Washington, Nov 20 : Scientists have developed electronics that not only can be bended or stretched, but can also be twisted, which could pave the way for new flexible sensors, transmitters, new photovoltaic and microfluidic devices, and other applications for medical and athletic use.
Improving upon their so-called "pop-up" technology, the scientists have created circuits that can be subjected to any complex deformation, including twisting.
The research team included Yonggang Huang, Joseph Cummings Professor of Civil and Environmental Engineering and Mechanical Engineering at Northwestern University's McCormick School of Engineering and Applied Science, and John Rogers, the Flory-Founder Chair Professor of Materials Science and Engineering at the University of Illinois at Urbana-Champaign,
Such electronics could be used in places where flat, unbending electronics would fail, like on the human body.
Historically, electronic components have been flat and unbendable because silicon, the principal component of all electronics, is brittle and inflexible. Any significant bending or stretching renders an electronic device useless.
The new method, however, has been developed in order to fabricate stretchable electronics that increases the stretching range (as much as 140 percent) and allows the user to subject circuits to extreme twisting.
Earlier, Huang and Rogers developed a one-dimensional, stretchable form of single-crystal silicon that could be stretched in one direction without altering its electrical properties. Then they made stretchable integrated circuits.
Next, the researchers developed a new kind of technology that allowed circuits to be placed on a curved surface. The technology used an array of circuit elements approximately 100 Micrometers Square connected by metal "pop-up bridges."
The circuit elements were so small that when placed on a curved surface, they didn't bend -- similar to how buildings don't bend on the curved Earth.
The system worked only because metal wires connected the elements, and they popped on bending and stretching.
In the new study, the researchers used their pop-up bridges and made them into an "S" shape, which, in addition to bending and stretching, have enough give that they can be twisted as well.
"For a lot of applications related to the human body -- like placing a sensor on the body -- an electronic device needs not only to bend and stretch but also to twist. So we improved our pop-up technology to accommodate this. Now it can accommodate any deformation," said Huang.
Now, the researchers are focusing their research on another important application of this technology-solar panels.
Recently they described a new process of creating very thin silicon solar cells that can be combined in flexible and transparent arrays.
The research is published online by the Proceedings of the National Academy of Sciences (PNAS).