Control of bioconvection and its mechanical application

A high-density culture medium of protozoa autonomously generates bioconvection because of its property of negative gravi-taxis and of its density heavier than the culture medium. Many species of protozoa also have the property of negative galvanotaxis. Therefore, this study aims to control bioconvection by applying an electrical field and to use bioconvection for the energy source or the mechanical power source. In the study, downward flow of bio-convection was controlled by the negative electrode allay installed on the top plate. The results show that the position of the downward flow can be controlled by this system. As an example of the mechanical application, a small seesaw was continuously driven by the controlled downward flow.