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Figure 4. Soft microfluidic wearable patch for on-demand, longitudinal, and multianalyte sweat sensing. (A) Schematic images of the soft microfluidic device, (i) exploded view of the skin-interfaced device, illustrating multilayer components including adhesive backing, microfluidic channels, colorimetric assays, and pull-tab-activated pumps, (ii) Top-down image of the assembled device showing microchambers for targeted fluid delivery, (iii) pump actuation mechanism via manual tab pulling enables selective transport of sweat to designated sensing chambers, (iv) on-demand longitudinal analysis, (v) condition-specific configurations target kidney function, electrolyte imbalance, fitness, and inflammation, (vi) device mounted on a human forearm for on-body testing; (B) Study of sample distribution in sensing chambers using stacked cellulose membranes (0-4), revealing improved color uniformity visualized via 2D pixel intensity heatmaps; (C) (i-vii) Calibration curves of colorimetric assays for chloride, calcium, glucose, urea, creatinine, copper, and pH, respectively, showing RGB intensity values corresponding to concentration gradients. Reprinted with permission from^[87]. Copyright © 2022, American Chemical Society.