Design of a sensor using an axially symmetric metamaterial for precise detection of liquid samples

This paper introduces an axially symmetric metamaterial (MTM) designed for high-sensitivity liquid sensing in the microwave frequency range. The unit cell of the proposed MTM measures 25 mm × 25 mm, fabricated on an FR-4 substrate, exhibits dual resonances at 2.106 GHz and 3.387 GHz. This enables accurate detection of dielectric changes in aqueous urea solutions. The MTM sensor is numerically analyzed using CST Microwave Studio and experimentally validated through prototype measurements, representing good agreement between simulated and measured results. The sensing mechanism relies on resonance deviations caused by changes in the dielectric properties of aqueous urea solutions, resulting in excellent frequency shifts and improved sensitivity at both resonances. Compared with previously reported designs, the proposed sensor offers a promising blend of high sensitivity, simple geometry, and low fabrication cost. Owing to its symmetrical design and high sensitivity, the sensor has promising applications in industrial quality control and advanced sensing.