Highly Sensitive and Wearable In₂O₃ Nanoribbon Transistor Biosensors with Integrated On-Chip Gate for Glucose Monitoring in Body Fluids

TLDR

Nanoribbon- and nanowire-based FET biosensors have attracted much interest, but bulky Ag/AgCl or metal wire gates have hindered their wearable application. The study demonstrates highly sensitive, conformal In₂O₃ nanoribbon FET biosensors with an integrated on‑chip gold side gate, laminated onto surfaces such as artificial arms and watches, to enable glucose detection in body fluids such as sweat and saliva. The devices were fabricated via shadow‑mask lithography, integrated with an on‑chip gold side gate, and functionalized with glucose oxidase, chitosan, and single‑walled carbon nanotubes for sensing. The transistors exhibit ~22 cm² V⁻¹ s⁻¹ mobility in 0.1× PBS, a 10⁵ on‑off ratio, robust mechanics, and glucose sensors detect over five orders of magnitude down to 10 nM, indicating strong potential for wearable healthcare electronics.

Abstract

Nanoribbon- and nanowire-based field-effect transistor (FET) biosensors have stimulated a lot of interest. However, most FET biosensors were achieved by using bulky Ag/AgCl electrodes or metal wire gates, which have prevented the biosensors from becoming truly wearable. Here, we demonstrate highly sensitive and conformal In2O3 nanoribbon FET biosensors with a fully integrated on-chip gold side gate, which have been laminated onto various surfaces, such as artificial arms and watches, and have enabled glucose detection in various body fluids, such as sweat and saliva. The shadow-mask-fabricated devices show good electrical performance with gate voltage applied using a gold side gate electrode and through an aqueous electrolyte. The resulting transistors show mobilities of ∼22 cm2 V-1 s-1 in 0.1× phosphate-buffered saline, a high on-off ratio (105), and good mechanical robustness. With the electrodes functionalized with glucose oxidase, chitosan, and single-walled carbon nanotubes, the glucose sensors show a very wide detection range spanning at least 5 orders of magnitude and a detection limit down to 10 nM. Therefore, our high-performance In2O3 nanoribbon sensing platform has great potential to work as indispensable components for wearable healthcare electronics.