Self-powered implant could restore sense of touch to injured fingers
When someone injures a nerve in a body part such as a finger, it's not uncommon for that part to end up with a permanently decreased sense of touch. A self-powered implantable sensor, however, could one day restore sensitivity to such injured areas.
Created by a team at Israel's Tel Aviv University, the experimental device is intended to be surgically implanted under the skin in a compromised body part such as the fingertip, in which tactile sensation is lacking. That said, it could also be used in other regions.
It incorporates what's known as a triboelectric nanogenerator, or TENG for short. Putting it very simply, TENGs generate an electrical charge via the rubbing together of two different dielectric materials – the static charge created by shuffling across a carpet in your sock feet is an example.
The TENG in the sensor is made up of two square plates placed one above the other, with a small gap between them. Each plate is made of a different flexible material, measuring less than half a centimeter on each side.
When the fingertip comes into contact with a surface, pressure is applied to the TENG. This causes the two plates to come into contact with one another, generating an electrical charge. The current is carried along an insulated wire to an electrode cuff that's wrapped around the end of an adjacent undamaged nerve.
That nerve in turn relays the electrical signal to the central nervous system, resulting in the brain registering a sensation of touch in the fingertip. The greater the amount of pressure that's applied to the TENG, the higher the electrical charge that's released, and thus the more intense the sensation.
In lab tests conducted on rats, the sensor was reportedly able to restore tactile sensation to hind paws in which a nerve had previously been cut, allowing the animals to once again walk normally.
"Next, we want to test the implant on larger models, and at a later stage implant our sensors in the fingers of people who have lost the ability to sense touch," says the lead scientist, Dr. Ben M. Maoz. "Restoring this ability can significantly improve people's functioning and quality of life, and more importantly, protect them from danger. People lacking tactile sensation cannot feel if their finger is being crushed, burned or frozen."
The research is described in a paper that was recently published in the journal ACS Nano.