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Flexible high-performance piezoelectric nanogenerator (PENG) excel in converting mechanical energy into electrical energy and exhibit remarkable sensitivity, a feature that is paramount for the development of self-driven piezoelectric sensors. In this study, electrospinning technology was used to prepare poly (vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)] based piezoelectric nanofiber composite films containing potassium-sodium niobate nano particles (KNN NPs) and Nb 2 CT x co-doping, as well as single-component doping. The co-doped composite film attained an optimal β-phase content of 91.33%. Owing to the enhanced dipole alignment and interface charge polarization, the piezoelectric performance of the co-doped composite film was significantly enhanced compared to that of single-component doping. The co-doped piezoelectric composite film displayed a stable maximum output voltage of 20 V and an output current of 1.46 μA. The peak instantaneous power output was measured at 9.9 μW under the optimal resistive load of 10 MΩ. Durability testing over 2000 cycles affirmed the excellent mechanical stability of the piezoelectric composite film. Moreover, the fabricated piezoelectric composite film showed considerable potential in applications such as monitoring human activities and serving as an early warning system for natural disasters such as landslides, as indicated by the test results. [ABSTRACT FROM AUTHOR]

Ballistocardiography (BCG) studies ballistic forces on the body generated during a heartbeat. As it is an unobtrusive detection method, that requires sensors measuring small dynamic forces. Piezoelectric sensors are ideal, but improvements in sensitivity are needed. Here, a universal method is demonstrated to obtain enhanced effective transverse charge constants by utilizing thin and long sensors fabricated upon compliant substrates. This approach is validated using the uniquely printable and patternable piezoelectric polymer, poly(vinylidene fluoride‐co‐trifluoroethylene) (P(VDF‐TrFE). Discrete sensors detect displacements of less than 1 µm, dynamic forces of ∼mN, and accelerations of ≈1 mm−1 s2. Since the sensor is screen‐printable, it is upscaled to a human‐sized array (60 × 90 cm, 255 sensors). High quality spatially resolved BCG measurements of a person is demonstrated in seated and supine positions. The obtained heart rate is verified using photoplethysmography. This development opens the door to ever‐more sensitive piezoelectric sensors, crucial for applications including and beyond healthcare. [ABSTRACT FROM AUTHOR]

In marine scientific research, ocean monitoring is crucial where the batterypowered sensor devices are placed under the water to collect different information like temperature, pressure, and turbidity in underwater sensor networks (UWSNs). Thus, keeping these devices active for longer periods is challenging. In the last decades, the piezoelectric transducer (PZT) material has been used widely for constructing more environmentally friendly energy harvesting systems. The PZT harvester offers a promising solution by eliminating the need for batteries for running devices in the future with less maintenance. The PZT harvester allows the system to generate higher voltage to run low-power devices. This paper designed and developed a new renewable energy harvester system using PZT transducers for running different types of underwater sensor devices like temperature, turbidity, and obstacle sensors. The proposed PZT-based energy harvester employs a twostage amplification model for generating higher voltage and current to run multiple devices. The sensing information collected from these sensors is transmitted to the cloud which is later utilized for analysis and decisionmaking. Experiment results show the proposed PZT-based energy harvester can generate a voltage of 13 volts (V) and a current of 43.3 milliampere (mA) equivalent to 562 milliwatt (mW) which is very good to run multiple low-power underwater sensor devices. [ABSTRACT FROM AUTHOR]

Assessing the vibration signature produced by a rotating component of the wind turbine enables the identification of operational conditions and the detection of potential faults at an early stage. The main purpose is to enhance the sustainability of wind turbines while increasing the lifespan and uptime of their operational systems. This vibration analysis is based on the processing of the signal provided by sensors, which often incorporates piezoelectric transducers. This paper evaluates the consequences of employing piezoelectric sensors used for vibration measurement on electrical machines integrated into wind turbines by conducting a life cycle assessment (LCA). The widespread use of piezoelectric materials is due to their high sensitivity to vibrations, although their selection is also influenced by regulatory restrictions. This research focuses on the environmental impact of piezoelectric accelerometers used commonly in condition monitoring systems. The collected literature data on the manufacturing processes are inputted into the LCA model which is powered by the Ecoinvent 3 database. The impact assessment is carried out using the European ILCD 2011 Midpoint+ method by calculating the unique scores of the selected impact categories. The results are presented and discussed in terms of environmental indicators, as well as ecological recommendations on the design. [ABSTRACT FROM AUTHOR]

Advancements in operando techniques have unraveled the complexities of the Electrode Electrolyte Interface (EEI) in electrochemical energy storage devices. However, each technique has inherent limitations, often necessitating adjustments to experimental conditions, which may compromise accuracy. To address this challenge, a novel battery cell design is introduced, integrating piezoelectric sensors with electrochemical analysis for surface‐sensitive operando measurements. This innovative approach aims to overcome conventional limitations by accommodating commercial‐grade battery electrodes within a single body, alongside a piezoelectric sensor. This enables operando electrogravimetric measurements to be realized, and the electrochemistry of a battery to be more faithfully reproduced at the sensor level. A proof of concept is carried out on both Li‐ion (LiFePO4//Graphite) and Na‐ion (Na3V2(PO4)2F3//Hard carbon) systems, utilizing commercially available powder electrodes. In both cases, the results reveal rational mass variations at the sensor level during the cycling of commercial electrodes with mass loadings several orders of magnitude higher, while performing Galvanostatic Charge Discharge (GCD) tests across various C‐rates. This innovative design opens up possibilities for a broader application of operando electrogravimetry within the battery community, to enhance the understanding of EEI behavior and facilitate the development of more efficient energy storage solutions. [ABSTRACT FROM AUTHOR]

