Conformal, Multi-Interface Flexible Film for Robust Electrophysiological Monitoring

Flexible conductive films often suffer from poor conformability, limited biocompatibility, and unstable electrical conductivity, which hinder their application in dynamic biointerfaces. To address these limitations, this work presents a simple and efficient strategy to fabricate an ultrathin, sandwich-structured multifunctional flexible conductive film (FCF) that achieves conformal integration with various biointerfaces and flexible devices. A stable interlayer integration with high conductivity is achieved by ultrasonically pretreating EGaIn (Ga75In25) with MOF particles in a binder-free manner. The film can clamp tightly into joint areas for real-time monitoring of joint movement. Furthermore, it may also form good quality electrical contact with the heart and brain, allowing high-quality electrocardiogram (ECG) and electroencephalogram (EEG) recording. The composite film showed excellent electromechanical stability as it can perform well through 2000 stretch cycles (0–10% strain) and 24 h water flow erosion. Tests for cytocompatibility have confirmed its excellent biocompatibility together with the remarkable stability of the EEG recording for over 2 weeks. The FCF successfully overcomes traditional compatibility challenges found in soft electronic devices attached to complex biological surfaces, enabling large-scale multisite long-term physiological monitoring.