Ultra-Low Power Schottky Barrier TFT-Based Neurotransmitter Detection and Regenerative Studies

Abstract

There is limited work on understanding Schottky barrier (SB) field-effect transistor (FET) behavior, and subsequent evolution of sensitivity metrics under wet detection conditions for neurotransmitter sensing applications. In this work, we report low-power deep subthreshold (DST) characteristics of SB InGaZnO₄ (IGZO) thin film transistors (TFTs) and implement this regime for sensitive and selective <i>ex vivo</i> detection of Dopamine against Adenosine Triphosphate (ATP). Device regeneration was performed under liquid solution environment over 34 days and sensor response was observed to drift less than two orders of magnitude. Nevertheless, the quantified trends due to buffer solution baseline versus target conjugation were virtually preserved across the TFTs. Widely improved detection metrics were extracted from the detection tests, namely the limit of detection (LoD) in the 100fM-100pM range, a binding affinity (<inline-formula> <tex-math notation="LaTeX">$k_{D}$ </tex-math></inline-formula>) between <inline-formula> <tex-math notation="LaTeX">$2.03\times 10^{-11}$ </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">$3.02\times 10^{-9}\text{M}$ </tex-math></inline-formula> limits, and high sensitivity around 31-42mV/decade of target concentration. Although a steady drift with clear, repeatable differences between the device state at the start and end of the 34-day period were obtained, these devices were functional even after the regeneration test period. Such results can be used to estimate the regenerative lifetime of TFT biosensors under aptamer-immobilized solution environment detection conditions.