Metamaterial-based Sensor Research Articles

Chiral metamaterial-based sensor applications to determine quality of car lubrication oil

Motor oils have to be changed periodically in a period of 10.000–20.000 km according to the motor types. A chiral metamaterial sensor that operates in X band is developed to determine the quality of motor oils, numerically analyzed and experimentally tested in this study. The proposed design has square and circular shaped resonators that are printed on IS680 substrate. Reflection coefficient parameters of S11 and S22 are employed for the verification of sensor. The physical principle behind the structure in this study is based on the degradation of motor oil, which changes dielectric constant and causes resonance frequency shifts. According to S11 reflection coefficient data, 40 MHz(0 km–10000 km) and 60 MHz(0 km–5000 km) resonant frequency shifts are observed between clear and dirty motor oils samples. These shifts have the values of 30 MHz(0 km–10000 km) and 120 MHz(0 km–5000 km), when we look at S22. The simulated and experimental study results are complying with each other. The novel side of this study is to have high sensitivity and higher quality factor when it is compared with similar study results. Furthermore, no such studies have been conducted so far in the literature.

Design of highly sensitive complementary metamaterial‐based microwave sensor for characterisation of dielectric materials

Metamaterial-based double-slit complementary split rectangular resonator sensor is proposed for the characterisation of dielectric properties of the materials under test (MUTs). The proposed sensor is designed and simulated on the CST microwave studio software using a low-cost substrate FR4. An array of three identical resonators is etched in the ground plane of the sensor to achieve a single and deep notch of −58.7 dB in the transmission coefficient (S 21) at the resonant frequency of 7.01 GHz, which is the novelty of the proposed sensor. A deep and single resonant frequency band has a significant role in the precise measurement of the dielectric properties of the MUTs. The effective constitutive parameters are extracted from the S-parameters. An equivalent circuit model is suggested that describes the overall behaviour of the sensor. The sensor is fabricated on the FR4 substrate and measured through the vector network analyser (N5224B) by placing the standard materials. The parabolic equation for the proposed sensor is formulated to approximate the permittivity of the MUTs. A very small percentage of error, 0.77, is found which shows high accuracy of the sensor. This methodology is efficient, simple in fabrication, and reduces cost and computational time also.

Design and study of a metamaterial based sensor for the application of liquid chemicals detection

The detection of chemical samples having close dielectric response is a big challenge as the detection principle is driven by the variations in the dielectric parameters of the investigated samples. In the current work, a new metamaterial-based sensor is designed and fabricated in order to be used for the detection of liquid chemicals in the frequency range from 8 to 12 GHz. Several designs were tested using genetic algorithm, which is embedded in the CST microwave studio, in order to optimize the desired dimensions of the resonator. The simulation and experimental results showed that the proposed sensor is working well to detect various liquids, including (i) clean and waste transformer oils, (ii) corn, cotton and olive oils, (iii) branded and unbranded diesels and (iv) aniline doped ethyl-alcohol and benzene doped carbon tetrachloride. This was made possible through the occurrence of a shift in the resonant frequency of about 250 MHz, 200 MHz, 250 MHz, 150 MHz and 50 MHz for the aforementioned samples, respectively. The sensing mechanism was interpreted through the surface current and electric field distributions. We believe that the proposed sensor is viable to be used in various applications including liquid chemicals detection and industrial applications.

Metamaterial-based sensor with a polycarbonate substrate for sensing the permittivity of alcoholic liquids in a WR-229 waveguide

The design, modeling and experimental confirmation of a metamaterial-based dielectric sensor on a 0.012λ0-thick (λ0 denoting middle free-space excitation wavelength) transparent and flexible substrate is reported at microwave frequencies. A handcrafted hard foam is implemented in front of the metamaterial inside the WR-229 waveguide to be filled with liquid mixtures in order to predict the complex permittivity. The variation of the volume ratio of the mixture caused a significant shift in the resonance frequencies. A first-order model between the resonance characteristics and complex permittivity is employed to determine the complex permittivity of ethanol-water and methanol-water mixtures at various volume ratios. The remarkable agreement between the predicted complex permittivity values from the measurement and the standardized values from the literature proves the validity of the employed model. The proposed sensor renders a practical, cost-effective and non-contact solution for determining the properties of unknown liquid mixtures.

