2023-06-02 16:45:13
Ee gentle touch, pain, heat, cold or wetness – wearers of prostheses would like nothing more than to be able to feel it all again. Many of those affected can already control their artificial limbs via special interfaces and, for example, grasp objects with a hand prosthesis. However, the artificial limbs have so far lacked the necessary sensitivity. An electronic skin with tactile abilities developed by scientists led by Zhenan Bao der Stanford Universityraises the hope among wearers of hand prostheses that they will be able to feel something again in the future.
The artificial skin essentially consists of elastic field effect transistors that convert mechanical pressure into electrical signals. These are passed on to an artificial synapse – a neuromorphic transistor – which can be attached to a patient’s forearm, for example, and is thus in contact with a receptor via a muscle. In this way, the original mechanical stimulus would be transmitted to a region of the brain that processes tactile sensations. The wearer of a hand prosthesis whose artificial fingers are covered with such an e-skin can feel something again via feedback. At least that’s the idea of Bao and her colleagues.
So far, the researchers have only tested their system on one rat. While a researcher held the E-skin between two fingers, the artificial synapse was attached to a spot on the animal’s hind leg. When the researcher squeezed the E-skin, certain muscles on the rat’s leg began to twitch. The harder the researchers squeezed the sensor, the more pronounced were the movements of the leg, as Bao and her colleagues report in the journal Science. The mechanical stimuli were actually passed on from the electronic skin to that part of the cerebral cortex that is responsible for haptic perception. Neurons in the neighboring motor cortex sent corresponding impulses to the rat muscle. The circle between stimulus, sensation and movement was thus closed, according to the researchers.
Robots with tactile abilities conceivable
According to Bao’s scientists, a major advantage is that the e-skin only requires an operating voltage of a few volts, which enables it to be used safely on humans. Existing e-skins would require much higher voltages of between 30 and 100 volts. In principle, heat and moisture could also be felt with the E-skin.
Because wearers of prostheses would be able to perceive something with their artificial limbs again thanks to the electronic skin, the quality of life of the people affected would improve significantly, writes Tsuyoshi Sekitani of Osaka University in an accompanying commentary. The Japanese materials researcher also sees a potential application in robotics: If robots were equipped with the electronic skin, they could be given tactile abilities. Machines would “feel” bumps and touches and process them in their electronic brains. This could prevent unwanted collisions between people and a robot arm in an automated workplace, for example.
Now the researchers would have to Stanford check how robust the skin is under real conditions and whether it can be used for practical applications. Also, Bao and her colleagues don’t know what the e-skin signals really feel like. This would require testing the technology on humans.
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