Showing papers on "Interdigital transducer published in 2012"

Droplet translocation by focused surface acoustic waves

Abstract: This paper presents the experimental investigations of droplet movement driven by focused surface acoustic waves (SAWs) generated by a circular-arc interdigital transducer (CIDT). Surface acoustic waves propagating through a droplet in contact with the substrate exerted an acoustic streaming force on the droplet, as demonstrated by numerical modeling in this study. Different from the straight droplet movement driven by a straight interdigital transducer (SIDT), the droplets were focused to the center region of the CIDT. In addition, the droplets driven by the CIDT moved much faster than those driven by the SIDT with an identical input power because of the concentrated acoustic energy in the CIDT. Merging of two moving droplets using the CIDT was also demonstrated. The present results show that focused SAWs can be more efficient than uniform SAWs for droplet and fluid actuation in microfluidics.

Magnetic-acoustic surface wave magnetic field sensor and preparation method thereof

Abstract: The invention relates to a magnetic-acoustic surface wave magnetic field sensor and a preparation method thereof, and belongs to the technical field of electronic functional materials and devices. The sensor comprises a piezoelectric thin film, a magnetostrictive thin film and a substrate, wherein the magnetostrictive thin film is positioned between the piezoelectric thin film and the substrate; the thickness of the magnetostrictive thin film is 2-5 times the thickness of the piezoelectric thin film; and an interdigital transducer is arranged on the surface of the piezoelectric thin film, and the interdigital transducer and the piezoelectric thin film constitute an acoustic surface wave device. A layer of SiO2 is covered on the surface of the piezoelectric thin film and the interdigital transducer. When the sensor is in resonant state, if an external magnetic field changes, the Young's modulus of a magnetostrictive layer changes, the propagation speed of acoustic surface waves in a piezoelectric layer can be further affected and then the changes of the external magnetic field can be known by detecting the changes in resonance center frequency. The SiO2 covering layer can compensate for a frequency temperature coefficient of the piezoelectric thin film and realize the frequency temperature coefficient which is close to zero. The sensor has the characteristics of miniaturization, easiness in integration, high sensitivity, good consistency, stability and reliability.

Optimization of Autonomous Magnetic Field Sensor Consisting of Giant Magnetoimpedance Sensor and Surface Acoustic Wave Transducer

Abstract: This paper presents a novel autonomous thin film magnetic field sensor consisting of a tri-layer giant magnetoimpedance sensor and a surface acoustic wave transponder. Double and single electrode interdigital transducer (IDT) designs are employed and compared. The integrated sensor is fabricated using standard microfabrication technology. The results show the double electrode IDT has an advantage in terms of the sensitivity. In order to optimize the matching component, a simulation based on P-matrix is carried out. A maximum change of 2.4 dB of the reflection amplitude and a sensitivity of 0.34 dB/Oe are obtained experimentally.

High-frequency SAW filters based on diamond films

Abstract: We have developed a diamond SAW resonator capable of operating at frequencies over 3 GHz using a SiO2/ interdigital transducer (IDT)/AlN/diamond structure. This structure is expected to have a high Q value and a zero temperature coefficient of frequency (TCF) over 3 GHz, based on the high acoustic velocity of AlN. The SAW characteristics of various layered structures composed of SiO2/IDT/AlN/diamond substrates were studied both theoretically and experimentally. The SiO2/IDT/AlN/diamond substrate structure allows for a thicker IDT metal layer compared with other SAW device designs, such as the SiO2/IDT/ZnO/diamond structure. The thicker metal IDT in the present design leads to a lower series resistance and, in turn, a low insertion loss for SAW devices over 3 GHz. Using a second-mode (Sezawa-mode) SAW, the phase velocity and electromechanical coupling coefficient of the SiO2/IDT/AlN/diamond substrate reached the larger values of 11 150 m/s and 0.5%, respectively, and a zero TCF characteristic at 25°C was achieved. One-port SAW resonators fabricated from diamond substrates showed a high Q of 660 at 5.4 GHz. The frequency drift over a temperature range of -25°C to 80°C was about 90 ppm, even less than that for ST-quartz SAW substrates. A two-port resonator showed a low insertion loss of 8 dB at 5.4 GHz. Finally, we designed a 5-GHz band-stop SAW filter. A 30-MHz-wide stopband at a -6-dB rejection level was achieved while keeping the passband insertion loss to 0.76 dB. These characteristics of these filters show good potential for SHF-band filters.

