Broadband sound vibration velocity sensing structure based on random silk screen structure and preparation method thereof

Abstract

The invention discloses a broadband acoustic vibration velocity sensing structure based on a random screen mesh structure and a preparation method thereof, and belongs to the technical field of acoustic measurement. The broadband sound vibration velocity sensitive structure is higher in sound field measurement sensitivity and sound field response fidelity; even if one or more fiber structures are damaged, the device can work reliably; the structure has a micron scale, and meanwhile, the structure also has good acoustic compliance and acoustic impedance, so that good coupling with acoustic vibration of air can be realized, and broadband acoustic vibration velocity measurement is realized; the deformation of the acoustic transducer is mainly influenced by viscous force in a sound field, the acoustic response sensitivity in the range from low frequency to medium-high frequency is consistent, and a single structure has essential sound field directivity; according to the method for preparing the broadband acoustic vibration velocity sensitive structure, the acoustic vibration velocity sensitive structure has the characteristics of large area and small line width at the same time, the overall area can exceed the millimeter magnitude, and the line width scale can reach the micrometer or even nanometer magnitude; the method is suitable for building an optical detection system to realize sound field measurement.

Description

Technical Field

[0001] The invention discloses a broadband acoustic vibration velocity sensing structure based on a random wire mesh structure and a preparation method thereof, belonging to the technical field of acoustic measurement. Background Art

[0002] Acoustic sensors are widely used in speech signals, industrial detection, military and defense industries. With the continuous expansion of acoustic application scenarios, the performance requirements for acoustic sensors in occasions such as speech enhancement, sound source localization, scene recording, and sound measurement in complex environments are gradually increasing. These occasions usually require filtering environmental noise and enhancing the acoustic characteristics of the target to be measured.

[0003] The diaphragm structure is the core component of the acoustic sensor, but the driving force of the diaphragm structure currently used when detecting acoustic signals mainly comes from the sound pressure signal to be measured, and it is usually an omnidirectional acoustic sensor.

[0004] Currently common directional acoustic sensors mainly include:

[0005] First, use the array structure to calculate the spatial sound field gradient information. This solution requires placing sensors at two different locations in space and measuring the sound field gradient information by taking the difference. The lower the frequency of the sound signal to be measured, the larger the array size; and its sensitivity is proportional to the signal frequency, resulting in low measurement sensitivity of the sound sensor in the low frequency band;

[0006] Second, use isoscillation-type accelerometers to measure acceleration information in the sound field, and obtain vibration velocity information through integration. However, this solution requires the accelerometer to be packaged in zero buoyancy, which is generally only used in underwater acoustic environments and is difficult to implement in air environments.

[0007] Third, directly use the vibration velocity sensor to measure the vibration velocity information in the sound field. The patent "An air sound particle vibration velocity sensor and its manufacturing method" reports a method for detecting the sound vibration velocity based on measuring the change of the resistance of adjacent thin wires with the sound field; a similar structure is reported in the paper "A thermal convection MEMS two-dimensional particle vibration velocity sensor". However, this vibration velocity sensor requires heating of the sound sensitive device, which increases the power consumption of the device and limits its scope of use. Compared with the sound vibration velocity sensor based on thermal field detection, the use of nanofibers for sound vibration velocity measurement has the advantage of low power consumption. The patent "Fiber Microphone" proposes a sound vibration velocity sensor based on nano conductive fibers, which places a one-dimensional conductive fiber in a magnetic field, and controls the diameter and length of the conductive fiber so that its driving force is determined by the viscosity of the fluid. However, one-dimensional conductive fibers are easily damaged under the action of external forces, resulting in device failure. And the one-dimensional nanofiber structure is not suitable for the integration of optical detection means. Summary of the invention

