During one of the half-hour slots into which he divides his 13-hour workday, we watched five undergraduates give precisely timed slide shows about their summer research projects. Rogers, his legs bouncing under the table as though racing toward some new revelation, pinged the students with questions, snapped a group photo and gave gift cards to the top presenters—all before the half-hour was up.
Whitesides told me that Rogers is unburdened by the “not invented here” syndrome that afflicts many scientists, who fear that collaborations somehow taint their originality. “John’s view is that if it’s a good idea, he’s perfectly happy to use it in a new way.”
“A lot of the most important advances in research are happening at the boundaries between traditional disciplines,” Rogers says. His Science article on transient electronics lists 21 co-authors, from six universities, three countries and one commercial consulting firm.
Students have inspired some of his best-known inventions. After hearing Rogers talk about soft lithography, one asked if the technology had ever stamped silicon, rather than just molecules of ink. “He didn’t have any idea how to do it, but he threw it out there as a question: the sort of question a first-year grad student would ask.”
The problem Rogers faced was, How do you turn hard silicon into a spongy ink pad? From a series of experiments, he found that if you sliced a silicon ingot into wafers at an unorthodox angle and then washed the wafer in a particular chemical solution, you could tenderize a thin surface layer that would come off on a stamp like ink. The pattern—a circuit element, for instance—could be lifted off and printed on another surface.
“No one had done that before,” says Christopher Bettinger, a materials scientist at Carnegie Mellon. Among the many technical enigmas Rogers untangled, he said, was “reversible stickiness.”
“If you lick your finger and put it in powdered sugar, you can pick up powdered sugar,” Bettinger said, by way of analogy. “But how do you then put the sugar down on something else?” Rogers did it with a shift in speed: To ink the stamp, touch and lift quickly; to inscribe onto a new surface, touch and lift slowly. The discovery allowed him to implant silicon “nanomembranes” just about anywhere: plastics and rubber, for his tattoo-like electronics, and silk, for the dissolvable ones. He found he could even stamp circuits directly onto skin.
Aleksandr Noy, a bioelectronics expert at Lawrence Livermore National Laboratory, told me that Rogers’ stature is a product of “papers, invited talks and record” but also of something intangible: “the cool factor.”
The money for Rogers’ transient electronics work comes mainly from the Defense Advanced Research Projects Agency (Darpa), a Department of Defense unit that funds some of the wildest ideas in science.