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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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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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

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

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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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

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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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

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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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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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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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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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：English   Publishing type：Research paper (scientific journal)  

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

DOI： 10.1016/j.sna.2019.111774

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

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：Japanese   Publishing type：Research paper (scientific journal)  

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

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

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Publisher：Elsevier {BV}  

DOI： 10.1016/j.electacta.2019.01.118

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

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

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

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

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

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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 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.

DOI： 10.1541/ieejsmas.138.250

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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 (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.

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 (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)  

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.

DOI： 10.1109/TRANSDUCERS.2017.7994058

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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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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Vacuum Society of Japan  

This paper describes the microfabrication of titanium micro molds for the microfluidic chip by a reactive ion etching (RIE) system. The etching was carried out using SF6 plasma.We have examined the etching rate and surface roughness at the range of process pressure 0.3-0.7 Pa and RF (13.56 MHz radio-frequency) power 30-70 W. The etching rate is over 0.3 mm/min at the RF power of 70W. The surface roughness of etched substrates is below 40 nm at the process pressure of 0.3 Pa. We made a titanium micro mold and molded microfluidic chips by using polycarbonate, and microresico® (Polypropylene resin).

DOI： 10.3131/jvsj2.60.145

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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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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.

DOI： 10.1541/ieejsmas.137.212

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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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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.

DOI： 10.1541/ieejsmas.137.146

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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 (scientific journal)   Publisher：Vacuum Society of Japan  

The etching characteristics of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA) bulk plates were studied in a magnetron enhanced reactive ion etching (M-RIE) system. The etch rates of the plates for oxygen plasma were investigated under the pressure range 0.1-2.0 Pa, and were found to strongly correlate with the self-bias voltage. The plates presented smooth surface in the 0.1-1.0 Pa pressure range, and rough surfaces at 1.5 Pa and 2.0 Pa. The roughness was introduced by a micromask sputtered from the chamber material. The titanium etching mask exhibited lower etch rates for oxygen plasma than aluminum and silicon dioxide. Finally, using the dry-etched titanium mask in low-pressure oxygen plasma, we fabricated a 5-μm pitch line-and-space structure on a PTFE plate and a 4-μm square pillar array on a PFA plate.

DOI： 10.3131/jvsj2.60.176

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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.

DOI： 10.1541/ieejsmas.137.46

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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.

DOI： 10.18494/SAM.2017.1443

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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：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

CiNii Article

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

DOI： 10.1109/ICSENS.2016.7808624

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

DOI： 10.1541/ieejsmas.136.343

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

DOI： 10.1541/ieejsmas.136.213

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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：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.2016.1179

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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：Japanese   Publisher：The Surface Science Society of Japan  

DOI： 10.14886/sssj2008.36.0_272

CiNii Article

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

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°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.

DOI： 10.1109/ICSENS.2015.7370483

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

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.

DOI： 10.1109/ICSENS.2015.7370352

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The 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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Other Link： https://jlc.jst.go.jp/DN/JLC/20011227951?from=CiNii

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

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 BiFeO3 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 BiFeO3 can be used to detect the micro-cantilever deflection by external force applied on the tactile sensor.

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

DOI： 10.1541/ieejsmas.135.90

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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  

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.

DOI： 10.1109/ICSENS.2014.6985362

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

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.

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.

DOI： 10.1063/1.4894385

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

In this paper, the development of a multi chemical sensing method using a single quartz crystal resonator and micro flow channel has been reported. In the developed device, samples pass through two capacitors that are mounted as sensing parts in a microchannel with a time lag. Connecting the capacitors to the single quartz crystal resonator, one can obtain frequency change Delta F of the resonator as time lag signals depending on the relative permittivity of samples. The optimization of resonator diameter was also carried out in this paper. Using the proposed method, we can realize multi chemical sensing with a single resonator.

DOI： 10.1109/JSEN.2013.2281099

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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.

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.

DOI： 10.1541/ieejsmas.134.229

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

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.

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 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：Japanese   Publisher：The Japan Society of Mechanical Engineers  

A multifunctional MEMS sensor for measurement of proximity and touch of an object has been fabricated and characterized. The DC resistance changes linearly to indentation distance of the object. On the other hand, the AC (> 500 kHz) impedance increases with increase of distance between the sensor surface and the object because of decrease of light intensity reflected on the object surface. An error of proximity measurement induced by environmental temperature and illuminance has been characterized. The error was estimated at 1 mm for 1℃ temperature change and at 2 mm for 500 lx illuminance change, respectively, and they are enough low in stable environment. Moreover, the AC impedance was different between grounding and floating the proximate object because of difference of distribution of electricstatic field between electrodes, so that it is suggested that proximity can be measured as the impedance change by light as well as electrostatic field.

DOI： 10.1299/jsmermd.2014._1p2-x09_1

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In this paper, we report the development of a monolithic methanol concentration sensor. An interdigital capacitor and a resonator are fabricated on a single-crystal substrate. The methanol concentration can be measured by measuring the frequency shift of the resonator because the shift corresponds to a change in the relative permittivity of the capacitor connected in series to the resonator. The quality factor (Q) of the sensor is more than 20,000 since the methanol solution is not in contact with the resonator but with the capacitor. The smallest resonator diameter and sensor size for achieving a resolution of 0.3 wt% were 1.5mm and 2.6 × 10.9 × 0.1mm3, respectively. Because the structure and manufacturing process are simple, the proposed sensor can be expected to be used for various kinds of liquid sensing applications. © 2013 The Japan Society of Applied Physics.

DOI： 10.7567/JJAP.52.127101

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

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°.

DOI： 10.1109/ICSENS.2013.6688401

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

In this study, we have proposed a low-pressure reactive ion etching of bulk polymer materials with a gas mixture of CF4 and O-2, and have achieved precise fabrication of poly(methyl methacrylate) (PMMA) and perfluoroalkoxy (PFA) bulk polymer plates with high-aspect-ratio and narrow gap array structures, such as, pillar, frustum, or cone, on a nano/micro scale. The effects of the etching conditions on the shape and size of each pillar were evaluated by changing etching duration and the size/material of etching mask. The fabricated PMMA array structures indicate possibilities of optical waveguide and nanofiber array. PFA cone array structures showed super-hydrophobicity without any chemical treatments. Also, polystyrene-coated silica spheres were used as an etching mask for the pillar array structure formation to control the gap between pillars. (c) 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

DOI： 10.1063/1.4830277

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Proton transport properties of a partially protonated poly(aspartic acid)/sodium polyaspartate (P-Asp) were investigated. A remarkable enhancement of proton conductivity has been achieved in the thin film. Proton conductivity of 60-nm-thick thin film prepared on MgO(100) substrate was 3.4 X 10(-3) S cm(-1) at 298 K. The electrical conductivity of the oriented thin film was 1 order of magnitude higher than the bulk specimen, and the activation energies for the proton conductivity were 0.34 eV for the oriented thin film and 0.65 eV for the pelletized sample, respectively. This enhancement of the proton transport is attributable to the highly oriented structure on MgO(100) substrate. This result proposes great potential for a new strategy to produce a highly proton-conductive material using the concept of an oriented thin film structure without strong acid groups.

