Programmable multi-frequency surface acoustic wave device and regulation and control method and preparation method thereof

Abstract

The invention relates to the technical field of surface acoustic waves, in particular to a programmable multi-frequency surface acoustic wave device and a regulation and control method and a preparation method thereof, the multi-frequency surface acoustic wave device comprises a control circuit and a plurality of chirp interdigital electrode units, and the chirp interdigital electrode units are distributed in an array; the control circuit comprises a signal source and a plurality of control switches, and the control switches are in one-to-one correspondence with the chirp interdigital electrode units; the signal source is used for generating a preset excitation signal with variable frequency; each chirp interdigital electrode unit is connected with the signal source through a control switch, and the control switches are used for controlling the chirp interdigital electrode units to be communicated with the signal source in the forward direction or in the reverse direction and used for generating surface acoustic waves with the phase difference being pi and the response frequency changing according to preset excitation signals; and superposing the surface acoustic waves generated by the plurality of chirp interdigital electrode units in array distribution to form a multi-frequency surface acoustic wave with an expected waveform. According to the invention, fine regulation and control of the multi-frequency surface acoustic waves with complex waveforms can be realized.

Description

Technical Field

[0001] The present invention relates to the field of surface acoustic wave technology, and in particular to a programmable multi-frequency surface acoustic wave device and a control method and a preparation method thereof. Background Art

[0002] Surface acoustic wave (SAW) is an elastic wave that propagates along the surface of a solid. This wave mainly propagates within a thickness range of a few microns to tens of microns on the surface of the solid. Surface acoustic wave technology, with its unique characteristics such as high-frequency operation, low energy loss and high sensitivity, has been widely used in modern science and technology. Surface acoustic wave devices can operate in the high-frequency range of tens of MHz to several GHz, which is suitable for the high-frequency requirements of modern communication systems. They are widely used in filters and resonators in wireless communication equipment to achieve frequency selection and signal filtering while ensuring frequency stability and accuracy. In the field of environmental monitoring, surface acoustic wave sensors are extremely sensitive to surface physical and chemical changes. They can detect trace gases in the air such as carbon dioxide and toxic gases, as well as pollutants and liquid concentration changes in water, and monitor environmental quality and water quality in real time. In the biomedical field, surface acoustic wave technology is used in biosensors to detect indicators in blood, separate and screen blood cells, and manipulate cell movement. In addition, surface acoustic wave devices are also widely used in signal processing. They are used in delay lines, mixers and resonators to achieve signal delay, frequency conversion and resonance functions in radar and sonar systems to optimize signal processing effects. The miniaturization and high integration of surface acoustic wave devices make them easy to integrate with other electronic components and systems, and are suitable for portable and embedded applications. Through continuous research and technological improvements, surface acoustic wave technology has shown great potential in these fields and promoted the development of efficient signal processing and precise detection.

[0003] At present, there are two main ways to control surface acoustic waves: one is to control the excitation source, which can be specifically designed for the electrode structure to control the form of the surface acoustic wave. For example, the electrode is designed to be bent or tilted, which can generate surface acoustic waves in the form of focusing, divergence and tilt; the surface acoustic wave can also be controlled from the frequency, and the finger width of a single electrode is designed to be different. By adjusting the frequency of the excitation signal, the fingers of different widths are vibrated to generate surface acoustic waves of different frequencies. This method of controlling the excitation source requires a simple preparation process for the electrode and low loss of the surface acoustic wave, but its electrode structure is single and cannot produce multi-form waveforms. Another control method is to control the propagation path of the surface acoustic wave. Under the premise of using traditional interdigitated electrodes, it realizes the control of the existing surface acoustic wave velocity, amplitude and phase parameters by preparing micro-nano structures or semiconductor structures in the propagation area of ​​the surface acoustic wave. Its advantages are diverse control methods, and its disadvantages are difficulty in preparation, difficulty in integration, and large loss of the surface acoustic wave.

[0004] The control method of the above-mentioned surface acoustic wave device is that due to the single electrode structure of the traditional surface acoustic wave device, on the same piezoelectric substrate, the characteristic parameters of the surface acoustic wave including frequency, wavelength and phase are also fixed, and it is impossible to generate multi-form surface acoustic waves, thus limiting the ability to control the surface acoustic wave to a certain extent. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a programmable multi-frequency surface acoustic wave device and a control method and a preparation method thereof, which solve the technical problem that the prior art has limited control ability of surface acoustic waves and cannot accurately control multi-frequency surface acoustic waves with complex waveforms.

[0007] (II) Technical solution

[0008] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0009] In a first aspect, an embodiment of the present invention provides a programmable multi-frequency surface acoustic wave device, comprising: a control circuit and a plurality of chirped interdigital electrode units, wherein the chirped interdigital electrode units are distributed in an array;

[0010] The control circuit includes a signal source and a plurality of control switches, wherein the control switches correspond to the chirped interdigital electrode units one by one; the signal source is used to generate a preset excitation signal with a frequency change;

[0011] Each of the chirped interdigital electrode units is connected to the signal source via the control switch, and the control switch is used to control the chirped interdigital electrode unit to be connected to the signal source in a forward direction or a reverse direction, so as to generate a surface acoustic wave with a phase difference of π and a response frequency that changes according to a preset excitation signal;

[0012] When a plurality of array-distributed chirped interdigital electrode units are connected to a signal source in a forward direction or in a reverse direction, the surface acoustic waves generated by each chirped interdigital electrode unit are superimposed to form a multi-frequency surface acoustic wave with an expected waveform.

