kHz Frequency Research Articles

Research on broadband vibration reduction performance of high-damping stainless steel fiberboard

This study investigates the application of stainless steel fiberboards (SFBs) for effective vibration reduction in the head section of autonomous underwater vehicles (AUVs). SFBs offer a compelling combination of lightweight design, high static load capacity, and broad-band vibration reduction. To understand their effectiveness, we analyzed the mechanisms behind SFBs’ superior compressive strength and high-damping properties. Furthermore, a finite element model (FEM) of the AUV head section was created using COMSOL software. The model’s accuracy was validated by comparing simulation results with experimental data. This validated model was then employed to calculate the energy consumption of the bearing plate within the AUV’s head section, providing valuable insights for optimizing SFB design for specific vibration reduction applications. The results demonstrate that SFBs of various thicknesses exhibited higher energy consumption ratios compared to the aluminum plates. This finding reinforces the effectiveness of the SFB’s damping mechanism. Additionally, across the 0–6 kHz frequency range, SFBs significantly outperform the aluminum plates, achieving an average improvement of approximately 18 dB in vibration level difference (VLD). These results highlight the excellent vibration reduction performance of SFBs.

Study of square-wave AC electrophoretic deposition of lithium titanate anodes for Li-ion batteries

Electrophoretic deposition (EPD), while being a scientifically interesting technique due to its inherent versatility, has only limited success in industrial applications. This is partly due to the need to employ expensive and potentially hazardous organic solvents in traditional suspensions. Recently, a significant effort has been focused on the use of aqueous systems and AC-EPD approaches. In this article we present a study and characterization of square-wave electrophoretic deposition at different frequencies of the lithium titanate water-based suspension for application in lithium-ion batteries. We have found that the mass of the deposit linearly increases with time. This reveals that depletion zones are less prone to form in an alternating field, hence enabling formation of homogeneous films and diminishing a growth in bath resistance as compared to DC mode. The EPD performed at critical frequency of 40kHz results in higher content of carbon co-deposited with LTO, improved capacity and power capability and of Li/LTO cells.

A full factorial design for the decolorization of real textile wastewater using iron-rich montmorillonite by sonocatalytic process

In this study, the sonocatalytic process was used to remove colour from the effluent of a textile factory located in Turkey. Clay from a brick-tile factory located in the city of Eskisehir was used to enhance the effect of ultrasound (US) at 20 kHz frequency and 750 W power. The structure, morphology and composition of the clay were identified by characterization studies including FT-IR, XRD, XRF, SEM and TGA. The clay consists mainly of montmorillonite and iron-rich montmorillonite as smectite minerals, nontronite, quartz minerals, calcite and dolomite as minor clay minerals. In the scope of the study, Design of Experiment (DoE) and a Full Factorial Design (FFD) was used to determine the operating conditions that affect the color removal efficiency of textile industry wastewater. pH, clay amount, time, and H2O2 concentration were determined as critical factors using Analysis of Variance (ANOVA). It has been confirmed that when the critical factors for color removal efficiency—specifically, a pH of 2. 2 grams of clay, a duration of 120 minutes, and 35 ppm of H2O2—are kept constant, the resulting removal percentage was predicted as 94% approximately by using regression model. The optimal levels of factors have been verified by the validation experiments.

Stability of sputtered iridium oxide neural microelectrodes under kilohertz frequency pulsed stimulation

