Piezoelectric Elements Research Articles

Piezoelectric small scale generator: towards near-Joule output energy generation

Research on piezoelectric microgenerators harvesting energy from vibrations led to an abundant literature, with various strategies to optimize the frequency range and output power. In contrast, for very low frequency range (<10 Hz) and/or for non-harmonic mechanical source, the large majority of the strategies are not adapted. This work deals with a small scale piezoelectric generator where the input mechanical source consists of a single force application in the range of hundreds of Newtons (i.e. typical human weight). Contrary to harmonic mechanical sources, such an application context necessitates harvesting as much as energy as possible in a single cycle. This was achieved by assembling several piezoelectric stacks within a mechanical amplification system, and to use the electric field and stress levels close to the limits of the piezoelectric elements. Ericsson cycle (i.e. thermodynamic cycle comprising two iso-electric field and two iso-stress steps) was applied to the piezoelectric material and later two device prototypes were developed in order to quantify the harvesting capabilities. Finally, in a realistic application point of view, a passive electrical interface based on Bennet’s doubler was implemented and compared to the Ericsson cycles in terms of output energy. This electrical energy management strategy successfully allowed working at ultra-high electric field (>2 kV mm−1) enabling a converted energy density close to the ultimate value. An maximal energy density of 320 mJ cm−3 was reached using Ericsson cycles, and 130 mJ cm−3 using Bennet’s doubler (∼40% of the ultimate energy density). The device comprising ∼2.4 cm3 of piezoelectric material, the net output energy converted and stored per cycle reached 320 mJ. Still, the work presented here can be adapted to other range of forces and displacements for maximizing energy harvesting.

Energy harvester based on low cost piezoelectric membrane for road traffic application

Piezoelectric harvesters are environmentally sustainable alternative electrical production technologies aimed at supplying small autonomous devices. The particular application in roads has significant potential. However, there are discrepancies about the effectiveness of these harvesters, and their costs limit their market expansion abilities. In this context, a novel harvester approach is explored that includes low-cost membrane piezoelectric patches in modified cymbal devices. The main novelty of this approach is the inclusion of an inner contact column that punctually transmits the load of the caps of the cymbal to the centre of the membrane piezoelectric patch, maximising its deformation and energy production capabilities. Experimental tests on piezoelectric elements, harvesters and embedder harvesting units have been performed with numerical simulations to optimise the design of the harvester. The results indicate that the more punctual the inner contact column is, the more electrical energy is produced, reaching values ten times greater than those of the present cymbal configuration. Embedding the harvester into a flexible pavement and positioning it under a wheel track are beneficial aspects of the execution. Finally, the dependency on the wheel speed is confirmed with wheel-track tests on a representative pad of the system.

RETRACTED: Energy harvesting analysis of hip implantin achieving sustainable development goals

In line with the United Nations' Sustainable Development Goal 3, promoting good health and well-being, this study explores a novel approach to energy-harvesting autonomous implants for intelligent orthopaedic solutions. Addressing the challenge of providing a reliable and easily accessible power source for active mechanical components and investigating piezoelectric hip prostheses' design and performance. The modified hip implant incorporates three vibration-based harvesters running in parallel, capturing energy during an average human stride through angular movements such as flexion, extension, and abduction. Finite element analysis is utilised to evaluate structural stress failure strength and refine the implant design, ensuring enhanced load transfer to the piezoelectric element and increased energy generation. The experimental results demonstrate the potential to harvest up to 55 J/s of helpful power and 1.76 V, contributing to the development of sustainable and reliable intelligent hip implants that can operate continuously without being disabled and work without risk. This innovative approach supports advancements in healthcare technology and improved patient outcomes, emphasising the importance of sustainable and accessible solutions in the orthopaedic field. Future research will delve into energy conversion and fatigue in complete hip implant designs, further promoting health, well-being, and sustainability in healthcare solutions.

