Graphene stretchable sound-emitting device based on thermoacoustic effect and related components

Abstract

The application provides a graphene stretchable sound emitting device based on a thermoacoustic effect and related components, and the graphene stretchable sound emitting device comprises a substrate, a graphene dielectric layer, contact metal and a wire medium; the substrate is a stretchable structure, the graphene dielectric layer is a three-dimensional structure layer formed by printing and permeating graphene mixed with deionized water ink into the substrate, the contact metal is arranged on the substrate and located on both sides of the graphene dielectric layer, one end of the wire medium is arranged in the contact metal, and the other end of the wire medium is connected with an output end of an audio player. The graphene stretchable sound emitting device has good stretchability and strong practicability.

Description

Technical Field

[0001] This invention relates to the field of sound-generating device technology, and in particular to a graphene stretchable sound-generating device and related components based on the thermoacoustic effect. Background Technology

[0002] Unlike silicon-based electronics, biological life forms are soft, flexible, and resilient. With the development of electronic information technology, humanity needs electronic technologies that break through mechanical limitations, combining electronics with wearable and implantable devices to achieve a more convenient and comfortable experience. As the demand for wearable devices grows, new requirements are being placed on the performance of electronic devices under bending, stretching, compression, and torsion conditions, while maintaining their initial high performance, reliability, and high integration.

[0003] Graphene has also attracted attention in the field of thermoacoustics due to its excellent physical, chemical, electrical, and mechanical properties. Flexible acoustic devices based on graphene can achieve a sound pressure level (SPL) of 40 dB in the ultrasonic range (50 kHz), demonstrating superior sound performance in wearable devices. However, existing graphene acoustic devices are formed by oxidation-reduction on PET (polyethylene terephthalate) or PDMS (polydimethylsiloxane) substrates using etching processes, which makes it difficult to achieve stretchability and limits their practicality. Summary of the Invention

[0004] This invention provides a graphene stretchable sound-generating device and related components based on the thermoacoustic effect, which solves the problem that graphene acoustic devices are difficult to stretch in the prior art. The graphene and deionized water mixed ink is directly printed on the substrate by a two-dimensional material printer, and the ink penetrates the substrate network to form an embedded three-dimensional structure, thereby realizing the stretchability of the graphene acoustic device.

[0005] This invention provides a graphene stretchable sound-generating device based on thermoacoustic effect, comprising a substrate, a graphene dielectric layer, a contact metal, and a conductive medium; the substrate is a stretchable structure, the graphene dielectric layer is a three-dimensional structure layer formed by printing graphene / deionized water mixed ink into the substrate, the contact metal is disposed on the substrate and located on both sides of the graphene dielectric layer, one end of the conductive medium is disposed in the contact metal, and the other end of the conductive medium is connected to the output terminal of an audio player.

[0006] According to the present invention, a graphene stretchable sound-generating device based on the thermoacoustic effect is provided. The resistance and tensile stress of the graphene stretchable sound-generating device satisfy the tensile sound-generating negative electric field model, wherein the tensile sound-generating negative electric field model is as follows:

[0007] In stage one, the resistance increases, and the sound pressure level decreases.

[0008]

[0009] In stage two, the resistance decreases and the sound pressure level increases.

[0010]

[0011] Stage 3: Resistance increases, sound pressure level decreases.

[0012]

[0013] Among them, R g R is the function relating the resistance of the device to the stress in stage one. g0 κ1 is the resistivity of the graphene layer in its initial state, ε is the modulus describing the deformation of the fabric material in the first stage, and ρ is the stress value. rms The sound pressure level is γ, the thermal conductivity of air is e. g For air heat capacity, e s The heat capacity of the substrate is given by q0, and the power flux density is given by v. g e is the speed of sound in air. c The heat capacity of the graphene layer, k c ρ is the thermal conductivity of graphene, β is the mass-dependent constant, R is the corresponding device resistance function in each stage, l is the length of the device, ρ is the resistivity of graphene, and C is the thermal conductivity of graphene. s d is the thermal conductivity of graphene, d is the thickness of the graphene film, and c is the thermal conductivity of graphene. ρ R is the specific heat capacity of graphene. B,x R is the function relating the resistance and stress of the device in stage two or stage three. B,x0 κ2 is the resistance value of the device at the end of stage one, ε is the modulus describing the deformation of the fabric material in stage two. x0 ε is the stress value at which the resistance begins to decrease as tensile stress increases. x1 β is the stress value at which the resistance begins to rise again when the tensile stress increases. x This refers to the relevant quantities of the material and weaving method of the fabric in the X direction.

