So he gave silicon a second look. He soon developed a technique for shearing it into sheets so vanishingly thin—100 nanometers, or one-thousandth as thin as a human hair—that it did something few dreamed possible: It flexed, twisted and, when threaded in a snaky pattern, even stretched. Then he went further. In a cover article in Science last year, he announced that if you made silicon skinnier still—35 nanometers—it would fully dissolve into biological fluids or water in a matter of days.
A conventional silicon wafer’s one-millimeter thickness, Rogers knew, had nothing to do with conductivity: The heft is there mainly so robots can move it through the various steps of fabrication without breaking.
“You have this gigantic industry based around wafer-based electronics, and for that reason, people traditionally look at silicon and say, ‘Well, it’s not flexible, we have to develop a different material for flexible circuits,’” he says. “But if you think about it more at the level of the mechanics, you quickly realize it’s not the silicon that’s the problem, it’s the wafer that’s the problem. And if you’re able to get rid of the underlying silicon materials not involved in the operation of the circuit, you’re left with a very thin sheet of silicon,” as floppy as loose-leaf paper.
At the end of one workday in July, Rogers slipped into a conference room beside his office and stepped out moments later in athletic shorts, white tube socks and sneakers. Before we left campus, to meet his wife and son for tennis at a public park, he gave me a tour of his office, whose bookcases were full of demos of his inventions, encased in plastic jewel boxes: The labels read “fly eye camera,” “proximity sensor on vinyl glove,” “stretchable solar cells,” “twisted LED.”
Rogers brushes aside the idea that his flexible and stretchable electronics represent any sort of quantum leap. “Our stuff is really just Newtonian mechanics,” he says. His silicon is to a factory-made wafer what a sheet of paper is to a two-by-four: the same salami, just sliced a lot slimmer.
“One of John’s strengths is he recognizes how to take a technology that already exists in a highly developed form and add something new to it so that it has new applications,” says George Whitesides, the renowned Harvard chemist, in whose lab Rogers worked as a postdoc. “He’s extraordinarily creative at this gap between science and engineering.”
Rogers’ transient circuits are sheathed in silk protein, which protects the electronics from liquid and can itself be formulated to dissolve in a few seconds or a few years. Inside the silk are circuit components whose materials—silicon, magnesium—break down into chemicals found in some vitamins and antacids. (In a speech to an engineering group last December, Rogers gulped down one of his circuits on a dare. “It tastes like chicken,” he joked with the audience.)
Years of clinical trials, followed by regulatory approvals, await any introduction of these devices into the human body, and precisely how to power and wirelessly connect with them is an area of active study. But the worlds of science, business and government have taken early and frequent notice. In 2009, the MacArthur Foundation, in awarding him a “genius” fellowship, called his work “the foundation for a revolution in manufacture of industrial, consumer and biocompatible electronics.” Two years later, he won the Lemelson-MIT Prize, a kind of Oscar for inventors. Each came with a check for $500,000.
To harvest his vast patent portfolio, Rogers has co-founded four startup companies. They have raised tens of millions of dollars in capital and are eyeing markets—biomedicine, solar power, sports, environmental monitoring and lighting—as eclectic as his creative impulses. Earlier this year, one company, MC10, in partnership with Reebok, launched its first product: Checklight, a skullcap with flexible silicon circuits, wearable alone or under football or hockey helmets, that alerts players to potentially concussive head impacts with a set of flashing LEDs.