Ensuring the safety of infants around swimming pools or hazardous areas can be tasking for caregivers and their parents. Providing safety devices that can keep track of infants and prevent them from going to unauthorized locations is very necessary. The study aims to design and implement an infant safety system that uses a Piezoelectric sensor. The paper constructed a system to alert parents of an infant's attempted entry into a dangerous area, such as balconies and swimming pools, and it also incorporated an automatic door-locking system around the location. The Piezoelectric Sensor Infant Monitoring System was designed to enhance infant safety at home. The system utilized piezoelectric transducers and pressure sensors, incorporating an automatic door to secure unauthorized zones. Components like Arduino Nano, an LCD, and a buzzer were used to create the prototype. The device was designed to harvest energy by converting mechanical energy from ambient vibrations into electrical energy that will send signals to the GSM module, alerting the homeowner by sending a call. The model adopts the technology of pressure control, and when the pressure reaches a set value and the dial of the scale reaches a specific value simultaneously, the automatic door will open. The device is designed to harvest energy by converting mechanical energy from ambient vibrations into electrical energy that will power the motor of the automatic door of the safety system. The test proved the system's effectiveness in accurately detecting and blocking an infant, but it only grants access to authorized individuals while alerting caregivers. The results demonstrated improved child safety, responsible parenting, and a secure environment. The Piezoelectric sensor safety system offers a practical solution for enhancing infant monitoring for safety and preventing avoidable mishaps, thereby reducing infant mortality and morbidity in present times. The system can serve as a protection device for very busy mothers. [ABSTRACT FROM AUTHOR]

In order to provide a scientific reference and basis for exploring and enhancing the fabrication process of ZnO piezoelectric thin films, nanoscale ZnO piezoelectric coatings with strong adhesion were deposited on stainless steel substrates using the pulsed arc ion plating method. The effects of two critical fabrication process parameters, namely working gas pressure and target-to-substrate distance, on the crystal structure and electrical resistance properties of the ZnO piezoelectric sensor coatings were systematically studied. Results showed that a reduction in working gas pressure led to an improvement in the crystallinity of the coatings. As target-to-substrate distance increased, the crystallinity first increased and then decreased, resulting in a decrease in resistance. These findings provided a scientific reference and basis for the application of new permanent thin-film pressure sensors(PMTS) in the pressure monitoring of high and ultra-high-voltage smart casings.

Aircraft structures are exposed to a variety of operational and environmental loads that can cause structural deformation and fractures. Structural Health Monitoring (SHM) has emerged as a promising solution for in-situ monitoring of structural components. This article presents a state-of-the-art review of SHM in aviation, current regulations, data acquisition sensors and equipment, and damage detection and identification methods. The article discusses in detail the regulations SHM specific to both civil and military aviation. A comprehensive review of conventional electrical resistance sensors, fiber optic, piezoelectric sensors and smart materials used for SHM monitoring in aircraft structures is then presented. The pros and cons of each data acquisition approach were discussed individually. The damage detection and identification section begins by describing the traditional knowledge-based methods that are combined with expert knowledge and theory, then focuses on the applicability in aircraft SHM systems of spectral or frequency domain models. The last part investigates the new paradigm, machine learning and deep learning methods such as CNN and LSTM on different types of aircraft structures through the existing literature. Furthermore, it covers an emerging approach called physics-informed neural networks (PINN), which combines physics and machine learning, and explore its potential for SHM applications. [ABSTRACT FROM AUTHOR]

It is demonstrated that the application of piezoelectric sensors to metallic bars and strands can enable determining the status of the integrity of these elements through the spectrum of their acoustic excitations. The voltage output of the piezo, secured to metal bars or strands, is fed to the input of a Fast Fourier Transform analyzer, which allows displaying the spectrum of the excitations from which information on the length, overall quality of the metal, and the presence of defects can be obtained. We show that the analysis, performed on several materials and strands of different lengths, could be useful for cases in which visible inspection and/or direct access to the entire body of the metallic elements is not possible. Applications of our study for testing metallic structures embedded in concrete foundations are reported for construction sites. [ABSTRACT FROM AUTHOR]

