In order to reach their full potential, soft robotic devices can't just consist of rigid electronic components encased in squishy rubber. A new material could help in that regard, as it's soft, self-healing and electrically conductive.
Developed by a team of scientists at Carnegie Mellon University, the substance consists of a gelatinous polyvinyl alcohol-sodium borate base, embedded in which are silver microflakes and gallium-based liquid metal droplets. It's also infused with ethylene glycol, to keep it from drying out.
Not only is the material fully capable of conducting a robust electrical current, but it can be stretched up to 400% of its relaxed length without breaking. Additionally, if a piece of the material is sliced in two, it can both mechanically and electrically heal itself back into one piece.
In a test of the gel, a strip of it was used to connect a battery to a motor along the outside of a soft-bodied robotic snail. When that strip was sliced all the way through (with the two severed ends still touching one another), the snail's speed dropped by over 50%. Once the ends had healed together, the speed increased up to 68% of the original velocity.
In another test, two strips of the gel were initially used to relay an electrical current to the motor of a toy car. The scientists proceeded to cut sections out of the middle of both strips, join the cut ends of the strips back together to resume powering the motor, and use the two extracted sections to power an LED on the car's roof.
Finally, small pieces of the material were used in place of traditional rigid electrodes to obtain electromyography (EMG) readings from different locations on a volunteer's body.
"Instead of being wired up with biomonitoring electrodes connecting you to biomeasurement hardware mounted on a cart, our gel can be used as a bioelectrode that directly interfaces with body-mounted electronics that can collect information and transmit it wirelessly," said the lead scientist, Prof. Carmel Majidi.
And the possibilities don't stop there …
"It would be interesting to see soft-bodied robots used for monitoring hard-to-reach places – whether that be a snail that could monitor water quality, or a slug that could crawl around our houses looking for mold," he added.
A paper on the research was recently published in the journal Nature Electronics. The functionality of the material is demonstrated in the video below.
Source: Carnegie Mellon University
