A skin-affinitive organic electrochemical transistor based on all-hydrogel design for wearable biocomputing

Skin-integrated transistors have been explored for wearable sensing, computing and programmable synthetic bioelectronics. However, their high modulus, low sweat permeability, and limited scalability result in multidimensional mismatches with the real skin. Here, we introduce skin-affinitive organic electrochemical transistors (SA-OECTs) based on all-hydrogel, designed to simultaneously overcome these limitations. Our all-hydrogel SA-OECTs incorporates a semiconducting hydrogel channel and thus capable of conducting active sensing and computing functions. This unified all-hydrogel strategy yields the SA-OECTs with skin range softness (10-500 kPa), thickness (500 nm-500 μm), biocompatibility, breathability - a combination of properties unattainable with conventional transistors - while achieving tunable transistor characteristics via ion-electron conversion, achieving an on/off ratio exceeding 10 4 . Additionally, these all-hydrogel SA-OECTs exhibit a substantial enhancement in operational speed over conventional poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) based OECTs of equivalent dimensions. Leveraging these attributes, we constructed a SA biocomputing platform using an all-hydrogel SA-OECTs array, paving the way for biohybrid AI that bridges artificial and biological intelligence.