CN110504943B - Interdigital transducer array and manufacturing method thereof - Google Patents
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- CN110504943B CN110504943B CN201910789049.2A CN201910789049A CN110504943B CN 110504943 B CN110504943 B CN 110504943B CN 201910789049 A CN201910789049 A CN 201910789049A CN 110504943 B CN110504943 B CN 110504943B
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
- H03H9/14544—Transducers of particular shape or position
- H03H9/14547—Fan shaped; Tilted; Shifted; Slanted; Tapered; Arched; Stepped finger transducers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
- H03H2003/026—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks being of the tuning fork type
Abstract
The invention discloses an interdigital transducer array and a manufacturing method thereof, wherein the interdigital transducer array comprises a polyvinylidene fluoride substrate and N trapezoidal interdigital electrode array elements; the polyvinylidene fluoride substrate is disc-shaped, and a plurality of trapezoidal interdigital electrode array elements are uniformly distributed on the surface of the polyvinylidene fluoride substrate along the circumferential direction by taking the circle center of the polyvinylidene fluoride substrate as the center; the anode interdigital electrode of the trapezoidal interdigital electrode array element comprises an anode external connection end and a plurality of mutually spaced positive electrodes, and the cathode interdigital electrode of the trapezoidal interdigital electrode array element comprises a cathode external connection end and a plurality of mutually spaced negative electrodes; a plurality of positive electrodes and a plurality of negative electrodes in each trapezoidal interdigital electrode array element are alternately arranged at intervals; every two adjacent trapezoidal interdigital electrode array elements share a positive electrode external connection end, and every two adjacent trapezoidal interdigital electrode array elements share a negative electrode external connection end. The invention has the advantages of wide frequency band, low loss, multi-directional transmission and reception, and improves the damage detection efficiency.
Description
Technical Field
The invention relates to the technical field of interdigital transducers, in particular to an interdigital transducer array and a manufacturing method thereof.
Background
In the methods and related technologies applicable to Monitoring of large-area Structural Health (SHM), many advanced signal processing methods still have many defects such as large man-made interference factors and narrow application ranges. The transducer device for electro-acoustic conversion has become a key component in the SHM system due to its unique function of transmitting structural security information. The existing structural health monitoring system always has the requirement of further improving the detection sensitivity and precision, and the flexible interdigital transducer which can be used for large-area composite materials and has the functions of multidirectional transmitting and receiving, wide frequency and mode selection can solve the key technical obstacle for realizing real-time quick SHM.
The existing ultrasonic guided wave-based SHM system usually adopts embedded or pasted ultrasonic transducer units to construct a driving/sensing array with a certain spatial distribution form or a sparsely distributed sensing network, and can be used for overcoming the problems of impedance attenuation, low signal response and the like in a large-area plate or composite material structure. The sparse distribution sensing network detects the local damage of the structure according to the transit time information of the guided wave signals among the sensing units, and the damage imaging positioning precision of the sparse distribution sensing network greatly depends on the arrangement scheme of the sparse sensor.
In terms of the structural design of the Transducer, the Interdigital structure of an Interdigital Transducer (IDT) is the most basic form for generating directional guided waves in an SHM system, however, the IDT design in the prior art still has many disadvantages, such as narrow frequency bandwidth and single directivity, and in order to adapt to smaller damage detection scale, a smart Transducer structural design is required to increase the bandwidth so as to realize multidirectional driving and sensing.
Interdigital transducers were first proposed by hypodo et al as an extension of the building block design method in 1968. In 1973, daniel and de Klerk later compared the advantages of trapezoidal interdigital transducers and chirps with the filter structure of the apodized passband, indicating that interdigital transducers can be used in bandpass applications. From 1982 to 1987, campbell described detailed procedures for designing broadband linear phase filters, and experiments were conducted with 70MHz 50% bandwidth filters on yz-lithium niobate, effectively suppressing side lobes of >35db while increasing the frequency response.
In view of the development of the application of the integrated IDT, the existing rectangular IDT has already been maturely applied to the saw device and has been greatly developed, and the rectangular IDT is also gradually applied to the damage detection, which has the largest frequency response at the center frequency, so that the center frequency is generally designed to be the excitation frequency. Along with the development of structural health monitoring, the engineering structure is more and more complicated, the IDT loss is required to be lower and lower, and the performance is continuously improved. The existing rectangular IDT is narrow in line width and cannot meet the repeated stress action of higher and higher frequencies and higher power, so that the research on the IDT with wide frequency band, low loss and high performance is very important for structural health monitoring. However, for the trapezoidal interdigital transducer, the design of the filter is mainly used, and the application of the filter to damage detection is not mature. Because the interdigital structure of the interdigital transducer is the most basic form for generating directional guided waves in the SHM system in terms of the structural design of the transducer, however, there are still many disadvantages in the IDT design in the prior art, such as narrow frequency bandwidth and single directivity.
