Measured Resonance Frequencies Research Articles

LC dynamic signal modelling and analysis of resonant frequency measurement error under rapid eye movements interference

Abstract LC resonant wireless passive intraocular pressure (IOP) sensors measure IOPs by mapping them to the LC resonance frequencies. However, during the sweeping acquisition process of every LC signal frame, possible rapid eye movement (REM) can interfere with the wireless mutual inductance coupling, leading to the signal distortion and resulting in the error of resonance frequency measuring. Currently, there is a lack of modelling analysis of the error generated by REM effect, resulting in absence of guidance for reducing the impact. Therefore here, we start from the perspective of the signal model and establish the LC dynamic signal model of sweeping acquisition. By means of the limit state analysis and Monte Carlo simulation, we analyze the influence of external REM parameters (including REM range and velocity) and internal parameters of the LC sensing system (including the quality coefficient of LC sensor, diameter, and number of turns of the reader coil, signal sweep acquisition speed and period) on the errors. We demonstrated theoretical relationship between the extreme errors with these parameters and verify it through a computer simulation. Based on the results, we propose to optimize the internal parameters of the LC sensing system to reduce the REMs effect on errors, safeguarding the quality of signal acquisition and improving the measurement accuracy.

Comparison of the Young’s modulus of the lead free solder alloy Sn-Ag3.8-Cu0.7 determined by hot tensile tests, ultrasonic measurements and [formula omitted]-Sn single crystal calculations

Sn-based solders are known for their tendency to form coarse grained microstructures. In combination with the high elastic anisotropy of β-Sn, the overall elastic properties and their interpretation require a careful discussion of the structure–property-relationship as elastic constants are often important input parameters for creep or fatigue models. This study therefore investigates the influence of microstructure and testing method on the Young’s modulus E for the widespread lead free solder alloy Sn-Ag3.8-Cu0.7 (SAC387) using bulk specimens. Due to its already high homologous temperature at room temperature (Thom≈ 0.6 = T/Tm for Tm being the melting temperature), hot tensile tests generally bear the risk of superimposed creep deformation. Mechanical testing becomes even more challenging, since yield strengths are usually low for these alloys. Consequently, in addition to the hot tensile tests executed for the engineering strain rate ϵ̇e=1⋅10−3 s−1, two supplemental methods are used to determine the Young’s modulus comprising of the dynamic resonance frequency measurement and the calculation of the Young’s modulus based on single crystal compliance data of the majority phase β-Sn.Young’s moduli yielded from dynamic resonance frequency measurement and calculations based on single crystal compliance data showed comparable results of (E35 °C≈ 55 GPa, E80 °C≈ 51 GPa and E125 °C≈ 48 GPa). Hot tensile tests showed similar data with the largest deviation at 80 °C, where E80 °C≈ 53 GPa was determined. These absolute values and their temperature dependence can be attributed to the microstructure of the cast specimens which show a general preferred orientation of β-Sn grains close to <110> after analysis via electron backscattered diffraction (EBSD). A comparison with literature data revealed significant differences in the Young’s moduli which are likely to be attributed to differences in the preferred orientation of β-Sn grains.

Fabrication of Wafer-Level Vacuum-Packaged 3C-SiC Resonant Microstructures Grown on &amp;lt;111&amp;gt; and &amp;lt;100&amp;gt; Silicon

In this work, the fabrication of wafer-level vacuum packaged 3C-SiC resonators obtained from layers grown on &lt;100&gt; and &lt;111&gt; silicon is reported. The resonant microstructures are double-clamped beams encapsulated by glass-silicon anodic bonding using titanium-based vacuum gettering. Open-loop resonance frequency measurements are performed on the vacuum-packaged devices showing Q-factor values up to 292,000 for &lt;100&gt; and 331,000 for &lt;111&gt; substrates, with a maximum vacuum level around 10-2 mbar inside the encapsulations with Ti getter.

