Microwave Resonator Research Articles

Demonstration of highly sensitive wideband microwave sensing using ensemble nitrogen-vacancy centers

Microwave magnetometry is essential for the advancement of microwave technologies. We demonstrate a broadband microwave sensing protocol using the AC Zeeman effect with ensemble nitrogen-vacancy (NV) centers in diamond. A widefield microscope can visualize the frequency characteristics of the microwave resonator and the spatial distribution of off-resonant microwave amplitude. Furthermore, by combining this method with dynamical decoupling, we achieve the microwave amplitude sensitivity of 5.2 μT/Hz, which is 7.7 times better than 40.2 μT/Hz obtained using the protocol in previous research over a sensing volume of 2.77 μm×2.77 μm×30 nm. Our achievement is a concrete step in adapting ensemble NV centers for wideband and widefield microwave imaging.

Permittivity measurement of fluidics with high‐sensitivity by chandelier form microwave sensor

AbstractIn this manuscript, a microwave resonance sensor (MRS) was presented composed of interdigital structure, meander structure, chandelier‐form, and T‐shaped structure. The combination of four structures results in a good electromagnetic field strength at the sensing location. It caused increased sensitivity. Due to the high use of methanol in industry, samples have been selected from this material. The samples used are methanol and water solution and place on location sensing. For measurement was used samples with 80% methanol with a permittivity of 59%–10% methanol with a permittivity of 77. Also, tissue samples including sheep, chicken and fish have been used to measure the proposed sensor. The resonance frequency of the samples changes in the range of 2.14‐1.46 GHz. The sensitivity of the presented MRS is 2.6% and the Q‐factor is 1252.

Microwave resonance enhanced CO2 reduction using biochar

Microwave resonance enhanced CO2 reduction using biochar

A PDMS-Assisted Back-to-Back SIW Re-Entrant Cavity Microwave Resonator Film for VOC Gas Detection

A PDMS-Assisted Back-to-Back SIW Re-Entrant Cavity Microwave Resonator Film for VOC Gas Detection

Piezoelectric loss of superconducting microwave resonators integrated with thin-film lithium niobate

Piezoelectric loss of superconducting microwave resonators integrated with thin-film lithium niobate

Recent advances in TiO2 nanotube layers – A mini review of the latest developments in nanotube preparation and applications in photocatalysis and microwave sensing

AbstractSelf‐organized anodic TiO2 nanotube (TNT) layers prepared by anodization of Ti substrates have attracted great interest within the last 20 years, due to their unique properties and low‐cost synthesis. This mini review article aims to shortly summarize the most recent developments in the TNT layer synthesis and applications. It presents the synthesis of high aspect ratio (HAR) TNT layers in a short time by accelerating the TNT layer growth rates in lactic acid containing electrolytes. Furthermore, the etching of TNT layers towards TNT bundles of homogeneous size and single tube powders is discussed, as well as the possibility to grow TNT layers on non‐planar Ti substrates, which cannot be directly connected to the potentiostat (e.g., Ti spheres or 3D Ti meshes). As a relatively new application, the employment of TNT layers in microwave resonator sensors is introduced. Last, but not least, approaches of upscaling the TNT layer size from the laboratory scale towards significantly larger scale are outlined and reviewed.

Mg Ion Plasma Generated by a High Magnetic Field in a Microwave Resonator

The generation and reduction reaction of magnesium plasma were studied using a cylindrical transverse magnetic-mode applicator in magnetic and electric field modes. By heating Mg powder using the magnetic field mode, plasma was generated with the evaporation of Mg and stably sustained. When the Mg plasma sample was introduced into the reaction zone and exposed to microwave and lamp heating, a reduction reaction of scandium oxide also occurred. The results of this study provide prospects for the development of a larger microwave refining system.