Disclosure of Invention
The invention aims to provide an interdigital transducer array and a manufacturing method thereof, which have the advantages of wide frequency band, low loss, multi-directional transmission and receiving and improve the damage detection efficiency.
In order to achieve the purpose, the invention provides the following scheme:
an interdigital transducer array, comprising: the polyvinylidene fluoride substrate and N trapezoidal interdigital electrode array elements, wherein N is an integer greater than 3; the polyvinylidene fluoride substrate is disc-shaped, and a plurality of trapezoidal interdigital electrode array elements are uniformly distributed on the surface of the polyvinylidene fluoride substrate along the circumferential direction by taking the circle center of the polyvinylidene fluoride substrate as the center;
the anode interdigital electrode of the trapezoidal interdigital electrode array element comprises an anode external connection end and a plurality of mutually spaced positive electrodes, one end of each positive electrode is connected with the anode external connection end, the positive electrodes are coplanar, the cathode interdigital electrode of the trapezoidal interdigital electrode array element comprises a cathode external connection end and a plurality of mutually spaced negative electrodes, one end of each negative electrode is connected with the cathode external connection end, and the negative electrodes are coplanar; a plurality of positive electrodes and a plurality of negative electrodes in each trapezoidal interdigital electrode array element are alternately arranged at intervals;
and each two adjacent trapezoidal interdigital electrode array elements share one positive electrode external connection end, and each two adjacent trapezoidal interdigital electrode array elements share one negative electrode external connection end.
Optionally, the width of the positive electrode and the width of the negative electrode in the trapezoidal interdigital electrode array element gradually decrease from the positive external connection end to the negative external connection end.
Optionally, the trapezoidal interdigital electrode array element is made of gold powder.
Optionally, the thickness of the polyvinylidene fluoride substrate is 0.3mm.
The invention also provides a manufacturing method of the interdigital transducer, which is characterized by comprising the following steps:
polarizing a polyvinylidene fluoride material along the thickness direction to obtain a polyvinylidene fluoride substrate, wherein the polyvinylidene fluoride substrate is disc-shaped;
the polyvinylidene fluoride substrate is used as a bottom surface, a graph of N trapezoidal interdigital electrode array elements is designed on the bottom surface, N is an integer larger than 3, and the plurality of trapezoidal interdigital electrode array elements are uniformly distributed on the surface of the bottom surface along the circumferential direction by taking the circle center of the bottom surface as the center; the anode interdigital electrode of the trapezoidal interdigital electrode array element comprises an anode external connection end and a plurality of mutually spaced anode electrodes, one ends of the anode electrodes are all connected with the anode external connection end, the anode electrodes are coplanar, the cathode interdigital electrode of the trapezoidal interdigital electrode array element comprises a cathode external connection end and a plurality of mutually spaced cathode electrodes, one ends of the cathode electrodes are all connected with the cathode external connection end, and the cathode electrodes are coplanar; a plurality of positive electrodes and a plurality of negative electrodes in each trapezoidal interdigital electrode array element are alternately arranged at intervals; each two adjacent trapezoidal interdigital electrode array elements share one positive electrode external connection end, and each two adjacent trapezoidal interdigital electrode array elements share one negative electrode external connection end;
depositing N trapezoidal interdigital electrode array elements on the surface of the polyvinylidene fluoride substrate by adopting a metal spraying process according to the designed N trapezoidal interdigital electrode array element graphs to obtain a polyvinylidene fluoride-based trapezoidal interdigital transducer array;
and packaging the polyvinylidene fluoride-based trapezoidal interdigital transducer array by adopting a polymer protective layer.
Optionally, the width of the positive electrode and the width of the negative electrode in the trapezoidal interdigital electrode array element gradually decrease from the positive electrode external connection end to the negative electrode external connection end.
Optionally, the trapezoidal interdigital electrode array element is made of gold powder.
Optionally, the thickness of the polyvinylidene fluoride substrate is 0.3mm.