Dynamic stiffness formulation for a piezoelectric array element

The formulation for developing the dynamic stiffness matrix for a piezoelectric array element with arbitrary boundary conditions is presented in this paper. Gorman's superposition method is innovatively utilized to obtain the solutions of the governing equations of motion for piezoelectric materials. Boundary conditions are satisfied in a strong form and Projection method is adopted for solving the spatial dependence. The results obtained for a piezoelectric array element operating as a transmitter and receiver are validated by the finite element method using COMSOL Multiphysics.

Aerosolization Performance of Immunoglobulin G by Jet and Mesh Nebulizers

Recently, many preclinical and clinical studies have been conducted on the delivery of therapeutic antibodies to the lungs using nebulizers, but standard treatment guidelines have not yet been established. Our objective was to compare nebulization performance according to the low temperature and concentration of immunoglobulin G (IgG) solutions in different types of nebulizers, and to evaluate the stability of IgG aerosols and the amount delivered to the lungs. The output rate of the mesh nebulizers decreased according to the low temperature and high concentration of IgG solution, whereas the jet nebulizer was unaffected by the temperature and concentration of IgG. An impedance change of the piezoelectric vibrating element in the mesh nebulizers was observed because of the lower temperature and higher viscosity of IgG solution. This affected the resonance frequency of the piezoelectric element and lowered the output rate of the mesh nebulizers. Aggregation assays using a fluorescent probe revealed aggregates in IgG aerosols from all nebulizers. The delivered dose of IgG to the lungs in mice was highest at 95 ng/mL in the jet nebulizer with the smallest droplet size. Evaluation of the performance of IgG solution delivered to the lungs by three types of nebulizers could provide valuable parameter information for determination on dose of therapeutic antibody by nebulizers.Graphical abstract

Piezoelectric Metamaterial Blood Pressure Sensor

Continuous blood pressure monitoring allows for detecting the early onset of cardiovascular disease and assessing personal health status. Conventional piezoelectric blood pressure monitoring techniques have the ability to sense biosignals due to their good dynamic responses but have significant drawbacks in terms of power consumption, which limits the operation of blood pressure sensors. Although piezoelectric materials can be used to enhance the self-powered blood pressure sensor responses, the structure of the piezoelectric element can be modified to achieve a higher output voltage. Here, a structural study on piezoelectric metamaterials in blood pressure sensors is demonstrated, and output voltages are computed and compared to other architectures. Next, a Bayesian optimization framework is defined to get the optimal design according to the metamaterial design space. Machine learning algorithms were used for applying regression models to a simulated dataset, and a 2D map was visualized for key parameters. Finally, a time-dependent blood pressure was applied to the inner surface of an artery vessel inside a 3D tissue skin model to compare the output voltage for different metamaterials. Results revealed that all types of metamaterials can generate a higher electric potential in comparison to normal square-shaped piezoelectric elements. Bayesian optimization showed that honeycomb metamaterials had the optimal performance in generating output voltage, which was validated according to regression model analysis resulting from machine learning algorithms. The simulation of time-dependent blood pressure in a 3D skin tissue model revealed that the design suggested by the Bayesian optimization process can generate an electric potential more than two times greater than that of a conventional square-shaped piezoelectric element.

Nanoarchitectonics of ethylene propylene diene monomer (EPDM) composites reinforced with Cu–Al–Zn-alloy for ultrasonic array transducers’ fabrication

In response to the continuous demand for industry progress and the need for low-cost alternative materials that have superior properties than the present ones, a new coupling agent was used to treat composites, which were used as new backing materials in ultrasonic array transducers. In array transducers, back-echo reverberation to the piezoelectric elements occurs, so backing materials are critical in reducing these echoes. The Cu–Al–Zn-alloy was treated with a coupling agent before being incorporated into ethylene propylene diene monomer (EPDM) composites. Cu–Al–Zn-alloy/EPDM composites were assessed using rheometric, mechanical, and morphological properties. The division of cu-alloy at the EPDM matrix was visualized using a scanning electron microscope (SEM). TGA and DSC techniques were used to study the thermal characterization of the EPDM composites. As a result, the treated Cu-alloy improved the thermal, mechanical, and morphological characteristics of EPDM composites. Ultrasonic measurements ensured the composites' effectiveness as backing materials in ultrasonic array transducers. Furthermore, the composites’ properties were similar to those of the most commonly used epoxy/tungsten backing material. Finally, linear ultrasonic-phased array transducers were fabricated using Cu–Al–Zn-alloy/EPDM composites. They had a low signal-to-noise ratio, and this ensured the effectiveness of Cu–Al–Zn-alloy/EPDM composites as backing materials.