Objective. Kilohertz (kHz) frequency stimulation has gained attention as a neuromodulation therapy in spinal cord and in peripheral nerve block applications, mainly for treating chronic pain. Yet, few studies have investigated the effects of high-frequency stimulation on the performance of the electrode materials. In this work, we assess the electrochemical characteristics and stability of sputtered iridium oxide film (SIROF) microelectrodes under kHz frequency pulsed electrical stimulation.Approach. SIROF microelectrodes were subjected to 1.5-10 kHz pulsing at charge densities of 250-1000μC cm-2(25-100 nC phase-1), under monopolar and bipolar configurations, in buffered saline solution. The electrochemical behavior as well as the long-term stability of the pulsed electrodes was evaluated by voltage transient, cyclic voltammetry, and electrochemical impedance spectroscopy measurements.Main results. Electrode polarization was more pronounced at higher stimulation frequencies in both monopolar and bipolar configurations. Bipolar stimulation resulted in an overall higher level of polarization than monopolar stimulation with the same parameters. In all tested pulsing conditions, except one, the maximum cathodal and anodal potential excursions stayed within the water window of iridium oxide (-0.6-0.8 V vs Ag|AgCl). Additionally, these SIROF microelectrodes showed little or no changes in the electrochemical performance under continuous current pulsing at frequencies up to 10 kHz for more than 109pulses.Significance. Our results suggest that 10 000μm2SIROF microelectrodes can deliver high-frequency neural stimulation up to 10 kHz in buffered saline at charge densities between 250 and 1000μC cm-2(25-100 nC phase-1).

Outcomes of primary stapedotomy using ionomeric cement at incus-prosthesis attachment versus nonuse of ionomeric cement: a prospective case–control study

BackgroundStapedotomy is the main stay management of otosclerosis till the present day. Other alternatives are hearing aids and medical treatment. Many complications arise at the step of crimping of the prosthesis. Bone cement is a material that has strong adhesive and osteointegration properties. The aim of the present study is to compare hearing results between bone cement-applied and non-bone cement-applied primary stapedotomy patients at the incus prosthesis attachment.MethodsThirty patients diagnosed with otosclerosis were randomly selected. Classical primary stapedotomy was performed for both groups, except for using GIC over the incus–prosthesis attachment in group A patients. The duration of follow-up was 2 months. Mean thresholds were measured at 0, 1, 2, and 4 kHz frequency levels and used to calculate the primary outcome measurements, which were ABG closure and hearing gain.ResultsThe overall 30 patients’ mean age was 37.2 years. Bilateral disease occurred in 73.3%. Both groups showed significant ABG closure in relation to the preoperative values (P < 0.001). However, ABG closure in cement-used patients was significantly better (P 0.007). The mean for air conduction hearing gain was higher in group A (31.9 dB) than in group B (27.3 dB). However, this was statistically insignificant (P 0.313).ConclusionsGIC can improve hearing outcomes in classical primary stapedotomy and potentially reduce postoperative complications and should be considered in routine practice.

Study on the Co-Combustion Behavior of Municipal Sludge and Bagasse: Evaluation of Ultrasonic Pretreatment

Currently, the production of sludge in China is on the rise annually, and the co-combustion of sludge with biomass for power and heat generation represents a viable method for the bulk treatment of sludge. In this study, we examined the combustion characteristics of municipal sludge (MS), bagasse (BA), and their blends using thermogravimetric analysis. Orthogonal experiments were conducted to assess the impact of ultrasonic pretreatment on the co-combustion properties of MS and BA. Prior to ultrasonic pretreatment, the combustion of BA was characterized by three distinct stages, while MS exhibited two stages. At a 30% MS ratio, the promotional interaction between BA and MS was most pronounced. Following ultrasonic pretreatment, the combustion of BA was simplified to two stages. With a 10% MS mass ratio, ultrasonic pretreatment enhanced the comprehensive combustion characteristic index, thereby improving the combustion performance of the mixture. The activation energy increased post-pretreatment, particularly when the MS content was 50%. Under the conditions of 45 kHz frequency, 500 W power, 3 h duration, and a 10% MS blending ratio, the mixture displayed reduced mass residue, elevated reaction rates, and superior combustion efficiency. This research aims to introduce a novel approach to the harmless disposal, volume reduction, and resourceful utilization of sludge.