According to the invention content provided by the invention, the invention discloses the following technical effects:
the invention provides an interdigital transducer array and a manufacturing method thereof, wherein the interdigital transducer array comprises the following components: the polyvinylidene fluoride substrate is disc-shaped, and a plurality of trapezoidal interdigital electrode array elements are uniformly distributed on the surface of the polyvinylidene fluoride substrate along the circumferential direction by taking the circle center of the polyvinylidene fluoride substrate as the center; a plurality of positive electrodes and a plurality of negative electrodes in each trapezoidal interdigital electrode array element are alternately arranged at intervals; the two adjacent trapezoidal interdigital electrode array elements share one anode external connection end, and the two adjacent trapezoidal interdigital electrode array elements share one cathode external connection end, so that the device has the characteristics of wide frequency band, low loss, multi-directional emission and receiving, can detect materials with different structures, and improves the damage detection efficiency.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an interdigital transducer array according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a single trapezoidal interdigital electrode array element in an interdigital transducer array according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of the phase velocity dispersion curve of the aluminum plate and the IDT electrode design according to the embodiment of the present invention;
FIG. 4 is a graph of the change in unit voltage strain of trapezoidal interdigital transducers with different electrode widths as a function of substrate thickness in accordance with embodiments of the present invention;
FIG. 5 is a graph of the frequency response of an interdigital transducer array, in accordance with embodiments of the present invention;
FIG. 6 is a frequency response diagram of a conventional IDT according to an embodiment of the present invention;
FIG. 7 is a graph showing displacement amplitude response of Lamb waves generated by excitation of IDT and PZT in accordance with an embodiment of the present invention;
fig. 8 is a flow chart illustrating a method for manufacturing an interdigital transducer according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The invention aims to provide an interdigital transducer array and a manufacturing method thereof, which have the advantages of wide frequency band, low loss, multi-directional transmission and receiving and improve the damage detection efficiency.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic structural diagram of an interdigital transducer array according to an embodiment of the present invention, and fig. 2 is a schematic structural diagram of a single trapezoidal interdigital electrode array element in an interdigital transducer array according to an embodiment of the present invention, as shown in fig. 1-2, the interdigital transducer array includes: polyvinylidene fluoride { Poly (vinylidene fluoride) PVDF } substrate 1 and N trapezoidal interdigital electrode array elements, wherein N is an integer more than 3; the polyvinylidene fluoride substrate is disc-shaped, and a plurality of trapezoidal interdigital electrode array elements are uniformly distributed on the surface of the polyvinylidene fluoride substrate 1 along the circumferential direction by taking the circle center of the polyvinylidene fluoride substrate 1 as the center; the polyvinylidene fluoride substrate 1 is a polyvinylidene fluoride piezoelectric film substrate, the trapezoidal interdigital electrode array elements are made of gold powder, and the polyvinylidene fluoride substrate 1 has good flexibility, so that the interdigital transducer array disclosed by the invention is suitable for the surface of an irregular complex structure, and even is directly embedded into a host structure for damage detection. Meanwhile, the polyvinylidene fluoride substrate 1 implemented by the invention has the excellent characteristics of high elastic density, ultrashort reaction time, high electromechanical coupling efficiency, light weight and the like, adopts the polyvinylidene fluoride piezoelectric film as the substrate, is used for improving the structural detection sensitivity, enhances the energy in the polarization direction, and is beneficial to improving the damage detection rate.
The anode interdigital electrode 2 of the trapezoidal interdigital electrode array element comprises an anode external connection end and 4 positive electrodes which are mutually spaced, one ends of the 4 positive electrodes are all connected with the anode external connection end, the 4 positive electrodes are coplanar, the cathode interdigital electrode 3 of the trapezoidal interdigital electrode array element comprises a cathode external connection end and 4 negative electrodes which are mutually spaced, one ends of the 4 negative electrodes are all connected with the cathode external connection end, and the 4 negative electrodes are coplanar; the 4 positive electrodes and the 4 negative electrodes are all in the shape of an arc with a width; 4 positive electrodes and 4 negative electrodes in each trapezoidal interdigital electrode array element are alternately arranged at intervals; every two adjacent trapezoidal interdigital electrode array elements share a positive electrode external connection end, and every two adjacent trapezoidal interdigital electrode array elements share a negative electrode external connection end. The straight line where the anode external connection end or the cathode external connection end of each two adjacent trapezoidal interdigital electrode array elements is located intersects the center of the polyvinylidene fluoride substrate 1, and each two adjacent trapezoidal interdigital electrode array elements are symmetrical about the anode external connection end or the cathode external connection end.
