Showing papers on "Piezoelectric sensor published in 2012"

Piezoelectric Materials and Devices: Applications in Engineering and Medical Sciences

Abstract: Introduction Classification of Dielectric Materials Important Dielectric Parameters Electrostrictive Effect Piezoelectric Effect Pyroelectric Effect Ferroelectric Materials Poling Applications of Ferroelectric Materials Piezoelectric Characteristics Piezoelectric Coefficients Tensor Form of Piezoelectric Equations Independent Components of Piezoelectric, Elastic, and Dielectric Matrices Generator and Motor Actions of Piezoelectric Materials Strain versus Electric Field in Piezoelectric Materials Piezoelectric Coupling Coefficient k Dynamic Behaviour of a Piezoelectric Material Piezoelectric Materials Quartz Lead Zirconate Titanate (PZT) Fabrication of PZT Polymer Piezoelectric Materials Other Piezoelectric Materials Composite Piezoelectric Materials Engineering Applications of Piezoelectric Materials Gas Lighter Pressure Sensor Accelerometer Piezoelectric Gyroscope-Angular Rate Sensors Piezoelectric Microphone Piezoelectric Ultrasonic Transducers for Sound Navigation and Ranging (SONAR) Piezoelectric Tactile Sensor Energy Harvesting Piezoelectric Electronic Buzzer and Tweeter Piezoelectric Actuators Piezoelectric Motor Piezoelectric Micro Pump Piezoelectric Ultrasonic Drill Ultrasonic Cleaner Quartz Crystal Oscillator Quartz Crystal Balance Quartz Tuning Fork in Atomic Force Microscope Piezoelectric Transformer Nondestructive Testing (NDT) of Materials Using Ultrasonics Noise and Vibration Control Structural Health Monitoring Piezoelectric Sensors and Actuators in Smart Systems and Robots Medical Applications of Piezoelectric Materials Blood Pressure Monitor Piezoelectric Heartbeat Monitor Piezoelectric Tactile Sensor-Endoscopic Grasper and Minimal Invasive Surgical Instrument Piezoelectric Accelerometer-Monitoring Patient Activity and Detecting Tremors Piezoelectric Pump-Drug Delivery and Biomedical Analyses Ultrasonic Imaging Bone Density Measurement Using Ultrasound Ablation of Tumour Cells Using High-Intensity Focused Ultrasound (HIFU) Ultrasound for Drug Delivery Ultrasonic-Induced Transdermal Drug Delivery Phaco Emulsification-Cataract Surgery Therapeutic Ultrasound-Treatment of Injury, Muscular Pain, and Bone Fracture Modelling and Virtual Prototyping of Piezoelectric Devices Using Finite Element Software Tools Finite Element Method Theory of Coupled Field Finite Element Analysis for Piezoelectric Structure Introduction to FE Analysis of Piezoelectric Devices Using a Software Tool Examples of FE Analyses of Piezoelectric Devices

Modeling and Characterization of Cantilever-Based MEMS Piezoelectric Sensors and Actuators

Abstract: Piezoelectric materials are used in a number of applications including those in microelectromechanical systems. These materials offer characteristics that provide unique advantages for both sensing and actuating. Common implementations of piezoelectric transduction involve the use of a cantilever with several layers, some of which are piezoelectric. Although most analyses of such a cantilever assume small piezoelectric coupling (SPC), the validity of this assumption has not been fully investigated. This paper presents closed-form expressions for the voltage developed across a piezoelectric layer in an N-layer cantilever used as a sensor (e.g., as a microphone) and for the displacement profile of an N-layer cantilever used as an actuator. This represents the first time these closed-form expressions have been presented without making the SPC assumption and are used to determine the validity of the this assumption. Furthermore, a new, more robust experimental technique for identifying the piezoelectric coefficient is demonstrated using an aluminum nitride (AlN) cantilever beam. The developed expressions are also used to predict the voltage across a piezoelectric layer in a beam containing AlN layers in response to a pressure excitation and are shown to be in close agreement with experimental results.

