Optical and Photoelectrochemical Optional-Mode Glucose Sensing Realized by Nanopatterned Au-TiO₂ Schottky Junction

Optical and electrochemical sensors have been widely employed to detect biochemical substances, but each one has its own strengths and weaknesses. In this study, an optical and photoelectrochemical (PEC) optional-mode sensor based on the nanopatterned metal-semiconductor-metal (MSM) structure is proposed for glucose detection. The MSM structure is designed and prepared by sequentially stacking a TiO2 film and the orderly Au nanodisks (NDs) on an Al film, and the Au and TiO2 contact forms the Schottky junction. In the optical term, the nanopatterned Au-TiO2 Schottky junction coupled with the Al film can produce an enhanced surface plasmon resonance (SPR) effect, which is used to construct a refractive-index sensor. In electrical terms, the Au-TiO2 Schottky junction can collect photogenerated carriers via the oxidation of glucose, resulting in an observable photocurrent changing with glucose concentration; that is, the prepared sensor can optionally work in optical and PEC modes. In the optical mode, the sensitivity for the design and experiment is 968.8 and 364.9 nmRIU-1, respectively. In the PEC mode, the sensitivity at relatively zero bias and under one-sun illumination is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1050~\mu $ </tex-math></inline-formula>AM-1cm-2 within the glucose concentration range of 0–10 mM. This work provides an alternate route to the achievement of multimode sensors for the large-concentration-range and low-detection-limit detection.