Researchers Mojtaba Joodaki and Mehrdad Jafarian, affiliated with the University of Tehran, have developed a novel microwave oscillator sensor designed for liquid level detection. Their work, published in the IEEE Transactions on Microwave Theory and Techniques, presents a low-cost, high-precision sensor that could have significant implications for the energy industry, particularly in applications requiring accurate liquid measurement.
The sensor’s design incorporates an adjustable input resistance, achieved through the addition of a Z2 branch in the input network. This branch consists of a transmission line, a capacitor, and a resistor. The researchers tested the sensor with eight different liquids, each with varying dielectric constants, including water, IV fluid, milk, ethanol, acetone, petrol, olive oil, and Vaseline. By fine-tuning the Z2 branch, they established a clear relationship between the dielectric constant of the materials and the resistor value.
The sensor demonstrated remarkable linearity, with nonlinearity below 2.44%, and high accuracy, boasting an average sensitivity of 21 kHz/μm. Its limit of detection (LoD) was found to be less than 0.05 mm, indicating exceptional precision. The sensor also showed stability across a range of liquid temperatures and exhibited robust, repeatable behavior. Notably, the sensor’s ability to handle liquids with high dielectric constants makes it a superior choice over capacitive sensors for such applications.
For the energy industry, this sensor could be particularly useful in applications such as fuel level monitoring in vehicles or storage tanks, where accurate and reliable liquid measurement is crucial. The sensor’s affordability, compatibility with CMOS and MEMS technologies, and ease of fabrication make it an excellent choice for small-scale liquid detection applications. The researchers validated the sensor’s performance using water as a representative liquid and substantiated its improvement through both experimental results and theoretical analysis. This innovative sensor technology holds promise for enhancing the precision and efficiency of liquid level detection in various energy sector applications.
This article is based on research available at arXiv.