PRESS your ear against your biceps, bend your arm and listen. The gurgling murmurs you can hear, made by muscle fibres as they move against each other, could provide a way for people to control prosthetic hands more easily.
In a lab at Imperial College London, PhD student Sam Wilson straps two matchbox-sized listening devices to my arm just below the elbow. I clench my hand and the robotic hand resting on the table makes a fist. I try using it to grab a soft cube. It escapes the hand’s grip on my first few attempts, but with a bit of practice it’s easy.
Wilson and his supervisorare designing new ways for the human body to control prostheses. Typically, these use electrodes on the surface of the skin to pick up electrical activity in the arm muscles, called myoelectricity.
Vaidyanathan had the idea to develop different sensors for controlling prostheses when a colleague told him about a man who split his time between India and the UK, and claimed that his prosthetic hand knew when it was in India and stopped working. His doctors were baffled. Eventually they realised that the warmer Indian climate was the culprit: sweat was interfering with the electrodes that sense his muscle movements. It’s a common problem with such prostheses: they don’t work consistently for long periods.
“We wondered if there was a more robust way of detecting muscle activity and harnessing it for robotic control,” says Vaidyanathan.
He had been using accelerometers to sense muscle movements, but found that the gurgling muscle fibres were interfering with …
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