Abstract
In this paper, we investigated how to drive a waterwheel by position controlled downward flow of the Euglena's bioconvection. The position of the downward flow was controlled by applying Euglena's phototaxis to the scanning blue laser beam. Formally, we succeeded to drive a seesaw by electrically position controlled downward flow of the Tetrahymena's bioconvection. In this paper, we aimed to reproduce the laser control version of this seesaw driving by using Euglena. We have already confirmed that if the experiment is done in the horizontal planar pool, we could make any shapes of Euglena group and we could also assemble simple mechanical parts by pushing the part by Euglena group. In the case of the vertical planar pool, however, it is difficult to produce strong downward flow by irradiating laser from side direction. In this study, therefore, we first investigated the basic conditions to control the bioconvection downward flow by irradiating the scanning blue laser from the top surface. The results, although it succeeded in the drive of 180° rotation, showed that to generate and to control a steady bioconvection downward flow was very difficult due to the Euglena's poor swimming performance. We reduced the friction of the waterwheel and introduce the top surface irradiation to guide the Euglena located at around the pool side into the bioconvection flow. By using this scheme, we are able to make rotate the waterwheel over 180deg. We also tried to drive 20mm span seesaw that we could not reciprocate it by the downward flow generated by the laser irradiation from side direction. The result showed that the seesaw could drive over 13 reciprocation by using the downward flow generated by the laser irradiation from the top surface.