SAW (surface acoustic wave)-based passive temperature tag and SAW-based passive temperature tag reader

Abstract: The invention discloses a SAW (surface acoustic wave)-based passive temperature tag which comprises a substrate, an interdigital transducer, a tag antenna, a temperature reflecting grating and an ID (identification)-tag reflecting grating. The ID tag reflecting grating is used for identifying the detected objects by the SAW on the reflecting substrate, and the substrate is provided with the interdigital transducer used for take charging to the electro-acoustic conversion of signals. According to the SAW-based passive temperature tag, a transmitting and receiving antenna is used for transmitting and receiving radio-frequency signals, the ID-tag reflecting grating is used for identifying the detected objects by the SAW on the reflecting substrate, and the temperature reflecting grating is used for measuring temperature by the SAW on the reflecting substrate. A reader is used for reading the ID information and the temperature data which are stored in the passive temperature tag, and the data is processed in an intermediate-frequency signal processing plate. With regard to the determination of the position of the echo baseband pulse signals, the centroid position replaces the peak position, therefore, the amount of computation is reduced, and the precision is improved.

Cell, element of ultrasonic transducer, ultrasonic transducer including the same, and method of manufacturing cell of ultrasonic transducer

Abstract: An element of an ultrasonic transducer includes a first substrate, at least one cell of the ultrasonic transducer arranged above the first substrate, and a second substrate arranged under the first substrate, in which a first power supply for applying an electric signal to the first substrate is formed.

Inkjet printed all-polymer flexural plate wave sensors

Abstract: We demonstrate an all-polymer flexural-plate-wave gravimetric sensor using piezoelectric PVDF and conductive PEDOT:PSS. An inkjet-printed interdigital transducer (IDT) is used to excite Lamb waves within the film that are measured both electronically, using a second IDT, and mapped directly using a scanning laser Doppler vibrometer. Pulsed wave excitation isolates the weak acoustic signal from the electromagnetic crosstalk, enabling the measurement of relative changes in the resonant frequency, Δf/f 0 , with the addition of mass, Δm, to the sensing area. A gravimetric mass sensitivity equivalent to Δf/(f 0 Δm) = −153 cm2/g has been measured for mass loading with a polymer layer.

Rapid drop-to-drop liquid–liquid microextraction by help of surface acoustic wave

Abstract: A novel drop-to-drop liquid–liquid microextraction method is presented, by which a liquid–liquid microextraction is greatly accelerated. A pair of interdigital transducers (IDTs) with 27.5 MHz center frequency is fabricated on a 128° yx-LiNbO3 substrate. Once a RF signal is applied to an IDT, surface acoustic wave is generated and then radiated into drops to be extracted on the acoustic path. The surface acoustic wave radiation, leading to rapid movement of droplets in original position, enhances the microextraction. An ionic liquid and an organic dye aqueous solution are used for extraction experiments and extraction kinetics is studied using an image-based concentration measurement technique. Extraction experiments show that a drop-to-drop liquid–liquid microextraction process can be finished within 100 s when the RF signal power applied to the IDT is 26.9 dBm, and the extraction time is decreased with RF signal power applied to the IDT.

1 GHz bulk acoustic wave slanted finger interdigital transducers in aluminum nitride for wideband applications

Abstract: This paper presents the first experimental demonstration of bulk acoustic wave (BAW) slanted finger interdigital transducer (SFIT) delay line in aluminum nitride (AlN) thin film operating around 1 GHz. The SFIT is used to electro-acoustically transduce the Lamb wave S 0 mode. The AlN Lamb SFITs were micromachined and experimentally demonstrated to have a band-pass response with a maximum insertion loss (IL) of 26 dB, fractional bandwidth (6 dB) of 7.9%, and a shape factor (−30 dB) of 1.8. This device displays a small form factor of 150 μm × 421 μm. The transmission response of the measured devices was confirmed to match the impulse response model. However, large pass-band ripples were observed in the device due to the acoustic reflections within the interdigitated fingers. In order to verify the reflection effect, AlN lateral field excitation (LFE) SFITs were also microfabricated. Because of the absence of the bottom floating electrode and the use of a thicker AlN membrane in this configuration, the acoustic mismatch between interdigital transducers (IDTs) is reduced and so is the magnitude of the associated ripple (from 5 dB to 3.5 dB).

