Acoustic sensor and preparation method thereof

Abstract

The invention relates to the field of sensors, and discloses an acoustic sensor and a preparation method thereof. The acoustic sensor comprises an upper support body, an acoustic sensing layer and a lower support body; the acoustic sensing layer comprises a first electrode layer, a flexoelectric material layer and a second electrode layer which are stacked in sequence; the flexoelectric material layer contains a two-dimensional layered material and an ion regulator; the two-dimensional layered material is selected from at least one of graphene oxide, boron nitride, vermiculite, molybdenum disulfide, tungsten diselenide, tungsten disulfide, black phosphorus, Mxene, molybdenum ditelluride and tungsten trioxide; the ion regulator is selected from one or more than two of polystyrolsulfon acid, polyethylene glycol, poly (diallyldimethylammonium chloride), carboxyl ethylene copolymer, polyethylene sulfonic acid, polymethylacrylic acid, polyethylene phosphoric acid, polyvinylamine, sodium alginate, silk fibroin and carboxylated nanofiber. The acoustic sensor operates by using the flexoelectric effect, and has higher sensitivity and high Young modulus.

Description

Technical Field

[0001] The present invention relates to the field of sensors, and particularly to an acoustic sensor and a preparation method thereof. Background Art

[0002] With the advent of the Internet of Things era, wireless and portable electronic products are booming. They are characterized by a large number of sensor devices, low power consumption of a single device, wide distribution locations, etc., which pose new demands on the current energy supply methods. Collecting low-quality environmental mechanical energy, such as human motion energy, vibration energy, wind energy, etc., and converting it into electrical energy can well meet the current energy demands. The current mechanical-electrical conversion mechanisms mainly include piezoelectricity, moisture power generation, concentration difference power generation, triboelectric nanogenerators, and flexoelectricity, etc. At the same time, in order to improve the wearing comfort, higher flexibility requirements are put forward for sensors. Currently, common acoustic sensors mainly sense based on the piezoelectric effect. However, most piezoelectric materials, such as piezoelectric ceramics and piezoelectric crystals, do not have flexibility themselves, which reduces the wearing comfort of the prepared acoustic sensors. Therefore, currently, flexible polymer piezoelectric polymers are more used for sound sensing to improve the wearing comfort of piezoelectric acoustic sensors. However, the current output currents of the piezoelectric acoustic sensors prepared using flexible polymer piezoelectric polymers are very low, seriously affecting the sound accuracy and sensitivity of the acoustic sensors. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problems existing in the prior art, such as insufficient sensitivity and low electrical output of piezoelectric acoustic sensors, and to provide an acoustic sensor and a preparation method thereof. The acoustic sensor operates using the flexoelectric effect, can timely convert sound signals into electrical signals for output, and has higher sensitivity and a high Young's modulus.

[0004] To achieve the above purpose, on the one hand, the present invention provides an acoustic sensor, which includes an upper support body, an acoustic sensing layer, and a lower support body;

[0005] Wherein, the upper support body and the lower support body are correspondingly provided with hollow parts, and the acoustic sensing layer covers the hollow parts and is located between the upper support body and the lower support body;

[0006] The acoustic sensing layer includes a first electrode layer, a flexoelectric material layer, and a second electrode layer that are sequentially stacked;

[0007] The flexoelectric material layer contains two-dimensional layered materials and ionic regulators;

[0008] Among them, the two-dimensional layered material is selected from one or more of graphene oxide, boron nitride, vermiculite, molybdenum disulfide, tungsten diselenide, tungsten disulfide, black phosphorus, Mxene, molybdenum ditelluride, and tungsten trioxide, and the ionic regulator is selected from one or more of polystyrene sulfonic acid, polyethylene glycol, poly(diallyldimethylammonium chloride), carboxyvinyl copolymer, polyvinyl sulfonic acid, polymethacrylic acid, polyvinyl phosphoric acid, polyvinylamine, sodium alginate, silk fibroin, and carboxylated nanofibers.

[0009] The weight ratio of the two-dimensional layered material to the ionic regulator is 1:0.02 - 0.08.

[0010] The thickness of the flexoelectric material layer is 1 - 6 μm.

[0011] Preferably, the two-dimensional layered material is selected from one or more of graphene oxide, boron nitride, vermiculite, and molybdenum disulfide, and the ionic regulator is selected from one or more of polystyrene sulfonic acid, polyethylene glycol, poly(diallyldimethylammonium chloride), and carboxyvinyl copolymer.