[0008] In view of the above problems, the present invention designs a broadband acoustic velocity sensing structure based on a random wire mesh structure and a preparation method thereof, wherein the broadband acoustic velocity sensitive structure based on the random wire mesh structure of the present invention is produced by a crack process, which can effectively release the internal stress generated by the wire mesh during the preparation process, and the acoustic field measurement sensitivity and acoustic field response fidelity are higher; even if one or more fiber structures are damaged, the device can still work reliably, and has the advantages of high mechanical stability and low failure rate, and is suitable for the integration of optical detection means; the broadband acoustic velocity sensitive structure has a micron scale, and at the same time, the structure has good acoustic compliance and acoustic impedance, so it can realize acoustic vibration with the air. Good coupling, thereby realizing wide-band acoustic velocity measurement; its deformation is mainly affected by the viscosity in the sound field, and the acoustic response sensitivity is consistent in the range from low frequency (<0.1Hz) to medium and high frequency (>5kHz), and a single structure has essential acoustic field directivity; the method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure of the present invention not only has simple process steps, high reliability and low processing cost, but also enables the acoustic velocity sensitive structure to take into account the characteristics of large area and small line width at the same time, the overall area can exceed the millimeter level, and the line width scale can reach the micrometer or even nanometer level; the conversion mechanism is rich, and it is particularly suitable for building an optical detection system to realize acoustic field measurement.

[0009] The object of the present invention is achieved in that:

[0010] The method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure comprises the following steps:

[0011] Step a, preparing the grinding liquid;

[0012] Step b, substrate cleaning;

[0013] Step c, applying masking liquid;

[0014] Step d, drying the masking liquid;

[0015] Step e, coating;

[0016] Step f, removing the mask;

[0017] Step g: Random spider web release.

[0018] In the above-mentioned method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure, in step a, the masking liquid is an aqueous acrylic emulsion diluted with a diluent, and step a specifically comprises the following steps:

[0019] Step a1, mixing the aqueous acrylic emulsion and the diluent according to a set volume ratio;

[0020] Step a2, sequentially using magnetic stirring and ultrasonic oscillation to mix the mixed solution uniformly;

[0021] Step a3, filtering the mixed solution obtained in step a2 2 to 3 times with medium-speed filter paper;

[0022] At the end of step a4, the prepared masking liquid is sealed and stored, and can be used after being allowed to stand.

[0023] The above-mentioned method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure, step b specifically comprises the following steps:

[0024] Step b1, ultrasonically cleaning the surface of the substrate with an organic solvent, wherein the organic solvent includes acetone, ethanol or isopropanol;

[0025] Step b2, re-wash with deionized water until the surface is completely clean;

[0026] Step b3: Blow dry the substrate sample with nitrogen and set it aside.

[0027] The above-mentioned method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure, step c specifically comprises the following steps:

[0028] Step c1, using a spin coating method to evenly coat the mask liquid on the surface of the substrate to obtain a mask liquid film;

[0029] Step c2, placing the substrate on a flat metal vacuum chuck to rotate with the tray;

[0030] Step c3: Control the thickness of the mask liquid film by adjusting the maximum rotation speed of the spin coating.

[0031] In the above-mentioned preparation method of a broadband acoustic velocity sensitive structure based on a random wire mesh structure, in step d, the uniformly coated mask liquid film is very thin, and the solvent evaporates at room temperature. During the solvent evaporation process, the colloidal particles continue to gather and shrink, causing internal stress in the film; when the internal stress continues to increase with the evaporation of the solvent and exceeds the critical stress, the film will crack, eventually forming a well-connected crack network, i.e., a crack template.

[0032] The above-mentioned method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure, in step e, depositing the wire mesh material in the random cracks obtained in step d, comprises one of the following methods:

[0033] Method 1: Depositing a metal film layer by electron beam evaporation; the metal film layer comprises gold, silver, copper or aluminum;

[0034] Method 2: depositing a metal film layer by magnetron sputtering; the metal film layer comprises gold, silver, copper or aluminum;

[0035] Method three: coating of an organic film layer or an inorganic film layer is achieved by a scraping process, wherein the organic film layer is PMMA, PI, PU, ​​PC or PET, and the inorganic film layer is graphene oxide or carbon nanotubes.

