High-performance inkjet-printed organic electrochemical transistors for rapid NT-proBNP detection and biopotential amplification.

Organic electrochemical transistors (OECTs) are promising platforms for bioelectronic sensing due to their intrinsic signal amplification and compatibility with biological media. However, achieving high transconductance and fast temporal response using scalable printing techniques remains challenging. Here, we report high-performance inkjet-printed PEDOT:PSS OECTs enabled by systematic geometric optimization and plasma-assisted surface engineering. By controlling channel width, thickness, and length, and by improving printing resolution through wettability tuning, short-channel devices with lengths down to 9.5 μm were achieved. The optimized architecture exhibits transconductance values up to 84 mS and response times as low as 0.31 ms, approaching the performance of photolithographically fabricated devices while retaining the scalability of additive manufacturing. Leveraging the high intrinsic gain of the optimized devices, we demonstrate label-free detection of the heart failure biomarker NT-proBNP in both phosphate-buffered saline and human plasma across clinically relevant concentrations (10-500 pg mL-1). The platform demonstrates detectable responses down to 45 pg mL-1 in plasma, with stable operation in complex biological media and the ability to distinguish between clinically relevant NT-proBNP concentration ranges. In addition, the rapid device dynamics enable amplification of low-amplitude biopotential signals, demonstrated through in vivo seizure monitoring in a rat model. These results establish inkjet-printed OECTs as scalable, high-performance transducers capable of bridging printed bioelectronics with clinically relevant biosensing and electrophysiological monitoring applications.