Fig. 2: Characterization of the flexible capacitive pressure sensor array.
a Structure diagram of the capacitive pressure sensor unit in the array. b Top-view scan electron microscopy (SEM) image of the fabricated PVA/H3PO4 film, showing a rough microstructured surface. c Capacitance-pressure response of the capacitive sensors with and without the microstructure. d Changes in capacitance value of the pressure sensor under five loading and unloading pressure stimuli of 0.8, 1.6, 2.4, 3.2, and 4 kPa. e Changes in capacitance value of the pressure sensor under the sequential loading pressure stimuli of 0.8, 1.6, and 2 kPa over eight seconds. f Dynamic capacitance-pressure response. The response time and recovery time are 110 ms and 190 ms, respectively. g Cyclic loading and unloading test under a maximum pressure stimulus of 1.2 kPa. h Capacitance-pressure response of all nine sensor units in the array. The applied pressure ranges from 0 to 4 kPa.