Investigation on the optimized design of alternate-hole-defect for 2D phononic crystal based silicon microresonators

Abstract: This paper shows the design, fabrication, and characterization of the Bloch-mode micromechanical resonators made by creating alternate defects to form a resonant cavity on a two-dimensional silicon phononic crystal slab of square lattice. The length of the resonant cavity (L) and the central-hole radius (r′) are varied to optimize the performance of the resonators. CMOS-compatible aluminium nitride is used as the piezoelectric material of the interdigital transducer to launch and detect acoustic waves. The extent of energy confinement within the cavity, as shown by the simulated displacement profiles of the resonators, agrees with the measured Q factors. We also quantitatively analysed the band structure of the proposed resonators and found that the Q factors are generally in an inverse relationship with the standard deviation of the band, due to the slow sound effect brought by flat bands which reduces the energy loss along the lateral direction (Y direction) and enhances the Q factor.

Method of producing surface acoustic wave devices by exposing X-rays

Abstract: The invention discloses a method of producing surface acoustic wave devices by exposing X-rays A master set of an interdigital transducer is produced by photoetching electron beams on a hollow polyimide self-supporting film; electron beam resist concave solid figures of the interdigital transducer are obtained by exposing X-rays on a piezoelectric substrate; and various surface acoustic wave devices are produced with the stripping technology By adopting the method of producing the surface acoustic wave devices by exposing X-rays, the back scattering effect of the material of the nano-scale interdigital transducer electrode can be greatly reduced, the nano-scale interdigital transducer electrode can be obtained, and the working performance and the performance of the surface acoustic wavedevices are improved; and in addition, the X-rays can be exposed repeatedly for many times, thus the producing efficiency of the surface acoustic wave devices is improved, and the producing cost is lowered