Unobstructive and safe-to-wear watt-level wireless charger

A wearable microgrid that centralizes and distributes harvested energy across different body regions can optimize power utilization and reduce overall battery weight. This setup underscores the importance of developing cable-free wireless power transfer (WPT) systems for mobile and portable devices to eliminate the risks posed by wired connections, especially in dynamic and hazardous environments. We introduce a thin, stretchable, and safe hand band capable of watt-level wireless charging through the widely adopted Qi protocol operating at 130 kHz. The implementation of non-adhesive fabric encapsulation serves to protect the 50-μm-thin spiral copper antenna from mechanical strain, ensuring an overall hand band stretchability of 50%. We also create a stretchable “Ferrofabric”, characterized by a magnetic permeability of 11.3 and a tensile modulus of 75.3 kPa, that provides magnetic shielding for the antenna without compromising wearability. The “Ferrofabric” improves the coil inductance but induces core loss in AC application. By fully understanding and managing loss mechanisms such as the skin effect, proximity effect, core loss, and joule heating, we achieve a wireless charging efficiency of 71% and power delivery of 3.81 W in the kHz frequency range. Our WPT hand band is unobstructive to hand motion and can charge a handheld smartphone as fast as a desktop charger or power a battery-free chest-laminated e-tattoo sensor, with well-managed thermal and electromagnetic safety. Through a holistic electromagnetic, structural, and thermal design, our device culminates in a safe, rugged, and versatile solution for wearable WPT systems.

Investigation of the Dielectric Characteristics of Chromium-substituted Zinc and Cobalt Nanoferrite Systems

Abstract The series of Cr-substituted Zn and Co nanoferrite systems having the chemical composition CrxZnFe2–xO4 and CrxCoFe2–xO4 (0.0 ≤ x ≤0.5) were prepared by sol–gel technique. The present investigation aims to compare the impact of Cr3+ concentration on dielectric characteristics of Zn and Co-nanoferrite systems. The investigation of various dielectric characteristics was conducted using an LCR meter at 1kHz frequency and across the frequency range of 100Hz to 1MHz. The measurements were conducted at room temperature. In the case of both ferrite systems, the plots of frequency Vs dielectric constant (ε′) and AC conductivity (σac) show a common dielectric behavior of spinel ferrites. The plots of frequency Vs dissipation factor (D) of Cr- Cr-substituted zinc and Cobalt nanoferrite samples were observed to be unusual and display a relaxation peak at a particular frequency. In the current study, CrxZnFe2-xO4(x=0.2 and 0.3) and CrxCoFe2–xO4 (x=0.3) ferrite samples were found to exhibit very high values of dielectric constant. So these ferrites may be useful for a wide range of applications in electrical storage devices. According to LCR reports, all the Cr3+ substituted ferrite samples in both ferrite systems exhibit higher dielectric constant and AC conductivity values. Possible mechanisms that may be accountable for the outcomes are thoroughly scrutinized in this paper.

Understanding surface morphology changes in stainless steel through stepwise cavitation erosion: A comprehensive study

Cavitation damage, evolution, and features with time are serious problems confronting designers and users of high-speed hydraulic machines. The stepwise erosion technique clarifies the evolution of cavitation damage and its features over time. The technique involves exposing a test sample to repeated very low durations of erosion, followed by accurate relocation in the SEM. This allows fora detailed study of the actual wear processes within a material, providing a solid foundation for understanding material failure. The experiments were conducted using an ultrasonic vibratory horn functioning at 19.5 kHz frequency and 50 µm ± 0.2 um peak-to-peak amplitude. The tested material was cold-rolled austenitic stainless steel SUS 304 (18 Cr-8 Ni). The results show that the slip bands formed due to shock waves’ impact are the preferential sites for early material removals. Material removal starts gradually along the slip bands that form at the grain boundary and then progresses into the grain. The results also showed that the microjets formed pits that were a few micrometers in size and separated from one another. These pits have remained the same shape and size over time, confirming their limited role in the evolution of cavitation damage. The initiation and progression of inherent cracks resulting from plastic deformation, as well as the characteristics of dislodged particles, strongly support the conclusion that shockwave impacts cause fatigue failure as the mechanism of cavitation erosion.

