The breakthrough, led by the University of Bristol and published in the journal Nature Communications, presents a low-voltage power source with the potential to transform robotic systems in a wide range of applications from robotics legs to haptic gloves used in medical and industrial settings.
The researchers have demonstrated the varied uses of this innovative technique by creating three prototypes including robotic butterfly wings, a colour-changing bracelet, and a haptic fingertip pouch connected to an adjustable wristband which squeezes to simulate natural tactile sensations.
Current technologies are powered by bulky compressors or rigid pumps, which limit mobility and flexibility. The small lightweight soft pump – the size of a pea – is powered by liquid-metal, which converts electrical energy into fluid motion creating an efficient, compact power source for next-generation soft robots and adaptive materials such as medical devices and wearable interfaces for virtual reality.
Study lead author Saba Firouznia, Research Associate at the University of Bristol Soft Robotics Lab, said: "It's a really exciting development, which overcomes the existing barriers of stiff bulkiness and offers something miniature, portable and more adaptable. These enhanced characteristics mean it could be deployed to better effect in existing uses like lab-on-a-chip devices for disease diagnosis and also with new ones, ranging from micro pumps for robotic clothing to tiny actuators environmental sampling. The sky really is the limit."
The liquid-metal magnetohydrodynamic (LIMA) pump is feather-light, weighing just 0.2g, and runs at less than 0.1V yet has the potential to outperform existing soft pumps and even some commercial pumps used for fluid transport and hydraulics.
When an electric current passes through the liquid metal droplet in the presence of a magnetic field, a force – called the Lorentz force – is generated. This moves the droplet back and forth, displacing surrounding fluid and creating a pumping action.
Saba explained: "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. 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."
As the pump can transfer not only hydraulic energy, but also chemical energy and information signals through soft fluidic networks, it has powerful integration potential and offers a route towards more portable, autonomous, and multi-functional soft robots.
Study co-author Jonathan Rossiter, Professor of Robotics at the University of Bristol who is famed for developing a pair of pioneering robotic trousers dubbed 'the right trousers' and head of the Soft Robotics Research Group, added: "Crucially, the LIMA pump acts as a soft, compact "heart" for robotic systems, combining pumping, signalling, and energy transfer in a single low-voltage platform. Further research is now underway to further develop the technology and explore how it can help in a whole host of different situations, from smart bandages to edible robots."
Paper
'A flexible liquid metal magnetohydrodynamic pump for soft robotic systems' by Saba Firouznia et al. in Nature Communications
