Electronic tissue technologies for seamless biointerfaces

Bioelectronic interfaces establish a communication channel between a living system and an electrical machine. The first examples emerged in the 18th century when batteries were used to “galvanize” muscles and nerves. Today bioelectronic interfaces underpin key medical technologies such as the cardiac pacemaker and emerging ones such as neuroprostheses and brain-machine interfaces. Despite compelling applications in living systems, bioelectronic interfaces employ materials from microelectronics that are rigid, impermeable to water and bioinert. In contrast, electrical phenomena in soft tissues such as muscle and nerve are mediated by ions and molecules solvated in water. This disparity leads to missed opportunities for achieving seamless interfaces and communication that extends beyond electrical stimulation and recording. In this perspective, I discuss opportunities presented by hydrogel materials for building bioelectronic interfaces. This will require new types of hydrogels that support both ionic and electronic conductivity combined with key functions of the extracellular matrix.