Nanotubes with multi-walled structures have the ability of changing the characterization of poly (Silicone Rubber) nanocomposites. In this way, silicone rubber/multiwalled carbon nanotubes (SR/MWCNTs) nanocomposite is achieved by reaction with multifunctional. A new design of SR/MWCNT nanocomposites was developed as a result of experiments to clarify the advantages of filling the MWCNTs with different patterns within the dielectrics. As part of this work, silicone rubber/multiwalled carbon nanotube nanocomposites and room temperature vulcanization (RTV) methods were used to fabricate piezoelectric sensors. The analysis of the frequency response of SR/MWCNT nanocomposites has been conducted under variable thermal conditions (20–40°C). This study succeeded in applying poly (Silicon Rubber) nanocomposites as piezoelectric sensors by exhibiting new electrical characteristics (resistance, capacitance, real and imaginary impedance) under various thermal conditions based on certain types and concentrations of MWCNTs. [ABSTRACT FROM AUTHOR]

Flexible piezoelectric sensors combine advantages including low‐cost, flexibility, multi‐functions, present a huge market prospect. In this research, multiwalled carbon nanotubes (MWCNT)/MXene/polyacrylonitrile (PAN) piezoelectric composites films for flexible piezoelectric sensors are fabricated by electrospinning technology, the planar zigzag conformation content of 97.98% in PAN composite fibers is achieved owing to the synergistic effect of MWCNT and MXene, the synergistic effect of MWCNT and MXene nanoparticles can also efficiently promote the mechanical performance and piezoelectric output. The piezoelectric sensor exhibits fast response time (10.21 ms), a possible mechanism is proposed to explain the improvement of piezoelectric effect. The sensor can measure human pulse, distinguish human movements, the fabricated sensor has broad practical value in the field of healthcare, its' use can contribute to stable and accurate measurements of physiological parameters, enabling applications in various healthcare and fitness monitoring scenarios. [ABSTRACT FROM AUTHOR]

Numerous research studies have emphasized the significance of accurately detecting head impacts and implementing safety measures. This study addresses this crucial need by utilizing machine learning algorithms applied to data from piezoelectric sensors on a simulated head model. Employing a systematic approach, this work utilizes Random Forest (RF) and Extreme Gradient Boosting (XGBoost) models to process the normalized sensor data, aiming to pinpoint impact locations with high precision. Through rigorous k-fold cross-validation and comprehensive performance analysis, the study reveals that the XGBoost model slightly outperforms the RF model, achieving an RMSE of 0.4764 and an R^2 of 0.9485. Feature importance evaluations suggest an optimal sensor placement strategy, potentially reducing the model complexity while retaining predictive accuracy. The superior performance of the XGBoost model, combined with strategic sensor placement, highlights the study’s contribution to enhancing head impact safety measures in sports and industrial settings. The findings pave the way for future research into the deployment of intelligent safety systems, leveraging the synergy between wearable technology and machine learning.

This paper presents a new approach to monitoring ultrasonic systems using structurally integrated piezoceramics. These are integrated into the sonotrode at different points and with different orientations. The procedure for integrating the piezoceramics into the sonotrode and their performance is experimentally investigated. We examine whether the measured signal can be used to determine the optimal operating frequency of the ultrasonic system, if integrating several piezoceramics enables discernment of the current vibration shape, and if the piezoceramics can withstand the high strains caused by the vibrations in a frequency range of approximately 20–25 kHz. The signals from the piezoceramic sensors are compared to the real-time displacement at different points of the sonotrode using a 3D laser scanning vibrometer. To evaluate the performance of the sensors, different kinds of excitation of the ultrasonic system are chosen. [ABSTRACT FROM AUTHOR]

The successful fabrication and application of 3D‐printed piezoelectric sensors, made from polyvinylidene fluoride‐barium titanate nanocomposites, for continuous blood pressure (BP) monitoring, is presented. The sensors are fabricated using direct‐ink write 3D printing technique possessing excellent flexibility, rendering them ideal for wearable applications. Key printing parameters, such as nozzle size and pressure, are optimized to achieve a β‐phase of 70% and an overall crystallinity of 48.3%. The sensors are characterized under dynamic pressures and show excellent linearity with a coefficient of determination (R2) of 0.99 and a pressure sensitivity of 0.024 V kPa−1, and demonstrate durability over 3600 cycles. The performance of our piezoelectric sensors is compared with a standard BP monitoring device for a subject, and a strong correlation with a standard deviation of 3.87 and 0.63 mmHg for sytolic BP and diastolic BP, respectively, is found. The development of sensors through 3D printing, as demonstrated in this study, represents a significant scientific advancement in the field of personalized healthcare. This novel approach enables the creation of customized wearable devices tailored for real‐time health monitoring of BP and heart rate. [ABSTRACT FROM AUTHOR]

The piezocomposites from poly-(vinylidene fluoride) (PVDF) with BaTiO3 (BT) are largely presented in literature, but the composites from polydimethylsiloxane (PDMS) with BT consist a very new scientific preoccupation. The novelty of the paper lies in a new simpler route of preparation of the two composites with PDMS and respectively PVDF matrix, with tailored deposition on specific substrates for microelectronic use (e.g. indium-tin-oxide ITO/glass, Si/Pt, polyethylene terephthalate PET), along with an extensive comparation of their dielectric features, a consistent comparison of the influence of polymer matrix upon the piezoelectric features, and a demonstration of direct use for microelectronic applications of the composites of BT with PDMS. An interesting effect is observed around 100 kHz domain, determined by the activity and architecture of BT particles mainly for the BTPDMS composites, which induce an additional ionic-dipolar conjugated polarization, as a displacement due to the balance between the resonance and anti-resonance frequency. Such phenomena explain the potential use of such composites as resonators/filters, and BT-PDMS composites should be further investigated for tailored applications in radiofrequency electronic field. We can appreciate that superior piezoelectric features are offered by the composites of BT with PDMS, comparing to the composites with PVDF, which means that the composites of BT with PDMS were worth to study, leading to more versatile variants of electronic characteristics and with superior values. [ABSTRACT FROM AUTHOR]

