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伊東, 明俊 ; 樋田, 英紀 ; 早乙女, 康典
概要:
application/pdf<br />Journal Article<br />Bioconvection is a convection that is autonomously generated by the high-density suspension of some kinds of microorganisms. This study aims to apply the bioconvection to a power source of
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a micro mechanical system. For that purpose, the authors previously reported that a downward flow of bioconvection could be controlled by changing the electrical field. The construction of the experimental pool is that the bottom surface is covered with a positive electrode. A negative electrodes array is also installed at the top of the pool. In this paper, application system of electrical field was renovated to allow the application of any desired voltage to each electrode. Image processing system is installed to detect the position of the downward flow automatically. The configuration of the electrodes array is optimized to the shape that the width is 0.5mm and that the gap between electrodes is 0.2mm. Gaussian distribution is used to apply the electrical field by using plural electrodes. It was succeeded to locate the downward flow to any position. The maximum moving speed of downward flow is 0.14mm/s. As an example of the mechanical application, it was also succeeded to drive a small seesaw automatically by the controlled downward flow with the reciprocating cycle 70-150s.
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伊東, 明俊 ; 樋田, 英紀 ; 早乙女, 康典
概要:
application/pdf<br />Journal Article<br />This study investigates how to control the stream of bioconvection. Bioconvection is a phenomenon that is autonomously generated by the high density culture media of microorganisms. In this study,
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"negative galvano-taxis" of microorganisms are used to control the downward stream of bioconvection. For that purpose, an array of 15 negative electrodes is installed at the top of the observation pool. The basic effects of electrical field on bioconvection was investigated. The result shows that the status of bioconvection classifies three different regions by the strength of electrical field. The lower area is "natural convection region" in which bioconvection is not changed by electrical field. Middle area is "convection control region" in which down flow stream near the negative electrode is brought to just under the negative electrode. The higher area is "forced convection region" in which the down flow stream that is generated under negative electrode dominates whole of convection stream and original bioconvection stream is disappeared. This controlled downward flow has a possibility as a driving source for micro fluid machines.
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伊東, 明俊 ; 小林, 琢 ; 早乙女, 康典
概要:
application/pdf<br />Journal Article<br />This study investigates the possibility whether protozoa can be treated as a l
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iving micro manipulator/actuator or not. Motion control of protozoa was made by using the negative galvanotaxis. In the previous study, it was succeeded to control the paramecium along figure '8'. Its controllability, however, has problems about speed control, rapid turn and position accuracy. Therefore, this paper first investigates the application of pulse width modulation method for the control of paramecium's swimming speed. However, the results show that the application of the pulse electric field causes the strange reaction such as rotation, zigzag swimming, etc. Next, rapid stopping phenomenon of paramecium's swimming by the sudden stop of electrical field is investigated to improve the rapid turning ability of paramecium's swimming. To adopt this method to the automatic motion control program, paramecium can be controlled along any shaped guide route. Paramecium's generating force is also measured by pushing the small object by controlled paramecium. It is estimated about 2.7×10^<-8> N. For an example of the micro mechanical application, the micro impeller (φ 0.5 mm) is rotated by paramecium. These results show that micro mechano-bio-fusion system can be constructed by using protozoa.
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秦, 誠一 ; 山田, 典弘 ; 早乙女, 康典 ; 井上, 明久 ; 下河辺, 明
概要:
application/pdf<br />Journal Article<br />Amorphous alloys with the wide supercooled liquid region are called metallic g
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lasseS. In the supercooled liquid state, the metallic glasses exhibit superplasticity, which suggests the possibilities of forming the metallic glasses into various intricate shapes. In this paper, formability of two types of Zr based metallic glass; Zr_<75>Cu_<19>Al_6 and Zr_<55>Cu_<30>Al_<10>Ni_5 (atomic%) are examined in the supercooled liquid state. The example metallic glasses showed superplasticity under compressire stress and high thermal stability in the supercooled liquid state. Furthermore, forming accuracy of the example metallic glasses was better than one micrometer. As the application of such precise forming, a concave mirror with a l0 mm diameter was formed. The profile error of the mirror was 0.5 μm and the surface roughness (Rmax), 90 nm. This superplastic forming of the Zr based metallic glasses is expected to be used for the production of various components of high precision and intricate shape.
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