An experimental study of the fluids mechanism and effects of liquid for capacitive pressure sensor

This paper demonstrates the experiment for the capacitive pressure sensor for the fluid mechanism and effects of liquid to the sensor performance. The sensor using one side electrode was proposed with the implementation of electrical double layer capacitor. The sensor consisted of membrane and microchannel where it was fabricated using PDMS material. This sensor was able to measure the pressure below than 7 kPa. When the pressure was applied to the membrane, it gave deflection and the liquid inside the microchannel moved opposite the membrane. The liquid movement gives capacitance change to the sensor where it depends on the types of liquid used. The comparison was made between the experimental and analytical results for the liquid displacement inside the microchannel. In order to study the effect of liquid to the capacitance change, the methanol, ethanol and silicon oil were chosen. When related to the capacitance, the important factor for liquid is dielectric constant. It is proved that the methanol which has higher dielectric gives high performance compared to the ethanol and silicon oil. Given that the sensor sensitivity for the methanol and ethanol were 0.98 pF/kPa and 0.55 pF/kPa, respectively.