A Touch of Silver

Carnegie Mellon University - In the field of robotics, metals offer advantages like strength, durability and electrical conductivity. But, they are heavy and rigid - properties that are undesirable in soft and flexible systems for wearable computing and human-machine interfaces. Hydrogels, on the other hand, are lightweight, stretchable and biocompatible, making them excellent materials for contact lenses and tissue engineering scaffolding. They are, however, poor at conducting electricity, which is needed for digital circuits and bioelectronics applications. Researchers in Carnegie Mellon University's Soft Machines Lab have developed a unique silver-hydrogel composite that has high electrical conductivity and is capable of delivering direct current while maintaining soft compliance and deformability. The team suspended micrometer-sized silver flakes in a polyacrylamide-alginate hydrogel matrix. After going through a partial dehydration process, the flakes formed percolating networks that were electrically conductive and robust to mechanical deformations.