Single Piezoelectric Element Research Articles

Development of a frequency-controlled inertial type piezoelectric locomotion method with nano-scale motion resolution driven by a symmetrical waveform

This study proposes and analyzes a novel inertial type piezoelectric locomotion method that can achieve bi-directional motion with a single piezoelectric element under a symmetrical sawtooth wave. In a stepwise approach, the dynamic responses of the guide at valley/peak points and rising/falling phases are different, and can be transformed into forward or backward stepping motion of a slider via friction by adjusting the driving frequency. A dynamic model is established and a compact prototype is developed to better understand this novel locomotion method. Simulations and a series of experiments verify that the proposed locomotion method can achieve reliable bi-directional motion under various conditions. Maximum velocities of 1.764 mm/s forward and 2.248 mm/s backward were achieved at frequencies of 300 Hz and 400 Hz, respectively. In addition, the stepping resolution was observed to reach 20 nm forward and 13 nm backward at respective frequencies of 175 and 350 Hz. The frequency-controlled locomotion method is outstanding in fast and fine actuation, and greatly simplifies the design and control of existing inertial type piezoelectric actuators.

Piezoelectric energy harvesting from rail track vibration using frequency up-conversion mechanism

Piezoelectric energy harvesting has great powering potential in railway applications, but current piezoelectric literature for rail track vibration mainly focuses on a single piezoelectric element or piezoelectric cantilever, whose output power is usually at the level of µW. In this work, a piezo stack energy harvester using the frequency up-conversion method with attractive magnetic force is proposed and experimentally validated for harvesting energy from rail track vibration. It consists of two parts, an inertial mass system and a piezo stack system. The frequency up-conversion mechanism is realised by allowing the inertial mass to attach and detach the piezo stack transducer periodically with the help of the attractive magnetic force. The attractive magnetic force contributes to the collision between the two systems, especially when the excitation frequency is near the resonant frequency. A theoretical model of the proposed energy harvester considering the colliding motion and magnetic force is established. A prototype is fabricated and can generate a peak power of 96.69 mW and average power of 2.59 mW at an input acceleration of 1 g applied at 9 Hz with an optimum load impedance of 200 Ω.

Characterization of bulk piezoelectric element-based ultrasonic motors

We propose miniature ultrasonic motors using stators made of a single bulk piezoelectric element. The bulk piezoelectric stator has the potential to increase output by reducing the dissipation that occurs in the adhesion layer between the PZTs and a metallic component in the stator. In this paper, we build two kinds of bulk piezoelectric stators: a cubic bulk stator with a side length of 4.2 mm and a hole of 3 mm in diameter, and a cylindrical bulk stator with an outer diameter of 4.2 mm and the same hole diameter. We evaluate their electrical and mechanical characteristics, such as impedance and vibration velocity. The experiments clarify the advantages of the bulk piezoelectric stators, such as low dissipation. The cubic bulk stator, which shows higher performance than the cylindrical one, is compared with a similar-shaped stator using a bronze cube and thin piezoelectric plates. The performance measures of the cubic bulk ultrasonic motor are optimized by the preload between the stator and rotor.

Asymmetric indirect-driven self-sensing actuation and its application to piezoelectric systems

Self-sensing actuators use a single piezoelectric element as actuators and sensors simultaneously. This paper proposes the asymmetric indirect-driven self-sensing actuation (AIDSSA) circuit to realize the concept of self-sensing in piezoelectric-actuated systems. Unlike traditional circuits relying on differential amplifiers, the AIDSSA circuit is constructed with only op-amps and uses negative feedback to reject the common-mode interferences from the control command. The new circuit requires simpler conditions of component matching and is able to sense the mechanical responses with a uniform gain and without a phase lag. The actuator is able to achieve full-stroke actuation while sensing is performed, because AIDSSA introduces no undesirable dynamics into the control loop. For the first time, the sensing and actuation transfer functions in self-sensing actuators have become fully decoupled at all frequencies. The investigation takes the form of an industrial application of hard disk drives, and demonstrates the usefulness the circuit in complex positioning systems. Experimental results show that the position error variance, a measure of disturbance rejection capability, has been improved by about 15% in the track-following mode relative to the same servo before modifications.