The Detection of Chemical Materials with a Metamaterial-Based Sensor Incorporating Oval Wing Resonators

The detection of branded and unbranded chemical materials is essential for the quality control assessment. In this work, a metamaterial inspired sensor is designed and fabricated, which incorporates oval-shaped wing resonators, in order to use to detect branded and unbranded diesels in the X-band frequency region. The simulation studies were carried out by using the Computer Simulation Technology (CST) Microwave studio. A transmission line was introduced into the sensor design and genetic algorithm was used to optimize the proposed structure. Parametric study was investigated by changing the permittivity, permeability of the sensor layer, width of the transmission line, materials of the substrate layer, and width of the resonator. Results showed that different factors can be considered to sense the chemical materials including the shift in resonant frequency and amplitude variation in the reflection or transmission spectrum. It was found that the sensible variation in the transmission value is about −3.2 dB, which is superior to that reported in literature. It was concluded that the sensor is highly sensitive to distinguish the branded diesel from the unbranded one, which makes it viable for detecting fluidics in the chemical industry and medicine.

Microfluidic sensor applications by using chiral metamaterial

Chiral metamaterial-based sensor is designed for sensing the change in substance ratio of chemical substances when combined with distilled water. These samples have been prepared with 10%, 50% and 90% volume fraction of methanol, ethanol, acetone, ammonia and isopropyl alcohol. The complex permittivity of the prepared samples has been measured by Agilent 85070E dielectric probe kit and compared with the simulations. In the proposed design, linear shifts with the frequency bands of more than 100 MHz are observed in different measurements. For different material sensing, pure samples have been used and their reflection coefficient measurement results have been presented. Unique side of this study is that the structure provides very clear and sensitive results and presents a new approach to the microfluidic sensor applications by using the sample holder.

Design of metamaterial-based compact and highly sensitive microwave liquid sensor

This article presents the design of a compact and highly sensitive mu-negative metamaterial-based microwave sensor for liquid characterization. In the current state-of-the-art development, miniaturization and high sensitivity are the prime concern for designing microwave sensing devices. Hence, the liquid sensor has been developed with the aim to achieve compactness and high sensitivity. This has been realized by introducing a square spiral metamaterial configuration that aids to accomplish notable compactness of the device as well as establishes remarkable sensitivity within a small cross-sectional area. Initially, the sensing characteristic of the device has been verified using the least square method. It is followed by the development of two non-linear equations to calibrate the proposed sensor, which would help to calculate the permittivity of unknown analytes. The high sensitivity and the compactness of the proposed sensor make it an ideal candidate for chemical analysis in various applications.

Microfluidic Sensor Based on Composite Left-Right Handed Transmission Line

In this paper, we propose a novel metamaterial-based microfluidic sensor that permits the monitoring of properties of the fluid flowing in the microfluidic reservoir embedded between the composite left–right handed (CLRH) microstrip line and the ground plane. The sensor’s working principle is based on the phase shift measurement of the two signals, the referent one that is guided through conventional microstrip line and measurement signal guided through the CLRH line. At the operating frequency of 1.275 GHz, the CLRH line supports electromagnetic waves with group and phase velocities that are antiparallel, and therefore the phase “advance” occurs in the case of CLRH line, while phase delay arises in the right-handed (RH) frequency band. The change of the fluid’s properties that flow in the microfluidic reservoir causes the change of effective permittivity of the microstrip substrate, and subsequently the phase velocity changes, as well as the phase shift. This effect was used in the design of the microfluidic sensor for the measurement of characteristics of the fluid that flows in the microfluidic reservoir placed under the CLRH line. The complete measurement system was developed including the Wilkinson power divider that splits the signal between conventional RH and CLRH section, transmission lines with the microfluidic reservoirs, and a detection circuit for phase shift measurement. Measurement results for different fluids confirm that the proposed sensor is characterized by relatively high sensitivity and good linearity (R2 = 0.94). In this study, the practical application of the proposed sensor is demonstrated for the biomass estimation inside the microfluidic bioreactors, which are used for the cultivation of MRC-5 fibroblasts.

Rapid and label-free metamaterial-based biosensor for fatty acid detection with terahertz time-domain spectroscopy.

A rapid method for detecting fatty acids (FAs) using terahertz time-domain spectroscopy (THz-TDS) technology combined with a metamaterial-based THz sensor was developed. We measured the THz responses to oleic acid, linoleic acid and α-linoleic acid with different numbers of double-bond, α-linoleic acid and γ-linoleic acid with different conformations. In addition, in order to explore the reason for the observed redshifts of the resonance frequencies of the four FAs, the dielectric constants of the FAs were measured in the THz region. Furthermore, the four fatty acids were also attempted to be identified by Raman spectroscopy, which was difficult to accomplish unambiguously because of the effect of fluorescence. This result thus demonstrates the power and usefulness of metamaterial-assisted THz-TDS in the rapid determination of the FAs, and its potential as a versatile tool for investigation of biological metabolism, and for food product quality, safety inspection and control.

Label-free self-referenced sensing of living cells by terahertz metamaterial-based reflection spectroscopy.

