A team of University of Wisconsin—Madison engineers has created the world’s fastest stretchable, wearable integrated circuits. Stretchy electrical interconnects are already used in wearable electronics, but they work with direct current or low-frequency signals that are incompatible with microwave electronics. The new integrated circuits can operate at radio frequency levels up to 40 gigahertz, a range that supports the next generation of wireless communication known as 5G technology.
“We’ve found a way to integrate high-frequency active transistors into a useful circuit that can be wireless,” says Zhenqiang “Jack” Ma, who led the research. “This is a platform. This opens the door to lots of new capabilities.”
The stretchy integrated circuits are so speedy because of their unique structure, which was inspired by twisted-pair telephone cables. They are made of two intertwining power transmission lines in repeating S-curves. This shape allows the lines to stretch without affecting their performance. At the same time, it also helps shield the lines from outside interference and it eliminates current loss by confining the electromagnetic waves.
The device is only 25 micrometers (or .025 millimeters) thick, which is small enough to be used as a tattoo-like patch for medical applications. It could, for example, be used to remotely and wirelessly monitor patients’ vital signs with a small patch that could replace today’s cumbersome cables and wires.
In a paper that published in the journal Advanced Functional Materials on May 27, 2016, the authors wrote:
These concepts form the basic elements used in the design of stretchable microwave components, circuits, and subsystems performing important radio frequency functionalities, which can apply to many types of stretchable bioelectronics for radio transmitters and receivers.