High-Q Aluminum Nitride RF MEMS Lamb Wave Resonators and Narrowband Filters

Abstract: Author(s): YEN, TING-TA | Advisor(s): Pisano, Albert P.; Nguyen, Clark T.-C. | Abstract: The increasing demands for higher performance, advanced wireless and mobile communication systems have continuously driven device innovations and system improvements. In order to reduce power consumption and integration complexity, radio frequency (RF) microelectromechanical systems (MEMS) resonators and filters have been considered as direct replacements for off-chip passive components. In this dissertation, a new radio architecture for direct channel selection is explored. The primary elements in this new architecture include a multitude of closely-spaced narrowband filters (i.e., a filter bank) and an array of low-loss RF switches. This work addresses a number of issues related to this modern channel-select RF front end and explores the potential of utilizing piezoelectric aluminum nitride (AlN) resonator technology to fulfill these technical challenges. Characteristic studies of acoustic waves propagating in a piezoelectric thin film suggest the use of high-phase-velocity Lamb wave mode vibration for higher frequency applications. The lowest-order symmetric modes (S0 modes) can be efficiently excited, via the d31 (e31) piezoelectric coefficient, by utilizing interdigital transducer (IDT) electrodes, enabling co-fabrication of devices operating from tens of megahertz up to a few gigahertz on the same chip. An AlN "overhang" fine frequency selection technique is experimentally studied, allowing precise relative frequency control of an array of Lamb wave resonators (LWR) to 0.1%. Experimental results suggest the resonance frequency of Lamb wave resonators can be linearly adjusted by up to 5% with no significant effects on other resonator parameters. The first high temperature testing of AlN Lamb wave resonators above 600°C verifies its potential of being used in a harsh environment sensing telemetry. With a correct AlN/SiO2 thickness ratio, the first-order temperature coefficient of frequency (TCF) of a LWR can be reduced from -25 ppm/K to 3.9 ppm/K. In addition, increasing the input power level from -15 dBm to 10 dBm causes no bifurcation instability or frequency hysteresis on AlN Lamb wave resonators and only 0.05% frequency drift is recorded, showing an excellent power handling capability. A number of different resonator topologies are studied and demonstrated in this work as possible candidates for the filter bank. Mechanically-coupled filters utilize quarter-wavelength coupling beams to eliminate the mass-loading effect to adjoining resonators, and the bandwidths are determined by the equivalent stiffness of the coupling beam and the resonator itself. Numbers of identical resonators are mechanically-coupled as a filter with center frequency at 710 MHz and 0.4% fractional bandwidth (FBW). Furthermore, by introducing AlN overhang selection technique, an array of electrically self-coupled filters are fabricated with evenly-spaced center frequencies around 735 MHz and 500 kHz bandwidths (0.07% FBW). An array of ladder filters with center frequencies around 440 MHz and 2 MHz bandwidths (0.5% FBW) are also demonstrated, without post-process trimming. These closely and evenly spaced AlN Lamb wave filters demonstrate the potential to realize a purely mechanical, high performance, yet low-power RF front-end system. To further improve filter performance, capacitive-piezoelectric Lamb wave resonators, featuring sub-micron air gaps between piezoelectric structural layer and electrodes, are demonstrated with the aim of reducing interface energy dissipation. Quality factors of these capacitive-piezo Lamb wave resonators are measured over 5,000 at 940 MHz, posting the highest reported Q for single AlN resonators using d31 (e31) transduction. The Q * f products above 4.7×10^12 exceed those of commercialized FBAR and SAW resonators. Although the motional impedance of these devices inevitably rises to 1 kilo-ohm; when electrodes are separated from the AlN, this value is still much lower than conventional electrostatic resonators and can be easily terminated with on-chip matching networks. While designing the surface micromachining fabrication process dedicated to these capacitive-piezo devices, a thorough AlN etch rate table including commonly encountered cleaning and wet/dry etch steps is established. Although a large part of this dissertation concerns Lamb wave resonators, the last part of this dissertation focuses on a special corrugated cantilever beam design to improve conversion efficacy of a piezoelectric energy harvester. These vibration-sensitive piezoelectric AlN energy harvesters utilize corrugated cross-section cantilevers to achieve the same energy conversion effectiveness as that in a bimorph beam design, yet using a simple fabrication process similar to that of a unimorph beam. Due to the opposite signs of strains, the generated electric fields above and below the neutral plane have opposite polarities, and the generated energy can be extracted separately without the common cancellation issues encountered in a single piezoelectric beam design. This approach provides superior performance while simultaneously simplifying the fabrication process. A prototype multi-fold device resonating at 853 Hz with output power of 0.17 microwatt under a 1 G acceleration is recorded. Based on superb material properties and the 600°C thermal testing performed on RF resonators, these AlN energy harvesters offer a promising solution to scavenge vibration energies from harsh environments for advanced microsensor systems.

Simplified Model for FEM Simulation of SAW Delay Line Sensor

Abstract: Surface acoustic wave (SAW) devices can be modeled using various methods such as equivalent circuit model, coupling of modes method and finite element method (FEM). FEM simulation of SAW devices serves to optimize SAW structures and allows getting insight physics of propagation of SAW over the substrate. In most of the earlier work on FEM simulation of SAW sensors, entire device structure is considered for the simulation and the number of degrees of freedom (DOF) to solve is significantly high. Thus it is important to identify valid approximation and simplified models to reduce the computational cost. In this paper a 2D-finite FEM simulation of SAW delay line model using COMSOL Multiphysics (commercial FEM software) is discussed. We have modeled a Rayleigh wave type SAW device choosing YZ Lithium Niobate as the substrate. The major contribution of this work is the application of periodic boundaries to the transmitter interdigital transducer (IDT) to reduce the number of degrees of freedom of a SAW delay line model solution. The simulation methodology and time domain response of the model are discussed.