A linear actuator with an SMA clamping mechanism for dual-slider positioning

In this paper, a linear actuator with a shape memory alloy (SMA) clamping mechanism for dual-slider positioning is proposed by using a single piezoelectric element (PZT). The linear actuator consists of an SMA clamping mechanism, a PZT, a permanent magnet, a steel plate, and a base with a guide way. The SMA clamping mechanism and the steel plate serve as a slider 1 and a slider 2, respectively. When the SMA clamping mechanism releases from the guide way, the slider 1 can be driven as an impact drive mechanism. On the other hand, when the SMA clamping mechanism clamps on the guide way, the slider 2 can be driven as a smooth impact drive mechanism. In the resting state, the SMA clamping mechanism clamps on the guide way to ensure the stability of the whole system. To investigate the performance of the SMA clamping mechanism and the linear actuator, a prototype was constructed with a compact size of 40 mm (L) × 15 mm (W) × 12 mm (H). Experimental results confirmed that the dual slides could be driven independently by clamping and releasing the SMA clamping mechanism. It was verified that both the sliders can achieve long motion ranges of several millimeters and high resolution of tens of nanometers.

Analysis according to the change in structure of ultrasonic sensors and the change in pressure inside the tank for measurement of fuel amounts in compressed natural gas (CNG) tank

AbstractThe present study is a fundamental research for precise measurement of fuel amounts in a compressed natural gas (CNG) tank where an analysis of receiving sensitivity was conducted as a result of changes in the contact surface shape in the number of piezoelectric element of the ultrasonic sensor as well as in the internal pressure of the tank. Experiments were conducted as a function of changes in the contact surface shape between the ultrasonic sensor and outside of the aluminum tank and in the number of piezoelectric element as well as in the internal pressure of the tank. According to the experimental results, it could be confirmed that the maximum receiving sensitivity value was increased by about 60 % when the contact surface shape of the transmission and receiving ultrasonic sensors compared with the ultrasonic sensor in the Line‐Line shape selected as the reference model was changed to the surface. As a whole, the highest receiving sensitivity values were observed when the transmission sensor of surface shape produced as multiple piezoelectric elements and the receiving sensor of surface shape produced as a single piezoelectric element were used. It could be confirmed that receiving sensitivities were improved at the same voltage value as a result of changes in the contact surface shape of the ultrasonic sensor and in the number of piezoelectric elements.

Study of an inertial piezoelectric energy harvester from a backpack

Harvesting energy from human motions for powering portable or wearable electronic devices is attracting attentions in recent years. In this paper, an inertial energy harvester based on a piezoelectric cantilever beam is investigated for harvesting energy from a backpack. Vibration levels in the backpack during walking or jogging were tested and analyzed. Theoretical analysis was explored to determine parameters of the harvester. The generated power of the cantilever beam was experimentally studied. The experimental results show that the harvester can achieve a power output of 43.64 μW with a single piezoelectric element.

Algorithm for the layout of a piezoelectric element in an elastic medium providing the maximal piezoelectric effect within a specified frequency range

ABSTRACTAn algorithm for the layout of a piezoelectric that provides the most efficient performance within a specified range of vibration frequencies is proposed in this paper. This algorithm is based on the consideration of a special parameter within the area of a piezoelectric element’s possible location. This parameter characterizes the superposition of electromechanical coupling coefficients’ for all the natural vibration frequencies included in a specified frequency range. The condition for defining the best option for location of the piezoelectric element in the case of several equivalent positions is specified. The efficiency of the proposed algorithm is shown numerically. The electromechanical coupling coefficients were calculated numerically based on solution to the problem of natural vibrations for electroelastic bodies using a finite element method. The calculations were performed to define the best location for a single piezoelectric element at the surface of a thin-walled shell having a half-cylindrical shape. The results are presented for natural vibration frequencies within the frequency range from 0 up to 1100 Hz. The numerical results were obtained by solving the problem of natural vibrations with a finite element method using the ANSYS software package.