Red and Green Laser Powder Bed Fusion of Pure Copper in Combination with Chemical Post-Processing for RF Cavity Fabrication

Linear particle accelerators (Linacs) are primarily composed of radio frequency cavities (cavities). Compared to traditional manufacturing, Laser Powder Bed Fusion (L-PBF) holds the potential to fabricate cavities in a single piece, enhancing Linac performance and significantly reducing investment costs. However, the question of whether red or green laser PBF yields superior results for pure copper remains a subject of ongoing debate. Eight 4.2 GHz single-cell cavities (SCs) were manufactured from pure copper using both red and green PBF (SCs R and SCs G). Subsequently, the surface roughness of the SCs was reduced through a chemical post-processing method (Hirtisation) and annealed at 460 °C to maximize their quality factor (Q0). The geometric accuracy of the printed SCs was evaluated using optical methods and resonant frequency (fR) measurements. Surface conductivity was determined by measuring the quality factor (Q0) of the SCs. Laser scanning microscopy was utilized for surface roughness characterization. The impact of annealing was quantified using Energy-Dispersive X-ray Spectroscopy and Electron Backscatter Diffraction to evaluate chemical surface properties and grain size. Both the SCs R and SCs G achieved the necessary geometric accuracy and thus fR precision. The SCs R achieved a 95% Q0 after a material removal of 40 µm. The SCs G achieved an approximately 80% Q0 after maximum material removal of 160 µm. Annealing increased the Q0 by an average of about 5%. The additive manufacturing process is at least equivalent to conventional manufacturing for producing cavities in the low-gradient range. The presented cavities justify the first high-gradient tests.

Measurement of Resonant Frequency of Radio Frequency Converter under Conditions of Significant Electromagnetic Losses

The measurement of resonant frequency in radio wave converter under conditions of high electromagnetic losses presents a formidable challenge. This frequency serves as a crucial parameter directly linked to non-electronic quantities, such as spatial separation thresholds or substance consumption levels. Consequently, accurate measurement of these non-electric variables necessitates precise determination of the transmitter's resonant frequency. However, when electromagnetic losses escalate due to control environment properties, achieving such precision becomes daunting. Common methodologies often hinge on assessing resonant frequency via the transmitter's amplitude-frequency characteristic. However, conventional approaches, typically reliant on electron beam tubes with intricate control mechanisms, falter in accuracy amidst substantial electromagnetic transmission losses. This inadequacy undermines the efficacy of current devices. This paper introduces an unconventional method for resonance frequency measurement and underscores the benefits of the device developed through this novel approach compared to existing ones. The proposed method ensures sustained high measurement accuracy even in the face of significant transmitter electromagnetic losses. Central to this method is the measurement of frequencies ω₁ and ω₂ proximate to the resonant circuit's extreme value at points characterized by identical transmission coefficients. Resonant frequency is then determined as the half-sum of these frequencies during symmetrical frequency modulation. This innovative approach promises to overcome the limitations of traditional resonance frequency measurement methods, offering enhanced precision and reliability in challenging electromagnetic environments.

Application of Generalized S-Transform in the Measurement of Dynamic Elastic Modulus

Resonance is commonly used for in situ measurement of the dynamic elastic modulus to evaluate the strength of concrete samples. Many researchers are also exploring the application of this convenient measurement technology for safety monitoring. Nevertheless, the presence of cracks and variations in curing conditions within samples can impact the resonance frequency range, potentially leading to potential inaccuracies in measurements. In order to improve the measurement accuracy of resonance frequency, this study introduces the Generalized S-Transform (GST) algorithm for measuring the dynamic elastic modulus, which utilizes its high time-frequency resolution to scan the power peak-point in non-stationary and transient excitation signals to determine the resonance frequency. For concrete materials with lower consistency, the experimental results verify the high accuracy of this algorithm in measuring resonance frequency compared with Fast Fourier Transform (FFT). This provides a reference for using the algorithm to measure the dynamic elastic modulus in civil engineering applications, such as buildings and bridges.

Elastic moduli from crystalline micro-mechanical oscillators carved by focused ion beam.

