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The reference polymers and polymers with molecular imprints of carboxylic acids (MIPs-CA)—propionic (MIP-Propionic) and butyric (MIP-Butyric) acids—were synthesized on the surface of piezoelectric sensors using aromatic compounds by the non-covalent imprinting method. A molecularly imprinted polymer (MIP) is a polymer produced through molecular imprinting, which leaves cavities in the polymer matrix with affinity for a chosen "template" target molecule. The values of the imprinting factor and selectivity coefficients were calculated to assess the ability of MIPs-CA to recognize the target molecules. It was shown that the sensors modified by the molecularly imprinted polymers exhibited high selectivity for the acid that was a template during their synthesis. The detection limits for propionic and butyric acids were 7.40 × 10–6 and 8.81 × 10–6 g/dm3, respectively. Correctness of the carboxylic acid determination in model solutions was verified in the spike/recovery tests. The relative standard deviation was less than 10%. The modified piezoelectric sensors were tested in analysis of the intermediate products of edible ethanol production (distillate of fermentation mixture, epurate, bottom liquids of columns). The correctness of the determination of carboxylic acids in liquids was evaluated using an Agilent Technologies 7890B GC System. The difference in the results of acid determination between both methods (piezoelectric sensor and chromatography–mass spectrometry) did not exceed 6%. The modified piezosensors expand the potential of rapid determination of carboxylic acids in the intermediate products of ethyl alcohol production. [ABSTRACT FROM AUTHOR]

Nowadays, in the face of continuous technological progress and environmental requirements, all manufacturing processes and machines need to be optimized in order to achieve the highest possible efficiency. Agricultural machines such as seed drills and cultivation units are no exception. Their efficiency depends on the amount of sowing material to be used and the patency of seed transport tubes or colters. Most available control systems for seed drills are optical ones whose operation is not effective when working close to the ground due to large dusting. Thus, there is still a need to provide seed drills with sensors to be equipped with control systems suitable for use under conditions of massive dusting that would shorten the time of reaction to clogging and be affordable for every farmer. This study presents an analysis of grain motion in the sowing system and an analysis of the operation efficiency of an original piezoelectric sensor with patent application. The novelty of this work is reflected in the new design of a specially designed piezoelectric sensor in the sowing unit, for which an analysis of indication errors was carried out. A seed arrangement of this type has not been described so far. An analysis of the influence of the seed tube tilt angle and the type of its exit hole end on the coordinates of the grain point of collision with the sensor surface and erroneous indications of the amount of sown grains identified by the piezoelectric sensor is presented. Low values of the sensor indication errors (up to 10%), particularly for small tilt angles (0° and 5°) confirm its high grain detection efficiency, comparable with other sensors used in sowing systems, e.g., photoelectric, fiber or infrared sensors and confirm its suitability for commercial application. The results presented in this work broaden the knowledge on the use of sensors in seeding systems and provide the basis for the development of precise systems with piezoelectric sensors.

Pedestrian counting has attracted much interest of the academic and industry communities for its widespread application in many real-world scenarios. While many recent studies have focused on computer vision-based solutions for the problem, the deployment of cameras brings up concerns about privacy invasion. This paper proposes a novel indoor pedestrian counting approach, based on footstep-induced structural vibration signals with piezoelectric sensors. The approach is privacy-protecting because no audio or video data is acquired. Our approach analyzes the space-differential features from the vibration signals caused by pedestrian footsteps and outputs the number of pedestrians. The proposed approach supports multiple pedestrians walking together with signal mixture. Moreover, it makes no requirement about the number of groups of walking people in the detection area. The experimental results show that the averaged F1-score of our approach is over 0.98, which is better than the vibration signal-based state-of-the-art methods.

Abstract Most commercially available cochlear implants and hearing aids use microphones as sensors for capturing the external sound field. These microphones are in general located in an external element, which is also responsible for processing the sound signal. However, the presence of the external element is the cause of several problems such as discomfort, impossibility of being used during physical activities and sleeping, and social stigma. These limitations have driven studies with the goal of developing totally implantable hearing devices, and the design of an implantable sensor has been one of the main challenges to be overcome. Different designs of implantable sensors can be found in the literature and in some commercial implantable hearing aids, including different transduction mechanisms (capacitive, piezoelectric, electromagnetic, etc), configurations microphones, accelerometers, force sensor, etc) and locations (subcutaneous or middle ear). In this work, a detailed technical review of such designs is presented and a general classification is proposed. The technical characteristics of each sensors are presented and discussed in view of the main requirements for an implantable sensor for hearing devices, including sensitivity, internal noise, frequency bandwidth and energy consumption. The feasibility of implantation of each sensor is also evaluated and compared.

