Wearable analytical platform for colorimetric detection of sweat lactate using spherical colloidal photonic crystal hydrogel

The construction of reliable and sensitive wearable sensors capable of monitoring specific targets in sweat remains a challenge highly relevant to a range of sensor/diagnostic applications. Herein, we develop a wearable microfluidic platform to monitor sweat lactate, in which spherical colloidal Photonic Crystal Hydrogel (PCH) is synthesized to construct the sensing part. Thanks to the structural color of PCH, lactate concentrations can be obtained via the eye-recognizable and low angle-dependent color variation. Accurate quantitative analysis is performed on a smart phone with Matlab code by integrating the linear relationship between hue value of sample photos and lactate concentrations. The developed sweat sensor presents good selectivity and long-term stability, and it is capable of detecting lactate accurately in human sweat within the physiological range. On-body measurement performed on volunteers successfully demonstrates the applicability of the developed device. This wearable analytical platform provides a promising tool for sweat lactate detection in sports science and medical diagnosis. And it is expected to contribute to developing user-friendly wearable biochemical sensor devices.