An Efficient Measurement Technique Incorporating an Impedimetric Sensor Inside a Phase-Shift-Oscillator Loop

In this work, we propose a circuit named as impedimetric oscillator for measuring the phase change of impedimetric sensors. Architecturally, a sensor pair is incorporated within the oscillator loop in such a way that the oscillator’s output frequency depends on the relative phase of the sensor pair. Furthermore, by keeping one of the sensor pairs in a reference solution, we can test the measurand by dipping the second sensor into it. The output frequency of the oscillator depends on the condition of the test medium with respect to the reference medium. It is obvious that the circuit is capable of measuring the absolute phase angle of a sensor element if a resistor is used as the second element. Moreover, the oscillator has the flexibility to tune its quiescent frequency to be suitable for the sensor pair. The proposed oscillator has been analyzed and simulated in LTSpice. A breadboard-based prototype is implemented in hardware to carry out experiments. The experimental results are consistent with the simulated and analytical results.