Ultra-flexible stretchable liquid metal circuits with antimicrobial properties through selective laser activation for health monitoring

Liquid metal (LM) was generally used to construct flexible wearable electronics to solve the stretchability-conductivity dilemma of traditional electronic devices. Herein, ultra-flexible and stretchable LM circuits with a unique layered structure (LM-Ag-Cu) are prepared by laser-induced selective metallization combined with the highly selective reaction wetting. The Ag-Cu layer is first prepared as templates using the laser-induced selective metallization technology on transparent flexible polymer films, and the LM circuit is obtained by brushing LM onto the Ag-Cu template. The prepared LM circuit demonstrates excellent conductivity and good electrical heating properties even under significant bending and stretching. Moreover, it also exhibits excellent antimicrobial resistance (>99 % antimicrobial activity against E. coli and S. aureus). When designing wearable bioelectrodes, the electrodes based on this LM circuit show accurate and stable real-time monitoring performance of biomechanical (motion detection) and bioelectrical signals (electrocardiography and electromyography signals). Because laser-induced selective metallization technology has characteristics of high-precision preparation of metal circuits, the obtained Ag-Cu layer is accurate and can be reactively infiltrated with LM, so that this new LM-Ag-Cu circuit is born with a layered structure. The LM circuit prepared through our strategy provides a practical and innovative approach to fabricating intelligent skin bioelectrodes.