Multiwall carbon nanotubes (MWCNTs) have the potential to change electrical, optical, and rheological properties of traditional polymers applications. This paper describes optical characterization of SRMWCNT nanostructures for emerging piezoelectric sensors. SEM images were used to characterize the dispersion of MWCNTs inside the rubber silicone. Under various wavelengths, novel SR/MWCNT nanocomposites materials have been characterized using FTIR spectra analysis and UV-2300 double beam spectrophotometer. A new design of SR/MWCNT nanocomposites has also been experimentally investigated for the effect of multiwalled carbon nanotubes on extinction coefficient and kinetic energy. As results of measurements, MWCNTs enhanced the absorbance and reflectance of silicon rubber sensors in piezoelectric applications over the whole wavelength range. In this study, MWCNT has been successfully used to control optical parameters up to 25 % in virgin piezoelectric sensors and about 30 % in long-run operation. Finally, it has been presented a comparative study of optical properties, energy functions, coefficients, and indices of conventional silicon rubber and SR/MWCNT nanocomposites.

Assessing the vibration signature produced by a rotating component of the wind turbine enables the identification of operational conditions and the detection of potential faults at an early stage. The main purpose is to enhance the sustainability of wind turbines while increasing the lifespan and uptime of their operational systems. This vibration analysis is based on the processing of the signal provided by sensors, which often incorporates piezoelectric transducers. This paper evaluates the consequences of employing piezoelectric sensors used for vibration measurement on electrical machines integrated into wind turbines by conducting a life cycle assessment (LCA). The widespread use of piezoelectric materials is due to their high sensitivity to vibrations, although their selection is also influenced by regulatory restrictions. This research focuses on the environmental impact of piezoelectric accelerometers used commonly in condition monitoring systems. The collected literature data on the manufacturing processes are inputted into the LCA model which is powered by the Ecoinvent 3 database. The impact assessment is carried out using the European ILCD 2011 Midpoint+ method by calculating the unique scores of the selected impact categories. The results are presented and discussed in terms of environmental indicators, as well as ecological recommendations on the design.

In this study, a zinc oxide (ZnO)‐decorated nickel microfiber (ZNMF)‐based piezoelectric nanogenerator (ZNMF‐PENG) using electrospinning, metal electroplating, electrospraying, and ceramic growing techniques is fabricated. The combination of these techniques enables the ZNMF‐PENG to possess high transparency and flexibility that are difficult to achieve through the existing piezoceramic‐based PENGs. In particular, the presence of innumerable piezoceramic ZnO nanowires inside the ZNMF‐PENG allows for detecting microbubble movements having an extremely low buoyancy force of 0.009 N, which is beneficial for detecting cavitation. Moreover, in comparison to previously reported PENGs fabricated using an electrospinning technique, the ZNMF‐PENG demonstrates the highest energy‐harvesting efficiency of 8750 V N−1 m−2. The novel approach in materials and methods proposed in this study is expected to contribute to the further advancement in developing transparent, flexible, and performance‐improved PENGs applicable to various industrial applications. [ABSTRACT FROM AUTHOR]

Structural Health Monitoring (SHM) techniques, such as Electromechanical Impedance Spectroscopy (EMIS), aim to continuously monitor structures for defects, thus avoiding the need for regular maintenance. While attention has been given to the application of EMIS in the automatic detection of damage in metallic and composite components, integrity monitoring of structural adhesive joints has been comparatively neglected. This paper investigated the use of damage metrics with electrical impedance measurements to detect defects in Single-Lap Joints (SLJs) bonded with a modified epoxy adhesive. Traditional metrics using statistical and distance-based concepts, such as the Root-Mean-Squared Deviation, R M S D , or the Correlation Coefficient, C C , are addressed at detecting voids in the adhesive layer and are applied to five different spectral frequency ranges. Furthermore, new damage metrics have been developed, such as the Average Canberra Distance, A C D , which enables a reduction of possible outliers in damage detection, or the complex Root-Mean-Squared Deviation, c R M S D , which allows for the use of both the real and imaginary components of the impedance, enabling better damage detection in structural adhesive joints. Overall, damage detection is achieved, and for certain spectral conditions, differentiation between certain damage sizes, using specific metrics, such as the R M S D or c R M S D , may be possible. Overall, the R M S D or c R M S D values from damaged SLJs tend to be double the metric values from undamaged joints. [ABSTRACT FROM AUTHOR]

