A medical robotic hand is just one potential application for the rubbery electronics reported by the researchers. (Image courtesy of the researchers)

Researchers at the University of Houston report that they have designed and produced a smart electronic skin and a medical robotic hand capable of assessing vital diagnostic data by using a newly invented rubbery semiconductor with high carrier mobility. According to the researchers, the rubbery material can be easily scaled for manufacturing, based upon assembly at the interface of air and water.

The interfacial assembly and the rubbery electronic devices described in their paper suggest a pathway toward soft, stretchy, rubbery electronics and integrated systems that mimic the mechanical softness of biological tissues, suitable for a variety of emerging applications.

The smart skin and medical robotic hand are just two potential applications.

Traditional semiconductors are brittle, so using them in otherwise stretchable electronics has required special mechanical accommodations. Previous stretchable semiconductors have had drawbacks of their own, including low carrier mobility — the speed at which charge carriers can move through a material — and complicated fabrication requirements. According to the researchers, adding minute amounts of metallic carbon nanotubes to the rubbery semiconductor of P3HT — polydimethylsiloxane composite — improves carrier mobility, which governs the performance of transistors.

Professor Cunjang Yu said the new scalable manufacturing method for these high performance stretchable semiconducting nanofilms and the development of fully rubbery transistors represent a significant step forward. The production is simple, he said. A commercially available semiconductor material is dissolved in a solution and dropped on water, where it spreads; the chemical solvent evaporates from the solution, resulting in improved semiconductor properties. This is a new way to create high-quality composite films, allowing for consistent production of fully rubbery semiconductors.

Electrical performance is retained even when the semiconductor is stretched by 50%, the researchers reported. Yu said the ability to stretch the rubbery electronics by 50% without degrading the performance is a notable advance. Human skin, he said, can be stretched only about 30% without tearing.