Membrane systems are increasingly being used for treating water, wastewater, and reused water. However, membrane damage can decrease removal efficiency and hinder downstream applicability. Thus, the operating conditions of the membrane should be monitored. This study monitored the operating conditions of the membrane using lead zirconate titanate (PZT)-based electro-mechanical impedance (EMI) measurements in an external air pipe. Pilot-scale tests were performed to verify the performance of the proposed method. A pressure decay test (PDT) was performed using a PZT-attached air pipe, in which the pressure was measured using PZT, and a pressure gauge was employed to measure the reference pressure. The EMI signals changed according to the variations in the pressure inside the steel air pipe. To index the signal variation, the amplitude of the major peak was extracted and compared with the reference pressure. The amplitude of the major peak was inversely proportional to the pressure change. The pressure estimation equation was derived using a linear regression between the amplitudes of the major peak and the reference pressures. According to the results, the proposed monitoring system that utilizes the EMI of an external steel pipe is a potential solution to improve the sensitivity and speed of the PDT.

Mechanomyography (MMG) is a technique of recording muscles activity that may be considered a suitable choice for human–machine interfaces (HMI). The design of sensors used for MMG and their spatial distribution are among the deciding factors behind their successful implementation to HMI. We present a new design of a MMG sensor, which consists of two coupled piezoelectric discs in a single housing. The sensor’s functionality was verified in two experimental setups related to typical MMG applications: an estimation of the force/MMG relationship under static conditions and a neural network-based gesture classification. The results showed exponential relationships between acquired MMG and exerted force (for up to 60% of the maximal voluntary contraction) alongside good classification accuracy (94.3%) of eight hand motions based on MMG from a single-site acquisition at the forearm. The simplification of the MMG-based HMI interface in terms of spatial arrangement is rendered possible with the designed sensor.

Copyright of Technisches Messen is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Structural health monitoring (SHM) is becoming increasingly attractive for its potentialities in many application contexts, such as civil and aeronautical engineering. In these scenarios, modern SHM systems are typically constituted by a multitude of sensor nodes. Such devices should be based on low-cost and low-power solutions both to ease the deployment of progressively denser sensor networks and to be compatible with a permanent installation; this allows real-time monitoring while reducing the global maintenance costs. Among the developed inspection methodologies, operational modal analysis (OMA) is an efficient tool to assess the integrity of vibrating structures. This article describes a sensor network that is based on either microelectromechanical systems (MEMS) accelerometers or cost-effective piezoelectric devices to extract strictly synchronized modal parameters. The performances of the two sensing technologies are evaluated in two different setups, to assess the reliability in the estimation of modal features even in the presence of potential damages. Particular attention was given to the mode shape reconstruction issue from piezoelectric signals, primarily encompassing a purposely developed modal coordinate tuning procedure. Moreover, the consistency of the obtained results paves the way to a more compact and affordable monitoring system exploiting piezoelectric-driven modal analysis. [ABSTRACT FROM AUTHOR]

Conditions of the synthesis of nanoparticles of ractopamine molecularly imprinted polymers (MIP) by the precipitation method are studied. It is shown that the size and dispersity of MIP particles are largely determined by the nature of the functional and cross-monomers and by the synthesis conditions: temperature, mixing rate, duration of synthesis, and ultrasonic treatment of the polymerization mixture before and after the synthesis. It is found that ractopamine MIP particles based on methacrylic acid and ethylene glycol dimethacrylate, sonicated for 30 min, have a minimum size and degree of dispersion. Using the piezoelectric quartz micro-weighing method, characteristics of the recognition layer based on MIP nanoparticles are found, and the analytical characteristics of a sensor for the determination of ractopamine in an aqueous solution are calculated. [ABSTRACT FROM AUTHOR]

Membrane filtration is a technology that removes contaminants or impurities from water by passing water through membranes; it has various applications such as in water and sewage treatment. However, a disadvantage of this method is that it has difficulties responding to cases of accidental water pollution or membrane damage. Therefore, membrane damage should be monitored to prevent the contamination of drinking water. In this study, the membrane integrity test was performed by measuring the high-frequency electromechanical impedance (EMI) using a piezoelectric sensor. An attached piezoelectric sensor can detect changes in the physical properties of the membrane due to inner pressure changes. During the pressure decay test, the pressure drop due to membrane damage can be determined by measuring the EMI through an attached piezoelectric sensor. A real-scale test was performed to verify the proposed technology. During the experiment, 20 measurements were taken at each pressure step to increase reliability. According to the results, membrane damage can be monitored by detecting microscopic pressure drops using our proposed method. [ABSTRACT FROM AUTHOR]

In this paper, a measurement system of swallowing motion is developed. A piezoelectric film is used as sensitive material of the sensor to measure the body surface deformation due to swallowing. We focused on laryngeal prominence and digastric muscle which are active during swallowing and developed sensors to attach to skin above laryngeal prominence and digastric muscle. As a result of experiments, it was confirmed that output fluctuation occurred at the swallowing. Next, by comparing the frequency spectral density distribution of sensor outputs during swallowing and resting, it was found that the output waveform during swallowing is mainly composed of larger frequency components below 20 [Hz] than that during resting. From the results, it was suggested that the developed measurement system is available to detect the swallowing from skin deformation without obstructing the motion. [ABSTRACT FROM AUTHOR]

