Hundred-Nanometer-Thick Stretchable Liquid Metal Films for Ultra-Conformal Bioelectrodes

Epidermal electrodes have demonstrated promising potential for high-fidelity electrophysiological monitoring owing to their superior conformability. However, achieving conductive films that simultaneously possess ultrathin architectures and high conductivity to enable super conformal skin integration and enhanced signal-to-noise ratios under dynamic conditions remains a formidable challenge. Here, a ≈200 nm-thick liquid metal (LM) conductive film and fabricate an epidermal bioelectrode is reported with a total thickness of merely 1.1 µm. The key innovation lies in a thermal-low temperature synergistic deposition strategy that combines in situ substrate precooling with thermal evaporation, which fundamentally differs from conventional LM film techniques (e.g., printing or sputtering) by enabling precise nanoscale control over film continuity and uniformity. This approach effectively suppresses the dewetting behavior of LM through low temperature stabilization of nucleation sites, thereby accomplishing layer-by-layer deposition of defect-free nano-conductive films (minimum thickness: 19 nm). The resulting film exhibits exceptional conductivity (3×10⁶ S·m^-1) without requiring mechanical activation. The fabricated epidermal electrode demonstrates outstanding skin conformability, ultralow interfacial impedance (8.5 kΩ at 1 kHz), and remarkable dynamic stability, enabling medical-grade electromyographic signal monitoring during motion. These advances highlight its significant potential for wearable bioelectronic applications.