Piezoelectric Resonators Research Articles

Frequency shifts in a laterally finite piezoelectric resonator loaded with a viscous liquid layer of finite size

Frequency shifts in a laterally finite piezoelectric resonator loaded with a viscous liquid layer of finite size

Rheological and Tribological Study of Polyethylsiloxane with SiO2 Nanoparticles Additive

Nowadays, much attention is paid to the creation of high-performance lubricants with improved properties through the use of ultrafine nanopowders. The paper shows the results of studying the viscoelastic properties of samples of silicon dioxide nanoparticle suspensions based on polyethylsiloxane (silicone oil) by the acoustic resonance method. The method is based on a study of the additional coupling effect on the resonance characteristics of the piezoelectric resonator. The values of the shear modulus and the tangent of the mechanical loss angle were calculated. The interaction between polymer molecules and nanoparticles was characterized by infrared spectroscopy. The influence of silicon dioxide nanoparticles (as a nano-additive) on the performance characteristics of polyethylsiloxane lubricant is presented. The results of determining the friction coefficient from the sliding speed show an increase in the tear strength of the lubricating film, leading to improved tribological properties.

Matching the Optimal Operating Mode of Polydimethylsiloxane Check Valves by Tuning the Resonant Frequency of the Resonator in a Piezoelectric Pump for Improved Output Performance.

This paper proposes to improve the output performance of a piezoelectric pump by matching the resonant frequency of the resonator to the optimal operating mode of bridge-type polydimethylsiloxane (PDMS) check valves. Simulation analyses reveal that the side-curling mode of the PDMS valve is conducive to liquid flow and exhibits a faster frequency response compared with the first bending mode. The first bending resonant frequency of a beam-type piezoelectric resonator was tuned close to the side-curling mode of the PDMS valve by adjusting the weight of two mass blocks installed on both ends of the resonator, so that both the resonator and the valve could work at their best conditions. Experiments were conducted on a detachable prototype piezoelectric pump using PDMS valves with three different lengths. The results confirm that the peak flowrate at the resonant point of the pump reaches its maximum when the resonant frequencies between the resonator and the valve are matched. Maximum peak flowrates of 88 mL/min, 72 mL/min and 70 mL/min were achieved at 722 Hz, 761 Hz and 789 Hz, respectively, for diaphragm pumps using five-, four- and three-inlet-hole PDMS valves, under a driving voltage of 300 Vpp.

Quality factor measurement based on direct energy method for piezoelectric resonator

Quality factor measurement based on direct energy method for piezoelectric resonator

Precise measurements of the low optical absorption coefficients of massive lithium triborate crystal boules with untreated facets formed during the growth process.

A spatial diagnostic of optical quality of the massive lithium triborate crystal boule with untreated facets was performed by measuring optical absorption coefficients at 1070 and 1908nm wavelengths using the piezoelectric resonance laser calorimetry technique.

Experimental study of a tunable perfect flexural wave absorber with a piezoelectric shunted resonator

Metamaterials and metasurfaces have been widely developed recently for extraordinary acoustic and elastic wave control at a deep subwavelength scale. Perfect wave absorption as an extreme case to totally absorb the impinged waves has gained great attention, whereas most existing designs based on local resonance lack tunabilities, making perfect absorption be observed at a single frequency. To overcome this drawback, in this work, we design and fabricate a tunable inductance-resistance (LR) shunted mechanical resonator via a bonded piezoelectric patch for perfect flexural wave absorption at low frequency. The LR shunted absorber could be reconfigured to a broad frequency range for perfect flexural wave absorption. The tunable perfect absorption performances are validated through experiments and unit absorption is achieved in experiments. In the end, to further highlight the advantages of shunted damping we numerically demonstrate that the absorption spectrum could be enhanced to broadband absorption with a negative capacitance and an inductance-resistance circuit (NC-LR) connected in parallel. The approach proposed provides an alternative solution to achieve perfect wave absorption in the low-frequency range and enables practical application in complex engineering structures.

Experimental investigation of rotating nodal line of MEMS-based nonlinear multi-mode resonators.