DOI： 10.1021/la400412f

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

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.

DOI： 10.1109/Transducers.2013.6626745

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

This paper reports a fabrication method of high-Q, quartz-crystal resonator having deep etched structures with precisely modulated surface shape. The method to realize the structures bases on the use of multi-layered mask having different etch selectivity to quartz during deep reactive ion etching (DRIE) process. Here, hard mask (nickel) and soft mask (photoresist) was used for deep etching and modulating etched surface shape, respectively. Because of the large difference in the etch selectivity between quartz/hard-mask (&gt;30) and quartz/soft-mask (0.3-2), the limited range size of modulating shapes in the vertical direction was improved. Inverted-mesa quartz resonators combined with a spherical shape are demonstrated using the proposed method showing the improvement of the device performance. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.sna.2012.02.006

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

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

In this paper, the development of multi chemical sensing method using a single quartz resonator and micro flow channel has been reeported. In the developed device, samples pass through two capacitors mounted as sensing parts in a microchannnel with a time lag. Connecting the capacitors to thee single quartz resonator, one can obtain frequency change Delta F of the resonator as time lag signals depending on the relative permittivity of samples. Using the proposed method, we can realize multi chemical sensing with a single resonator.

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

This paper reports the development of monolithic methanol concentration sensor for direct methanol fuel cell (DMFC). An interdigital capacitor and a resonator are fabricated on a single quartz crystal substrate. Methanol concentration can be measured by the frequency change of the resonator because the change corresponds to the dielectric constant change of the capacitor connected in series to the resonator. The smallest diameter of resonator and size of sensor that achieve a resolution of 0.1 wt% were 1.5 mm and 2.6×10.9×0.1 mm, respectively. Because the structure and the manufacturing process are simple, we expect it will be used for various kinds of liquid sensor. © 2012 IEEE.

DOI： 10.1109/ICSENS.2012.6411072

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

In this work, metallic glass films (Zr-Cu-Al-Ni) were successfully deposited and patterned by sputter and reactive ion etching (RIE) technologies for widening micro electro mechanical system (MEMS) field. The amorphous structure of the deposited Zr-based alloy films were confirmed by X-ray Diffraction (XRD) and transmission electron microscopy (TEM). The home-made RIE equipment was used to dry etch the metallic glass films for patterning. This technique removes the atoms by ion bombardment. The different gases were selected during the RIE plasma etching process such as argon (Ar), octafluorocyclobutane (C4F8) and sulphur hexafluoride (SF6). Two kind photoresists, AZP4620 and OFPR800, were used as the etching masks for transferring the patterns to Zr-based metallic glass thin film. The etching rate and etching selectivity of photoresist and metallic glass were tested in different photoresist hard-baking conditions and different etching RF power. Besides, the condition of employing different working gases during RIE etching process was carried out and studied in this work. As a result, the metallic glass Zr-Cu-Al-Ni films were successfully structured with 20nm/min etching rate and 1:3.2 (metallic glass: photoresist) etching selectivity by using a mixture of Ar and C4F8 gases. This plasma etching technology realizes metallic glass films patterning for advanced MEMS devices fabrication. © 2012 IEEE.

DOI： 10.1109/ICSENS.2012.6411175

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

A dual quartz sensor has been developed which enables the analyses of physicochemical properties of liquids. In this sensor, an ACR (Antiparallel Coupled Resonator) type quartz sensor and a LFE (Lateral Field Excited) type quartz sensor were fabricated on a same plate. The ACR can measure frequency response caused by a mechanical characteristic (viscoelasticity) of liquids. The LFE can measure frequency response caused by both the mechanical characteristic and the electrical characteristics (conductivity and dielectric constant) of liquids. By subtracting the frequency shift of the LFE and the ACR, the dual quartz sensor is possible to calculate the electrical characteristics. Therefore the dual quartz sensor allowed simultaneous measurements of electrical characteristics and the mechanical characteristic of a liquid. © 2012 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejsmas.132.174

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

This paper reports the design and fabrication of a Gaussian-shaped AT-cut quartz crystal resonator. The thickness distribution of the resonator was designed following a Gaussian-type function. The distribution was based on the analysis of thickness shearing vibration calculated using finite element analysis for a flat-shaped resonator. The vibration analysis showed improvement of the energy trapping effect, and the vibration at the wafer edge was negligible. For the experimental verification, we attempted to fabricate a Gaussian-shaped resonator using microfabrication technologies. The resonant characteristics were substantially improved by the shaping. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.sna.2010.04.005

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

A monolithic quartz crystal microbalance (QCM) array fabricated with the excitation electrodes located on the airside and the gold conductive layer on the sensing side was evaluated as a biosensor array in a simple flow cell. The electrode configuration of the new QCM is suitable for sensor applications in flow-cell systems compared with standard QCM because the mounting of the QCM on the flow cell and the electric interconnection between the excitation electrode and oscillation circuit does not require considerable skill and effort. Frequency response to the adsorption of human IgG to anti-human IgG antibody at the concentrations of 0.1-100 mu g/ml was successfully measured, and the results showed that this new sensor can be an alternative to the standard QCM. In addition, the affinity difference between the reference QCM coated with bovine serum albumin for reducing nonspecific binding and the antibody-immobilized QCM to anti-human IgG antibody was simultaneously measured by using the monolithic QCM array within the flow cell. The monolithic QCM array designed for mounting on a flow cell will be expected to use for studying a surface science in a microchannel.

DOI： 10.1109/JSEN.2010.2051662

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

Lithium niobate (LN) etching has been demonstrated with an electron cyclotron resonance (ECR) plasma and low-frequency bias. The etching was studied by using Ar, BCl3 and SF6 gases. The etch rates of BCl3 and SF6 are about 3.8 and 4.6 times higher than that of Ar, respectively. The highest etch rate (220 nm/min) was obtained under the condition of SF6 plasma and 1 MHz bias. The etching method which can fabricate micro-trenches with high-aspect ratio and smooth surfaces has been achieved.

DOI： 10.3131/jvsj2.53.501

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

This paper reports a real-time measurement of photocatalytic reactions by using a miniaturized quartz-crystal microbalance (QCM) array. The QCM was miniaturized and integrated on the same quartz plate using microfabrication techniques. Two QCMs were located close to each other, with one of the QCMs used as a reference sensor for the accurate and independent determination of mass change effects and environmental change effects. The QCM output was compensated for frequency shifts induced by ultra violet (UV) irradiation by subtracting the frequency shift of the reference sensor. The minimum detectable frequency shift under the irradiation was within 1 Hz. The measured photodecomposition speed of methylene blue dye on a TiO(2)-coated QCM agreed well with that evaluated by the standard optical testing method under dry condition. The developed method enabled us to measure the photodecomposition of a surfactant on a TiO(2)-coated QCM with sub-nanogram mass resolution in real time.

