There’s no shortage of potential applications for artificial skin, including rehabilitation, exoskeletal surfaces, and monitoring chronic diseases. There are also plenty of challenges. Ideally, artificial skin needs to be lightweight, flexible and stretchable, durable, and soft to the touch. To work with biosensors and various human-machine interfaces, artificial skin also must conduct electricity. We’ve written about multiple developments in artificial skin. Researchers at EPFL developed artificial skin with touch sensing and haptic feedback. Caltech scientists developed artificial skin with temperature sensitivity. Researchers at Ulsan National Institute of Science and Technology (UNIST) in Korea created artificial skin that mimics the structure of a human fingertip and can also sense touch.

As published in Nature this month, researchers with the Carnegie Mellon University Soft Machines Lab have come up with a new silver-hydrogel composite that combines high electrical conductivity with soft and lightweight stretchability. Hydrogels ordinarily are biocompatible, stretchable, and lightweight, but lack conductivity. Carnegie Mellon engineers suspended micrometer-sized silver flakes in a hydrogel. Following partial dehydration, the silver flakes formed electrically conductive networks sufficiently strong to withstand deformation. The engineers experimented with dehydration and hydration to find a balance at which the sliver flakes can form reversible electrical connections by sticking together or breaking apart. The key to the Carnegie Mellon team’s success was in developing stretchable, conductive elastomers (highly elastic polymers) with the liquid metal.

Carmel Majidi, Carnegie Mellon professor of mechanical engineering suggested that applications for the composite could include signal processing stickers placed on the brain, wearable energy generators to power electronics, and stretchable displays. Created with methods similar to screen printing, the composite could be used in quantity to serve as a second layer of nervous tissue, Majidi said. Such applications could help treat muscular disorders and motor disabilities.