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.
Kexin Fan,Jiayang Zeng,Chenyu Yang,Gonglei Wang,Kai Lian,Xiuhong Zhou,Yaping Deng,Guozhen Liu
Uric acid (UA) is an important biomarker for many diseases. A sensitive point-of-care (POC) testing platform is designed for the digital quantification of salivary UA based on a colorimetric reaction on an easy-to-build smartphone-assisted microfluidic paper-based analytical device (SμPAD). UA levels are quantified according to the color intensity of Prussian blue on the SμPAD with the aid of a MATLAB code or a smartphone APP. A color correction method is specifically applied to exclude the light effect. Together with the engineering design of SμPADs, the background calibration function with the APP increases the UA sensitivity by 100-fold to reach 0.1 ppm with a linear range of 0.1–200 ppm. The assay time is less than 10 min. SμPADs demonstrate a correlation of 0.97 with a commercial UA kit for the detection of salivary UA in clinical samples. SμPADs provide a sensitive, fast, affordable, and reliable tool for the noninvasive POC quantification of salivary UA for early diagnosis of abnormal UA level-associated health conditions.