The quaternary ammonium salt of crosslinked chitosan prepared by chemical crosslinking method was used as the flexible substrate. After micro-stretching, PEDOT: PSS was brushed on it to prepare the flexible electrode. Further, the flexible piezoelectric sensor was obtained by assembling the flexible electrode with the self-made PVDF-TrFE/ZnO quantum dot composite piezoelectric film. The quasi-static d33 tester was used to test the piezoelectric strain constant of the piezoelectric film, and the mechanical and electrical properties of the flexible electrode were tested by universal tensile testing machine and multimeter, respectively. The output performance of the piezoelectric sensor was tested by excitor test. The results show that the tensile strength of flexible electrode was 3.3 MPa and the elongation at break was 762.3%. The resistance of flexible electrode was 1.68 Ω H. The d33 piezoelectric constant of PVDF-TrFE /ZnO film with two layers of spin coating was 26.1 pC/N. The output voltage of the fully flexible piezoelectric sensor was 4.46 V. [ABSTRACT FROM AUTHOR]

To account for the temperature effect on guided wave signals in complex structures, a significant amount of baseline measurements typically need to be collected over a large temperature range to serve as a library of signals at all possible temperatures, which, if not impossible, is highly impractical. This article presents a data-driven temperature baseline reconstruction approach that is applicable for various structures made from the same material. The influence of temperature on the amplitude and phase of guided wave measurements are experimentally quantified as dimensionless compensation factors. The derived compensation factors are used to reconstruct baselines at various temperatures for guided wave measurements in a simple flat plate and a stiffened panel. With a single baseline measurement at 20°C and the reconstructed baseline using the predetermined temperature compensation factors, impact damage was successfully detected and located when current measurements were up to 25°C and 20°C higher than the baseline temperature, respectively. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) has been applied in various industries due to its excellent piezoelectric property. In this study, the optimization of various processing conditions such as poling strength, poling duration and the surface morphology (angle) of the sensors were systematically investigated for large-area tactile sensor based on a 0.8 mm-thick film. Specifically, the performance parameters of the tactile sensor such as sensitivity, responsibility and response against loading forces were investigated. Since the tactile sensor was fabricated via a combination of 2D and 3D printing processes, this process can be practiced in the industry to fabricate large-size tactile sensors based on PVDF based piezoelectric devices. [ABSTRACT FROM AUTHOR]

The charge amplifier is an important building block in various electronic circuits. In this paper a new charge amplifier for piezoelectric sensors is introduced. The advantages of the new proposed charge amplifier becomes obvious in the quasi-static applications. In some quasi-static applications the traditional charge amplifiers uses an extremely large feedback resistor (in the range of $\text{G}\Omega $) whereas the proposed charge amplifier no longer requires such extremely large resistors. Moreover the proposed circuit reduces the output offset voltage significantly in comparison with conventional charge amplifier. The proposed circuit can be also implemented by using general purpose JFET operational amplifiers instead of using electrometer operational amplifiers therefore the cost of implementation will be reduced significantly in comparison with conventional charge amplifier. The proposed charge amplifier was assembled by using general purpose JFET Op-Amp to capture and amplify the output voltage of the piezoelectric vibration sensor Minisense100. In this experiment the low-cutoff frequency and the gain of the proposed charge amplifier were set equal to 0.2Hz and 20.5 dB respectively. The output offset voltage of the circuit was measured equal to 210 $\mu \text{V}$.The measurement of very small vibration (±0.015g) showed a relative error equal to 2.1% with respect to the value which is obtained by using vibration meter as reference. [ABSTRACT FROM AUTHOR]

Structural damage detection using unmanned Structural Health Monitoring techniques is becoming the need of the day with the technologies available presently. Sensors made of Lead Zirconate Titanate materials, due to their simplicity and robustness, are increasingly used as an effective monitoring sensor in Structural Health Monitoring. Continuous monitoring of the structures using Lead Zirconate Titanate sensors often results in a laborious data retrieval process due to the large amount of signal generated. To speed up the data retrieval process, a multi-sensing technique in which the Lead Zirconate Titanate patches are connected in series and parallel is proposed for structural damage detection. The proposed method is validated using an experimental investigation carried out on a reinforced concrete beam embedded with smart Lead Zirconate Titanate sensor units. The beam is subjected to damage, and the location of damage is identified using conductance signatures obtained from patches sensed individually and through multiplexing. This article proposes an effective methodology for selection of patches to be connected in series/parallel to maximise the efficiency of damage detection. Damage quantification using conventional statistical metrics such as root mean square deviation, mean absolute percentage deviation and cross correlations are found to be ineffective in identifying the location of damage from the multiplexed signatures. In turn, dynamic metrics such as moving root mean square deviation, moving mean absolute percentage deviation and moving cross correlation with overlapped moving blocks of data are proposed in the present work and their ability to detect the damage location from multiplexed signatures is discussed. [ABSTRACT FROM AUTHOR]

A new wind sensing device based on bimorphs array is designed for apperceiving wind direction and velocity, whose structure is an L-shaped cantilevers array. A coupling model of the array is proposed to predict the response voltage stimulated by wind. By extracting the response voltage ( U m ) on each bimorph cantilever, the values of wind direction ( α n , cal ) and velocity ( v n , cal ) can be calculated in terms of the geometric relation. Further, the relations among wind errors, array amounts (m) and array radius (r) are acquired, and m & r can be utilized to decreasing angle error ( E α n ¯) and velocity error ( E v n ¯) of wind. The calculated and experimental results show that, increasing m initially yields decreasing these two errors, then it begins to increase the errors when m is larger than 6. The minimal wind angle and velocity errors of the array are 0.14° and 0.34%, respectively, at actual wind of 13.4 m/s, m = 6 and r = 20 mm. Meanwhile, increasing r can decrease E v n ¯ and E α n ¯ , Besides, for calculating 20 random incidence wind angles, respectively, the range of wind velocity error is from 0.34% to 0.87%, the range of wind angle error is from 0.12°to 0.38°, and the response time is 10 ms. [ABSTRACT FROM AUTHOR]