[0014] The present invention also provides a pre-amplifier driving circuit, including an audio modulation module and an operational amplifier module; the input terminal of the audio modulation module is connected to the output terminal of an audio player, and the output terminal of the audio modulation module is connected to the input terminal of the operational amplifier module, for pulse density modulation of the voltage of the audio signal output by the audio player to obtain a pulse density modulated signal; the output terminal of the operational amplifier module is connected to the input terminal of the graphene stretchable sound-generating device, for amplifying the voltage of the pulse density modulated signal to obtain a sound signal, so as to drive the graphene stretchable sound-generating device to emit sound.

[0015] According to the present invention, a pre-amplifier driving circuit further includes a first DC power supply and a second DC power supply, wherein the first DC power supply is used to power the audio modulation module and the second DC power supply is used to power the operational amplifier module.

[0016] According to the present invention, a pre-amplifier driving circuit is provided, wherein the audio modulation module is model SSM2377.

[0017] According to the present invention, a pre-amplifier driving circuit is provided, wherein the operational amplifier module is model OPA2674.

[0018] According to a pre-amplifier driving circuit provided by the present invention, the audio modulation module includes a three-stage Σ-Δ output modulation module, a 12dB gain module, and a FET voltage driving module; the input terminal of the three-stage Σ-Δ output modulation module serves as the input terminal of the audio modulation module, the output terminal of the three-stage Σ-Δ output modulation module is connected to the input terminal of the 12dB gain module, the output terminal of the 12dB gain module is connected to the input terminal of the FET voltage driving module, and the output terminal of the FET voltage driving module serves as the output terminal of the audio modulation module.

[0019] According to a pre-amplifier driving circuit provided by the present invention, the operational amplifier module is a two-stage operational amplifier, the input terminal of the two-stage operational amplifier serves as the input terminal of the operational amplifier module, and the output terminal of the two-stage operational amplifier serves as the output terminal of the operational amplifier module.

[0020] The present invention also provides a graphene stretchable sound generation system based on thermoacoustic effect, including the graphene stretchable sound generation device based on thermoacoustic effect described above, the pre-sound generation driving circuit described above, and further including an audio player and an audio adapter board; the audio player is used to input audio signals to the pre-sound generation driving circuit through the audio adapter board.

[0021] This invention also provides a method for preparing a graphene stretchable sound-generating device based on thermoacoustic effect, comprising: Step 1: Pre-stretching a substrate regularly in both the transverse and longitudinal directions on a two-dimensional material printer platform by physical fixation; Step 2: Setting printing parameters in computer software, mixing aqueous graphene and deionized water in a 2:3 ratio to obtain printing ink, injecting it into a printing needle, and starting the program to print twice continuously on the sample obtained in Step 1 to obtain a graphene dielectric layer; Step 3: Uniformly distributing contact metal on both sides of the graphene dielectric layer obtained in Step 2; Step 4: Placing one end of a wire dielectric in the contact metal obtained in Step 3; Step 5: Baking the sample obtained in Step 4 at a temperature of 60℃-70℃ for 4-6 hours to obtain the graphene stretchable sound-generating device based on thermoacoustic effect.

