YOUR SKIN IS an interface between your brain and the world. Okay, so that sort of sounds like a pickup line a materials scientist would use. But human skin is amazing: It’s exquisitely sensitive, quick on the uptake, and constantly giving you useful information about your surroundings. In a deep way, the ability to physically feel something helps people understand reality.
But electronic gadgets don’t feel any of this. At least, not yet. Scientists have spent the past decade trying to get tech to feel the same way humans do. Their first attempts could really only sense one thing at a time—temperature, say, or pressure. Researchers have tried to jerry-rig these systems together, but the results have been clunky. Now, researchers in Korea have developed their own compact electronic skin that multitasks like a person’s, sensing pressure, temperature, and sound (which is just air pressure, really) simultaneously.
In the study, published today in Science Advances, the scientists took design cues from fingertips, home to some of the most sensitive skin on the human body. Fingerprint ridges help amplify vibrations, making your sense of touch extremely fine-grained, so you can tell crinkly from grainy from velvety. Plus, the layers of dermis and epidermis underneath interlock with each other, which provides more points of contact. The artificial Korean skin is ridged, too, and likewise sandwiches two layers of bumpy film. So it’s sensitive enough to detect a strand of hair, and can discern between the scruffiness of a beard and lighter cheek stubble. (Yeah, they tried it.)
The key to getting the skin to multitask was the material, a combination of polymer and graphene oxide. When the temperature changes, the material generates electricity; when an object rests on the skin, resistivity changes as the bumps in the skin smush together. If a drop of water falls on the e-skin, scientists can tell how warm the water was, and from how high up it dropped.
It’s still just a proof-of-concept, but ideas for how to use skins like this one come pretty easily—think the Bionic Man, or Luke Skywalker’s prosthetic hand. But only recently has microfabrication tech caught up to humanity’s cyborg dreams. Now, every few months or so, a lab comes out with a new, different design: A bunch of sensors stuck to a glove! Circuitry printed on weird sticky paper! “We’re at a very nascent stage,” says Benjamin Tee, an e-skin researcher at the Institute of Materials Research and Engineering in Singapore. “It’s basically a Wild West for electronic skin right now.” Scientists are still throwing ideas out to see what sticks. And here, “sticking” means the tech’s ability to be cheaply mass-produced with decent specs.
In the short term, electronic skin probably won’t be anything’s actual skin. It’s promising for medicine, saysHeon-Sang Lee, a chemical engineer at Dong-A University and an author of the paper. The skin is sensitive enough to detect sound waves, which would make it useful in hearing aids. And his team has strapped their bendy, Scotch tape-thin skin around wrists to measure pulse. “You get a much better signal from skin-like materials than you do from boxy and rigid wearables,” says John Rogers, a materials scientist at the University of Illinois. Rogers’ lab is working on temporary tattoo-like electronics to collect health data. Further in the future, e-skins could make for more sensitive surgical robots, or maybe wrap around exoskeletons to help the elderly get around.
Beyond medicine, electronic skin is basically just a smart surface, so theoretically designers could slap it wherever humans interact with technology. Tee points to Apple’s recent investments in things like Force Touch and 3D Touch. “We’re definitely moving to seamless integration with the digital world,” he says. “The question is, how do we integrate with the digital world, which is essentially 1s and 0s, into something we can feel and interact with?” We’re all sensitive people—maybe our tech should be sensitive, too.