Terahertz (THz) metamaterial-based reflection spectroscopy is proposed for label-free sensing of living cells by a self-referenced method. When sensing the living Madin-Darby canine kidney cell monolayer and phosphate buffered saline solution, self-referenced signals showed significant differences in peak intensity because of inherent discrepancy in the imaginary part of their complex refractive indices, as confirmed by 3D-FDTD simulations. The resonance peak intensity was unaffected by cell monolayer thickness variation, demonstrating feasibility for sensing various cells. Simulations and experiments showed that saponin-induced changes in cell permeability could be monitored in real-time. The self-referenced signal was linearly dependent on the adherent cell density, illustrating a label-free in situ THz metamaterial-based cell sensor.

Microwave Sensor for Liquid Dielectric Characterization Based on Metamaterial Complementary Split Ring Resonator

A metamaterial-based microwave sensor with complementary split ring resonator (CSRR) is implemented for dielectric characterization of liquids. The novelty in the proposed contactless sensor is the use of liquid samples placed normal to the sensor surface. Placed inside of glass capillary tubes, it is quickly possible to analyze the dielectric properties of liquids simply by replacing the capillary tubes with new samples. The liquid samples inside the glass capillary tubes modify the resonant frequency and $Q$ -factor of the CSRR sensor. Thereby, a relation between the sensor resonant frequency, $Q$ -factor, and complex permittivity of the liquid samples can be estimated. A measurement setup was used to test the proposed sensor that exhibited successfully detection of 10% steps in binary mixtures of ethanol and water. The proposed sensor is compact, low cost, contactless, reusable, easily fabricated, and easy to work.

Metamaterial-based fluid sensor for identifying different types of fuel oil samples

In this paper, we present, design and analyze a metamaterial (MTM) based sensor to distinguish different types of gasoline and diesel samples. Electromagnetic characterization of the samples is completed experimentally and the obtained data is used in the numerical analysis and in the design of the proposed sensor. Unlike the other studies performed in the literature, this structure offers a highly efficient sensing ability and operates in x-band frequency regime. The designed structure is fabricated and the experimental studies are carried out in the related frequency range. It is also demonstrated that numerical results are in a good agreement with the measurement results. The proposed sensor has highly enough bandwidth to sense the fuel oil samples including gasoline and diesel with different characteristics. The suggested structure can be used effectively as a fuel oil sensor in automotive industry. Besides, due to its simple design and high efficiency, the proposed structure can be adjusted to any other liquid sensing application in any desired frequency band by simple adjustments on the dimensions of the structure.

Metamaterial-based multifunctional sensor design for moisture, concrete aging and ethanol density sensing applications

We have designed and developed a metamaterial (MTM)-based multipurpose sensor structure capable of sensing moisture, liquid (ethyl alcohol-ethanol-in our case) density in pure water and the concrete aging. The structure is composed of a rectangular shape MTM cell resonator which can be adjusted to any desired frequency range depending on the application area and the material to be sensed. The material is put into a plastic rectangular pipe placed in a hole located in the middle of the structure. Depending on the response of the proposed model to the electromagnetic properties of the material under test (MUT), overall resonance frequency shifts providing the information to accurately estimate the soil moisture, concrete age and density rate of the sensed liquid samples in real time. The resonance frequency has been carefully chosen so that the MUT has a linear variation in its electromagnetic response behaviors. It is aimed for future studies to adjust the structure for designing a portable multipurpose sensor device and even adjust it to smart phones and sense the materials by simply using smart phones and a small amount of sample in high efficiency.

Microwave Metamaterial-Based Sensor for Dielectric Characterization of Liquids.

This article proposed to build a system founded on metamaterial sensor antennas, which can be used to evaluate impurities in aqueous substances according to the quality of transmission between the sensor antennas. In order to do this, a dedicated setup with tests in several frequencies was deployed so as to monitor the behavior of transmission variation between sensors. These sensors are microstrip antennas with a ground plane of resonant cleaved metallic rings; the substrate functions as a metamaterial for the irradiating element. In this study, an analysis was made of transmission between the sensors, looking for variation in angles of incidence of signal and of distance between the antennas. The sensor was tested at various operating frequencies, as such 1.8 GHz, 2.4 GHz, 3.4 GHz and 4.1 GHz, resulting in different values of sensitivity. The prototypes were constructed and tested so as to analyze the dielectric effects of the impurities on NaCl and C2H4O2 substances. The research aims to use these control systems of impurities in industrial premises.

A Microwave Method for Dielectric Characterization Measurement of Small Liquids Using a Metamaterial-Based Sensor.