DOI： 10.1088/0960-1317/19/9/094019

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

This paper reports integration of quartz-crystal microbalance (QCM) sensors on a monolithic quartz crystal plate without using microfabrication. The QCM sensor used for this study is specially developed for sensing within a microfluidic channel. In this study, the distance between QCMs was optimized by monitoring frequency change caused by a mass load onto a neighboring QCM. It was found that circular shape QCM is suitable for the integration. The optimized QCM array was used for monitoring an etching of a gold electrode of the QCM by electrochemically generated oxidant. The measured phenomenon is practically useful for the cleaning of an integrated sensor within a packaged microfluidic channel. © 2009 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejsmas.129.439

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

We report the construction of microfluidic biofuel cells connected in series by semiautomatic air valves, in which a lotus leaf-like superhydrophobic structure (a micropillar array) traps air and ionically isolates each biofuel cell aligned within the channel. The micropillar array was prepared by conventional photolithography and reactive ion etching (RIE) techniques, and the structural parameters of the micropillars (size and spacing) were optimized as to obtain the highest degree of hydrophobicity. The open-circuit voltage measured at the ends of three aligned biofuel cells was three times larger than that of a single cell using the semiautomatic air valve system. ©2009 IEEE.

DOI： 10.1109/SENSOR.2009.5285620

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Other Link： http://orcid.org/0000-0003-2566-4172

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

This paper presents the novel method to control polymer surface morphology using reactive ion etching (RIE) technique and its application to microfluidic devices. By using this method, polymer surface morphology could be controlled in the wide range between smooth surface and grassy surface with a newly developed electron cyclotron resonance (ECR)-RIE system. It was found that the polymer surface morphology is closely related to metal micromask concentration on the surface. Our system could easily control the micromask concentration only by changing the total pressure in the chamber. The etching characteristics of 75 mol% O-2-CF4 gas mixture were systematically investigated as a function of total pressure. The smoothest surface with the arithmetic mean roughness value (R-a) less than 10 nm was achieved at 0.1 Pa. On the other hand, the grassy surface with high aspect ratio of 80 was uniformly formed on the polymer surface under the higher-pressure range from 1.0 Pa to 1.5 Pa. Furthermore, the proposed method was applied to microfluidic channels with multiple pillars, and a hybrid structure with smooth and grassy surfaces. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2008.01.050

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We designed a new surface forces apparatus for measuring the interactions between two nontransparent substrates and/or in nontransparent liquids. The small displacement of a surface, the bottom one in this study, was measured by the two-beam (twin path) interferometry technique using the phase difference between the laser light reflected by the fixed mirror and that by the mirror on the back of the bottom surface unit. It is possible to determine the distance with a resolution of 1 nm in the working range of 5 μm. This apparatus was successfully applied to measure the forces between mica surfaces in pure water and aqueous KBr solutions. © 2008 American Institute of Physics.

DOI： 10.1063/1.2903404

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

We report herein the invention of and proof of function for a porous membrane-based electroporation device that can deliver molecules into spatially restricted and predefined areas of a cell monolayer. The device's cell culture substrate is a microporous alumina membrane (pore size 0.02 mu m), with an underlying thin poly-(dimethylsiloxane) (PDMS) film that has one or more holes with diameters in the one-tenth millimeter range. When a transient electric field is generated between the device's two planar electrodes - one of which is placed above the cells and the other below the PDMS layer - the filed condenses only in the volume defined by hole in the PDMS film and therefore localized electroporation can occur. We demonstrate that Lucifer Yellow (LY) and plasmid DNA are selectively introduced into only those HeLa cells located above the holes. Using the device containing a PDMS film with multiple holes, a patterned array of LY-stained cells was resulted. Compared with the operation of and the results obtained from a conventional cuvette electroporation device, our device greatly decreases the necessary operating voltage, can be used with cells attached to a substrate, and increases the number of conditions that can be screened in a single experiment. Finally, since a PDMS film with different sized holes, produces different localized electric field strengths, it is possible to determine the optimum electroporetic conditions in a single experiment. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2007.05.027

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

In this paper, a new type of quartz crystal resonator in which the electrodes are located on (me side has been developed for chemical sensing. The resonator has two electrodes for exciting thickness shear mode (TSM) vibrations on one side of the crystal and a conductive layer on the other side. These electrodes are capacitively coupled with the electric fields in opposite directions, forming an antiparallel coupled resonator (ACR). The resonant characteristics of the ACR were evaluated as a function of gap width between the two electrodes used to excite the TSM. The conductance value was observed to increase with decreasing gap width. We also discovered that the gap should be parallel with the crystallographic x-axis to obtain the highest sensitivity. The frequency response to a viscous loading was almost same as that of a standard quartz crystal microbalance (QCM). The ACR sensor is an attractive alternative to a QCM chemical sensor because it can be easily integrated into packaging and film coatings.

DOI： 10.1021/ac0709910

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

In situ measurements of interfacial phenomena with subatomic resolution under environmental disturbances have been a major goal of engineers and scientists engaged in the development of a microbalance sensor. Here, we demonstrate in situ measurements of the photooxidization process of alkanethiol self-assembled monolayers using dual-channel quartz-crystal microbalance (D-QCM) sensor that uses spherically contoured resonators to acoustically separate sensing channels for simultaneous compensation of environmental disturbances. Using a photolithographic method to make the D-QCM, the reference channel used in parallel with the sensing channel has almost the same resonant frequency and temperature coefficient of frequency. As a result, mass changes of 10-pg order accuracy were observed under ultraviolet radiation over four days.

DOI： 10.1109/JSEN.2006.890165

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

The electrically conducting polymer polypyrrole (PPy) was electrochemically deposited onto Pt microelectrodes on a polyimide (PI) substrate. Pre-modification of the PI surface with a self-assembled monolayer of octadecyltrichlorosilane-induced anisotropic lateral growth of PPy along the P1 surface and enhanced adhesive strength of the PPy film. The lateral growth of PPy film around the electrode anchored the whole film to the substrate. External stimulation of cultured cardiac myocytes was carried out using the PPy-coated microelectrode. The myocytes on the microelectrode substrate were electrically conjugated to form a sheet, and showed synchronized beating upon stimulation. The threshold charge for effective stimulation of a 0.8cm(2) sheet of myocytes was around 0.2 mu C, roughly corresponding to a membrane depolarization of 250 mV. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.biomaterials.2006.11.034

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

Wettability control and bonding of fluoropolymers are important in the microfabrication of microfluidic devices. Here, we demonstrate a process that combines a unique plasma surface modification with surfactant. We employed a tetrafluoro-ethylene-hexafluoropropylene copolymer (PFA) plate dipped into a surfactant solution and briefly exposed to oxygen plasma. We discovered that the contact angle of water on a PFA plate depends on volatility of the surfactant. With this treatment, direct bonding between the PFA plates occurred under low temperature conditions. Finally, we demonstrated the micropatterning of the plate with a shadow mask.

