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

Abstract

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.