We present a microwave method for the dielectric characterization of small liquids based on a metamaterial-based sensor The proposed sensor consists of a micro-strip line and a double split-ring resonator (SRR). A large electric field is observed on the two splits of the double SRRs at the resonance frequency (1.9 GHz). The dielectric property data of the samples under test (SUTs) were obtained with two measurements. One is with the sensor loaded with the reference liquid (REF) and the other is with the sensor loaded with the SUTs. Additionally, the principle of extracting permittivity from measured changes of resonance characteristics changes of the sensor loaded with REF and SUTs is given. Some measurements were carried out at 1.9 GHz, and the calculated results of methanol–water mixtures with different molar fractions agree well with the time-domain reflectometry method. Moreover, the proposed sensor is compact and highly sensitive for use of sub-wavelength resonance. In comparison with literature data, relative errors are less than 3% for the real parts and 2% for the imaginary parts of complex permittivity.

Terahertz sensing of highly absorptive water-methanol mixtures with multiple resonances in metamaterials

Terahertz sensing of highly absorptive aqueous solutions remains challenging due to strong absorption of water in the terahertz regime. Here, we experimentally demonstrate a cost-effective metamaterial-based sensor integrated with terahertz time-domain spectroscopy for highly absorptive water-methanol mixture sensing. This metamaterial has simple asymmetric wire structures that support multiple resonances including a fundamental Fano resonance and higher order dipolar resonance in the terahertz regime. Both the resonance modes have strong intensity in the transmission spectra which we exploit for detection of the highly absorptive water-methanol mixtures. The experimentally characterized sensitivities of the Fano and dipole resonances for the water-methanol mixtures are found to be 160 and 305 GHz/RIU, respectively. This method provides a robust route for metamaterial-assisted terahertz sensing of highly absorptive chemical and biochemical materials with multiple resonances and high accuracy.

Nonlinear damage detection and localization via an innovative metamaterial-based sensor

In recent years, acoustic metamaterials have attracted increasing scientific interest for very diverse technological applications ranging from sound abatement to ultrasonic imaging, mainly due to their ability to act as band-stop filters. At the same time, the concept of chaotic cavities has been recently proposed as an efficient tool to enhance the quality of nonlinear signal analysis, particularly in the ultrasonic/acoustic case. The goal of the present work is to merge the two concepts to propose a metamaterial-based device that can be used as a natural and selective linear filter for the detection of signals resulting from the propagation of elastic waves in nonlinear solids, e.g., in the presence of damage, and as a detector for the damage itself in time reversal experiments. Numerical simulations and experimental measurements based on scanning laser Doppler vibrometer demonstrate the feasibility of the approach and the potential of the device in providing improved signal to noise ratios and enhanced focusing on scatterer locations.

Plasmonic Metamaterial Sensor with Ultra‐High Sensitivity in the Visible Spectral Range

A metamaterial-based plasmonic sensor composed of thin metal and polymer layers deposited on top of a highly ordered porous alumina exhibits a sensitivity of more than 4800 nm per refractive index unit in the visible spectral range. The device is robust, cheap, has a large functional area of about 2 cm2, and the overall transmission is tunable by varying the film thickness.

Surface plasmon resonance of nanoshell particles with PMMA-graphene core

Purpose – The purpose of this paper is to contribute an analytical and numerical study of a new type of nanoshell particles operating in the visible regime. Design/methodology/approach – The structure consists of a core/shell particle, arranged in a planar array configuration, with a polymethyl methacrylate (PMMA)-graphene core and gold thin shell. Findings – By exploiting the proposed analytical model the design of a metamaterial-based sensor, operating in the optical frequency range, for the detection of tissue diseases is shown. Originality/value – Full-wave simulations confirm the capability of the proposed sensor to identify different compounds by refractive index measurement.

Wireless measurement of elastic and plastic deformation by a metamaterial-based sensor.

We report remote strain and displacement measurement during elastic and plastic deformation using a metamaterial-based wireless and passive sensor. The sensor is made of a comb-like nested split ring resonator (NSRR) probe operating in the near-field of an antenna, which functions as both the transmitter and the receiver. The NSRR probe is fixed on a standard steel reinforcing bar (rebar), and its frequency response is monitored telemetrically by a network analyzer connected to the antenna across the whole stress-strain curve. This wireless measurement includes both the elastic and plastic region deformation together for the first time, where wired technologies, like strain gauges, typically fail to capture. The experiments are further repeated in the presence of a concrete block between the antenna and the probe, and it is shown that the sensing system is capable of functioning through the concrete. The comparison of the wireless sensor measurement with those undertaken using strain gauges and extensometers reveals that the sensor is able to measure both the average strain and the relative displacement on the rebar as a result of the applied force in a considerably accurate way. The performance of the sensor is tested for different types of misalignments that can possibly occur due to the acting force. These results indicate that the metamaterial-based sensor holds great promise for its accurate, robust and wireless measurement of the elastic and plastic deformation of a rebar, providing beneficial information for remote structural health monitoring and post-earthquake damage assessment.