High Stability of Diketopyrrolopyrrole Polymer Transistors Under Aqueous Condition Toward Biosensing Platform

Diketopyrrolopyrrole (DPP)–based conjugated polymers show strong promise for electronic applications, including bioelectronic gas sensors, yet their use in aqueous environments remains largely unexplored, especially for minimally invasive point‐of‐care testing (POCT) biosensors. We present the first systematic study of DPP‐based organic field‐effect transistors (OFETs) that deliver highly stable signal responses under both ambient and aqueous conditions. A scalable lab‐on‐a‐chip fabrication strategy is demonstrated, highlighting the critical roles of polymer deposition, dielectric selection, and device engineering in achieving uniform and reproducible electronic performance. The resulting OFETs exhibit excellent operational stability in water and phosphate‐buffered saline (PBS), supporting their suitability for sensing biological fluids. Devices display high output current, low transfer hysteresis, and strong batch‐to‐batch consistency, and are fabricated entirely under ambient conditions without oxygen or humidity control, underscoring compatibility with large‐scale manufacturing. OFET operation is sustained with minimal signal drift for up to 1 h in water and PBS. Comprehensive characterization of water‐immersed DPP films using PESA, UV–vis spectroscopy, XRD, and ToF‐SIMS confirms material robustness. A pilot real‐time dopamine sensing study achieves a detection limit of 1 p m , demonstrating feasibility for biosensing. Overall, DPP‐based organic semiconductors represent strong candidates for robust aqueous OFET‐based POCT technologies.