[0022] This invention provides a graphene stretchable sound-generating device and related components based on the thermoacoustic effect. The graphene stretchable sound-generating device includes a substrate, a graphene dielectric layer, a conductive dielectric, and a contact metal. The substrate has a stretchable structure. The graphene dielectric layer is a three-dimensional structure layer formed by printing graphene and deionized water mixed ink into the substrate. The contact metal is disposed on the substrate and located on both sides of the graphene dielectric layer. One end of the conductive dielectric is disposed in the contact metal, and the other end of the conductive dielectric is connected to the output terminal of an audio player. The graphene stretchable sound-generating device of this invention has good stretchability and strong practicality. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a cross-sectional view of a graphene stretchable sound-generating device based on the thermoacoustic effect provided by the present invention;

[0025] Figure 2 This is a top view of a graphene stretchable sound-generating device based on the thermoacoustic effect provided by the present invention.

[0026] Figure 3 This is a schematic diagram of the test results for a graphene stretchable sound-generating device based on the thermoacoustic effect provided by the present invention. Figure 1 ;

[0027] Figure 4 This is a schematic diagram of the test results for a graphene stretchable sound-generating device based on the thermoacoustic effect provided by the present invention. Figure 2 ;

[0028] Figure 5 This is a schematic diagram of the test results for a graphene stretchable sound-generating device based on the thermoacoustic effect provided by the present invention. Figure 3 ;

[0029] Figure 6 This is a schematic diagram of the test results for a graphene stretchable sound-generating device based on the thermoacoustic effect provided by the present invention. Figure 4 ;

[0030] Figure 7 This is a schematic diagram of the structure of a graphene stretchable sound generation system based on the thermoacoustic effect provided by the present invention;

[0031] Figure 8 This is a schematic diagram illustrating the principle of a method for fabricating a graphene stretchable sound-generating device based on the thermoacoustic effect, provided by the present invention.

[0032] Figure label:

[0033] 1: Graphene stretchable sound-generating device; 101: Substrate; 102: Graphene dielectric layer; 103: Contact metal; 104: Conductor dielectric; 2: Microphone; 3: Sound card; 701: Audio player; 702: Audio adapter board; 703: Three-stage Σ-Δ output modulation module; 704: 12dB gain module; 705: FET voltage drive module; 706: First DC power supply; 707: Second DC power supply; 708: Two-stage operational amplifier; 801: Two-dimensional material printer; 802: Printing ink; 803: Silver paste; 804: Copper conductor; 805: Heat lamp. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0035] The following is combined with Figures 1-8 This invention describes a graphene stretchable sound-generating device and related components based on the thermoacoustic effect.

[0036] Please refer to Figure 1 , Figure 1 A cross-sectional view of a graphene stretchable sound-generating device based on the thermoacoustic effect provided by the present invention.

[0037] Please refer to Figure 2 , Figure 2This is a top view of a graphene stretchable sound-generating device based on the thermoacoustic effect provided by the present invention.

[0038] This invention provides a graphene stretchable sound-generating device 1 based on thermoacoustic effect, comprising a substrate 101, a graphene dielectric layer 102, a contact metal 103, and a conductive medium 104; the substrate 101 is a stretchable structure, the graphene dielectric layer 102 is a three-dimensional structure layer formed by printing graphene and deionized water mixed ink into the substrate 101, the contact metal 103 is disposed on the substrate 101 and located on both sides of the graphene dielectric layer 102, one end of the conductive medium 104 is disposed in the contact metal 103, and the other end of the conductive medium 104 is connected to the output end of an audio player 701.

[0039] Considering the application requirements of sound-generating devices in the wearable field, and given graphene's excellent electron mobility, thermal conductivity, and acoustic properties, making it an ideal acoustic material, numerous acoustic devices based on this material are currently being developed. Thermoacoustic devices based on flexible graphene are also emerging. However, to achieve wearable functionality, new requirements are placed on the performance of electronic devices under flexible, stretchable, and compressible / torsional forms, while maintaining their initial high performance, reliability, and high integration. There is still a gap in the transition of existing graphene sound-generating devices from flexible to stretchable acoustic devices.