[0036] In the above-mentioned method for preparing a broadband acoustic vibration velocity sensitive structure based on a random wire mesh structure, in step f, the zinc sulfide substrate is ultrasonically cleaned using N-methylpyrrolidone, ethanol and deionized water respectively, and finally the broadband acoustic vibration velocity sensitive structure based on a random wire mesh structure is blown dry with nitrogen and inspected.

[0037] In the above-mentioned method for preparing the broadband acoustic vibration velocity sensitive structure based on the random wire mesh structure, in step g, a deep etching process substrate structure is adopted to realize the suspension of the broadband acoustic vibration velocity sensitive structure based on the random wire mesh structure.

[0038] The broadband sound velocity sensitive structure based on random wire mesh structure is a structure obtained by the preparation method of the broadband sound velocity sensitive structure based on random wire mesh structure.

[0039] In the above-mentioned broadband acoustic velocity sensitive structure based on a random wire mesh structure, the cross-sectional width of each wire is in the nanometer range.

[0040] The broadband acoustic velocity sensitive structure based on random wire mesh structure and the preparation method thereof have the following beneficial effects:

[0041] First, the broadband acoustic velocity sensitive structure based on the random wire mesh structure of the present invention is produced by a crack process, which can effectively release the internal stress generated by the wire mesh during the preparation process, and the acoustic field measurement sensitivity and acoustic field response fidelity are higher;

[0042] Second, the broadband acoustic velocity sensitive structure of the present invention based on the random wire mesh structure can work reliably even if one or more fiber structures are damaged. It has the advantages of high mechanical stability and low failure rate, and is suitable for the integration of optical detection means.

[0043] Third, the broadband acoustic velocity sensitive structure based on the random wire mesh structure of the present invention has a micrometer or even nanometer scale, and at the same time, the structure has good acoustic compliance and acoustic impedance, so it can achieve good coupling with the acoustic vibration of the air, thereby realizing broadband acoustic velocity measurement;

[0044] Fourth, the deformation of the broadband acoustic velocity sensitive structure based on the random wire mesh structure of the present invention is mainly affected by the viscosity in the sound field, and the acoustic response sensitivity is consistent in the range from low frequency (<0.1Hz) to medium and high frequency (>5kHz), and the single structure has the essential sound field directivity;

[0045] Fifth, the method for preparing the broadband acoustic velocity sensitive structure based on the random wire mesh structure of the present invention not only has simple process steps, high reliability and low processing cost, but also enables the acoustic velocity sensitive structure to have both large area and small line width. The overall area can exceed the millimeter level, and the line width can reach the micrometer or even nanometer level.

[0046] Sixth, the broadband acoustic velocity sensitive structure based on the random wire mesh structure of the present invention has rich conversion mechanisms and is particularly suitable for building an optical detection system to achieve sound field measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a process flow chart of a method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure.

[0048] Figure 2 This is a physical picture of the broadband acoustic velocity sensitive structure based on a random wire mesh structure.

[0049] Figure 3 The frequency response simulation results of PMMA cilia with different diameters.

[0050] Figure 4 This is the frequency response simulation result of the silk screen diaphragm. DETAILED DESCRIPTION

[0051] The specific implementation modes of the present invention will be further described in detail below with reference to the accompanying drawings.

[0052] Method 1

[0053] The following is a specific implementation method of the method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure of the present invention.

[0054] The process flow chart of the preparation method of the broadband acoustic velocity sensitive structure based on the random wire mesh structure in this specific implementation manner is as follows: Figure 1 As shown, the following steps are included:

[0055] Step a, preparing the grinding liquid;

[0056] The masking liquid is an aqueous acrylic emulsion diluted with a diluent, and step a specifically comprises the following steps:

[0057] Step a1, mixing the aqueous acrylic emulsion and the diluent according to a set volume ratio;

[0058] Step a2, sequentially using magnetic stirring and ultrasonic oscillation to mix the mixed solution uniformly;

[0059] Step a3, filtering the mixed solution obtained in step a2 2 to 3 times with medium-speed filter paper;

[0060] At the end of step a4, the prepared masking liquid is sealed and stored, and can be used after being allowed to stand.