DOI： 10.1143/JJAP.46.367

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We report a method for producing patterned cell co-cultures inside silicone tubing. A platinum needle microelectrode was inserted through the wall of the tubing and an oxidizing agent electrochemically generated at the inserted electrode. This agent caused local detachment of the anti-biofouling heparin layer from the inner surface of the tubing. The cell-adhesive protein fibronectin selectively adsorbed onto the newly exposed surface, making it possible to initiate a localized cell culture. The electrode could be readily set in place without breaking the tubular structure and, importantly, almost no culture solution leaked from the electrode insertion site after the electrode was removed. Ionic adsorption of poly-L-lysine at the tubular region retaining a heparin coating was used to switch the heparin surface from cell-repellent to cell-adhesive, thereby facilitating the adhesion of a second cell type. The combination of the electrode-based technique with electrostatic deposition enabled the formation of patterned co-cultures within the semi-closed tubular structure. The controlled co-cultures inside the elastic tubing should be of value for cell-cell interaction studies following application of chemical or mechanical stimuli and for tissue engineering-based bioreactors. ©2007 IEEE.

DOI： 10.1109/MHS.2007.4420850

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

This paper presents the novel method to control polymer surface morphology using Reactive Ion Etching (RIE) technique and its application to microfluidic devices. This method controls surface morphology in wide range between smooth surface and grassy surface by a newly developed Electron Cyclotron Resonance (ECR)-RIE system. The etching characteristics of 75mol%O2-CF 4 gas mixture were systematically investigated as a function of pressure. The smoothest surface with the roughness (Ra) less than 10 nm was achieved at 0.1 Pa. On the other hand, the grassy surface with high aspect ratio of 80 was uniformly formed in the higher-pressure range from 1.0 Pa to 1.5 Pa. Furthermore, the proposed method was applied to microfluidic channels with multiple pillars, and a hybrid structure with smooth and grassy surfaces. ©2007 IEEE.

DOI： 10.1109/SENSOR.2007.4300105

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

In this letter, we present experimental data showing Q change versus thickness for a quartz-crystal resonator fabricated with deep-reactive ion etching. Measurements show that Q increases as etch depth increases, and further that Q can be optimized as a function of etch depth and diameter of the resonator.

DOI： 10.1109/TUFFC.2006.1665070

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

This paper describes resonant characteristics of spherically contoured AT-cut quartz-crystal resonators, and a novel fabrication process. The fabrication process is based on a photolithographic process suitable for the mass production. Further, the time required to finish quartz blanks into the spherically contoured shape is dramatically less than for conventional methods. Our measurements show that Q of the spherically contoured resonators fabricated with our method are an order of magnitude higher than those resonators without the spherical shape.

DOI： 10.1143/JJAP.45.5283

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

The ability to control of the behavior of living cells in vitro is critical in fundamental cell biology as well as applied biotechnology including tissue engineering and cell-based chip devices. Patterning cells on surfaces is one of the most important approaches to modulate cell behaviors and functions in culture. Here, we describe ongoing work on the newly developed surface patterning technique, "electrochemical bio-lithography", with a focus on the following two subjects: 1) patterning cells within preassembled microfluidic devices and 2) dynamic control of cellular motility.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

The ability to control the behavior of living cells in vitro is critical in a wide range of research fields including fundamental cell biology, tissue engineering, and cell-based chip devices. Patterning cells on substrate surfaces is one of the most important approaches to modulate cellular behaviors and functions in culture. Here, we describe a cell patterning technique based on an electrochemical method, "electrochemical biolithography", which enables the localized immobilization of living cells under typical physiological conditions such as those found in culture media. The present technique is applicable even for a previously cell-patterned substrate and for a grooved substrate, opening new possibilities for the cell-based studies. Also, the integration of this electrochemical technique into a microfluidic device will provide a novel type of cell-chip which enables on-demand immobilization of cells just prior to the use of the device.

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

This paper describes the development of the aluminum nitride (AIN) thin film bulk acoustic resonator (FBAR) using noble MEMS techniques for CMOS integration. An air-gap was fabricated under the resonator for acoustic isolation. Germanium (Ge) was used as a sacrificial layer to make the air-gap. This technique gives high CMOS compatibility. The resonator achieved a Q factor of 780 and an effective electro-mechanical coupling constant (k(eff)(2)) of 5.36% at a resonant frequency of 2 GHz. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.sna.2004.06.014

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ROYAL SOC CHEMISTRY  

A microfabricated bi-convex quartz-crystal microbalance (QCM) with large-radius spherical thickness distribution was realised by reactive ion etching (RIE) and photoresist reflow with solvent vapor. Due to the spherical thickness distribution, the spurious mode was suppressed very well and the resonator has high Q-factor (c.a. 80000). The vibration energy was trapped around the electrode within 5 wafer thicknesses. This value is three times shorter than that of planer QCM. Thus high-density integration and higher productivity per a wafer were realised without any unwanted influence on the Q-factor. The fabricated sensor also has superior resonant characteristic under the viscoelastic liquid.

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The use of microfluidic system is a recent trend in diagnostic assays and bioreactors based on the protein and cellular engineering. Most of microfluidic biodevices would require the combination with a technique to pattern proteins and living cells within microchannels just prior to the use of the devices, since these bio-elements are delicate against desiccation, oxidation and heat. Here, we present a simple, electrochemical method to locally immobilize proteins and cells on substrate surface, easily applicable to the microfluidic system. The integration of the technique into a microfluidic device and the on-demand immobilization of proteins and cells were achieved. The sandwich immunoassay within the microchannel was demonstrated, in which a series of protocols from immobilization to measurement can be carried out under physiochemical conditions. © 2005 IEEE.

DOI： 10.1109/SENSOR.2005.1496381

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

A miniaturized spherical bi-convex quartz crystal microbalance (QCM) array was fabricated by reactive ion etching (RIE) and photoresist reflow with solvent vapor technology. The spherical convex shape is necessary to suppress a spurious mode and obtain a high Q factor. Not only can the large-radius spherical convex shape be achieved by this technology, but also miniaturization and batch fabrication. The Q factor of the fabricated QCM (80000) is two times higher than that of the planar QCM, and the spurious mode around the fundamental vibration mode is suppressed very well. It also has superior resonant characteristic under the viscoelastic liquid.

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

In this paper, miniaturized bi-convex quartz crystal microbalance (QCM) has been fabricated using reactive ion etching (RIE) and melting photoresist technology. Due to the convexity of the resonator surface and the small size of the excitation electrode, the energy of the oscillation is trapped at the center so that very little dissipation occurs at the edge. The fabricated bi-convex. QCM has superior resonant characteristics compared. with a QCM without the bi-convex formation. For example, the QCM with a high-quality value (76 000) was realized for a 1 mm-diameter electrode QCM with 1.6 mum-deep and 2 mm-diameter convex formation on both sides. A spurious mode around a fundamental vibration mode became very small or nearly negligible. This technology is useful from the viewpoint of mass production because it does not require polishing. The manufactured bi-convex QCM can be used for sensing liquid properties. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.sna.2003.12.031

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

A miniaturized biconvex quartz-crystal microbalance (QCM) with large-radius spherical thickness distribution was fabricated by reactive ion etching (RIE) and photoresist reflow with solvent vapor technology. A conventional polishing method could not manufacture the miniaturized, spherically convex shape, which is necessary to suppress a spurious mode and obtain a high Q factor. Not only can the large-radius spherical convex shape be achieved by this technology, but also miniaturization and batch fabrication. The Q factor of the fabricated QCM (80 000) is two times higher than that of the planar QCM, and the spurious mode around the fundamental vibration mode is suppressed very well. It also has superior resonant characteristic under the viscoelastic liquid. (C) American Institute of Physics.

