A Water‐Gated Organic Thin‐Film Transistor for Glyphosate Detection: A Comparative Study with Fluorescence Sensing

Abstract

Abstract This work reports the design of a highly sensitive solid‐state sensor device based on a water‐gated organic thin‐film transistor (WG‐OTFT) for the selective detection of herbicide glyphosate (GlyP) in water. A competitive assay among carboxylate‐functionalized polythiophene, Cu 2+ , and GlyP was employed as a sensing mechanism. Molecular recognition phenomena and electrical double layer (EDL) (at the polymer/water interface) originated from the field‐effect worked cooperatively to amplify the sensitivity for GlyP. The limit of detection of WG‐OTFT (0.26 ppm) was lower than that of a fluorescence sensor chip (0.95 ppm) which is the conventional sensing method. In contrast to the previously reported insulated molecular wires to block interchain interactions, molecular aggregates under the field‐effect has shown to be effective for amplification of sensitivity through “intra”‐ and “inter”‐molecular wire effects. The opposite strategy in this study could pave the way for fully utilizing the sensing properties of polymer‐based solid‐state sensor devices.