Welding force is a core parameter of Friction Stir Welding, whose accurate measurement and characterisation is an important guarantee for the welding quality of Friction Stir Welding. In this paper, the load ratio calculation method for calibrating force is proposed based on piezoelectric measurement system. The mathematical model and test model of piezoelectric dynamometer with parallel layout, both share-loading pillars and piezoelectric sensors, are designed based on piezoelectric sensors' structure of four-point square layout, calibration tests for piezoelectric dynamometer are accomplished, and the calibration curves between different loading positions and output voltage of sensors with different standard forces based on Lagrange polynomial interpolation method are obtained. A novel load ratio calculation method is proposed, which solves the problem that there is larger deviation for axial output of piezoelectric sensor when force loads on different loading positions and achieves accurate measurement and calibration for external forces. And the calculated result demonstrates that the largest axial error is less than 1%, which verifies the feasibility and effectiveness of the load ratio calculation method. [ABSTRACT FROM AUTHOR]

For a structural health monitoring (SHM) system, the operational functionality of sensors is critical for successful implementation of a damage identification process. This study presents experimental and analytical investigations on sensor fault diagnosis for impedance-based SHM using the piezoelectric interface technique. Firstly, the piezoelectric interface-based impedance monitoring is experimentally conducted on a steel bolted connection to investigate the effect of structural damage and sensor defect on electromechanical (EM) impedance responses. Based on the experimental analysis, sensor diagnostic approaches using EM impedance features are designed to distinguish the sensor defect from the structural damage. Next, a novel impedance model of the piezoelectric interface-driven system is proposed for the analytical investigation of sensor fault diagnosis. Various parameters are introduced into the EM impedance formulation to model the effect of shear-lag phenomenon, sensor breakage, sensor debonding, and structural damage. Finally, the proposed impedance model is used to analytically estimate the change in EM impedance responses induced by the structural damage and the sensor defect. The analytical results are found to be consistent with experimental observations, thus evidencing the feasibility of the novel impedance model for sensor diagnosis and structural integrity assessment. The study is expected to provide theoretical and experimental foundations for impedance monitoring practices, using the piezoelectric interface technique, with the existence of sensor faults. [ABSTRACT FROM AUTHOR]

A proof-of-concept method for measuring cardiac tissue contraction force using an in-house-developed piezoelectric cantilever sensor system is demonstrated. Contracting forces of 7.2–16.6 μN (n = 5) were measured from a human cardiac tissue construct. Beating cardiac tissue constructs were monitored in-situ under a microscope during the contraction force measurements. Development of the measurement method allows very low forces such as the ones that appear in biological small scale systems to be determined. Image 1 • Direct measurement of contraction force of cardiac tissue construct. • Contracting forces of 7.2–16.6 μN measured from human cardiac tissue construct. • In-house developed piezoelectric cantilever sensor based measurement method. [ABSTRACT FROM AUTHOR]

High-accuracy measurement of force affects real-time control and process adjustment of industrial production. Piezoelectric sensor can be applied to measure force with the characteristics of high frequency and stiffness, great dynamic response and resistance to harsh conditions. As an important part of test, calibration determines sensitivity coefficient which directly affects test accuracy. To improve the calibration accuracy of offset loading force for multisensor piezoelectric dynamometer, a novel calibration method using sensor sensitivity difference is proposed in this paper. The calibration experiments of four sensors are performed to obtain the axial sensitivities and the force-to-electricity conversion coefficients. The multiple loading-point (MLP) calibration experiments of dynamometer are carried out, and the calibration results prove that the sensitivity difference of four sensors is the main reason affecting the calibration accuracy. The sensitivity difference calibration method (SDCM) is applied to the MLP calibration experiments, and the results show that the average resultant force deviations are reduced from 418.79 N (8.38% full scare (FS) to 24.16 N (0.61% FS) under a loading force of 5000 N, which proves high accuracy and reliability of SDCM. The calibration method will provide guidance for improving the calibration accuracy of dynamometer. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Test & Measurement Technology is the property of Publishing Center of North University of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Partial discharge (PD) is the main cause of the insulation decay and hence periodical testing of the insulation condition of a distribution transformer is necessary. This paper presents a model of PD acoustic wave propagation, detection, and localization in an oil-filled distribution transformer using finite element method supported by COMSOL Multiphysics software. Using an acoustic module and AC/DC module of COMSOL Multiphysics software, oil filled distribution transformer, and the acoustic piezoelectric sensor are simulated to analyze and detect the PD inside the transformer. PD is numerically simulated in the transformer windings, core, and oil ducts that produce acoustic wave signal. The distribution of the acoustic pressure wave inside the model transformer is analyzed first. Next, the acoustic piezoelectric sensors are modelled at four different locations of the model transformer to detect the pressure acoustic wave signal induced due to PD in the transformer. Finally, using an artificial neural network (ANN), the localization, and identification of PD in various parts of the transformer have been analyzed. The results obtained for location and detection are quite encouraging. [ABSTRACT FROM AUTHOR]

Carrying out any experimental studies related to the measurement of vibration there are impossible without calibrating of sensors. The objective of calibration is to determine the sensitivity in the operating range of frequencies and amplitudes. For this purpose developed a technique and assembled the device with unified software package in LabVIEW programming environment.

