Design of Thin Film Capacitive Sensor for Flow Measurement

We report the design methodology of thin film capacitor (TFC) device using thermal evaporation technique for quality study or material differentiation application by testing with liquid (different concentration) and solid. A simple and special modification was incorporated in thermal evaporation setup for depositing semi cylindrical capacitor design on a capillary tube (CT). In order to avoid the disturbance due to electrostatic noise disturbance, TFC was covered with another glass tube, aluminum (Al) metal foil (as shield) and finally by plastic tube cover. Electrodes were taken from the film using silvers paste and connected as input to the LCR-Z meter. The capacitance value of the thin film was varied up to 15-16 pF from the initial value (Al: 129 pF, Cu: 130 pF) when subjected to the static flow. A low cost embedded micro controller module with Liquid Crystal Display (LCD) was developed for the real time testing of TFC.