Magnetic and intrinsic dielectric properties of multiferroic GdFe1-xNixO3 (0.0 ≤ x ≤ 0.2) perovskites

Rare-earth transition-metal oxides with a perovskite crystal structure are at the forefront of the quest for new multifunctional materials, focusing on rare-earth orthoferrites ReFeO3. GdFeO3 is a multiferroic material that exhibits antiferromagnetic behavior, weak ferromagnetism, and ferroelectricity. The multiferroism of GdFeO3 can be tailored by substituting Fe with Ni. Recently, it was reported that the polycrystalline GdFe1-xNixO3 (x = 0, 0.1, 0.2) samples are materials with high dielectric constant at radio frequencies and room temperature, showing an increase in dielectric constant by introducing Ni3+ ions at Fe sites and reaching values in the order of ε'∼103 to 104, enabling their application as capacitors and miniaturized microwave resonators. In this paper, we examined the impact of Ni-substitution on the magnetic and intrinsic dielectric properties of GdFeO3 perovskite by analyzing the active-polar phonons through infrared reflectance spectroscopy and showed that its high dielectric constant has an extrinsic origin.

Impact of Imaging Biomarkers and AI on Breast Cancer Management: A Brief Review.

Breast cancer stands out as the most frequently identified malignancy, ranking as the fifth leading cause of global cancer-related deaths. The American College of Radiology (ACR) introduced the Breast Imaging Reporting and Data System (BI-RADS) as a standard terminology facilitating communication between radiologists and clinicians; however, an update is now imperative to encompass the latest imaging modalities developed subsequent to the 5th edition of BI-RADS. Within this review article, we provide a concise history of BI-RADS, delve into advanced mammography techniques, ultrasonography (US), magnetic resonance imaging (MRI), PET/CT images, and microwave breast imaging, and subsequently furnish comprehensive, updated insights into Molecular Breast Imaging (MBI), diagnostic imaging biomarkers, and the assessment of treatment responses. This endeavor aims to enhance radiologists' proficiency in catering to the personalized needs of breast cancer patients. Lastly, we explore the augmented benefits of artificial intelligence (AI), machine learning (ML), and deep learning (DL) applications in segmenting, detecting, and diagnosing breast cancer, as well as the early prediction of the response of tumors to neoadjuvant chemotherapy (NAC). By assimilating state-of-the-art computer algorithms capable of deciphering intricate imaging data and aiding radiologists in rendering precise and effective diagnoses, AI has profoundly revolutionized the landscape of breast cancer radiology. Its vast potential holds the promise of bolstering radiologists' capabilities and ameliorating patient outcomes in the realm of breast cancer management.

Design of novel highly sensitive sensors for crack detection in metal surfaces: theoretical foundation and experimental validation

The application of different types of microwave resonators for sensing cracks in metallic structures has been subject of many studies. While most studies have been focused on improving the sensitivity of planar crack sensors, the theoretical foundation of the topic has not been treated in much detail. The major objective of this study is to perform an exhaustive study of the principles and theoretical foundations for crack sensing based on planar microwave resonators, especially defective ground structures (DGS) including complementary split ring resonators (CSRRs). The analysis is carried out from the equivalent circuit model as well as the electromagnetic (EM) field perspectives, and guidelines for the design of crack sensors with high sensitivity are developed. Numerical and experimental validation of the provided theoretical analysis is another aim of this article. With this aim, the developed guidelines are used to design a crack sensor based on a single-ring CSRR. It is shown that the sensitivity of the proposed sensor is almost three times higher than the sensitivity of a conventional double-ring CSRR. Moreover, it is demonstrated that folded dumbbell-shape DGS resonators can be used to achieve even higher sensitivities. The CSRR-based crack sensors presented in this study and other studies available in the literature are only sensitive to cracks with a specific orientation. To address this limitation, a modified version of the DGS is proposed to sense cracks with arbitrary orientations at the cost of lower sensitivity. The performance of all the presented sensors is validated through EM simulation, equivalent circuit model extraction, and measurement of the fabricated prototypes.

Cryogenic ion trap system for high-fidelity near-field microwave-driven quantum logic

We report the design, fabrication, and characterization of a cryogenic ion trap system for the implementation of quantum logic driven by near-field microwaves. The trap incorporates an on-chip microwave resonator with an electrode geometry designed to null the microwave field component that couples directly to the qubit, while giving a large field gradient for driving entangling logic gates. We map the microwave field using a single 43Ca+ ion, and measure the ion trapping lifetime and motional mode heating rates for one and two ions.

