257 results about "Surface acoustic wave" patented technology

The invention provides an intelligent temperature control method and system for relieving stress of a glass annealing kiln. The method comprises the following steps: transmitting acoustic surface waves through a distributed sonic sensor to collect stress propagation data in glass, decoupling coupling characteristics of sound velocity and temperature, extracting a relaxation time constant, and generating a stress relaxation rate; performing time difference cross-correlation analysis to construct a stress propagation three-dimensional gradient field, establishing an incidence relation between the relaxation rate and the gradient field, and constructing a mapping strategy of the temperature set value and the relaxation rate according to the incidence relation; generating a dynamic temperature adjusting parameter and converting the dynamic temperature adjusting parameter into a heater power control signal; and dynamically adjusting a stress data feature extraction rule to match a real-time stress state according to the relevance between the gradient field update frequency and the temperature adjustment rate. According to the application, dynamic mutual optimization of the annealing stress elimination efficiency and the kiln temperature setting precision is realized, the glass residual stress is reduced, and the hidden danger of plate explosion is eliminated.

The invention discloses a method for detecting and analyzing the content of liquid flavor substances in a beverage, and belongs to the technical field of beverage quality detection. The method comprises the following steps: obtaining a flavor substance dielectric response signal and a surface acoustic wave propagation signal of a beverage sample, and carrying out correlation mapping integration to form a structured original data set; preprocessing data by adopting ensemble empirical mode decomposition, integrating features through a Bayesian network multi-source data fusion algorithm, and constructing an optimized content calculation model based on a gradient boosting tree algorithm; performing time sequence consistency and dimension matching verification on the data set, and inputting the data set into a model to generate a prediction result; and extracting a related content value, carrying out deviation analysis on the related content value and a preset standard range, calculating a signal feature contribution weight, and outputting a detection report containing standard judgment and deviation traceability. According to the method, the physicochemical characteristics of the flavor substances can be comprehensively represented, accurate prediction and deviation traceability are realized, the comprehensiveness, reliability and efficiency of detection are improved, and powerful support is provided for beverage quality control.

The invention provides a pipettor automatic calibration positioning and accuracy evaluation method based on photoelectric sensing, and relates to the technical field of pipettor calibration, and the method comprises the following steps: arranging an annular photoelectric sensor array to collect interference fringe phase difference, liquid level reflection light signals and surface acoustic wave signals, and adopting a five-step phase shift method to obtain a three-dimensional displacement vector; dynamic calibration is achieved through liquid level morphological parameter analysis in combination with adaptive Kalman filtering, numerical simulation is conducted on the liquid drop forming process through time-frequency analysis and a fluid mechanics model, and finally the accuracy is evaluated through adaptive fuzzy reasoning and Bayesian estimation. According to the invention, high-accuracy automatic calibration and evaluation of the pipettor are realized.

The application discloses a surface acoustic wave filter packaging structure and a packaging method thereof. The packaging structure comprises a substrate, solder resist layers arranged on the front surface of the substrate, filter chips and non-filter chips which are inverted on the front surface of the substrate and are arranged between the solder resist layers, and an injection molding layer covering the filter chips, the solder resist layers and the non-filter chips. The filter chips are uniformly provided with first protrusions on the side facing the substrate. The lower surface of the filter chip is overlapped with the upper surface of the adjacent solder resist layer, and a sealed cavity is formed between the filter chip, the solder resist layer and the substrate. The non-filter chips are uniformly provided with second protrusions on the side facing the substrate. A gap is left between the periphery of the non-filter chip and the adjacent solder resist layer, and the injection molding layer is filled below the non-filter chip. The application ensures the existence of the cavity at the bottom of the filter chip and protects the protrusions of the non-filter chip, thereby further improving the reliability of the product.