A SİMPLE, COMPACT AND RİGİD QUESTİONNAİRE-TYPE PİEZOELECTRİC STEPPER MOTOR WİTH A LARGE STEP SİZE

Nowadays, piezoelectric motors are used as amplifiers and receivers. The principle of operation of piezoelectric stepper motors, which is the subject of the article, explains a small centrifugal inertial moving system. Piezoelectric measurement technology is a good tool that can be used under conditions with some extreme dynamics, temperature and geometry applications that are difficult to measure with the devices used in our daily measurements. The piezoelectric effect was discovered by the Curie brothers in the 1880s. It is based on the principle of creating a surface potential difference when crystals that do not contain a center of symmetry are stressed in appropriate directions. When making an engine with piezoelectric elements, nano-sized engines are designed using certain nano technologies. All these are executed with high precision. In this scientific paper, the fields of application, a simple, compact and rigid questionnaire-type piezoelectric stepper motor with a large step size are discussed. Keywords: piezoelectric motor, bimorph, inertia, working principle

Graphene Solution‐Gated Field‐Effect Transistor for Ultrasound‐Based Wireless and Battery‐Free Biosensing

AbstractThe development of wireless and battery‐free sensors for biomedical applications is a fast growing research and industrial field. It promises to greatly improve the patient's comfort during the diagnosis phase, but also in the treatment of chronic diseases. While the standard technologies are based so far on electromagnetic waves, ultrasonic powering and communication is offering perspectives to further reduce the size of the sensor in order to develop minimally invasive electronic implants. Wireless and battery‐free ultrasound‐based devices for healthcare monitoring comprise a piezoelectric element for the powering and communication, and a variable shunt load that varies according to a physiological parameter of interest. The changes in the load modify the acoustic reflectivity of the piezoelectric element, which can be detected using a pulse‐echo protocol. In the present study, the use of graphene solution‐gated field‐effect transistor is introduced as a new type of shunt load. Using an mm‐sized device, it is shown that the amplitude of an ultrasonic wave that reflects on the piezoelectric component is modulated by the voltage applied on the gate of the transistor both in physiological medium and biological tissue. This study sets the basis toward a new type of ultrasound‐based wireless and battery‐free biosensors.

Design of a Pediatric Rectal Ultrasound Probe Intended for Ultra-High Frequency Ultrasound Diagnostics.

It has been shown that ultra-high frequency (UHF) ultrasound applied to the external bowel wall can delineate the histo-anatomic layers in detail and distinguish normal bowel from aganglionosis. This would potentially reduce or lessen the need for biopsies that are currently mandatory for the diagnosis of Hirschsprung's disease. However, to our knowledge, no suitable rectal probes for such a use are on the market. The aim was to define the specifications of an UHF transrectal ultrasound probe (50 MHz center frequency) suitable for use in infants. Probe requirements according to patient anatomy, clinicians' requests, and biomedical engineering UHF prerequisites were collected within an expert group. Suitable probes on the market and in clinical use were reviewed. The requirements were transferred into the sketching of potential UHF ultrasound transrectal probes followed by their 3D prototype printing. Two prototypes were created and tested by five pediatric surgeons. The larger and straight 8 mm head and shaft probe was preferred as it facilitated stability, ease of anal insertion, and possible UHF technique including 128 piezoelectric elements in a linear array. We hereby present the procedure and considerations behind the development of a proposed new UHF transrectal pediatric probe. Such a device can open new possibilities for the diagnostics of pediatric anorectal conditions.

