This paper describes a novel design of MEMS variable capacitor with high quality factor and wide tuning range. The proposed MEMS variable capacitor is composed of two cross movable electrodes and one dielectric layer between them. The fabrication process does not require any complex processes, such as wafer transfer, wafer backside etching, special planarization or supercritical point drying. The capacitor has tuning range of 330% at 5 V bias voltage, and an overall quality factor of 52 at 2 pF and 2.4 GHz.

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This paper is concerned with a new approach for sensor data processing for sensor networks in which multiple sensors are supposed to monitor overlapping part of the environment. The proposed method is based on collective synchronization of nonlinear coupled virtual oscillators whose natural frequencies are set to sensor data. Under appropriate conditions, the oscillators are locked to a common frequency. This convergent behavior is interpreted as data processing for bleaching and classification of noisy sensor data.

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This paper presents the development of a dual axis convective microaccelerometer, whose working principle is based on the convective heat transfer and thermo-resistive effect of lightly-doped silicon. Different with developed convective accelerometer, the sensor utilizes a novel structure of the sensing element which can reduce 93% of thermal-induced stress. Moreover, the thermistors are made from low-doped p-type silicon, which has the TCR higher than that of metals and poly-silicon convective accelerometer. By using numerical method, the chip dimensions and the package size are optimized. The sensitivity of the sensor was simulated; other characteristics such as frequency response, shock resistance, noise problem are also deeply investigated. The sensor has been fabricated by MEMS process and characterized by experiments.

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3-dimentional Ni microprobe has been developed using an X-ray lithography and electroplating method for IC microchip. A probe for the actual probe card must be durable enough to repeat touch 10,000 times or more at an ambient temperature of approximately 358K. In order to evaluate the durability of Ni-plated material that forms the microprobe, a simplified test piece was used. As a result, it was found that despite the deformation being within the limit of elasticity, a phenomenon similar to creep caused the deformation to persist even after the stress had been removed. Although such a phenomenon has already been verified in ordinary materials at high temperature, it has now also been verified in Ni-plated materials at low temperature. This seems to be attributed to the fact that Ni-plated materials have a minute grain size of several tens of nanometers, and because the Ni coating absorbed hydrogen and impurities from aqueous solution during plating. After heating the Ni-plated material to 373 to 573K, the deformation was dwindling noticeably. It has been established, therefore, that heat treatment is effective in improving the durability of Ni-plated structures manufactured by an X-ray lithography and electroplating method.

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A microfluidic system to transport and mix solutions was fabricated and used for the detection of amino acids. A solution filled in the injection port was transported through a space between an elongated gold working electrode and a protruding structure of polydimethylsiloxane (PDMS). The transport was possible because the electrode surface was made hydrophilic by changing the potential of the gold working electrode. The same principle was used to mix two solutions. To demonstrate the system's applicability, optical biosensing based on electrochemiluminescence (ECL) was conducted on the chip. A necessary reagent solution (Ru(bpy)₃²⁺) and a sample solution (amino acid) were transported and mixed. ECL was observed on a platinum working electrode by applying a positive potential. Linear relationships were observed between the ECL intensity and the amino acid concentration.

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A microfluidic system with injecting and flushing functions was developed. In the system, hydrophilic flow channels have a dry-film photoresist layer which facilitates the introduction of solutions from four injection ports. The injection and flushing of solutions are controlled by valves operated by electrowetting. The valves consist of gold working electrodes in the flow channels or a through-hole in the glass substrate. Solutions can be sequentially introduced through the injection ports into a reaction chamber and flushed through a valve in the through-hole. Necessary immunoassay steps can be conducted on the chip, and a target antibody can be detected electrochemically.

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Wrong:Ysunaga Mitsuya
Right:Yasunaga Mitsuya

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