This paper describes three-dimensional (3D) micro structures fabricated using a simple self-assembly process involving the thermal shrinkage of polyimide. The proposed method enables hinged structures automatically to be rotated out of the wafer plane and to remain bent without the need to use any interlocking mechanisms. The hinged structures were fabricated using surface micromachining techniques involving heating in a furnace. An increase in the bending angle due to the shrinkage of polyimide was observed with increasing heating time, heating temperature, and length of the polyimide hinge. Of these three parameters, the heating time was found to be the most suitable for control of the bending angle. Microcubes were fabricated by this method and the self-assembly process was successfully visualized using a CCD camera. Furthermore, the hinged structures were actuated in external magnetic field after the self-assembly.

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In this paper, a new sequential stacking self-assembly using interfacial tension of two different droplets of TEGDMA (Triethyleneglycol Dimethacrylate) and 42Sn-58Bi solder was proposed. TEGDMA with an additional thermal initiator is liquid at room temperature and hardens by heat. 42Sn-58Bi solder is solid at room temperature and melts at 138 °C. Since interfacial tension of TEGDMA and 42Sn-58Bi solder are selectively utilized by setting the process temperature at room temperature for TEGDMA and 150 °C for 42Sn-58Bi solder, the sequential self-assembly of different components can be realized. The feasibility of the proposed process and alignment accuracy were experimentally examined using 1 mm square silicon chips as test components. The first component assembly on a substrate was carried out at room temperature using TEGDMA as an adhesive agent, and the second component assembly on the assembled component was carried out at 150 °C using 42Sn-58Bi solder as an adhesive agent. Both self-assembly processes were carried out in EG (Ethylene Glycol) solvent with an additional sulfuric acid. It was confirmed that the first and second self-assembly was successfully done at room temperature and at 150 °C, and alignment accuracy of first and second self-assembly were 33 μm and a few μm, respectively.

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We propose a surface treatment technique to effectively avoid both process stiction and in-use stiction of silicon MEMS (microelectromechanical system) devices by using all-vapor processes: vapor HF (hydrofluoric) acid for sacrificial release, UV ozone for oxidation, and vapor HMDS (hexamethyldisilazane) for SAM (self-assembled monolayer) coating of small surface free energy. Adhesion force at every stage of the surface treatment was studied by using the force-curve of the AFM (atomic force microscope) measurement. HMDS-SAM coated silicon surfaces were found to have small adhesive strength of one fifth of that between the oxidized silicon surfaces. The effectiveness of the surface treatment was also experimentally validated by applying to an electrostatic optical MEMS scanner, which was practically used as a fiber-optic component.

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This paper deals with a pyrolyzed polymer as a kind of carbon materials obtained by pyrolysis of polymers. Through a combination of micromachining of polymers and following pyrolysis process, we can obtain pyrolyzed polymer MEMS structures for various applications. This work focuses on the effect of NO₂ gas adsorption on electrical properties of pyrolyzed polymers. The resistance of the sensor is dramatically decreased when the sensor is exposed to the NO₂ gas. It is found that low pyrolysis temperature and high operating temperature contribute to higher sensitivity against gas mixture of NO₂.

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In this report, ITO(Indium Tin Oxide) was used on the glass substrates as the transparent electrode, and ZnSe layer was prepared by the vacuum deposition on this ITO. Then, the electrical characteristics of this sample were investigated by mans of the electric current transport analysis. The sample that ZnSe was prepared as 3.4 μm in case of ITO-ZnSe sample, has high density level at the junction surface. The ITO-ZnSe junction has two type of diffusion current. However, the ITO-ZnSe sample that ZnSe layer was prepared as 0.1 μm can be assumed as the ohmic contact, and ITO-ZnSe(0.1μm) -CdTe sample shows the avalanche breakdown, and it is considered that the avalanche breakdown occurs in CdTe layer. It is difficult to occur the avalanche breakdown, if ZnSe-CdTe junction has high-density level and CdTe layer has high-density defect. Hence, the ZnSe-CdTe sample that CdTe layer was prepared on ITO-ZnSe(0.1μm) substrate has not high-density level at the junction surface, and the CdTe layer with little lattice imperfection can be prepared. It found that ITO-ZnSe(0.1μm) substrate is available for the II-VI compounds semiconductor device through above analysis result.

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We developed a thermal anemometer using a novel sensor chip fabricated by the silicon micromachining technique. A chip scale wind tunnel on the sensor chip allowed the fluid to flow from the front to back side. Since conventional sensors using a micro-air-bridge heater were placed parallel to air flow, the heat transfer from the heater was influenced by turbulence generated from a chip edge or other micro structures. We expected that the chip scale wind tunnel bound air flow to keep regularity of heat transfer. By using the sensor chip, we produced a prototype thermal anemometer, and measured characteristics. The anemometer could measure wind velocity in the range of 0∼35m/sec. The directivity to wind direction was very symmetric at 5, 10, 15 and 20m/sec.

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In this paper, it is described to obtain information on a temperature and wind velocity as physical quantities by multi-functional measurement using a thermistor. The temperature in the ranges from 25 °C to 35 °C and wind velocity in the ranges from 1 m/s to 4 m/s based on multi-functional measurement using the thermistor with supplied currents of 2.5 mA and 5 mA are measured as a database. From the measurement results, the possibility of realization of this multi-functional measurement of the temperature (The resolution is about 0.2 °C.) and wind velocity (The resolution is about 0.4 m/s.) by the thermistor was shown.

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This paper describes a technology to prevent sticking between actuator and control electrode during microelectromechanical system device operation. The technology involves the electrodeposition of organic dielectric film on the gold electrode. The focus is on solving the problems found on gold surfaces that have passed through many fabrication-process steps, which are an incubation period and two types of anomalous growth (selectivity loss and skirt growth). Two pre-treatments and one post-treatment solve each problems, respectively. The incubation period is eliminated by dipping in hydrochloric acid as a pre-treatment, which dissolves gold oxides formed during the oxygen plasma exposure used for surface cleaning or sacrificial layer ashing. The anomalous growth is suppressed by adding a hydrofluoric acid dip as a pre-treatment to improve the selectivity and by annealing the films below the glass-transition temperature as a post-treatment to suppress large film reflow. The fabricated cantilever structure with the electrode coated using this technology exhibits a conformal coating with excellent isolation between the cantilever and the electrode.

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In this paper, we monitored the electromagnetic waves generated by human activity. We investigated a monitoring system that used the bioelectric potential of a plant. Four subjects walked on the spot at a distance of 60 cm from a rubber tree and we measured the variation in the bioelectric potential of the tree produced by the stepping motion. The results confirmed that the electromagnetic waves generated by a person walking on the spot produced a measurable response in the bioelectric potential of a plant. It was also found that this variation in the bioelectric potential varied in synchrony with the subject's walking pace.

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