Design, fabrication and characterization of high temperature piezoelectric vibration sensor using YCOB crystals

Abstract: A shear-mode piezoelectric accelerometer using YCa4O(BO3)3 single crystals (YCOB) was designed, fabricated and successfully tested for high temperature vibration sensing applications Dynamic modeling of the accelerometer was presented first, followed by YCOB single crystal sample preparation, sensor assembly and experimental setup establishment The prototyped accelerometer was tested at temperatures ranging from room temperature to 1000 °C and at frequencies ranging from 50 Hz to 350 Hz The sensitivity of the prototype was found to be 59 ± 006 pC/g throughout the tested frequency, temperature and acceleration ranges In addition, YCOB piezoelectric accelerometers retained the same sensitivity at 1000 °C for a dwell time of 9 h, exhibiting a high stability and reliability

Charge redistribution in piezoelectric energy harvesters

Abstract: Piezoelectric energy harvesting cantilevers provide a simple, compact low cost construction method for energy harvesting from vibrational sources. Beam theory predicts a linear distribution of strain along the length of the beam, but the conversion of this strain to electrical energy is dependent on the coverage of the beam with active material. In this paper, we demonstrate how re-distribution of charge within the piezoelectric leads to losses that can be as high as 25% of the potential generated power. Reducing the area coverage of the piezoelectric is shown to significantly improve cantilever power output, with the optimum coverage being 2/3.

System and method for reducing occurrences of unintended operations in an electronic device

Abstract: A method of operating an electronic device, and an electronic device, are disclosed in which occurrences of unintended operations of the electronic device, such as can occur in response to inadvertent actuations of actuators of the electronic device, are reduced. In one example embodiment, the method 500 includes detecting 510 an actuation of a first sensor that is associated with a first touch-sensitive component of the electronic device, and acquiring 512 data from an additional sensor of the electronic device. The method also includes determining 518, based at least in part upon the data, whether the actuation is valid, and either performing 524 or refraining 522 from performing at least one operation based at least in part upon the determining. In at least one additional embodiment, the first sensor is a piezoelectric sensor and the additional sensor is an accelerometer.

Exact solution of a thick walled functionally graded piezoelectric cylinder under mechanical, thermal and electrical loads in the magnetic field

Abstract: The present paper deals with the analytical solution of a functionally graded piezoelectric (FGP) cylinder in the magnetic field under mechanical, thermal and electrical loads. All mechanical, thermal and electrical properties except Poisson ratio can be varied continuously and gradually along the thickness direction of the cylinder based on a power function. The cylinder is assumed to be axisymmetric. Steady state heat transfer equation is solved by considering the appropriate boundary conditions. Using Maxwell electro dynamic equation and assumed magnetic field along the axis of the cylinder, Lorentz's force due to magnetic field is evaluated for non homogenous state. This force can be employed as a body force in the equilibrium equation. Equilibrium and Maxwell equations are two fundamental equations for analysis of the problem. Comprehensive solution of Maxwell equation is considered in the present paper for general states of non homogeneity. Solution of governing equations may be obtained using solution of the characteristic equation of the system. Achieved results indicate that with increasing the non homogenous index, different mechanical and electrical components present different behaviors along the thickness direction. FGP can control the distribution of the mechanical and electrical components in various structures with good precision. For intelligent properties of functionally graded piezoelectric materials, these materials can be used as an actuator, sensor or a component of piezo motor in electromechanical systems. Piezoelectrics are new group of materials which can be used as a sensor or actuator in electromechanical systems. These materials can exchange the mechanical deformations into electric potential and conversely, the electric potential can be exchanged to mechanical deformation. Piezoelectric sensors or actuators may be designed as many structural elements such as beam, plate or cylindrical shell. Some applications of piezoelectric structures in sensor or actuator application, while the structure is subjected to magnetic field, is important for designer and engineer. Therefore it is necessary to analyze the functionally graded piezoelectric cylinders under magnetic field subjected to mechanical, thermal and electrical loads. Lim and He (2001) proposed an exact solution for a compositionally graded piezoelectric layer

Electrothermally Actuated and Piezoelectrically Sensed Silicon Carbide Tunable MEMS Resonator

Abstract: In this letter, we present the design, fabrication, and electrical testing of a silicon carbide microelectromechanical (MEMS) resonant device with electrothermal actuation and piezoelectric sensing. A doubly clamped flexural-mode beam resonator made of cubic silicon carbide has been fabricated with a top platinum electrothermal actuator and a top lead zirconium titanate piezoelectric sensor. Electrothermal transduction has been used to drive the device into resonance and tune its frequency. Piezoelectric transduction has been used as resonance sensing technique. Electrical measurements have shown that, by increasing the dc bias of the actuating voltage from 1 to 7 V, a tuning range of 171 kHz can be achieved with a device resonating at 1.766 MHz.

