Skin provides more than just a protective barrier for our inner bits—it’s also one of the nervous system’s most valuable tools for experiencing the outside world. People who have endured severe burns, amputations, or other injuries are therefore left without a way to experience touch sensitivity on certain parts of the body. With the right execution, technology could help fill that gap for those who wish to regain tactile sensation. A team of researchers at Stanford University has created an electronic skin that mimics the real thing, potentially offering a new sensory window for the body and future prosthetics.
The “e-skin” looks a bit like a super-thin sticker. In actuality, it’s far more complex. A single sheet of the transparent e-skin consists of a soft integrated circuit that runs on five volts of electricity (just a fraction of the team’s 30-volt starting point). The e-skin’s tri-layer structure is dielectric, meaning it transmits electricity without conduction, and it consists of three inner layers that allow the integrated circuit to use a lower voltage. Each layer contains organic nanostructures that can be individually engineered to pick up on different sensory inputs; while one might detect temperature, another helps the user experience pressure.
Credit: Jiancheng Lai and Weichen Wang/Bao Research Group/Stanford University
On their own, these layers make up a device that’s less than a micron thick. This is too thin to handle easily, so the team introduced a soft substrate that supports the circuit and improves its durability. The resulting product is as thin as a sheet of paper—or, more aptly, as thin as the human body’s outermost layer of skin.
In an experiment involving rats, the researchers stimulated the e-skin while using a computer to watch for nerve responses. Applying pressure or warm temperatures to the skin elicited leg twitches and nerve firings, proving that the technology could facilitate the sense of touch. Just as importantly, the e-skin could be folded and stretched repeatedly without tearing or impacting the inner circuit.
Stanford’s e-skin might someday return sensory abilities to people with tactile disadvantages. It could also be integrated into life-like prosthetics, which would increase the user’s mobility and allow them to feel using an artificial limb. But both of these cases are likely far off in the future. Because the e-skin is built from organic materials, it might not last long after being integrated into the human body. It’s also only capable of picking up on pressure and temperature fluctuations so far. More circuits with diverse sensory detection capabilities will hopefully make the technology more versatile.