We synthesized a micro lens array with variable focal length by micromachining a gel which expands and contracts in response to pH stimulation. The silicone template was made as a mold for the lens array. Acrylic acid was polymerized on the mold and the polymerized gel was used as the lens array. The micro lens swelled and shrunk in response to pH change, The focal length change was investigated using the same composition of poly(acrylic acid) gel. In the future, we will create a device which can improve image processing efficiency by adjusting the lens focal length only in the region corresponding to the particular image to be sharpened among the images already captured on the light-receiving surface.

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We have developed an inexpensive temperature controlled microreactor(HMR: Hybrid Microreactor) for protein synthesis. The structure of the microreactor is a sandwich of glass-based chip and PDMS(polydimethylsiloxane) chip. The thermo control system, which is composed of a heater and a temperature sensor, is fabricated with an ITO (Indium Tin Oxide) resistive material on a glass substrate by ordinary microfabrication method based on photolithography and etching techniques. The reactor chamber and flow channels are fabricated by micromolding of PDMS. Since one can use thermo control system repeatedly by replacing only the easily-fabricated and low-cost PDMS reactor chamber, this microreactor is quite cost effective. As a demonstration of the microreactor, a DNA template of a GFP (Green Fluorescent Protein) is transcribed and translated using cell-free extract prepared from Escherichia coli. As a result, protein synthesis in this device was performed successfully.

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Polymer microchips, possessing a minute channel(s) on the substrate with its width and depth of 100 and 20μm, respectively, were fabricated on the basis of photolithography and imprinting methods. Microelectrodes were also introduced successfully onto the microchannels by applying vacuum deposition and lithography/etching of metal thin films. Fabricated polymer microchannel chips were demonstrated to be potential enough for various chemical applications.

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The oxyradical production by leukocytes is crucial for killing invading bacteria, while it has been widely discussed as a tissue injuring factor. However, it is still unclear, probably because of lack of simple and reliable measurement methods, to what extent it varies among different subjects and either to what extent it is affected by environmental factors including diet. Meanwhile, our previous studies have shown usefulness of parallel arrays of many identical capillary-size channels for the measurement of rheological or mechanical properties of blood and other cells, Our flow measurement system is now commercially available as MC-FAN (Micro Channel array Flow ANalyzer). The aim of the present study is to describe an application of MC-FAN to the measurement of the oxyradical production using chemiluminescence for leukocytes in whole blood. Fresh heparinized whole blood was caused to flow through a microchannel array (width 7μm, length 30μm, depth 4.5μm, and number 8736) under a 20cmH₂O suction with the addition of Salmonella typhimurium cells (2×10⁷CFU/ml) or S. typhimurium lipopolysaccharides (100ng/ml) and luminol (200μM). When 100μl passed, the flow was ceased and leukocytes lodged in the microchannel array were subjected to the photoemission measurement by a VIM camera system or a photomultiplier-DC amplifier system. The passage depth (4.5μm) under the glass plate covering the microchannel array allows only single cells in the depth direction; this explains why photons emitted in the observation direction are not absorbed by red cells. In addition, the microchannel array concentrated leukocytes there and hence gave a sufficient number of leukocytes in the measurable area, i.e., a sufficient intensity of photoemission thatt allowed a real time measurement, Thus, a simpler and more reliable method has been established. An unexpectedly large variation in the oxyradical production by leukocytes was observed among healthy subjects.

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Molecular biology is moving rapidly towards the stage of functional genomics in which rapid preparations of expressed messages (mRNA) will be required. If a DNA library is constructed on a solid support (DNA probe array) and any kind of expressed messages can be individually recovered from the probe array, DNA probe array will become a very useful method. Consequently, we developed a DNA preparation method using a DNA probe array that utilizes photo-thermal denaturation to recover specific DNA. The protocol for preparing DNA probe array was investigated to realize the stable immobilization of DNA probes on the surface of solid support. We used a glass plate coated with Cr (5-10nm thick). The Cr surface was modified with 3-glysidoxypropyltrimethoxysilane to introduce active residues that can couple with amino residues at the 5' termini of DNA probes. The Cr surface acts as a photo-thermal transducer. The preparation method of DNA uses infrared (1053-nm) laser irradiation to thermally denature and release DNA immobilized in a specific area of a DNA probe array. Different DNA fragments fixed in place on the DNA probe array could be separately recovered. There were enough quantities of recovered DNA that can be amplified by using PCR.

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An electrochemical array, ECA, for DNA analysis was designed and constructed as a microarray for the next generation by integrating DNA sensing multiple electrodes. Probe DNAs were immobilized on 25 electrodes of an ECA chip and allowed to detect the target DNA with ferrocenylnaphthalene diimide (FND) as an indicator. As an application example of this system for single nucleotide polymorphisms (SNPs) analysis, a DNA mismatch on the cancer repression gene p53 was successfully analyzed with 88% precision.

