A Photocurable Conductive Hydrogel for Force Sensing of Cross-Type Muscle Tissue

Accurate monitoring of the mechanical activity of muscle tissue is crucial for myocardial function assessment, human-machine interaction, and flexible electronics, yet it remains challenging to achieve mechanically compliant sensing with stable mechanical coupling to soft biological tissues. Here, we report a mechanically tunable and photocurable conductive hydrogel based on polyacrylamide/polyethylene glycol diacrylate/lithium phenyl-2,4,6-trimethylbenzoylphosphinate/silver nanowire (PAAm/PEGDA/LAP/AgNWs) composites. By rationally modulating the double-network structure and the AgNWs content, the material achieves a balanced integration of a Young's modulus (162 ± 9 kPa) matching that of muscle tissue, ultrahigh stretchability (>1200%), and stable electrical sensing, enabling effective force sensing under physiological deformation. Moreover, the photocurable nature of the hydrogel allows high-resolution fabrication via digital light processing (DLP) 3D printing, enabling in situ monolithic integration of sensing and encapsulation layers, which overcomes the manufacturability limitations of many previously reported conductive hydrogels. Two proof-of-concept devices were developed to demonstrate cross-type muscle sensing and cross-scale force detection, including long-term monitoring of contractile forces (15-30 μN) from in vitro cultured myocardial tissues using a microcantilever structure, and wearable facial muscle tension sensing in the range of 1-5 mN. This work demonstrates a scalable conductive hydrogel sensing platform that combines tissue-matched mechanics, advanced manufacturability, and broad biomechanical sensing capability, highlighting its potential for biomechanical research and human-machine interaction applications.