Resonant Research Articles

Leaf-Shaped Nanostrip Fed Graphene Plasmonic Nano-Antenna for Optical Near-Field Applications

The manuscript investigates the leaf-shaped nanostrip-fed graphene plasmonic nanopatch on a silicon dioxide surface for optical near-field applications. The dispersion properties of graphene and silicon dioxide are demonstrated through Drude and Lorentz modeling to examine the suitability of the materials for the plasmonic nano-antenna design. The nano-antenna parameters TSUB (substrate thickness), W (width of the nanostrip feed line) and RL(nano-antenna size) are adjusted to modify the plasmonic resonance frequency from 7.9 THz to 40.9 THz. The proposed leaf-shaped nanostrip-fed graphene plasmonic nanopatch exhibits a reflection of -43.27 dB at 36 THz with a gain of 8.19 dB at TSUB =125 nm, W = 40 nm and RL = 50 nm.

INVESTIGATION OF THE EFFECTS OF DIFFERENT FEED LINE STRUCTURES ON UWB ANTENNA PERFORMANCE BY CHARACTERISTIC MODE ANALYSIS

This study investigates the effect of various feed topologies on the parameters of a novel ultra-wideband (UWB) antenna using characteristic mode analysis. The proposed design is guided by characteristic mode analysis, commencing with a basic square structure. Initially, a closed-form estimate of the resonance frequencies of the primary modes is provided for the square-shaped structure. Subsequently, the characteristic modes that resonate in the frequency spectrum are modified by introducing symmetrical square slots. To excite these modes and achieve a wideband antenna that encompasses the relevant spectrum, the geometry of the feeding line is altered and its effects are examined. The study incorporates two fundamental feed line geometries: tapered and traditional feed impedance lines. The proposed UWB antennas are fabricated and measured to validate their performance. According to the measurement results a wide impedance bandwidth of 147.82% at -10 dB reference ((0.9–6 GHz)) and stationary radiation patterns across the operating frequency band are obtained for the tapered feed line. The results demonstrate a significant advantage of the tapered feed line over the traditional impedance line. The results for the fabricated prototypes exhibit high similarity to the simulated results. The findings confirm the applicability of the mode analysis method.

Determination of Lactoferrin Using High-Frequency Piezoelectric Quartz Aptamer Biosensor Based on Molecular Bond Rupture

In this study, an aptamer biosensor for detecting lactoferrin (LF) was developed using piezoelectric quartz-induced bond rupture sensing technology. The thiol-modified aptamer I was immobilized on the gold electrode surface of the quartz crystal microbalance (QCM) through an Au-S bond to specifically bind LF. It was then combined with aptamer–magnetic beads to amplify the mass signal. The peak excitation voltage was 8 V at the resonance frequency for the 60 MHz gold-plated quartz crystal. When the molecular bond cracking process occurred, the aptamer–magnetic beads combined on the surface of the piezoelectric quartz were removed, which resulted in an increase in quartz crystal resonance frequency. Therefore, the specific detection of LF can be realized. Under optimized experimental conditions, the linear range for LF was 10–500 ng/mL, the detection limit (3σ) was 8.2 ng/mL, and the sample recoveries for actual milk powder samples ranged from 97.2% to 106.0%. Compared with conventional QCM sensing technology, the signal acquisition process of this sensing method is simple, fast, and easy to operate.

Fabrication and characterization of lead lanthanum zirconate titanate ceramic-based fully transparent piezoelectric loudspeakers for next-generation electronic devices