Herein, the density functional theory is used to study the structural, mechanical, electrical, optical, and hydrogen evolution reaction (HER) properties of monolayer structures (α,β)–S2C2N2$\left(\right. \alpha , \beta \left.\right) – \left(\text{S}\right)_{2} \left(\text{C}\right)_{2} \left(\text{N}\right)_{2}$ and (α,β)–SCN/CN$\left(\right. \alpha , \beta \left.\right) – \text{SCN} / \text{CN}$. They are claimed to be stable monolayer structures by phonon dispersion and ab initio molecular dynamics (AIMD). Compared to graphene (≈340 N m−1), the (α,β)–SCN/CN$\left(\right. \alpha , \beta \left.\right) – \text{SCN} / \text{CN}$ shows a higher Young's modulus (≈429, 414 N m−1). Moreover, the piezoelectric stress coefficient of α‐SCN/CN$\text{SCN} / \text{CN}$ (d11$d_{11}$=2.65 pm V−1) is comparable with bulk piezoelectric α‐quartz (d11$d_{11}$=2.3 pm V−1). Exciton effect at M point causes redshift and enhancement of light absorption of α‐SCN/CN$\text{SCN} / \text{CN}$ and β–SCN/CN$\beta – \text{SCN} / \text{CN}$. The overpotential of β–SCN/CN$\beta – \text{SCN} / \text{CN}$ is only –0.072 V. Besides, the (α,β)–SCN/CN$\left(\right. \alpha , \beta \left.\right) – \text{SCN} / \text{CN}$ gives a small effective electron mass of about 0.2(m0). It is worth mentioning that the monolayer structures (α,β)–S2C2N2$\left(\right. \alpha , \beta \left.\right) – \left(\text{S}\right)_{2} \left(\text{C}\right)_{2} \left(\text{N}\right)_{2}$ show the semimetal phases. Due to the unique semimetal phase, the absorption of β–S2C2N2$\beta – \left(\text{S}\right)_{2} \left(\text{C}\right)_{2} \left(\text{N}\right)_{2}$ has an excellent performance in the near‐infrared (NIR) region. It can be enhanced at the NIR region and extended to the middle infrared region when applying tensile stress. These results provide more choices for 2D materials in electrocatalysis, piezoelectric sensors, visible light devices, and infrared photodetectors. [ABSTRACT FROM AUTHOR]

With the advent of the intelligence era, flexible piezoelectric tactile sensors are the key components for sensing information and sending signals. The performance parameters of piezoelectric sensors are closely related to the selection of piezoelectric materials. Compared with conventional piezoelectric materials, polyvinylidene fluoride (PVDF) has significant advantages in flexibility, stretchability, chemical stability, electromechanical conversion, ease of use, and acoustic propagation impedance. As a result, PVDF has become a popular topic of research. This paper introduces the working principle of piezoelectric materials and flexible piezoelectric sensors based on PVDF materials and details the research progress of different materials based on PVDF for the preparation of flexible piezoelectric tactile sensors, such as: PVDF and its copolymers for the preparation of flexible piezoelectric sensors and PVDF doped with other functional materials for the preparation of flexible piezoelectric sensors. In this paper, the advantages and disadvantages of different materials and the development prospects of PVDF flexible piezoelectric sensors are summarized to provide some insights for high‐performance flexible PVDF piezoelectric sensors. [ABSTRACT FROM AUTHOR]

Underwater sensor networks (UWSNs) are an emerging field in the research area as they have potential applications starting from pollution monitoring to defense and ocean exploration. Ocean monitoring is of great importance in marine scientific research. However, battery-operated devices utilized in such systems have limited power and maintenance is difficult. So, devices used underwater suffer from many research challenges and energy issues. Apart from all the problems, harvesting energy underwater is the main limiting factor. Nonrenewable energies come from sources that may not be replenished in our lifetime. Hence, it is very much essential to use renewable energy sources. Ocean has an unlimited amount of energy like wind energy, solar power, and tidal energy. Obtaining sufficient energy is sort of difficult since devices are underwater. Researchers are continuously working on it. Water energy is quite environmentally friendly, and it is a sustainable solution for a secure energy system. This paper implements a renewable energy system using piezoelectric (PZT) sensor, which generates sufficient power for lowpower underwater devices by employing two stage amplifier circuits. Experimental outcome shows the proposed energy harvesting system can generate a maximum voltage of 10.6 V and current of 10.1 mA which is sufficient to run low power underwater device. [ABSTRACT FROM AUTHOR]

Zinc oxide nanoparticles, especially those with a high aspect ratio (i. e., nanorods and nanowires), are of great interest for many applications as they are piezoelectric, photocatalytic and antimicrobial. In the present study, a plasma flight-thru synthesis method was developed that allows controlling the particle size and shape of the zinc oxide nanoparticles. In a direct current thermal plasma reactor operated at atmospheric pressure, zinc powder injected into the plasma jet was molten, vaporized and oxidized, which allowed growing zinc oxide nanoparticles. The particle spectrum ranged from small nanospheres to nanorods, nanowires and multipodic nanoparticles such as tetrapods. The influence of the oxygen rate and the plasma power (correlated to the discharge current) on the particle morphology was studied, and the feasibility of the nanowire-like particles as piezoelectric sensor material was investigated. Piezoelectric test sensors, equipped with the plasma-synthesized zinc oxide nanowires, successfully responded to mechanical stimulation after poling. [ABSTRACT FROM AUTHOR]

It is demonstrated that the application of piezoelectric sensors to metallic bars and strands can enable determining the status of the integrity of these elements through the spectrum of their acoustic excitations. The voltage output of the piezo, secured to metal bars or strands, is fed to the input of a Fast Fourier Transform analyzer, which allows displaying the spectrum of the excitations from which information on the length, overall quality of the metal, and the presence of defects can be obtained. We show that the analysis, performed on several materials and strands of different lengths, could be useful for cases in which visible inspection and/or direct access to the entire body of the metallic elements is not possible. Applications of our study for testing metallic structures embedded in concrete foundations are reported for construction sites.

