Analysis of capacitive variation using parallel-plates method

Capacitive variation of capacitive sensor was analyzed by using two parallel plates coated by 0.4 mm- thick nylon and fixed together by resin to maintain the distance of those two plates at 2.5 mm and 5 mm. In this study, stainless and copper were used for development of capacitive sensor. In this paper ethyl alcohol solution is used as a case study. Ethyl alcohol solution with the concentration ranging from 95% to 5% with 10% step decrease of concentration diluted by distilled water was experimented under the controlled temperature of 23degC and the frequency was varied from 100 Hz to 2 kHz with 500 Hz interval. The capacitive variation analyzed from the equivalent circuit which was obtained from the developed sensor was then compared to the electrical circuit obtained from the Good Will R-L-C instrument model CRT to analyze for the appropriate material and the distance between two parallel plates (d) of the sensor. This proposed methodology was developed with consideration of the simple design for easy fabrication and low costs with high accuracy and reliability of the results.