[0012] Preferably, the average size of the two-dimensional layered material is ≥500 nm, preferably 500 - 800 nm.

[0013] Preferably, the flexoelectric material layer contains graphene oxide and polystyrene sulfonic acid;

[0014] Preferably, in the flexoelectric material layer, the weight ratio of the graphene oxide to the polystyrene sulfonic acid is 1:0.03 - 0.05.

[0015] Preferably, in the flexoelectric material layer, the content of the ionic regulator is 2 - 8 wt%.

[0016] Preferably, the first electrode layer is selected from one of a gold electrode, a silver electrode, a copper electrode, an aluminum electrode, a silver nanowire electrode, a carbon fiber electrode, and a carbon nanotube electrode;

[0017] Preferably, the second electrode layer is selected from one of a gold electrode, a silver electrode, a copper electrode, an aluminum electrode, a silver nanowire electrode, a carbon fiber electrode, and a carbon nanotube electrode.

[0018] Preferably, the materials of the upper support and the lower support are polymethyl methacrylate.

[0019] The second aspect of the present invention provides a method for preparing the acoustic sensor as described above, and the method includes:

[0020] (1) Mix a dispersion liquid containing a two-dimensional layered material with the ionic regulator, and then prepare the obtained mixed liquid into a film to obtain a flexoelectric material layer;

[0021] (2) Form a first electrode layer and a second electrode layer on the upper surface and the lower surface of the flexoelectric material layer respectively to obtain an acoustic sensing layer;

[0022] (3) Stack and fix the upper support body, the acoustic sensing layer, and the lower support body in sequence from top to bottom;

[0023] In the dispersion liquid containing the two-dimensional layered material, the concentration of the two-dimensional layered material is 0.5 - 4 mg / mL.

[0024] Preferably, the method further includes: regulating the flexoelectric effect of the two-dimensional layered material by adjusting the dosage of the ion regulator.

[0025] The acoustic sensor of the present invention is different from the currently common piezoelectric acoustic sensor that uses the piezoelectric effect for electromechanical conversion. Instead, it uses the flexoelectric effect of the flexoelectric material employed to achieve the conversion between sound and electrical signals, and uses the flexoelectric effect to detect high-frequency sound signals. The acoustic sensor of the present invention can not only meet the flexible requirements, but also has a higher current output. In addition, the two-dimensional layered material used in the acoustics of the present invention has a very high Young's modulus while being able to withstand a very high bending deformation, and has a very high flexoelectric coefficient and high flexibility. At the same time, the ion regulator added to the flexoelectric material layer can directly regulate the flexoelectric effect in the two-dimensional layered material, which can well improve the generated flexoelectric electrical output, thereby further improving the accuracy of the sound of the acoustic sensor. The acoustic sensor based on the flexoelectric effect of the flexoelectric material layer contained in the present invention has a higher recognition accuracy for human voices, a smaller Euclidean distance, has more excellent performance, and higher practicality. Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of the acoustic sensor;

[0027] Figure 2 is a schematic structural diagram of the upper support body and the lower support body;

[0028] Figure 3 is a schematic diagram of the diameter of the two-dimensional layered material.

[0029] Description of the Reference Numerals

[0030] 100 Upper support body; 300 Lower support body;

[0031] 400 Hollow part; 500 Connection component;

[0032] 201 First electrode layer; 202 Flexoelectric material layer;

[0033] 203 The second electrode layer. Detailed implementation manners

[0034] The following will describe in detail the specific implementation manners of the present invention with reference to the accompanying drawings. It should be understood that the specific implementation manners described herein are only for explaining and illustrating the present invention, and are not used to limit the present invention.

[0035] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0036] In the present invention, the structural schematic diagram of the acoustic sensor is as Figure 1 shown. The acoustic sensor includes an upper support body 100, an acoustic sensing layer, and a lower support body 300. The upper support body 100 and the lower support body 300 are used to fix the acoustic sensing layer and maintain the flatness of the acoustic sensing layer so that it can better respond to sound. Specifically, the upper support body 100 and the lower support body 300 are correspondingly provided with a hollowed-out portion 400, and the hollowed-out portion 400 is used for the acoustic sensing layer to perceive external sounds.

[0037] In the present invention, the materials of the upper support body 100 and the lower support body 300 are polymethyl methacrylate.

[0038] In the present invention, the shapes of the upper support body 100 and the lower support body 300 are not limited. For example, they can be circular rings. In some preferred implementation methods, the shape of the upper support body 100 is the same as that of the lower support body 300, and its structural schematic diagram is as Figure 2 shown, both are circular rings, and the outer diameters of the upper support body 100 and the lower support body 300 are the same.