Surface acoustic wave gas sensor

Abstract: The utility model discloses a surface acoustic wave gas sensor, which comprises a piezoelectric substrate. Two input interdigital transducers, two output interdigital transducers and two gas absorption thin films are deposited on the upper surface of the piezoelectric substrate, wherein the two input interdigital transducers are used for converting electric signals into surface acoustic wave signals; the two output interdigital transducers are used for receiving acoustic signals which are transmitted through the bottom surface of the piezoelectric substrate by surface acoustic waves generated by the input interdigital transducers, and converting the acoustic signals into the electric signals; the two gas absorption thin films are used for absorbing gas; the first input interdigital transducer, the first gas absorption thin film and the first output interdigital transducer are arranged in turns, and form a first path of surface acoustic wave delay line; and the second input interdigital transducer, the second gas absorption thin film and the second output interdigital transducer are arranged in turns, and form a second path of surface acoustic wave delay line. The surface acoustic wave gas sensor has a compact structure, a small volume, a novel and rational design, high measurement accuracy, high sensing flexibility, high working stability and good using effects, and is convenient to use, operate and popularize.

Acoustic wave filter based on periodically poled lithium niobate

Abstract: Solutions for the development of compact RF passive transducers as an alternative to standard surface or bulk acoustic wave devices are receiving increasing interest. This article presents results on the development of an acoustic band-pass filter based on periodically poled ferroelectric domains in lithium niobate. The fabrication of periodically poled transducers (PPTs) operating in the range of 20 to 650 MHz has been achieved on 3-in (76.2-mm) 500-μm-thick wafers. This kind of transducer is able to excite elliptical as well as longitudinal modes, yielding phase velocities of about 3800 and 6500 ms-1, respectively. A new type of acoustic band-pass filter is proposed, based on the use of PPTs instead of the SAWs excited by classical interdigital transducers. The design and the fabrication of such a filter are presented, as well as experimental measurements of its electrical response and transfer function. The feasibility of such a PPT-based filter is thereby demonstrated and the limitations of this method are discussed.

ENCAPSULATED ALUMINIUM NITRIDE SAW DEVICES for LIQUID SENSING APPLICATIONS

Abstract: Very low-stress and good crystallinity Aluminum Nitride (AlN) thin films deposited on (100) Silicon substrates are optimized for surface acoustic wave (SAW) devices. We developed a simplified process to fabricate AlN SAW devices suitable for fast screening of liquid substances as needed for health and environmental monitoring. By encapsulating the interdigital transducer (IDT) with a very thin SiN layer, a sufficiently large sensing area is available between the electrodes. This allows direct and fast loading of the liquid drops on the device surface as well as cleaning, for repeated use. Moreover, the amount of layers on top of the piezoelectric AlN is minimized to avoid reduction of the signal. The fabricated devices are tested by using different buffer solutions typical in biological research (NaCl and phosphate buffered saline) and the possibility to operate these SAW devices for liquid sensors is demonstrated.

Surface acoustic wave filter with high mechanical coupling factor and low insertion loss and special piezoelectric film thereof

Abstract: The invention discloses a surface acoustic wave filter with a high mechanical coupling factor and low insertion loss and a special piezoelectric film thereof. The piezoelectric film is a ZnO piezoelectric film doped with any one of V, Cr and Fe. The surface acoustic wave filter provided by the invention comprises a substrate, the piezoelectric film deposited on the substrate as well as an input interdigital transducer and an output interdigital transducer which are arranged on the ZnO piezoelectric film, wherein the piezoelectric film is the ZnO piezoelectric film doped with any one of V, Cr and Fe. By adopting a material with high surface acoustic wave speed as the substrate, a ZnO film is deposited on the substrate, an electron-beam direct writing process is adopted for preparing a submicron interdigital transducer, and a high frequency film surface acoustic wave filter with frequency greater than 4GHz can be prepared.

