The Body Electric
Ever since humans invented computer chips, we have dreamed of plugging them into us, or plugging us into them. And why not? A living body is inherently electrical: once every second or so, a dime-size bundle of cells in the upper chamber of the human heart produces an electrical pulse that keeps the organ beating, until the pulse ceases and we die. Cells shuttle ions in and out, communicating in a language tantalizingly similar to the positive and negative charges of electrical circuits. Eyes, ears, nose, tongue, skin—these are merely interfaces, ways for a body to chemically convert the uncharged outside world into current that, as it leaps through the brain, creates our thoughts and feelings. In millivolts, we rue our limitations. If we could synch our synapses with manmade electronics, the thinking goes, we might ditch our bodies and become cyborgs, living forever as brains in jars, perhaps, or uploading our essential humanness to the Cloud.
The problem is physical: the body is soft, supple, and curved, but modern electronics, built on silicon computer chips, are rigid and flat, likely to shatter if dropped on a sidewalk. John Rogers, a shy-eyed materials scientist at the University of Illinois at Urbana-Champaign, likes to point out that, in 3.5 billion years, evolution has solved countless challenging problems without creating something that looks like a silicon chip. “You think about the natural world, there’s a lot of rough and tumble,” he told me. “You have environments that are a lot less well-controlled than an iPhone case.” Researchers traditionally considered marrying electronics to biology using circuits made not from inorganic silicon but from pliable organic materials—the carbon-based building blocks of life. But current flows through these materials too slowly to power computers and gadgets. Rogers had another idea. In 2011, he and his colleagues announced the invention of a device that had hitherto seemed impossible: an integrated silicon circuit with the mechanical properties of skin.
In the journal Science, Rogers revealed what looked like a gold bar code—the circuit—set in a transparent layer of dried glue. Photographs showed it stuck to a postdoc’s forearm, so that its wires were visible, or hidden under a temporary tattoo that featured a pirate in a Fighting Illini hat. The circuit stretched and wrinkled when spread and pinched. It was waterproof and could harvest power from radio waves, which are emitted by cell phones, to measure skin temperature, pressure from swelling, hydration level, and electrical signals from the brain and heart. To otherwise gather this basic medical information in real time requires a person to be tethered to machines, limiting the ability to study the health or physiological performance of a soldier, say, or a ballerina, or an insomniac. A wireless medical patch would render obsolete much of the clunky diagnostic equipment in hospitals. . . .