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In this paper, we describe how to improve the resolution of an absolute type displacement sensor utilizing standing wave on a transmission line. This sensor is based on the phenomenon that the node of standing wave is produced every half-wavelength on the transmission line driven by a signal source. We show theoretically that the resolution is dependent on the frequency of the signal source and establish experimentally that the resolution also depends on the frequency jitter of it chiefly.
By our experiments, we have been able to confirm that it is possible to improve the resolution by using the signal source with higher frequency and lower frequency jitter. Finally, we have confirmed that the resolution of this sensor is improved to 4μm, i.e., 1ppm in the displacement of 4m.

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A new type of a temperature-compensated sensor system, which detects dissociation heat caused by ozone decomposition, is suggested. The detection principle is almost identical to that of a catalytic combustion (pellister-type) sensor except that the suggested sensor does not utilize catalytic materials. A sensing device with catalyst and a compensating device without catalyst have been utilized at the same operating temperature in a conventional catalytic combustion sensor to form a bridge configuration. In the proposed sensor system, sensing devices of identical characteristics without any catalysts are adapted for both sensing and compensating devices. However the operating temperatures of the two devices are different. The sensing device is operated well above the decomposition temperature of ozone, whereas the operating temperature of the compensating device is below the decomposition temperature. Signals of the two devices are amplified with the corresponding gains to cancel the temperature dependences of the two devices, when ozone is not present. Ozone decomposes by itself upon contact with the sensing device owing to thermal decomposition and generates the heat. The thermal decomposition does not take place at the compensating device.

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In this paper, we propose SR etching as a new approach to fabricate 3D microstructures of PTFE. SR etching is a process of TIEGA that fabricates microstructures using polymers like PTFE by etching directly in a vacuum using SR light. The etching rate is on the order of 6-100μm/min. SR beam direct writing was possible by SR light through a pinhole that fabricated 3D microstructures of PTFE combining a scanning stage with a high degree of freedom. 3D micromachining of PTFE by SR beam direct writing with atmospheric pressure as an exposure condition is thought to be desirable from the practical point of view. So, we approached SR etching under 2 conditions; in a vacuum and under He at 1 atm. As a result, corn shape PTFE microstructure was fabricated with a turning radius of 300μm and a depth of 1mm achieved.

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This paper describes the first study on a polycrystalline Si (poly-Si) nano wire from the viewpoint of MEMS mechanical sensor application. In order to confirm an ability of the poly-Si nano wire piezoresistor as a sensing element of a mechanical sensor, current-voltage (I-V) characteristics and the piezoresistive effect were investigated. The poly-Si nano wire piezoresistor, whose thickness is 32nm and width is 53nm, was fabricated by the combination of the electron beam (EB) direct writing and RIE. A remarkable phenomenon was observed. The longitudinal piezoresistive coefficient π_l of the nano wire piezoresistor increased with a decrease in the cross section area, while the transverse piezoresistive coefficient π_l was approximately zero and invariant despite variation of the cross section area. The maximum value of the longitudinal piezoresistive coefficient π_l of the nano wire piezoresistor was 22×10^-5(1/MPa) at impurity concentration N=5×10¹⁹ (cm^-3).

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It has been noticed recently that there is a possibility of elution of chemical substances from packages of foods. The chemicals act as harmful substances such as environmental hormones for biological bodies at very low concentration. It is therefore necessary to develop a sensing device, which can detect such substances easily and quickly. The purpose of the present study is high sensitive measurement of environmental hormones using electrode polarity controlling method. The responding ability of the polarity-controlled sensor covers various chemicals from electrolytes to nonelectrolytes and from hydrophilic to hydrophobic substances. As a result, we could sensitively detect bisphenol-A at about 50ppb and dibutyl phthalate at about 3ppb, and the sensor could distinguish such chemicals from ordinary taste substances.

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Magnetic rotational wings that rotate in an alternating magnetic field were fabricated and analyzed. The rotational wings are composed of the rectangular-shaped magnetic wings and a thin rod in the center that acts as the axis of rotation. When the alternating magnetic field and the initial rotation are applied, the rotational wings keep on rotating at the same frequency as the magnetic field. The magnetization of the wings, the magnetic torque exerted on the wings and the resistance of the air are calculated and the rotation of the wings is simulated. When the thrust generated by the wings overcomes the weight of their own, the wings take off along the guide. The 165-mg 0.9-mm-long micro-rotational wings fabricated by micromachine technology succeeded in taking off at 570Hz. The non-dimensional number C_rw was introduced to represent the characteristics of the rotational wings. C_rw increases, as the wing length decreases. C_rw of around 1mm long rotational wings was estimated to be 2.

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