Researchers at the University of New South Wales (UNSW) in Sydney have developed what they describe as the “world’s first motor that spins using a droplet of liquid metal”, a breakthrough that could open new possibilities for soft robotics, flexible electronics and medical devices.
According to a blog published by UNSW on January 19, the experimental motor produces rotation without the rigid components typically used in conventional designs, such as coils or magnets. Instead, it relies on swirling flows generated inside a droplet of liquid metal that is suspended in a salt solution and exposed to an electric field. A small copper paddle placed within the droplet is carried by these internal flows, creating continuous rotational motion.
According to the research team, the device, known as a liquid metal droplet rotary paddle motor, represents a fundamentally different approach to generating mechanical motion. The motor has reached speeds of up to 320 revolutions per minute, setting a new performance benchmark for liquid metal–based actuators.
“This is a completely new way to create motion,” said Dr Priyank Kumar, who supervised the project, noting that the design produces rotation by harnessing the flow of liquid metal itself rather than relying on solid moving parts. He added that the approach demonstrates how simple, flowing materials can be used to drive rotation in compact and flexible systems.
Electric motors underpin a wide range of everyday technologies, from smartphones and laptops to household appliances and industrial machinery. Because so many devices depend on rotary motion, researchers say that alternative motor designs could have broad implications for future machines, particularly in areas where traditional rigid components are impractical, states the blog.
The liquid metal motor could be especially useful in soft robotics, a field focused on machines that can bend, stretch and operate in confined or irregular spaces. Rigid gears and shafts often limit such designs, whereas a motor that is itself flexible could enable new forms of movement and functionality.
“Imagine a tiny robot moving through narrow, irregular spaces inside the human body, powered by motors that are soft and flexible rather than hard and fragile,” said Professor Kourosh Kalantar-Zadeh of the University of Sydney, a collaborator on the research.
The motor was developed by PhD student Richard Fuchs, who compared its operation to a miniature waterwheel, with flowing liquid metal pushing the copper paddles in much the same way that water drives a wheel.
Beyond robotics, the researchers say the technology could find applications in flexible electronics, microfluidic systems and biomedical implants, where compact and adaptable motion is required in delicate environments.