Nonlinear phenomenon is presently attracting considerable attention in the field of microelectromechanical systems (MEMS). By adjusting a controllable tuning voltage, the nonlinearity of microdevices, especially on microactuators, can be precisely manipulated. To trap and separate small particles, generating a large and stable rotation force is critical in micromanipulations. Here, we report a simple and potential angular momentum cell comprising a piezoelectric MEMS-based nonlinear multi-mode resonator with integrated electrodes. A nonlinear rotating nodal line has been observed in specific frequency bands by applying a controllable low voltage of sub 5V on a 4-port resonator made of lead zirconate titanate (PZT) thin films. The magnitude of the actuated voltage is Complementary-Metal-Oxide-Semiconductor (CMOS)-compatible and easy to integrate with the circuit. Furthermore, the real-time rotation motion of the MEMS-based nonlinear multi-mode resonator is also verified by a laser doppler vibrometer (LDV) at both chirp and single input frequencies, respectively. Therefore, this angular momentum cell shows great potential in the application of micromanipulation.

Comparison between Piezoelectric Filter and Passive LC Filter in a Class L−Piezo Inverter

This paper presents a comparison between piezoelectric filtering and passive LC filtering integrated into an HF class L−Piezo inverter. This L−Piezo inverter is a variant of class φ2 where the filtering of the second harmonic is carried out by a piezoelectric resonator. Piezoelectric filters are well known in the signal domain (RF filtering), but their use in the field of power electronics, as a temporary energy storage element, is rather recent. In power electronics, piezoelectricity has mainly been used as a transformer, in particular, to greatly increase voltages (backlight applications). A class L−Piezo inverter with Lithium Niobate (LNO) piezoelectric resonator is designed for a switching frequency of 10.4 MHz, an input voltage of 30 V, and an output power of 15 W. To compare these two filtering methods, two prototypes are built, one with piezoelectric filtering and one with passive LC filtering. Measurements show a reduction of 60% of the losses in the filter, while the volume of the filter is reduced by a factor of 50.

Intriguing dielectric phenomena in (K,Na)1-xLixNbO3 ceramics

The (K,Na)NbO3-based ceramics are a very promising type of lead-free piezoelectric materials. In spite of the scientific and technological importance, systematical investigations on the dielectric spectra had been rarely performed so far. This paper reports our study results obtained in the (K0.50Na0.50)1-xLixNbO3 ceramics with either x = 0.03 or x = 0.065 (denoted as KNLN-030 and KNLN-065 ceramics, respectively) in the unpoled state and the poled state, respectively. Before poling, the KNLN-030 ceramic shows a dielectric spectrum of strong frequency dependence with a broad peak of dielectric loss around 1 MHz, while the KNLN-065 one has a dielectric spectrum of weak frequency dependence below 60 MHz at room temperature. After poling, piezoelectric resonance peaks appear and are accompanied by a large step-like reduction of dielectric permittivity ε′ in the dielectric spectra of both two ceramics. More interestingly, the KNLN-065 ceramic exhibits an abnormal phenomenon that there is a marked increases in low-frequency ε′ upon poling, whereas the KNLN-030 one shows normally a large decrease of low-frequency ε′. Further, the KNLN-065 ceramic displays the larger low-frequency ε′ in the poled state than in the unpoled state over a considerably wide temperature range. By contrast, such abnormal phenomenon is recognized only in a limited region above the orthorhombic-tetragonal phase transition in the KNLN-030 ceramic. The analysis of domain structure suggests that the observed abnormal dielectric phenomenon possibly arises from the enhancement of domain-wall mobility.

Simulating the magnetic fields generated by piezoelectric devices using FEM software: Beyond the quasistatic approximation

A method for simulating coupled electromagnetic and mechanical vibrations on arbitrarily shaped piezoelectric structures is presented. This method is based on weak forms and can be implemented in any finite-element-method software, allowing editable access to their definitions. No quasi-static approximation is imposed, meaning that magnetic fields generated by displacement currents within piezoelectric materials are captured, enabling the flow of electromagnetic energy inside and around structures containing such material to be accurately simulated. The method is particularly relevant to the design of piezoelectric antennas, resonators, and waveguides exploiting either bulk or surface-acoustic waves. The accuracy and capabilities of the method are demonstrated by simulating, in COMSOL Multiphysics, (i) a Rayleigh mode on the surface of Z-cut lithium niobate crystal and (ii) a torsional mode of a cylinder of lead zirconium titanate (PZT-5H) ceramic functioning as a micro-antenna.

