High Quality Factor Value Research Articles

Microwave properties of SrY2O4 spinel synthesized for advanced applications

This study investigated the microwave dielectric properties and microstructures of SrY2O4 ceramics fabricated using the conventional solid-state route. The investigation revealed that the dielectric constant (ε r ) values exhibited saturation behavior, reaching a plateau within the range of 14–15. Notably, high quality factor (Q⋅f) values ranging from 64,500 to 92,000 (measured at 11 GHz) were achievable when sintering temperatures were maintained between 1480 and 1520 °C. Furthermore, the temperature coefficient of resonant frequency (τ f ) demonstrated minimal sensitivity to variations in sintering temperature. Significantly, SrY2O4 ceramics sintered at 1520 °C for 4 h exhibited a desirable combination of microwave dielectric properties, including a high ε r value of 15, an exceptional Q⋅f value of 92,000, and a favorable τ f value of −6.2 ppm/°C. These findings suggest the potential of SrY2O4 ceramics, particularly under these specific sintering conditions, for applications in microwave devices.

Design of a 1D PhC biosensor with enhanced sensitivity based on useful features provided for the detection of waterborne bacteria

In this article, we propose a one-dimensional photonic crystal (1D-PhC) biosensor design to detect water-borne bacteria such as Shigella, Vibrio cholera, Salmonella, and E. coli. The theoretical reflectance spectrum of a 1D-PhC and the sensitivity of types of bacteria such as Shigella flexneri, Salmonella, E. coli, and Vibrios cholera are investigated by using the transfer matrix method and MATLAB software. The impact of incident angle and central wavelength on the performance and sensitivity of biosensors are studied. The suggested sensor's sensing process is dependent on variations in the refractive indices of different species of bacteria. The variation in the central wavelength, angle of incidence, the sensitivity of the proposed structure, and other parameters such as full width at half maximum, quality factor, damping ratio, and detection limit can be enhanced. The obtained average sensitivity of our design has a value of 4073 nm/RIU at optimum conditions of defect layer thickness and incident angle. Also, the proposed biosensor design exhibits a high quality factor value of 10996.2165 and a low detection limit value of 0.44607×10-5\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.44607 \ imes \\,10^{ - 5}$$\\end{document} RIU.

Voltage-controlled oscillators using CFOAs with correction terminal Z

ABSTRACT In this work, a realization of a voltage-controlled LC oscillator (VCO), using monolithic current-feedback operational amplifiers (CFOAs) with accessible correction terminal Z, is proposed. The frequency variation for the developed oscillator is obtained by replacing the capacitor in the resonant LC circuit with pairs of varactor diodes that use a common cathode. The barrier capacitance of the varactor diodes is controlled by a DC voltage obtained from an external voltage source. The proposed circuit configurations include single active element, a small number of discrete components, an operating frequency range of up to about 10 MHz and a relatively high value of the equivalent quality factor. To verify the effectiveness of the realised oscillators, results of computer simulations and experimental studies of sample electronic circuits using commercially available monolithic CFOAs with correction terminal Z are presented. Moreover, the obtained experimental results confirm the theoretical analyses of the circuits and the obtained mathematical expressions for the basic parameters, and the differences between them are within 10% and are mainly due to tolerances in the technological parameters of the used electronic components.

Incident angle dependent tunable multiband infrared absorption based sensor

The effect of electromagnetic (EM) resonance in the graphene resonator and multiple reflections taking place in the dielectric spacer can provide the multiband infrared absorption. The intensity of resonance spectrum occurring due to the formation of EM dipoles in resonator can be controlled by patterning it using desired perturbation. The absorber response can be set with the multiple narrow and broad absorption peaks together by modulating the electrical properties of graphene material. The proposed absorber provides the incident angle dependent behavior with linear variation in the resonant wavelengths by maintaining the high absorption. This can provide a new way of tuning the antenna response by angle of incidence. The implemented absorber can provide the triple narrow bands which can be utilized for performing the refractive index sensing. The proposed absorber provides a significant value of sensing performance parameters including sensitivity, full-width-half-maxima, and figure-of-merit with the high value of quality factor. Moreover, the proposed absorber offers the ability of generating an extra narrow absorption band in the case of presence of sensing analyte of specific thickness and refractive index range making it highly sensitive for the detection of specific surroundings including the bio-cells, chemicals and humidity in the air. The broadband characteristics of the proposer absorber can be utilized in implementing the infrared EM shields and thermal storage components.

