Label‐Free Detection of a Neurotransmitter Using an Aptamer‐Functionalized Amorphous IGZO Transistor

ABSTRACT An indium–gallium–zinc (IGZO) thin‐film field‐effect transistor (FET) biosensor functionalized with a serotonin‐specific DNA aptamer is reported for label‐free serotonin detection in aqueous environments. The device operates under liquid‐gated conditions and functions as an ion‐sensitive FET, enabling pH monitoring across a broad physiological range (pH 4−10). Persistent challenges in aptamer‐based FET sensing—such as signal drift, interference from structurally similar molecules, and reliable integration of biomolecular layers with metal‐oxide semiconductors—are discussed in the context of IGZO‐based sensing platforms. The resulting devices exhibit reproducible electrical responses, with detectable serotonin response from 10 f m to 10 µ m and stable short‐term operation in buffered environments. This study demonstrates a straightforward approach for combining IGZO thin‐film transistors with aptamer‐based molecular recognition toward practical detection of small neurotransmitters.