Nonenzymatic Glucose Detection Realized by Au and CuO Nanoparticle Co-Modified TiO2 Hierarchical Nanotubes Integrated With a Microfluidic Cell

Traditional enzyme-based blood glucose sensors demand stringent environmental conditions, while the current nonenzymatic blood glucose sensors exhibit low sensitivity and a limited detection range, hindering the accurate and swift analysis of minute liquid samples. In this study, the TiO2 hierarchical nanotubes (HNTs) were modified with Au and CuO nanoparticles (NPs) in sequence, and the as-prepared CuO-Au@TiO2 HNTs were constructed into a sensing photoelectrode and integrated into a self-designed microfluidic photoelectrochemical (PEC) cell. Accurate monitoring of glucose concentrations in artificial blood, sweat, and saliva was achieved by merely using a microliter analyte, along with satisfactory selectivity and repeatability. Notably, the fit sensitivity in the concentration range of 1–10 mM was over 29-fold higher than the traditional cell (i.e., nonmicrofluidic configuration) with the same sensing photoelectrode under one-sun illumination, and a detection limit was as low as $4.1~\mu $ M (Signal/Noise =3). The excellent sensing performances are ascribed to the synergistic effect of the substantial enhancement in optical absorption and carrier transfer and the dynamic flow of glucose confined in micro-channel. This study demonstrates an enzyme-free sensing photoelectrode integrated with a microfluidic cell for high-performance glucose detection, and presents an alternative avenue toward noninvasive and portable diabetes diagnosis.