This work presents an underwater acoustic sensor featuring a radial polarized piezoelectric diaphragm, which aims to work in d 33 mode to enhance its performance. For the sake of accomplishing the in-plane polarization, interdigital electrodes based on semi-circular ring patterns are designed on both sides and aligned along the thickness direction of the diaphragm. Effects of electrode parameters on the polarization orientation are numerically analyzed by the conversion relationship between different coordinates. Using the Kirchhoff plate theory and Rayleigh-Ritz method, a mathematical model is developed to investigate the dynamic properties of the sensor. The results indicate that the output voltages increase with the increase of the electrode inner radius, width, and spacing but decrease with the increase of the diaphragm thickness and radius. Sensor prototypes are fabricated by the microelectromechanical system (MEMS) technology in a clean room and characterized by impedance spectrums. An underwater testing system is established to conduct the experimental verification, whose results are in good accord with those of mathematical modeling. The sensor output voltage has fine linearity with the underwater acoustic pressure and achieves a flat frequency response. Moreover, the sensor has a sensitivity of −172.7 dB (Ref. 1 V/μPa) superior to the reported devices in the same categories. This work provides significant guidance for modeling radial field piezoelectric diaphragms and designing more efficient piezoelectric microsensors, which have a fine application prospect in underwater acoustic measurement. [ABSTRACT FROM AUTHOR]

Recently, enhancing health through sensible exercise has become a pursuit for many. However, the public's limited understanding of scientific exercise methods often leads to sports injuries and even fatal incidents. We propose a Real-time Health Evaluation System (RHES) using arch piezoelectric sensors for capturing pulse signals. An arch-type flexible piezoelectric sensor encapsulated by polyvinylidene fluoride and polydimethylsiloxane (PVDF/PDMS) which provides linear sensitivity, response repeatability, and biocompatibility. A Multi-attention One-dimensional Convolutional Neural Network (MA1DCNN) was utilized to evaluate the regression prediction of the pulse signals with a predicted R-squared of 0.89. RHES, deployed on an upper computer, not only facilitates effective human-computer interaction but also serves as a daily exercise assistant, helping users to objectively evaluate their real-time health status and mitigate injury risks during physical activities. Consequently, RHES merges technological advancement with health maintenance, providing a promising avenue for safe, scientifically backed physical exertion. [ABSTRACT FROM AUTHOR]

• Efficient seeding quality detection with piezoelectric sensors. • VTPD-AM algorithm for analyzing piezoelectric impact sensor signals. • High seed detection accuracy (>97 %) for multiple seed types. • Real-time implementation advantage and outperforms other algorithms. One of the crucial issues in seeders and grain drills is measuring the seed flow rate and seeding quality during the seeding operation. An impact sensor based on a piezoelectric sensor was designed and tested for different seeds to detect seeding quality rapidly and accurately in precision seeders. This sensor enables faster and more cost-effective seeding quality determination than grease belt test benches. Seed impact vibrations were detected using a piezoelectric microphone attached to the plate, while seed trajectories were simultaneously recorded with a high-speed camera. The novelty of this work lies in the implementation of a new algorithm called Variable Threshold Peak Detection with Automatic Calculation of Minimum Threshold (VTPD-AM), which enables more efficient signal analysis. The seed detection accuracy of VTPD-AM was comprehensively compared with the literature, specifically the works of Palshikar et al. (2009), Scholkmann et al. (2012) , and Ozbek et al. (2014). The performance of the tested algorithms was compared using corn, soybean, and sunflower seeds at simulated forward speeds of 6 and 12 km/h. Based on the experimental results, the algorithm presented in this work (VTPD-AM) and the algorithm developed by Ozbek et al. (2014) achieved the highest seed monitoring accuracy (over 97 %). The advantage of VTPD-AM is that it can be implemented on microcontrollers for real-time applications. In all cases, the percentage of undetected seeds increased with the increase in the seed flow rate. [ABSTRACT FROM AUTHOR]