[0061] Step b, substrate cleaning;

[0062] The specific steps include:

[0063] Step b1, ultrasonically cleaning the surface of the substrate with an organic solvent, wherein the organic solvent includes acetone, ethanol or isopropanol;

[0064] Step b2, re-wash with deionized water until the surface is completely clean;

[0065] Step b3: Blow dry the substrate sample with nitrogen and set it aside.

[0066] Step c, applying masking liquid;

[0067] The specific steps include:

[0068] Step c1, using a spin coating method to evenly coat the mask liquid on the surface of the substrate to obtain a mask liquid film;

[0069] Step c2, placing the substrate on a flat metal vacuum chuck to rotate with the tray;

[0070] Step c3: Control the thickness of the mask liquid film by adjusting the maximum rotation speed of the spin coating.

[0071] Step d, drying the masking liquid;

[0072] The uniformly coated mask liquid film is very thin, and the solvent evaporates at room temperature. During the solvent evaporation process, the colloidal particles continue to gather and shrink, causing internal stress in the film. When the internal stress continues to increase with the evaporation of the solvent and exceeds the critical stress, the film will crack, eventually forming a well-connected crack network, namely the crack template.

[0073] Step e, coating;

[0074] Depositing the screen material in the random cracks obtained in step d comprises one of the following methods:

[0075] Method 1: Deposition of a metal film layer using electron beam evaporation, wherein the metal film layer includes gold, silver, copper, aluminum, etc.;

[0076] Method 2: using magnetron sputtering to deposit a metal film layer, wherein the metal film layer includes gold, silver, copper, aluminum, etc.;

[0077] Method three: coating of an organic film layer or an inorganic film layer is achieved by a scraping process, wherein the organic film layer is PMMA, PI, PU, ​​PC, PET, etc., and the inorganic film layer is graphene oxide, carbon nanotubes, etc.

[0078] Step f, removing the mask;

[0079] The zinc sulfide substrate was ultrasonically cleaned using N-methylpyrrolidone, ethanol and deionized water respectively, and finally dried with nitrogen and inspected for the broadband acoustic velocity sensitive structure based on the random wire mesh structure.

[0080] Step g: Random spider web release

[0081] The substrate structure is processed by deep etching process to realize the suspension of broadband acoustic velocity sensitive structure based on random wire mesh structure.

[0082] Method 2

[0083] The following is a specific implementation of the broadband acoustic velocity sensitive structure based on a random wire mesh structure of the present invention.

[0084] The broadband acoustic velocity sensitive structure based on a random wire mesh structure in this specific implementation is a structure obtained by the preparation method of the broadband acoustic velocity sensitive structure based on a random wire mesh structure described in the specific implementation method 1. The actual picture is as shown in FIG. Figure 2 As shown, it can be seen that the cross-sectional width of each wire is in the micrometer range, and can reach the nanometer range under more stringent preparation process conditions.

[0085] Method 3

[0086] The following is a specific implementation method of the present invention for characteristic analysis of a broadband acoustic velocity sensitive structure based on a random wire mesh structure.

[0087] A simplified analysis is performed on the broadband acoustic velocity sensitive structure based on a random wire mesh structure, which is decomposed into a series of cilia. First, the force equation of the cilia in the flow field is established. Assuming that the radius of the cilia is r and the length is L, it is subject to the effects of Euler-Bernoulli bending, axial tension, and fluid forces of the surrounding medium. The force equation is expressed as follows:

[0088]

[0089] When r is relatively small, the main force acting on the ciliary motion is proportional to v(t), that is, the relative motion of the ciliary mass with the surrounding medium. So we get:

[0090]

[0091] The above equation shows that when the cilia are thin enough, they will flow with the fluid. Therefore, the movement of cilia can well represent the movement of the medium around them.

[0092] The one-dimensional ciliary motion equation is used for simulation analysis to obtain the transmission efficiency of ciliary structures with different diameters. The results are as follows: Figure 3As shown, Figure a is 0.5 μm and Figure b is 1 μm; the results show that when the diameter of the cilia is small enough, high-fidelity extraction of the vibration of the surrounding fluid medium can be achieved, thereby achieving high-sensitivity perception of acoustic signals, especially low-frequency acoustic signals.