The invention provides a vector magnetic field detection method based on a surface acoustic wave magnetic field directivity model, and the method employs an external magnetic field to act on a magnetic sensitive film on a sound propagation path to generate a dynamic magnetoelastic coupling effect, modulates the propagation characteristics of surface acoustic waves, and carries out the decoupling of a sound signal, and obtains the magnetic field information. The response value of the sensor is influenced by the included angle between the direction of the external magnetic field and the anisotropic axis, so that the angle orientation of the sensor in the space and the size and direction of the magnetic field can be quantitatively calibrated by projecting the magnetic field to be measured in the space into a coordinate system of the sensor, and a surface acoustic wave magnetic field directivity model is constructed. The surface acoustic wave magnetic field sensing technology has the advantages of high sensitivity, quick response and the like, and the vector magnetic field detection method can realize the direction positioning function of a full-plane magnetic field and has important practical value in the application field of space vector magnetic field detection.

This invention provides a glass-based heterogeneous integrated structure with back vias and its fabrication method. Back vias are designed on a heterogeneous integrated wafer. The heterogeneous integrated wafer includes a glass substrate and a piezoelectric crystal layer, or at least one heterogeneous thin film layer is bonded between the glass substrate and the piezoelectric crystal layer. The back vias are blind vias and / or through-holes, with the blind vias etched to reach the piezoelectric crystal layer or any heterogeneous thin film layer. Filler metal is sputtered into the back vias. Before etching the front piezoelectric crystal layer, a surface acoustic wave (SAW) filter pattern can be fabricated on the complete surface of the glass-based heterogeneous integrated wafer with back vias. After etching the piezoelectric crystal layer, the bottom of the filler metal is exposed on the surface of the glass-based heterogeneous integrated wafer. The SAW filter and the filler metal are then interconnected through photolithography, evaporation or sputtering, electroplating, etc. The blind vias can be arranged into a folded inductor, connected to the front device layer through the through-holes. This invention features better device heat dissipation, improved package design and mass production capabilities, higher integration density, and higher device Q-value.

The utility model discloses a surface acoustic wave filter module packaging structure, which relates to the technical field of semiconductors and comprises a ceramic shell. According to the surface acoustic wave filter module packaging structure, a metal sealing cover is adopted for a surface acoustic wave filter, a tube shell is attached to the surface of an opening of a ceramic shell, packaging is conducted in a parallel sealing and welding mode, and parallel sealing and welding are divided into the three steps of vacuum baking, pre-welding and sealing and welding; in the vacuum baking process, a to-be-sealed device is heated and baked in a vacuum baking oven to remove water vapor and air, a user can take out a hotter packaging module from the vacuum baking oven through the cooperation of a related lifting appliance and a lifting hole due to the design of lug plates on the periphery of an opening of the ceramic shell, and in the subsequent pre-welding process, the packaging module can be taken out from the vacuum baking oven. And the metal sealing cover is embedded and matched with the inner wall of the opening of the ceramic shell through the bottom limiting strip, so that the accuracy of the mounting position of the metal sealing cover is guaranteed, the subsequent seal welding defect caused by the position deviation of the metal sealing cover is prevented, and the practicability is higher than that of the prior art.

The invention provides a surface acoustic wave filter and a manufacturing method thereof, and the surface acoustic wave filter comprises a substrate which is provided with a plurality of first grooves, and each first groove is internally provided with an interconnection layer; the plurality of resonators are arranged on the substrate; the plurality of resonators comprise spaced resonators and adjacent resonators, each resonator comprises a plurality of interdigital electrodes and bus bars connected with the interdigital electrodes, and the bus bars of the spaced resonators are electrically connected with the interconnection layer in the first groove so that the spaced resonators are electrically connected. By arranging the interconnection layer in the substrate, a traditional mode of forming a span bridge through dielectric layers such as Poly / Oxide and performing connection by means of PAD metal is replaced, the interlayer structure of the device is simplified, the production complexity is reduced, and the production period is effectively shortened.

