A polarized liquid metal worm squeezing across a localized irregular gap

Abstract

The deformation capability of a robot has been a long-term research interest in robotic fields along with developing its controllability and adaptability. So far, many different structural designs and materials had been created to build a flexible and compliant robot. Here, we demonstrate a series of highly deformable locomotions overcoming sharp corner or small gap via EGaIn liquid metal materials, which we dubbed “liquid metal worm.” The worm can be controlled by exterior voltages and can veer in a loop channel. Besides, it can narrow and fit through a highly confined gap five times thinner than its own size and return to its original shape and movability. The size of the worm can also be adjusted with different volumes of liquid metal, which varies from ∼0.1 mL to ∼1 mL. In addition, other solid functional structures or modified particles can be mounted according to previous research. Several phenomena regarding reconfigurational reversing of the moving direction due to metal droplet morphology were disclosed with the interpreted mechanism. The worm realized a biomimetic deformative characteristic and may have profound implications in other fields such as vascular robots and microfluidics. It is expected that the present work could contribute to the development of soft robots and their miniaturization in the coming future.