[0013] Optionally, the signal source includes a signal terminal and a ground terminal; the chirped interdigital electrode unit includes a left electrode and a right electrode;

[0014] The control switch includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal; the first input terminal is communicatively connected to the signal terminal, the second input terminal is communicatively connected to the ground terminal, the first output terminal is communicatively connected to the left electrode, and the second output terminal is communicatively connected to the right electrode;

[0015] When the control switch controls the chirped interdigital electrode unit to be connected to the signal source in a forward direction, the control switch connects the signal end to the left electrode and connects the ground end to the right electrode;

[0016] When the control switch controls the chirped interdigital electrode unit to be connected to the signal source in reverse, the control switch connects the signal terminal to the right electrode and connects the ground terminal to the left electrode.

[0017] Optionally, the chirped interdigital electrode comprises a left electrode and a right electrode, each of the left electrode and the right electrode comprises a plurality of fingers, and the chirped interdigital electrode unit is:

[0018] An interdigital electrode unit in which the values ​​of the finger width and the finger spacing vary linearly or nonlinearly in order from near to far from the surface acoustic wave output end of the chirped interdigital electrode unit.

[0019] Optionally, the chirped interdigital electrode units are perpendicular to the same straight line, and the surface acoustic wave output end of each of the chirped interdigital electrode units faces the same direction;

[0020] The number of chirped interdigital electrode units is not less than 10;

[0021] The number of fingers of the chirped interdigitated electrode unit is not less than 15.

[0022] Optionally, when the programmable surface acoustic wave device is used for particle manipulation, a plurality of the chirped interdigital electrode units are perpendicular to the same straight line and are equidistantly distributed from each other, and the surface acoustic wave output end of each of the chirped interdigital electrode units faces the same direction and is located on the same straight line;

[0023] The number of fingers of each chirped interdigital electrode unit is 25 to 75, the number of chirped interdigital electrode units is 20 to 60, and the distance between two adjacent chirped interdigital electrode units is 5 μm to 15 μm;

[0024] The size parameters of the chirped interdigital electrode unit are:

[0025] The values ​​of the finger widths are an arithmetic progression with a tolerance of 0.5 μm to 5 μm from the surface acoustic wave output end of the chirped interdigitated electrode unit from near to far, and the finger width closest to the surface acoustic wave output end is 50 μm to 150 μm; and,

[0026] From the SAW output end of the chirped interdigitated electrode unit, the finger spacing values ​​are an arithmetic progression with a tolerance of 0.5 μm to 5 μm, and the finger spacing closest to the SAW output end is 50 μm to 150 μm.

[0027] Optionally, the number of fingers of each chirped interdigital electrode unit is 50, the number of chirped interdigital electrode units is 40, and the distance between two adjacent chirped interdigital electrode units is 10 μm;

[0028] The size parameters of the chirped interdigital electrode unit are:

[0029] The values ​​of the finger widths are an arithmetic progression with a tolerance of 1 μm from the surface acoustic wave output end of the chirped interdigitated electrode unit from near to far, and the finger width closest to the surface acoustic wave output end is 100 μm; and,

[0030] From the SAW output end of the chirped interdigitated electrode unit, the values ​​of the finger spacings are an arithmetic progression with a tolerance of 1 μm, and the finger spacing closest to the SAW output end is 100 μm.

[0031] In a second aspect, an embodiment of the present invention provides a control method for a programmable multi-frequency surface acoustic wave device, wherein the multi-frequency surface acoustic wave device is the programmable multi-frequency surface acoustic wave device according to the first aspect, and the control method comprises:

[0032] Control the signal source to output a preset excitation signal of a preset frequency, and control the control switch so that all the chirped interdigital electrode units are connected in a forward direction or in a reverse direction to generate a planar surface acoustic wave with a corresponding response frequency; or

[0033] Control the signal source to output a preset excitation signal with a frequency variation, and control the control switch to enable each of the chirped interdigital electrode units to selectively connect in a forward direction or in a reverse direction to generate a multi-frequency surface acoustic wave with a desired waveform; or

[0034] The signal source and the control switch are controlled to change the waveform of the generated multi-frequency surface acoustic wave in real time by changing the preset excitation signal output by the signal source and the connection state between the chirped interdigital electrode unit and the signal source.

[0035] Optionally, the multi-frequency surface acoustic wave device is the multi-frequency surface acoustic wave device described in the first aspect, and the control method includes:

[0036] The control state of the control switch controlling a chirped interdigital electrode unit to be connected to the signal source in a forward direction is set to 1, and the control state of the control switch controlling a chirped interdigital electrode unit to be connected to the signal source in a reverse direction is set to 0;

[0037] When the surface acoustic wave of the expected waveform is a focused surface acoustic wave, the control states of the control switches corresponding to the chirped interdigital electrode units are, in order of adjacent positions, 11100011110000111111111111100001111000111.

[0038] Optionally, the control method further comprises:

[0039] Controlling the signal source to adjust the focal position and focal depth of the focused surface wave by changing the frequency of a preset excitation signal output by the signal source; or,

[0040] The signal source is controlled to extend the focal depth of the focused surface acoustic wave by performing single-channel multi-frequency signal time domain multiplexing on a preset excitation signal.