[0039] In a specific implementation manner, the upper support body 100 and the lower support body 300 are correspondingly provided with a connection component 500, and the upper support body 100 and the lower support body 300 fix the acoustic sensing layer through the connection component 500. Specifically, the connection component 500 can be a bolt or a buckle.

[0040] In a specific embodiment, the acoustic sensing layer covers the hollow portion 400 and is disposed between the upper support 100 and the lower support 300, and is connected to both the upper support 100 and the lower support 300 through the connecting assembly 500. The portion of the acoustic sensing layer that covers the hollow portion 400 is used to sense external sounds, and further converts the sound signals into electrical signals through the flexoelectric effect to realize the electromechanical conversion process.

[0041] In the present invention, the acoustic sensing layer includes a first electrode layer 201, a flexoelectric material layer 202, and a second electrode layer 203 that are sequentially stacked. Among them, the first electrode layer 201 and the second electrode layer 203 are used for conducting electricity and output the electrical signals of the middle flexoelectric material layer. Specifically, the specific materials of the first electrode layer 201 and the second electrode layer 203 are not limited, as long as they can still be tightly combined with the flexoelectric material layer 202 and are not easily detached when the flexoelectric material layer 202 is bent. Preferably, the first electrode layer 201 and the second electrode layer 203 are each independently selected from one of a gold electrode, a silver electrode, and a carbon nanotube electrode.

[0042] The flexoelectric effect refers to an electromechanical conversion method in which non-uniform deformation causes polarization. Most of the acoustic sensors prepared in the prior art use the piezoelectric effect of materials to realize the conversion and output of sound and electrical signals, and there is no acoustic sensor that uses the flexoelectric effect of materials for electromechanical conversion. The acoustic sensor described in the present invention operates using the flexoelectric effect possessed by the flexoelectric material layer in the acoustic sensing layer. The acoustic sensor using the flexoelectric effect for electromechanical conversion can not only meet the flexible requirements, but also has a higher current output, and can well solve the problems such as insufficient sensitivity and sound accuracy of the current flexible piezoelectric acoustic sensors. Moreover, compared with the piezoelectric acoustic sensor, the acoustic sensor described in the present invention has a simpler structure, a smaller volume, and is more comfortable to wear.

[0043] In a further preferred embodiment, the first electrode layer 201 is a gold electrode and the second electrode layer 203 is a gold electrode.

[0044] In the present invention, the flexoelectric material layer 202 is used to convert the sound signals received from the outside into electrical signals, and the flexoelectric material layer 202 contains a two-dimensional layered material and an ion regulator.

[0045] Currently, existing flexoelectric materials are either too brittle to withstand large bending deformations or have a very small flexoelectric coefficient. And in flexible flexoelectric materials, the migration rate of ions is very slow and cannot respond in a timely manner to sound frequencies in the thousands of hertz range. In the acoustic sensor described in the present invention, by adding an ion regulator to the flexoelectric material layer 202 or by controlling the amount of the added ion regulator, the flexoionic effect in the two-dimensional layered material is regulated, increasing the output of the flexoionic effect in the two-dimensional layered material, converting the sound signal into an electrical signal, and making the sound accuracy and sensitivity of the acoustic sensor higher and the performance more excellent.

[0046] Specifically, in the acoustic sensor, when a bending stress is applied to the flexoelectric material layer 202, a pressure gradient is formed along the thickness direction inside the flexoelectric material layer 202, causing the ions and water molecules inside the flexoelectric material layer 202 to undergo convection along the direction of the stress gradient, generating ion polarization, and thus generating electrical energy. The conversion between the sound signal and the electrical signal is achieved through the flexoelectric effect possessed by the flexoelectric material layer 202. The acoustic sensor described in the present invention is different from common piezoelectric acoustic sensors in the prior art, which achieve the conversion between the sound signal and the electrical signal through the piezoelectric effect. The acoustic sensor described in the present invention adopts the flexoelectric effect possessed by the flexoelectric material layer 202, and thus can achieve the monitoring of high-frequency sound signals, has a higher electrical output and a higher accuracy for sound, and has a smaller Euclidean distance.