A Film Bulk Acoustic Resonator-Based Sensor with AlN Piezoelectric Material for Detecting Ethanol and Acetone

Measurement of a volatile solution is essential for laboratory safety and hospital clinic safety. In this paper, we present an ethanol-sensing and acetone-sensing device using an AlN piezoelectric material-based film bulk acoustic resonator (FBAR). In order to realize volatile solution sensing, the AlN-based FBAR was designed, fabricated, and characterized. In our sensor structure, the upper electrode is a Ti/Au (30 nm/150 nm) composite electrode, the bottom electrode is Mo material with 150 nm thickness, and the piezoelectric sensing material is 0.8 μm thickness AlN. We conducted the experiment of ethanol measurement and acetone measurement by using this FBAR detector on the probe station within the vector network analyzer. The resonance frequency of the FBAR detector decreased as the concentration of ethanol increases, while under the circumstance of acetone concentration increasing, the detector’s response is the opposite. The sensing mechanisms of both ethanol measurement and acetone measurement are discussed in this paper, demonstrating that this FBAR detector could be able to distinguish acetone from ethanol due to different sensing mechanisms.

Impact of electrode conductivity on mass sensitivity of piezoelectric resonators at high temperatures

Abstract. High-temperature stable piezoelectric Ca3TaGa3Si2O14 and La3Ga5SiO14 resonators with keyhole-shaped Pt electrodes are coated with metal oxide films such as TiO2−δ and SnO2 that overlap the Pt electrodes. The resonators are exposed to reducing atmospheres in order to increase the electrical conductivity of the oxide film and then act as extended oxide electrodes. The resulting increase in the effective electrode radius causes an increase in the mass sensitivity of the resonators and, thereby, resonance frequency shifts. In other words, the effective mass of the Pt electrode becomes higher. An electrical circuit model is presented to describe the increase in the effective electrode radius of the resonator, which is used to calculate the related resonance frequency shift. Additionally, an electromechanical model is presented, which subdivides the resonator into two coupled oscillators. One is representing the resonator volume underneath the Pt electrode and the other underneath the oxide electrode at increased electrical conductivity. The model reflects how the oxide electrodes affect the resonance frequency. Furthermore, the impact of increasing oxide electrode conductivity on the resonance frequency is discussed with respect to the application of oxide electrodes and for gas sensing.

Piezoelectric Gas Sensors with Polycomposite Coatings in Biomedical Application

When developing methods for diagnosing pathologies and diseases in humans and animals using electronic noses, one of the important trends is the miniaturization of devices, while maintaining significant information for diagnostic purposes. A combination of several sorbents that have unique sorption features of volatile organic compounds (VOCs) on one transducer is a possible option for the miniaturization of sensors for gas analysis. This paper considers the principles of creating polycomposite coatings on the electrodes of piezoelectric quartz resonators, including the choice of sorbents for the formation of sensitive layers, determining the mass and geometry of the formation of sensitive layers in a polycomposite coating, as well as an algorithm for processing the output data of sensors to obtain maximum information about the qualitative and quantitative composition of the gas phase. A comparative analysis of the efficiency and kinetics of VOC vapor sorption by sensors with polycomposite coatings and a set of sensors with relevant single coatings has been carried out. Regression equations have been obtained to predict the molar-specific sensitivity of the microbalance of VOC vapors by a sensor with a polycomposite coating of three sorbents with an error of 5-15% based on the results of the microbalance of VOC vapors on single coatings. A method for creating "visual prints" of sensor signals with polycomposite coatings is shown, with results comparable to those from an array of sensors. The parameters Aij∑ are proposed for obtaining information on the qualitative composition of the gas phase when processing the output data of sensors with polycomposite coatings. A biochemical study of exhaled breath condensate (EBC) samples, a microbiological investigation of calf tracheal washes, and a clinical examination were conducted to assess the presence of bovine respiratory disease (BRD). An analysis of the gas phase over EBC samples with an array of sensors with polycomposite coatings was also carried out. The "visual prints" of the responses of sensors with polycomposite coatings and the results of the identification of VOCs in the gas phase over EBC samples were compared to the results of bacteriological studies of tracheal washes of the studied calves. A connection was found between the parameters Aij∑ of a group of sensors with polycomposite coatings and the biochemical parameters of biosamples. The adequacy of replacing an array of piezoelectric sensors with single coatings by the sensors with polycomposite coatings is shown.