The elastic moduli provide unique insights into the thermodynamics of quantum materials, particularly into the symmetries broken at their phase transition. Here, we present a workflow to carve crystalline resonators via focused ion beam milling from small and oddly shaped crystals unsuitable for traditional measurements of elasticity. The accuracy of this technique is first established in silicon. Next, we showcase the capacity to probe changes in the electronic state with a resolution on the measured resonance frequency as small as 0.01% on YNiO3, a rare-earth perovskite nickelate, in which bulk single crystals have typical length scales of ≈40μm. Here, we observe a sharp 0.2% discontinuity in Young's modulus of an YNiO3 cantilever at a magnetic phase transition. Finally, an additional potential of using free-standing cantilevers as a tool for examining the time-dependence of chemical changes is illustrated by laser-heating YNiO3.

A Novel Dual-Band Omnidirectional Horizontally Polarised Antenna Using Slotted Ground for Wi-Fi Applications

This letter explores an innovative approach to designing a compact, dual-band, omnidirectional, horizontally polarised (OHP) patch antenna with a low profile. The antenna’s ground plane is meticulously etched with radial and arch slots to create open-circuited stubs. This design generates two circulating current loops: one beneath the circular patch and the other on the outer side of the circular patch, comprised of four circular stubs. These current loops operate in unison to produce dual-band resonance and in-phase circulating current on the ground at both resonance frequencies. The antenna’s configuration includes four circular stubs formed by printing sequential radial and bent slots beneath the patch. This arrangement generates an omnidirectional radiation pattern in the azimuth plane at the upper resonance frequency. In addition, four open circular stubs outside the patch are integrated into the ground plane cascaded to the inner four stubs to achieve resonance at the lower frequency. The complete dimensions of the proposed antenna configuration are 0.29λ0 × 0.29λ0 × 0.025λ0, with bandwidths of 2.84% and 2.77% corresponding to measured resonance frequencies of 2.457 and 5.27 GHz, respectively. The measured gains are 1.2 dBi at the lower resonance frequency and 0.8 dBi at the upper resonance frequency. Furthermore, the measured roundness of the radiation pattern remains within 1 dB at the lower frequency band and within 2.8 dB at the upper-frequency band.

Low-thermal-budget electrically active thick polysilicon for CMOS-First MEMS-last integration

Low-thermal-budget, electrically active, and thick polysilicon films are necessary for building a microelectromechanical system (MEMS) on top of a complementary metal oxide semiconductor (CMOS). However, the formation of these polysilicon films is a challenge in this field. Herein, for the first time, the development of in situ phosphorus-doped silicon films deposited under ultrahigh-vacuum conditions (~10−9 Torr) using electron-beam evaporation (UHVEE) is reported. This process results in electrically active, fully crystallized, low-stress, smooth, and thick polysilicon films with low thermal budgets. The crystallographic, mechanical, and electrical properties of phosphorus-doped UHVEE polysilicon films are studied. These films are compared with intrinsic and boron-doped UHVEE silicon films. Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM) are used for crystallographic and surface morphological investigations. Wafer curvature, cantilever deflection profile and resonance frequency measurements are employed to study the mechanical properties of the specimens. Moreover, resistivity measurements are conducted to investigate the electrical properties of the films. Highly vertical, high-aspect-ratio micromachining of UHVEE polysilicon has been developed. A comb-drive structure is designed, simulated, fabricated, and characterized as an actuator and inertial sensor comprising 20-μm-thick in situ phosphorus-doped UHVEE films at a temperature less than 500 °C. The results demonstrate for the first time that UHVEE polysilicon uniquely allows the realization of mechanically and electrically functional MEMS devices with low thermal budgets.

A resonance frequency analysis to investigate the impact of implant size on primary and secondary stability.

