Figure 3.

Typical characteristics of the pressure sensor. (a) Capacitance response in pressure region from 0.1 Pa to 53 kPa. (b) Stepped increase associated with the accumulation process of five dandelion seeds on the sensor. (c) Comparison of the maximum sensitivity and LOD between the proposed sensor and capacitive pressure sensors reported in the literature. (d) Repeatable response under periodical pressures of 1.5 kPa, 2 kPa, 8 kPa, 14.5 kPa, and 30 kPa. (e) Durability test results after 5000 loading and unloading cycles at a pressure of 10 kPa, showing no degradation in the relative capacitance change. (f) The stable capacitance response under pressure of 10 kPa in the environment with the humidity of 30%, 45%, 60%, and 75%. (g) Capacitance response of the sensor to sound waves of 80 dB generated form a conventional speaker. (h) Human pulse signal curves tested by the sensor attached to the wrist. (i) Detection of micropressure under low and high pressures. (j) Capacitance response to a fallen water droplet of 10 μL, with the insets depicting the water droplet falling process.