Planar Microwave Sensors for Accurate Measurement of Material Characterization: A Review

Microwave sensor is used in various industrial applications and requires highly accurate measurements for material properties. Conventionally, cavity waveguide perturbation, free-space transmission, open-ended coaxial probe, and planar transmission line technique have been used for characterizing materials. However, these planar transmission lines are often large and expensive to build, further restricting their use in many important applications. Thus, this technique is cost effective, easy to manufacture and due to its compact size, it has the potential to produce sensitivity and a high Q-factor for various materials. This paper reviews the common characteristics of planar transmission line and discusses numerous studies about several designs of the microstrip resonator to improve the sensor performance in terms of the sensitivity and accuracy. This technique enables its use for several industrial applications such as agriculture and quality control. It is believed that previous studies would lead to a promising solution of characterizing materials with high sensitivity, particularly in determining a high Q-factor resonator sensor

A Miniaturized and Highly Sensitive Microwave Sensor Based on CSRR for Characterization of Liquid Materials

In this work, a miniaturized and highly sensitive microwave sensor based on a complementary split-ring resonator (CSRR) is proposed for the detection of liquid materials. The modeled sensor was designed based on the CSRR structure with triple rings (TRs) and a curve feed for improved measurement sensitivity. The designed sensor oscillates at a single frequency of 2.5 GHz, which is simulated using an Ansys HFSS simulator. The electromagnetic simulation explains the basis of the mode resonance of all two-port resonators. Five variations of the liquid media under tests (MUTs) are simulated and measured. These liquid MUTs are as follows: without a sample (without a tube), air (empty tube), ethanol, methanol, and distilled water (DI). A detailed sensitivity calculation is performed for the resonance band at 2.5 GHz. The MUTs mechanism is performed with a polypropylene tube (PP). The samples of dielectric material are filled into PP tube channels and loaded into the CSRR center hole; the E-fields around the sensor affect the relationship with the liquid MUTs, resulting in a high Q-factor value. The final sensor has a Q-factor value and sensitivity of 520 and 7.032 (MHz)/Er) at 2.5 GHz, respectively. Due to the high sensitivity of the presented sensor for characterizing various liquid penetrations, the sensor is also of interest for accurate estimations of solute concentrations in liquid media. Finally, the relationship between the permittivity and Q-factor value at the resonant frequency is derived and investigated. These given results make the presented resonator ideal for the characterization of liquid materials.Publicad

Review of recent microwave planar resonator-based sensors: Techniques of complex permittivity extraction, applications, open challenges and future research directions

Recent developments in the field of microwave planar sensors have led to a renewed interest in industrial, chemical, biological and medical applications that are capable of performing real-time and non-invasive measurement of material properties. Among the plausible advantages of microwave planar sensors is that they have a compact size, a low cost and the ease of fabrication and integration compared to prevailing sensors. However, some of their main drawbacks can be considered that restrict their usage and limit the range of applications such as their sensitivity and selectivity. The development of high-sensitivity microwave planar sensors is required for highly accurate complex permittivity measurements to monitor the small variations among different material samples. Therefore, the purpose of this paper is to review recent research on the development of microwave planar sensors and further challenges of their sensitivity and selectivity. Furthermore, the techniques of the complex permittivity extraction (real and imaginary parts) are discussed based on the different approaches of mathematical models. The outcomes of this review may facilitate improvements of and an alternative solution for the enhancement of microwave planar sensors’ normalized sensitivity for material characterization, especially in biochemical and beverage industry applications

High Quality Factor Using Nested Complementary Split Ring Resonator For Dielectric Properties Of Solids Sample

A Nested complementary split ring resonator (CSRR) was proposed based on planar structure. The main objective of this work is to get a higher quality factor (Q-factor) with minimal error detection of complex permittivity. The sensor operated at the 3.37GHz resonant frequency and simulated by ANSYS HFSS software. Subsequently, the designed sensor has been fabricated and tested with the presence of several material under test (MUTs) placed over the sensor. The result achieved high unloaded Q-factor, 464. There has been proof of good agreement concerning the results between theoretical, simulation, and measured parameters of error detection, which is below 13.2% real part permittivity and 2.3% the loss tangent. The proposed sensor is practically useful for the food industry, bio-sensing, and pharmacy industry applications

Electrical Equivalent Model Of Symmetrical Split Ring Resonator Sensor-Based Microwave Technology

In this paper, a microwave planar sensor based on symmetrical split ring resonator (SSRR) is investigated. This sensor uses ring resonator with slits at 0o and 180o angles as method to realize the harmonic resonant frequency response and then, it integrated with symmetrical split ring for suppressing the undesired harmonic spurious. Compact size, simplicity, cost effective, and ease of fabrication are the main advantage of SSRR sensor. The model of analytical equivalent circuit is proposed and the characteristic of band-pass and band-stop are derived and investigated for the analysed SSRR with/without spurliners filters. The performance and sensitivity of the SSRR sensor is high with an average accuracy between 96% to 98 % at narrow band frequencies. This type of resonators sensors can detect the material properties under their chemical or physical changes which is essential for numerous applications such as quality control, agriculture, bio-sensing, medicine and pharmacy, food industry, and material science

A Compact and Low-Profile Curve-Feed Complementary Split-Ring Resonator Microwave Sensor for Solid Material Detection

A compact and low-profile curve-feed complementary split-ring resonator (CSRR) microwave sensor for solid material detection is presented in this article. The curve-feed CSRR sensor was developed based on the CSRR configuration with triple rings (TRs) designed together, utilizing a high-frequency structure simulator (HFSS) microwave studio. The designed curve-feed CSRR sensor resonates at 2.5 GHz, performs in transmission mode, and senses shift in frequency. Four varieties of the sample under tests (SUTs) were simulated and measured. These SUTs are Air (without SUT), Roger 5880, Roger 4350, FR4, and detailed sensitivity analysis is being performed for the resonant band at 2.5 GHz. The finalized CSRR curve-feed sensor was integrated with defective ground structure (DGS) to deliver high-performance characteristics in microstrip circuits, which leads to a high Q-factor magnitude. The presented curve-feed sensor has a Q-factor of 520 at 2.5 GHz, with high sensitivity of about 1.072. The relationship between loss tangent, permittivity, and Q-factor at the resonant frequency has been compared and discussed. These disseminated outcomes make the suggested sensor ideal for characterizing solid materials

Review of Recent Microwave Planar Resonator-Based Sensors: Techniques of Complex Permittivity Extraction, Applications, Open Challenges and Future Research Directions

Recent developments in the field of microwave planar sensors have led to a renewed interest in industrial, chemical, biological and medical applications that are capable of performing real-time and non-invasive measurement of material properties. Among the plausible advantages of microwave planar sensors is that they have a compact size, a low cost and the ease of fabrication and integration compared to prevailing sensors. However, some of their main drawbacks can be considered that restrict their usage and limit the range of applications such as their sensitivity and selectivity. The development of high-sensitivity microwave planar sensors is required for highly accurate complex permittivity measurements to monitor the small variations among different material samples. Therefore, the purpose of this paper is to review recent research on the development of microwave planar sensors and further challenges of their sensitivity and selectivity. Furthermore, the techniques of the complex permittivity extraction (real and imaginary parts) are discussed based on the different approaches of mathematical models. The outcomes of this review may facilitate improvements of and an alternative solution for the enhancement of microwave planar sensors’ normalized sensitivity for material characterization, especially in biochemical and beverage industry applications