Spiderweb-inspired electronically conductive hygroscopic adhesive for chronic bioelectronic interface

Long-term physiological signal monitoring is critical for accurate diagnosis and effective management of chronic diseases. However, current electrode technologies face significant drawbacks: dry electrodes exhibit high electrochemical impedance and poor adhesion to skin, while wet electrodes suffer from short service lifetimes due to water loss. Inspired by the hygroscopic properties of spider webs, we developed an electronically conductive hygroscopic adhesive (termed as "hygrotrode") that continuously absorbs ambient moisture through a cross-linked, three-dimensional hygroscopic polymer network. This design maintains a low interface impedance and high adhesion energy for over a year, facilitated by absorbed intermediate water that electrochemically bridges the conducting polymer and skin tissue. The specific impedance of hygrotrode is 82.4 times lower compared with wet electrodes after 1 year. We further demonstrate hygrotrode's suitability for chronic biopotential monitoring and electromyography-based gesture recognition, highlighting its wide-ranging applicability in long-term wearable electronics and human-machine interfaces.