Self-Sensing Vibration Suppression of Piezoelectric Cantilever Beam Based on Improved Mirror Circuit

The self-sensing technique allows a single piece of piezoelectric element to function simultaneously as an actuator and a sensor in a closed-loop system. This study proposes an improved vibration suppression system using the piezoelectric self-sensing technique whose usefulness is experimentally verified in a cantilever beam. A single piezoelectric element is bonded to the root of the beam and functions as an actuator and a sensor simultaneously. A mirror circuit constructed with two charge driver circuits is used to pick up the sensing signal from the driving voltage signal. Then, a closed-loop control strategy based on the proportion integration differentiation (PID) algorithm can adjust the sensing signal precisely to suppress the vibration of the cantilever beam quickly. The first mode of vibration is suppressed, and the amplitude of the vibration is actively dampened by a factor exceeding 96.4%. Moreover, the frequency sweep experiments demonstrate that with the PID feedback control circuit connected to the piezoelectric cantilever beam, the Q value of the system is greatly reduced, and the loss factor is increased from 0.053 to 0.288. The improved mirror circuit with PID control has a good suppression effect in the frequency range near the first order mode of the cantilever beam.

Vibration energy harvesting in vehicles by gear segmentation and a virtual displacement filtering algorithm

In this study, vibration straight-line displacements occurring during electric vehicle operations are changed into reversely rotating displacements and divided into small segments by a gear unit. Piezoelectric bending elements are used to form a cantilever beam–based energy feedback mechanism for converting vibration energy into electrical power within an allowable displacement range. A virtual vibration displacement filtering algorithm is proposed to effectively filter virtual displacements that cannot excite the energy harvester and generate electrical power. The average speed of the gear exciting the bender has an accuracy 30%, which is increased using this algorithm compared with 2 other algorithms and directly affects the accuracy of calculating the average power generated by the calculation of piezoelectric bending elements. Theoretical and experimental analyses are conducted for the impact of gear pitch on the regeneration power value by changing the gear pitch at a fixed driving speed. Experiments show that when a vehicle is operated at a fixed speed, the proposed method can be used to obtain the maximum average power of a single piezoelectric bending element through determination of a rational gear pitch. Specifically, when the test vehicle operated at 20 and 60 km/h, the gear pitch should have been 7 and 10 mm.

Development of a Low-Cost Medical Ultrasound Scanner Using a Monostatic Synthetic Aperture.

In this paper, we present the design of low-cost medical ultrasound scanners aimed at the detection of maternal mortality risk factors in developing countries. Modern ultrasound scanners typically employ a high element count transducer array with multichannel transmit and receive electronics. To minimize hardware costs, we employ a single piezoelectric element, mechanically swept across the target scene, and a highly cost-engineered single channel acquisition circuit. Given this constraint, we compare the achievable image quality of a monostatic fixed focus scanner (MFFS) with a monostatic synthetic aperture scanner (MSAS) using postfocusing. Quantitative analysis of image quality was carried out using simulation and phantom experiments, which were used to compare a proof-of-concept MSAS prototype with an MFFS device currently available on the market. Finally, in vivo experiments were performed to validate the MSAS prototype in obstetric imaging. Simulations show that the achievable lateral resolution of the MSAS approach is superior at all ranges compared to the fixed focus approach. Phantom experiments verify the improved resolution of the MSAS prototype but reveal a lower signal to noise ratio. In vivo experiments show promising results using the MSAS for clinical diagnostics in prenatal care. The proposed MSAS achieves superior resolution but lower SNR compared to an MFFS approach, principally due to lower acoustic energy emitted. The production costs of the proposed MSAS could be an order of magnitude lower than any other ultrasound system on the market today, bringing affordable obstetric imaging a step closer for developing countries.

Design and experiment of piezoelectric multimodal energy harvester for low frequency vibration