• Enhancing the seed detection accuracy of piezoelectric impact sensors. • Identifying fiberglass as the optimal choice for precise seed measurement. • Demonstrating that the use of fiberglass plates results in a seed detection accuracy exceeding 95% Precision seeders are crucial in modern agriculture as they directly affect agricultural productivity by ensuring the uniform distribution of seeds in the field. Any non-uniformity in seed distribution can lead to missed or multiple seedings, resulting in potential yield losses. To overcome this issue, researchers have dedicated significant efforts to developing efficient and precise methodologies for assessing and enhancing the seeding performance of precision seeders. Piezoelectric impact sensors are widely used for detecting impacts or collisions and can measure the magnitude and duration of such impacts. This study explores a method to improve the reliability and accuracy of seed detection using piezoelectric signal acquisition and analysis to evaluate the seeding performance of precision seeders. A fast and high-precision piezoelectric detection system was designed and tested using steel, acrylic, medium-density fiberboard (MDF), fiberglass, and autoclaved aerated concrete (AAC) as plate materials. The results demonstrated that fiberglass exhibited the highest measurement accuracy, exceeding 95 %, in detecting soybean, corn, and sunflower seeds at simulated forward speeds of 6 and 12 km/h. The findings of this study contribute to the development of more efficient and accurate methods for testing and detecting the seeding performance of precision seeders. Using fiberglass as a plate material for piezoelectric impact sensors is a promising approach to improving seed detection accuracy and ensuring the quality of seeding operations. [ABSTRACT FROM AUTHOR]

This study investigates the dynamic characteristics of a smart PZT interface mounted on a prestressed anchorage to verify the numerical feasibility of the admittance-based anchor force monitoring technique. Firstly, the admittance-based anchor force monitoring technique through a single-mount PZT interface is outlined. The admittance response of the PZT interface-anchorage system is theoretically derived to show the proof-of-concept of the technique for anchor force monitoring. Secondly, a finite element model corresponding to a well-established experimental model in the literature is constructed. The effect of anchor force is equivalently treated by the contact stiffness and damping parameters at the bottom surface of the anchorage. Thirdly, the admittance and the impedance responses are numerically analyzed and compared with the experimental data to evaluate the accuracy of the numerical modelling technique. Fourthly, the local dynamics of the PZT interface are analyzed by modal analysis to determine vibration modes that are sensitive to the change in the contact stiffness (i.e., representing the anchor force). Finally, the admittance responses corresponding to the sensitive vibration modes are numerically analyzed under the change in the contact stiffness. The frequency shift and the admittance change are quantified by statistical damage indices to verify the numerical feasibility of the anchor force monitoring technique via the smart PZT interface. The study is expected to provide a reference numerical model for the design of the single-point mount PZT interface.

In this study, an acoustic emission (AE) sensor was fabricated using lead-free Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 (BZT–BCT) ceramics. The acoustic and electromechanical properties of the AE sensor were determined by the shapes of the piezoelectric ceramics. To optimize the AE sensor performance, the shapes of the ceramics were designed according to various diameter/thickness ratios (D/T) = 0.5, 1.0, 1.5, 2.0, 2.5, 3.0. The BZT–BCT ceramic with D/T = 1.0 exhibited excellent values of a piezoelectric charge coefficient (d33), piezoelectric voltage coefficient (g33), and electromechanical coupling factor (kp), which were 370 (pC/N), 11.3 (10−3 Vm/N), and 0.58, respectively. Optimum values of resonant frequency (fr) = 172.724 (kHz), anti-resonant frequency (fa) = 196.067 (kHz), and effective electromechanical coupling factor (keff) = 0.473 were obtained for the manufactured BZT–BCT ceramic with D/T = 1.0. The maximum sensitivity and frequency of the AE sensor made of the BZT–BCT ceramic with a D/T ratio of 1.0 were 65 dB and 30 kHz, respectively.

As a key load-bearing element in a prestressed structure, the anchor should be appropriately monitored to secure its as-built prestressing force. In previous studies, the impedance-based prestress force monitoring technique through a mountable lead–Zirconate–Titanate (PZT) interface was developed. However, the previous design of the PZT interface uses a two-point mount technique through two bonding layers, causing inconveniences during installation and replacement processes. To address this issue, we propose an alternative PZT interface model for prestress force monitoring based on the impedance method. The proposed model uses a single-point mounting technique that allows it to be more conveniently installed and replaced on a host structure. First, the electromechanical impedance of the proposed PZT interface is theoretically derived. The proof-of-concept of the proposed PZT interface for impedance monitoring is then shown by finite element modelling. Afterwards, a lab-scaled experiment is conducted on an anchoring system to demonstrate the practical application feasibility of the proposed technique. The obtained results show that the proposed technique can produce impedance responses that are highly sensitive to the prestress force. The performance of the proposed model for impedance-based prestress force monitoring is found to be comparable with the previous techniques (the washer-type mount and the two-point mount). Due to its advantage of simple design, the newly designed PZT interface is promising for the future development of the impedance-based anchor force monitoring systems in practice.

Space charges are one of the main challenges facing the constantly increasing use of extruded high voltage direct current (HVDC) cables. The Pulsed Electro-Acoustic (PEA) method is one of the most common procedures for space charge measurements of insulation. One issue with the PEA method is distortion due to the crosstalk between the applied voltage pulse and the acoustic sensor. This work analyzed two factors involved in the reduction in this distortion: the influence of the exposed semiconductor distance between the injection electrodes and PEA test cell, and the influence of adding a reactance at the grounding circuit of the PEA test cell. The interaction of these two factors with the distortion was analyzed through a series of experimental testing. Moreover, the performance regarding distortion after applying a developed coaxial injection was compared with the standard non-coaxial injection configuration. It was observed that these two factors had a direct impact on distortion and can be utilized for the reduction in distortion arising from the crosstalk of the applied pulsed voltage. The results can be utilized for the consideration of practical aspects during the construction of a PEA test setup for the measurement of full-size HVDC cables.