Transparency is a critical attribute of next-generation electronic devices; this ensures unobstructed visibility while maintaining device functionality. Traditional electromagnetic coils are opaque, and piezoelectric materials with high optical transparency, low power consumption, and rapid responses are required when preparing innovative transparent electronics. In this study, we developed lead lanthanum zirconate titanate (PLZT) ceramics with excellent transparency (PLZT S1 = 65 %, PLZT S2 = 42 % at 550 nm) and piezoelectric properties (PLZT S1 = 180 pC/N, PLZT S2 = 470 pC/N). An indium tin oxide (ITO)-coated PLZT ceramic (PLZT S2) was used to create a fully transparent transducer with a glass diaphragm. This delivered outstanding sound output, attaining 105 dB at the resonance frequency (5.6 kHz) at an input of only 5 Vpp. To demonstrate the versatility of PLZT in terms of transparent electronic applications, PLZT transducers were placed on a desiccator wall; this showcased their capacity to emit a warning sound without compromising visibility when gas leaked inside the desiccator. An ITO-coated PLZT disc was employed to fabricate a loudspeaker with a polyethylene terephthalate (PET) diaphragm; this produced sounds from 30 dB to 68 dB across the entire voice frequency spectrum (500 Hz–8 kHz) with an input of 10 Vpp. This loudspeaker meets the demands of next-generation transparent electronics; optical visibility and high-quality sound reproduction are assured without any compromise in terms of sound quality or visual transparency.

Neurospectral Computation for the Resonant Characteristics of an Equilateral Triangular Patch Antenna on Suspended Substrates

Modeling and design of an equilateral triangular patch antenna on suspended and single substrate are accomplished in this paper. The spectral domain approach is important due to its accuracy, but has a high computational cost. On the other hand, the Artificial Neural Networks (ANNs) have recently become a fast and flexible vehicle for modeling and designing microwave antennas. This paper introduces electromagnetic knowledge combined with ANNs to compute the resonant frequency of the fundamental and higher order modes and to eliminate the difficulties of handling the singularity points encountered in the numerical evaluation of integrals. The resonant frequency results obtained from the neural model are in very good agreement with the experimental and theoretical results available in the literature.

Monitoring of a Low-Order Even Radial Vibrational Circumferential Mode in a Round Hollow Cylinder

This paper presents a nondestructive testing method for assessing the structural integrity of cylindrical elements by monitoring a range of radial vibrational modes, with a specific emphasis on the so-called ovalling mode. The method involves exciting the cylinder with a single vibration source in the radial direction and measuring the response using two vibration sensors positioned diametrically on the cylinder's surface. The ovalling mode was extracted from the frequency response by adding the in-phase signals recorded by the sensors. Experiments conducted on a PVC pipe showed good agreement between the measured resonance frequency of the ovalling mode and its predicted value, calculated using the theory for thin cylindrical shells and Finite Element Method simulations. This research is an investigation into the potential and reliability of this nondestructive technique for detecting corrosion and strength-weakening defects in concrete building elements, steel pillars, and columns. The extent of the strength reduction can be determined by analyzing the change in the resonance frequency of the ovalling mode.

Effect of annealing on flexoelectricity in hafnium oxide (HfO2)

Flexoelectricity is universal in all dielectrics, effective at high temperatures, and a promising transduction technique for nanoelectromechanical systems (NEMS). However, as flexoelectricity is still in its early stages, many aspects require further investigation. Understanding how flexoelectricity depends on material parameters like crystallographic phase and how temperature might affect it is important for selecting and optimizing the right material for technological applications. This work studies the influence of high-temperature annealing (and the consequent crystallization) in the flexoelectricity of hafnium oxide (HfO2), a material with significant technological relevance. We measure the flexoelectric coefficient for amorphous (not annealed) and annealed (slightly crystalline) phases of HfO2, with samples annealed in nitrogen or oxygen atmospheres. Our results indicate that the amorphous phase of HfO2 exhibits the highest flexoelectric coefficient (105 ± 10 pC/m), while annealed samples show a significant decrease, with the lowest value in nitrogen-annealed samples (26 ± 4 pC/m). Samples annealed in an oxygen atmosphere improve flexoelectric properties (54 ± 6 pC/m) compared to those annealed in nitrogen. Using cross-sectional imaging, x-ray diffraction, resonance frequency characterization, and relative permittivity measurements, we find that annealing promotes crystallization into the tetragonal phase and increases internal stress within the HfO2 layer, while most other parameters remain constant. We attribute the differences in flexoelectricity from the annealed samples to the quantity of oxygen vacancies in hafnium oxide. These oxygen vacancies in hafnium oxide seem to negatively affect the flexoelectric coefficient. This finding can be applied to optimize materials to enhance their flexoelectric properties.