DOI： 10.1063/1.1796535

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER-VERLAG  

In this paper low stress silicon oxide was deposited with tetraethylorthosilicate (TEOS, Si(OC2H5)(4))/ozone by plasma enhanced chemical vapor deposition (PECVD) and sub-atmospheric chemical vapor deposition (SACVD) for deep trench filling. Two kinds of PECVD oxide were fabricated: Coil antenna inductively coupled plasma (ICP) oxide and parallel plates capacitive coupled plasma (CCP) oxide. Adding ozone into the deposition process enhances the trench filling capability. Oxide filling in a deep trench (5 mum wide, 52 mum deep) was carried out using the SACVD process, which gave excellent conformal step coverage. However, the coil antenna ICP oxide was suitable as a sealing material. The effects of argon ion sputtering and magnetic field in the PECVD for the trench filling are discussed in this paper. Because the low temperature processes of PECVD and SACVD, the thermal residual stress was reduced and a low stress film of 85 MPa compression is available.

DOI： 10.1007/s00542-003-0313-z

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

In this work, high-frequency one-chip multichannel quartz crystal microbalance (QCM) prepared by deep reactive ion etching (RIE) is presented. The quartz resonators in one-chip with the diameter in the range 0.05-1.0 mm and thickness in the range 18-82 mum were fabricated. The conductance measurements have shown that Q-factor of the resonators increases with decreasing quartz resonator thickness and reaches the value of about 30,000 for the 94 MHz quartz resonator. By decreasing the thickness, very small resonator with 100 mum diameter can be performed with Q-factor of 5700. The separation of spurious modes from fundamental mode is improved by reducing the diameters of the quartz resonators. The influence of the loading glycerol/water mixtures into the electrical properties of the sensor was conducted. (C) 2003 Published by Elsevier B.V.

DOI： 10.1016/S0924-4247(03)00260-7

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

This article reports on a smooth surface glass etching using deep reactive ion etching with a mixture of sulfur hexafluoride (SF6) and xenon (Xe) gases. A surface roughness of 23 Angstrom was achieved with SF6/Xe(= 1/1) and 18 Angstrom with SF6/Ar(= 1/4) tinder a condition of -390 V self-bias voltage and 0.2 Pa pressure. The surface roughness in the order of several. angstroms (5.9 Angstrom) was obtained at a pressure of 0.1 Pa (SF6 /Xe= 1/1). The average surface roughness (R-a) after the etching by SF6/Xe gas was smaller than those after the etching with SF6 only or SF6/Ar at a same mole fraction of the inert gas to SF6+inert gas. Since heavy inert gas increases the physical sputtering effect, the addition of the heavy inert gas helps to remove contaminant residues remaining on the etched surface. The optimum condition of smooth glass etching With high etch selectivity (21) is a pressure of 0.2 Pa and a mole fraction of Xe to SF6 gas is 8 to 7. We also make an analysis of the relationship between the surface average roughness on the bottom and the etched depth. The average roughness of the etched surface was smooth not only for the bottom but also for the sidewalls. The average surface roughness of the sidewalls was about 16 nm for 50-mum-deep etching under the same optimum condition. This technology was applied to a deep etching of quartz crystal used for a mass sensor. (C) 2003 American Vacuum Society.

DOI： 10.1116/1.1624272

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

An endpoint detectable plating process to avoid over-electroplating was proposed and performed in this work. The technology was developed for fabrication of Pyrex glass wafer with electrical feed-throughs. Thin film of gold was deposited on the glass wafer prior to the femtosecond laser drilling. When the growing metal in the through-holes was contacted to the metal, a resistance between the opposite two electrodes decreases suddenly. Thus, the endpoint detection was realized by in situ monitoring of applied voltage at constant current mode. After the endpoint detection, periodic reverse plating was applied to fill the through-holes uniformly. Finally, uniform copper deposition in the through-holes up to 12 aspect ratios was realized by this method. This technology was also applicable to the fabrication of microstructure based on electroforming. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0924-4247(03)00262-0

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dA highly selective dry-etch process for conductive metals (Au, Pt, and Cu) and magnetic metal (20% Fe-Ni) has been developed using a magnetron reactive-ion-etching system employing a CO/NH3/Xe chemistry. Etch selectivities of these metals to titanium are greater than 80: 1 for Au, 40: 1 for Pt, 30: 1 for Cu, and 15: 1 for permalloy (20% Fe-Ni) at the titanium-etch rate of 1.0 nm/min. The etching was conducted at room temperature. It was observed that the small addition of Xe to CO/NH3 etch gases (molar ratio= 1/7) increased the etch rate of these metals while promoting nitridation of the titanium mask and achieving enhanced selectivity. The titanium can be used both as a mask for the sputter etching of noble metals and as a mask for the reactive-ion etching of magnetic metals in the plasma. By about a factor of 3, the inclusion of Xe enhanced the etch selectivities for noble metals, copper, and a magnetic metal over titanium. (C) 2003 American Vacuum Society.

DOI： 10.1116/1.1612516

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DOI： 10.1109/MWSYM.2003.1210489

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DOI： 10.1109/SENSOR.2003.1217131

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

An endpoint detectable plating process to avoid over-electroplating was proposed and performed in this work. The technology was developed for a fabrication of Pyrex glass wafer with electrical feed-throughs. Thin film of gold was deposited on the glass wafer prior to a femto-second laser drilling. When a growing metal in the through-holes was contacted to the gold, a resistance between the opposite two electrodes decreases suddenly. Thus the endpoint detection was realized by in situ monitoring of applied voltage at constant current mode. After the endpoint detection, periodic reverse plating was applied to fill the through-holes uniformly. Finally, uniform copper deposition in the through-holes up to 12 aspect ratios was realized by this method.

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

In this paper the etching of Pyrex glass assisted by femtosecond pulses is reported. The process consists of 2 steps: (1) irradiating the glass by focused pulses from a femtosecond laser, (2) etching the glass in diluted HF (hydrofluoric acid) a solution. The glass can be modified without cracking by applying a femtosecond laser with a very low intensity. The etched depth of Pyrex glass increases from 12 to 131 mum with femtosecond laser irradiation from 0 to 1170 kJ/cm(2), and etching in a 5% HF solution for 230 min. This technique provides an alter-native way of achieving a high etching rate of Pyrex glass for applications to micro-electro-mechanical systems (MEMS), and of forming suspended structures on the surface of a Pyrex glass substrate by using modified glass as a sacrificial layer.