In this embodiment, in order to ensure the electrode processing precision, the minimum width and the maximum width of the positive electrode of the positive interdigital electrode 2 are 0.25mm and 0.5mm, respectively, the minimum width and the maximum width of the negative electrode of the negative interdigital electrode 3 are 0.25mm and 0.5mm, the width of the positive electrode and the width of the negative electrode in the trapezoidal interdigital electrode array element gradually decrease from the positive external connection end to the negative external connection end, as shown in fig. 2, a distance d 'between two adjacent positive electrodes and negative electrodes, also referred to as an electrode distance d', gradually decreases from the positive external connection end to the negative external connection end, and the maximum distance d 'and the minimum distance d' are 0.5mm and 0.25mm, respectively. The change of the electrode spacing leads to the change of frequency, so that the frequency bandwidth has designability, the characteristic of IDT broadband is realized, the guided wave mode selection is realized, when the IDT broadband is used for guided wave excitation and receiving, the detection transducer does not need to be replaced according to the change of structural materials, and the identification rate of effective signals in engineering structure damage detection is improved.
FIG. 3 is a schematic diagram of the phase velocity dispersion curve and IDT electrode design of an aluminum plate, as shown in FIG. 3, lamb wave, i.e. Lamb wave, has multi-modal and frequency dispersion characteristics, and in the actual nondestructive test, a single mode is required to improve the precision, so that the frequency and thickness product designed in the aluminum plate does not exceed A 1 The cut-off frequency of (c). The symmetric pattern in FIG. 3 includes the curve S 0 Curve S 1 And curve S 2 The antisymmetric mode includes a curve A 0 Curve A 1 And curve A 2 The wavelength λ of any Lamb mode is given by:
wherein c is p Is the phase velocity, f is the frequency, then can also be written as
d is the plate thickness, the trajectory of the constant λ/d is a straight line passing through the origin on the phase velocity dispersion curve. As shown in fig. 3, the point at which the IDT designed for that wavelength intersects dispersion curves of different modes is a point that can be used to design the excited mode. λ/d =1,2,3,4,5 corresponding to A, respectively 0 The curves intersect at different points, the product of frequency and thickness corresponding to the abscissa is 0.3MHz-mm at λ = 5; at λ =1, the frequency-thickness product corresponding to the abscissa is 2.8MHz-mm. Assuming an aluminum plate thickness of 1mm, λ =1 corresponds to a frequency of 0.3MHz and λ =5 corresponds to a frequency of 2.8MHz. In the IDT, in order to make the superposition effect the best, the interdigital electrode has a period length equal to one wavelength λ, that is, the width of a pair of interdigital electrodes (a pair of interdigital electrodes refers to an adjacent positive electrode and a negative electrode) is equal to the wavelength λ, so that the single electrode width =1/2 electrode pitch = λ/4. At this time λ =1,2,3,4,5mm corresponds to the electrode width of the uniform IDT being 0.25mm,0.5mm,0.75mm,1mm,1.25mm. Therefore, in the present embodiment, the minimum width of the negative electrode in the interdigital electrode 3 for the negative electrode and the minimum distance between the positive electrode and the negative electrode are both selected to be 0.25mm.
The optimization design calculation of the electrode size is carried out by COMSOL Multiphysics software, and the calculation result is shown in FIG. 4. In the figure, 0.25mm represented by a square icon represents a rectangular IDT having an electrode width and an electrode pitch of 0.25mm, and the thickness of the substrate represented by the abscissa is from 0.1mm to 0.6mm. As can be seen from fig. 4, in the PVDF substrate, the strain value of the rectangular IDT per unit voltage is still large relative to the values of the other trapezoidal interdigital transducers. In the trapezoidal interdigital transducers, the unit voltage strain value initially increases along with the increase of the thickness of the substrate, and starts to decrease when reaching a maximum value and tends to be stable. And, in the case of the same substrate thickness, the smaller the value of the bottom end positive electrode dimension a, the larger the unit voltage strain value. Therefore, in the present invention, the unit voltage strain value is the largest when the left maximum positive electrode width a =0.5mm and the substrate thickness h =0.3 mm.
Fig. 5 is a graph showing the frequency response of an interdigital transducer array of the present invention. The frequency bandwidth can be represented by the formula:
wherein λ min 、λ max The period across the positive or negative electrode respectively, equals 2 times the electrode spacing and 4 times the electrode width, V represents the wave velocity. In addition, as the frequency bandwidth increases, the frequency response curve shows larger and larger side lobes, and the broadband shows a downward trend of non-uniformity, which indicates that the increase of the frequency bandwidth is not infinite and cannot increase the bandwidth at will. As is apparent from comparison between fig. 5 and 6, the frequency response range of the interdigital transducer array is significantly enlarged, so Lamb waves at different frequencies can be excited in practical application, and more working conditions are met.