A novel horizontal self-tuning piezoelectric energy harvester based on a beam-slider system

Abstract With the rapid development of piezoelectric energy harvesting technologies, this approach is emerging as a promising power source for smart sensors. Despite this progress, a significant challenge remains in achieving a wider bandwidth while increasing the output power. In response to this challenge, this paper introduces a horizontal self-tuning beam-slider piezoelectric energy harvester (STBS-PEH). This innovative harvester employs a unilateral beam-slider mechanism to enable self-tuning of the energy harvesting by adjusting its resonant frequency to match the external excitation frequency. The electromechanical coupled dynamic model of this harvester has been established. Comprehensive simulations and experimental analysis have been conducted to demonstrate the wide bandwidth and high output power characteristics of the proposed harvester. Notably, the simulation results exhibit strong agreement with the experimental findings. The resonance response bandwidth of the STBS-PEH is particularly noteworthy, which is twice that of a conventional cantilever beam piezoelectric energy harvester. The root mean square (RMS) voltage and output power of the developed STBS-PEH can reach 23.54 V and 194.61 µW, respectively, at a frequency of 21 Hz, with an excitation amplitude of 0.5 g. These results demonstrate that the STBS-PEH is capable of powering low-power electronic devices in a broadband vibrational environment.

Experimental investigation on the effect of concentration on the resonance frequency of lipid coated ultrasonically excited microbubbles

This study presents an experimental investigation of the influence of MB concentration on the resonance frequency of lipid-coated microbubbles (MBs). Expanding on theoretical models and numerical simulations from previous research, this work experimentally investigates the effect of MB size on the rate of resonance frequency increase with concentration, a phenomenon observed across MBs with two different lipid compositions: propylene glycol (PG) and propylene glycol and glycerol (PGG). Employing a custom-designed ultrasound attenuation measurement setup, we measured the frequency-dependent attenuation of MBs, isolating MBs based on size to generate distinct monodisperse sub-populations for analysis. The resonance frequency of MBs was determined by identifying the attenuation peak in the broadband attenuation ultrasound attenuation measurements. Our experimental findings confirm that larger MBs (≈2.1μm) demonstrate a more significant shift in resonance frequency (≈ 5 MHz, ≈ 40%) as a function of MB concentration. In contrast, smaller MBs (≈1.3μm) show a minor shift in the resonant frequency (≈ 1.8MHz, ≈ 8%), underlining the importance of size in determining acoustic behavior compared to changes in the lipid shell properties. Additionally, we observed that resonance frequency increase with concentration reaching a saturation point at higher concentrations. This plateau occurs at higher concentrations for larger MBs (≈2.1μm), while smaller MBs (≈1.6μm and ≈1.3μm) reach this saturation point at lower concentrations. Furthermore, the study highlights the small effect of bubble-bubble interactions on the resonance frequency of MB populations, particularly at lower MB concentrations and for smaller MBs. This insight is important for applications utilizing MB clusters, such as contrast-enhanced ultrasound imaging and MB-mediated therapies. While both size and lipid shell composition influence resonance frequency, MB size has a more significant effect. In conclusion, our findings affirm the need to consider both MB size and concentration when utilizing MBs for clinical and industrial ultrasonic applications.

A Novel High Common‐Mode Suppression Balanced Bandpass Filter With Elliptical SIW Resonator

ABSTRACTA novel substrate integrated waveguide resonator, specifically an elliptical SIW resonator (ESIWR), is proposed in this research. Due to the incomplete symmetry of ESIWR, compared to circular SIW resonator (CSIWR), the natural resonance frequencies of the first degenerate modes TMC110 and TMS110 are different. Additionally, by incorporating C‐slotlines, the coupling between the two ESIWRs is enhanced. Moreover, transmission zeros are introduced through source‐load coupling to enhance frequency selectivity. Furthermore, the use of meandering technique reduces the resonant frequency and lowers the relative size λg by 12.1%. The simulation and measurement results are in good agreement, demonstrating the realization of three transmission zeros with out‐of‐band suppression levels of 56.5, 68.1, and 69.3 dB, respectively, indicating excellent out‐of‐band suppression performance. Additionally, the measured minimum common‐mode suppression within the passband exceeds 55.8 dB, metal perturbation columns loading desirable common‐mode suppression. Based on the simulation and measurement results, this novel filter is well‐suited for RF front‐end devices in complex electromagnetic environments.

