An Ant-Nest-Structured Wearable Sensor with pH Calibration for Reliable Monitoring of Sweat Glucose

Sweat glucose detected by wearable sensors can serve as a potential reference factor for diabetes management. However, inefficient sweat collection and fluctuating sweat pH hinder the precise detection of glucose. Herein, we designed a wearable sensing system comprising an ant-nest-structured sensor and a pH-responsive microchannel with multiple sweat inlets to continuously and accurately monitor the glucose level in sweat. Compared with the traditional planar electrode, this internally interconnected biomimetic structure provided a large number of accessible pores for contact with glucose molecules and electrolytes, remarkably decreasing the diffusion resistance. Furthermore, due to the formation of adjacent distributed cascade sensing units, the electron transmission distance from the catalytic center to the electrode surface was shortened, and the inoperative diffusion of H₂O₂ in the sensor was also weakened. The microchannel could convey the perspiration from the epidermis to the sensing zone within 250 s, while the coated pH indicator in the microchannel monitors the liquid's pH in a colorimetric zone. As a result, our wearable sensor integrated with a pH-responsive microchannel accurately tracked the change of glucose levels in sweat before and after a diet, displaying reliable results after calibration similar to those of commercial colorimetric kits. In addition, a longitudinal investigation of the relationship between blood and sweat glucose from healthy people and diabetic patients revealed a good correlation in glucose between the two. Wearable biosensors for real-time noninvasive analysis of glucose in sweat may significantly facilitate diabetes management at home.