An accurate dew point sensor based on MEMS piezoelectric resonator and piecewise fitting method

Dew point sensors are widely used in various fields to provide accurate data of absolute humidity. In this paper, the dew point sensors based on MEMS piezoelectric circular resonator and cantilever are designed and fabricated. The previously reported MEMS dew point sensors suffer unavoidable errors by regarding dew point as the temperature corresponding to the maximum resonant frequency during cooling. Here, a piecewise function fitting dew point identification method is proposed, which considers the influence of relative humidity on resonant frequency and can detect dew point with small error. The results show that the piezoelectric resonant dew point sensor has good accuracy and stability, and the maximum relative error of the dew point is 0.30 °C DP. The proposed dew point sensors and method for identifying dew point have great potential in practices.

An analytical and meshless modeling for vibration analysis of an infinite quartz resonator with non-circular electrodes

An analytical and meshless modeling for solving thickness shear vibration in an infinite piezoelectric quartz resonator with partial non-circular electrodes is proposed. Firstly, two-dimensional scalar differential equations derived by Tiersten and Smythe are adopted and transformed into the polar coordinate system. Secondly, displacement patterns for the electroded and unelectroded regions are assumed as a series of converging and outgoing cylindrical waves in the form of Bessel functions, where radiation conditions at infinity can be satisfied automatically. Finally, circumferential functions at interface are decomposed into Fourier series in order to deal with continuity conditions. It should be stressed that the general formulation proposed in this paper has a higher calculation accuracy and requires no division of the mesh compared to FEM/BEM, which can satisfy continuity conditions in an integrated manner over the whole interface or boundary. Resonance frequencies and mode shapes of different electrode shapes including circular, equilateral triangle, rectangular, elliptical, and pentagonal electrodes are numerically calculated and compared with FEM simulations, which efficiently validate high precision and wide applicability of this method. Utilizing this method, the influence of non-circular electrodes on the working performance of the quartz resonator is investigated systematically. The qualitative analysis and quantitative results obtained in this paper can provide the theoretical guidance for the design, measurement and manufacturing optimization of piezoelectric resonators.

Accuracy and precision of resonant piezoelectric MEMS viscosity sensors in highly viscous bituminous materials

This paper reports on the dynamic viscosity analysis of bituminous materials with piezoelectric MEMS plate-type resonators. To enable measurements even under such strong damping conditions in this high viscous environment, the 10th order roof-tile shaped vibrational mode is exploited. For actuation and sensing, a piezoelectric aluminium nitride (AlN) thin film is used in combination with a tailored electrode design. The resonator is calibrated by measuring its conductance frequency spectrum when immersed in six high viscosity (range: 150–45.000 mPa s) test liquids at temperatures from 30 °C to 100 °C. The determination of dynamic viscosity values of bituminous materials is done using the calibration function from the linear relationship between the quality factor Q and the inverse square root of the density-viscosity product ρμ−1/2 of the test liquids. Next, Q is mapped to ρμ−1/2 for bituminous materials measured at operating temperatures from 70 °C to 150 °C. Within the measurement accuracy a very good agreement of dynamic viscosity values determined by both the MEMS resonator and a rotational viscometer is demonstrated up to a maximum dynamic viscosity of about 60.000 mPa·s. Despite this limitation these results show the outstanding potential of piezoelectric MEMS sensors for the monitoring of even super high-viscous liquid properties.