[0047] In the present invention, the two-dimensional layered material has a high Young's modulus, can withstand high bending deformations, and also has a high flexoionic coefficient, so that the acoustic sensor can have more excellent performance. The two-dimensional layered material is selected from one or more of graphene oxide, boron nitride, vermiculite, molybdenum disulfide, tungsten diselenide, tungsten disulfide, black phosphorus, Mxene, molybdenum ditelluride, and tungsten trioxide, preferably one or more of graphene oxide, vermiculite, boron nitride, and molybdenum disulfide, further preferably one or more of graphene oxide, vermiculite, and boron nitride, and more preferably graphene oxide.

[0048] In a preferred embodiment, the average size of the two-dimensional layered material ≥500 nm, preferably 500 - 800 nm. Specifically, the size of the two-dimensional layered material described in the present invention refers to the maximum value of the length between the two sides of the surface of the two-dimensional layered material in the two-dimensional expansion direction. For the explanation of the size of the two-dimensional layered material, reference can be made to Figure 3 for understanding.

[0049] In the present invention, the added ionic regulator can directly regulate the flexoelectric effect in the two-dimensional layered material, thereby accelerating the migration rate of ions in the two-dimensional layered material, making the acoustic sensor more accurate and excellent in performance for sound. The ionic regulator is selected from one or more of polystyrene sulfonic acid, polyethylene glycol, poly(diallyldimethylammonium chloride), carboxyvinyl copolymer, polyvinyl sulfonic acid, polymethacrylic acid, polyvinyl phosphoric acid, polyvinylamine, sodium alginate, silk fibroin, carboxylated nanofibers, preferably one or more of polystyrene sulfonic acid, polymethacrylic acid, poly(diallyldimethylammonium chloride) and carboxyvinyl copolymer, further preferably one or more of polystyrene sulfonic acid, polymethacrylic acid and poly(diallyldimethylammonium chloride), and more preferably polystyrene sulfonic acid. Specifically, the carboxyvinyl copolymer can be a common commercially available product, such as carbomer 940.

[0050] In a preferred embodiment, in order to further increase the ion migration rate of the two-dimensional layered material and thus further improve the performance of the acoustic sensor, in the flexoelectric material layer 202, the weight ratio of the two-dimensional layered material to the ionic regulator is defined as 1:0.02 - 0.08, further preferably 1:0.025 - 0.06, further preferably 1:0.03 - 0.05, and more preferably 1:0.04. Specifically, the weight ratio of the two-dimensional layered material to the ionic regulator can be 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07 or 1:0.08.

[0051] In a preferred embodiment, in the flexoelectric material layer 202, the content of the ionic regulator is 2 - 8 wt%, further preferably 3 - 5 wt%, and more preferably 4 wt%. Specifically, the content of the ionic regulator can be 2 wt%, 3 wt%, 4 wt% or 5 wt%.

[0052] In some preferred embodiments, in order to further improve the accuracy of the acoustic sensor, the thickness of the flexoelectric material layer 202 is defined as 0.5 - 50 μm, further preferably 2 - 20 μm, and more preferably 4 - 10 μm. Specifically, the thickness of the flexoelectric material layer 202 can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 8 μm, 10 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm or 50 μm.

[0053] In some preferred embodiments, when the two-dimensional layered material is graphene oxide and the ionic regulator is polystyrene sulfonic acid, that is, the flexoelectric material layer 202 contains graphene oxide and polystyrene sulfonic acid, the acoustic sensor has higher accuracy for sound at this time. In this embodiment, further preferably, in the flexoelectric material layer 202, the weight ratio of graphene oxide to polystyrene sulfonic acid is 1:0.03 - 0.05.

[0054] The present invention further provides a method for preparing the acoustic sensor, the method comprising:

[0055] (1) Mix a dispersion containing a two-dimensional layered material with the ionic regulator, and then prepare the obtained mixture into a film to obtain a flexoelectric material layer 202;

[0056] (2) Form a first electrode layer 201 and a second electrode layer 201 on the upper surface and the lower surface of the flexoelectric material layer 202 respectively to obtain an acoustic sensing layer;

[0057] (3) Stack and fix the upper support 100, the acoustic sensing layer, and the lower support 300 in sequence from top to bottom.

[0058] In a specific embodiment, in the dispersion containing the two-dimensional layered material, the concentration of the two-dimensional layered material is 0.5 - 4 mg / mL. By limiting the concentration of the two-dimensional layered material, the dosage relationship between the two-dimensional layered material and the ionic regulator in the prepared acoustic sensor is further limited, thereby further improving the performance of the acoustic sensor. Specifically, in the dispersion containing the two-dimensional layered material, the concentration of the two-dimensional layered material can be 0.5 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, or 4 mg / mL.

