Aptamer Functionalized ZnO Thin-Film Transistor Based Multiplexed Detection of Pb and E. Coli in Water

In this work, we demonstrate the multiplexed detection platform to sense lead (Pb2+) and Escherichia coli in water using zinc oxide (ZnO) thin-film transistors (TFTs). Low-voltage ZnO TFTs fabricated by physical vapor deposition were functionalized with (3-Aminopropyl)triethoxysilane (APTES)–glutaraldehyde (GLU) molecules. TFTs with such functionalized ZnO surfaces showed good sensitivity and high specificity to the targets with a detection limit of 27 nM and $10^{{5}}$ colony forming unit per mL (cfu/mL) for Pb2+ and E. coli, respectively, with the TFT flat-band voltage ( ${V} _{\text {fb}}$ ) and, hence, the TFT transconductance, being dependent on the target concentration. The direct integration of the sensing with the TFT and associated integrated circuits promises high-density sensor arrays.