fig3

Figure 3. A skin-interfaced miniaturized microfluidic device enabling real-time sweat analysis of four key nutrients (vitamin C, calcium, zinc, and iron) through colorimetric detection and transdermal nutrient delivery. (A-C) Illustration of the device architecture, microreservoir design, and wearable form factor; (D) Images of the device and the concentration of nutrients in sweat before and after sweating with subject#1; (E) Images of the device and the concentration of nutrients in sweat before and after sweating with subject#2; (F-I) Human trials with nutrient monitoring before and after patch application in two subjects and the associated quantitative colorimetric analysis via RGB and UV–Visual spectroscopy validating concentration-dependent responses across varying microreservoir depths, enabling accurate nutrient quantification in sweat. Reprinted with permission from^[85], Copyright 2021 Joohee Kim, Yixin Wu, Haiwen Luan, et al. Advanced Science published by Wiley-VCH GmbH. UV: Ultraviolet.