Fig. 7 is a graph showing a displacement amplitude response of Lamb waves generated by IDT and piezoelectric ceramic (piezoelectric ceramic PZT) Zirconate Titanate (PZT). It can be seen that Lamb wave energy generated by IDT excitation is relatively more concentrated and the amplitude response is greatly enhanced compared to Lamb waves generated by conventional PZT excitation.
The interdigital transducer array designed by the invention has the advantages that the amplitude in the horizontal direction is the largest, the amplitude in the vertical direction is very small, and the left and the right are symmetrical when exciting signals. Also, when acting as a sensor, it is most sensitive to excitation in the horizontal direction, and disturbances in the vertical direction have less effect on it. Compared with the rectangular IDT, the angle range of the excitation and receiving signals of the trapezoidal interdigital transducer is wider, the excitation and receiving signals at different angles can be more suitable, and a certain filtering effect is achieved.
In addition, the interdigital transducer array can be used for being adhered to the surface of a detected member, the performance of the member cannot be influenced, the interdigital transducer array can be used for multi-directionally exciting broadband Lamb wave signals, the frequency range of the interdigital transducer array can be correspondingly adjusted according to the electrode spacing, the interdigital transducer array can be applied to the field of nondestructive detection of metal materials, non-metal materials and composite materials, the interdigital transducer array can be integrated into the materials, the intelligentization is realized, and the development and the wide application of micro-nano sensors, energy collectors and the like can be promoted.
Fig. 8 is a schematic flow chart of a method for manufacturing an interdigital transducer according to an embodiment of the present invention, and as shown in fig. 8, the method for manufacturing an interdigital transducer includes:
step 801: and polarizing the polyvinylidene fluoride material along the thickness direction to obtain the polyvinylidene fluoride substrate.
Step 801 further comprises the steps that the polyvinylidene fluoride substrate is a polyvinylidene fluoride base piezoelectric film, the polyvinylidene fluoride substrate is disc-shaped, and residual materials in the process of preparing the substrate are cleaned before the polyvinylidene fluoride base is solidified.
Step 802: and designing N patterns of trapezoidal interdigital electrode array elements on the bottom surface by taking the polyvinylidene fluoride substrate as the bottom surface.
The step 802 further comprises the steps of taking the polyvinylidene fluoride substrate as a bottom surface, designing N patterns of trapezoidal interdigital electrode array elements on the bottom surface, wherein N is an integer larger than 3, and the plurality of trapezoidal interdigital electrode array elements are uniformly distributed on the surface of the bottom surface along the circumferential direction by taking the circle center of the bottom surface as the center; the anode interdigital electrode of the trapezoidal interdigital electrode array element comprises an anode external connection end and a plurality of mutually spaced anode electrodes, one ends of the anode electrodes are all connected with the anode external connection end, the anode electrodes are coplanar, the cathode interdigital electrode of the trapezoidal interdigital electrode array element comprises a cathode external connection end and a plurality of mutually spaced cathode electrodes, one ends of the cathode electrodes are all connected with the cathode external connection end, and the cathode electrodes are coplanar; a plurality of positive electrodes and a plurality of negative electrodes in each trapezoidal interdigital electrode array element are alternately arranged at intervals; and each two adjacent trapezoidal interdigital electrode array elements share one positive electrode external connection end, and each two adjacent trapezoidal interdigital electrode array elements share one negative electrode external connection end.
Step 803: and depositing the N trapezoidal interdigital electrode array elements on the surface of the polyvinylidene fluoride base by adopting a metal spraying process according to the designed N trapezoidal interdigital electrode array element graphs to obtain the polyvinylidene fluoride base trapezoidal interdigital transducer array.
And step 803, using a JFC-1600 particle sputtering instrument, placing the polyvinylidene fluoride base in a glass cover, using a gold block as a target material, vacuumizing the glass cover, applying high voltage to ionize gold, depositing the gold on the surface of the film, and depositing annular interdigital electrodes, namely a polyvinylidene fluoride trapezoidal interdigital transducer array, on the surface of the flexible polyvinylidene fluoride base.
Step 804: and packaging the polyvinylidene fluoride-based trapezoidal interdigital transducer array by adopting a polymer protective layer.