High Spectral Resolution Observations of Propynal (HCCCHO) toward TMC-1 from the GOTHAM Large Program on the GBT

We used new high spectral resolution observations of propynal (HCCCHO) toward TMC-1 and in the laboratory to update the spectral line catalog available for transitions of HCCCHO—specifically at frequencies lower than 30 GHz, which were previously discrepant in a publicly available catalog. The observed astronomical frequencies provided a high enough spectral resolution that, when combined with high-resolution (∼2 kHz) measurements taken in the laboratory, a new, consistent fit to both the laboratory and astronomical data was achieved. Now with a nearly exact (<1 kHz) frequency match to the J = 2–1 and 3–2 transitions in the astronomical data, using a Markov Chain Monte Carlo analysis, a best fit to the total HCCCHO column density of 7.28−1.94+4.08×1012 cm−2 was found with a surprisingly low excitation temperature of just over 3 K. This column density is around a factor of 5 times larger than reported in previous studies. Finally, this work highlights that care is needed when using publicly available spectral catalogs to characterize astronomical spectra. The availability of these catalogs is essential to the success of modern astronomical facilities and will only become more important as the next generation of facilities comes online.

Circulation process of methyl ester production from pretreated sludge palm oil using CaO/ABS catalytic static mixer coupled with an ultrasonic clamp

This study investigates the potential of fused deposition modeling (FDM) three-dimensional (3D) printing techniques for manufacturing catalytic static mixers during biodiesel synthesis. The printed catalytic mixing elements comprises acrylonitrile butadiene styrene (ABS) plastic with 15 wt% calcium oxide (CaO) as a solid catalyst. When the reactants flowed through the CaO/ABS mixing device, the blending and acceleration processes were both significantly impacted. Moreover, their characteristics, performance in biodiesel production, reusability, and economy were analyzed. The effects of methanol to oil (M:O) molar ratio, circulation time, and sonication time on methyl ester (ME) purity were also examined. The results showed that CaO crystals were distributed on the CaO/ABS mixer’s surface, which is crucial for catalytic purposes. During circulation process of ME from pretreated sludge palm oil (PSPO), catalytic static mixer (CSM) and CSM coupled with ultrasound (CSM/US) reactors were employed. The full ultrasonic power of CSM/US reactor of 16 × 400 W (total 6400 W) was operated at 20 kHz frequency. Moreover, the continuous and pulse ultrasonic modes of CSM/US reactor were compared to determine the ME purity and electricity consumption for ME production. For the CSM reactor, 12:1 M:O molar ratio and 8.5 h circulation time were recommended to realize 94.2 wt% ME purity. For the CSM/US reactor, 12:1 M:O molar ratio and 2.25 h circulation time were recommended to achieve 96.5 wt% ME purity. Under the pulsed mode operation, ME purity of 95.09 wt% was achieved, with a reduction in electricity consumption by approximately 37.6 % compared to continuous mode operation. Furthermore, the CaO/ABS catalytic static mixer was determined to be reusable for up to three cycles in both CSM and CSM/US reactors. Thus, CaO/ABS catalytic static mixers assure high purity ME production through FDM 3D printing technology with a CaO solid catalyst.

Investigation of the Effects of Cu and Fe/Cu Doping on ZnO Nanoparticles for Application as a Solid Electrolyte Battery

