A liquid metal droplet rotary paddle motor

Traditional rotary motors have been developed using a variety of technologies. Electrochemically fluidic motors based on liquid metals offer unique potential advantages to the field of rotary motors. Current designs, however, are limited in rotational speed due to suboptimal extraction of mechanical motion from the liquid metal. Here, we present an electrochemically driven liquid metal rotary motor that is conceptually distinct from previous approaches by incorporating a paddle directly inserted inside the liquid metal droplet. This design, driven by pulsed electric signals, takes advantage of the internal vortices of the droplet to directly generate rotation, achieving maximum rotational speeds of 320 rpm. By directly coupling the paddle to the internal flow dynamics, this work demonstrates a more efficient and practical method for liquid metal-based actuation in an electrochemical setting. Such a system has potential applications in microfluidics and soft systems and introduces a new conceptual approach to rotary motor design.