Piezoelectric materials have been used for decades in the field of sensors as transducers and energy harvesters. Among these, piezoelectric composites are emerging being extremely advantageous in terms of production, costs, and versatility. However, the piezoelectric performances of a composite with randomly dispersed filler are not comparable with bulk ferroelectric ceramics and electroactive polymers. In order to achieve highly performing and low-cost materials, this work aims to develop flexible composites made of Lead zirconate titanate (PZT) filler in Polydimethylsiloxane (PDMS) matrix, with a specific internal structure called quasi-1–3 connectivity. Such a structure, comprising particles arranged in columns along a preferred direction, is performed through dielectrophoresis by applying an alternating electric field on the composite before and during the polymerization. The developed flexible material could be introduced into complex structures in various application fields, as sensors for structural monitoring.

Due to the outstanding coupling between piezoelectric and semiconducting properties of zinc oxide nanowires, ZnO NW-based structures have been demonstrating promising potential with respect to their applicability in piezoelectric, piezotronic and piezo-phototronic devices. Particularly considering their biocompatibility and biosafety for applications regarding implantable medical detection, this paper proposed a new concept of piezoelectric composite, i.e., one consisting of vertically aligned ZnO NW arrays and an insulating polymer matrix. First, the finite element method (FEM) was employed to drive optimization strategies through adjustment of the key parameters such as Young’s modules and the dielectric constant of the dielectric constituents, together with the density and dimension of nanowire (NW) itself. Second, to investigate the functionality of each individual layer of composite, different designed structures were fabricated and characterized in terms of electrical and piezoelectric properties. Next, experimental and simulation tests were performed, indicating that the decreasing thickness of the top poly(methyl methacrylate) layer (PMMA) can substantially enhance the piezoelectric sensitivity of the ZnO NW composite. Besides the further benefit of no polarization being needed, our material has a comparable charge coefficient (d33) with respect to other lead-free alternatives (e.g., BaTiO3), confirming the high sensing abilities of the developed structure based on vertically aligned ZnO NW arrays. Finally, a time-varying model combining piezoelectricity and electric circuit modules was investigated in detail, giving rise to an estimation of the d33 coefficient for ZnO NWs. Based on this study, the developed material is revealed to be highly promising in medical applications, particularly regarding the FFR technique, where coronary pressure can be measured through a piezoelectric sensor.

Purpose. Investigations of the characteristics of pressure waves presuppose the registration of the total profile of the pressure wave at a given point in space. For these purposes, various types of «pressure to the electrical signal» transmitters (sensors) are used. Most of the common sensors are unsuitable for measuring the pulse pressure in a closed water volume at high hydrostatic pressures, in particular to study the effect of a powerful high-voltage pulse discharge on increasing the inflow of minerals and drinking water in wells. The purpose of the work was to develop antijamming piezoelectric waveguide sensor for measuring pulse pressure at a close distance from a high-voltage discharge channel in a closed volume of a liquid. Methodology. We have applied the calibration method as used as a secondary standard, the theory of electrical circuits. Results. We have selected the design and the circuit solution of the waveguide pressure sensor. We have developed a waveguide pulse-pressure sensor DTX-1 with a measuring loop. This sensor makes it possible to study the spectral characteristics of pressure waves of high-voltage pulse discharge in closed volumes of liquid at a hydrostatic pressure of up to 20 MPa and a temperature of up to 80 °C. The sensor can be used to study pressure waves with a maximum amplitude value of up to 150 MPa and duration of up to 80 µs. According to the results of the calibration, the sensitivity of the developed sensor DTX-1 with a measuring loop is 0.0346 V/MPa. Originality. We have further developed the theory of designing the waveguide piezoelectric pulse pressure sensors for measuring the pulse pressure at a close distance from a high-voltage discharge channel in a closed fluid volume by controlling the attenuation of the amplitude of the pressure signal. Practical value. We have developed, created, calibrated, used in scientific research waveguide pressure pulse sensors DTX-1. We propose sensors DTX-1 for sale in Ukraine and abroad. Sensors DTX-1 can be used to study pressure waves with a maximum amplitude value of up to 150 MPa in closed fluid volumes at a hydrostatic pressure of up to 20 MPa and a temperature of up to 80 °C.

The extensive use of reinforced materials in the construction industry has raised increased concerns about their safety and durability, while corrosion detection of steel materials is becoming increasingly important. For the scientific management, timely repair and health monitoring of construction materials, as well as to ensure construction safety and prevent accidents, this paper investigates corrosion detection on construction materials based on piezoelectric sensors. At present, the commonly used corrosion detection methods include physical and electrochemical methods, but there are shortcomings such as large equipment area, low detection frequency, and complex operation. In this study an improved piezoelectric ultrasonic sensor was designed, which could not only detect the internal defects of buildings while not causing structural damage, but also realize continuous detection and enable qualitative and quantitative assessment. Corrosion detection of reinforced building materials with piezoelectric sensors is quick and accurate, which can find hidden dangers and provide a reliable basis for the safety of the buildings.