The invention discloses a surface acoustic wave device and a radio frequency front end module, the surface acoustic wave device comprises a piezoelectric layer, a sound velocity layer and an interdigital electrode, and the interdigital electrode comprises a plurality of electrode fingers. The piezoelectric layer is provided with a first surface and a second surface which are oppositely arranged, the interdigital electrode is arranged on the first surface of the piezoelectric layer, and the sound velocity layer is arranged on the second surface of the piezoelectric layer; sound waves generated when the surface acoustic wave device works comprise surface acoustic waves and body waves; the surface acoustic wave device has a first characteristic depth, and the thickness of the piezoelectric layer is smaller than the first characteristic depth; wherein the first characteristic depth is related to the midline distance between two adjacent electrode fingers of the interdigital electrode, the bulk wave sound velocity of the piezoelectric crystal in the x direction and the working frequency. The sound velocity layer is directly arranged below the piezoelectric layer, the thickness of the piezoelectric layer is limited to be smaller than the first characteristic depth, and the thickness of the piezoelectric layer is reasonably reduced, so that the sound velocity of the surface wave is obviously improved or reduced, and meanwhile, the influence on the effects of other functional layers is avoided.

This invention provides a surface acoustic wave (SAW) filter, comprising a piezoelectric layer and interdigitated electrodes. The interdigitated electrodes are disposed on the piezoelectric layer and include at least a first metal layer and a second metal layer stacked together. The first metal layer is made of platinum or an alloy with platinum as the main component, and the second metal layer is made of aluminum or an alloy with aluminum as the main component. By setting the material of the second metal layer to aluminum or an alloy with aluminum as the main component, the uniformity of metal coverage of the electrode structure can be effectively improved, avoiding excessive local resistance or structural defects caused by poor coverage. Setting the material of the first metal layer to platinum or an alloy with platinum as the main component provides reliable support for the second metal layer, reducing the risk of deformation or corrosion of the aluminum layer in subsequent processes. By using a stacked structure of two complementary materials for the interdigitated electrodes, both structural miniaturization and improved overall electrical performance and structural reliability of the interdigitated electrodes are achieved.

The invention relates to the technical field of acoustic wave device application and biological tissue engineering, in particular to a method for constructing a multi-component heterogeneous fiber structure under the assistance of acoustic tweezers. According to the method, an acoustic tweezers technology and a microfluidic spinning technology are combined, an electric signal is converted into an acoustic surface wave through the piezoelectric effect of a piezoelectric material, and a beam-shaped acoustic standing wave field is formed in a microchannel of a specific structure; different target cells form a stable fiber configuration under the interaction of microchannel limitation and acoustic radiation force, and spatial precise classification and arrangement of multiple types of cells are realized. The low-temperature-sensitive hydrogel is introduced in the cell injection process, and the fiber scaffold is formed after ultraviolet curing, so that the fiber structure of the cells is still maintained after the sound field is removed. The cells treated by the surface acoustic wave can form a complex three-dimensional bionic tissue structure more easily, and the cell viability is remarkably improved. Various fiber structures can be formed by regulating and controlling sound field parameters, and great potential is shown in the field of in-vitro barrier model construction.

The application discloses a three-dimensional ferroelectric material based on two-dimensional ice stacking and preparation and application thereof, and belongs to the technical field of ferroelectric materials and multifunctional devices. The material is a three-dimensional periodic crystal structure of monoclinic P21 space group, water molecules in the material form a completely saturated network through hydrogen bonds, and there is no suspended hydrogen; interlayers are coupled through van der Waals force to form a multi-level cooperative ferroelectric sequence of "in-plane hydrogen bond ferroelectric + interlayer van der Waals ferroelectric". The material has the characteristics of a wide-bandgap semiconductor (band gap 5-6 eV), extreme anisotropic mechanical properties (Z-axis Young's modulus 48.6 GPa, Eyx=0.973), moderate bulk modulus (12.23 GPa), good acoustic performance (sound velocity 2638 m / s) and extremely high pressure stability (0-3000 GPa structure is complete, 1190 GPa metalization transition). The material can be widely applied in the fields of X-ray optical devices, ferroelectric memories, deep ultraviolet photoelectric detectors, extreme high-pressure sensors, directional stress sensors, mechanical logic devices, surface acoustic wave filters, multifunctional integrated microsystems and multi-parameter composite sensing networks, and opens up a new direction for pure water-based functional materials.

