Researchers at UNSW have developed a radically new type of motor that generates rotation not through rigid components, but via the internal flow of a droplet of liquid metal.
The device, known as a liquid metal droplet rotary paddle motor, could have wide-ranging implications for soft robotics, flexible electronics and medical technologies, where traditional motors are often too bulky or rigid to be effective.
Unlike conventional motors that rely on coils, magnets and solid shafts, the new motor operates by embedding a droplet of liquid metal in a salt solution and exposing it to an electric field. This field induces swirling flows within the droplet itself. A small copper paddle placed inside the liquid metal is carried along by these internal currents, producing rotational motion.
“This is a completely new way to create motion,” said Dr Priyank Kumar, who supervised the project and is corresponding author of a paper published in npj Flexible Electronics.
“We’re harnessing the flow of liquid metal itself to produce rotation, without any traditional moving parts. It’s simple, compact, and inherently flexible.
“Reaching speeds of 320 revolutions per minute, our motor sets a new benchmark for liquid metal actuators. It proves that simple, flowing metals can drive rotation and opens the door to an entirely new class of motors.”
Rotary motors are embedded in everyday life, often unnoticed. They power smartphone vibrations, laptop cooling fans and camera focus systems, and are central to everything from washing machines to drones. Because so many technologies depend on spinning motion, any fundamental shift in how motors are designed has the potential to reshape products across consumer, industrial and medical fields.
The liquid metal motor may be particularly valuable in environments where rigid mechanical components are impractical. Soft robotics, for example, often require machines that can bend, stretch or squeeze through confined spaces, something that traditional gears and shafts struggle to achieve.
“Imagine a tiny robot that can move through narrow, irregular spaces inside the human body, powered by motors that are soft and flexible rather than hard and fragile,” said University of Sydney Professor Kourosh Kalantar-Zadeh, a collaborator on the project. “That’s the kind of future this technology points to.”
The motor was developed by PhD student Richard Fuchs, who said its appeal lies in its straightforward design.
“The beauty of this design is its simplicity, it’s like a miniature waterwheel,” he said. “Similar to how flowing water pushes the blades of the wheel, the swirling liquid metal pushes the copper paddles.”
Beyond robotics, the researchers believe the technology could enable new forms of motion in flexible electronics, microfluidic systems and biomedical implants, where compact, self-contained and adaptable motors are essential. By replacing rigid machinery with flowing metal, engineers may be able to design devices that were previously out of reach.
