3D-printable alginate-MoS₂-AgNW hydrogel bioink for dual-mode wearable capacitive biosensors

The advancement of bioinks capable of enabling multifunctional, skin-conformal sensing platforms is essential for the next generation of wearable health monitoring systems. In this study, we present a 3D-printed, dual-mode biosensor fabricated using a composite hydrogel ink comprising sodium alginate, exfoliated molybdenum disulfide nanosheets (MoS₂NSs), silver nanowires (AgNWs), and Ca²⁺ crosslinkers. This bioink enables reliable extrusion-based printing on flexible substrates, forming wearable, conductive, and mechanically robust sensor architectures. The resulting soft sensor exhibits high-sensitivity capacitive touch sensing with fast response times and excellent mechanical repeatability under dynamic loading conditions. Furthermore, the device allows for real-time monitoring of sweat rate in response to constant humidity and perspiration levels. The synergistic integration of 2D MoS₂NSs and 1D AgNWs significantly improves electrical conductivity and mechanical durability, without compromising printability or hydration compatibility. The demonstrated dual-sensing functionality and scalable fabrication strategy underscore the potential of this platform for low-cost, customizable applications in wearable healthcare, fitness tracking, and human-machine interfaces.