Extended Data Fig. 5: Optimization of carbagel iontophoresis for simultaneous sweat stimulation and paper-based microfluidic collection.
a, Schematic illustration of integrated iontophoresis with a paper-based microfluidic sweat collection channel. b, Total sweat volume collected by the paper-based microfluidic channel following iontophoretic stimulation using carbagel (black) and pilogel (red). n = 3. c, Current stability of the iontophoretic modules with different resistances. d, Simulation setup for estimating sweat volume, including the anode, cathode, and extended region for modeling carbachol diffusion within the skin (total current: 130 μA, duration: 10 min). Scale bar, 10 mm. Color bar in logarithmic scale. e, Sweat rate estimation model based on iontophoretically delivered carbachol concentration, using threshold concentrations for sweat initiation and maximum sweat rate. f, Experimental (red, black) and simulated data (blue) for total sweat volume collected at varying current densities (1% carbagel, 1.5 mm spacing). n = 3. g, Experimental sweat rate in two subjects over 40 min under carbagel stimulation at varying current densities. n = 3. h, Simulated sweat rate over 40 min at varying current densities. i-k, Top and cross-sectional views of the electrical field distribution in the iontophoretic module at current densities of 130 μA (i), 41 μA (j) and 19 μA (k). Color bar in logarithmic scale. l,m, Successful generation of sufficient sweat volume using the integrated iontophoresis system, paper-based microfluidic collection channel, and LFA. Scale bar, 5 mm. Data are presented as mean values ± SD (n = 3 technical replicates).