[0093] PMMA was selected as the mesh material, the overall diameter of the model was 10 mm, and the line width of the cilia was 2 μm. The mesh model was simulated at a frequency of 1 Hz to 10,000 Hz, and the frequency response of the mesh was analyzed when a plane acoustic wave with an intensity of 1 Pa was applied to the mesh. Figure 4 As shown. Figure 4 It can be found that the speed transfer ratio of the silk screen in a wider frequency range (especially low frequency) is 1, that is, Vsilk / Vair≈1, which means that low-frequency sound information can be obtained with high fidelity.

Claims

1. A method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure, characterized in that: The following steps are involved: Step a, preparing the grinding liquid; Step b, substrate cleaning; Step c, applying masking liquid; Step d, drying the masking liquid; Step e, coating; Step f, removing the mask; Step g: Random spider web release.

2. The method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure according to claim 1, characterized in that: In step a, the masking liquid is an aqueous acrylic emulsion diluted with a diluent, and step a specifically comprises the following steps: Step a1, mixing the aqueous acrylic emulsion and the diluent according to a set volume ratio; Step a2, sequentially using magnetic stirring and ultrasonic oscillation to mix the mixed solution uniformly; Step a3, filtering the mixed solution obtained in step a2 2 to 3 times with medium-speed filter paper; At the end of step a4, the prepared masking liquid is sealed and stored, and can be used after being allowed to stand.

3. The method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure according to claim 1, characterized in that: Step b specifically comprises the following steps: Step b1, ultrasonically cleaning the surface of the substrate with an organic solvent, wherein the organic solvent includes acetone, ethanol or isopropanol; Step b2, re-wash with deionized water until the surface is completely clean; Step b3: Blow dry the substrate sample with nitrogen and set it aside.

4. The method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure according to claim 1, characterized in that: Step c specifically includes the following steps: Step c1, using a spin coating method to evenly coat the mask liquid on the surface of the substrate to obtain a mask liquid film; Step c2, placing the substrate on a flat metal vacuum chuck to rotate with the tray; Step c3: Control the thickness of the mask liquid film by adjusting the maximum rotation speed of the spin coating.

5. The method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure according to claim 1, characterized in that: In step d, the uniformly coated mask liquid film is very thin, and the solvent evaporates at room temperature. During the solvent evaporation process, the colloidal particles continue to gather and shrink, causing internal stress in the film; when the internal stress continues to increase with the evaporation of the solvent and exceeds the critical stress, the film will crack, eventually forming a well-connected crack network, namely the crack template.

6. The method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure according to claim 1, characterized in that: In step e, the mesh material is deposited in the random cracks obtained in step d, comprising one of the following methods: Method 1: Depositing a metal film layer by electron beam evaporation; the metal film layer comprises gold, silver, copper or aluminum; Method 2: Depositing a metal film layer by magnetron sputtering; the metal film layer comprises gold, silver, copper or aluminum; Method three: coating of an organic film layer or an inorganic film layer is achieved by a scraping process, wherein the organic film layer is PMMA, PI, PU, ​​PC or PET, and the inorganic film layer is graphene oxide or carbon nanotubes.

7. The method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure according to claim 1, characterized in that: In step f, the zinc sulfide substrate is ultrasonically cleaned using N-methylpyrrolidone, ethanol, and deionized water, respectively, and finally dried with nitrogen and inspected for a broadband acoustic velocity sensitive structure based on a random wire mesh structure.

8. The method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure according to claim 1, characterized in that: In step g, a substrate structure is deep-etched to achieve suspension of a broadband acoustic velocity sensitive structure based on a random wire mesh structure.

9. A broadband acoustic velocity sensitive structure based on a random wire mesh structure, characterized in that: The structure is obtained by the method for preparing a broadband acoustic velocity sensitive structure based on a random wire mesh structure as described in claim 1.

10. The broadband acoustic velocity sensitive structure based on a random wire mesh structure according to claim 9, characterized in that: The cross-sectional width of each wire is in the nanometer range.

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