14 DAY TRIAL // The new foldable integrated silicon circuits developed at the University of Illinois could turn the brittle electronic devices we use today into elastic silicon and plastic circuits only 1.5 micrometers thick, that can absorb the mechanical stress applied on them without suffering any damage. The inventor of the device, John Rogers says: "Making it thin makes it bendable, just as a piece of paper is bendable whereas a piece of wood is not."
The silicon circuits created on the plastic sheet are only one-crystal thick, thus reducing the mechanical limits imposed by material thickness, such as the case of silicon wafers. Because the electrical circuits are so thin, most of the mechanical stress applied on the chip is diverted towards the plastic material, rather than the silicon structure.
According to Rogers, the elastic chip is so thin that it could actually be folded around the edges of a coin, without it ever experiencing any damage.
How did he do it?
Rogers reveals that in order to make the chip flexible, silicon circuitry is first being applied on a rubber sheet while it is stretched to about 15 percent its original size. The two materials are then bonded together and the tension applied to the rubber sheet is released.
"It snaps back to its pre-stretched state and buckles with the attached circuit like an accorion bellows," Rogers adds.
Once the fabrication stage is over, the elastic circuit can then be stretched to 15 percent of its size without the silicon circuitry experiencing any damage. University of Wisconsin researcher Zhenqiang Ma, who was not involved in the study, says that although the idea is not new, nobody ever tried to create such circuits. "This will not completely transform the integrated circuited world, but it will fill an important gap, where regular semiconductors can not go."
Although elastic circuitry could have a potential large number of applications, amongst which creating wearable gadget clothing, Rogers believes that his invention could have a better use inside the human skull, and is already collaborating with Brian Litt in order to make this possibility a reality. He envisions such a foldable circuit covering parts of the human brain to detect signal patterns, and observe them to predict brain seizures.
Rogers also reveals that he is currently working on creating flexible circuits without the use of silicon, albeit even if he succeeds, the mere flexibility of such devices might just be not enough to wrap objects like the human brain. "You can't take a sheet of plastic and wrap a brain, you really need stretchability."