[0040] To address the technical problems existing in the prior art, this invention provides a graphene stretchable sound-generating device 1 based on the thermoacoustic effect. This device can be directly printed onto a clothing substrate using a two-dimensional material printer 801, facilitating integration and large-scale fabrication. By combining a suitable mixture of aqueous graphene and deionized water ink with the substrate, high sound generation performance, stretchability, and performance stability can be achieved. Specifically, the graphene stretchable sound-generating device 1 includes a substrate 101, a graphene dielectric layer 102, a contact metal 103, and a conductive dielectric 104. The substrate 101 can be a stretchable structure, obtained from a cross-woven cotton fabric, possessing high water absorption, elasticity, and stretchability. The graphene dielectric layer 102 can be a three-dimensional structure layer formed by printing graphene and deionized water mixed ink into the substrate 101. The contact metal 103 is placed on the substrate 101 and located on both sides of the graphene dielectric layer 102. Finally, one end of the wire medium 104 is placed in the contact metal 103, and the other end of the wire medium 104 is connected to the output end of the audio player 701. Thus, a stretchable graphene thermoacoustic device can be obtained. The audio player 701 outputs an audio signal to drive the device to produce sound. The overall structure is simple and highly practical.

[0041] Furthermore, the substrate 101 can be a pre-stretched fabric that is physically fixed on the printer platform; the graphene ink of the graphene dielectric layer 102 is made by mixing aqueous graphene and deionized water in a 2:3 ratio, and the two-dimensional material printer 801 directly prints the ink twice continuously according to the program settings. The size of the device is set by the program of the two-dimensional material printer 801, and multiple devices can be fabricated at one time; after connecting the wire medium 104, it can be baked in a baking lamp 805 at 60℃-70℃ for 4-6 hours; the wire medium 104 can be made of an active metal such as Cu, and the contact metal 103 can be made of an active metal such as Ag or Au.

[0042] In summary, the graphene stretchable sound-generating device 1 based on the thermoacoustic effect provided by this invention has good stretchability and strong practicality.

[0043] Based on the above embodiments:

[0044] As a preferred embodiment, the resistance and tensile stress of the graphene stretchable sound-generating device satisfy the tensile sound-generating negative electric field model, which is as follows:

[0045] In stage one, the resistance increases, and the sound pressure level decreases.

[0046]

[0047] In stage two, the resistance decreases and the sound pressure level increases.

[0048]

[0049] Stage 3: Resistance increases, sound pressure level decreases.

[0050]

[0051] Among them, R g R is the function relating the resistance of the device to the stress in stage one. g0 κ1 is the resistivity of the graphene layer in its initial state, ε is the modulus describing the deformation of the fabric material in the first stage, and ρ is the stress value. rms The sound pressure level is γ, the thermal conductivity of air is e. g For air heat capacity, e s The heat capacity of the substrate is given by q0, and the power flux density is given by v. g e is the speed of sound in air. c The heat capacity of the graphene layer, k c ρ is the thermal conductivity of graphene, β is the mass-dependent constant, R is the corresponding device resistance in each stage, l is the length of the device, ρ is the resistivity of graphene, and C is the thermal conductivity of graphene. s d is the thermal conductivity of graphene, d is the thickness of the graphene film, and c is the thermal conductivity of graphene. ρR is the specific heat capacity of graphene. B,x R is the function relating the resistance and stress of the device in stage two or stage three. B,x0 κ2 is the resistance value of the device at the end of stage one, ε is the modulus describing the deformation of the fabric material in stage two. x0 ε is the stress value at which the resistance begins to decrease as tensile stress increases. x1 β is the stress value at which the resistance begins to rise again when the tensile stress increases. x This refers to the relevant quantities of the material and weaving method of the fabric in the X direction.

[0052] Please refer to Figure 3 , Figure 3 A schematic diagram of test results for a graphene stretchable sound-generating device based on the thermoacoustic effect provided by this invention. Figure 1 .