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

In this paper, the energy dissipation in small-diameter Quartz Crystal Microbalance (QCM) was experimentally studied for ultra-high sensitive gravimetric measurements. Newly developed deep reactive ion etching technology for smooth surface glass etching was used for the fabrication of small-diameter QCM. Minimum average surface roughness is 2.3 nm for an etching with SF6/Xe (=1/1) gases and 1.8 nm for SF6/Ar (=1/4) gases at a pressure of 0.2 Pa with a self-bias voltage of -390 V. The diameters of fabricated QCM were 0.2-1.0mm and their thickness was in the range of 6-82mum. The Q-factor of the fabricated QCM increases exponentially from 2000 to 10000 as the thickness decreases due to the decrease of supporting loss. Interestingly, the increases of Q-factor deviate from simple exponential function and show a maximum peak of the Q-factor (30000).

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

In this paper, high sensitive, miniaturized plano-convex quartz crystal microbalance (QCM) has been fabricated by reactive ion etching (RIE) and melting photoresist technology. Due to the convexity of the resonator surface and the small size of the excitation electrode, the energy of the oscillation is trapped at the center so that very little dissipation occurs at the edge. The fabricated plano-convex QCM has superior resonant characteristics compared with a QCM without the plano-convex formation. For example, the QCM with a high,quality value (60000) was realized for a 1-mm-diameter electrode QCM with 1.6-mum-deep and 2-mm-diameter convex formation on both sides. A spurious mode around a fundamental vibration mode was also suppressed less than 20% from that before the etching. This technology is useful from a. viewpoint of mass production because it needs not polishing.

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

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

This paper describes the fabrication technology for high-density electrical feed-throughs in Pyrex glass wafers. Small through holes (40-80 mum in diameter) in Pyrex glass wafers have been fabricated using deep-reactive-ion etching (DRIE) in a sulfur hexafluoride (SF6) plasma. The maximum aspect ratios obtained were between 5 and 7 for a hole pattern and 10 for a trench pattern. Through the wafer etching of a hole pattern of 50 pm diameter was carried out using 150-mum-thick Pyrex glass wafers. The electrical feed-throughs in the wafers were fabricated by filling the through-holes with electroplated nickel. We were able to successfully bond the glass wafer to silicon by anodic bonding after removing the electroplated nickel on the surface of the wafer by chemical-mechanical polishing (CMP). The electric resistance of the feed-through was estimated by a 4 point wire sensing method to be about 40 mOmega per hole. The heat cycles test shows that the resistance changes were within 3% after 100 cycles. The fabrication of high density electrical feed-throughs is one of the key processes in the field of MEMS. Probable applications of this technology are in electrical feed-throughs between logic elements and microprobe arrays for high-density data storage and for packaged devices.

DOI： 10.1109/JMENS.2002.805211

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

A miniaturized highly sensitive single-chip multichannel quartz-crystal microbalance prepared by deep reactive ion etching is presented. In the present work., quartz resonators in a single-chip with the diameters in the range 0.05-1.0 mm and thicknesses in the range 18-82 mum were fabricated. The conductance measurements carried out on the resonators showed that the Q factor is inversely proportional to resonator thickness. The Q-factor value. as high as similar to30000 has been observed in case of a 94 MHz resonator whose diameter is 1 mm and the thickness 17.8 mum. The Q factor of a resonator of very small diameter (0.1 mm) reached the value 5700. (C) 2002 American Institute of Physics.

DOI： 10.1063/1.1532750

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In this work, new novel methods for fabricating a thermal probe array with 32 × 32 probes on one chip are proposed. It consists of silicon micromachined probe, AIN actuator, pyramidal SiO2 tip on which the nano-scale metal-metal junction is formed using a self-alignment technique. The nano-junction can be used as a thermocouple to measure a local temperature on a sample surface or as a nano-heater to make a local deformation on a media. In self-alignment process, a metal layer (Pt/Ni) is deposited on the inside of SiO2 hollow tip fabricated by low temperature (950 °C) oxidation of silicon etch pit. This low temperature oxidation results in a smaller oxide thickness at the tip apex than other flat area. Therefore, after selective etching the SiO2 in buffered HF, a small hole surrounding the Pt/Ti tip apex can be created. Another metal (Ni) is deposited outside the Pt/Ti tip to make the nano-junction. For electrical interconnection between the thermal probe and an IC chip, a hole array with 30 μm of a hole diameter is made by dry etching through the 150-μm-thick Pyrex glass, and then Ni is electroplated into the through etched-hole. Finally the Pyrex glass plate was anodically bonded to the probe array. Using the fabricated thermal probe, temperature distribution is measured on a prepared sample surface and the local heating capability of the thermal probe is confirmed. Preliminary experiments for data writing and reading are performed on a phase change medium.

DOI： 10.1109/JMEMS.2002.1007400

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Interactions between opposed brush layers of polyelectrolytes ionized poly(L-glutamic acid) (PLGA) or poly(L-tysine) (PLL) in water were directly investigated using surface forces measurement. The brush layers were prepared by the Langmuir-Blodgett deposition of amphiphiles bearing PLGA (degree of polymerization n = 21,44, and 48) or PLL (n = 41 and 52) as hydrophilic groups. The density of polyelectrolyte chains was around 0.4 chain/nm(2). Surface force profiles, consisting of a long-range electrical double layer repulsion and a short-range steric repulsion, were measured and analyzed with varying pH, salt concentration, and polyelectrolyte chain length. The surface potential obtained from the double layer repulsion indicated that nearly all of the ionized groups in the brush layers were neutralized by counterions. In the case of PLGA, the steric repulsion of the brush layer increased with increasing pH from 9 to 10, reflecting the increase in the ionization degree of the carboxylic groups, and then decreased above pH 10 due to salt effect. Similar behavior was also observed for PLL: the steric repulsion increased when the pH was changed from 4 to 3 and decreased at pH 2. In the cases of both PLGA and PLL, the steric repulsion decreased with increasing salt concentration (0.43-10 mM) at a fixed pH, which was likely due to a decrease in the osmotic pressure of the counterions. The distance at which the steric repulsion appeared (Do) corresponded to twice the length of an extended polyelectrolyte molecule. This distance Do remained practically the same under the pH and salt conditions studied for the brush of an identical polymerization degree. Twice the length of polyelectrolyte chains L-0 was defined as Do - 6 (nm), where 6 nm was twice the length of the long alkyl chains in polyelectrolyte amphiphiles, and was found to be proportional to the polymerization degree of polyelectrolyte n. The stress profiles, obtained by differentiating the force profiles, were scaled according to the distance to provide identical profiles for different polymer chain lengths. An equation describing the stress profiles was derived based on a model that attributed the steric force to the osmotic pressure of the counterions. The equation reproduced well the stress profiles of PLGA and PLL brushes, where the osmotic coefficient was a variable parameter. The osmotic coefficient was estimated to be 0.004 for both PLGA and PLL and much less than the value determined in solution (similar to0.2), indicating that the counterions bound more strongly to the polyelectrolytes in the brush layer than to isolated polyelectrolytes in solution. The advantage of characterizing polyelectrolytes by surface forces measurement was discussed.

