An electrically conductive silver–polyacrylamide–alginate hydrogel composite for soft electronics

Hydrogels offer tissue-like compliance, stretchability, fracture toughness, ionic conductivity and compatibility with biological tissues. However, their electrical conductivity ( 350 S cm−1) and is capable of delivering direct current while maintaining soft compliance (Young’s modulus < 1 kPa) and deformability. Micrometre-sized silver flakes are suspended in a polyacrylamide–alginate hydrogel matrix and, after going through a partial dehydration process, the flakes form percolating networks that are electrically conductive and robust to mechanical deformations. To illustrate the capabilities of our silver–hydrogel composite, we use the material in a stingray-inspired swimmer and a neuromuscular electrical stimulation electrode. A hydrogel composite that consists of micrometre-sized silver flakes suspended in a polyacrylamide–alginate hydrogel matrix exhibits a high electrical conductivity of over 350 S cm−1 and a low Young’s modulus of less than 10 kPa.