The invention relates to a DMS type filter and a filtering device, the DMS type filter comprises reflecting gratings and a plurality of IDTs arranged between the reflecting gratings, and each IDT is arranged along the propagation direction of surface acoustic waves; each IDT comprises a plurality of spacing intervals, and each spacing interval is provided with interdigitals which are arranged along the propagation direction of the surface acoustic wave and are sequentially connected end to end; wherein each IDT comprises a main spacing area and a plurality of spacing adjusting areas, the spacing of the interdigitals in the main spacing area is consistent, the spacing of the adjacent interdigitals in each spacing adjusting area monotonically changes in the form of a quadratic power function along the direction far away from the main spacing area, and the variation amplitudes of the spacing of the adjacent interdigitals in different spacing adjusting areas are different. By adjusting the distance between the interdigitals one by one, the design freedom degree is remarkably improved, and therefore the purposes of reducing insertion loss, improving the standing-wave ratio, expanding the bandwidth and the like are achieved so as to adapt to different use scenes, and the application range is widened.

To provide a superconducting device implemented with a surface acoustic wave resonator and a superconducting microwave resonator that are coupled to a Josephson ring modulator, and methods of applications thereof.SOLUTION: A method comprises: receiving, by a microwave Josephson mixer and from a superconducting surface acoustic wave resonator of a superconducting device, a surface acoustic wave signal that comprises one or more phonons that resonate at a first frequency; receiving, by the microwave Josephson mixer and from a superconducting microwave resonator of the superconducting device, a microwave signal that comprises one or more photons that can resonate at a second frequency; and mixing, by the microwave Josephson mixer, the surface acoustic wave signal and the microwave signal on the basis of a microwave control signal received from a microwave source operatively coupled to the microwave Josephson mixer.SELECTED DRAWING: Figure 8

The invention relates to a sensor unit (20) for detecting forces and their directions in the XY plane, comprising at least two sensors distributed on a mechanical measuring body (10). According to the invention, the at least two sensors are surface acoustic wave (SAW) sensors (24), wherein one or more milled grooves (22) are formed in the surface of the measuring body (10) for controlling the propagation of surface acoustic waves, and wherein the SAW sensors (24) are arranged on the measuring body (10) such that a precise determination of the direction and magnitude of the acting forces in the XY plane is enabled.

The invention discloses a device capable of localizing a surface acoustic wave center. The device comprises a device body and hard boundaries arranged on the upper surface and the lower surface of the device body. The device body comprises a plurality of primitive cells arrayed in the Z direction and an A-layer assembly arranged on the lower surface of the bottommost primitive cell. Each primitive cell comprises a B-A coupling layer assembly, a B-layer assembly, an A-B coupling layer assembly and an A-layer assembly which are sequentially stacked from bottom to top; pi phase difference delay exists between the A-layer assembly and the B-layer assembly. The primitive cell is constructed to be composed of a plurality of non-periodic structural units; the structural unit comprises a B-A coupling unit and a structure B which are arranged from bottom to top, the coupling strength of the A-B coupling unit and the coupling strength of the structure A are different, and the coupling strength of the A-B coupling unit and the coupling strength of the B-A coupling unit are different; rotation parameters are introduced into an X-Y plane in a three-dimensional space where the device is located, so that the primitive cell center has a vortex center, and the period of the primitive cell in the Z direction is of a limited size. Through the device, a zero-dimensional topological angular state can be formed, and surface acoustic waves are localized in the center of the top surface of the device.