Nonlinear effects and applications for piezoelectric materials

The requirements of high quality factor, low power consumption, easy design techniques and compatibility with the main standard fabrication processes of integrated circuits (IC) make the tunable piezoelectric resonators a suitable option for the new technologies of fifth generation of telecommunication (5G) and Internet of Things (IoT). In this work the nonlinear state equations for piezoelectric effect are presented. From these equations we may deduce which materials can be used in applications where a hysteresis behavior or resonance frequency tunability are required, additionally, it is shown which crystals have the nonlinear tensor’s symmetry compatible with each application field. A novel model for the tunable piezoelectric devices is shown taking into account the consequences of voltage tuning. Finally, three different ways to design and implement the nonlinear behavior of piezoelectric materials to tune devices are introduced.

Measurement System for Piezoelectric Resonance Impedance Spectroscopy Under Combined AC and High-Voltage DC Loading.

Piezoelectric resonance impedance spectroscopy is a standardized measurement technique for determining the electromechanical, elastic, and dielectric parameters of piezoceramics. However, commercial measurement setups are designed for small-signal measurements and encounter difficulties when constant driving voltages/currents are required at resonances, higher fields, or combined AC and DC loading. The latter is particularly important to evaluate the DC bias-hardening effect of piezoelectrics. Here, we propose a novel measurement system for piezoelectric resonance impedance spectroscopy under combined AC and high-voltage DC loading that complies with established standards. The system is based on two separate output amplifier stages and includes voltage/current probes, a laser vibrometer, custom protection components, and control software with optimization algorithm. In its current form, the measurement setup allows the application of AC frequencies up to 500 kHz and DC signals up to ±10 kV on samples with impedance between 10-1 and 106 Ω . The operation of the proposed setup was benchmarked against commercial impedance analyzers in the small-signal range and reference equivalent circuits. Test measurements under combined AC and DC loading were performed on a soft Pb(Zr,Ti)O3 piezoceramic. The results revealed that a DC bias voltage applied along the polarization direction ferroelectrically hardens the material, while the material softens and eventually depolarizes when the DC bias voltage is applied in the opposite direction. The results confirm the suitability of the designed measurement system and open new exciting possibilities for tuning the piezoelectric properties by DC bias fields.

Miniature Autonomous Robot Based on Legged In-Plane Piezoelectric Resonators with Onboard Power and Control.

This work reports the design, fabrication, and characterization of a centimetre-scale autonomous robot with locomotion based on in-plane piezoelectric resonators and 3D-printed inclined legs. The robot consists of a pair of cooperative piezoelectric motors, an electronic power circuit and a battery-powered microcontroller. The piezoelectric motors feature a lead zirconate titanate (PZT) plate of dimensions 20 mm × 3 mm × 0.2 mm vibrating on its first extensional resonant mode at around 70 kHz. A particular position of 3D-printed inclined legs allowed the conversion of the in-plane movement into an effective forward thrust. To enable arbitrary trajectories of the robot on a surface, two parallel piezoelectric plate motors were arranged in a differential drive scheme. The signals to excite these plates were generated by the microcontroller and adapted by a supplementary electronic circuit to increase the effective voltage supplied by the onboard battery. The fully assembled robot had a size of 27 mm × 15 mm and a weight of 7 g and reached a linear speed of approximately 15 mm/s and a rotational speed of up to 50 deg./s. Finally, the autonomous robot demonstrated the ability to follow pre-programmed paths.

Quality Factor Enhancement of Piezoelectric MEMS Resonator Using a Small Cross-Section Connection Phononic Crystal

Anchor loss is usually the most significant energy loss factor in Micro-Electro-Mechanical Systems (MEMS) resonators, which seriously hinders the application of MEMS resonators in wireless communication. This paper proposes a cross-section connection phononic crystal (SCC-PnC), which can be used for MEMS resonators of various overtone modes. First, using the finite element method to study the frequency characteristics and delay line of the SCC-PnC band, the SCC-PnC has an ultra-wide bandgap of 56.6–269.6 MHz. Next, the effects of the height h and the position h1 of the structural parameters of the small cross-connected plate on the band gap are studied, and it is found that h is more sensitive to the width of the band gap. Further, the SCC-PnC was implanted into the piezoelectric MEMS resonator, and the admittance and insertion loss curves were obtained. The results show that when the arrangement of 4 × 7 SCC-PnC plates is adopted, the anchor quality factors of the third-order overtone, fifth-order overtone, and seventh-order overtone MEMS resonators are increased by 1656 times, 2027 times, and 16 times, respectively.