[0041] In a third aspect, an embodiment of the present invention provides a method for preparing a programmable multi-frequency surface acoustic wave device, wherein the multi-frequency surface acoustic wave device is the programmable multi-frequency surface acoustic wave device according to the first aspect, and the preparation method comprises:

[0042] S1. Clean a 128° YX-cut, 4-inch lithium niobate wafer, evenly spin-coat it with photoresist, and bake it at 100°C for 3 minutes to use as a substrate;

[0043] S2, using a laser direct writer to expose the electrode pattern of the chirped interdigitated electrode units in a preset array distribution on the substrate, and then developing for 30 seconds;

[0044] S3, sequentially coating a 3nm Cr adhesion layer and a 50nm Au electrode layer on the substrate with the existing electrode pattern;

[0045] S4, soaking the substrate in acetone for 2 hours, and then washing it in an ultrasonic cleaner to remove excess photoresist and metal layer, thereby obtaining array-distributed chirped interdigital electrode units;

[0046] S5, attaching the embossing glue to the left electrode pin and the right electrode pin of the chirped interdigital electrode unit, aligning the wiring with the left electrode pin or the right electrode pin and performing preliminary compaction, and then using a compaction machine to compact;

[0047] S6. Connect the wiring to a control circuit to obtain the programmable surface acoustic wave device.

[0048] (III) Beneficial effects

[0049] The multi-frequency surface acoustic wave device proposed in the present invention comprises a control circuit and a plurality of chirped interdigital electrode units, and the chirped interdigital electrode units are distributed in an array; the control circuit comprises a signal source and a plurality of control switches, and the control switches correspond to the chirped interdigital electrode units one by one; the signal source is used to generate a preset excitation signal with a frequency change; each of the chirped interdigital electrode units is connected to the signal source through the control switch, and the control switch is used to control the chirped interdigital electrode unit to be connected to the signal source in a forward direction or in a reverse direction, so as to generate a surface acoustic wave with a phase difference of π and a response frequency that changes according to a preset excitation signal; when a plurality of array-distributed chirped interdigital electrode units are connected to the signal source in a forward direction or in a reverse direction, the surface acoustic waves generated by each chirped interdigital electrode unit are superimposed to form a multi-frequency surface acoustic wave with an expected waveform. The multi-frequency surface acoustic wave device and its control method provided by the present invention array the traditional interdigital electrode finger width, control each electrode array unit individually, and program the entire array, while combining frequency and phase adjustment. Based on the chirped interdigital electrode units distributed in the above array and the control switches corresponding to each chirped interdigital electrode unit, the control circuit can generate a single surface acoustic wave with a phase change of π by controlling each chirped interdigital electrode unit to be connected in the forward direction or the reverse direction, and then control the phase of the single surface acoustic wave generated by each chirped interdigital electrode unit to control the expected multi-waveform surface acoustic wave, thereby breaking through the limitation that only specific waveforms can be generated under the traditional surface acoustic wave fixed electrode structure, and generating multi-frequency and multi-waveform surface acoustic waves on the chirped interdigital electrode structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A schematic diagram of a chirped interdigital electrode unit array of a programmable multi-frequency surface acoustic wave device provided in an embodiment;

[0051] Figure 2 A schematic diagram of the architecture of a programmable multi-frequency surface acoustic wave device provided in an embodiment;

[0052] Figure 3 Schematic diagram of an array distribution mode of chirped interdigitated electrode units in an embodiment;

[0053] Figure 4 Schematic diagram of another array distribution mode of chirped interdigitated electrode units in an embodiment;

[0054] Figure 5 Detailed schematic diagram of a chirped interdigitated electrode array in an embodiment;

[0055] Figure 6 (a) is a frequency response diagram of a programmable multi-frequency surface acoustic wave device provided in an embodiment;

[0056] Figure 6(b) is the surface acoustic wave measured by Doppler laser vibrometer at 7.24 MHz;

[0057] Figure 6 (c) is the surface acoustic wave measured by Doppler laser vibrometer at 7.76 MHz;

[0058] Figure 6 (d) is the surface acoustic wave measured by Doppler laser vibrometer at 8.73 MHz;

[0059] Figure 7 (a) is the acoustic field intensity distribution of the focused surface acoustic wave measured by Doppler laser vibrometer at 7.24 MHz;

[0060] Figure 7 (b) is the acoustic field intensity distribution of the focused surface acoustic wave measured by Doppler laser vibrometer at 7.76 MHz;

[0061] Figure 7 (c) is the acoustic field intensity distribution of the focused surface acoustic wave measured by Doppler laser vibrometer at 8.73 MHz;

[0062] Figure 7 (d) is a focused surface acoustic wave acoustic field distribution diagram of the embodiment with three frequencies of 7.24 MHz, 7.76 MHz and 8.73 MHz;

[0063] Figure 7 (e) is a single-channel 7.24MHz, 7.76MHz, 8.73MHz triple-frequency multiplexing excitation signal and measurement waveform signal of the embodiment;

[0064] Figure 7 (f) is the focal depth diagram of the y-section of the focused acoustic surface wave generated by excitation signals of different frequencies.

