Abstract
This study investigates the possibility whether protozoa can be treated as a living 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.