[0053] Please refer to Figure 4 , Figure 4 A schematic diagram of test results for a graphene stretchable sound-generating device based on the thermoacoustic effect provided by this invention. Figure 2 .

[0054] Please refer to Figure 5 , Figure 5 A schematic diagram of test results for a graphene stretchable sound-generating device based on the thermoacoustic effect provided by this invention. Figure 3 .

[0055] Please refer to Figure 6 , Figure 6 A schematic diagram of test results for a graphene stretchable sound-generating device based on the thermoacoustic effect provided by this invention. Figure 4 .

[0056] In terms of sound performance, a fixed-frequency sound test was conducted on the last ten cycles of every hundred of the 100 stretching cycles, with an input audio frequency of 15kHz. The test results showed a periodic and stable change, and also a phenomenon similar to a negative charge group.

[0057] Combining the graphene stretching negative charge model and the sound generation formula, the sound generation effect is closely related to the graphene density. During the stretching process, due to the density of the fabric and the breakage and recombination of surface devices, the density of graphene through which the current flows changes. At the same time, the change in resistance can be directly measured, thus establishing a correlation between density and resistance, and thereby establishing a stretching negative charge sound generation model.

[0058] (1) For a stretching device, the resistance of the device increases with the degree of stretching. Where R g R is the function relating the resistance of the device to the stress in stage one. g0κ1 is the resistance value of the graphene layer in the initial state, κ1 is the modulus describing the deformation of the fabric material in the first stage, and ε is the stress value.

[0059] (2) Further stretching of the device creates a conductive path inside, generating a negative charge effect. Among them, R B,x ε is the function relating the resistance and stress of the device in stage two or stage three. B0 R represents the strain in the initial state, κ2 is the modulus describing the deformation of the fabric material in the second stage; B，x0 The resistance value of the device at the end of stage one, ε x0 This is the stress value at which the resistance begins to decrease as tensile stress increases;

[0060] (3) Upon further stretching, the resistance increases with the degree of stretching. B，x =R B，x |ε=ε x1 ·[1+(ε-ε x1 )β x ]. Among them, R B，x R is the function relating the resistance and stress of the device in stage two or stage three. B，x |ε is the resistance value R B，x It is a function of the stress value ε, ε x1 β is the stress value at which the resistance begins to increase again when the tensile stress increases. x This represents the relevant quantities of the fabric material and weaving method in the X direction. Meanwhile, the thermoacoustic generation formula is... Where q0 is the power flux density, p rms e represents the sound pressure level. s e represents the heat capacity of the substrate. c e represents the heat capacity of the graphene layer. g Let f be the air heat capacity, f be the audio signal frequency, and α be the frequency. s L is the thermal diffusivity of the substrate. s Where γ is the thickness of the substrate, γ is the thermal conductivity of air, and v g The speed of sound in air. Let C be the heat capacity of material i. Meanwhile, C... s =dρ c c ρ , d represents the thickness of the graphene film, k c ρ is the thermal conductivity coefficient of graphene. c For the density of graphene, c ρ For the specific heat capacity of graphene, C s is the thermal conductivity of graphene.