Abstract Most piezoelectric vibration energy harvesters are conventional single-degree-of-freedom (SDOF) systems, and typically perform well at the single resonant mode - which makes the harvesters less efficient for low ambient vibration frequencies. In this work, we have proposed and experimentally validated a piezoelectric multimodal energy harvester having several mechanical degrees of freedom (DOFs). This multi-modal vibration energy harvester has a unique design that helps to obtain multiple resonant mode operation of the harvester at the lower frequency range. The finite element method (FEM) simulation model has been used to predict the mode shapes of the proposed energy harvester at different vibration modes. The experimental results imply that the proposed energy harvester can obtain four peak values in the range of 10–20 Hz, which are concentrated around 10, 14, 16, and 20 Hz respectively. In addition, the piezoceramic material lead zirconate titanate (PZT) has been used as a piezoelectric element that has excellent piezoelectric properties. A prototype multimodal energy harvester with four piezoelectric elements is fabricated, where a single piezoelectric element generated a peak power with a maximum of 249 µW delivered to an optimum load of 55 KΩ at 16 Hz resonant mode under 0.4 g base acceleration. In order to increase the output power and bandwidth, it is always a good idea to use multiple piezoelectric elements in one harvester structure; consequently, four piezoelectric elements of the fabricated prototype are connected in parallel. The device with parallel connected piezoelectric modules generates a peak output power of 740 µW across an equivalent optimum load resistance at 3rd resonant mode (16 Hz), while the device's base is excited at 0.4 g acceleration.

A compact time reversal emitter-receiver based on a leaky random cavity

Time reversal acoustics (TRA) has gained widespread applications for communication and measurements. In general, a scattering medium in combination with multiple transducers is needed to achieve a sufficiently large acoustical aperture. In this paper, we report an implementation for a cost-effective and compact time reversal emitter-receiver driven by a single piezoelectric element. It is based on a leaky cavity with random 3-dimensional printed surfaces. The random surfaces greatly increase the spatio-temporal focusing quality as compared to flat surfaces and allow the focus of an acoustic beam to be steered over an angle of 41°. We also demonstrate its potential use as a scanner by embedding a receiver to detect an object from its backscatter without moving the TRA emitter.

Monolithically Integrated Microelectromechanical Systems for On-Chip Strain Engineering of Quantum Dots.

Elastic strain fields based on single crystal piezoelectric elements represent an effective way for engineering the quantum dot (QD) emission with unrivaled precision and technological relevance. However, pioneering researches in this direction were mainly based on bulk piezoelectric substrates, which prevent the development of chip-scale devices. Here, we present a monolithically integrated Microelectromechanical systems (MEMS) device with great potential for on-chip quantum photonic applications. High-quality epitaxial PMN-PT thin films have been grown on SrTiO3 buffered Si and show excellent piezoelectric responses. Dense arrays of MEMS with small footprints are then fabricated based on these films, forming an on-chip strain tuning platform. After transferring the QD-containing nanomembranes onto these MEMS, the nonclassical emissions (e.g., single photons) from single QDs can be engineered by the strain fields. We envision that the strain tunable QD sources on the individually addressable and monolithically integrated MEMS pave the way toward complex quantum photonic applications on chip.

Electron–phonon metamaterial featuring nonlinear tri-interleaved piezoelectric topologies and its application in low-frequency vibration control

This article proposes a nonlinear tri-interleaved piezoelectric topology based on the synchronized switch damping on inductor (SSDI) technique, which can be applied to phononic metamaterials for elastic wave control and effective low-frequency vibration reduction. A comparison of the attenuation performance is made between piezoelectric phononic metamaterial with distributed SSDI topology (each SSDI shunt being independently connected to a single piezoelectric element) and piezoelectric phononic metamaterial with the proposed electronic topology. Theoretical results show excellent band gap hybridization (near-coupling between Bragg scattering mechanism and wideband resonance mechanism induced by synchronized switch damping networks in piezoelectric phononic metamaterials) with the proposed electronic topology over the investigated frequency domain. Furthermore, piezoelectric phononic metamaterials with proposed electronic topology generated a better low-frequency broadband gap, which is experimentally validated by measuring the harmonic response of a piezoelectric phononic metamaterial beam under clamped–clamped boundary conditions.

Design and experimental validation of a linear piezoelectric micromotor for dual-slider positioning

In this paper, a linear piezoelectric micromotor for dual-slider positioning by a single piezoelectric element (PZT) is proposed. A slider 1 and a permanent magnet are connected by the PZT, and a slider 2 is placed on the permanent magnet by the magnetic force. The slider 1 is a small steel cuboid and can be clamped and released by an electromagnet base. When it is released, it can be driven by impact friction force generated by the PZT. When it is clamped, it keeps stationary, and the slider 2 can be positioned based on the smooth impact friction drive of the micromotor. Both the sliders can be positioned independently with a long motion range as well as a high positioning resolution. Due to a single PZT used in the micromotor and miniaturized design of the mechanism, the proposed micromotor has been constructed with a compact size as well as a relatively high loading capacity.

