Stretchy Integrated Electronics Use a Sandwiched Semiconductor

There’s a barrier preventing truly elastic electronic systems needed for advanced human-machine interfaces, artificial skin, smart health care, and more. A Penn State-led research team found a way to stretch around it.

Fully elastic electronic systems require flexibility and stretchability in every component. Although researchers have achieved this in most components, one type of semiconductor is notoriously brittle.

N-type semiconductors conduct electricity through negative electrons carrying the charge, and in combination with p-type semiconductors, they act as a switch, with current flowing in one direction. Often rigid, they require specific strategies to make them more mechanically stretchy to achieve completely stretchable transistors and circuits with n-type semiconductors.

The researchers sandwiched the n-type semiconductor between two rubbery materials known as elastomers–polymers that stretch and snap back to their original shape. The stack architecture improved mechanical stretchability and suppressed the formation and propagation of microcracks in the brittle n-type semiconductor.

The elastic transistors retained high device performance even when stretched 50% in either direction. The devices also exhibited long-term stable operation for over 100 days in an ambient environment. Given that n-type semiconductors can lose efficiency with exposure to oxygen and moisture, when sandwiched between elastomers, the semiconductor is effectively encapsulated against the elements.

The work is published in Nature Electronics.