Ultrathin, Ultra Narrow Band DMMA for Biosensing Applications.

A new ultrathin, ultra narrow band Dielectric based Metamaterial Absorber (DMMA) is designed for biosensing applications. The absorber provides dual-band response with perfect absorption with ultra-narrowband absorption characteristics with resonances at 5.98 THz and 6.72 THz. The absorber consists of a silicon based square split ring (SSSR) along with a graphene based circular split ring (GCSR) for the generation of perfect and ultra-narrow absorption characteristics. By varying the chemical potential of the graphene, the tunability and controllability is achieved for the proposed absorber. Due to its ultra narrow band absorption characteristics, the proposed absorber can be used for sensing cancer in various parts of the body, malaria, glucose in water and other chemicals. The unique features of the proposed absorber are its ultra-thin structure, simple design, tunability, polarization insensitivity, ultra narrow absorption bandwidth, high sensitivity, high Figure of Merit (FOM), and very high Quality factor (Q) values in a single device for detecting different diseases and chemicals.

Flexible microwave sensor films based on nested-complementary split ring resonator for liquid dielectric constant detection

This paper proposes a flexible double-sided attached microwave sensor film for real-time measurement of the liquid dielectric constant, and proposes a nested-complementary split ring resonator（NCSRR）structure with high sensitivity and quality factor values that is based on the structure evolution of a complementary split ring resonator（CSRR）. The sensor films are composed of a ground film with an NCSRR structure and a U-shaped microstrip line film. By taking a borosilicate glass beaker and a polypropylene beaker as examples, two types of microwave sensors are formed by attaching films to both sides of the beakers. Lubricating oil with 0%− 25% water content is added to the beakers separately, and the dielectric constants of the mixture are characterized nondestructively by the transmission coefficient (S21) of the device. According to the mathematical model established from the measurement results, the resonant frequencies of both sensors are linearly and negatively correlated with the dielectric constant of the liquid to be measured, which proves that the sensor film can be attached to a substrate with arbitrary curvature to form a microwave resonant sensor.

Novel temperature stable (Na0.5Y0.5)MoO4 microwave dielectric ceramics with TiO2 addition

Novel scheelite-structured (Na0.5Y0.5)MoO4 ceramic materials featuring high quality factor (Q׃) values (>80000 GHz) were sintered at the temperatures ranging from 900 to 1100 °C. The sintering characteristics, crystalline structure, and microwave dielectric properties of the (Na0.5Y0.5)MoO4 ceramic samples were investigated systematically. The optimal properties of εr = 11.5, Q׃ =88673 GHz, and τf = -56.49 ppm/°C were achieved in the specimen sintered at 1050 °C. Moreover, TiO2 was employed to modify the large negative temperature coefficient of resonance frequency (τf) of (Na0.5Y0.5)MoO4. In the ceramic samples of 1-x(Na0.5Y0.5)MoO4-xTiO2, a near-zero τf of 0.68 ppm/°C with εr = 15.2 and Q׃=49047 GHz was achieved at x = 0.25 sintered at 975 °C.

Enhancement of Thermoelectric Performance for CuCl Doped P-Type Cu2Sn0.7Co0.3S3

Cu2SnS3 (CSS) has gained great attraction due to its constitutive earth-abundant elements and intrinsic low lattice thermal conductivity, κl, potentially providing high quality factor, B, and high zT value. However, the lack of band convergence is the bottleneck to enhancing the thermoelectric performance of Cu2SnS3 when performing the band engineering. To study the doping effect on the band structure and the thermoelectric performance, the composite Cu2Sn0.7Co0.3S3-xCuCl (x = 0, 0.1, 0.2, 0.3) (CSCS-xCuCl) has been investigated for the first time. The samples showed excellent data repeatability at high temperatures of up to 700 K. It was found that CuCl could compensate the Cu loss, enhance the phonon scattering and minimize the adverse effect on the power factor, PF. The ultralow lattice thermal conductivity could reach 0.38 W m-1 K-1 for the nominal composition of CSCS-0.3CuCl at 700 K. A peak zT of 0.56 (evaluated with no cold finger effect) was realized at 700 K when x = 0.3, which is almost double the performance of pristine samples.