3D Printing and processing of miniaturized transducers with near-pristine piezoelectric ceramics for localized cavitation

The performance of ultrasonic transducers is largely determined by the piezoelectric properties and geometries of their active elements. Due to the brittle nature of piezoceramics, existing processing tools for piezoelectric elements only achieve simple geometries, including flat disks, cylinders, cubes and rings. While advances in additive manufacturing give rise to free-form fabrication of piezoceramics, the resultant transducers suffer from high porosity, weak piezoelectric responses, and limited geometrical flexibility. We introduce optimized piezoceramic printing and processing strategies to produce highly responsive piezoelectric microtransducers that operate at ultrasonic frequencies. The 3D printed dense piezoelectric elements achieve high piezoelectric coefficients and complex architectures. The resulting piezoelectric charge constant, d33, and coupling factor, kt, of the 3D printed piezoceramic reach 583 pC/N and 0.57, approaching the properties of pristine ceramics. The integrated printing of transducer packaging materials and 3D printed piezoceramics with microarchitectures create opportunities for miniaturized piezoelectric ultrasound transducers capable of acoustic focusing and localized cavitation within millimeter-sized channels, leading to miniaturized ultrasonic devices that enable a wide range of biomedical applications.

High-performance ultrasonic transducer based on PZT piezoelectric ceramic for high-temperature NDE

Piezoelectric ultrasonic transducers (PUT) are applied in a wide range of fields such as non-destructive evaluation (NDE), medical imaging and petroleum exploration, etc. Nevertheless, most PUTs cannot achieve high performance and high operating temperatures simultaneously because of the inverse correlation between piezoelectric property and operating temperature. In this paper, a high-performance ultrasonic transducer based on PZT-5A type piezoelectric ceramic (S35) for high-temperature NDE over 300 °C was proposed. Firstly, it is found that the d33, kp, and kt of the S35 ceramic plate show great temperature stability from 50 °C to 300 °C, which is attributed to the stabilisation of the phase structure and no occurrence of obvious depolarization behavior before the Curie temperature. And then, a single-element PUT based on S35 was fabricated, and pulse-echo tests from 50 °C to 300 °C in confined heating environments were executed. The peak-to-peak value (Vpp) varies from 2.58 V to 0.753 V, which results from the increase of the permittivity of the piezoelectric element and the degradation of the acoustic contact, and the −6dB BW demonstrates excellent temperature stability with a variation less than 10%. These results indicate the great potential of this high-performance ultrasonic transducer for high-temperature NDE.

Basic principles of piezo transducer efficiency evaluation method

Piezoelectric elements are one of the sources of alternative energy, the production of which does not require the use of fossil fuels harmful to the environment and the planet's climate. In this regard, the expansion of the scope of piezoelectric elements happens more and more intensively every year. The designs of piezoelectric elements that are capable of generating electricity as a result of external mechanical influences are in high demand. This demand is due to the ability to operate the most important navigation devices, smartphones, and low-voltage chargers from the received electricity in the absence of external sources of the latter or its high cost when generated by other methods. Due to the fact that piezoelectric elements have a number of specific properties due to their crystal structure, shape, size, and electrical characteristics, it is necessary to develop the selection criteria of these devices, guided by the most rational approach based on economic feasibility, market availability, and optimal manufacturability. Currently, a wide range of models of piezoelectric elements is presented that can meet the need of any customer on the Russian market despite numerous economic sanctions. Selection of the most efficient model is a major challenge for companies that use piezoelectric elements as separate components in the composition of series-produced electronic devices. There is no methodology for selecting such products; however, they can be in great demand due to multifold offers from suppliers. The method that is suggested allows the simulation of a piezoelectric element under settings that are similar to actual operating conditions, the analysis of their impact on the displacement of the piezoelectric element’s end, which is its primary characteristic under the conditions of the considered scheme, as well as the evaluation of properties and the development of recommendations for use based on the variation of its main dimensions (length, thickness), as well as the applied voltage included in the developed model, and analysis of their influence to the displacement of the end of the piezoelectric element, which is the main characteristic of the piezoelectric element under the conditions of the considered scheme. Based on the results of modeling the piezoelectric element, the most acceptable models are selected.