[0061] The sound-producing effect is closely related to the density of graphene. During stretching, due to the density of the fabric and the breakage and recombination of surface devices, the density of graphene changes as current flows, and this change in resistance can be directly measured, thus establishing a relationship between density and resistance. The resistivity formula is then simplified. β is a mass-related constant, R is the resistance, d is the width of the device, l is the length of the device, l = l0·(1+ε), where l0 is the initial resistance length of the device, ε is the stress value, and the density formula ρ is also taken into account. C = m / (d·s), where m is the mass of the graphene layer and s is the surface area of ​​the graphene layer. Combined with the resistivity formula R = (ρ·2) / (d·s),... 2 ) / V, where V represents volume, and the resistivity of graphene is ρ = 10. -6 Ω·cm, we can simplify the density to Where β is the mass-related constant. Substituting the above formula into the correction factor, we get: Where C s =dβRc ρ / ρl 2 Representing density with resistance R and combining it with the formula for negative charge groups, we can substitute this into the thermoacoustic formula to obtain a tensile-based negative charge group model for sound generation. Observing the phenomenon, when tensile stress increases, the resistance decreases for a period, resulting in an increase in sound pressure level; conversely, when tensile stress is released, the resistance increases for a period, resulting in a decrease in sound pressure level. From a theoretical perspective, based on the fundamental principle of thermoacoustic generation, when an AC signal passes through a graphene film, it generates Joule heat, which is released into the air. The current generates Joule heat, causing the surrounding air to alternately expand and contract, producing sound waves. (The Joule heating frequency is twice that of the input electrical signal, hence the harmonics.) Experiments show that when the device is subjected to tensile stress, its resistance changes. Simultaneously, as the resistance increases, the internal temperature of the device rises, increasing the thermal conductivity of the graphene film. Subsequently, the ability of heat to propagate into the surrounding air decreases, leading to a lower frequency of expansion and contraction of air molecules, thus reducing sound pressure. On the other hand, as resistance decreases, air molecules move faster, thereby increasing sound pressure. The simulation results and experimental results are in good agreement.

[0062] The present invention also provides a pre-amplifier driving circuit, including an audio modulation module and an operational amplifier module; the input terminal of the audio modulation module is connected to the output terminal of the audio player 701, and the output terminal of the audio modulation module is connected to the input terminal of the operational amplifier module, for pulse density modulation of the voltage of the audio signal output by the audio player 701 to obtain a pulse density modulation signal; the output terminal of the operational amplifier module is connected to the input terminal of the graphene stretchable sound generator 1, for amplifying the voltage of the pulse density modulation signal to obtain a sound signal, so as to drive the graphene stretchable sound generator 1 to emit sound.

[0063] Considering that the graphene stretchable sound-generating device 1 based on the thermoacoustic effect still suffers from low sound pressure level and frequency doubling problem caused by the thermoacoustic effect when emitting sound, this embodiment provides a pre-sound driving circuit, including an audio modulation module and an operational amplifier module. The audio modulation module can perform pulse density modulation on the voltage of the audio signal output by the audio player 701 to obtain a pulse density modulation signal, which at the same time reduces the frequency doubling problem caused by the thermoacoustic effect to a certain extent. Then, the operational amplifier module amplifies the voltage of the pulse density modulation signal to obtain a sound signal to drive the graphene stretchable sound-generating device 1 to emit sound. Compared with the existing graphene stretchable devices, the graphene stretchable sound-generating device 1 in this embodiment has unique sound-generating function and higher sound pressure level.

[0064] In a preferred embodiment, the system further includes a first DC power supply 706 and a second DC power supply 707, wherein the first DC power supply 706 is used to power the audio modulation module and the second DC power supply 707 is used to power the operational amplifier module.

[0065] In this embodiment, the pre-amplifier driving circuit may further include a first DC power supply 706 and a second DC power supply 707. The first DC power supply 706 may be located outside the audio modulation module to power the audio modulation module, and the second DC power supply 707 may be located outside the operational amplifier module to power the operational amplifier module.

[0066] As a preferred embodiment, the audio modulation module is model SSM2377.

[0067] In this embodiment, the audio modulation module can be selected from the SSM2377 chip, which has advantages such as high integration, low power consumption, high precision, fast processing speed and low cost.

[0068] As a preferred embodiment, the operational amplifier module is model OPA2674.

[0069] In this embodiment, the operational amplifier module can be selected from the OPA2674 chip, which has advantages such as high integration, low power consumption, high precision, fast operation speed and low cost.

[0070] In a preferred embodiment, the audio modulation module includes a three-stage Σ-Δ output modulation module 703, a 12dB gain module 704, and a FET voltage drive module 705. The input terminal of the three-stage Σ-Δ output modulation module 703 serves as the input terminal of the audio modulation module, the output terminal of the three-stage Σ-Δ output modulation module 703 is connected to the input terminal of the 12dB gain module 704, the output terminal of the 12dB gain module 704 is connected to the input terminal of the FET voltage drive module 705, and the output terminal of the FET voltage drive module 705 serves as the output terminal of the audio modulation module.

