Availability of a novel micro-valve made of paraffin wax which is used in a “swallowable biosensor” is studied. The valve was composed of a plug made of paraffin wax which sealed a micro fluid channel and micro heater to melt the paraffin plug. Additionally, a collecting area of paraffin after melting was formed downstream of the paraffin valve to prevents the melted paraffin from influencing on another devices in the swallowable biosensor. Shape of the collecting area for the melted paraffin was optimized by simulation using finite element method (FEM). As the result of simulation, it is found that two sloped weir, which is staggered each other, collected the most melted paraffin. Fabrication of the paraffin valve and the weirs collecting for the melted was also carried out. As a result of collecting test of melted paraffin, it was observed that two sloped weir collected most melted paraffin, which is the same result as the simulation.

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The purpose of this work is in-plain manipulation of dispersed magnetic beads on a chip. This makes an immunoassay chip completes all its procedures on itself and eliminates any off chip components. A test chip was drawn in 180nm standard Complementary Metal Oxide Semiconductor (CMOS) process and tested. Beads those have a diameter of 2.8µm were diluted and applied onto the chip. The chip successfully manipulated them with an affordable current down to 5mA.

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The positive list system for pesticide residues in food was introduced in Japan in 2003. Under this system, the number of regulated pesticides has increased, and a long-time analysis of pesticide residues is required. A new assay method for detecting pesticide residues more efficiently is also required. In this study, we developed a screening method for the detection of pesticide residues using a surface plasmon resonance (SPR) sensor. Self-assembled monolayers (SAMs) were formed on the sensor surface using alkanethiols. Surfactants were used as auxiliary agents in pesticides. The adsorption characteristics of the surfactants were investigated using the SPR sensor with a SAM-modified surface. We used an eicosane thiol SAM for a nonionic surfactant and an N,N,N-trimethyl(16-mercaptohexadecyl)ammonium (C16-TMA) SAM for an anionic surfactant. As a result, a detection limit of 30ppb was achieved for imazalil and glyphosate with the anionic surfactant and a detection limit of 80ppb was achieved with the nonionic surfactant using the SPR sensor.

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We tried to make a CO₂ sensor using a quartz crystal microbalance (QCM) coated with acrylonitrile-styrene copolymer (AS). Concentration of CO₂ gas diluted with dry N₂ gas was measured using the QCM whose output is frequency shift. Sensitivity of the QCM to Ar, O₂ and humidity was also examined because atmosphere is composed of N₂, O₂, CO₂, Ar and water vapor. Consequently it was revealed that the QCM coated with AS is sensitive to not only CO₂ but humidity and insensitive to O₂ and Ar. Next relationships between concentration of CO₂ gas diluted with damp N₂ gas and frequency shift of the QCM were examined. Consequently it was clarified that the frequency shift compensated for influence of humidity is nearly equal to the frequency shift caused by CO₂ gas diluted with dry N₂ gas. Accordingly it was shown that concentration of CO₂ gas in atmosphere can be measured using the QCM. Furthermore it was found that sensitivity to concentration of CO₂ and humidity grows higher with increasing thickness of AS membrane.

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Previously, we have reported electromagnetically driven 2-axis tilting MEMS mirror, 2-axis tilting grating and 3-axis movable MEMS mirror (2-axis tilting and 1-axis vibration). These devices can be easily actuated by electromagnetic force induced by magnetic potential gradient between planar coils and the magnet. However, this opened loop system can not realize its precise motion control, because of the characteristic deviation of each device, aged deterioration and thermal behavior. This report describes motion monitoring of MEMS actuators with electromagnetic induction for precise motion control. We have confirmed that the theory of motion sensing, we have constructed, agreed with experimental results approximately.

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