A new multi-piezoelectric input synchronized switch harvesting on inductor circuit

This paper has proposed a multi-piezoelectric input synchronized switch harvesting on inductor (MI-SSHI) circuit. The MI-SSHI circuit is mainly composed of an extreme detector unit and synchronized switch harvesting on inductor (SSHI) units. The extreme detector unit generates real-time control signals. Since the principle of SSHI circuit, each voltage on piezoelectric element can be switched at different instant in a period. In this paper, two piezoelectric element inputs are selected as an example. The experimental result validates that the output power of the MI-SSHI circuit is improved by 11.67%, in comparison to the traditional S-SSHI circuit.

Fabrication of metal–polymer matching layers to improve some ultrasonic transducers for NDT and calibration

This paper investigates the impact of different matching layers on the ultrasonic transducers’ performance. Matching layers are mostly used to solve the acoustic impedance matching problem between the piezoelectric element and the test specimen. To design good matching layers, we merged the metal–polymer and mass–spring systems. Their thickness was also optimized using the quarter-wavelength approach. Silver, alumina, and copper served as mass components, while parylene served as the polymer spring component. This was the first time to use such matching materials with lead zirconate titanate (PZT) transducers. The transducers’ sensitivity increased, the beam diameter broadened, the signal-to-noise ratio reduced, and the echo-height increased. According to the findings, the developed matching layers were extremely efficient in upgrading PZT transducers, making them ideal for a variety of non-destructive ultrasonic applications such as identifying defects in various materials. In addition, the new developed transducers may be useful in calibration.

Design, performance evaluation and calibration of an indirectly-excited piezoelectric wind energy harvester via a double-bluffbody exciter

Using piezoelectric wind energy harvester to harvest energy from fluids has been an effective way to power wireless sensing systems in the last decade. In order to solve the problems of low reliability, poor environmental adaptability and narrow operating bandwidth of existing piezoelectric wind energy harvesters, a piezoelectric wind energy harvester with a double-bluffbody exciter (DE-PWEH) is proposed in this research. By summarizing the disadvantages of traditional piezoelectric wind energy harvester with upwind structure, a downwind structure was adopted to improve the ability of PWEH to adapt to high wind speed environment. In order to further improve the reliability of the DE-PWEH, a wind isolation structure and an indirect excitation structure was adopted, which means the piezoelectric element was installed inside a cylindrical shell. Therefore, this 2-DOF indirectly excited DE-PWEH could possess both high reliability and broad working bandwidth. To verify the principle feasibility and design regarding the proposed DE-PWEH, a prototype of the DE-PWEH was fabricated and tested in terms of output and operating bandwidth. The results showed that the relative size and position of the adjustable plate and cylindrical shell brought significant effects on the output and operating bandwidth. When the distance-diameter ratio was 0.6, the width-diameter ratio was 1 and the height ratio was 1, the maximum output voltage was 90.35 V and the critical wind speed was 0.96 m/s. The maximum increase of the critical wind speed was 550%, and the minimum was −85.67%. With a wind speed of 15 m/s and the optimal load resistance of 2000 kΩ, a maximum power of 2.57 mW was attained. In order to quantitatively study the performance of DE-PWEH, a data fitting method based on polynomial was proposed for the first time to calibrate PWEH performance. The sixth order polynomial fitting equation can be used to characterize the output characteristics of DE-PWEH. And in practice, 80 LEDs in series were successfully driven by the DE-PWEH. The DE-PWEH could charge the 470 μF, 1000 μF, 2200 μF and 3000 μF commercial capacitors to 2 V in 60 s, 128 s, 340 s, and 400 s, respectively.

Design of a piezoelectrically actuated hydrocephalus shunt valve

Hydrocephalus is currently managed by using traditional mechanical passive shunts. Due to their nature, these shunts have fundamental shortcomings including an increase in patient shunt dependency, absence of fault detection, and over drainage due to lack of shunt proactivity. There is a scientific consensus that the way forward to address these issues is through what is termed a smart shunt. The core component of this system is the mechatronic controllable valve. A design of a valve which utilises both the passive nature of the classical valves and the controllability feature of the fully automated valves is presented in this paper. The valve consists of a fluid compartment, a linear spring, and an ultrasonic piezoelectric element. The valve is designed to operate on a 5 V supply, to drain up to 300 mL/h, and it has an operational range between 10 and 20 mmHg. The design produced is considered feasible as it takes into consideration the multiple operation conditions associated with such an implanted system.Graphical

Ultrasonic Transducers for In-Service Inspection and Continuous Monitoring in High-Temperature Environments.

