Control of bioconvection and it's application for mechanical system: (2nd report, pitch optimization of electrodes array and driving of mechanical system by controlled bioconvection

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 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 0.5 mm and that the gap between electrodes is 0.2 mm. 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 0.14 mm/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 70-150 s.