： 10.1109/IWGI.2001.967576

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMERICAN VACUUM SOCIETY NORTHERN CALIFORNIA CHAPTER  

Thin gate oxide charging damage has been studied by photoreflectance (PR) spectroscopy in MOS structure samples. Antenna-area-dependent oxide charging damage such as the generation of SiO2/Si interface states as well as that of electron trap sites in the oxides, has been also addressed by the decrease of the PR peak signal intensity from MOS capacitors, and also confirmed by the capacitance-voltage (C-V) characteristics.

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Charging damage of metal/Si/SiO2 structure induced by the plasma exposure has been studied by the photoreflectace (PR) spectroscopy. The increase of the SiO2/Si interface states as well as that of the electron trap sites in the oxide is considered to be induced by the Ar plasma exposure. The interface states reduce the surface potential change and the signal intensity. The electron trapped in the oxide increase the surface potential and the signal intensity. The PR signal intensity decreases as the plasma exposure time increases. Therefore, the PR spectrum is considered to give primarily th...

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DOI： 10.11470/jsapmeeting.2020.1.0_2524

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DOI： 10.11413/nig.54.365

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DOI： 10.1541/ieejsmas.137.NL3_1

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：[科学情報出版]  

高齢化社会において増加する要介護者にとって、褥瘡はそのQOLを著しく低下させる疾病である。その予防のための皮膚へのストレスリスク評価のため、我々は接触時の多軸方向の荷重を評価できるマイクロメカニカルセンサを開発している。本稿では、その概要とともに、センサへの増幅回路集積や貫通電極配線の採用による電磁ノイズ低減について解説した。

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DOI： 10.1541/ieejsmas.136.NL2_1

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This paper reports the sensitivity of cantilever biosensor with liposome as sensing biomolecules im-mobilized on the cantilever surface is improved by incorporating cholesterol in phospholipid mem-brane of DPPC liposome. We especially investigate whether incorporating cholesterol in the mem-brane is effective to influence and improve the sensitivity for Aβ protein as a causative agent of Alzheimer&#039;s disease (AD). Consequently, the sensitivity of the cantilever sensor is significantly im-proved as 50-nM Aβ(1-40) has been detected by the incorporation of cholesterol. This result implies that the sensor has the possibility to detect Aβ(1-40) in plasma of AD patients.

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Language：English   Publisher：ELSEVIER SCIENCE BV  

We have previously developed a NiCr strain-gauge cantilever-based biosensor with liposomes as sensing biomolecules immobilized on the cantilever surface to investigate time course of dynamic behaviour of amyloid-beta (1-40) protein on lipid membrane [1]. In this work, we attempt to improve effectively the sensitivity of the cantilever sensor by incorporating liposome with cholesterol to enhance A beta-membrane interaction. Consequently, the sensitivity of the biosensor is significantly improved as 50-nM A beta(1-40) has been detected. This result shows the possibility of detecting A beta(1-40) in plasma of Alzheimer's disease (AD) patients because A beta concentration in the plasma of AD patients is reported to be in the range from 75 to 100 nM [2]. (C) 2016 The Authors. Published by Elsevier Ltd.

DOI： 10.1016/j.proeng.2016.11.526

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In this paper, we report the development of liquid concentration sensor using crystal oscillator circuit embedded in a robotic artificial skin. We optimized the shape of the sensing capacitor for sensing a small quantity of liquid locally. This sensor is composed of the sensing capacitor and quartz crystal resonator (QCR). The frequency of QCR changes by a liquid in contact with the artificial skin on the sensing capacitor. Because the frequency changes relate to the electrical characteristics (dielectric constant, conductivity) of the liquid, the sensor can measure the concentration of the liquid. This sensor is expected to be applied to a sensor embedded in the robotic artificial skin.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

In this paper, we report the texture quantitative measurement using the miniature multi-axial tactile sensor with microcantilevers which are fabricated by MEMS technology and embedded in the elastomer. The Si microcantilevers are deformed by both normal and shear forces and the deflection of the cantilever can be detected as resistance change of a strain gauge. The resistance changes by active-touching (pushing and sliding) to the object have been characterized and they are correlated with hardness, thickness, and roughness of the object. The first component obtained by principal component analysis of the correlation matrix among the resistance changes shows the surface texture characteristics (roughness, smoothness, friction) of the object. On the other hand, the second principal component shows texture characteristics including both bulky and elastic feelings of the object.

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DOI： 10.1541/ieejsmas.135.NL5_3

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© 15CBMS-0001. This paper reports a new approach for label-free detection of Alzheimer&#039;s disease (AD)-causative agent, namely amyloid-beta protein (Aβ). We selected Aβ(1-40) as a target for detection using a strain-gauge cantilever-based biosensor with liposomes as sensing biomolecules immobilized on the cantilever surface. The Aβ(1-40) proteins at different stages of fibrillization process were prepared and detected, respectively. The result shows that characteristic of chronological change of the gauge resistance depends on the aggregation state of Aβ(1-40). Then time course of dynamic behaviour of Aβ(1-40) on liposome was investigated. The result clearly exhibits the fibrillization process of Aβ(1-40) on lipid membrane.

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We have developed a strain-gauge cantilever-based biosensor with liposomes as model cell membrane immobilized on the cantilever surface to investigate time course of dynamic behavior of amyloid-beta (1-40) protein (A beta(1-40)) on lipid membrane. The results of this work clearly exhibit the characteristic of chronological change of the gauge resistance, which is closely related to the dependence of A beta-liposome interaction extent on the state of A beta during fibrillization and the type of lipid molecule. Therefore, it is considered that these results can adequately reflect the fibrillization process of A beta(1-40) on different kinds of lipid membranes. Meanwhile, it means that we are able to discriminate the molecular states of A beta and evaluate A beta fibrillization process using the cantilever-based liposome biosensor. (C) 2015 The Authors. Published by Elsevier Ltd.

DOI： 10.1016/j.proeng.2015.08.561

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