A Microreactor With Surface Acoustic Wave Micro-Heating System

Abstract: A new microreactor with surface acoustic wave (SAW) heating system was presented. The microreactor is comprised of surface acoustic wave heating source, a PDMS micro-vessel and a metal micro-vessel. An interdigital transducer (IDT) and a reflector were fabricated on a 1280 yx-LiNbO3 piezoelectric substrate by microelectric technology. A RF signal with 27.5 MHz frequency was applied to the IDT to generate surface acoustic wave. When hitting a glycerin microfluid in the PDMS micro-vessel on the piezoelectric substrate, SAW radiated into the glycerin microfluid and heated it. Then, the temperature of the reactants in the metal micro-vessel was raised by heating transfer. The experiments of melting solid paraffin and color development reaction have been examined using the microreactor. The results show that the temperature of the reactants in the metal micro-vessel can be raised at least 42°C, which is enough for lots of biochemical reactions. The results also show that the microreactor can greatly improve th...

Encapsulated Aluminum Nitride SAW devices for liquid sensing applications

Abstract: Very low-stress and good crystallinity Aluminum Nitride (AlN) thin films deposited on (100) Silicon substrates are optimized for surface acoustic wave (SAW) devices. We developed a simplified process to fabricate AlN SAW devices suitable for fast screening of liquid substances as needed for health and environmental monitoring. By encapsulating the interdigital transducer (IDT) with a very thin SiN layer, a sufficiently large sensing area is available between the electrodes. This allows direct and fast loading of the liquid drops on the device surface as well as cleaning, for repeated use. Moreover, the amount of layers on top of the piezoelectric AlN is minimized to avoid reduction of the signal. The fabricated devices are tested by using different buffer solutions typical in biological research (NaCl and phosphate buffered saline) and the possibility to operate these SAW devices for liquid sensors is demonstrated.

Frequency-selecting interdigital transducer

Abstract: The invention relates to a frequency-selecting interdigital transducer. The transducer comprises a piezoelectric substrate, a one-dimensional interdigital transducer and a two-dimensional metal dot matrix, wherein the one-dimensional interdigital transducer is arranged on the piezoelectric substrate, the two-dimensional metal dot matrix is arranged on the one-dimensional interdigital transducer, and a pass band or a stop band is generated by selecting a specific value between the period of the two-dimensional metal dot matrix and the period of one electrode of the one-dimensional interdigital transducer. Matrix elements of the two-dimensional metal dot matrix are made of copper, tungsten or gold. The electrode of the one-dimensional interdigital transducer is made of aluminium, copper or gold. The piezoelectric substrate is made of lithium tantalite, lithium niobate or quartz. When a proportion between the period of the electrode of the one-dimensional interdigital transducer and the period of the two-dimensional metal dot matrix is in the range of 1.1 to 6.6, the band-pass frequency characteristic is realized. When a proportion between the period of the one-dimensional interdigital transducer and the period of the two-dimensional metal dot matrix is in the range of 0.2 to 6, the band elimination frequency characteristic is realized.

Single-scale surface acoustic wave type wavelet transform processor

Abstract: The invention provides a single-scale surface acoustic wave type wavelet transform processor which is characterized by comprising a piezoelectric substrate material, wherein an input transducer and an output transducer are manufactured on the piezoelectric substrate material; the strip area of the input transducer is designed according to the enveloping area of a single-scale Morlet dyadic wavelet function; and the output transducer is an interdigital transducer with equally-overlapped and uniform-period strips. The single-scale surface acoustic wave type wavelet transform processor provided by the invention can be used for overcoming the defects in the prior art and has a diffraction inhibition function.

Intelligent tool for monitoring multiple physical quantities of machining state in real time

Abstract: An intelligent tool for monitoring multiple physical quantities of a machining state in real time belongs to the technical field of machining tools and detection The intelligent tool has the function of wirelessly sensing and monitoring the multiple physical quantities of a tool cutting area in real time The intelligent tool comprises a tool matrix and functional coatings, the functional coatings include a cutting coating, a sensor coating and an outermost protective coating, the cutting coating is coated on the tool matrix, the protective coating is coated on the surface of the sensor coating, the sensor coating comprises a piezoelectric film layer, an interdigital transducer array and a radio frequency antenna, the interdigital transducer array is integrated in the piezoelectric film layer, the radio frequency antenna is connected with the interdigital transducer array, the multiple physical quantities of the machining state of the tool cutting area are sensed, and monitoring signals are wirelessly transmitted The intelligent tool integrates a sensing system coating and the functional coatings of the tool, and is simple in structure, convenient in installation and use, capable of wirelessly detecting the multiple physical quantities of the state of the tool cutting area, and suitable for real-time monitoring of the machining state of a rotary tool