Thin-Film PVDF Sensor-Based Monitoring of Cutting Forces in Peripheral End Milling

Abstract: A sensor module that integrates a thin film polyvinylidene fluoride (PVDF) piezoelectric strain sensor and an in situ data logging platform has been designed and implemented for monitoring of the feed and transverse forces in the peripheral end milling process. The module, which is mounted on the tool shank, measures the dynamic strain(s) produced in the tool and logs the data into an on-board card for later retrieval. The close proximity between the signal source and the PVDF sensor(s) minimizes the attenuation and distortion of the signal along the transmission path and provides high-fidelity signals. It also facilitates the employment of a first principles model based on the Euler–Bernoulli beam theory and constitutive equations of the piezoelectric sensor material to relate the in situ measured PVDF sensor signals to the feed and transverse forces acting on the tool. The PVDF sensor signals are found to compare well with the force signals measured by a platform-type piezoelectric force dynamometer in peripheral end milling experiments.

A high-temperature double-mode piezoelectric ultrasonic linear motor

Abstract: A miniature piezoelectric ultrasonic linear motor (piezoelectric vibrator sizes: 4.7 × 13.5 × 2 mm3) has been studied for precise actuation at 200 °C high-temperature. This piezoelectric linear motor was made of (1-x)BiScO3-xPbTiO3 piezoelectric ceramic with a high curie temperature (428 °C) and it was operated in first longitudinal and the second bending double-mode. Our experimental results showed that the linear motor moves smoothly at the temperature as high as 200 °C with a driving force of 0.35 N and a speed up to 42 mm/s.

Piezoelectric thin-film resonator and method for producing piezoelectric thin film

Abstract: A piezoelectric thin-film resonator includes a piezoelectric thin film which includes aluminum nitride containing Sc and which has a concentration distribution such that the concentration of Sc is non-uniform in a thickness direction of the piezoelectric thin film; a first electrode; a second electrode facing the first electrode across the piezoelectric thin film; and a substrate supporting a piezoelectric vibrating section defined by the piezoelectric thin film and the first and second electrodes.

Displacement sensor, displacement detecting apparatus, and operation device

Abstract: A displacement sensor (10) is provided with a long and rectangular elastic body (20). A piezoelectric element (30) is attached to the first main surface of the elastic body (20). The piezoelectric element (30) is provided with a long and rectangular piezoelectric sheet (300), and electrodes (301, 302), which are formed on both the main surfaces of the piezoelectric sheet (300). The piezoelectric sheet (300) has a poly-L-lactic acid as a material, and is at least uniaxially stretched. The piezoelectric element (30) is attached such that the uniaxial stretch direction of the piezoelectric sheet (300) forms 45 degrees with respect to the longitudinal direction of the elastic body (20). When the elastic body (20) is bent in the longitudinal direction, the piezoelectric sheet (300) stretches in the longitudinal direction, and the piezoelectric element (30) generates a voltage of a predetermined level.

Piezoelectric properties of polyamide 11/NaNbO3nanowire composites

Abstract: Polyamide 11(PA 11)/sodium niobate nanowire (NW) 0–3 composites with different volume fractions of NWs were synthesized. The electric polarization (P) was measured as a function of the applied electric field (E). The P–E hysteresis loop was used to work out the remanent polarization Pr of these materials. The dielectric permittivity and the piezoelectric strain constant were determined. Good impedance matching between inorganic and organic phases leads to higher electroactivity than conventional lead-free 0–3 composites. The piezoelectric voltage of the PA 11/NaNbO3 NW composites is of the same order as those obtained for fluorinated piezoelectric polymers. These composites could have some applications in flexible, low-cost, environmentally friendly piezoelectric sensors and actuators.

