Channel‐Imprinted Organic Electrochemical Transistors Enabled Femtogram‐Level Pollutant Detection

ABSTRACT Organic electrochemical transistors enable highly sensitive and flexible sensors. However, it is challenging to achieve portability, cost‐effectiveness, and high sensitivity simultaneously, limiting its use in chemical screening. Here, we present a channel‐imprinted organic electrochemical transistor with exceptional sensitivity and selectivity based on a composite semiconducting channel with a sub‐10 nm imprinting layer. The device is manufactured based on commercially available screen‐printed electrodes and is ready to use in field applications. Simply by electrodepositing an imprinted layer on the channel in the presence of targets, it endowed the device with a unique binding‐induced charge carrier modulation mechanism. Targets bind to the imprinted layer, leading to the composite's conformational change and enhanced conductivity, resulting stronger output current at higher concentration. Through such, the PFOA imprinted sensor achieved an extremely low detection limit of 5.67 fg/L with a linear response range of 40 fg/L–4 ng/L, selectivity above 8.0, and a coefficient of variation lower than 6.3% from 20 devices. The femtogram‐level detection limits can be achieved both at transfer mode with scanning gate bias, and i‐t mode with 0 gate bias. The field‐deployable design highlights its practicality in environmental monitoring. Detection of various pollutants can be achieved simply by replacing templates.