In this work, investigation is done on the effect of doping with copper (Cu) and iron/copper (Fe/Cu) on zinc oxide (ZnO) nanomaterials synthesized through a cost‐effective wet chemical precipitation method for application as a solid‐state electrolyte battery. The scanning electron microscope with energy dispersive X‐ray spectroscopy is used to investigate the morphology and elements presence in Cu and Fe/Cu‐doped ZnO nanoparticles. The X‐ray diffraction data illustrates that the crystallite sizes of pure ZnO, Cu–ZnO, and Fe/Cu–ZnO nanoparticles are 14.86, 13.35, and 10.66 nm, respectively, at the (101) plan calculated by Debye Scherrer's formula. The UV‐Vis absorption spectrum shows that the band gap energies of ZnO, Cu–ZnO, Fe–ZnO, and Fe/Cu–ZnO nanoparticles are identified as 3.382, 3.690, 3.5, and 3.465 eV, respectively. The electrical characterization revealed maximum impedance in Fe/Cu–ZnO nanoparticles with 400 Ω at 1 KHz frequency in comparison to other samples. The current–voltage (I–V) measurement shows that the current sensitivity and electrical conductivity are both enhanced for Fe/Cu–ZnO nanoparticles. Fe and Cu co‐doping improved the electrical characteristics of ZnO, and the Fe/Cu–ZnO nanoparticles are employed as a solid electrolyte in a battery, which achieved a high specific charge capacity of 657.85 mAh g−1.

Low noise 3 × 3 coupler demodulation scheme based on spectral subtraction with multi-window minimum statistical noise estimation.

To reduce the noise floor in interferometric fiber-optic sensing systems based on 3 × 3 coupler demodulation, this paper proposes spectral subtraction based on multi-window minimum statistical noise estimation to process the two interference signals. This method estimates the noise spectrum of three types of windowed signals, averages these estimation results, and subtracts them from the signal, effectively removing noise from the interfering signal before demodulation, thereby minimizing noise aliasing during demodulation. Subsequently, the ellipse fitting algorithm and the arctangent algorithm are utilized to accomplish signal demodulation. The experimental results indicate that the system's noise floor is reduced by an average of 25 dB within the 0-5 kHz frequency range and achieves a maximum reduction of 30 dB to a level of 0.7 µrad/√Hz at 50 kHz. This scheme does not use additional optics devices, reducing the complexity and cost of the system, and thereby enhancing the feasibility of interferometric fiber optic sensing systems in various environments.

Respiratory disease detection in lung auscultation with convolutional neural networks and CVAE augmentation

The main purpose of this work was to investigate the possibility of detecting respiratory diseases in audio recordings of lung auscultation using modern deep learning tools, as well as to explore the possibility of using data augmentation by generating synthetic spectral representations of audio samples. The ICBHI (International Conference on Biomedical and Health Informatics) dataset was used for training, validation and augmentation. The dataset includes lung auscultations of 126 different subjects, there are a total of 920 sounds, of which 810 have signs of chronic diseases, 75 of non-chronic diseases and 35 with no pathology. The stage of data preprocessing includes discretization to 4kHz frequency, as well as filtering of frequency bands that do not carry information value for the task. In the next step, each sample was transformed into a frequency spectrum and Melspectrograms were generated. To solve the problem of class imbalance, the required number of synthetic spectrograms generated by convolutional variation autoencoders was added. At the stage of building the model, the methods of classical convolutional neural networks were used. The quality of the obtained algorithm was evaluated using a 10-fold cross-validation. Also, to assess the generalization of the proposed method, experiments were performed with the split of audio recordings into training and test sets using patient grouping. Qualitative evaluation of the model was performed using sensitivity, specificity, F1-score and Cohen’s kappa. A score of 98.45% F1-score was achieved for the 5-class classification problem which can contribute to the development of ways to synthesize and augment sensitive medical data. In addition, a cons of existing methods in the generalization of the obtained predictions were revealed, which opens the way for further research in the direction of clinical respiratory diseases detection.

Associations Between Noise Exposure Level, Noise Kurtosis, and Distortion Product Otoacoustic Emissions in Young Workers With Normal Hearing.