Before step 804, drying and curing the polyvinylidene fluoride-based trapezoidal interdigital transducer array.
The manufacturing method of the interdigital transducer disclosed by the invention is a method for spraying the trapezoidal interdigital transducer array on the polyvinylidene fluoride substrate through a metal spraying process, the metal spraying process is adopted, a metal spraying wire is melted through high current, high-pressure air blowing is carried out, metal spraying is carried out to form powder, the powder is sprayed on the surface of the polyvinylidene fluoride piezoelectric film, the electrode and the polyvinylidene fluoride film are high in combination degree, the surface roughness is small, batch production is easy to realize, and quality guarantee can be obtained.
In the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the foregoing, the description is not to be taken in a limiting sense.
Claims (6)
1. An interdigital transducer array, comprising: the polyvinylidene fluoride array comprises a polyvinylidene fluoride substrate and N trapezoidal interdigital electrode array elements, wherein N is an integer greater than 3; the polyvinylidene fluoride substrate is disc-shaped, and a plurality of trapezoidal interdigital electrode array elements are uniformly distributed on the surface of the polyvinylidene fluoride substrate along the circumferential direction by taking the circle center of the polyvinylidene fluoride substrate as the center;
the anode interdigital electrode of the trapezoidal interdigital electrode array element comprises an anode external connection end and a plurality of mutually spaced anode electrodes, one ends of the anode electrodes are all connected with the anode external connection end, the anode electrodes are coplanar, the cathode interdigital electrode of the trapezoidal interdigital electrode array element comprises a cathode external connection end and a plurality of mutually spaced cathode electrodes, one ends of the cathode electrodes are all connected with the cathode external connection end, and the cathode electrodes are coplanar; a plurality of positive electrodes and a plurality of negative electrodes in each trapezoidal interdigital electrode array element are alternately arranged at intervals;
each two adjacent trapezoidal interdigital electrode array elements share one positive electrode external connection end, and each two adjacent trapezoidal interdigital electrode array elements share one negative electrode external connection end;
the width of the positive electrode and the width of the negative electrode in the trapezoidal interdigital electrode array element are gradually reduced from the positive external connection end to the negative external connection end.
2. The interdigital transducer array of claim 1, wherein the trapezoidal array of interdigital electrodes is made from gold powder.
3. The interdigital transducer array of claim 1, wherein the polyvinylidene fluoride substrate has a thickness of 0.3mm.
4. A method of fabricating an interdigital transducer, the method comprising:
polarizing a polyvinylidene fluoride material along the thickness direction to obtain a polyvinylidene fluoride substrate, wherein the polyvinylidene fluoride substrate is disc-shaped;
the polyvinylidene fluoride substrate is used as a bottom surface, a graph of N trapezoidal interdigital electrode array elements is designed on the bottom surface, N is an integer larger than 3, and the plurality of trapezoidal interdigital electrode array elements are uniformly distributed on the surface of the bottom surface along the circumferential direction by taking the circle center of the bottom surface as the center; the anode interdigital electrode of the trapezoidal interdigital electrode array element comprises an anode external connection end and a plurality of mutually spaced positive electrodes, one end of each positive electrode is connected with the anode external connection end, the positive electrodes are coplanar, the cathode interdigital electrode of the trapezoidal interdigital electrode array element comprises a cathode external connection end and a plurality of mutually spaced negative electrodes, one end of each negative electrode is connected with the cathode external connection end, and the negative electrodes are coplanar; a plurality of positive electrodes and a plurality of negative electrodes in each trapezoidal interdigital electrode array element are alternately arranged at intervals; each two adjacent trapezoidal interdigital electrode array elements share one positive electrode external connection end, and each two adjacent trapezoidal interdigital electrode array elements share one negative electrode external connection end;
depositing N trapezoidal interdigital electrode array elements on the surface of the polyvinylidene fluoride substrate by adopting a metal spraying process according to the N trapezoidal interdigital electrode array element graphs to obtain a polyvinylidene fluoride-based trapezoidal interdigital transducer array;
packaging the polyvinylidene fluoride-based trapezoidal interdigital transducer array by adopting a polymer protective layer;
the width of the positive electrode and the width of the negative electrode in the trapezoidal interdigital electrode array element are gradually reduced from the positive external connection end to the negative external connection end.
5. The method of claim 4, wherein the array elements of trapezoidal interdigital electrodes are made of gold powder.
6. The method of fabricating an interdigital transducer according to claim 4, wherein the polyvinylidene fluoride substrate has a thickness of 0.3mm.
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