Optical Fiber Integrated Photoelectrochemical Sensing Patch: Toward Noninvasive Blood Glucose Detection

In recent years, noninvasive blood glucose detection has received increasing attention. Among them, sweat glucose detection is expected to become an alternative to blood glucose detection due to advantages such as its samples easily to obtain. This study was proposed and preliminarily verified a prototype of photoelectrochemical (PEC) sensing patch based on an optical fiber modified by Indium tin oxide (ITO)/ZnO/polydopamine (PDA)/glucose oxidase (GOD) and printed electrode, enabling close contact with human skin. In this innovative design, the optical fiber to serve both as a light transmission medium and a working electrode (WE), while the printed electrode functions as the counter electrode and reference electrode. The electrode materials were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), and X-ray photoelectron spectrometer (XPS), and the reaction kinetics of the optical fiber electrode studied through square wave voltammetry (SWV), electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis. A linear relationship was established between the photocurrent and the logarithm of glucose concentration in the concentration range from $10~\mu $ M to 1 mM, with a detection limit of $3.5~\mu $ M, and a response time of less than 1 s. In addition, the specificity and stability of the sensing patch were evaluated, and an attempt was made to detect real sweat glucose in situ. This work presents a novel prototype for the development of wearable sensors, with promising applications in biochemical analysis and health monitoring.