Extended Data Fig. 1: Devices with different types of structures and their performance under varying liquid pressure over multiple cycles.

a, Photo of a “lotus leaf sensor” and SEM image of the lotus leaf surface. b, c, Capacitance response of the “lotus leaf sensor” under varying liquid pressure over multiple cycles. The sensor showed unstable sensing performance with large thresholds and hysteresis. d, SEM image of a pillar-array structure. e, f, Capacitance response of a hydrophilic pillar-array device under varying pressure over multiple cycles. A saturation at small pressure occurred (< 5 kPa), and no unloading response was shown due to the irreversible wetting on the hydrophilic surface of the pillars after fully wetted. Contact angle of hydrophilic gold surface is measured as 60.9 ± 2.4°. This suggests that hydrophobic surfaces are essential to establish a pressure-sensitive air layer. g, Optical image of water-air interface in an ODT treated hydrophobic pillar-array structure, showing the non-uniform underwater wetting condition. h, i, Capacitance response of ODT treated hydrophobic pillar-array device under varying liquid pressure over multiple cycles. j, SEM image of a hexagon-array structure. k, l, Capacitance response of ODT treated hydrophobic hexagon-array structure sensor under varying liquid pressure over multiple cycles. The results showed that the repeatability between different cycles was greatly improved compared to the pillar-array structure sensor. Contact angle of hydrophobic gold/ODT surface is measured as 107.3 ± 0.5°.