[0065] [Description of Reference Numerals]

[0066] 1. Chirped interdigitated electrode unit; 2. Fingers; 3. Connecting wires; 4. Pins; 5. Metal connecting area. DETAILED DESCRIPTION

[0067] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0068] It should be noted that the multi-frequency surface acoustic wave generated by the multi-frequency surface acoustic wave device provided by the present invention refers to the surface acoustic waves of different frequencies that the chirped interdigital electrode unit responds to preset excitation signals of different frequencies. Specifically, each chirped interdigital electrode unit can simultaneously respond to the excitation signal of a specific frequency for fingers in a specific finger width range and generate surface acoustic waves of a specific frequency superimposed in front of the output end. For the preset excitation signal with a changing frequency, the fingers with different finger widths respond and correspondingly generate multi-frequency surface acoustic waves with changing frequencies.

[0069] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0070] Embodiment 1

[0071] like Figure 1 and 2 As shown, this embodiment provides a programmable multi-frequency surface acoustic wave device, including: a control circuit and a plurality of chirped interdigital electrode units, and the chirped interdigital electrode units are distributed in an array.

[0072] The control circuit includes a signal source and multiple control switches, and the control switches correspond to the chirped interdigital electrode units one by one; the signal source is used to generate a preset excitation signal with a changing frequency; each of the chirped interdigital electrode units is connected to the signal source through the control switch, and the control switch is used to control the chirped interdigital electrode unit to be connected to the signal source in a forward direction or a reverse direction, so as to generate a surface acoustic wave with a phase difference of π and a response frequency that changes according to a preset excitation signal.

[0073] When a plurality of array-distributed chirped interdigital electrode units are connected to a signal source in a forward direction or in a reverse direction, the surface acoustic waves generated by each chirped interdigital electrode unit are superimposed to form a multi-frequency surface acoustic wave with an expected waveform.

[0074] The multi-frequency surface acoustic wave device provided by the present invention is to array the finger width of the traditional chirped interdigital electrode, individually control each electrode array unit, program and control the entire array, and combine frequency and phase adjustment at the same time. Based on the chirped interdigital electrode units distributed in the above array, and the control switches corresponding to each interdigital electrode unit, the control circuit can generate a single surface acoustic wave with a phase change of π by controlling each chirped interdigital electrode unit to connect forward or reverse, and then control the expected multi-waveform surface acoustic wave by individually controlling the phase of the single surface acoustic wave generated by each chirped interdigital electrode unit, thereby breaking through the limitation that only specific waveforms can be generated under the fixed electrode structure of the traditional surface acoustic wave, and generating multi-frequency and multi-waveform surface acoustic waves on the chirped interdigital electrode structure.

[0075] In a specific implementation of this embodiment, the signal source includes a signal terminal and a ground terminal; and the chirped interdigital electrode unit includes a left electrode and a right electrode.

[0076] like Figure 1 and Figure 5 As shown, a plurality of chirped interdigitated electrode units 1 are distributed in an array to form a chirped interdigitated electrode array, each of the chirped interdigitated electrode units 1 comprises a left electrode and a right electrode, the left electrode and the right electrode respectively comprise a plurality of fingers 2 and connecting wires 3 connecting the corresponding fingers, the fingers 2 of the left electrode and the fingers 2 of the right electrode are staggered and inserted into each other, pins 4 are respectively arranged at the ends of the connecting wires 3 of the left electrode and the right electrode to facilitate connection with the control switch, and a gradually expanding metal connecting area 5 can be arranged at the connection from the connecting wire 3 to the pin 4 to ensure the reliability of the connection between the two.

[0077] like Figure 2 As shown, the control switch includes a first input end, a second input end and an output end, the first input end includes a terminal A and a terminal B, the second input end includes a terminal E and a terminal F, the output end includes a terminal C and a terminal D, and the positions of the terminals A, C, and E are correspondingly located on the same straight line, and the positions of the terminals B, D, and F are correspondingly located on the same straight line, and the output end is communicatively connected with the chirped interdigital electrode unit. When the output end is connected with the first input end, the terminal C contacts the terminal A, and the terminal D contacts the terminal B, so that the chirped interdigital electrode unit is connected with the signal source in the forward direction; when the output end is connected with the second input end, the terminal C contacts the terminal E, and the terminal D contacts the terminal F, so that the chirped interdigital electrode unit is connected with the signal source in the reverse direction.

[0078] Specifically, the signal source includes a signal terminal and a ground terminal; the chirped interdigitated electrode unit includes a left electrode and a right electrode; the A terminal of the first input terminal is connected to the signal terminal of the signal source, the B terminal of the first input terminal is connected to the ground terminal of the signal source, the E terminal of the second input terminal is connected to the signal terminal of the signal source, the F terminal of the second input terminal is connected to the ground terminal of the signal source, the C terminal of the output terminal is connected to the left electrode of the chirped interdigitated electrode unit, and the D terminal of the output terminal is connected to the right electrode of the chirped interdigitated electrode unit.

[0079] When the control switch controls the chirped interdigital electrode unit to be connected to the signal source in a forward direction, the control switch connects the signal end to the left electrode and connects the ground end to the right electrode;

[0080] When the control switch controls the chirped interdigital electrode unit to be connected to the signal source in reverse, the control switch connects the signal terminal to the right electrode and connects the ground terminal to the left electrode.

