Control of Bioconvection and It's Application for Mechanical System : 1st Report Basic Effects of Electrical Field on Bioconvection

Abstract

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, "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.