Recent years have seen a rise in the usage of dental implants to restore lost teeth. The stability of a dental implant is the main factor in determining its success. Implant stability is influenced by various factors. Several approaches have been employed clinically to evaluate stability at different time intervals. One non-invasive way to assess implant stability is by resonance frequency analysis. Utilizing the resonance frequency analysis method, this study seeks to understand how implant length and diameter affect primary and secondary stability. The current prospective study was conducted in the Prosthodontics Department of Institute of Dentistry, CMH Lahore Medical College. The duration of the study was six months. A total of 90 implants of sizes 4.5 x 8.5 mm and 4 x 10mm were placed. Resonance frequency measurements were recorded using Osstell™ AB device for primary stability at implant insertion and at 12 weeks for secondary stability. All the measurements were carried out by only one of the researchers to minimize inter-observer bias. The average primary stability was 70.33±6.60, and the average secondary stability was 71.43±5.44. The data was stratified for age, gender, and implant site, and the mean primary and secondary stability of both sizes didn't show any statistically significant differences. Without forfeiting implant stability, both implant sizes (4 x 10mm and 4.5 x 8.5mm) can be used interchangeably, depending on available space and anatomical constraints.

Resonant cavity method based on RF measurement and simulation for measuring complex permittivity or permeability of RF absorbing materials

Accurate measurement of complex permittivity and/or permeability of radio-frequency (RF) absorbing materials is essential to predict the performances of higher-order-mode damping in damped accelerating cavities or in vacuum chambers. We propose an improved resonant cavity method that can be used as a complement to the widely used Nicolson–Ross–Weir method for measuring the RF characteristics of materials. The conventional resonant cavity method is based on the cavity perturbation theory. However, the measurements are inaccurate when losses in the materials are large. The improved method we propose determines the complex permittivity or permeability of materials from the measured resonant frequencies and Q factors based on eigenmode simulations. Because the reliability on the eigenmode calculation for RF cavities with lossy materials has become sufficiently reliable, determination of complex permittivity and permeability can be achieved using such a simulation software. We demonstrate this method using ferrite HF70 (TDK Corp.), which is useful for RF absorbers in damped accelerating cavities or in vacuum chambers.

On the τf measurement of microwave dielectric ceramics

As a key parameter of microwave dielectric ceramics, the temperature coefficient of resonant frequency (τf) determines the temperature stability of microwave dielectric ceramics and relevant microwave devices. The τf of a microwave dielectric ceramic is typically calculated from the measured resonant frequencies of the system, consisting of the ceramic sample plus other dielectric elements, at two temperatures ∼60 – 70 °C apart. This measurement process assumes that τf is a constant; however, it is generally temperature-dependent based on both theoretical and experimental results. Furthermore, the as-measured τf is actually the τf of the dielectric resonator system, which is different from that of the sample itself. In this paper, these two overlooked problems during τf measurement are discussed in detail, and suggestions are given to avoid their possible misleading consequences and thus ensure the reliability of τf measurements.

Laser-Induced Selective Metallization on Aluminum Nitride for Fine Line Circuits

The technology of laser direct selective metallization on aluminum nitride substrate was investigated for manufacturing fine line circuits. In laser direct structuring, laser activation and electroless copper plating were used. The feasibility was evaluated by analyzing the sieving, contrast, and fine linewidth patterns, and the results showed that the width of the feasible fine reached 100 μm. A near-field communication (NFC) antenna circuit of the width of 400 μm was fabricated on the aluminum nitride substrate. The measured resonance frequency was close to the NFC specification frequency.

Thermal noise calibration of functionalized cantilevers for force microscopy: Effects of the colloidal probe position

Colloidal probes are often used in force microscopy when the geometry of the tip–sample interaction should be well controlled. Their calibration requires an understanding of their mechanical response, which is very sensitive to the details of the force sensor consisting of a cantilever and the attached colloid. We present some analytical models to describe the dynamics of the cantilever and its load positioned anywhere along its length. The thermal noise calibration of such probes is then studied from a practical point of view, leading to correction coefficients that can be applied in standard force microscope calibration routines. Experimental measurements of resonance frequencies and thermal noise profiles of raw and loaded cantilevers demonstrate the validity of the approach.

