Engineering hydrogel-based conformal epidermal electrodes for human-machine interaction

Hydrogels, with their skin-like physicochemical properties, offer great potential as flexible electrodes for electrophysiological interfaces and high-quality biosignal acquisition in human-machine interaction systems. However, traditional hydrogel electrodes often face issues such as mechanical mismatch with skin, low electrical conductivity, and poor adhesion, which hinder stable biosignal acquisition with high signal-to-noise ratio. To address these challenges, optimizing conductivity, compliance, and adhesion is crucial. This perspective reviews recent advancements in hydrogel electrode optimization, materials design, interface engineering, human-machine interaction applications, and future directions for hydrogel-based biointerfaces.