[0059] In a specific embodiment, in step (1), the specific method for preparing the thin film is not limited, and a suitable method can be selected according to the composition and properties of the two-dimensional layered material actually used.

[0060] In a specific embodiment, in step (2), the formation methods of the first electrode layer 201 and the second electrode layer 203 on the upper surface and the lower surface of the flexoelectric material layer 202 are not limited, and it is only necessary to form the first electrode layer 201 on the upper surface of the flexoelectric material layer 202 and form the second electrode layer 203 on the lower surface of the flexoelectric material layer 202. The specific method can be selected according to the composition of the two-dimensional layered material used.

[0061] In some specific embodiments, the first electrode layer 201 and the second electrode layer 203 can be formed on the upper surface and the lower surface of the flexoelectric material layer 202 by spraying or sputtering. The specific process of spraying or sputtering can be implemented with reference to the conventional technical methods in the art.

[0062] In a specific embodiment, the upper support 100, the acoustic sensing layer, and the lower support 300 are stacked in sequence from top to bottom. The acoustic sensing layer is placed to cover the hollow parts of the upper support 100 and the lower support 300, and then fixed through the connecting components 500 provided on the upper support 100 and the lower support 300. After fixing, the acoustic sensor can be prepared.

[0063] In some specific embodiments, the specific process of the method for preparing the acoustic sensor includes: mixing the dispersion liquid containing the two-dimensional layered material with the ion regulator, and then coating the obtained mixed liquid on the surface of the first electrode layer 201 to obtain a component containing the first electrode layer 201 and the flexoelectric material layer 202. Then, a second electrode layer 203 is formed on the surface of the flexoelectric material layer 202 to obtain the acoustic sensing layer; the upper support 100, the acoustic sensing layer, and the lower support 300 are stacked and fixed in sequence from top to bottom.

[0064] In some specific embodiments, the specific process of the method for preparing the acoustic sensor includes: mixing the dispersion liquid containing the two-dimensional layered material with the ion regulator, and then filtering the obtained mixed liquid into a film to obtain the flexoelectric material layer 202; then, a first electrode layer 201 is formed on the upper surface of the flexoelectric material layer 202, and a second electrode layer 203 is formed on the lower surface of the flexoelectric material layer 202 to obtain the acoustic sensing layer; the upper support 100, the acoustic sensing layer, and the lower support 300 are stacked and fixed in sequence from top to bottom.

[0065] In some specific embodiments, the specific process of the method for preparing the acoustic sensor includes: mixing the dispersion liquid containing the two-dimensional layered material with the ion regulator, and then coating the obtained mixed liquid on a substrate, drying and separating the film from the substrate to obtain the flexoelectric material layer 202; then, a first electrode layer 201 is formed on the upper surface of the flexoelectric material layer 202, and a second electrode layer 203 is formed on the lower surface of the flexoelectric material layer 202 to obtain the acoustic sensing layer; the upper support 100, the acoustic sensing layer, and the lower support 300 are stacked and fixed in sequence from top to bottom.

[0066] In a preferred embodiment, the method further includes: regulating the flexoelectric effect of the two-dimensional layered material by adjusting the dosage of the ionic regulator. Specifically, during the actual preparation process, the flexoelectric effect of the selected two-dimensional layered material can be adjusted by the dosage of the added ionic regulator until the flexoelectric effect of the two-dimensional layered material meets the product requirements.

[0067] The acoustic sensor described in the present invention has a simple structure and can be obtained only by assembling a support member and an acoustic sensing layer. It has fewer components and is more conducive to miniaturization. At the same time, the acoustic sensor described in the present invention utilizes the flexoelectric effect possessed by the flexoelectric material layer in the acoustic sensing layer, which can convert high-frequency sound signals into electrical signals. And due to the high electrical output of the flexoelectric material layer, the collection of sound is more convenient. Therefore, the acoustic sensor has a higher recognition accuracy for human voices, a smaller Euclidean distance, and more excellent performance, and has a broader application prospect.

[0068] The following further illustrates the acoustic sensor and its preparation method described in the present invention through examples. The examples are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0069] The experimental methods in the following examples are all conventional methods in the art unless otherwise specified. The experimental materials used in the following examples can all be commercially obtained unless otherwise specified. The structural schematic diagrams of the acoustic sensors prepared in the following examples and comparative examples are as Figure 1 shown, in which the structural schematic diagrams of the upper support 100 and the lower support 300 are as Figure 2 shown.

[0070] Among them, the carboxyvinyl copolymer used in the following examples and comparative examples is Carbopol 940.