DOI： 10.1021/la0114979

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

In this article, we describe more than 100-mum-deep reactive ion etching (RIE) of silicon carbide (SiC) in oxygen-added sulfur hexafluoride (SF6) plasma. We used a homemade magnetically enhanced, inductively coupled plasma reactive ion etcher (ME-ICP-RIE) and electroplated nickel masks. First, 5 h etching experiments using etching gases with 0%, 5%, 100% and 20% oxygen were performed by supplying rf power of 150 and 130W to an ICP antenna and a sample stage, respectively. They demonstrated a maximum etch rate of 0.45 mum/min and residue-free etching in the case of 5% oxygen addition. Observation of the cross sections of etched samples using a scanning electron microscope confirmed a microloading effect, which is reduction of the etched depth with a decrease in the mask opening width. Next, a 7 h etching experiment using an etching gas with 5% oxygen was performed by increasing the rf power to the sample stage to 150 W. This yielded an etched depth of 216 mum. (C) 2001 American Vacuum Society.

DOI： 10.1116/1.1418401

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

Deep reactive ion etching of Pyrex glass has been characterized in sulfur hexafluoride plasma (SF6). High etch rate (similar to0.6 mum/min) was demonstrated under a condition of low pressure (0.2 Pa) and high self-bias (-390 V) by using a magnetically enhanced inductively coupled plasma reactive ion etching. Vertical etch profile (taper angle similar to 88 degrees), high aspect ratio (&gt;10) and through-wafer etching of Pyrex glass (200 mum in thickness) were achieved under the condition by using thick (20 mum) and vertical electroplated nickel film as mask. The vertical etch profile was achieved when the mask opening is narrower than 20 mum because the deposition of nonvolatile product on the sidewall is reduced. A novel etching technique "scoop-out etching" was demonstrated by using the present etching characteristics. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0924-4247(00)00482-9

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER-VERLAG BERLIN  

Micro-pattern formation of PTFE nanoporous film was realized by using pulsed electrodeposition from aqueous disperision of PTFE particles. The volume fraction of PTFE in a nickel matrix was more than 50 vol.% when the pulse-on and the pulse-off time were controlled to be 10 msec and 2 msec, respectively. In this condition, the PTFE particles embedded in the matrix fused each other by annealing the film under the temperature of 300 degreesC. After removing the nickel by acid, the obtaiend PTFE film had nanopore and it brought ultrahydrophobic effect.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Brush layers of polyelectrolytes, ionized poly(L-lysine) (PLL) or poly(L-glutamic acid) (PLGA), at desired densities were prepared by the Langmuir-Blodgett (LB) deposition of amphiphiles bearing PLL or PLGA segments as hydrophilic groups, and subjected to the surface force measurements. Abrupt changes in the surface force, the surface potential, and the transfer ratio of the brush layers were observed at a critical density. The present data is in good agreement with our previous report on the jump in the compressibility of the brushes, and supports the existence of the density dependent transition of polyelectrolytes in solutions.

DOI： 10.1080/10587250108024758

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

This paper reports a new fabrication technology of Pyrex glass with a fine pitch electrical feedthrough. Small through holes (40-60 mum in diameter) in Pyrex glass plate have been fabricated using deep reactive ion etching in sulfer hexafluoride (SF6) plasma. By filling the through holes with electroplated metal, the fine pitch electrical feedthrough in Pyrex glass plate becomes enable technology. Pyrex glass can be anodically bonded with silicon. Thus, our technology will be widely used for high density electrical feedthrough to the backside of a plate. The applications of the technology to micro probe array used for high density data storage and packaged devices are expected.

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

Brush layers of a polyelectrolyte, ionized poly(glutamic acid) (polymerization degree n = 48), were studied using FTIR spectroscopy as a function of the polyelectrolyte chain density. The Langmuir-Blodgett (LB) deposition of the mixed monolayers of a poly (glutamic acid) functionalized amphiphile and dioctadecylphospholic acid afforded the preparation of polyelectrolyte brushes at the desired density on various substrates. FTIR spectroscopy on the LB films demonstrated that the ionization degree of the carboxylic acid groups decreased with increasing polyelectrolyte density in order to maintain the charge density below the critical value of 0.8 similar to 1 charge nm(-3). The average distance between the charges at the maximum density was ca. 1.1 +/- 0.1 nm which is close to twice the Bjerrum length, the distance at which the Coulomb interaction between elementary charges is equal to the thermal energy. (C) 2000 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0927-7757(00)00470-2

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

In this paper, we present a one-chip multichannel quartz crystal microbalance (QCM) sensor fabricated by deep reactive ion etching (Deep RIE). An inductively coupled plasma reactive ion etching (ICP RIE) using SF, gas has been applied to the Deep RTE of quartz. High etch rate (similar to 0.5 mu m/min) and mirror surface (roughness, similar to 2 nm) were achieved at the conditions of low process pressure (2 mTorr) and high self-bias voltage (- 340 V). The multichannel QCM sensor, which has different resonance frequencies, was formed by fabricating diaphragms of different thicknesses on a single crystal of quartz plate. The resonance frequencies ranged from 21.7 to 20.75 MHz. The Q factors of each peak were approximately 2000 in air and the resolution for mass change was +/-1 ng on 2-mm-diameter electrode. We have successfully shown that the sensor with different coating films can be applied to chemometric odor sensor. (C) 2000 Elsevier Science S.A. All rights reserved.

DOI： 10.1016/S0924-4247(99)00330-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Interactions between apposed brush layers of polyelectrolytes ionized poly(L-glutamic acid) (polymerization degree n = 21, 44, 48) were investigated in water at pH 10 by the direct surface forces measurement. Brush layers were prepared by the Langmuir-Blodgett (LB) deposition of amphiphiles bearing a poly(L-glutamic acid) chain and two octadecyl groups. The obtained surface force and stress profiles consisted of a long-range electrostatic repulsion and a short-range steric repulsion. The distance where the steric repulsion appeared was in good agreement with twice the length of the polyelectrolyte chains in the extended form. The stress profiles of the polyelectrolyte brushes at n = 21, 44, and 48 produced the identical curve when the distance was scaled by the length corresponding to twice the thickness of an undeformed polyelectrolyte layer. Interactions between the layers of a poly(L-glutamic acid) (n = 48) were also studied as a function of the polyelectrolyte chain density in the brush layers. The density was varied by mixing the poly(L-glutamic acid) amphiphile with dioctadecylphosphoric acid. The sudden increase in the short-range repulsion attributed to the steric component was found at the critical density of 0.20 +/- 0.07 chain/nm(2) with decreasing chain density in the brush layers, indicating the existence of the transition in the interaction mode of polyelectrolytes. The steric repulsion was quantitatively analyzed to provide the elastic compressibility modulus of the polyelectrolyte brushes. The obtained modulus of 0.6 +/- 0.1 pN/chain was in the high-density region, and 4.4 +/- 0.7 pN/chain was in the low-density region. The transition in the counterion binding to polyelectrolytes may account for the density-dependent change in the interactions of the polyelectrolyte chains.

