A flexible biosensor for efficiently glucose monitoring in sweat based on copper nanoparticles modified PHEMA hydrogel

Wearable electrochemical sensors for glucose analysis hold significant potential for non-invasive monitoring of sweat biomarkers. However, the complex and expensive preparation process has limited the application of these sensors. In this study, we proposed an electrochemical glucose biosensor based on poly (2-hydroxyethyl methacrylate) (PHEMA) hydrogel initiated via iron ion and phenol hydroxyl groups. Copper nanoparticles are then incorporated into the hydrogel, enhancing the conductivity and electrocatalytic performance of the hydrogel electrode. The composite hydrogel, characterized by its rich metal coordination and hydrogen bonds, demonstrated remarkable cyclic adhesion properties, stretchability, and self-healing capability. Subsequently, this hydrogel is modified onto a screen-printed electrode (SPE) to create an in vitro skin patch for glucose detection in human sweat. The biosensor exhibits a wide linear range for glucose concentration of 0–0.2 mM and 0.2–4 mM, with low detection limit of 9.99 μM. The sensor exhibits good stability, selectivity and flexibility, and demonstrates a strong correlation with glucose measurements obtained from real sweat using a glucose assay kit. This sweat sensor holds great development potential, providing broad prospects for future non-invasive detection applications.