One-Side-Electrode-Type Fluidic-Based Capacitive Pressure Sensor

This paper presents the development of a novel one-side-electrode-type fluidic-based capacitive pressure sensor. A pressure sensor using a one-side-electrode and an implementation of electrical double layer capacitance concept was proposed. Mechanical analysis of the membrane was carried out using the finite-element analysis in terms of deflection and Mises stress. A sensor with a circular membrane radius of 3.2 mm, membrane thickness of 0.8 mm, microchannel thickness of 0.5 mm, and microchannel width of 0.5 mm was fabricated using polydimethylsiloxane. The validation was made between the analytical and experimental results for fluid mechanisms inside the sensor. This showed that the displacement for all types of liquid, including methanol, ethanol, and silicon oil was linearly aligned. Methanol was chosen as an electrolyte due to its liquid properties, such as low surface tension and dielectric permittivity. From the experimental results, the operating frequency, response time, and sensitivity of the sensor were 1.2 kHz, 0.12 s, and 0.77 pF/kPa, respectively. The effects of vibration, temperature, and lifetime were also discussed in this paper.