Equivalent circuit of a planar microwave liquid sensor based on metamaterial complementary split ring resonator

Abstract In the present work, a study of a metamaterial complementary split ring resonator (CSRR) microwave planar sensor for dielectric liquid characterization is carried out using HFSS software. The design consists in a CSRR-loaded two ports rectangular patch microstrip-fed grounded planar structure. The investigated liquid sample is put in a capillary glass tube lying parallel to the surface of the sensor. The liquid test tube is deposited horizontally parallel to the surface of the planar sensor. The advantage of the design lies on the fact that it allows different orientations and multiple size possibilities of the test tube. This makes it possible to explore different resonant frequencies in the 2.1 GHz frequency band. Moreover, an optimization study is carried out to achieve a high sensitivity and a high-quality factor of the proposed sensor. To better understand the operation and to further verify the feasibility of the equivalent circuit, a parallel RLC resonant circuit is used to obtain the desired Z parameter responses Z 11, Z 22, Z 21. A T-shaped electrical model of the proposed sensing structure is established using Advanced Design System (ADS) software. This latter constitutes one of the principal novelties of this work, which has never been addressed so far.

On-body non-invasive glucose monitoring sensor based on high figure of merit (FoM) surface plasmonic microwave resonator

High-figure of merit (FoM) plasmonic microwave resonator is researched as a non-invasive on-body sensor to monitor the human body's blood glucose variation rate in adults for biomedical applications, e.g., diabetic patients. The resonance frequencies of the proposed sensor are measured to be around {f}_{01}=3.25 GHz and {f}_{01}=4.67 GHz over the frequency band of DC to 6GHz which are suitable for monitoring interstitial fluid (ISF) changing rate. The 40times 40 {mathrm{mm}}^{2} sensor is experimentally wrapped on the human body arm to monitor the blood glucose changing rate via amplitude and frequency variations of the sensor. Amplitude variation and frequency shift are measured to be around 7 dB and 30 MHz, respectively. The measured results demonstrate the high precision of the proposed approach to depict a valid diagram for glucose changing rate due to good impedance matching of the designed microwave sensor and human body. The sensor is shown to enhance the sensitivity by a factor of 5 compared to the conventional ones.

Permittivity-Based Microparticle Classification by the Integration of Impedance Cytometry and Microwave Resonators.

Permittivity of microscopic particles can be used as a classification parameter for applications in materials and environmental sciences. However, directly measuring the permittivity of individual microparticles has proven to be challenging due to the convoluting effect of particle size on capacitive signals. To overcome this challenge, we built a sensing platform to independently obtain both the geometric and electric size of a particle, by combining impedance cytometry and microwave resonant sensing in a microfluidic chip. This way the microwave signal, which contains both permittivity and size effects, can be normalized by the size information provided by impedance cytometry to yield an intensive parameter that depends only on permittivity. The technique allowed us to differentiate between polystyrene and soda lime glass microparticles -below 22 microns in diameter- with more than 94% accuracy, despite their similar sizes and electrical characteristics. Furthermore, we show that the same technique can be used to differentiate between normal healthy cells and fixed cells of the same geometric size. The technique offers a potential route for targeted applications such as environmental monitoring of microplastic pollution or quality control in pharmaceutical industry. This article is protected by copyright. All rights reserved.

Coupling-Based Sensing With a Microwave Resonator for Single Nanoscale Particles Detection

Coupling-Based Sensing With a Microwave Resonator for Single Nanoscale Particles Detection

Structural and functional assessment of the condition of wound bed using microwave dielectrometry and laser doppler flowmetry

