Facile Fabrication of Low-Impedance, Highly Conformal Epidermal Electrodes Based on Laser-Induced Graphene–Silver Nanocomposites

Long-term and high-fidelity electrophysiological (EP) signal monitoring with conformal epidermal electrodes with low contact impedance and robustness against motion artifacts is of great significance for health monitoring and human–machine interfaces. However, the low-cost yet scalable fabrication of large-area electrodes and arrays with these desired properties remains challenging. Here, a facile strategy is reported to fabricate large-area, highly conformal, and low-impedance epidermal electrodes based on highly porous and conductive laser-induced graphene (LIG) nanocomposites. The patterned superhydrophilic LIG allows the self-selective wetting of silver ionic solutions into the porous structure, followed by reduction to form LIG–Ag nanocomposites with significantly reduced sheet resistance (from 50 to 0.06 Ω/sq) and also the skin contact impedance. Subsequent transfer of the nanocomposites onto an ultrathin (13 µm) styrene-ethylene-butylene-styrene (SEBS) substrate results in durable, highly conformal, and low-impedance epidermal electrodes even after storage for over 8 months. The resulting electrodes demonstrate superior signal-to-noise ratio (SNR) and resistance against motion artifacts for EP signal monitoring. The twelve-lead ECG monitoring and biopotential-based control of a robotic hand demonstrate the practical utility of these electrodes for clinical health monitoring and human–machine interactions.