Developing passive piezoelectric MEMS sensor applicable to two-wire DC appliances with current switching

Abstract: A passive, non-contact piezoelectric microelectromechanical system sensor, aimed to perform monitoring of electricity consumption in DC electrical appliances with current switching, was proposed and demonstrated A micro-magnet was integrated into the proposed sensor and an appropriate position for locating the micro-magnet was theoretically determined A prototype piezoelectric sensor was fabricated, and an impulse piezoelectric voltage output was detected from a two-wire electrical appliance cord without using cord separator and driving power when switching a DC electric current on or off A linear relationship between the measured peak value of the impulse output voltage and the applied DC electric current was obtained The difference between the measured value and the calculated one was further theoretically considered from the view point of impedance effect

Fingerprint detection sensor and method of manufacturing the same

Abstract: There are provided a fingerprint detection sensor and a method of manufacturing the same. The fingerprint detection sensor includes a plurality of piezoelectric sensors arranged in an array on a two-dimensional plane and having a predetermined height; a filler provided to surround the plurality of piezoelectric sensors and isolating vibrations between the plurality of piezoelectric sensors; and a control unit discharging predetermined output signals through the piezoelectric sensors to detect information of an object in contact with, or close to, the plurality of piezoelectric sensors, wherein the plurality of piezoelectric sensors include first surfaces and second surfaces disposed on both ends thereof in a height direction and areas of the first surfaces and the second surfaces are different from each other.

Frequency detection in vortex flowmeter for low Reynolds number using piezoelectric sensor and installation effects

Abstract: Piezoelectric sensors are one of the most widely used sensors for vortex flowmeter application due to their low cost. Various researchers have employed piezoelectric sensor for this application. However, the location of the sensor and the performance of vortex flowmeter under disturbed conditions are seldom reported. In the present study, experimental investigations are conducted with water as the working medium in a circular pipe of diameter 52.5 mm. The optimum position of the piezoelectric sensor behind the trapezoidal bluff body is found out be 0.85 times the width of the bluff body. A new algorithm based on empirical mode decomposition and autocorrelation decay rate is suggested to identify the vortex shedding frequency under low Reynolds numbers flow condition. The performance of the flowmeter is also evaluated under different disturbed flow conditions to quantify the sensitivity of the flowmeter. The disturbances studied are single 90° bend, gate valve, globe valve, and two 90° out of plane bends. The overall uncertainty in the Strouhal number is within ±1.71%.

Optimal placement of sensors and actuators for active vibration reduction of a flexible structure using a genetic algorithm based on modified Hinfinity

Abstract: This paper is concerned with active vibration reduction of a square isotropic plate, mounted rigidly along one edge to form a cantilever. Optimal placement of ten piezoelectric sensor/actuator pairs is investigated using a genetic algorithm to suppress the first six modes of vibration. A new objective function is developed based on modified Hinfinity to locate the sensor/actuator pairs. The plate, with piezoelectric sensor/actuator pairs bonded to its surfaces, is modelled using the finite element method and Hamilton's principle based on first order shear deformation theory including bending, membrane, and shear deformation effects. The effects of piezoelectric mass, stiffness and electromechanical coupling are taken into account. The first six natural frequencies are validated by comparison with the finite element ANSYS package using two dimensional SHELL63 and three dimensional SOLID45 elements and also experimentally. Vibration reduction for the cantilever plate with piezoelectric patches bonded in the optimal location was investigated to attenuate the first six modes of vibration using a linear optimal control scheme. The new fitness function has reduced the computational cost and given greater vibration reduction than other previously published results.

Mathematical and numerical modelling of piezoelectric sensors

Abstract: The present work aims at proposing a rigorous analysis of the mathematical and numerical modelling of ultrasonic piezoelectric sensors. This includes the well-posedness of the final model, the rigorous justification of the underlying approximation and the design and analysis of numerical methods. More precisely, we first justify mathematically the classical quasi-static approximation that reduces the electric unknowns to a scalar electric potential. We next justify the reduction of the computation of this electric potential to the piezoelectric domains only. Particular attention is devoted to the different boundary conditions used to model the emission and reception regimes of the sensor. Finally, an energy preserving finite element/finite difference numerical scheme is developed; its stability is analyzed and numerical results are presented.