[0081] Specifically, the control switch is a multi-pole multi-throw switch or a relay. The control circuit provided in this embodiment also includes a controller, which is used to encode the connection state of the control switch to control the corresponding chirped interdigital electrode unit to be connected to the signal source in a forward direction or in a reverse direction. The connection state includes forward connection and reverse connection.

[0082] In another specific implementation of this embodiment, the number, size and array distribution of the chirped interdigital electrode units can be further designed according to the specific application scenario.

[0083] For a specific chirped interdigital electrode unit, the chirped interdigital electrode includes a left electrode and a right electrode, each of the left electrode and the right electrode includes a plurality of fingers, and the chirped interdigital electrode unit includes:

[0084] A chirped interdigital electrode unit in which the values ​​of the finger width and the finger spacing vary linearly or nonlinearly in order from the surface acoustic wave output end of the chirped interdigital electrode unit to the farthest point.

[0085] Specifically, for the array distribution of the chirped interdigital electrode units, Figure 1 As shown, a plurality of chirped interdigital electrode units may be perpendicular to the same straight line and equidistantly distributed from each other, and the surface acoustic wave output end of each chirped interdigital electrode unit faces the same direction and is located in the same straight line; or Figure 3 As shown, a plurality of chirped interdigital electrode units can be perpendicular to the same straight line and equidistantly distributed from each other, and the surface acoustic wave output end of each chirped interdigital electrode unit is cross-distributed front and back, so that the output end of the chirped interdigital electrode array as a whole is sawtooth-shaped; it can also be as shown Figure 4As shown, a plurality of chirped interdigital electrode units may be evenly distributed along the same arc, and the surface acoustic wave output end of each of the chirped interdigital electrode units faces the focus of the arc.

[0086] Preferably, the plurality of chirped interdigital electrode units are perpendicular to the same straight line, and the surface acoustic wave output end of each chirped interdigital electrode unit faces the same direction; the number of chirped interdigital electrode units is not less than 10; and the number of fingers of the chirped interdigital electrode unit is not less than 15.

[0087] More preferably, the plurality of chirped interdigital electrode units are perpendicular to the same straight line and are equidistantly distributed from each other, the surface acoustic wave output end of each chirped interdigital electrode unit faces the same direction and is located on the same straight line, and the parameters of the chirped interdigital electrode array are as follows:

[0088] The number of fingers of each chirped interdigital electrode unit is 25 to 75, the number of chirped interdigital electrode units is 20 to 60, and the distance between two adjacent chirped interdigital electrode units is 5 μm to 15 μm;

[0089] The size parameters of the chirped interdigital electrode unit are:

[0090] The values ​​of the finger widths are an arithmetic progression with a tolerance of 0.5 μm to 5 μm from the surface acoustic wave output end of the chirped interdigitated electrode unit from near to far, and the finger width closest to the surface acoustic wave output end is 50 μm to 150 μm; and,

[0091] From the SAW output end of the chirped interdigitated electrode unit, the finger spacing values ​​are an arithmetic progression with a tolerance of 0.5 μm to 5 μm, and the finger spacing closest to the SAW output end is 50 μm to 150 μm.

[0092] It should be noted that Figure 5 As shown, the definitions of various parameters of the above-mentioned chirped interdigitated electrode array are explained as follows: the number of fingers of the chirped interdigitated electrode unit refers to the sum of the number of fingers of the left electrode and the right electrode in a chirped interdigitated electrode unit; the finger width of the chirped interdigitated electrode unit refers to the width of a finger in the direction of the center line of the chirped interdigitated electrode unit; the finger spacing of the chirped interdigitated electrode refers to the distance between two adjacent fingers; the width of the chirped interdigitated electrode unit refers to the distance between the connecting line of the left electrode and the connecting line of the right electrode of the chirped interdigitated electrode unit; the spacing of the chirped interdigitated electrode units refers to the spacing between the right electrode connecting line of the left chirped interdigitated electrode unit and the left electrode connecting line of the right chirped interdigitated electrode unit for two adjacent chirped interdigitated electrode units.

[0093] The parameters of the chirped interdigital electrode array can be further optimized when used in specific scenarios. For example, when the programmable multi-frequency surface acoustic wave device is used for signal filters, nondestructive testing or particle manipulation, the number of fingers of each chirped interdigital electrode unit is 50, the number of chirped interdigital electrode units is 40, and the spacing between two adjacent chirped interdigital electrode units is 10 μm;

[0094] The size parameters of the chirped interdigital electrode unit are:

[0095] The values ​​of the finger widths are an arithmetic progression with a tolerance of 1 μm from the surface acoustic wave output end of the chirped interdigitated electrode unit from near to far, and the finger width closest to the surface acoustic wave output end is 100 μm; and,

[0096] From the SAW output end of the chirped interdigitated electrode unit, the values ​​of the finger spacings are an arithmetic progression with a tolerance of 1 μm, and the finger spacing closest to the SAW output end is 100 μm.

[0097] Embodiment 2

[0098] Based on the programmable multi-frequency surface acoustic wave device provided in the first embodiment, this embodiment specifically describes its control method.

[0099] An embodiment of the present invention provides a control method for a surface acoustic wave device, the control method comprising:

[0100] The signal source is controlled to output a preset excitation signal of a preset frequency, and the control switch is controlled to make all the chirped interdigital electrode units connected in a forward direction or in a reverse direction to generate a planar surface acoustic wave with a corresponding response frequency.

