Most advanced robots are machines made from rigid materials, like metals and plastics. Soft robots exist, but they’re typically controlled by external air compressors and pumps used to inflate balloon-like structures. Some require voltages that are ten times higher than a household electrical socket to produce a current that simulates movement in stretchy material.
“It’s a little bit scary to use — for example, if you want to put it inside a robot for childcare or elderly care,” said Miriyev.
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The material Miriyev and his colleagues developed doesn’t require outside pumps or other external equipment and requires around 10 volts to work.
To make the artificial muscle, the scientists mixed ethanol — a common ingredient used in everything from alcoholic beverages to cleaning products — with liquid silicone rubber. After mixing, microscopic bubbles of ethanol disperse throughout the rubber, and after it cures, the bubbles settle into tiny pockets within the rubber.
By embedding a very thin wire into the matrix of the rubber, the researchers were able to direct a low-voltage current through the material, heating it to 78.4 degrees Celsius (166.6 degrees Fahrenheit), the boiling temperature of ethanol. The boiling increases the volume of the ethanol bubbles — and expands the synthetic muscle.
“We managed to get a straightforward solution for a very tricky, intricate, and challenging [problem],” said Miriyev.
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Miriyev said that he and his colleagues want to turn the muscle into a sensor so a computer can monitor how much the muscle has moved and even use machine learning to predict how much it needs to move to pick a tomato, for example.
“Then,” he said, “we can say we have a really smart, soft robot, and we don’t need ourselves in the loop.”
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