Background: Head impacts in sports can produce brain injuries. The accurate quantification of head kinematics through instrumented mouthguards (iMG) can help identify underlying brain motion during injurious impacts. The aim of the current study is to assess the validity of an iMG across a large range of linear and rotational accelerations to allow for on-field head impact monitoring. Methods: Drop tests of an instrumented helmeted anthropometric testing device (ATD) were performed across a range of impact magnitudes and locations, with iMG measures collected concurrently. ATD and iMG kinematics were also fed forward to high-fidelity brain models to predict maximal principal strain. Results: The impacts produced a wide range of head kinematics (16–171 g, 1330–10,164 rad/s2 and 11.3–41.5 rad/s) and durations (6–18 ms), representing impacts in rugby and boxing. Comparison of the peak values across ATD and iMG indicated high levels of agreement, with a total concordance correlation coefficient of 0.97 for peak impact kinematics and 0.97 for predicted brain strain. We also found good agreement between iMG and ATD measured time-series kinematic data, with the highest normalized root mean squared error for rotational velocity (5.47 ± 2.61%) and the lowest for rotational acceleration (1.24 ± 0.86%). Our results confirm that the iMG can reliably measure laboratory-based head kinematics under a large range of accelerations and is suitable for future on-field validity assessments. [ABSTRACT FROM AUTHOR]

Statistical based reconstruction methods and signal processing tooling techniques are implemented and used to detect delaminations or debondings within composite complex items with very high precision. From the literature, it appears that although a single procedure for the estimation of structural health is a fast solution, multiple analyses based on different reconstruction methods or different damage parameters are the way to achieve maturation assessments of the methodology. This highlights the fact that the hardware and software parts of an SHM system need two different assessment and maturation ways. This work focuses on the software part by proposing a way to start assessing the outcomes. In this paper, the damage detection and localization strategy in CFRP plate-like structures with elastic guided waves excited and acquired with a circular array PWAS network is considered. Previous outcomes are compared by new analyses using a new post-processing approach based on a cross-correlation-based technique in terms of the BVID (Barely Visible Impact Damage) surface position and its center of mass. The advantage of this specific study is hopefully to enable confidence in the transition from R&D to field implementation. In addition, this work tries to evidence an improvement in terms of cost efficiency and reduced complexity while maintaining the same accuracy. [ABSTRACT FROM AUTHOR]

Monitoring the dressing operation of grinding wheels is crucial for optimizing the grinding process and ensuring quality outcomes. This study presents a novel data-driven method utilizing piezoelectric diaphragm signals, combined with the root mean square deviation index (RMSD) and power spectral density (PSD), to determine the optimal moment for interrupting the dressing operation of conventional aluminum oxide grinding wheels. By addressing the existing gaps in transition methods between dressed and undressed grinding wheels, as well as exploring untested metrics in digital signal processing, this research expands the use of alternative piezoelectric transducers for monitoring dressing. The proposed methodology utilizes a commercial acoustic emission (AE) sensor as a reference and employs experimental dressing tests to validate its effectiveness. The signals from both the AE sensor and the piezoelectric diaphragm are collected and subjected to digital processing to extract relevant features based on the proposed approach. Results demonstrate that the RMSD index successfully extracts information about the cutting surface conditions of the grinding wheel from signals obtained by both AE sensors and piezoelectric diaphragms. Furthermore, by selecting frequency bands that exhibit strong correlations with the grinding wheel's cutting surface conditions, a threshold is defined, enabling timely interruption of the dressing operation, thereby ensuring the restoration of the grinding wheel for continued use in grinding applications. Ultimately, this study showcases the feasibility of a non-invasive method for monitoring the dressing operation of conventional grinding wheels, contributing significantly to the optimization of the grinding process. [ABSTRACT FROM AUTHOR]

According to the 2018 National Immunization Survey conducted by the Center for Disease Control and Prevention (CDC), 83.9% of the breastfeeding mothers in the United States have used a breast pump at least once. However, the majority of existing products use a vacuum-only mechanism to extract milk. This causes common breast injuries such as nipple soreness, breast-tissue damage, and lactation complications after pumping. The objective of this work was to develop a bio-inspired breast pump prototype, named as SmartLac8, that can mimic infant suckling patterns. The input vacuum pressure pattern and compression forces are inspired from term infants' natural oral suckling dynamics captured in prior clinical experiments. Open-loop input–output data are used to perform system identification for two different pumping stages that facilitates controller design for closed-loop stability and control. A physical breast pump prototype with soft pneumatic actuators and custom piezoelectric sensors was successfully developed, calibrated, and tested in dry lab experiments. Compression and vacuum pressure dynamics were successfully coordinated to mimic the infant's feeding mechanism. Experimental data on sucking frequency and pressure on the breast phantom were consistent with clinical findings. [ABSTRACT FROM AUTHOR]