[0071] Example 1

[0072] (1) Add 6 milligrams of graphene oxide (average size of 600 nm) to 3 milliliters of deionized water, and ultrasonically disperse for 15 minutes to obtain a dispersion. The concentration of graphene oxide in the dispersion is 2 milligrams per milliliter; then add 0.24 milligrams of polystyrene sulfonic acid to the above dispersion, and magnetically stir for 20 minutes to obtain a mixture;

[0073] (2) Divide the completed mixed solution into three portions, each portion being 1 milliliter, and scrape and coat it on the gold electrode. Dry the moisture in an oven at 40 degrees Celsius to obtain a component containing a flexoelectric material layer 202 (with a polystyrene sulfonic acid content of 4 wt%) and a first electrode layer 201, where the thickness of the flexoelectric material layer 202 is 2 micrometers; then sputter a gold electrode on the flexoelectric material layer as the second electrode layer 203, and obtain an acoustic sensing layer after sputtering is completed;

[0074] (3) Stack and fix the upper support 100, the acoustic sensing layer, and the lower support 300 in sequence from top to bottom to obtain an acoustic sensor.

[0075] Example 2

[0076] (1) Add 6 milligrams of boron nitride nanosheets (with an average size of 500 nm) to 12 milliliters of ethanol, and ultrasonically disperse for 15 minutes to obtain a dispersion liquid, where the concentration of boron nitride nanosheets in the dispersion liquid is 0.5 milligram per milliliter; then add 0.12 milligram of polyethylene glycol to the above dispersion liquid and magnetically stir for 20 minutes to obtain a mixed solution;

[0077] (2) Directly filter the completed mixed solution by suction to obtain a boron nitride nanosheet film, that is, obtain a flexoelectric material layer 202 (with a polyethylene glycol content of 2 wt%), with a thickness of 1 micrometer; then spray carbon nanotubes on the upper surface of the flexoelectric material layer 202 as the first electrode layer 201, and spray carbon nanotubes on the lower surface of the flexoelectric material layer 202 as the second electrode layer 203, and obtain an acoustic sensing layer after spraying is completed;

[0078] (3) Stack and fix the upper support 100, the acoustic sensing layer, and the lower support 300 in sequence from top to bottom to obtain an acoustic sensor.

[0079] Example 3

[0080] (1) Add 6 milligrams of vermiculite nanosheets (with an average size of 800 nm) to 1.5 milliliters of ethanol, and ultrasonically disperse for 15 minutes to obtain a dispersion liquid, where the concentration of vermiculite nanosheets in the dispersion liquid is 4 milligrams per milliliter; then add 0.48 milligram of carboxyvinyl copolymer to the above dispersion liquid and magnetically stir for 20 minutes to obtain a mixed solution;

[0081] (2) Directly scrape and coat the completed mixed solution to obtain a vermiculite nanosheet film, that is, obtain a flexoelectric material layer 202 (with a carboxyvinyl copolymer content of 8 wt%), with a thickness of 5 micrometers; then sputter a silver electrode on the upper surface of the flexoelectric material layer 202 as the first electrode layer 201, and sputter a silver electrode on the lower surface of the flexoelectric material layer 202 as the second electrode layer 203, and obtain an acoustic sensing layer after sputtering is completed;

[0082] (3) Stack and fix the upper support body 100, the acoustic sensing layer, and the lower support body 300 in sequence from top to bottom to obtain an acoustic sensor.

[0083] Example 4

[0084] (1) Add 6 milligrams of molybdenum disulfide nanosheets (average size of 500 nm) to 6 milliliters of water, and ultrasonically disperse for 15 minutes to obtain a dispersion. The concentration of molybdenum disulfide nanosheets in the dispersion is 1 milligram per milliliter; then add 0.3 milligrams of polydiallyldimethylammonium chloride to the above dispersion, and magnetically stir for 20 minutes to obtain a mixture.

[0085] (2) Directly filter the dispersed mixture by suction to obtain a molybdenum disulfide nanosheet film, that is, obtain the flexoelectric material layer 202 (the content of polydiallyldimethylammonium chloride is 5 wt%), with a thickness of 1.5 micrometers; then spray silver nanowire electrodes on the upper surface of the flexoelectric material layer 202 as the first electrode layer 201, and spray silver nanowire electrodes on the lower surface of the flexoelectric material layer 202 as the second electrode layer 203. After spraying, obtain the acoustic sensing layer.

