High-speed interfacial flight of an insect-scale robot

Several insect species are able to locomote across the air-water interface by leveraging surface tension to remain above the water surface. A subset of these insects, such as the stonefly and waterlily beetle, flap their wings to actively move around the two dimensional surface — a locomotion strategy referred to as interfacial flight. Here, we present an insect-scale robot, the γ-bot, inspired by these interfacial fliers. The robot is comprised of a flapping-wing vehicle that generates a thrust force parallel to the water surface, and three passive legs utilize surface tension to support the body mass and maintain contact with the air-water interface. We developed and validated a simple model to characterize the drag forces acting on the vehicle and estimate the robot’s velocity. This 112 mg robot can reach maximum velocities of 0.9 ms
⁻¹
(corresponding to 15 BLs
⁻¹
) and can initiate both left and right turns, demonstrating high maneuverability along the air-water interface. In addition, the robot can carry an additional 419 mg, enabling future sensing, control, and power autonomous operation.