Laser-Induced Graphene-Assisted Patterning and Transfer of Silver Nanowires for Ultra-Conformal Breathable Epidermal Electrodes in Long-Term Electrophysiological Monitoring

Nanomaterial-based stretchable electronics composed of conductive nanomaterials in elastomer can seamlessly integrate with human skin to imperceptibly capture electrophysiological signals. Despite the use of transfer printing to form embedded structures, it remains challenging to facilely and stably integrate conductive nanomaterials with thin, low-modulus, adhesive elastomers. Here, a facile-yet-simple laser-induced graphene (LIG)-assisted patterning and transfer method is demonstrated to integrate patterned silver nanowires onto an ultra-low modulus silicone adhesive as ultra-conformal epidermal electrodes. The resulting thin epidermal electrodes of ≈50 µm exhibit a low sheet resistance (0.781 Ω sq⁻¹), tissue-like Young's modulus (0.53 MPa), strong self-adhesion, and excellent breathability. The breathable electrodes dynamically conformed to the skin with low contact impedance allow for long-term, high-fidelity monitoring of electrophysiological signals in complex environments (even during exercise and heavy sweating). Moreover, the LIG-assisted transfer can provide a robust interface to establish a stable connection between the soft electrodes and rigid hardware. The large-scale fabrication further provides an eight-channel electromyography system combined with a deep learning algorithm for gesture classification and recognition with remarkable accuracy (95.4%). The results from this study also provide design guidelines and fabrication methods of the next-generation epidermal electronics for long-term dynamic health monitoring, prosthetic control, and human-robot collaborations.