[0086] (3) Stack and fix the upper support body 100, the acoustic sensing layer, and the lower support body 300 in sequence from top to bottom to obtain an acoustic sensor.

[0087] Comparative Example 1

[0088] Implement according to the method of Example 1, the difference is that the concentration of graphene oxide in the dispersion is 5 milligrams per milliliter, and the weight ratio of graphene oxide to polydiallyldimethylammonium chloride is 1:0.01.

[0089] Comparative Example 2

[0090] (1) Add 14 milligrams of graphene oxide (average size of 200 nm) to 6 milliliters of deionized water, and ultrasonically disperse for 15 minutes to obtain a dispersion. The concentration of graphene oxide in the dispersion is 2 milligrams per milliliter; then add 0.14 milligrams of polystyrene sulfonic acid to the above dispersion, and magnetically stir for 20 minutes to obtain a mixture.

[0091] (2) Directly scrape the dispersed mixture to obtain a graphene oxide film, that is, obtain the flexoelectric material layer 202 (the content of polystyrene sulfonic acid is 1 wt%), with a thickness of 7 micrometers; then sputter gold electrodes on the upper surface of the flexoelectric material layer 202 as the first electrode layer 201, and sputter gold electrodes on the lower surface of the flexoelectric material layer 202 as the second electrode layer 203. After sputtering, obtain the acoustic sensing layer.

[0092] (3) Stack and fix the upper support body 100, the acoustic sensing layer, and the lower support body 300 in sequence from top to bottom to obtain an acoustic sensor.

[0093] Comparative Example 3

[0094] (1) Add 2 mg of vermiculite nanosheets (average size of 900 nm) to 10 mL of water, and ultrasonically disperse for 15 minutes to obtain a dispersion. The concentration of vermiculite nanosheets in the dispersion is 0.2 mg / mL; then add 0.08 mg of polystyrene sulfonic acid to the above dispersion, and magnetically stir for 20 minutes to obtain a mixture.

[0095] (2) Directly filter the dispersed mixture by suction to obtain a vermiculite nanosheet film, that is, obtain the flexoelectric material layer 202 (the content of polystyrene sulfonic acid is 4 wt%), with a thickness of 0.3 μm; then sputter a gold electrode on the upper surface of the flexoelectric material layer 202 as the first electrode layer 201, and sputter a gold electrode on the lower surface of the flexoelectric material layer 202 as the second electrode layer 203. After sputtering, obtain the acoustic sensing layer.

[0096] (3) Stack and fix the upper support body 100, the acoustic sensing layer, and the lower support body 300 in sequence from top to bottom to obtain an acoustic sensor.

[0097] Comparative Example 4

[0098] Carry out according to the method of Example 1, except that in the preparation process, the ionic regulator polystyrene sulfonic acid is not added.

[0099] Comparative Example 5

[0100] Carry out according to the method of Example 1, except that in the preparation process, graphene oxide is replaced with an equal weight of polyethylene glycol diacrylate.

[0101] Comparative Example 6

[0102] Carry out according to the method of Example 1, except that in the preparation process, the ionic regulator polystyrene sulfonic acid is replaced with an equal weight of polyurethane.

[0103] Test Example

[0104] Test the performance of the acoustic sensors and acoustic sensing layers prepared in Examples 1-4 and the products prepared in Comparative Examples 1-6.

[0105] Flexoelectric ionic electrical output performance test method: In an environment with a relative humidity of 80%, bend the acoustic sensing layers prepared in the examples and comparative examples to test the flexoelectric ionic electrical output. The test results are expressed in terms of current and voltage, and the results are shown in Table 1.

[0106] Method for testing sound accuracy of acoustic sensor: In an environment with a relative humidity of 80%, place the acoustic sensors prepared in the examples and comparative examples in front of the horn of a speaker. Play a standard sound with a sound pressure of 118 dB through the speaker, and record the electrical signals output by the device. The results are shown in Table 1.

[0107] Table 1

[0108] Example Number Current (μA) Voltage (mV) <![CDATA[Curvature range (m -1 )]]> Frequency Range (kHz) Sound Accuracy Rate Example 1 16.7 18.6 54-90 0.02-5 0.7 Example 2 6.2 7.0 54-82 0.02-5 0.51 Example 3 8.7 10.2 54-82 0.02-5 0.57 Example 4 7.8 5.2 54-82 0.02-5 0.48 Comparative Example 1 0.8 1.2 54-64 0.5-2 0.12 Comparative Example 2 0.2 0.5 54-64 1 0.08 Comparative Example 3 / / / / / Comparative Example 4 2.2 1.34 54-82 0.5-2 0.22 Comparative Example 5 0.25 0.18 54-82 0.02-0.1 0.05 Comparative Example 6 2.5 1.85 54-64 0.02-2 0.29

[0109] Note: In Comparative Example 3, since it was too thin and the upper and lower electrodes were electrically connected, testing could not be carried out and test results could not be obtained.

