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Study lead author Saba Firouznia, Research Associate at the University of Bristol Soft Robotics Lab, holding the robot butterfly in palm of her hand.
Photo Credit: Saba Firouznia
Scientific Frontline: Extended "At a Glance" Summary: Liquid-Metal Magnetohydrodynamic (LIMA) Pump for Soft Robotics
The Core Concept: The LIMA pump is a pea-sized, lightweight fluid pump that utilizes liquid metal to convert electrical energy into fluid motion. It serves as an efficient, ultra-compact power source for next-generation soft robotics and adaptive wearable materials.
Key Distinction/Mechanism: Unlike traditional soft robotics powered by bulky compressors or rigid, high-voltage components, the LIMA pump weighs just 0.2 grams and operates on less than 0.1 volts. It functions by passing an electric current through a liquid metal droplet in the presence of a magnetic field; this generates a Lorentz force that moves the droplet back and forth, displacing the surrounding fluid to create a powerful pumping action.
Major Frameworks/Components:
- Magnetohydrodynamics (MHD): The study of the magnetic properties and behavior of electrically conducting fluids.
- Lorentz Force Generation: The underlying physical mechanism where electrical and magnetic fields interact to produce mechanical motion within the liquid metal droplet.
- Intrinsic Liquid Metal Properties: Utilization of the material's high electrical conductivity, high surface tension, deformability, and low resistance to motion to operate at millivolt levels.
- Multi-Functional Fluidic Networks: The system's ability to transfer hydraulic energy, chemical energy, and information signals simultaneously.
Branch of Science: Soft Robotics, Electromechanical Engineering, Fluid Dynamics, and Magnetohydrodynamics.
Future Application: The technology has broad potential for wearable tech and medical devices, including haptic VR gloves, lab-on-a-chip diagnostics, robotic clothing, smart bandages, environmental sampling actuators, and edible robots. Prototypes already include robotic butterfly wings and haptic fingertip pouches.
Why It Matters: The LIMA pump effectively eliminates the stiff bulkiness that has historically limited robotic mobility. By acting as a soft, artificial "heart" that combines pumping, signaling, and energy transfer into a single low-voltage platform, it enables the creation of highly portable, autonomous, and agile soft robots.
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| Close-up of the robot butterfly featuring the feather-light LIMA pump. Photo Credit: Saba Firouznia |
Engineers have invented an ingenious liquid-metal pump that could make future soft robotics and wearable devices much more portable and agile.
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 robotic 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 color-changing bracelet, and a haptic fingertip pouch connected to an adjustable wristband that 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, a 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 micropumps for robotic clothing to tiny actuators for environmental sampling. The sky really is the limit.”
The liquid-metal magnetohydrodynamic (LIMA) pump is featherlight, weighing just 0.2 g, and runs at less than 0.1 V, yet it 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.
Firouznia 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-subvolt levels while still generating useful pressures and flow rates for soft robotic movement.”
Because 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 toward more portable, autonomous, and multifunctional soft robots.
Study coauthor 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 is head of the Soft Robotics Research Group—added, “Crucially, the LIMA pump acts as a soft, compact ‘heart’ for robotic systems, combining pumping, signaling, 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.”
Published in journal: Nature Communications
Title: A flexible liquid metal magnetohydrodynamic pump for soft robotic systems
Authors: Saba Firouznia, Christian Romero, Ciqun Xu, Lihaoya Tan, Andrew Stinchcombe, Martin Garrad, Andrew Conn, Hemma Philamore, and Jonathan Rossiter
Source/Credit: University of Bristol
Edited by: Scientific Frontline
Reference Number: eng052726_01