Pt-poly(L-lactic acid) microelectrode-based microsensor for in situ glucose detection in sweat

A miniaturized biosensor was developed for in situ noninvasive detection of glucose in sweat. The biosensor was composed of a pair of interdigital Pt-poly(L-lactic acid) (Pt-PLA) microelectrode arrays operating as the working and auxiliary electrode. The size of the sensor was 3.56 × 0.72 mm, while the width of the interdigital microelectrodes was 2.4 μm. The microelectrodes with densely packed coral-like Pt-PLA nanoparticles were fabricated using a multi-potential step deposition process. We investigated the influence of the Pt-PLA electrodeposition time on the morphology and electrochemical performance of the microelectrode. The optimized biosensor exhibited high electrocatalytic activity because of the synergistic effects between the Pt nanoparticles and PLA polymer matrix, including the electrooxidation of Pt on glucose, the adsorption of glucose by the PLA polymer, and the acceleration of the glucose dehydrogenation step. For glucose detection in sweat and tears, the linear concentration ranges were observed to be 0.001–33.76 μM and 33.76–1000 μM, with a low detection limit of 0.19 nM. The miniaturized biosensor exhibited high sensitivity and signal stability, and could be suitable for use in the long-term monitoring of sweat glucose levels in patients, athletes, and other subjects in various difficult environments.