Effectiveness of operation of a weapon stabilization system is largely dependent on the choice of a sensor, i.e. an accelerometer. The paper identifies and examines fundamental errors of piezoelectric accelerometers and offers measures for their reduction. Errors of a weapon stabilizer piezoelectric sensor have been calculated. The instrumental measurement error does not exceed 0.1 × 10−5 m/s2. The errors caused by the method of attachment to the base, different noise sources and zero point drift can be mitigated by the design features of piezoelectric sensors used in weapon stabilizers.

In overcoming the worldwide problem of overweight and obesity, automatic dietary monitoring (ADM) is introduced as support in dieting practises. ADM aims to automatically, continuously, and objectively measure dimensions of food intake in a free-living environment. This could simplify the food registration process, thereby overcoming frequent memory, underestimation, and overestimation problems. In this study, an eating event detection sensor system was developed comprising a smartwatch worn on the wrist containing an accelerometer and gyroscope for eating gesture detection, a piezoelectric sensor worn on the jaw for chewing detection, and a respiratory inductance plethysmographic sensor consisting of two belts worn around the chest and abdomen for food swallowing detection. These sensors were combined to determine to what extent a combination of sensors focusing on different steps of the dietary cycle can improve eating event classification results. Six subjects participated in an experiment in a controlled setting consisting of both eating and non-eating events. Features were computed for each sensing measure to train a support vector machine model. This resulted in F1-scores of 0.82 for eating gestures, 0.94 for chewing food, and 0.58 for swallowing food.

Water leakage is a significant issue in infrastructure, such as submarine tunnels, which can lead to major disasters and property losses. Therefore, it is of great significance to develop a water leakage detection sensor with simple preparation process, low cost, and small limitation of applicable location. In this study, a novel hybrid flexible piezoresistive/piezoelectric double-mode sensor with a sandpaper negative microstructure is proposed. A unique dual-path perception structure is designed that can simultaneously and independently detect two signals of water leakage frequency and water leakage volume. The piezoresistive layer is formed by polydimethylsiloxane (PDMS) coated with multiwalled carbon nanotubes (MWCNTs), which is molded by sandpaper molding. By sensing the deformation caused by the swelling of superabsorbent polymers (SAPs), the water leakage volume can be detected as low as 0.5 mL. The piezoelectric layer is a polyvinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE) film prepared by the spin-coating method, and the water leakage frequency (0.5-4 Hz) is detected by direct contact with water droplets. This work also studied the performance of the double-mode sensor under low temperature and seawater leakage conditions and further verified its reliability in different environments. The design of the new hybrid flexible piezoresistive/piezoelectric double-mode sensor provides a new possibility for water leakage monitoring, such as in submarine tunnels.

Zinc oxide (ZnO) nanowires (NWs) are excellent candidates for the fabrication of energy harvesters, mechanical sensors, and piezotronic and piezophototronic devices. In order to integrate ZnO NWs into flexible devices, low-temperature fabrication methods are required that do not damage the plastic substrate. To date, the deposition of patterned ceramic thin films on flexible substrates is a difficult task to perform under vacuum-free conditions. Printing methods to deposit functional thin films offer many advantages, such as a low cost, low temperature, high throughput, and patterning at the same stage of deposition. Among printing techniques, gravure-based techniques are among the most attractive due to their ability to produce high quality results at high speeds and perform deposition over a large area. In this paper, we explore gravure printing as a cost-effective high-quality method to deposit thin ZnO seed layers on flexible polymer substrates. For the first time, we show that by following a chemical bath deposition (CBD) process, ZnO nanowires may be grown over gravure-printed ZnO nanoparticle seed layers. Piezo-response force microscopy (PFM) reveals the presence of a homogeneous distribution of Zn-polar domains in the NWs, and, by use of the data, the piezoelectric coefficient is estimated to be close to 4 pm/V. The overall results demonstrate that gravure printing is an appropriate method to deposit seed layers at a low temperature and to undertake the direct fabrication of flexible piezoelectric transducers that are based on ZnO nanowires. This work opens the possibility of manufacturing completely vacuum-free solution-based flexible piezoelectric devices.

ZnO nanowires are excellent candidates for energy harvesters, mechanical sensors, piezotronic and piezophototronic devices. The key parameters governing the general performance of the integrated devices include the dimensions of the ZnO nanowires used, their doping level, and surface trap density. However, although the method used to grow these nanowires has a strong impact on these parameters, its influence on the performance of the devices has been neither elucidated nor optimized yet. In this paper, we implement numerical simulations based on the finite element method combining the mechanical, piezoelectric, and semiconducting characteristic of the devices to reveal the influence of the growth method of ZnO nanowires. The electrical response of vertically integrated piezoelectric nanogenerators (VING) based on ZnO nanowire arrays operating in compression mode is investigated in detail. The properties of ZnO nanowires grown by the most widely used methods are taken into account on the basis of a thorough and comprehensive analysis of the experimental data found in the literature. Our results show that the performance of VING devices should be drastically affected by growth method. Important optimization guidelines are found. In particular, the optimal nanowire radius that would lead to best device performance is deduced for each growth method.