In Structural Health Monitoring (SHM) applications, the Direction of Arrival (DoA) estimation of Guided Waves (GW) on sensor arrays is often used as a fundamental means to locate Acoustic Sources (AS) generated by damages growth or undesired impacts in thin-wall structures (e.g., plates or shells). In this paper, we consider the problem of designing the arrangement and shape of piezo-sensors in planar clusters in order to optimize the DoA estimation performance in noise-affected measurements. We assume that: (i) the wave propagation velocity is unknown, (ii) the DoA is estimated via the time delays of wavefronts between sensors, and (iii) the maximum value of the time delays is limited. The optimality criterion is derived basing on the Theory of Measurements. The sensor array design is so that the DoA variance is minimized in an average sense by exploiting the Calculus of Variations. In this way, considering a three-sensor cluster and a monitored angles sector of 90°, the optimal time delays–DoA relations are derived. A suitable re-shaping procedure is used to impose such relations and, at the same time, to induce the same spatial filtering effect between sensors so that the sensor acquired signals are equal except for a time-shift. In order to achieve the last aim, the sensors shape is realized by exploiting a technique called Error Diffusion, which is able to emulate piezo-load functions with continuously modulated values. In this way, the Shaped Sensors Optimal Cluster (SS-OC) is derived. A numerical assessment via Green's functions simulations shows improved performance in DoA estimation by means of the SS-OC when compared to clusters realized with conventional piezo-disk transducers. [ABSTRACT FROM AUTHOR]

This study looks at the synthesis of innovative PEO/PVA/SrTiO3/NiO nanocomposites for piezoelectric sensors and gamma shielding applications that are low weight, elastic, affordable and have good gamma ray attenuation coefficients. The impact of SrTiO3/NiO on the structural characteristics of the PEO/PVA mixture is investigated. The polymer mixture PEO/PVA received additions of SrTiO3/NiO at concentrations of (0, 1, 2, 3 and 4) weight percent by the casting method. On the top surface of the films PEO/PVA/SrTiO3/NiO NCs, scanning electron microscopy reveals several randomly distributed aggregates or fragments that are consistent and coherent. An optical microscope image collection reveals that the blend*s additive distribution of NPs was homogenous. Gamma ray shielding application results show that the attenuation coefficient of PVA/PEO/SrTiO3/NiO NCs is increased by increasing concentration of SrTiO3/NiO nanoparticles. Radiation protection is another application for it. The pressure sensor application findings of NCs show that, when the applied pressure rises, electrical capacitance (Cp) increase.

Extreme environments are often faced in energy, transportation, aerospace, and defense applications and pose a technical challenge in sensing. Piezoelectric sensor based on single‐crystalline AlN transducers is developed to address this challenge. The pressure sensor shows high sensitivities of 0.4–0.5 mV per psi up to 900 °C and output voltages from 73.3 to 143.2 mV for input gas pressure range of 50 to 200 psi at 800 °C. The sensitivity and output voltage also exhibit the dependence on temperature due to two origins. A decrease in elastic modulus (Young's modulus) of the diaphragm slightly enhances the sensitivity and the generation of free carriers degrades the voltage output beyond 800 °C, which also matches with theoretical estimation. The performance characteristics of the sensor are also compared with polycrystalline AlN and single‐crystalline GaN thin films to investigate the importance of single crystallinity on the piezoelectric effect and bandgap energy‐related free carrier generation in piezoelectric devices for high‐temperature operation. The operation of the sensor at 900 °C is amongst the highest for pressure sensors and the inherent properties of AlN including chemical and thermal stability and radiation resistance indicate this approach offers a new solution for sensing in extreme environments. [ABSTRACT FROM AUTHOR]

This study looks at the synthesis of innovative PEO/PVA/SrTiO3/NiO nanocomposites for piezoelectric sensors and gamma shielding applications that are low weight, elastic, affordable and have good gamma ray attenuation coefficients. The impact of SrTiO3/NiO on the structural characteristics of the PEO/PVA mixture is investigated. The polymer mixture PEO/PVA received additions of SrTiO3/NiO at concentrations of (0, 1, 2, 3 and 4) weight percent by the casting method. On the top surface of the films PEO/PVA/SrTiO3/NiO NCs, scanning electron microscopy reveals several randomly distributed aggregates or fragments that are consistent and coherent. An optical microscope image collection reveals that the blend's additive distribution of NPs was homogenous. Gamma ray shielding application results show that the attenuation coefficient of PVA/PEO/SrTiO3/NiO NCs is increased by increasing concentration of SrTiO3/NiO nanoparticles. Radiation protection is another application for it. The pressure sensor application findings of NCs show that, when the applied pressure rises, electrical capacitance (Cp) increase. [ABSTRACT FROM AUTHOR]

This paper presents a new approach to monitoring ultrasonic systems using structurally integrated piezoceramics. These are integrated into the sonotrode at different points and with different orientations. The procedure for integrating the piezoceramics into the sonotrode and their performance is experimentally investigated. We examine whether the measured signal can be used to determine the optimal operating frequency of the ultrasonic system, if integrating several piezoceramics enables discernment of the current vibration shape, and if the piezoceramics can withstand the high strains caused by the vibrations in a frequency range of approximately 20–25 kHz. The signals from the piezoceramic sensors are compared to the real-time displacement at different points of the sonotrode using a 3D laser scanning vibrometer. To evaluate the performance of the sensors, different kinds of excitation of the ultrasonic system are chosen.