Resonant ultrasound spectroscopy for textured materials

Resonant ultrasound spectroscopy (RUS) is a method in which the least-squares fitting of a sample's measured resonance frequencies is used to determine the sample material's elastic constants. Difficulties arise when RUS is applied to textured materials, which are composed of crystallites that are neither completely aligned nor randomly oriented; such materials would have effective elastic tensors with 21 independent elastic constants, and this would overburden the conventional RUS analysis process. In any case, the elastic nature of some textured materials may be represented as the weighted average of the elastic tensors of the constituent crystalline material rotated in the directions of the individual crystallites. The collection of weights is the orientation distribution function (ODF). Now the least-squares fitting of a sample's measured resonance frequencies may be used to determine not the sample's elastic constants but instead its ODF. This is not trivial since the weights must be positive and sum to one, but it may be done with a simple modification of the conventional RUS software.

Resonant ultrasound spectroscopy experimental design and optimization

Resonant Ultrasound Spectroscopy (RUS) is a nondestructive material characterization technique that utilizes solid body resonances to estimate elastic moduli. This method is advantageous over traditional mechanical testing due to the significantly lower number of required samples to estimate the same number of moduli. The goal of this project is to develop a high-throughput RUS system capable of measuring experimental resonances and mode shapes in a fraction of the time of traditional RUS measurements. A new system was designed which leverages data/image analysis algorithms to aid in sample alignment and data collection. A standardized sample geometry was also analyzed by performing a geometric sensitivity study and optimizing the aspect ratio of lengths of a parallelepiped. The results show that the optimized sample geometry is consistent between materials with varying elastic properties. In order to validate the design of the new RUS system a comparative study to an existing system was conducted. The results show that the newly designed system produces comparable resonant frequency and mode shape measurements.

Noise and thermal performance of a sub-attofarad capacitance sensor for precision measurements, with applications in gravitational wave detectors.

We describe the design principles, fabrication, and characterization of a precision AC resonant capacitance bridge (RCB) sensor, based on a resonant differential planar printed circuit board transformer with a solid (ungapped) MnZn ferrite core, demonstrating a short-term sensitivity at 293K of 0.225 ± 0.005 aF/√Hz at around 120kHz resonance frequency and 1Hz Fourier measurement frequency. At 120K, the RCB short term noise sensitivity is 0.118 ± 0.005 aF/√Hz. We compare the ungapped configuration to five different RCBs: three with a core gap of 65 μm and two with a core gap of 130 μm. Their average room temperature short term noise sensitivities are 0.30 ± 0.01 and 0.45 ± 0.01 aF/√Hz, while the cryogenic operation of these transformers at 120K resulted in averaged sensitivities of 0.23 ± 0.01 and 0.36 ± 0.01 aF/√Hz, respectively. Multi-hour room temperature runs, with one core of each of the three gap types, proved the stability of their long-term sensitivities of 0.234 ± 0.005, 0.338 ± 0.009, and 0.435 ± 0.010 aF/√Hz for the ungapped (40-h duration) and the 65 and 130 μm (28-h duration) cores, respectively. At 0.1mHz, a critical frequency for space gravitational wave detectors, the respective sensitivities are 0.25 ± 0.02, 0.35 ± 0.02, and 0.53 ± 0.07 aF/√Hz. Measurements with the ungapped transformer configuration for temperatures from 325 to 349K further validate the dependence of the noise model on temperature and permeability. The performance of our RCB with an ungapped core matches the calculated performance value and shows an improvement in signal-to-noise ratio of two or more compared with capacitance bridges developed for similar applications. A further factor of about two noise reductions is achieved by cooling to 120K.

First-in-Human Pilot Study to Assess Methodology for Using a Mineral-Organic Bone Adhesive for Optimization of Primary Stability and Implant Success for Implants Glued into Immediate Extraction Sockets and Immediately Temporized: Pilot Study.

