Researchers from the Massachusetts Institute of Technology (MIT) have developed a wearable, skin-like sensor capable of measuring tiny facial movements and converting these into electrical signals. The team behind the device say it could be used to help people with amyotrophic lateral sclerosis (ALS) to communicate without the need for bulky, expensive equipment.

Consisting of four sensors embedded within a silicone film, the stretchy appliance fits snuggly onto the skin, following its movements while blending in with the surrounding skin tone. Best of all, the developers say their device could be made available for as little as $10.

Also known as Lou Gehrig’s disease, ALS is a degenerative condition that causes nerve cells to stop working, resulting in paralysis. Sufferers lose the ability to speak, which is why technologies are currently being developed to help patients communicate.

The most common devices use cameras to track minuscule facial movements or sensors that measure the electrical activity of nerve cells in the face, converting these into signals that can be used to select letters and words on an interface. Yet the cumbersome and impractical nature of these sizable pieces of equipment leaves a significant amount of room for improvement.

Documenting their work in the journal Nature Biomedical Engineering, the MIT researchers explain how their device consists of four piezoelectric sensors, which detect deformations in the skin and convert these into a measurable voltage.

The epidermal strain signatures from 16 different facial deformations were studied in various regions of the face, including the cheeks and temples, and fed into an algorithm. Once these signatures had been learned, the team tested their device on two ALS patients and found that it could distinguish between a smile, an open mouth, and pursed lips with 75 percent accuracy. In non-ALS patients, this success rate rose to 87 percent.

“We can create customizable messages based on the movements that you can do,” explained study author Canan Dagdeviren in a statement. “You can technically create thousands of messages that right now no other technology is available to do.”

For instance, certain facial movements could be used to transmit specific messages like “l love you” or “I’m hungry”.

Dagdeviren was also keen to stress the superior practicality of this new device over other systems currently on the market. “Not only are our devices malleable, soft, disposable, and light, they’re also visually invisible,” he said. “You can camouflage it and nobody would think that you have something on your skin.”