Artificial Skin Could Give People with Prosthetics a Sense of Touch

Artificial skin created in a lab can "feel" similar to the way a fingertip senses pressure, and could one day let people feel sensation in their prosthetic limbs, researchers say.

The researchers were able to send the touching sensation as an electric pulse to the relevant "touch" brain cells in mice, the researchers noted in their new study.

The stretchy, flexible skin is made of a synthetic rubber that has been designed, to have  micron-scale pyramid like structures that make it especially sensitive to pressure, sort of like mini internal mattress springs. The scientists sprinkled the pressure-sensitive rubber with carbon nanotubes— microscopic cylinders of carbon that are highly conductive to electricity — so that, when the material was touched, a series of pulses is generated from the sensor.The series of pulses is then sent to brain cells in a way that resembles how touch receptors in human skin send sensations to the brain.

To test whether the skin could create electric pulses that brain cells could respond to, the scientists connected the synthetic skin to a circuit connected to a blue LED light. When the skin was touched, the sensor sent electric pulses to the LED which pulsed in response. The sensors translated that pressure pulse into an electric pulses. When the sensors in the skin sent the electrical pulse to the LED — akin to touch receptors in real-life skin sending touch-sensation signals to the brain — a blue light flashed. The higher the pressure, the faster the LED flashed.

Scientists added channelrhodopsin, a special protein that causes brain cells to react to blue light, to the mouse brain cells. The channelrhodopsin let the LED light act like receptor cells in the skin. When the light flashed it sent a signal to the brain cells that the artificial skin had been touched.