Fig. 4.

Pressure and proximity sensing performances and area expansion. a Capacitance response to various pressures for two consecutive load tests. b Real-time small-pressure recording during the sequential application of six water droplets to the sensor; the corresponding pressure is 7.3 ± 1.2 Pa. c Pressure mapping of a number “6” stamped on the pressure sensor array with a pressure of 8 kPa. d Capacitance changes from a finger cyclically approaching the device (green, from a distance of approximately 1 cm), pressing it (pink) and moving away (white). e The relative capacitance change reduces with the decreasing distance of an approaching finger. The inset shows the capacitance difference as a finger repeatedly approaches the device. f Proximity detection of a hand and identification of its position. g Schematic illustration of an SCMN as an artificial electronic skin on a hand, showing sensing adjustability and expandability (scale bar: 1 cm). h Pressure mapping before and after the 300% expansion of an SCMN; the position of the pressure load is also identified after expansion