Different scale confinements of PVDF-TrFE as functional material of piezoelectric sensor devices

Abstract: In this paper, we report on the effect of micro- and nano-structuration on the piezoelectric properties of polymeric samples. We prepare micro-sized pillars and nano-wires (thus 1-D structures) of a piezoelectric polymer Poly(VinyliDene Fluoride-Tri FluoroEthylene) PVDF-TrFE and we compare their structural and piezoelectrical properties with a thin film (thus 2-D) of the same material. X-ray diffraction and infrared spectroscopy measurements show that the crystallization of the polymer into the ferroelectric $\beta$ -phase is affected by the size of the confinement. The direct and converse piezoelectric characterization of the three polymeric structures shows important improvements as far as the nano-structuration is reached. As a proof of concept, we demonstrate the use of the three polymeric structures as potential flexible tactile sensors and bendable energy harvesters, showing a profound effect of the micro- and nano-structuration on the device performances.

Comparison of methods of piezoelectric coefficient measurement

Abstract: The paper compares the main methods used for measuring of the piezoelectric material constants. It outlines the principle of three measuring methods most commonly used today, i.e. the frequency method, the laser interferometry method and the quasi-static method. These methods have been practically applied to piezoelectric ceramic samples. The paper describes the production of the piezoelectric ceramic samples of defined sizes in accordance with the current regulations. An NCE51 production code soft ceramic was used in the experiments. A piezoelectric charge coefficient was measured. The final values of the piezoelectric charge coefficient obtained through all the methods were compared to the catalogue values of the piezoelectric ceramic. All three methods can be described as appropriate; compared with the frequency method, the laser interferometry and quasi-static methods are rather time-consuming and more demanding with respect to preparation of the measurement experiment. The frequency method provides results within a smaller value range.

Improvement of low-frequency characteristics of piezoelectric speakers based on acoustic diaphragms

Abstract: The vibrational characteristics of 3 types of the acoustic diaphragms are investigated to enhance the output acoustic performance of the piezoelectric ceramic speaker in a low-frequency range. In other to achieve both a higher output sound pressure level and wider frequency range of the piezoelectric speaker, we have proposed a rubber/resin bi-layer acoustic diaphragm. The theoretical square-root dependence of the fundamental resonant frequency on the thickness and Young's modulus of the acoustic diaphragm was verified by finite-element analysis simulation and laser scanning vibrometer measurement. The simulated resonant frequencies for each diaphragm correspond well to the measured results. From the simulated and measured resonant frequency results, it is found that the fundamental resonant frequency of the piezoelectric ceramic speaker can be designed by adjusting the thickness ratio of the rubber/resin bi-layer acoustic diaphragm. Compared with a commercial piezoelectric speaker, the fabricated piezoelectric ceramic speaker with the rubber/resin bi-layer diaphragm has at least 10 dB higher sound pressures in the low-frequency range of less than 1 kHz.

Method and system for distributed network of nanoparticle ink based piezoelectric sensors for structural health monitoring

Abstract: The disclosure provides in one embodiment a system for monitoring structural health (172) of a structure (30). The system has a structure to be monitored for structural health (172). The system further has a distributed network of nanoparticle ink based piezoelectric sensor assemblies (120) deposited onto the structure (30). Each assembly has a plurality of nanoparticle ink based piezoelectric sensors (110) and a plurality of conductive ink power and communication wire assemblies (140) interconnecting the plurality of sensors (110). The system further has an ink deposition apparatus (142) depositing the distributed network of nanoparticle ink based piezoelectric sensor assemblies (120) onto the structure (30). The system further has an electrical power source (178) providing electrical power to the distributed network (120). The system further has a data communications network (179) retrieving and processing structural health data (174) of the structure (30) via one or more signals from the sensors (110).