All optical comparator using tera hertz optical asymmetric demultiplexer (TOAD)

TOAD or Tera Hertz Optical Asymmetric Demultiplexer is an optical switch. Using this switch, we have invented an optical comparator. This optical comparator circuit is very simple in structure with a higher speed (200 Gbps) and finds useful application in optical computation and communication network system. We have simulated all three outputs in detail and shown the eye diagram of all three outputs of the optical comparator. We found high values of extinction ratio (ER), contrast ratio (CR), and quality factor (Q value) for the three outputs of the comparator.

A Novel Method for Carbendazim High-Sensitivity Detection Based on the Combination of Metamaterial Sensor and Machine Learning.

Benzimidazole fungicide residue in food products poses a risk to consumer health. Due to its localized electric-field enhancement and high-quality factor value, the metamaterial sensor is appropriate for applications regarding food safety detection. However, the previous detection method based on the metamaterial sensor only considered the resonance dip shift. It neglected other information contained in the spectrum. In this study, we proposed a method for highly sensitive detection of benzimidazole fungicide using a combination of a metamaterial sensor and mean shift machine learning method. The unit cell of the metamaterial sensor contained a cut wire and two split-ring resonances. Mean shift, an unsupervised machine learning method, was employed to analyze the THz spectrum. The experiment results show that our proposed method could detect carbendazim concentrations as low as 0.5 mg/L. The detection sensitivity was enhanced 200 times compared to that achieved using the metamaterial sensor only. Our present work demonstrates a potential application of combining a metamaterial sensor and mean shift in benzimidazole fungicide residue detection.

Low-Cost Microwave Sensor for Characterization and Adulteration Detection in Edible Oil

A low-cost microwave sensor was designed for oil adulteration detection and characterization of pure edible oil using dielectric spectroscopy. The sensor’s final design was fabricated on a low cost 1.6 mm thick FR-4 substrate with a combination of a complementary split ring resonator and a transmission line. The sensor’s dimensions were 35 × 30 × 1.6 mm3 with a substrate dielectric constant of 4.3. A 5.25 GHz resonance frequency was selected as a reference for characterization and adulteration detection in pure edible oil. Initially, pure olive, caster, flaxseed, and mustard oil were characterized by the design sensors, with frequency shifts of 250, 370, 150, and 320 MHz, respectively. Pure olive oil with adulteration of castor, mustard, and argemone oil, was tested by placing the samples directly on the sensor. The experimental results showed that the sensor can detect 10% to 30% adulteration in the olive oil. The maximum sensitivity, frequency shift and quality factor were noted as 4.6, 530 MHz and 39, respectively. The high values of sensitivity and quality factor, along with agreement between simulated and experimental results, makes our sensor a good candidate for oil characterization and adulteration detection.

Chitosan nanofibres and polypropylene meltblown substrate based multilayer respiratory filter for byssinosis prevention

Byssinosis is a chronic obstructive pulmonary disease very common in textile cotton workers due to inhalation of fine cotton dust and gram negative bacteria. A three layer composite respiratory filter was developed for Byssinosis prevention by using the combination of polypropylene (PP) based meltblown layers and chitosan nanofibres (CSNF). Filtration efficiency against fine particulates ranges from 100 nm to 2.5 μm and anti-bacterial activity against Pantoea agglomerans were investigated. Chitosan nanofibres were produced by using the electrospinning process and were sandwiched between two PP layers to improve the overall surface area of the filter as well as providing a protective barrier against bacterial pathogens. The filter sample with just 2 hour’s CSNF coating showed more than 99% filtration efficiency with a low pressure drop of 71.6 Pa and a high quality factor value 0.082. The antibacterial performance of CSNF layers achieved up to 91% against the Pantoea agglomerans. Finally, results concluded that the developed respiratory filter can potentially reduce Byssinosis in textile workers.