A surface acoustic wave (SAW) wafer-level package is disclosed, comprising: a substrate; an interdigitated transducer (IDT) formed on the substrate; a sidewall formed on the substrate along the periphery of the IDT; a cover formed on the sidewall and above the IDT to form a hollow portion with the sidewall above the IDT; a connecting electrode formed on the substrate, electrically connected to the IDT and extending outward from the periphery of the sidewall; a connecting terminal electrically connected to the portion of the connecting electrode extending outward from the periphery of the sidewall, formed as an outer surface covering the sidewall and a surface and a portion of the top surface of the cover, and having a top surface formed above the top surface of the cover; and an organic solderable corrosion protectant (OSP) coating formed at least on the top surface of the connecting terminal.

A surface acoustic wave (SAW) device includes: a piezoelectric layer; an interdigitated electrode structure located on the piezoelectric layer; a wiring layer located on the piezoelectric layer and electrically connected to the interdigitated electrode structure; an interconnect layer located on the wiring layer; bumps located on the interconnect layer; and a metallization structure located between the interconnect layer and the bumps, electrically connecting the interconnect layer and the bumps and preventing material from the bumps from penetrating into the interconnect layer. The metallization structure on the interconnect layer prevents the bumps from directly contacting the interconnect layer, instead connecting them electrically through the metallization structure. This prevents the material of the bumps from fusing with the material of the interconnect layer and intruding into the device, thus preventing semiconductor device failure and improving the performance of the semiconductor device. Furthermore, the metallization structure's location between the bumps and the interconnect layer enhances the adhesion between the bumps and the interconnect layer.

The application provides a wafer-level surface acoustic wave filter and a radio frequency module chip, and the wafer-level surface acoustic wave filter comprises a substrate, a finger assembly, a dam, a cover plate, a metal column, a metal common ground layer and a solder ball, wherein the finger assembly comprises fingers, bus bars and metal plates formed on the substrate by photoetching and silk printing; the dam is fixed to the substrate; the cover plate is arranged on the dam and is provided with a plurality of through holes; the metal column is fixed to the substrate and is inserted into a corresponding through hole; the metal common ground layer is arranged on the side of the cover plate away from the finger assembly, and part of the metal columns are electrically connected with the metal common ground layer to form a common ground signal end, and the other part of the metal columns are insulated from the metal common ground layer to form a signal input end and a signal output end; and the solder ball is arranged on the end of each metal column away from the substrate. The wafer-level surface acoustic wave filter has simple structure, good wear resistance and high WLP packaging reliability.

The invention provides a surface acoustic wave device structure and device. The surface acoustic wave device structure comprises a substrate, a piezoelectric layer formed on the substrate 100 and an IDT electrode formed on the surface of the piezoelectric layer. The piezoelectric layer is etched into a first surface and a second surface which have a height difference, and the electrode fingers of the IDT electrode extend along the second direction and partially cover the first surface. The height difference between the first surface and the second surface is regulated and controlled, and the difference value of the height difference does not exceed the thickness of the electrode fingers, so that the local thickness distribution of the piezoelectric layer is changed, the purposes of adjusting the intensity distribution of the surface acoustic wave energy and accurately adjusting the propagation speed of the surface acoustic wave are achieved, and the flexible and smooth adjustment of the electromechanical coupling coefficient (K2) is realized. Meanwhile, the structure mutation formed by the height difference can optimize the reflection path of the surface acoustic wave, and in combination with the partial coverage design of the electrode fingers, the transverse parasitic mode can be inhibited.