[0071] To further reduce the frequency doubling problem caused by thermoacoustic effects, in this embodiment, the audio modulation module may include a three-stage Σ-Δ output modulation module 703, a 12dB gain module 704, and a FET voltage drive module 705. Specifically, the audio signal input to the audio player 701 is input to the SSM2377 chip through the audio adapter board 702. Since thermoacoustic devices emit sound by heating air, their heating power is proportional to the square of the input signal, i.e., P = I. 2 R, where P is the heating power of the acoustic device, I is the current of the audio signal input to the acoustic device, and R is the resistance of the acoustic device. The audio signal input to the acoustic device is a composite signal containing multiple frequencies. When the audio signal is squared, harmonic signals of multiple harmonics appear, resulting in complete distortion of the device's sound output. The SSM2377 uses three-stage Σ-Δ output modulation to convert the corresponding analog signal into a digital signal, while reducing the harmonic distortion caused by thermoacoustic effects to a certain extent. Unlike pulse width modulators, Σ-Δ modulators do not generate harmonic spikes and reduce the amplitude of high-frequency spectral components, thus reducing EMI (Electromagnetic Interference) radiation and internal oscillations. Then, through the FET (Field Effect Transistor) drive circuit, an electromagnetic suppression structure is used to perform voltage polarity switching, which can prevent voltage transients in the signal output to the OPA2674 when momentarily disconnected or turned on. The FET electromagnetic suppression structure reduces these output transients. This chip adds a 12dB bias to enhance the sound output effect.

[0072] In a preferred embodiment, the operational amplifier module is a two-stage operational amplifier 708, with the input terminal of the two-stage operational amplifier 708 serving as the input terminal of the operational amplifier module, and the output terminal of the two-stage operational amplifier 708 serving as the output terminal of the operational amplifier module.

[0073] To further improve the sound pressure level of the graphene stretchable sound-generating device 1, in this embodiment, the operational amplifier module can be a cascaded two-stage operational amplifier 708, which can amplify the voltage of the pulse density modulation signal in two stages to obtain a sound signal to drive the graphene stretchable sound-generating device 1 to produce sound, resulting in a higher sound pressure level for the device.

[0074] The stretchable graphene thermoacoustic device of the present invention, after circuit modulation and amplification, can achieve a maximum sound pressure level of 75dB.

[0075] Based on the aforementioned circuit, this invention experimentally analyzed the wearability and stretchability of the device from multiple perspectives. First, the device was continuously stretched 4000 times in the X and Y directions, with a frequency sweep test performed every 500 stretches at its original length. The average performance degradation rate at each frequency was 8.94%, indicating relatively stable performance. Considering the continuous bending of elbows, knees, and other joints during normal human activity, and the inevitable stretching of clothing during activity, the device was continuously bent 1000 times and punctured with a sharp object 1000 times. Its frequency sweep sound effect and non-planar sound effect under different bending heights were measured every 200 stretches. The different bending heights were defined as bending radii of 5mm and 12mm, representing the distance from the highest point of the device to the horizontal plane. The device was also continuously washed 5 times, and its sound performance in the dry state was measured. The average rate of change in the experimental results was statistically analyzed. In the X and Y axis stretching, sharp object puncture, bending, washing, and bending tests, the rates were 8.9%, 9.2%, 9.4%, 9.8%, and 6.0%, respectively. The performance change rate did not exceed 10%, indicating good stability. These experiments demonstrate that the stretchable graphene thermoacoustic device of this invention has better sound generation performance compared to existing stretchable devices, and exhibits excellent performance in various anti-destructive and stability tests. This device holds promise for integration into clothing and application in stretchable and wearable systems.