[0101] The signal source is controlled to output a preset excitation signal with a frequency variation, and the control switch is controlled to make each of the chirped interdigital electrode units selectively connected in a forward direction or in a reverse direction to generate a multi-frequency surface acoustic wave with a desired waveform.

[0102] The signal source and the control switch are controlled to change the waveform of the generated multi-frequency surface acoustic wave in real time by changing the preset excitation signal output by the signal source and the connection state between the chirped interdigital electrode unit and the signal source.

[0103] The control state of the control switch controlling a chirped interdigital electrode unit to be connected to the signal source in the forward direction is set to 1, and the control state of the control switch controlling a chirped interdigital electrode unit to be connected to the signal source in the reverse direction is set to 0.

[0104] When the surface acoustic wave of the expected waveform is a focused surface acoustic wave, the control states of the control switches corresponding to the chirped interdigital electrode units are, in order of adjacent positions, 11100011110000111111111111100001111000111.

[0105] For the focused surface acoustic wave, the signal source is controlled to adjust the focal position and focal depth of the focused surface acoustic wave by changing the frequency of the preset excitation signal output by the signal source. The signal source is controlled to extend the focal depth of the focused surface acoustic wave by performing single-channel multi-frequency signal time domain multiplexing on the preset excitation signal.

[0106] Based on the above control method, this embodiment also carried out relevant experimental verification.

[0107] Specifically, the multi-frequency surface acoustic wave device is configured as follows: Figure 1 The multi-frequency surface acoustic wave device shown in the figure has 50 fingers of each chirped interdigitated electrode unit, 40 chirped interdigitated electrode units, and a spacing between two adjacent chirped interdigitated electrode units of 10 μm; the size parameters of the chirped interdigitated electrode units are as follows: from the surface acoustic wave output end of the chirped interdigitated electrode unit, the value of the finger width is an arithmetic progression with a tolerance of 1 μm, and the finger width closest to the surface acoustic wave output end is 100 μm; and, from the surface acoustic wave output end of the chirped interdigitated electrode unit, the value of the finger spacing is an arithmetic progression with a tolerance of 1 μm, and the finger spacing closest to the surface acoustic wave output end is 100 μm.

[0108] The control signal source (signal generator) generates a frequency range of 5MHz to 12MHz and an amplitude of 20V pp The sinusoidal voltage signal is used as the preset excitation signal and input into the chirped interdigital electrode unit through the control switch. The Doppler laser vibrometer is used to take multi-point samples at 1 mm in front of the electrode in the direction of sound wave propagation to obtain the surface acoustic wave amplitude at different frequencies, such as Figure 6 (a) shown. Figure 6In (a), the full width at half maximum is 2.8MHz (6.6MHz to 9.4MHz), which means that the chirped interdigital electrodes in this experiment can respond significantly to signals within this frequency range and can generate multi-frequency surface acoustic waves. The Doppler laser vibrometer has obvious resonance peaks at 7.24MHz, 7.76MHz and 8.73MHz, respectively. In order to obtain a higher signal-to-noise ratio, the surface acoustic waves of these three frequencies (respectively denoted as f1, f2, and f3) are studied next. The chirped interdigital electrode array encoding is set to "1111111111111111111111111111111111111111" or "000000000000000000000000000000000000000000", that is, each chirped interdigital electrode unit has the same phase, which can generate plane surface acoustic waves. By using a Doppler laser vibrometer to scan a 1mm×2mm area in the direction of sound wave propagation, plane acoustic surface waves at f1, f2 and f3 can be obtained. The results are as follows: Figure 6 (b) to (d) Therefore, the multi-frequency surface acoustic wave device provided by the present invention can realize the generation of multi-frequency surface acoustic waves on a single electrode.

[0109] Based on the same surface acoustic wave device and surface acoustic wave measurement method mentioned above, focused surface acoustic waves are achieved through reasonable encoding, and by adjusting the frequency of the input signal, a Doppler laser vibrometer is used to scan an area of ​​1.5cm×2.5cm in the direction of sound wave propagation, and the offset of the focus position of the focused surface acoustic wave and the change of focal depth are obtained by scanning. When the design code is (from left to right) "1110001111000011111111111100001111000111", the chirped interdigitated electrode array can generate focused surface acoustic waves. By changing the frequency of the excitation signal to 7.24MHz, 7.76MHz and 8.73MHz (respectively denoted as f1, f2, f3), the sound field intensity distribution of the corresponding focused surface acoustic wave is obtained by scanning, as shown in FIG. Figure 7 As shown in (a)-(c), with the increase of the excitation signal frequency, the focus of the focused surface acoustic wave also moves toward the +y direction, with a maximum moving distance of 11 mm, and the corresponding focal depths are 20λ, 26λ, and 24λ, respectively. Figure 7 That is to say, after encoding the chirped interdigital electrode array to generate a focused surface acoustic wave, the present embodiment can also control the frequency of the excitation signal to regulate the focused surface acoustic wave generated by the chirped interdigital electrode array, thereby controlling the focal position and focal depth of the focused surface acoustic wave.