Growing evidence has suggested that, in addition to noise exposure level, noise temporal structure (i.e., kurtosis) plays an important role in the development of noise-induced hearing loss, while most of the relevant research has been on the results of pure-tone audiometry. This study focuses on the combined effect of noise exposure level and noise kurtosis on distortion product otoacoustic emissions (DPOAEs) in young workers with normal hearing. A cross-sectional study among young workers in manufacturing industries was conducted in Zhejiang Province, China. Individual noise exposure measurements were performed on participants to obtain an A-weighted noise exposure level normalized to 8 hr (LAeq, 8hr), cumulative noise exposure (CNE), kurtosis, and kurtosis-adjusted CNE (CNE-K). The DPOAE test was performed on the participants and DPOAE levels were obtained. The relationships between noise exposure level, kurtosis, and DPOAE levels were explored by univariate analyses. Furthermore, multivariate regression models were conducted to estimate the combined effects of exposure level and kurtosis after adjusting for age, gender, and use of hearing protection devices. The overall DPOAE curves across frequency bands presented a fluctuating downward trend with increasing frequency. Both exposure level and kurtosis were found to be associated with decreases in DPOAE levels. The multivariate regression model including CNE-K as a joint indicator of complex noise showed an increased R2 compared with the model including CNE. After adjustment for age, gender, and the use of hearing protection devices, significant effects of CNE-K on DPOAE levels were observed at 3, 4, and 5 kHz frequencies, with maximum effect presented at 4 kHz. DPOAE is a sensitive test that can detect cochlear damage in limited areas that cannot be detected by conventional audiometry. The present study provided a more comprehensive understanding of the impact of complex noise on the DPOAE levels. It also suggested that CNE-K was an effective metric in assessing DPOAE levels associated with complex noise.

Investigation and Fabrication of Brilliant Green Dye Material-Based Organic Heterojunction: Dielectric Response and Impedance Spectroscopy

Brilliant green (BG) dye material-based heterojunction is fabricated by a spin coating route and characterized by impedance analyzer. Here, we study the impedance spectroscopy of such organic material based thin film onto silicon substrate. The capacitance and conductance versus voltage (C-V), (G-V) characteristics are plotted. So, the dielectric response of BG based heterojunction is studied via the plotting of the dielectric constant, modulus components, complex impedance and Nyquist diagram. Real and imaginary parts of electrical conductivity are also plotted at several frequencies. Real and imaginary parts of electric modulus M’-V and M”-V are investigated for all experimental frequencies. The Z’-V characteristics of our device-based BG organic heterojunction exhibit a peak of 1383 W. It is confirmed that an anomalous peak of Z’ is recorded within 0.5-1 V range. The drastic decay in Z”-V plot occurs for lower 100 and 200 kHz frequency range and Z” values become constant beyond 1V for all frequencies. Ac and Dc conductivity curves demonstrate a growth with frequency and angle phase approaches to 90º within reverse voltage. This result reveals a capacitive conduct of our device.

Design of compact signal source with reduced phase noise for airborne pulse Doppler RF sensor

Abstract In this article, a low phase noise signal source to be used as local oscillator in pulse Doppler radio frequency (PDRF) sensor is proposed. Innovative design techniques for realization of the low phase noise frequency source using phase-locked loop (PLL) and dielectric resonator (DR) are presented. Qualitative investigations have been carried out on the effect of phase noise in PDRF sensor performance. An X-band vibration resistant PLL-based frequency source with phase noise better than −95 dBc at 1 kHz frequency offset has been designed here. It also presents the design of a 7.6 GHz low phase noise, vibration resistant DR oscillator. Systematic analysis of the key design aspects, their thermal-vibrational stability, and ease of integration with hybrid microwave integrated circuits have been disclosed. A prototype board is fabricated, assembled in a compact mechanical enclosure of dimension 55 × 55 × 15 mm3. Finally, developed module is experimentally validated under 7.6 g rms magnitude random vibration test in three axes and compared results with other state of-the-art similar works. The comparison clearly shows the merit of present research work over other similar existing works.

