ミジンコ類の光走性を利用した行動制御とその応用

―‘Ｙ－Ｗｉｎｇ’式作業用具の開発と，それを利用した搬送効率の改善―

抄録

We have been investigating how to use protists as living micromachines by controlling their behaviors using their taxes. Because of the difficulty of attaching tools on protist such as Paramecium, we are now investigating the applicability of the water flea for bio-micromachine. Water fleas are small crustacean and they wear outer shells as external skeletons. Therefore, we can attach operational tools on the shell by chemical adhesion. In our former studies, we succeeded to control Daphnia magna's motion by illuminating the blue LED light to guide the swimming direction using their strong positive phototaxis. We tried to enhance the object pushing ability of Daphnia by the attaching twin bending needles type operational tool. However, the controllability while transporting the object was very bad and hence the total transportation time was not improved comparing to transport by Daphnia only. In this study, we tried estimate the effect of the attaching position and the size of the polypropylene rod type operational tool on the Daphnia's back to the Daphnia's swimming performance. The results showed that it was important to match the rod angle to the Daphnia's body axis (Roll and Yaw). To set the distance of the Daphnia's body center and the center of gravity of the attaching tool as short as possible is very important to improve the Daphnia's maneuverability. We developed a new operation tool called ‘Y-wing' whose structure was that a v shaped vending polypropylene rod was attached on a polypropylene straight rod. By using this new operation tool, LED movable type new motion control pool and new control program, the object transportation time along star-shaped target route was drastically reduced to one-fifth comparing to the transportation by Daphnia only. It means that the operation tool enhance the Daphnia's object transportation ability.