A new compound sensor for optical, electrical and ultrasonic measurements in the liquid

In this paper, a compound sensor is proposed for the measurement of ingredient concentration in liquid. In the proposed sensor, the optical property is measured by a light emitting diode (LED) and a phototransistor. In addition, the electrical and ultrasonic properties are measured by PVDF(polyvinylidene fluoride) films, which each electrode is constructed by the transparent conductive electrode (ITO electrode), arranged on the surfaces of the LED and phototransistor. In the experiment, the liquid with yellow color, ethanol and NaCl concentrations in distilled water was prepared, and the optical, electrical and ultrasonic properties of the liquid were measured by the proposed sensor. The result suggested that it was possible to measure three kinds of concentrations in the liquid by using the proposed sensor.