Scientists are getting closer to producing prosthetic limbs that can sense touch. A team of researchers from Stanford University and Seoul National University have created an artificial nerve system that can not only sense differences in pressure but also read individual Braille letters. More amazingly still, they managed to hook the artificial nerves up to the leg of a cockroach and make the limb twitch.
“We take skin for granted but it’s a complex sensing, signaling and decision-making system,” says Stanford’s Zhenan Bao, co-author of the paper published in Science and whose lab has been developing the system, in a statement. “This artificial sensory nerve system is a step toward making skin-like sensory neural networks for all sorts of applications.”
The nerve circuit that the team developed is made up of three main components.
First, they took a sensor that can detect even the smallest of touches, and then connected this to a flexible electronic neuron. This meant that when something brushed up against the touch sensor, the change in voltage was converted by the neuron into electrical signals based on the pressure with which the sensor was touched.
These two components were finally linked to an artificial synaptic transistor. In the human body, synapses not only relay information but are also able to store this information and use it to make simple decisions.
“The synaptic transistor performs these functions in the artificial nerve circuit,” explains Tae-Woo Lee of Seoul National University, who first came up with the idea of the artificial synaptic transistor.
But the researchers did not end things there. They then managed to combine this technology with a biological system, using electrodes to connect the artificial synaptic transistor with the detached leg from a cockroach. When the team then touched the sensor, the electrical signals generated caused the insect's leg to twitch and contract.
The sensors were even able to do more than this: When a cylinder was rolled over the sensor, it was able to determine the direction in which the cylinder was moving. In another experiment, it could tell the difference between various Braille letters.
Advances in such technology may one day help improve the lives of people with artificial limbs, as well as help inform the technology of future robots.
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