Muscle radar unlocks potential for future robotic limbs

New non-invasive sensors that measure muscle forces have been developed by University of Queensland researchers, unlocking new possibilities for wearable robotic mobility devices.  

Ultra-wideband radar sensors measure the electromagnetic changes in muscles as they contract, allowing researchers to collect data in a way that’s never been done before.  

PhD candidate Christopher Bird, who led the research, said the sensors have the potential for several applications, including robotic or prosthetic devices. 

“Up until now there hasn’t been a way to accurately measure the mechanical forces being produced by muscles when they contract, without invasive procedures,’’ Mr Bird said. 

“When we use a robotic or prosthetic device to help people move, say in motor neuron disease or ageing, we want to know when that device should give the person assistance and how much it should give. 

“But our current exoskeletons typically rely on external measures to prescribe when and what support is needed. 

“The results were better than I had hoped for.” 

 

Ultra-wideband radar antennas, which sit on top of the skin, send electromagnetic pulses into the muscles and record how the transmitted and reflected signals change as the muscle contracts. 

Associate Professor Taylor Dick from UQ’s School of Biomedical Sciences, said having accurate measurements of muscle forces opens exciting possibilities for rehabilitation, injury prevention and recovery, and aged care. 

“In some rehabilitation scenarios, electrical currents are used to stimulate muscles in people who have lost voluntary control, but muscle can fatigue quickly and tissue can be damaged,” Dr Dick said. 

“Until now, there’s been no tool to measure how or when that damage will occur.” 

“There are enormous benefits with this technology – it could help injured athletes accurately determine the best time to return to training with a lower risk of re-injury, and clinicians and patients can be better informed before surgical or rehabilitative decisions are made.’’ 

The goal now is to eventually have the sensors able to measure forces in real time, allowing them to be used as an input for assistive devices.

“Having a real-time sensor calculating the forces being produced under the skin, telling a device when it should be providing assistance, that’s an exciting development,” Mr Bird said. 

Read the research in Science Robotics. 

Collaboration and acknowledgements