Scientific discoveries have come from rigorous investigations of phenomena and a sudden flash of insight. They have also come from long-term studies and a fresh variation of an oft-repeated experiment. The path to scientific breakthrough can take many directions, as evidenced by a few examples of the discoveries made by researchers from the Beckman Institute.
Dahl-Young Khang wasn't trying to make scientific history. He wasn’t even trying to push the boundaries of silicon into territory scarcely imagined by researchers.
The young Rogers Research Group postdoc may have done both those things, however, by improvising a low-tech solution to a laboratory problem and by paying attention to what happened next.
Working in the Materials Research Laboratory, Khang, a postdoctoral research associate for Beckman Institute faculty member John Rogers, was repeating a process he had done many times before as part of Rogers’ wide-ranging explorations of the nexus point where electronics meet materials.
Swathed in the required cleanroom garb of thin plastic gown, cap, and boots, rubber gloves, and thick goggles, Khang gently pressed down on the little trapezoidal-shaped piece of clear, rubbery material just as he had done dozens of times before. The tiny (about an inch long) organic polymer piece of Polydimethylsiloxane (PDMS) wasn’t contacting well with the silicon substrate, however, thus preventing the experiment’s goal of transferring thin ribbons of silicon onto the piece of PDMS. So Khang decided to try using a glass vial from the lab to press down on the PDMS, much like a baker using a rolling pin.
When Khang peered at the results under a microscope the view wasn’t one of flat, straight ribbons of silicon that he was used to seeing, but a series of undulating patterns on the thin strips of silicon. Surprised and disappointed, Khang went over in his head what had happened. Two days before, he had left the silicon—etched into strips through a lab process that uses hydrofluoric acid— in his office desk for a couple of days. The exposure to room temperature left them difficult to work with—so Khang reached for that glass vial.
After seeing the results, Khang followed up on the aberration by repeating the new procedure, and by getting a better look at the wavy patterns on the silicon strips through an atomic force microscope. He then reported the news to Rogers, a member of Beckman’s 3-D Micro and Nanosystems group. Rogers said Khang was practicing good science.
“Our experience is that a lot of science is just being a careful observer of what’s happening in your experiments,” Rogers said. “This is a very good postdoc I have. Aless careful observer would have just glanced over it and said ‘oh what are these wavy things? I must not have done the printing right’ and gone back and done the printing and forgotten about it.”
Khang said his first reaction to seeing the wavy patterns was disappointment, but then his scientific curiosity took over.
“Right afterward, I thought about the possibilities,” he said. “What led to this weird shape instead of flat, beautiful images? So I started to think about what caused this kind of result.”