Development of a wearable microfluidic amperometric sensor based on spatial three-electrode system for sweat glucose analysis

Most amperometric glucose sensors utilize nanomaterials to increase the surface area of the working electrode for sensitivity enhancement. However, this approach not only increases the cost and complicates the fabrication process, but also results in functional surfaces with limited durability. We propose a wearable microfluidic amperometric sensor featuring a spatially arranged three-electrode system (TES) for sweat glucose analysis. We optimize sensing electrodes' shape, size, spacing, and spatial arrangement through simulations and electrochemical measurements by comparing cyclic voltammogram behavior. The spatial TES is then designed based on the geometry of the microfluidic chamber, and the sensor is fabricated using a combination of laser cutting, screen printing, and layer-by-layer assembly techniques. The wearable microfluidic amperometric glucose sensor exhibits excellent linearity and specificity in in-vitro characterization. Additionally, it achieves comparable detection sensitivity (approximately 7.2 μA/mM) relative to sensors utilizing nanomaterials. By continuously analyzing glucose variations in sweat samples from the subject's abdomen, we validate the reliability and practicality of this device for real-time monitoring of sweat glucose.