Surface-Modified Iron Oxide Nanoparticles with Natural Biopolymers for Magnetic Hyperthermia: Effect of Reducing Agents and Type of Biopolymers

Magnetic fluid hyperthermia, a minimally invasive localized therapy that uses heat generated by magnetic nanoparticles under an AC magnetic field, is a complementary approach for cancer treatment that is excellent due to its advantages of being noninvasive and addressing only the affected region. Still, its use as a stand-alone therapy is hindered by the simultaneous requirement of nanoparticle biocompatibility, good heating efficiency, and physiological safe dose. To overcome these limits, the biocompatible magnetic nanoparticles’ heating efficiency must be optimized. Iron oxide nanoparticles are accepted as the more biocompatible magnetic nanoparticles available. Therefore, in this work, superparamagnetic iron oxide nanoparticles were synthesized by a low-cost coprecipitation method and modified with starch and gum to increase their heating efficiency and compatibility with living tissues. Two different reducing agents, sodium hydroxide (NaOH) and ammonium hydroxide (NH4OH), were used to compare their influence. The X-ray diffraction results indicate the formation of a single magnetite/maghemite phase in all cases, with the particle size distribution depending on the coating and reducing agent. Citric acid functionalized water-based ferrofluids were also prepared to study the heating efficiency of the nanoparticles under a magnetic field with a 274 kHz frequency and a 14 kAm−1 amplitude. The samples prepared with NaOH display a higher specific loss power (SLP) compared to the ones prepared with NH4OH. The SLP value of 72 Wg−1 for the magnetic nanoparticles coated with a combination of starch and gum arabic, corresponding to an intrinsic loss power (ILP) of 2.60 nWg−1, indicates that they are potential materials for magnetic hyperthermia therapy.

A gold nano-urchin-decorated quasi-freestanding graphene-based humidity sensor with enhanced responsivity and a wide relative humidity detection range for real-time applications

Excellent humidity response and detection threshold are essential attributes of a humidity sensor. In this study, quasi-freestanding graphene (QFSG) was grown epitaxially on vicinal silicon carbide via thermal annealing, followed by decoration with hydrophilic gold nano-urchins (AuNUs). The resulting humidity sensor consistently achieved highly effective non-contact humidity-sensing performance, which can be used to monitor breathing and skin moisture. The proposed humidity sensor demonstrated a non-linear response of ∼119.98 % over a wide relative humidity detection range of 4–96 % at a frequency of 1 kHz, outperforming a QFSG-only humidity-sensing device (∼11.92 % and 22–84 % relative humidity, respectively). This 10-fold increase in humidity response and wider detection range is attributed to the hydrophilicity and plasmonic behavior of the AuNUs. It also demonstrated transient impedance response/recovery time of 4.5 and 3.0 s, respectively; low hysteresis of 3.6 %; and stability over 25 days, which are key factors for effective humidity sensing. The fast response and sensitivity of the AuNUs/QFSG humidity sensor made it possible to test for various real-time monitoring applications such as human breathing and non-contact proximity testing.

Contactless femoral implant stability monitoring in cementless total hip arthroplasty, A step towards clinical implementation

The clinical implementation of currently used devices for intraoperative fixation monitoring of femoral implants via vibration-based methods in cementless total hip arthroplasty is challenging, due to practical and regulatory issues. Motivated by the effectiveness of electromagnetic excitation in similar dental applications, this study investigates the use of electromagnetic excitation for femoral implant stability monitoring during cementless total hip arthroplasty. The results obtained from electromagnetic excitation were largely consistent with reference results obtained through impact excitation, with a Pearson Correlation Coefficient of 0.79 in the 0.1–8 kHz frequency band. Moreover, the peak frequencies obtained via the two methods yielded a relative difference of 0.20 ± 0.22 %. Next, the excitation device was successfully utilized in conjunction with a laser vibrometer to monitor the stability of the femoral implant during an in vitro insertion, proving the feasibility of contactless implant stability monitoring. These results indicate the promising potential of this contactless method for clinical implementation.