The inspection of structures operating at high temperatures is a major challenge in a variety of industries, including the energy and petrochemical industries. Operators are typically performing nondestructive evaluations using ultrasound to monitor component thicknesses during scheduled shutdowns, thereby ensuring safe operation of their plants. However, despite being costly, this calendar-based approach may lead to undetected corrosion, which can potentially result in catastrophic failures. There is therefore a need for ultrasonic transducers designed to withstand permanent exposure to high temperatures, so as to continuously monitor the remnant thicknesses of structures in real time. This paper discusses the design of a heat-resistant ultrasonic transducer based on a piezoelectric element. The piezoelectric material, the electrodes, the backing layer, the wires and the casing are presented in detail from the acoustic and thermal expansion point of view. Four transducers optimized for 3 MHz were manufactured and tested to destruction in different conditions: (1) 72-h temperature steps from room temperature to 750 ∘C, (2) thermal cycles from room temperature to 500 ∘C and (3) 60 days of continuous operation at >550 ∘C. The paper discusses the results, as well as the effect of temperature over time on the properties of the transducer.

Simulation and Experiment of Trapezoidal Beam‐Based Piezoelectric Energy Harvesters

Piezoelectric energy harvesters (PEHs) are thought to be one of the best ways to power wireless sensors. However, how to improve the electrical properties of PEHs is still a key matter. Herein, a trapezoidal beam (TB) is adopted to improve the electrical outputs of PEHs, where the elastic substrate and thinned piezoelectric ceramic element are combined to obtain a piezoelectric beam with 100 μm total thickness. The simulation results indicate that the TB‐based piezoelectric energy harvester (TB‐PEH) possesses a better electrical output performance than the traditional rectangular beam‐based piezoelectric energy harvester (RB‐PEH). The presented TB‐PEH can generate a 5.4 V voltage output, and an average power of 0.2 mW with the 55 kΩ optimal resistance. The 100, 220, and 470 μF capacitors are used to demonstrate charging from the TB‐PEH, and these capacitors are saturated at 5.1, 5.0, and 4.9 V during 40, 85, and 175 s charging time, respectively. The energy harvester can generate enough power to directly light up four light emitting diodes in real time, indicating its potential to be used as microenergy source for wireless sensor networks in mechanical vibration circumstance under harmonic vibration excitation. The proposed TB‐PEH is conclusively proved potential for charging low‐power electronic devices.

Detection and Quantification of Asymmetrically Located Structural Damages by Mode Converted Guided Waves Using Piezo Electric Elements

Though damage identification using guided waves generated using ultrasonics is well proven, its usage for structural health monitoring poses difficulties. Piezo electric actuation and sensing overcomes this difficulty to some extent. In this work, usage of such guided waves for damage identification is investigated. Piezo electric wafer transducers are used for generating and sensing the guided waves. Presence of multiple modes and comparatively higher speeds of the guided waves throw up difficulties in damage identification. It is shown here that this problem can be addressed by considering different sensor location with respect to the damage with suitable interpretation of the results. Usage of fundamental antisymmetric (Ao) mode is found to be more suitable in localizing the damage compared to the fundamental symmetric (So) mode. Asymmetrically located damage causes mode conversion. It is demonstrated in this work that the mode converted guided wave (So) could be advantageously used for identification, localization, and quantification of the damage. Damage identification and localization schemes are evolved based on the location of the sensors with respect to the damage. It is shown that the reduction in the magnitude of the mode converted wave can be utilized for assessing the depth of the damage. 3D finite element based numerical models incorporating a PZT sensor are developed and validated with experimental results in terms of the characteristics of the waves, mode conversion due to damage and influence of the defect size on the received signals which are necessary for quantification of the damage.