The invention discloses a high-rectangularity surface acoustic wave device structure and a method for improving rectangularity, a surface acoustic wave device sequentially comprises a substrate layer, a piezoelectric film layer and an electrode structure layer from bottom to top, the electrode structure layer is composed of a plurality of independent electrode structures, and at least one electrode structure rotates by a certain angle relative to the crystal orientation of the substrate. And the included angle theta between the electrode structure and the crystal orientation of the substrate is greater than 0 degree. By optimizing the rotation angle of the electrode structure, the propagation characteristic of the surface acoustic wave can be effectively controlled, the rectangularity of the device is remarkably improved, the design of the high-rectangularity surface acoustic wave device is realized, the design requirements of Beidou, navigation and the like on the high-rectangularity surface acoustic wave filter are met, the adopted preparation process has good feasibility and compatibility, and the application prospect is wide. The method is suitable for large-scale manufacturing and industrial popularization.

The invention discloses a surface acoustic wave filter multi-dimensional defect identification system and method based on machine learning, and relates to the field of multi-dimensional defect identification, and the system comprises a data acquisition and processing module, a feature extraction module, a defect analysis module, a defect verification module and a defect evaluation module. The method comprises the following steps: acquiring multi-dimensional data of a surface wave filter, and performing time synchronization and processing analysis to obtain a processed device surface microscopic image, enhanced device three-dimensional morphology data and an enhanced device S parameter frequency spectrum; performing electrode geometric feature extraction and spectrum anomaly detection to obtain a first geometric feature vector and a second spectrum feature vector; performing defect candidate analysis to obtain a defect candidate region set; and feature relation graph construction and physical verification analysis are carried out on each defect candidate region to obtain defect parameters after physical verification, defect classification, positioning and severity evaluation are carried out to obtain a filter defect multi-dimensional evaluation result, and the physical position and geometric morphology of the defect can be accurately positioned.

A surface acoustic wave resonance device comprises an interdigital electrode structure which is located on the surface of a piezoelectric layer, has a first thickness and comprises a plurality of first electrode strips and a plurality of second electrode strips; the first dielectric layer is positioned on the piezoelectric layer; the first load part and the second load part are located on the first dielectric layer, the first load part and the second load part are located at the two opposite ends of the overlapping area in the first direction respectively, a first distance is formed between the first load part and the interdigital electrode structure, and a second distance is formed between the second load part and the interdigital electrode structure; the ratio of the first distance to the first thickness is greater than 0.5, and the ratio of the second distance to the first thickness is greater than 0.5, so that the surface acoustic wave resonance device is excited to form a piston mode, a high-order transverse parasitic mode is effectively inhibited, and electrostatic breakdown caused by too small first distance or too small second distance is avoided.

The invention belongs to the technical field of temperature detection, and particularly relates to a surface acoustic wave double-frequency compensation and radio frequency activation electrical equipment passive wireless temperature measurement system, which comprises a main controller module, and is characterized in that the main controller module is internally provided with an edge calculation module used for operating an LSTM model, predicting a temperature trend and correcting interference; the multi-mode fusion module is used for fusing multi-sensor data and dynamically correcting temperature readings through environmental parameters; the remote reporting module is used for accelerating edge calculation and ensuring that a high-temperature event signal is preferentially uploaded in combination with an LPWAN protocol; and the decision linkage module is used for optimizing linkage of the condensed aerosol fire extinguishing device and preferentially processing a high-risk area based on real-time data. According to the invention, a temperature rise trend prediction system with response time less than 5 seconds can be constructed, high precision and low delay of temperature reading in a complex environment can be realized, the uploading efficiency of high-temperature alarm information is optimized, and the response speed of a high-risk area is improved.

An aerosol-generator for an aerosol-generating device is provided, including: a surface acoustic wave atomiser including: a substrate including an active surface defining an atomisation region, and at least one transducer positioned on the active surface to generate surface acoustic waves for defining an acoustic wavefront on the active surface; and a supply element arranged to supply a liquid aerosol-forming substrate to the atomisation region so that liquid aerosol-forming substrate in the atomisation region defines an interface between the active surface, the liquid aerosol-forming substrate, and the atmosphere, in which the at least one transducer and the supply element are configured so that a shape of the acoustic wavefront at the interface corresponds to a shape of at least part of the interface. An aerosol-generating device including the aerosol-generator is also provided.

