Small universal mechanical module driven by a liquid metal droplet.

Gallium-based liquid metal droplets (LMDs) from micro-electromechanical systems (MEMS) have gained much attention due to their precise and sensitive controllability under an electric field. Considerable research progress has been made in the field of actuators by taking advantage of the continuous electrowetting (CEW) present within the solution. However, the motion generated is confined within the specific liquid environment and is lacking a way to transmit its motion outwardly, which undoubtedly serves as the greatest obstacle restricting any further development. Therefore, a driving module is proposed to generate rotational motion outside the solution for universality. Its performance can be easily tuned by adjusting the applied voltage. As an example of further application, the module is designed in the form of a pump that realizes the continuous/intermittent propulsion to mimic the veins/arteries of the human body without the problem in the previous LMD-based pumps. The feasibility of this pump in the on-chip in vitro analysis is proved by preparing a dynamic cell culture to simulate the movement of biofluids within human bodies. This study proposes an optional solution with an LMD-based motor for generating rotational motion and to expand current research on soft materials in actuators.