Optimized fractional order resonant model of supercapacitors based in error dominant frequency mitigation

A fractional order model for supercapacitors and a method for obtaining its parameters were proposed based in the association between a simplified model of one integer order capacitor (RC) with a fractional order parallel RLC impedance. Like all parallel RLC impedances, the fractional order parallel RLC impedance has a resonance frequency, however its response depends substantially on the fractional order, making it an important parameter for fitting the model to experimental data. Through the analysis of experimental galvanostatic charge and discharge curve and the application of a heuristic optimization algorithm, the parameters of the proposed model were obtained, pursuing to remove the main frequency component of the error between the data and the RC simplified model. The results demonstrated that the model obtained actually minimized the dominant frequency of the error and also resulted in a decrease in components at other frequencies, highlighting the advantage of the fractional order applied in the RLC proposed model.

Simultaneous cooling of high-frequency difference resonators through voltage modulation and intracavity-squeezed light

We propose a scheme to achieve simultaneous cooling of the mechanical and radio-frequency resonators in a hybrid optoelectromechanical system. By introducing the voltage modulation switch and intracavity-squeezed light, the high-frequency difference resonators can be successfully cooled to their quantum ground states by eliminating cavity mode dissipation through precise phase and amplitude matching of the squeezed pump field and the cooling optical field. More significantly, ground-state cooling can be achieved even in the highly unresolved sideband regime, and the quantum backaction heating can be effectively suppressed, leading to a significant improvement in cooling performance. Our work provides an alternative approach for quantum coherent manipulation of multiple mechanical systems with different resonant frequencies.

Investigation of the performance of oil-free linear compressor with magnetic resonance spring for pulse tube cryocooler

This study proposes a new type of oil-free linear compressor with a magnetic resonance spring, which uses a magnetic resonance spring to provide restoring force and adopts gas-lubricated bearings to provide support force for the piston. The frequency characteristics of the compressor, including magnetic spring stiffness, gas spring stiffness, and resonance frequency, are studied through experiments and theoretical analysis. The magnetic spring stiffness is 31403.31 N/m of the design compressor. Hooke’s law and Fourier decomposition are employed for the gas spring stiffness measuring the compression pressure gauged. Meanwhile, the gas spring stiffness is also obtained from the amplitude-frequency characteristic of the compressor by the back stepping technique with an electric parameter frequency scan. The experimental results demonstrate that the three measurement methods have good consistency in measuring the gas spring stiffness. The equivalent gas spring stiffness measured using the three methods and theoretical model are 72600.92 N/m, 71275.84 N/m, 71967.15 N/m, and 71929.25 N/m at 3 MPa charged pressure measured respectively. In addition, the refrigeration performance of the pulse tube cryocooler driven by the compressor is tested and the lowest temperature obtained in the cold end is 46.3 K under different charge pressure. Furthermore, an optimal frequency exists that enhances the refrigeration performance of the pulse tube cryocooler, and this optimal frequency remains constant regardless of changes in the charge pressure.