High frequency surface acoustic wave device with AlN (aluminum nitride) film as interlayer and preparation method thereof

Abstract: The invention provides a high frequency surface acoustic wave device with an AlN (aluminum nitride) film as an interlayer. The device is characterized in that an a-axis preferred orientation AlN film is taken as a CVD (chemical vapor deposition) diamond substrate and a c-axis preferred orientation ZnO film is taken as an interlayer, the substrate and the interlayer are formed into an IDT(interdigital transducer)/ZnO/a-axis preferred orientation AlN/diamond multi-layered membrane structure and the structure is stacked with the IDT in sequence to form the high frequency surface acoustic wave device; the preparation method comprises the following steps of preparing an a-axis preferred oritention AlN film interlayer, and preparing a c-axis preferred oritentation ZnO film on the a-axis preferred orientation AlN film interlayer. The device and the preparation method provided by the invention have the following advantages that the sound velocity frequency dispersion caused by a large sound velocity gap between nanodiamond and ZnO can be solved, the application demand of the surface acoustic wave with high frequency above 4.8 GHz can be met, and moreover, the process is simple and easy to implement, and is beneficial for large-scale population and application.

SAW Delay Line for Vibration Sensors

Abstract: The paper presents an analysis of surface acoustic wave delay line. The line consists of two simple interdigital transducers placed on a ST-cut quartz plate. Mid-band operation frequency of the line is 74 MHz. The line will be applied for surface acoustic wave vibration sensor. At the immovable end of the plate there are electric signal feeds to both transducers. This is the cause of increase in signal value going directly between the transducers and the cause of line losses. By means of equivalent electric model of interdigital transducer a loss analysis of the line has been made at 50 Ω load. The analysis allows to minimize line losses by matching the transducers to 50 Ω impedance. This has been practically achieved by a design of transducer geometry and con guration matching 50 Ω impedance, by means of inductance. An analysis of repeated operation characteristics of two interdigital transducers has been made. A signal going directly through capacitance between transducers and signals re ected from the edge of piezoelectric substrate have been presented. Results of theoretical analysis have been compared with experimental examinations.

Finite difference time domain analysis of two-dimensional piezoelectric phononic crystals

Abstract: Phononic crystals (PCs) have promising band gaps, in which Surface Acoustic Wave (SAW) propagating is prohibited. Several numerical methods have already been developed and applied to analyze piezoelectric PCs, most of them have various disadvantages, as they cannot calculate the transmission characteristic of the limited structure or cannot provide the propagation process for SAW in time domain. The finite-difference time-domain (FDTD) technique solving these problems is adopted to analyze the piezoelectric characteristics of PCs. Propagation in the PCs is studies by experience with direct generation and detection of SAW using interdigital transducers (IDT's). The simulation data agrees with the measurement data. Therefore the FDTD method is an effective method of simulating piezoelectric PCs structure in which a square array of parallel cylindrical aluminum placed on a 128°YX LiNbO 3 substrate.

Hybrid integrated surface acoustic wave device structure

Abstract: The invention relates to a hybrid integrated surface acoustic wave device structure which is especially applicable to surface acoustic wave devices with high frequency, high electromechanical coupling coefficient and high integrated level The surface acoustic wave devices in the prior art have larger volume and greater weight and can not be applicable to weaponry with harsh requirements Aiming at solving the problems in the prior art, the invention provides a hybrid integrated surface acoustic wave device structure which is characterized in that a piezoelectric crystal is taken as a thin piezoelectric layer, the thickness of the thin piezoelectric layer is 10-80mum, an interdigital transducer is arranged on the upper surface of the piezoelectric crystal, and the interdigital transducer is called IDT for short; then a diamond-like thin film surface layer is arranged on the IDT, the thickness of the diamond-like thin film is 1-10mum; an integrated circuit layer is arranged on one surface of thick silicon; and finally the lower surface of the piezoelectric crystal is bonded with the upper surface of the thick silicon by adopting a low temperature bonding technology The hybrid integrated surface acoustic wave device structure provided by the invention can be used for reducing the volume of a device and simultaneously reducing the weight of the device

