A tiny flexible magnetohydrodynamic pump capable of powering soft robots has been developed by a team from the University of Bristol.

According to its developers, the tiny pump, which is roughly the size of a pea, is powered by liquid metal that converts electrical energy into fluid motion. This reportedly produces an efficient, compact power source appropriate for robot and adaptive material applications including medical devices and wearable interfaces for virtual reality.

Source: Saba Firouznia

With the potential to surpass existing soft pumps and, possibly, some commercial pumps used in fluid transport and hydraulics applications, the so-called liquid-metal magnetohydrodynamic (LIMA) pump weighs roughly 0.2 g and operates at less than 0.1 V.

The developers explained that as an electric current passes through the liquid metal droplet in the presence of a magnetic field, a Lorentz force is produced that moves the droplet back and forth, thus displacing surrounding fluid and triggering a pumping action.

“Unlike conventional soft pumps, which often rely on bulky, rigid, or high-voltage components, LIMA uses the intrinsic properties of liquid metal: high electrical conductivity, high surface tension, deformability, and low resistance to motion,” the team explained. “These properties allow the pump to operate at millivolt-to-sub-volt levels while still generating useful pressures and flow rates for soft robotic movement.”

Three prototypes were developed by the Bristol team to demonstrate the pump: robotic butterfly wings, a color-changing bracelet and a haptic fingertip pouch connected to an adjustable wristband that squeezes to mimic natural tactile sensations.

The team suggests that the pump can transmit signals while delivering chemical and hydraulic energy, allowing for smaller, portable and multifunctional soft robots for applications that range from medical diagnostics to robotic clothing and environmental sensing.

An article detailing the pump, “A flexible liquid metal magnetohydrodynamic pump for soft robotic systems,” appears in the journal Nature Communications.