This invention discloses a surface acoustic wave (SAW) filter. It includes: a piezoelectric layer; a plurality of resonators disposed on one side of the piezoelectric layer; and an attenuation structure disposed between two adjacent resonators. The attenuation structure includes at least an elastic wave attenuation material layer, the elastic modulus E1 of which satisfies: E1 ≤ 10 GPa. By including an elastic wave attenuation material layer with an elastic modulus lower than 10 GPa in the attenuation structure between two adjacent resonators, this invention allows the elastic waves leaking from the resonators to be rapidly attenuated within the attenuation structure. This prevents SAW from propagating outside the resonators through the reflector grating or through the gap-pseudo-busbar, thus preventing SAW coupling between adjacent resonators. Furthermore, the fabrication process of the attenuation structure can be the same as existing resonator fabrication processes, allowing for shared equipment, and is simple, easy to implement, and low in cost.

The application provides an overhead cable joint live temperature measuring device and a mounting method, which comprises a surface acoustic wave temperature sensor mounted on the surface of an overhead cable joint through an arc-shaped fixing member and a mounting thimble; a monitoring distribution box, which is provided with a hanger for being connected with a hoop buckle; an insulating rod tool, which comprises an insulating rod main body and a threaded hole arranged on the top of the insulating rod main body, and the threaded hole can alternatively connect a sensor mounting bracket or a distribution box mounting bracket, so as to respectively realize the mounting of the sensor on the overhead cable joint and the mounting of the monitoring distribution box on a tower pole supporting the overhead cable in a live state; the surface acoustic wave temperature sensor realizes passive temperature collection through a reflection delay line structure, and transmits temperature information to the monitoring distribution box through a radio frequency signal of a unique frequency band. The application can realize the quick mounting and dismounting of the overhead line joint temperature measurement in a live state, and has the advantages of convenient installation and strong system independence.

Systems, methods, and other embodiments described herein relate to estimating direction of a surface acoustic wave (SAW) using temperature measurements from multiple resonators. In one embodiment, a method includes measuring temperatures of multiple resonators that are excited by a SAW using a sensor. The method also includes searching an angle from a temperature ratio of the multiple resonators using the temperatures. The method also includes estimating a direction of the SAW using the angle.

The application discloses a residual stress detection method based on chirp electromagnetic surface acoustic wave. Although the existing variable interval coil structure can expand the working frequency band of the sensor, the excitation ability of the low frequency component is limited, and it is difficult to meet the stress detection requirements of large thickness components. The electromagnetic acoustic sensor structure is designed, the width of the coil is continuously changed along the ultrasonic surface wave propagation direction, the wide frequency excitation of the chirp surface wave signal is realized, especially the excitation and propagation effect of the low frequency component is enhanced, so that the signal-to-noise ratio and detection accuracy after the signal matched filtering are significantly improved. The sensor utilizes the characteristics that the penetration depth of the ultrasonic surface wave changes with the frequency, realizes the layered detection of the multi-level residual stress in the material through the chirp signal, can cover multiple frequency ranges to adapt to components with different thicknesses, thereby avoiding the problem that the traditional fixed frequency or variable interval sensor needs to be frequently replaced. The method has high detection accuracy, wide detection range and high detection efficiency, and is suitable for nondestructive residual stress evaluation of metal components and engineering structure health monitoring.

Aspects of the disclosure relate to an apparatus. The apparatus can include a piezoelectric layer including a surface along a surface plane. A plurality of piezoelectric structures extend from the surface in a direction orthogonal to the surface plane. The apparatus can include an electrode layer comprising an electrode disposed on the plurality of piezoelectric structures. wherein the electrode extends along an axis parallel to the surface plane to form at least one finger of an interdigitated transducer (IDT). In some cases, a surface acoustic wave (SAW) filter includes the IDT.