[0110] Based on the same surface acoustic wave device and surface acoustic wave measurement method mentioned above, the three frequencies of 7.24MHz, 7.76MHz and 8.73MHz (respectively denoted as f1, f2, f3) are then multiplexed on a single channel. The specific implementation method is to first use MATLAB to generate three corresponding sinusoidal waveforms f1, f2, and f3 respectively, and then select 5 cycles of sinusoidal waveforms for splicing in the time domain and export the wave data. The corresponding excitation signal is generated in the input signal generator through waveform format conversion, and the number of wave cycles is set. In this experiment, each sampling point is set to 10 cycles to record the average value. Use a Doppler laser vibrometer to take multi-point samples 1mm in front of the electrode in the direction of sound wave propagation to obtain the time domain waveform of the multi-frequency multiplexed surface acoustic wave as shown in the figure. Figure 7 As shown in (e), compared with the input waveform, the period is completely consistent. Under the excitation of the multiplexed excitation signal, the focal depth of the focused surface acoustic wave obtained by the acoustic field scanning is significantly extended, as shown in Figure 7 (d) As shown in the figure, the focal depth of the focused SAW is 35λ, which is significantly longer than that of the single-frequency excitation. Figure 7 (f) The multi-frequency surface acoustic wave device provided by the present invention realizes the extension of the focal depth of the focused surface acoustic wave under specific coding through time domain multiplexing of single-channel multi-frequency signals.

[0111] Embodiment 3

[0112] The embodiment of the present invention provides a method for preparing a surface acoustic wave device, which is used to prepare the programmable surface acoustic wave device described in the first embodiment.

[0113] The preparation method comprises steps S1 to S6:

[0114] S1. Clean a 128° YX-cut, 4-inch lithium niobate wafer, evenly spin-coat it with RZJ-304-10 positive photoresist at a speed of 3000 rpm for 30 seconds, and bake it at 100°C for 3 minutes to use as a substrate.

[0115] S2. Using a laser direct writer, the electrode pattern of the chirped interdigitated electrode units with a preset array distribution is exposed on the substrate, followed by development for 30 seconds.

[0116] S3. Use electron beam evaporation technology to sequentially deposit a 3 nm Cr adhesion layer and a 50 nm Au electrode layer on the substrate with the existing electrode pattern.

[0117] S4. Soak the substrate in acetone for 2 hours, and then put it in an ultrasonic cleaner and clean it for 20 minutes using a power of 60W to remove excess photoresist and metal layer to obtain array-distributed chirped interdigitated electrode units.

[0118] S5. Attach the embossed glue to the left electrode pin and the right electrode pin of the chirped interdigitated electrode unit, align the wiring with the left electrode pin or the right electrode pin and perform preliminary compaction, then place the connection between the pin and the wiring in a compaction machine and apply 167MPa and 140°C for compaction.

[0119] S6. Connect the wiring to a control circuit to obtain the programmable surface acoustic wave device.

[0120] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0121] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present invention. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions.

[0122] It should be noted that in the claims, any reference numerals placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In the claims enumerating several means, several of these means may be embodied by the same hardware. The use of the words first, second, third, etc., is for convenience of expression only and does not indicate any order. These words may be understood as part of the component name.

[0123] In addition, it should be noted that, in the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0124] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments after knowing the basic creative concept. Therefore, the claims should be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0125] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention should also include these modifications and variations.

Claims

1. A programmable multi-frequency surface acoustic wave device, characterized in that: include: A control circuit and a plurality of chirped interdigital electrode units, wherein the chirped interdigital electrode units are distributed in an array; The control circuit includes a signal source and a plurality of control switches, wherein the control switches correspond to the chirped interdigital electrode units one by one; the signal source is used to generate a preset excitation signal with a frequency change; Each of the chirped interdigital electrode units is connected to the signal source via the control switch, and the control switch is used to control the chirped interdigital electrode unit to be connected to the signal source in a forward direction or a reverse direction, so as to generate a surface acoustic wave with a phase difference of π and a response frequency that changes according to a preset excitation signal; When a plurality of array-distributed chirped interdigital electrode units are connected to a signal source in a forward direction or in a reverse direction, the surface acoustic waves generated by each chirped interdigital electrode unit are superimposed to form a multi-frequency surface acoustic wave with an expected waveform.

2. The multi-frequency surface acoustic wave device according to claim 1, characterized in that: The signal source includes a signal terminal and a ground terminal; the chirped interdigital electrode unit includes a left electrode and a right electrode; The control switch includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal; the first input terminal is communicatively connected to the signal terminal, the second input terminal is communicatively connected to the ground terminal, the first output terminal is communicatively connected to the left electrode, and the second output terminal is communicatively connected to the right electrode; When the control switch controls the chirped interdigital electrode unit to be connected to the signal source in a forward direction, the control switch connects the signal end to the left electrode and connects the ground end to the right electrode; When the control switch controls the chirped interdigital electrode unit to be connected to the signal source in reverse, the control switch connects the signal terminal to the right electrode and connects the ground terminal to the left electrode.

3. The multi-frequency surface acoustic wave device according to claim 1, characterized in that: The chirped interdigital electrode comprises a left electrode and a right electrode, each of the left electrode and the right electrode comprises a plurality of fingers, and the chirped interdigital electrode unit is: An interdigital electrode unit in which the values ​​of the finger width and the finger spacing vary linearly or nonlinearly in order from near to far from the surface acoustic wave output end of the chirped interdigital electrode unit.

