Fig. 3: Skin adaptability of organohydrogel nanofilms.

A Young‑equation diagram defining the contact angle (\({{{{\rm{\theta }}}}}_{{{{\rm{c}}}}}\)) between artificial sweat and the film and the three interfacial tensions \({{{{\rm{\gamma }}}}}_{{{{\rm{LG}}}}}\) (liquid-gas), \({\,{{{\rm{\gamma }}}}}_{{{{\rm{SL}}}}}\) (solid-liquid), and \({\,{{{\rm{\gamma }}}}}_{{{{\rm{SG}}}}}\) (solid-gas). B Schematic of simultaneous heat and sweat transport: perspiration‑saturated skin (≈100% RH, 37 °C) drives liquid, vapor, and heat through the film toward the cooler, drier ambient (25 °C, 30% RH) until equilibrium is reached. C Experimental setup for contact‑angle measurements. The organohydrogel nanofilm is sealed over a 4 mm aperture in a glass slide, and an artificial‑sweat droplet is monitored from the opposite side. Schematics in A–C were created in BioRender. Zheng, M. (2025) https://BioRender.com/a1k3zuj. D Representative snapshots of droplets on commercial gel, PDMS film, and organohydrogel films of decreasing thickness, inverted droplets indicate full permeation. E Samples exhibiting negative contact angles indicate permeability. The negative contact angle represents the angle measured on the permeation side of the samples. F Infrared images of the three patches (commercial gel, PDMS film, and organohydrogel nanofilm) on a volunteer’s chest before running and after 10 and 20 min of exercise. Scale bar, 2 cm. G Temperature rise under each patch (\(\triangle T={T}_{C}-{T}_{S}\)) extracted from (F). The organohydrogel nanofilm remains thermally indistinguishable from bare skin. H Air permeance of organohydrogel nanofilms as a function of thickness and temperature. A 3 µm-thick parylene film is plotted for reference. I WVTR of organohydrogel films with varied thicknesses and different temperatures. J Skin-electrode contact impedance during 20 min running followed by 100 min rest for human skin, organohydrogel nanofilm‑covered skin, and commercial gel‑covered skin. The organohydrogel nanofilm recovers to its baseline impedance, whereas the gel fails after detachment. Data represent means ± SD (n =  3 samples) for G and J. Source data are provided as a Source Data file.