A Neckband-Integrated Soft Microfluidic Biosensor for Sweat Glucose Monitoring

A neckband-integrated soft microfluidic biosensor was developed for real-time glucose monitoring in sweat. Flexible screen-printed electrodes were prepared and utilized for developing oxidase enzyme-based amperometric sensors. The electrochemical oxidation of glucose was catalyzed and mediated by bimetallic palladium and platinum-supported reduced graphene oxide and 1,10-phenanthroline-5,6-dione, respectively. Soft, microfluidic channels were prepared by developing clean-room free, 3D-printed master and integrated with the flexible sensors. The fluidic channel provides autonomous capillary flow of liquids through the sensor surface and facilitates real-time detection. The fluid flow analysis demonstrated homogeneous filling of the sensing chamber and the outlets within 8s. The developed biosensor showed good selectivity, sensitivity, and stability toward glucose in phosphate buffer solution as well as in human sweat samples. The sensor showed linear amperometric responses for glucose at 0.2 V ranging from 50 to 900 μM with a limit of detection of 37 μM and sensitivity of 30 μA cm –2 mM –1 . For real-life application, the pump-less microfluidic sensor was mounted on a 3D-printed neckband and coupled with a Bluetooth-enabled miniature potentiostat for wireless sweat glucose analysis. The real-time sweat glucose monitoring at the fasting stage and after spiking with glucose-rich meal showed good correlation with corresponding capillary blood glucose readings with a Pearson correlation coefficient of 0.87. Further, the sensor performances have been successfully validated by high-performance liquid chromatography. The presented wearable sensor offers facile noninvasive measurement of glucose levels from exercise-induced sweat samples for personalized diabetes monitoring.