How to Give Fake Hands Real Feeling

The human hand has 17,000 touch sensors that help us pick things up and connect us to the physical world. A prosthetic hand or foot has no feeling at all.

Zhenan Bao hopes to change that by wrapping prosthetics with electronic skin that can sense pressure, heal when cut, and process sensory data. It’s a critical step toward prosthetics that one day could be wired to the nervous system to deliver a sense of touch. Even before that is possible, soft yet grippy electronic skin would let amputees and burn victims do more everyday tasks like picking up delicate objects—and possibly help alleviate phantom-limb pain.

Zhenan Bao

To mimic and in some ways surpass the capabilities of the skin on human hands, Bao is rethinking what an electronic material can be. Electronic skin should be not only sensitive to pressure but also lightweight, durable, stretchy, pliable, and self-healing, just like real skin. It should also be relatively inexpensive to manufacture in large sheets for wrapping around prosthetics. Traditional electronic materials are none of these things.

Bao (an MIT Technology Review Innovator Under 35 in 2003) has been working on electronic skin since 2010. She has had to create new chemical recipes for every electronic component, replacing rigid materials like silicon with flexible organic molecules, polymers, and nanomaterials.

A researcher makes a transistor on a stretchy rubber material that acts like a sticker. As the rubber is peeled from the glass, it picks up a layer of semiconducting carbon nanotubes that will form the active area of the electronic switch.

A slide is coated with an insulating material that will help turn the stretchy transistor off. Inside this machine, a small platform will spin the slide to make a thin, smooth film.

This stretchy transistor is made of carbon nanotubes, electronic polymers, and silver-nanoparticle ink. It could be used in circuits that process data from touch sensors.

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