Generating multiple resonances in ultrathin silicon for highly selective THz biosensing

A technique is implemented for achieving the multiband terahertz (THz) absorption with high-quality factor in an absorber containing an ultrathin silicon resonator. The symmetrical perturbation is done in the silicon layer for obtaining the multiple multi-order electric and magnetic resonances. The proposed absorber structure provides the polarization insensitive absorption spectrum with ten absorption peaks out of which seven remain with the level of more than 90%. The ultranarrow absorption spectrum can be utilized in THz biosensing applications specially for the detection of breast cancer, malaria in blood and glucose in water. It offers highest sensitivity as 0.416 THz/thickness unit (TU) and 1.02 THz/refractive index unit (RIU) during analyte thickness and refractive index sensing, respectively. The proposed absorber can provide the high value of quality factor along with all other improved parameters like sensitivity and figure of merit. Moreover, graphene nano-rings can also be utilized for obtaining the controllability in the frequency response of the absorber.

Solid Characterization Utilizing Planar Microwave Resonator Sensor

This paper outlines the design and the implementation of a planar microwave resonator sensor for sensing application using the perturbation concept in which the dielectric characteristics of the resonator influence the quality factor (QF) and the resonance frequency. The designed sensor is fabricated using Roger 5880, and it is operating at 2.27 GHz in ranges of 1-3 GHz for testing solid materials. In addition, applying a specific experimental methodology, practical material is used as material samples such as those in Roger 5880, Roger 4350, and FR4. To investigate the microwave resonator sensor performance, an equivalent circuit model (ECM) is introduced. The proposed sensor has achieved a narrow bandwidth and high QF value of 240 at an operating frequency of 2.27GHz. Besides, the sensitivity and accuracy of the sensor is more than 80%, which makes this sensor an excellent solution to characterize the material, especially in discovering the material characteristics and quality.

Analysis and Optimization of Acoustic Sensor Based on Fiber Fabry-Pérot Etalon

Fiber optic sensors have been extensively studied in recent years. Due to the advantages of high sensitivity, compact structure, and anti-electromagnetic interference, the sensors based on the Fabry-Pérot (FP) cavity have become a research hotspot. The Fabry-Pérot etalon (FPE) acoustic sensor consists of two Plano-Concave Lenses coated with a highly reflective film, the Graded Index Lenses (GRIN) lenses, the optical fibers and a glass tube. Acoustic detection is realized by detecting the small change in the refractive index of the cavity medium caused by sound pressure, and the phase modulation technology realizes the modulation and demodulation of the acoustic signal. Matlab is used to analyze the influence of refractive index changes on the resonance spectrum and sensitivity curve, so the cavity mirrors with the reflectivity of 99% are selected. The structure of the FPE sensor is optimized using Zemax software. The optimal length of the sensor is 29.973 mm and the diameter is 6 mm. The high quality factor values of experiment and simulation are both 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> . At the same time, the experimental results show that the sensor has a response in the range of 50 Hz-20 kHz, with a high Signal-to-Noise Ratio (SNR) of 61.97 dB when the sound pressure is 19.795 Pa, and the sensitivity response is linear, reaching 0.19013 V/Pa. The research results provide useful guidance for the optimal design of the sensor, and the correctness of the theory is verified by the performance test of the optical acoustic sensor.

Analogue of electromagnetically induced transparency in square slotted silicon metasurfaces supporting bound states in the continuum.