Vibration characteristic, quality factor and sensitivity analysis of a resonant micro-gyroscope based on the blue-sideband parameter modulation

In this paper, we design a nonlinear resonant micro-gyroscope based on the blue-sideband parameter modulation (BSPM), and Coriolis force acts in the axial direction of the resonant beam in the form of a twice-frequency parameter excitation. Considering the geometrical nonlinearity of the micro-beam, the dynamic equations of the resonant beam are derived and discretized according to Hamilton principle and Galerkin method. The discretized equations are subjected to perturbation analysis by using the multi-scale method, and the quality factors of the resonant beams are calculated by the half-power bandwidth method. Moreover, the sensitivity of micro-gyroscope is characterized by the amplitude ratio changes before and after the bifurcation of the nonlinear resonant beam. We conducted a detailed study on the effects of Coriolis force dynamic input, and BSPM on the amplitude-frequency response of resonant beam and the sensitivity of micro-gyroscope. The results indicate that when Coriolis force acts on the resonant beam in the form of a twice-frequency parameter excitation, it not only causes the resonant frequency of the micro-beam to shift but also significantly increases the amplitude of the resonant beam. The addition of BSPM significantly improves the quality factor of the resonant beam and enhances the signal-to-noise ratio. Under nonlinear conditions, when the modulation voltage is sufficiently large, the amplitude-frequency response of resonant beam exhibits two unstable regions near the resonant frequency. Although BSPM reduces the amplitude ratio sensitivity, there is still a 60 times improvement over conventional frequency shift sensitivity. Furthermore, BSPM reduces the nonlinearity degree of the amplitude ratio sensitivity by 64%, which is important for the design and fabrication of high-sensitivity resonant micro-gyroscope.

Zonal flow instability induced by nonlinear inertial waves in a librating cylinder with sloping ends

This paper compares the nonlinear dynamics of two key types of motion observed in a rotating liquid-filled cavity subject to external forcing: an inertial wave attractor and resonant inertial oscillations (inertial modes). Experiments are performed with a cavity having a specific shape of a truncated circular cylinder delimited by plane-parallel end walls inclined with respect to the cylinder base. The cavity rotation axis coincides with the axis of the cylindrical surface. Libration-type forcing is introduced by harmonic modulation of the background rotation frequency. The sloping end walls break the axial symmetry of the liquid domain: the shape of the axial-radial cross sections varies from parallelogram to rectangle depending on the azimuthal angle. It is found that, regardless of the liquid response type (wave attractor or inertial modes), the transition from linear to nonlinear dynamics follows the scenario of triadic resonance instability. However, the time-averaged zonal flow responds differently to the primary wave instability. Inertial-mode instability generates a system of azimuthally periodic averaged vortices, whose frequency coincides with the subharmonic frequency of the triadic resonance. At high libration amplitudes, a low-frequency component appears in the azimuthal velocity spectrum, being associated with excitation of the retrograde system of vortices. The development of the weakly nonlinear regime of the wave attractor is accompanied by the instability of the viscous boundary layers—fine-scale pattern formation occurs close to the reflection zones of the attractor branches at the cylindrical sidewall. In the strongly nonlinear wave regime, coherent vortex structures are excited, performing azimuthal and radial drifts.

Power Transmission Technology Using Wireless Network

In this paper, we have presented the concept of wireless transmission i.e. power transmission without using any type of the electrical conductor and/or wires. We have presented an idea that is discussed here about how electrical energy can be transmitted as microwaves so that to reduce the transmission, allocation and other types of losses. Such technique is known as Microwave Power Transmission (MPT). We have also presented and correlated several aspects with the currently available Power transmission systems to the related history of wireless power transmission systems and also the related developmental changes. The basic design, merits and demerits, applications of Wireless Power Transmission are also discussed . The paper describes the various types of WPT technologies; Inductive Coupling, Magnetic Resonance and Radio Frequency (RF) technology. It also discusses the advantages and shortfalls of each type. An extensive survey of past works was discussed. Results from the research findings showed that distance and conversion efficiency were limiting factors in implementing wireless transfer technology

Dual-nozzle 3D printing of fiber composites for fabrication of compliant lever-type vibration isolators with wide stopband

This study proposes fiber-composite lever-type vibration isolators with a wide stopband around the antiresonance frequency. The proposed mechanisms were 3D-printed monolithic structures with compliant butterfly hinges that mimic an ideal pinned support for the lever. Continuous carbon fiber and short carbon fiber regions were combined to achieve a wide low-frequency stopband. A rigid link model was developed to derive analytical solutions for the resonance and antiresonance frequencies of the proposed mechanisms. Frequency response analysis and modal analysis were performed to examine designs for widening the stopband using the finite element method. The print path-dependent anisotropy of short fiber-reinforced plastic was reflected in the finite element model. A dual-nozzle fiber-composite 3D printer was used to fabricate the proposed lever-type mechanisms. The measured vibration transmissibilities of the 3D-printed samples showed a similar improvement of the stopband width to the numerical analysis results, demonstrating that suitable designs of continuous fiber placement and hinge shape widened the stopband.

