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

ABSTRACT 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.