Thin film capacitor for void fraction measurement in a two-phase system

This paper describes a two phase flow sensor using copper (Cu) thin film electrodes. A two phase flow constitutes a simultaneous flow of two different phases. To identify these phases in an air-water flow in a small diameter tube, Cu films were coated on to glass substrate at various substrate temperatures using dc magnetron sputtering technique. The films were characterized for their structural, morphological and electrical properties using X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM) and resistance/capacitance measurement by LCR-Z meter. The grain size of the films increased with increase in the substrate temperature, which in turn reduced the defects. Due to this the resistance of the films decreased. The fabricated capacitor using the Cu film, exhibited different capacitance values with respect to the flow of fluid in the capillary tube.