A Wearable Paper-Based Patch Integrating Osmotic Sweat Extraction and Differential Sensing for Continuous L-Dopa Monitoring in Parkinson's Disease

Levodopa (L-Dopa) pharmacokinetic monitoring is crucial for optimizing therapy in Parkinson's disease (PD); however, existing sweat sensors are still limited by their reliance on active perspiration and poor specificity in complex biofluids. Here, we present a passive osmotic differential electrochemical (PODE) patch for continuous, non-invasive L-Dopa monitoring under resting conditions. The patch employs an ethylene glycol-loaded  polyacrylamide/polyvinyl alcohol (PAAm/PVA) hydrogel as a “chemical osmotic pump” to drive sweat transport without external power or physical exertion. For sensitive detection, a three-dimensional paper-based electrode is constructed via in situ growth of acrylamide-doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and gold nanoparticles (AuNPs). To eliminate interferences from uric acid (UA) and ascorbic acid (AA), a tyrosinase-enabled dual-channel differential sensing strategy is employed. The sensor exhibits a wide linear range and maintains high selectivity in complex artificial sweat. By seamlessly integrating passive sampling with interference-rejecting electrochemical detection, this flexible, low-cost patch offers a practical and user-friendly platform for personalized, at-home management of PD.