The aim of the work was to develop and test a combined method for assessing the structural and functional features of the burn wound and periwound area with the use of microwave dielectrometry and Dopplerometry. The study was performed on twenty Wistar rats, thermal injuries from contact were created on each rat, and ten healthy animals. The assessment of the wound condition was performed 24 and 72 hours after burn injury. The study of the dielectric properties of tissues was carried out using a hardware and software complex for near-field resonant microwave sensing. From the results of our studies, it can be concluded that in the early post-injury period (within the first days), a sharp coordinated decrease in the intensity of microcirculation and dielectric permittivity is observed in the wound tissues, gradually and partially restored by the end of the third day after burning. The increased microcirculatory blood flow to the periwound area, leading to an increase in the degree of tissue hydration was observed, and as a consequence, the values of these two indices became higher. In addition, it has been shown that during thermal trauma, a regulatory imbalance of factors providing capillary blood flow around a burn wound area and surrounding tissues is formed, which is compensatory in nature and, in the absence of adequate correction, contributes to the inhibition of regeneration processes. Thus, the combination of the methods used in this study may potentially provide more specific information for a description of the structural and functional features of the analyzed tissue and their dynamics. This is clearly shown by the example of an experimental burn wound.

Maser threshold characterization by resonator Q-factor tuning

Whereas the laser is nowadays an ubiquitous technology, applications for its microwave analog, the maser, remain highly specialized, despite the excellent low-noise microwave amplification properties. The widespread application of masers is typically limited by the need of cryogenic temperatures. The recent realization of a continuous-wave room-temperature maser, using NV− centers in diamond, is a first step towards establishing the maser as a potential platform for microwave research and development, yet its design is far from optimal. Here, we design and construct an optimized setup able to characterize the operating space of a maser using NV− centers. We focus on the interplay of two key parameters for emission of microwave photons: the quality factor of the microwave resonator and the degree of spin level-inversion. We characterize the performance of the maser as a function of these two parameters, identifying the parameter space of operation and highlighting the requirements for maximal continuous microwave emission.

Microwave resonant device for water content on-line measurement of lubricating oil

An on-line measurement device of water content in lubricating oil based on microwave resonance technology is presented. By utilizing finite-element analysis and high-frequency structure simulator software HFSS, a semi-hermetic resonator (22 mm in diameter and 25 mm in length) for this device is designed, and the measurement results are simulated. In the experiment, the resonance frequency is chosen as the measurement parameter, in which the frequency band is 9.302 ∼ 9.307 GHz. In the water content range of 0 to 500 ppm (by volume), the resonance frequency decreases linearly with increasing water content, which is consistent with the simulation. The sensitivity is 1 MHz per 100 ppm of water content, and the maximum error in water content is 33 ppm. With temperature compensation in the range of 15 °C to 25 °C, the measurement resolution of this device is better than 100 ppm.

Characterization of superconducting through-silicon vias as capacitive elements in quantum circuits

The large physical size of superconducting qubits and their associated on-chip control structures presents a practical challenge toward building a large-scale quantum computer. In particular, transmons require a high-quality-factor shunting capacitance that is typically achieved by using a large coplanar capacitor. Other components, such as superconducting microwave resonators used for qubit state readout, are typically constructed from coplanar waveguides, which are millimeters in length. Here, we use compact superconducting through-silicon vias to realize lumped-element capacitors in both qubits and readout resonators to significantly reduce the on-chip footprint of both of these circuit elements. We measure two types of devices to show that through-silicon vias are of sufficient quality to be used as capacitive circuit elements and provide a significant reduction in size over existing approaches.

Detection of persistent current correlation in cavity-QED

We simulated the radiative response of a cavity quantum electrodynamics (QED) inductively coupled to the ring pierced by magnetic flux and analyzed its spectral dependence to get insight into persistent current dynamics. Current fluctuations in the ring induce changes in the microwave resonator: shifting the resonant frequency and changing its damping. We use the linear response theory and calculate the current response function by means of the Green function technique. Our model contains two quantum dots which divide the ring into two arms with different electron transfers. There are two opposite (symmetric and asymmetric) components of the persistent current, which interplay can be observed the response functions. The resonator reflectance shows characteristic shifts in the dispersive regime and avoided crossings at the resonance points. The magnitude of the resonator frequency shift is greater for coupling to the arm with higher transparency. Fluctuations of the symmetric component of the persistent current are relevant for a wide range of the Aharonov–Bohm phase ϕ, while the asymmetric component becomes dominant close to ϕ≈π (when the total persistent current changes its orientation).