DOI： 10.1021/la990240w

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Direct measurement of surface forces has been employed for the systematic determination of interaction forces between nucleic acid base monolayers at various pH values from 5.6 to 9.3. Measured forces have been classified as (1) forces at a distance D &gt; 20 nm, which are attractive or repulsive depending on the hydrophobicity and the charge of the surfaces and which can be accounted for in terms of the sum of &apos;&apos;double-layer forces&apos;&apos; and so-called &apos;&apos;very long ranged hydrophobic attraction&apos;&apos;; which are always attractive; and (3) pull-off (adhesive) forces from contact, which reflect characteristics of molecular contact between monolayers of nucleic acid bases. The forces between complementary pairs (adenine-thymine) are found, for the first time, to be always attractive and stable independently of separation distances as well as pH&apos;s studied. On the other hand, interactions between noncomplementary pairs (thymine-thymine, adenine-adenine) are found to be regulated by the surface charge; thus, notably the long-ranged forces change from attractive to repulsive at pH&apos;s where the nucleobases start to dissociate.

DOI： 10.1021/la950867o

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

Interactions between apposed poly(L-glutamic acid) monolayers in water were investigated by direct surface forces measurement. The average degree of polymerization was 21. The monolayers of anchored poly(L-glutamic acid) were prepared on mica surfaces by the Langmuir-Blodgett deposition of monolayers of an amphiphile containing the polypeptide as the hydrophilic head group. Various secondary structures of poly(L-glutamic acid) were formed in this monolayer at the air-water interface, through intra- and intermolecular hydrogen bonding, depending on the surface pressure and the pH value of the aqueous subphase, and transferred onto mica surfaces. Formation of the secondary structures was characterized by Fourier transform-infrared (FT-IR) spectroscopy prior to the forces measurement. Surface force profiles consisted of a long-range electrostatic and a short-range steric repulsion. Secondary structures of poly(L-glutamic acid), identified by FT-IR with respect to their composition and orientation, were found to determine the short-range steric repulsion. The obtained elastic compressibility moduli of the polypeptide monolayers were 5.6 +/- 2.2 MPa for the beta(2)-structure rich layer, and 0.2 +/- 0.1 MPa for the layer of ionized extended chains.

DOI： 10.1016/0927-7757(95)03295-O

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Interactions between apposed poly(L-glutamic acid) monolayers in water were investigated by direct surface force measurements. The average degree of polymerization was 21. Surface force profiles consisted of a long-range electrostatic repulsion and a short-range steric repulsion. Secondary structures of the polypeptide were found to determine the short-range steric repulsion. The elastic compressibility moduli of the polypeptide monolayers were obtained to be 5.6 +/- 2.2 MPa for the beta(2)-structure-rich layer and 0.2 +/- 0.1 MPa for the layer of ionized extended chains.

DOI： 10.1021/j100007a003

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER SCIENCE PUBL B V  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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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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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

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   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

In this paper, we report the development of non-contact type alcohol concentration detection method using a quartz crystal resonator. This detection method was realized by using an interdigital capacitor (IDC) located at a backside of glass substrate for sensing the liquid on the substrate. Multi-point measurement can be done by fabricating multichannel IDC. Frequency changes by a change in the relative permittivity caused by dropping the liquid on the substrate. Since the relative permittivity is dependent on the concentration of the liquid, it is possible to measure the concentration of alcohol. The proposed method is expected to use for non-contact measurements of liquids.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

We developed a single microheater combined quartz crystal microbalance array for thermal desorption spectroscopy. In this study, new designs of the microheater were fabricated and frequency stability of fabricated sensor was compared between the new designs of the microheater. In a design of the microheater, the frequency stability (3 σ) calculated from the frequency change for 60 sec was 1.4 Hz when the sensor was heated to a temperature of 140 degrees Celsius. The design was effective to improve the frequency stability under heating. In addition, identification between methanol and ethanol was carried out by using the sensor.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

QCM (Quartz crystal microbalance) is used as viscoelastic sensor not only as mass sensor. If it can measure the electric properties, it is expected to use for various applications. In this paper, a dual quartz sensor using a leakage electric field has been developed for analyzing the physicochemical properties of liquids. This sensor can measure the mechanical properties and the electrical properties simultaneously by integrating two types of ACR (Antiparallel coupled resonator) sensors on a same substrate. One is the sensor for measuring the viscoelasticity, another is the sensor for measuring the conductivity and dielectric constant. By changing the electrode portion on the sensing surface of ACR, ACR can evaluate the electrical properties of liquid using a leakage electric field. And this sensor can improve its stability in the air by adjusting the electrode area on the sensing surface.

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Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.  

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Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)  

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Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)  

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Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.  

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Language：Japanese   Publisher：東北大学グローバルCOEプログラム「新世紀世界の成長焦点に築くナノ医工学拠点」  

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Language：Japanese   Publisher：電気化学会化学センサ研究会  

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

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Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)  

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DOI： 10.1088/0957-4484/14/9/321

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：The Society of Instrument and Control Engineers  

DOI： 10.11499/sicejl1962.42.5

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Other Link： https://jlc.jst.go.jp/DN/JALC/00163639185?from=CiNii

A novel fabrication method of a micro-thermal probe and its array for nanometric thermal imaging and a technological approach for probe-based data storage are presented. A small metal wire for a nano-heater is fabricated at the apex of a pyramidal SiO2 tip, which is formed by low temperature oxidation of a silicon etch-pit at 950°C, consecutive metal deposition (Pt/Cr or Au/Cr) to fill the metal into the etch-pit, and etching of the SiO2 in buffered HF solution. Another metal (Ni) is deposited on the small wire to form a metal-to-metal junction that enables to measure the temperature at the tip end. Metal feed-through are formed on a glass substrate that is bonded with the probe array, which enables to transmit a high-speed signal to a processing-circuit and increase the probe array density. Using the thermal probe, temperature distribution on a sample surface is measured. The heating capability of nano-heater is confirmed by the resistivity change and thermophoton emission from the nano-heater when flowing a small current into the nano-heater. By using a micro-probe, preliminary experiment for data writing and erasing is performed on phase change medium.

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Language：English   Publisher：IEEE  

A micromachined thermomechanical relay with Au microspring contact array is presented. Thermally excited Al-SiO2 bimorph cantilevers have been fabricated with micromachining technology Sputtered Au/Pt/Ti contacts are formed on the tip of the cantilevers and microheaters are built in the cantilevers. In order to reduce the ON-resistance and to avoid the metallic binding between Au contacts, Au microspring contact array is fabricated on Pyrex glass. The fabricated thermomechanical microrelay is operated with input power levels ranging from 20-80 mW at frequencies up to 3 KHz. The ON resistance R-ON, that includes contact resistance and signal line resistance is in the range of 200-500 m Omega and switching time is about 300 mu sec. 10(7) cycles operation has been performed keeping the R-ON around 300 m Omega.

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