4. The multi-frequency surface acoustic wave device according to claim 3, characterized in that: The chirped interdigital electrode units are perpendicular to the same straight line, and the surface acoustic wave output ends of each of the chirped interdigital electrode units face the same direction; The number of chirped interdigital electrode units is not less than 10; The number of fingers of the chirped interdigitated electrode unit is not less than 15.

5. The multi-frequency surface acoustic wave device according to claim 4, characterized in that: When the programmable surface acoustic wave device is used for particle manipulation, the plurality of chirped interdigital electrode units are perpendicular to the same straight line and are equidistantly distributed from each other, and the surface acoustic wave output end of each chirped interdigital electrode unit faces the same direction and is located on the same straight line; The number of fingers of each chirped interdigital electrode unit is 25 to 75, the number of chirped interdigital electrode units is 20 to 60, and the distance between two adjacent chirped interdigital electrode units is 5 μm to 15 μm; The size parameters of the chirped interdigital electrode unit are: From the surface acoustic wave output end of the chirped interdigital electrode unit, the values ​​of the finger widths are an arithmetic progression with a tolerance of 0.5 μm to 5 μm, and the finger width closest to the surface acoustic wave output end is 50 μm to 150 μm; as well as, From the SAW output end of the chirped interdigitated electrode unit, the finger spacing values ​​are an arithmetic progression with a tolerance of 0.5 μm to 5 μm, and the finger spacing closest to the SAW output end is 50 μm to 150 μm.

6. The multi-frequency surface acoustic wave device according to claim 5, characterized in that: The number of fingers of each chirped interdigital electrode unit is 50, the number of chirped interdigital electrode units is 40, and the distance between two adjacent chirped interdigital electrode units is 10 μm; The size parameters of the chirped interdigital electrode unit are: From the SAW output end of the chirped interdigitated electrode unit, the values ​​of the finger widths are an arithmetic progression with a tolerance of 1 μm, and the finger width closest to the SAW output end is 100 μm; as well as, From the SAW output end of the chirped interdigitated electrode unit, the values ​​of the finger spacings are an arithmetic progression with a tolerance of 1 μm, and the finger spacing closest to the SAW output end is 100 μm.

7. A control method for a programmable multi-frequency surface acoustic wave device, characterized in that: The multi-frequency surface acoustic wave device is a programmable multi-frequency surface acoustic wave device according to any one of claims 1 to 6, and the control method comprises: Control the signal source to output a preset excitation signal of a preset frequency, and control the control switch so that all the chirped interdigital electrode units are connected in a forward direction or in a reverse direction to generate a planar surface acoustic wave with a corresponding response frequency; or Control the signal source to output a preset excitation signal with a frequency variation, and control the control switch to enable each of the chirped interdigital electrode units to selectively connect in a forward direction or in a reverse direction to generate a multi-frequency surface acoustic wave with a desired waveform; or The signal source and the control switch are controlled to change the waveform of the generated multi-frequency surface acoustic wave in real time by changing the preset excitation signal output by the signal source and the connection state between the chirped interdigital electrode unit and the signal source.

8. The control method according to claim 7, characterized in that: The multi-frequency surface acoustic wave device is the multi-frequency surface acoustic wave device according to claim 6, and the control method comprises: The control state of the control switch controlling a chirped interdigital electrode unit to be connected to the signal source in a forward direction is set to 1, and the control state of the control switch controlling a chirped interdigital electrode unit to be connected to the signal source in a reverse direction is set to 0; When the surface acoustic wave of the expected waveform is a focused surface acoustic wave, the control states of the control switches corresponding to the chirped interdigital electrode units are, in order of adjacent positions, 11100011110000111111111111100001111000111.

9. The control method according to claim 8, characterized in that: The control method further comprises: Controlling the signal source to adjust the focal position and focal depth of the focused surface wave by changing the frequency of a preset excitation signal output by the signal source; or, The signal source is controlled to extend the focal depth of the focused surface acoustic wave by performing single-channel multi-frequency signal time domain multiplexing on a preset excitation signal.

10. A method for preparing a programmable multi-frequency surface acoustic wave device, characterized in that: The multi-frequency surface acoustic wave device is a programmable multi-frequency surface acoustic wave device according to any one of claims 1 to 6, and the preparation method comprises: S1. Clean a 128° YX-cut, 4-inch lithium niobate wafer, evenly spin-coat it with photoresist, and bake it at 100°C for 3 minutes to use as a substrate; S2, using a laser direct writer to expose the electrode pattern of the chirped interdigitated electrode units in a preset array distribution on the substrate, and then developing for 30 seconds; S3, sequentially coating a 3nm Cr adhesion layer and a 50nm Au electrode layer on the substrate with the existing electrode pattern; S4, soaking the substrate in acetone for 2 hours, and then washing it in an ultrasonic cleaner to remove excess photoresist and metal layer, thereby obtaining array-distributed chirped interdigital electrode units; S5, attaching the embossing glue to the left electrode pin and the right electrode pin of the chirped interdigital electrode unit, aligning the wiring with the left electrode pin or the right electrode pin and performing preliminary compaction, and then using a compaction machine to compact; S6. Connect the wiring to a control circuit to obtain the programmable surface acoustic wave device.

Images