Biologically Inspired Miniature Water Strider Robot

Recent biological studies on water strider insects revealed the detailed mechanism of their staying and walking on water. While macro scale bodies use buoyancy to stay on water, these very light and small insects balance their weight using repulsive surface tension forces where the insect legs are covered with hydrophobic micro-hairs. Utilizing the unique scaling advantage of these insects, this paper proposes a biologically inspired miniature micro-robot walking on water with a similar principle. The paper focuses on understanding physical characteristics of the insect and designing a robot that mimics the insect's movement. Highly hydrophobic Teflon coated wires are used for the legs to take advantage of surface tension force, and the robot body is made of carbon fibers for minimal weight. A T-shaped actuation mechanism with three PZT-5H based unimorph actuators is utilized to move the side legs of the robot independently for controlled locomotion. Kinematics and dynamic properties of the robot prototype are analyzed and compared with the experimental results. The tethered robot can successfully move forward, backward and can also make turns. Maximum speed of the robot in forward motion is 2.3 cm/s. In the future, environmental monitoring applications on dams, lakes, sea, etc. would become possible using a network of these robots with miniature sensors, an on-board power source and electronics.