A linear actuator for precision positioning of dual objects

In this paper, a linear actuator for precision positioning of dual objects is proposed based on a double friction drive principle using a single piezoelectric element (PZT). The linear actuator consists of an electromagnet and a permanent magnet, which are connected by the PZT. The electromagnet serves as an object 1, and another object (object 2) is attached on the permanent magnet by the magnetic force. For positioning the dual objects independently, two different friction drive modes can be alternated by an on–off control of the electromagnet. When the electromagnet releases from the guide way, it can be driven by impact friction force generated by the PZT. Otherwise, when the electromagnet clamps on the guide way and remains stationary, the object 2 can be driven based on the principle of smooth impact friction drive. A prototype was designed and constructed and experiments were carried out to test the basic performance of the actuator. It has been verified that with a compact size of 31 mm (L) × 12 mm (W) × 8 mm (H), the two objects can achieve long strokes on the order of several millimeters and high resolutions of several tens of nanometers. Since the proposed actuator allows independent movement of two objects by a single PZT, the actuator has the potential to be constructed compactly.

Designing of discrete mechatronic vibrating systems with negative value parameters

In the paper, the known problem of vibration control, authors expanded for designing of mechatronic discrete systems that contains single or multiply piezoelectric elements connected to external electric networks. Main focus has been given for investigations in relation to damping performance and parameters study, in case of potential practical application. By different configurations of considered mechatronic discrete branched structures with two degrees of freedom, key negative parameters have been identified and investigated in case of vibration control effectiveness. Results have been presented in graphical form of amplitudes and dynamical flexibility functions.

Development of a self-sensing piezoelectric pump with a bimorph transducer

This article presents a self-sensing piezoelectric pump with a bimorph transducer. The proposed method is able to realize the functions of fluid transportation and output flow and pressure self-testing simultaneously through only a single piezoelectric element. The simultaneous function is achieved through separating one lead zirconium titanate disk from the piezoelectric bimorph to detect the pumping flow or pressure in direct proportion to the bimorph deflection generated by the other actuated lead zirconium titanate disk. A prototype pump is fabricated with the size of 40 mm × 40 mm × 17 mm and tested according to the actuation frequency characteristics and voltage characteristics of the flow rate, backpressure, and sensing voltages. The testing results show that the sensing voltages are changed with the flow rate and backpressure as a function of frequency while either lead zirconium titanate disk of the bimorph act as the integrated sensor. It is found that when the pump with two distinct disks successively acting as the sensor separately achieves the maximum flow rates of 3.12 mL/min at 21 Hz and 2.93 mL/min at 22 Hz with a driving voltage of 150 Vpp, both corresponding sensing voltages also reach the maximum values of 6.88 and 6.72 Vpp, respectively. Driving voltage characteristics further indicate that both sensing voltages are linearly related to the pumping flow rate and backpressure. As a result, the sensing voltages can completely reflect the information of the flow rate and backpressure. Moreover, the pump with the piezoelectric bimorph transducer can obtain the complete self-sensing function no matter which disk of the bimorph is used as the integrated sensor.

Piezoelectric energy harvesting from vibrations induced by jet-resonator system

Inspired by musical instruments that create high amplitude tones corresponding to resonator acoustic modes when subjected to airflow, a new piezoelectric energy harvester for powering the electronic system of aircrafts is developed. It converts the incoming airflow energy into electricity via a piezoelectric transducer during the flight. With the airflow simulated by an air cylinder, prototypes of the developed energy harvester are fabricated and tested. Experimental results show that the curve of sound pressure, corresponding to the first resonator acoustic mode, is a regular sinusoidal pattern. Within the study range of airflow velocity, a linear relationship can be found not only between sound pressure and airflow velocity but also between open circuit voltage and airflow velocity. A power of above 85mW is released on a passive electric load of 3kΩ by using a single piezoelectric element of 10mm diameter at relative airflow velocity of 159m/s. And the maximum total energy conversion efficiency of the piezoelectric energy harvester is about 1.2‰. It has laid a solid foundation for powering sensors or other devices, thus eliminating a need for batteries.