A constant phase impedance sensor for measuring conducting liquid level

Area of Science:

• Electrical Engineering
• Materials Science
• Sensor Technology

Background:

• Capacitive liquid level sensors face errors due to signal frequency fluctuations affecting capacitance.
• The double layer effect at the metal-insulator interface in polar media complicates accurate measurements.
• Minimizing parasitic capacitances is crucial for reliable capacitive sensor design.

Purpose of the Study:

• To propose and characterize a novel constant phase impedance sensor for measuring conducting liquid levels.
• To address the issue of input signal frequency fluctuation in capacitive liquid level sensing.
• To develop a simple, inexpensive, and stable sensor for liquid level measurement.

Main Methods:

• Development of a constant phase impedance sensor utilizing the phase angle change with liquid level.
• Characterization of sensor parameters including constant phase angle and fractional order.
• Interfacing the sensor with a phase detection circuit for voltage signal conversion.

Main Results:

• The novel sensor demonstrates stable output even with input frequency fluctuations.
• Achieved significant sensitivity of 2.1°/cm for conducting liquid level changes.
• The sensor operates effectively for liquid levels in the 0-4 cm range.

Conclusions:

• The proposed constant phase impedance sensor offers a stable and accurate solution for conducting liquid level measurement.
• This technology overcomes the frequency-dependent errors inherent in traditional capacitive sensors.
• The sensor's simple fabrication and cost-effectiveness make it a practical choice for various applications.