Water strider robots with microfabricated hydrophobic legs

This paper discusses biomimetic water strider robots that have microfabricated hydrophobic legs. Various kinds of supporting legs with hydrophobic microstructures on their surfaces were developed using MEMS (micro electromechanical systems) techniques. The lift and pull-off forces of these supporting legs were analyzed theoretically and then measured. The experimental results were in good agreement with the calculations. Two different mechanisms for autonomous water strider robots were developed. One robot with twelve microfabricated legs driven by a vibration motor successfully moved on a water surface and also made left/right turns by exploiting differences in the resonant frequencies of the legs. The other robot, with six microstructured legs, moved on water through elliptical motion of its middle legs, which is similar to the motion of actual water striders.