In this work, a silicon metasurface designed to support electromagnetically induced transparency (EIT) based on quasi-bound states in the continuum (qBIC) is proposed and theoretically demonstrated in the near-infrared spectrum. The metasurface consists of a periodic array of square slot rings etched in a silicon layer. The interruption of the slot rings by a silicon bridge breaks the symmetry of the structure producing qBIC stemming from symmetry-protected states, as rigorously demonstrated by a group theory analysis. One of the qBIC is found to behave as a resonance-trapped mode in the perturbed metasurface, which obtains very high quality factor values at certain dimensions of the silicon bridge. Thanks to the interaction of the sharp qBIC resonances with a broadband bright background mode, sharp high-transmittance peaks are observed within a low-transmittance spectral window, thus producing a photonic analogue of EIT. Moreover, the resonator possesses a simple bulk geometry with channels that facilitate the use in biosensing. The sensitivity of the resonant qBIC on the refractive index of the surrounding material is calculated in the context of refractometric sensing. The sharp EIT-effect of the proposed metasurface, along with the associated strong energy confinement may find direct use in emerging applications based on strong light-matter interactions, such as non-linear devices, lasing, biological sensors, optical trapping, and optical communications.

Narrower Band Matching With Low Quality Factor Values

In this brief, a new approach based on quality factor technique is proposed to design narrower band matching networks. The main idea is to use one series and one parallel lossless one-port LC network between generator and load resistances. In the proposed approach, it is not necessary to use a high quality factor value to get narrower band, it is enough to use the quality factor value defined by generator and load resistances. After explaining the rationale of the new approach, an example is given to compare the performances of the proposed and existing methods in the literature.

Ultra-narrow-band terahertz perfect metamaterial absorber for refractive index sensing application

We numerically propose and demonstrate an ultra-narrow perfect metamaterial absorber (PMA) for refractive index sensing applications in the terahertz region. The designed PMA is only composed of a gallium arsenide (GaAs) cross-shaped resonator array on an opaque copper/silicon substrate. Simulated results show that the proposed PMA can achieve a near-perfect absorption peak with an absorptivity of 99.49% and a high quality factor value of 637 at 2.44THz. The physical mechanism of the narrow absorption is explained by the electric field, magnetic field and Poynting vector distributions. As a refractive index sensor, its sensitivity and figure of merit reach up to 1.94THz/refractive index unit (RIU) and 506RIU−1, respectively. These results make the proposed PMA to have great potential in detecting, imaging and sensing applications.

Ultralow Surface Resistance via Vacuum Heat Treatment of Superconducting Radio-Frequency Cavities

We report on an effort to improve the performance of superconducting radiofrequency cavities by the use of heat treatment in a temperature range sufficient to dissociate the natural surface oxide. We find that the residual resistance is significantly decreased, and we find an unexpected reduction in the BCS resistance. Together these result in extremely high quality factor values at relatively large accelerating fields Eacc ~20 MV/m: Q0 of 3-4x10^11 at <1.5 K and Q0 ~5x10^10 at 2.0 K. In one cavity, measurements of surface resistance versus temperature showed an extremely small residual resistance of just 0.63+/-0.06 nOhms at 16 MV/m. SIMS measurements confirm that the oxide was significantly dissociated, but they also show the presence of nitrogen after heat treatment. We also present studies of surface oxidation via exposure to air and to water, as well as the effects of very light surface removal via HF rinse. The possibilities for applications and the planned future development are discussed.

Experiments With a Compact Wireless Power Transfer System Using Strongly Coupled Magnetic Resonance and Metamaterials

The technology for inductive wireless power transfer (IWPT) by using strongly coupled magnetic resonance has been applied successfully to supply energy to several applications such as biomedical implants, radio frequency identification systems, Internet-of-Things sensors, and battery chargers for personal devices. In order to attain high values of efficiency and reach, the technology requires the employment of coils with high values of quality factor. However, this feature can only be found by using large wire coils. A compact IWPT system composed of printed coils, which typically have low values of quality factor, is proposed in this paper. An evolutionary algorithm is used to optimize the printed coil geometry so that it presents the greatest value of quality factor possible, according to the imposed restrictions. With the aim to improve the system efficiency and reach, the effect of metamaterial surfaces inclusion is investigated. In addition, in order to increase the amount of power processed by the system, a low-cost self-oscillating electronic converter is proposed to power it.