Compact and Highly Sensitive Bended Microwave Liquid Sensor Based on a Metamaterial Complementary Split-Ring Resonator

Abstract

In this paper, we present the design of a compact and highly sensitive microwave sensor based on a metamaterial complementary split-ring resonator (CSRR), for liquid characterization at microwave frequencies. The design consists of a two-port microstrip-fed rectangular patch resonating structure printed on a 20 × 28 mm2 Roger RO3035 substrate with a thickness of 0.75 mm, a relative permittivity of 3.5, and a loss tangent of 0.0015. A CSRR is etched on the ground plane for the purpose of sensor miniaturization. The investigated liquid sample is put in a capillary glass tube lying parallel to the surface of the sensor. The parallel placement of the liquid test tube makes the design twice as efficient as a normal one in terms of sensitivity and Q factor. By bending the proposed structure, further enhancements of the sensor design can be obtained. These changes result in a shift in the resonant frequency and Q factor of the sensor. Hence, we could improve the sensitivity 10-fold compared to the flat structure. Subsequently, two configurations of sensors were designed and tested using CST simulation software, validated using HFSS simulation software, and compared to structures available in the literature, obtaining good agreement. A prototype of the flat configuration was fabricated and experimentally tested. Simulation results were found to be in good agreement with the experiments. The proposed devices exhibit the advantage of exploring multiple rapid and easy measurements using different test tubes, making the measurement faster, easier, and more cost-effective; therefore, the proposed high-sensitivity sensors are ideal candidates for various sensing applications.

Microwave Resonators for Wearable Sensors Design: A Systematic Review

“…Looking forward at the further applications, ref. [108] proposes a highly sensitive microwave CSSR-based sensor for liquid characterization bent into a cylinder again of numerous radii, as illustrated in Figure 9. The results of the simulation and the experimental analysis conclude that the bending effect has a direct impact on the S 21 response and frequency in a way that the frequency band is notoriously widened for a lower radius in the case of 0% concentration of water, and it also increases the frequency range between minimum and maximum liquid concentrations for a smaller bending radius.…”

Metasurfaces for Sensing Applications: Gas, Bio and Chemical

“…Moreover, a metamaterial-based CSRR sensor was fabricated on Roger RO3035 substrate with a thickness of 0.75 mm, a relative permittivity of 3.5 and a loss tangent of 0.0015. To improve the sensitivity and Q factor, the chemical samples were introduced to a capillary glass tube placed in parallel to the sensor surface [129]. Figure 12a,b show the geometric features of the sensor and Figure 12c-e show the physical implementation.…”

Dual-Square-Split-Ring-Enclosed Microstrip-Based Sensor for Noninvasive Label-Free Detection

“…Different types of microwave sensors have been developed with different methodologies for sensing applications within the operating frequency range. For liquid characterization [ 10 ], a microstrip-fed rectangular patch antenna using a Rogers RO 3035 as a host medium with two port networks was presented where the capillary glass tube lay parallel to the surface of the sensor, where the large diversity of geometric orientation [ 11 ] of the chiral structure showed a new way to manufacture three-dimensional structures. The other methodology using metamaterial absorber technology was utilized to accumulate the electromagnetic signal with a silver-based metallic layer to form two concentric rings [ 12 ], which produced two narrow absorption peaks.…”