A piezoelectric film type scour monitoring system for bridge pier

Abstract: An upgraded piezoelectric film type real-time scour monitoring sensor installed along the bridge pier is presented The core idea of developing this scouring sensing system is based on the physical characteristic that output voltage can be generated as the piezoelectric film is deformed by the flowing media Therefore, a sensing device can be constructed by mounting piezoelectric thin films along the rod at a fixed distance and inserting them into a guide rail beside the bridge pier The piezoelectric film embedded in the soil of the riverbed is undisturbed and the output voltage is much smaller than the one disturbed by the water current From the output signals of all the piezoelectric sensors with known locations along the depth of the pier foundation, one can trace the variation of the soil/water interface before, during and after a flood Compared with other types of scouring sensors, this piezoelectric type scouring sensor is durable, sensitive, and cost effective and works in real-time without the

Bulk acoustic wave resonator having doped piezoelectric layer with improved piezoelectric characteristics

Abstract: A bulk acoustic wave (BAW) resonator structure includes a first electrode disposed over a substrate, a piezoelectric layer disposed over the first electrode and a second electrode disposed over the first piezoelectric layer. The piezoelectric layer is formed of a piezoelectric material doped with one of erbium or yttrium at an atomic percentage of greater than three for improving piezoelectric properties of the piezoelectric layer.

Electro-optic effect of lithium niobate in piezoelectric resonance

Abstract: The electro-optic (EO) effect of a lithium niobate (LN) single crystal was analyzed around a piezoelectric resonance frequency. The EO-coefficient of the LN resonator was measured as a function of frequency. The EO-coefficient around piezoelectric resonance frequency varied with a maximum and a minimum in the frequency dependence. To explain the frequency dependence of the EO-coefficient, three effects were considered: (1) the intrinsic EO-effect excluding the effect of piezoelectric resonance, (2) the change of optical pass length due to piezoelectric displacement, and (3) the photo-elastic effect due to piezoelectric strain. The maximum of the EO-coefficient corresponded to the maximum of piezoelectric displacement at the resonance frequency, while the minimum was caused by the phase-lag between applied sinusoidal electric field and piezoelectric displacement. A new equation including the three effects as well as the phase-lag was formulated to represent the EO-effect of piezoelectric crystals. The equation gave a good agreement in the fitting of calculation to the observation.

Application testing of Sr doping effect of PZT ceramics on the piezoelectric transformer gain and efficiency proposed for MEMS actuators driving

Abstract: Effect of Sr content in lead zirconate titanate PZT ceramic system on performance of piezoelectric transformer application were studied. Our experiments provide consistent evaluation of doping strontium amount on piezoelctric coefficients values and final voltage gain and efficiency of piezoelectric transformer. Extreme values of these parameters are preferred for MEMS device effective driving. Modification of ferroelectric materials with isovalent ions, however with the bigger radii than the original atoms, significantly affects their properties. Particularly the electromechanical coefficients of (Pb1-xSrx)(Zr0,70Ti0,30)O3, for mole %’s as x = 0.05, 0.10 and 0.15 ceramics exhibit marked increase, if the PSZT material stoichiometry is near the ferroelectric/relaxor phase boundary. To determine the piezoelectric coefficients, the resonance-antiresonance method was implemented. The results indicated that addition of Sr2+ ions in the amount of 5 mol% in the ceramic structure maximally increased the values of piezoelectric parameter to d31 = 8.2 pC/N and mechanical quality factor Qm = 2902. Finally we demonstrated that in spite of the high piezoelectric coefficients for certain material only the practical examination must be applied in order to draw decisive application conclusions due to the complexity of the double energy conversion in such a specific device as the piezoelectric transformer.

Power enhancement of piezoelectric transformers by adding heat transfer equipment

Abstract: It is known that piezoelectric transformers have several inherent advantages compared with conventional electromagnetic transformers However, the maximum power capacity of piezoelectric transformers is not as large as electromagnetic transformers in practice, especially in the case of high output current The theoretical power density of piezoelectric transformers calculated by stress boundary can reach 330 W/cm3, but no piezoelectric transformer has ever reached such a high power density in practice The power density of piezoelectric transformers is limited to 33 W/cm3 in practical applications The underlying reason is that the maximum passing current of the piezoelectric material (mechanical current) is limited by the temperature rise caused by heat generation To increase this current and the power capacity, we proposed to add a thermal pad to the piezoelectric transformer to dissipate heat The experimental results showed that the proposed techniques can increase by 3 times the output current of the piezoelectric transformer A theoretical-phenomenological model which explains the relationship between vibration velocity and generated heat is also established to verify the experimental results