Extended‐Gate‐Type Organic Field‐Effect Transistors for Label‐Free Immunosensing

Abstract

Organic field‐effect transistors (OFETs) are electronic devices that exhibit switching behavior upon application of a gate voltage, and their device characteristics make them attractive platforms for bio/chemical sensing in analytical chemistry. However, the limited operational stability of many organic semiconductor layers in aqueous environments poses challenges for sensing applications, including those involving body fluids. To address this bottleneck, this Perspective focuses on the extended‐gate architecture, which physically separates the aqueous sensing interface from the organic semiconductor and can thereby improve operational stability. The extended‐gate surface can be chemically functionalized with recognition materials, such as antibodies, to introduce molecular recognition toward target analytes. The reported devices have demonstrated label‐free electrical responses to target biomarkers under their respective experimental conditions. Herein, representative extended‐gate architectures, including separated, semi‐integrated, and pseudo‐reference‐integrated configurations, are introduced. Representative surface‐engineering strategies for label‐free immunosensing are also described. Finally, the remaining challenges for translation to biomarker analysis are discussed.