Surface acoustic wave label

Abstract: The invention belongs to the field of electronic information technology, and relates to a surface acoustic wave label which comprises the production of an interdigital transducer, at least one group of reflecting gates and an antenna on a piezoelectric substrate . The interdigital transducer comprises bus electrodes and interdigital electrodes, and the width of the buselectrodes is 40 micrometers. The width of the interdigital electrodes is 0.4 micrometers. The interval of two adjacent interdigital electrodes is 0.4 micrometers, and the length of the interdigital electrodes is 155 micrometers. The reflecting gates are open-circuited gates. The passive label provided by the invention has the advantages of passive, small size, strong anti-jamming capability, low transmission loss and long operation distance, and can work in adverse circumstances.

Electroacoustic transducer with periodic ferroelectric polarization produced on a micromachined vertical structure

Abstract: A piezoelectric and ferroelectric bulk wave transducer operating at a predetermined frequency includes a block of substrate, having a first thickness and in a first material, and a piezoelectric and ferroelectric transduction plate, having a length, a width and a second thickness, and in a second piezoelectric material, first and second metal electrodes covering the plate in the direction of the length thereof. The plate has first and second ferroelectric domains with alternating polarizations, distributed along the length of the plate according to a periodic pattern of pitch. The plate is attached perpendicularly to the block so that the width of the plate and the first thickness of the block are the same direction. The first and second material, the first thickness of the block, the length, the width, the second thickness, the pitch of the plate are configured for generating and trapping bulk waves at the operating frequency of the transducer, guided between both electrodes.

Cubic boron nitride piezoelectric film surface acoustic wave device and preparation method thereof

Abstract: The invention provides a cubic boron nitride piezoelectric film surface acoustic wave (SAW) device which is an IDT/c-BN/Al/ diamond multilayer film structure and is composed of a diamond substrate, an interface layer nano-aluminum film and a layer of nano-cubic boron nitride (c-BN) piezoelectric film formed on a surface of the nano-aluminum film. A preparation method of the device comprises the following steps: (1) employing a direct current magnetron sputtering method to deposit the nano-aluminum film on a nano-CVD diamond substrate surface; (2) employing a radio frequency magnetron sputtering method to deposit the nano-cubic boron nitride (c-BN) piezoelectric film on a surface of the nano-aluminum film; (3) preparing an interdigital transducer (IDT) on a surface of the nano-cubic boron nitride (c-BN) piezoelectric film. The surface acoustic wave device can satisfy application requirements of various fields like the surface acoustic wave (SAW) device with high frequency (4.8 GHz or more), a high electromechanical coupling coefficient, large power (more than 8 w), low propagation loss and a low frequency temperature coefficient, preparation technology is simple, application is easy, and popularization is facilitated.

Paper-based microfluid switch with acoustic surface wave as energy source

Abstract: The invention discloses a paper-based microfluid switch with an acoustic surface wave as an energy source. A paraffin micro-heating unit is arranged on a hydrophobic layer of a piezoelectric substrate, wherein the paraffin micro-heating unit comprises a PDMS (polydimethylsiloxane) microgroove, a PDMS fixing sheet which is connected to the top of the PDMS microgroove, and a metal microcell which is suspended inside the PDMS microgroove; and the bottom of the PDMS microgroove is tightly adhered and connected to the hydrophobic layer. By adopting the structure, the acoustic surface wave excited by an interdigital transducer on the piezoelectric substrate radiates a glycerine microfluid inside the PDMS microgroove, the temperature of the glycerine microfluid rises, the glycerine microfluid heats solid paraffin therein through the metal microcell with good heat-conducting property, the paraffin is expanded by heat, one end of a plastic foil above a micropore of a thin copper sheet ascends, and the plastic foil drives a third paper-based microchannel to ascend to enable the third paper-based microchannel to contact a first paper-based microchannel and a second paper-based microchannel respectively; and in the way that a switch is controlled to be switched on and off by virtue of expansion caused by heat and contraction caused by cold, the programmable characteristic of the switch is realized.