Fig. 1. (Color online) A three-dimensional liquid diode for soft, integrated permeable electronics^[16]. (a) Schematic of the integrated system-level sweat-permeable electronics, consisting of permeable electrodes, 3D-LD, and flexible circuit board. Blue arrow indicates the pathway of the sweat from the skin to the outlet. The exploded view illustrates the unidirectional sweat transport through the electrode, VLD, and HLD. (b) Cross-sectional representation of the 3D-LD, demonstrating unidirectional sweat transport from the skin–device interface to the outlet. (c) Design of serpentine interconnects to facilitate open channels above sweat pores. Scale bar, 0.5 mm. (d) Permeable electrode maintains stable conformal contact on the fingertip under perspiration conditions. Scale bar, 2 mm. (e) Mechanism of the unidirectional sweat transport in the VLD and photograph of the VLD in the sweat-wicking state. Scale bar, 5 mm. (f) Unidirectional sweat-transport mechanism in the HLD and scanning electron microscopy images of the supporting structure. Scale bar, 300 μm. (g) Comparison of PDMS membrane and 3D-LD in terms of gas and sweat permeability. Scale bars, 0.5 cm. (h) Adhesion strength between patches and skin at different time intervals during exercise. Points, mean; error bars, s.d.; n = 3 independent tests. (i) Water vapor transmission rate (WVTR) of the commercial ECG electrode, PDMS, VLD, and 3D-LD. Bar height, mean; error bars, s.d.; n = 5 independent samples. (j) ECG signals recorded from different electrodes before and after exercise. (k) Exploded-view illustrations of the skin-integrated devices featuring a detachable design, highlighting key layers. (l) Photographs of the permeable textile-integrated weather station. Scale bars, 5 cm ( ⅰ ), 2 cm ( ⅱ ).