[0110] As can be seen from Table 1, the flexural ion electrical output of the acoustic sensor described in the present invention is more rapid, has more excellent sound accuracy rate, and the structure of the acoustic sensor described in the present invention is simpler, consisting of only three components, and has a broader market application prospect.

[0111] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. An acoustic sensor, characterized in that: The acoustic sensor comprises an upper support body (100), an acoustic sensing layer and a lower support body (300); Wherein, the upper support body (100) and the lower support body (300) are respectively provided with hollow parts (400), and the acoustic sensing layer covers the hollow parts (400) and is located between the upper support body (100) and the lower support body (300); The acoustic sensing layer comprises a first electrode layer (201), a flexoelectric material layer (202) and a second electrode layer (203) which are stacked in sequence; The flexoelectric material layer (202) contains a two-dimensional layered material and an ion regulator; Wherein, the two-dimensional layered material is selected from one or more of graphene oxide, boron nitride, vermiculite, molybdenum disulfide, tungsten diselenide, tungsten disulfide, black phosphorus, Mxene, molybdenum ditelluride and tungsten trioxide; The ion regulator is selected from one or more of polystyrene sulfonic acid, polyethylene glycol, polydiallyldimethylammonium chloride, carboxyethylene copolymer, polyethylene sulfonic acid, polymethacrylic acid, polyvinyl phosphoric acid, polyethylene amine, sodium alginate, silk fibroin and carboxylated nanofibers; The weight ratio of the two-dimensional layered material to the ion regulator is 1:0.02-0.08; The thickness of the flexoelectric material layer (202) is 0.5-50 μm.

2. The acoustic sensor according to claim 1, characterized in that: The two-dimensional layered material is selected from one or more of graphene oxide, boron nitride, vermiculite, and molybdenum disulfide, and the ion regulator is selected from one or more of polystyrene sulfonic acid, polyethylene glycol, polydiallyldimethylammonium chloride, and carboxyethylene copolymer.

3. The acoustic sensor according to claim 1, characterized in that: The average size of the two-dimensional layered material is ≥500 nm, preferably 500-800 nm.

4. The acoustic sensor according to claim 1 or 2, characterized in that: The flexoelectric material layer (202) contains graphene oxide and polystyrene sulfonic acid; Preferably, in the flexoelectric material layer (202), the weight ratio of the graphene oxide to the polystyrene sulfonic acid is 1:0.03-0.

05.

5. The acoustic sensor according to any one of claims 1 to 4, characterized in that: In the flexoelectric material layer (202), the content of the ion regulator is 2-8 wt%.

6. The acoustic sensor according to any one of claims 1 to 5, characterized in that: The first electrode layer (201) is selected from one of a gold electrode, a silver electrode, a copper electrode, an aluminum electrode, a silver nanowire electrode, a carbon fiber electrode and a carbon nanotube electrode.

7. The acoustic sensor according to any one of claims 1 to 6, characterized in that: The second electrode layer (203) is selected from one of a gold electrode, a silver electrode, a copper electrode, an aluminum electrode, a silver nanowire electrode, a carbon fiber electrode and a carbon nanotube electrode.

8. The acoustic sensor according to any one of claims 1 to 7, characterized in that: The upper support body (100) and the lower support body (300) are made of polymethyl methacrylate.

9. A method for preparing the acoustic sensor according to any one of claims 1 to 8, characterized in that: The method comprises: (1) mixing a dispersion containing a two-dimensional layered material with the ion regulator, and then preparing the obtained mixed solution into a film to obtain a flexoelectric material layer (202); (2) forming a first electrode layer (201) and a second electrode layer (203) on the upper surface and the lower surface of the flexoelectric material layer (202), respectively, to obtain an acoustic sensing layer; (3) stacking and fixing the upper support body (100), the acoustic sensing layer and the lower support body (300) in order from top to bottom; In the dispersion containing the two-dimensional layered material, the concentration of the two-dimensional layered material is 0.5-4 mg / mL.

10. The method according to claim 9, characterized in that The method further comprises: regulating the flexo-ionic electric effect of the two-dimensional layered material by adjusting the dosage of the ion regulator.

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