With the fast growth of wireless communications between nodes and sensor units and the increase of devices installed in remote places, and the development of IIoT applications, new requirements for power energy supply are needed to assure device functionality and data communication capabilities during extended periods of time. For these applications, energy harvesting takes place as a good solution to increase the autonomy of remote measuring solutions, since the usage of conventional power supply solutions has clear limitations in terms of equipment access and increased maintenance costs. In this context, regenerative energy sources such as thermoelectric, magnetic and piezoelectric based, as well as renewable energy sources, such as photovoltaic and wind based, among others, make the development of different powering solutions for remote sensing units possible. The main purpose of this paper is to present a flexible testing platform to characterize piezoelectric devices and to evaluate their performance in terms of harvesting energy. The power harvesting solutions are focused on converting the energy from mechanical vibrations, provided by different types of equipment and mechanical structures, to electrical energy. This study is carried out taking into account the power supply capabilities of piezoelectric devices as a function of the amplitude, frequency and spectral contents of the vibration stimulus. Several experimental results using, as an example, a specific piezoelectric module, are included in the paper.

Textiles are turning into a suitable next-generation sensing platform because of their good breathability, softness, and structural elasticity. Besides, research on self-powered piezoelectric sensors is a hot topic in wearable applications; they can perform long-term sensing and monitoring. Therefore, this paper mainly reviews the development progress of PVDF-based textiles on flexible piezoelectric sensors. In this paper, we first introduce the principle of the piezoelectric effect and the classification of piezoelectric materials; then we summarize the structure and characteristics of nanofiber mat-based, yarn-based, and fabric-based flexible piezoelectric sensors and the approaches that are employed to fabricate PVDF-based textile piezoelectric sensors such as melt spinning, electrospinning, and stretch forming processes, and so on. At last, we review their applicability in the application of electronic skin, human–computer interaction, healthcare, and human movement monitoring and demonstrate the facing difficulties and the future research directions of PVDF-based textile flexible sensors. [ABSTRACT FROM AUTHOR]

Sensors are of great importance in different aspects of research and industry. Future sensors will require high‐efficient and low‐cost manufacturing, as well as high‐performance functionality in areas, such as mechanical sensing, biomedical, and optical applications. Recent advances in 3D printing open a new paradigm for sensors fabrication as a precision, customizable, and seamless process. In this article, the state‐of‐the‐art 3D printing methods in sensors manufacturing is reviewed and the performance of the 3D printed sensing materials and devices is summarized. Special attention is paid to emerging multimaterial printing and 4D printing technologies, which will benefit the fabrication of a new generation of structures with multifunctionalities. The content on 3D printed sensors covers piezoelectric sensors, medical, and optical sensing devices. The performance of 3D printed sensors in comparison with the sensors made by traditional manufacturing is also covered. Finally, section 4 provides the viewpoints on the future development of 3D printed sensors. [ABSTRACT FROM AUTHOR]

Conical shell structures are frequently submitted to severe static and dynamic mechanical loads that can result in situations that affect the service of the systems that are part of, or even cause catastrophic failures. For this reason, a common solution is to design an active deformation control system, usually using piezoelectric patches strategically distributed along the surface of the shell structure. Moreover, these elements may be part of an energy recovery system. This paper details the methodology to topologically optimize the placement of piezoelectric elements through a characteristic function, analysing static and free vibration loading cases by means of the finite element method. Then, the optimal arrangement of the electrode with different polarization profiles is distributed throughout the entire structure. The nature of the loading cases studied corresponds to a general situation where static loads and dynamics vibration are considered. The objective function of the problem only depends linearly on the displacement fields, and therefore, the optimal electrode profile can be obtained for any combination of loads. As a consequence, this technique allows for maximising the electric charge obtained, which results in a greater capacity for monitoring, actuation and/or energy harvesting. [ABSTRACT FROM AUTHOR]

In all commercial and private sectors the electric power provides electricity. To built today's society the electrical power plays the prominent role, From the street lights to display light. The electricity is less in weight, easier to distribute and easy to transport. When a force by the foot is applied on piezo electric crystals which is placed on hard rubber, the force generated is changed into the form of electrical energy. This changed form of electrical energy is non another than the voltage which is stored in lead acid battery, it is connected to inverter. The inverter will convert the 12V DC to 230V AC used to activate the battery, hence the connected bulb glows. One part of embedded is very important at this situation. It is generally defined as computer system which basically has the timing constraints. [ABSTRACT FROM AUTHOR]