To assess the handling properties and clinical function of a new class of material, a so-called mineral-organic bone adhesive (Tetranite; TN), which as yet has no precedent in orthopedic or oral and maxillofacial surgery, for clinically unstable implants placed in immediate extraction sockets and immediately temporized in the anterior maxilla. A cohort of up to 15 patients requiring between one and four immediate dental implants placed into maxillary extraction sockets from canine to canine were eligible for inclusion. Implants had to be unstable with an insertion torque of < 15 Ncm. Implants were then stabilized using TN, which was allowed to set before reassessing stability using both torque and resonance frequency measurements. Implant stability quotients (ISQs) taken after TN setting were compared to ISQs taken prior to its application, and the implants had to demonstrate resistance to a forward torque of 20 Ncm to be considered stable. ISQs were monitored at 1 week and 1, 3, 7, and 12 months postplacement. In addition, peri-implant tissue health was monitored, adverse events were recorded, and implant success was determined at 1 year postplacement. Eleven patients received a total of 14 implants. Three out of the first six implants failed within 1 month (50%), and thus a protocol amendment was made to remove steps considered potentially destructive to the bonding process. As a result of these amendments, only one further failure was experienced for the next eight implants placed (12.5%). Mean ISQ data averaged for buccolingual and mesiodistal measurements demonstrated a baseline value before TN application of 59.1 Ncm (SD: ± 9.7; range: 40.5 to 73.0). After final setting of the TN, mean ISQ measured 71.9 Ncm (± 6.5; 56.0 to 80.0). At 3 months, just prior to restoration placement, mean ISQ measured 71.0 Ncm (± 6.6; 57.0 to 78.0). Thereafter, the mean ISQ continued to increase at both the 7- and 12-month follow-ups with scores of 78.9 (± 4.6; 72.0 to 84.5) and 80.3 (± 3.8; 74.5 to 85.0), respectively. The surviving 10 implants went on to be fully restored and remained in function beyond the end of the study period to yield a final success rate of 71.4%. The purpose of a first-in-human study is to demonstrate an extrapolation of preclinical data into the controlled human clinical arena. It is an opportunity to learn what does and does not translate well from experimental data. In that regard, the current pilot study can be deemed a complete success. The implant survival rate of 71.4%, while disappointing, should be considered in light of the protocol amendments identified, the user handling experience learned, and the opportunity to modify the material to better perform in the human patient, as all represent important lessons learned. The notable increase in ISQ sheds light on the nature by which the glue was substituted for bone to yield a stable implant by the end of the study period.

Compact Micro-Coriolis Mass-Flow Meter with Optical Readout.

This paper presents the first nickel-plated micro-Coriolis mass-flow sensor with integrated optical readout. The sensor consists of a freely suspended tube made of electroplated nickel with a total length of 60 mm, an inner diameter of 580 µm, and a wall thickness of approximately 8 µm. The U-shaped tube is actuated by Lorentz forces. An optical readout consisting of two LEDs and two phototransistors is used to detect the tube motion. Mass-flow measurements were performed at room temperature with water and isopropyl alcohol for flows up to 200 g/h and 100 g/h, respectively. The measured resonance frequencies were 1.67 kHz and 738 Hz for water and 1.70 kHz and 752 Hz for isopropyl alcohol for the twist and swing modes, respectively. The measured phase shift between the two readout signals shows a linear response to mass flow with very similar sensitivities for water and isopropyl alcohol of 0.41mdegg/h and 0.43 mdegg/h, respectively.

Designing an omnidirectional horizontally polarized circular patch antenna implementing unequal open‐circuited stubs

AbstractA novel method of designing an omnidirectional horizontally polarized (OHP) patch antenna with omnidirectionality in the H‐plane is proposed in this letter. The three pairs of unequal arch slots with three open radial slots are etched on the ground, which is equivalent to three pairs of open‐circuited unequal stubs that excite the TM1.5,1 patch mode and produce two resonance frequencies with circulating in‐phase current on the patch and the ground. Additionally, three pairs of open‐circuited unequal stubs are generated to enhance bandwidth and generate extra resonance frequencies by sequentially printing unequal arch and open radial slots on the top patch. The proposed antenna's 10 dB impedance bandwidth, including all resonance frequencies of TM1.5,1 patch mode, is 10.20%, covering the 2.326–2.576 GHz Wi‐Fi band. The patch and ground diameter are 0.31λ0 and 0.387λ0, respectively, with a real gain of 1.84–1.98 dBi over the operating band, and a gain variation is within 1.3 dB in the H‐plane at two measured resonance frequencies.