Graphene based THz filter design using open-loop resonator for space applications

This paper introduces a graphene-based tunable terahertz bandpass filter with a dual-mode open-loop resonator, designed to operate at a resonant frequency of 6.35 THz. Leveraging a graphene layer between the conductor and dielectric layers, the filter enables the propagation of surface plasmons, allowing dynamic tunability essential for terahertz applications. Key advantages of this design include precise bandwidth control, achieved by manipulating the resonator's physical parameters, and adaptable center frequency tuning through variations in graphene's chemical potential, providing a tuning range of approximately 0.16 THz. These reconfigurable properties make the filter highly suitable for integration into terahertz space communication systems, where adaptability and high performance are critical. The proposed design's ability to fine-tune both bandwidth and center frequency establishes it as a versatile and efficient solution for emerging terahertz-based applications, demonstrating significant potential for enhancing the flexibility and functionality of future communication technologies.

Acoustic Response Discrimination of Phulae Pineapple Maturity and Defects using Factor Analysis of Mixed Data and Machine Learning Algorithms

Acoustic response is non-destructive evaluation technique that replicates the conventional method for determining maturity by tapping the fruit. The physical (dimensions, color, firmness, and specific gravity) chemical (TSS, %TA, and TSS/TA), and acoustic properties of Phulae pineapple were determined and used to classify the maturity and defect, e.g. translucency flesh symptoms. Results showed that all physical parameters of the two maturity stages were not significantly different (p>0.05). Translucency flesh (TF) defects were observed in 23.5% and 27.3% of pineappls in the green and green-yellow stages, respectively. The dominant resonance frequency (fn) of Phulae pineapple ranged of 0.057 to 3.010 kHz. All the physical, chemical, and acoustic properties were used to classify for maturity and defects using the factor analysis (FA) technique and machine learning (ML). Results showed that maturity was correctly classified at 84.0% by all parameters, while elected non-destructive parameters (color, specific gravity, and stiffness coefficients) showed lower results for distinguishing pineapples. Random Forest (RF) provided a better classification than other MLs with 99.93% accuracy of maturity classification, while TF classification was 99.59%. Results showed acoustic method integrated with ML was a fast reliable, and cost effective technique for assessing Phulae pineapple quality.

Textured CoZn-18H hexaferrite with enhanced Snoek’s product and suppressed magnetic loss

Modern communications have created a great demand of magneto-dielectric functional materials having low loss and high permeability properties under the sub-6 GHz band. CoZn-18H planar hexagonal ferrites with strong magnetic anisotropy are more promising in meeting these requirements than that of traditional ferrites. The textured CoZn-18H hexagonal ferrites were synthesized by the reactive templated grain growth (RTGG) method to obtain high magnetic resonance frequency without sacrificing permeability. The layered texture composed of flaky hexagonal particles with a high aspect ratio played an important role in obtaining high permeability and high magnetic resonance frequency. The permeability μ′, magnetic loss tangent tan δμ, and performance factor (PF) of the textured CoZn-18H hexagonal ferrite with the highest Snoek’s product (SP = 6.99 GHz) under 3.41 GHz were 1.66, 0.10, and 56.61 GHz, respectively. Compared with the traditional pure dielectric substrate, a planar inverted F antenna (PIFA) working at 3.0 GHz with a miniaturization rate of 18.1 % was simulated based on the textured CoZn-18H hexagonal ferrite. These results demonstrated that the method of preparing textured CoZn-18H hexagonal ferrites without the application of a magnetic field was effective and revealed the potential of textured planar hexagonal ferrites synthesized by the RTGG method of high-frequency and low-loss applications.