[0076] This invention tests and analyzes the performance of a single cycle during testing. First, the relative change in resistance under 50% stress tension is statistically analyzed. It can be found that the resistance does not increase monotonically with increasing stress, but rather shows a decreasing trend within a certain range. This phenomenon is observed in multiple consecutive cycles.

[0077] Please refer to Figure 7 , Figure 7 This is a schematic diagram of a graphene stretchable sound generation system based on thermoacoustic effect, provided by the present invention.

[0078] The present invention also provides a graphene stretchable sound generation system based on thermoacoustic effect, including the above-mentioned graphene stretchable sound generation device 1 based on thermoacoustic effect, the above-mentioned pre-sound generation driving circuit, and further including an audio player 701 and an audio adapter board 702; the audio player 701 is used to input audio signals to the pre-sound generation driving circuit through the audio adapter board 702.

[0079] In this embodiment, the graphene stretchable sound generation system based on the thermoacoustic effect includes a graphene stretchable sound generation device 1, a pre-amplifier sound generation driver circuit, an audio player 701, and an audio adapter board 702. Audio signals can be directly input through the mobile phone audio player 701. After conversion by the ADC (Analog to Digital Converter) in the pre-amplifier sound generation driver circuit, the signal is modulated by an audio modulator and amplified by an audio amplifier before driving the device to generate sound. The subsequent testing instruments include a microphone 2 and a sound card 3. The microphone 2 collects the sound signal emitted by the graphene stretchable sound generation device 1 and transmits it to the sound card 3 for real-time monitoring. Simultaneously, during fixed-frequency testing, a customized programmable automated stretching instrument can achieve horizontal stretching, facilitating sound pickup by the microphone 2. This instrument's displacement is accurate to 0.03mm, and the number of tests, displacement, and speed can be controlled through programming, achieving repeated stretching up to 10,000 times without generating additional displacement.

[0080] For an introduction to the graphene stretchable sound generation system based on the thermoacoustic effect provided by this invention, please refer to the above device embodiments; the invention will not be described again here.

[0081] Please refer to Figure 8 , Figure 8 This is a schematic diagram illustrating the principle of a method for fabricating a graphene stretchable sound-generating device based on the thermoacoustic effect, as provided by the present invention.

[0082] This invention also provides a method for preparing a graphene stretchable sound-generating device 1 based on the thermoacoustic effect, comprising:

[0083] Step 1: On the 2D material printer 801 platform, the substrate 101 is pre-stretched in a regular manner in the horizontal and vertical directions by physical fixation;

[0084] Step 2: Set the printing parameters on the computer software, mix water-based graphene and deionized water in a ratio of 2:3 to obtain printing ink 802, inject it into the printing needle, start the program and print twice on the sample obtained in step 1 to obtain graphene dielectric layer 102.

[0085] Step 3: The contact metal 103 is uniformly disposed on both sides of the graphene dielectric layer 102 obtained in step 2;

[0086] Step 4: Place one end of the conductor dielectric 104 into the contact metal 103 obtained in step 3;

[0087] Step 5: Bake the sample obtained in Step 4 at a temperature of 60℃-70℃ for 4-6 hours to obtain a graphene stretchable sound-generating device 1 based on thermoacoustic effect.

[0088] The contact metal 103 can be silver paste 803, the conductor medium 104 can be copper conductor 804, and the baking device can be a baking lamp 805.

[0089] Printing parameters can include graphic, device size, printing speed, air pressure, etc.

[0090] The stretchable graphene thermoacoustic device of the present invention has a simple structure and a simple preparation method, which to a certain extent overcomes the contradiction between cost, sound generation effect and stretchability.

[0091] For a description of the method for fabricating a graphene stretchable sound-generating device based on the thermoacoustic effect provided by this invention, please refer to the above device embodiments; the invention will not be repeated here.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A graphene stretchable sound-generating device based on the thermoacoustic effect, characterized in that, This includes the substrate, graphene dielectric layer, contact metal, and wire dielectric; The substrate is a stretchable structure, obtained by interwoven cotton fabric. The graphene dielectric layer is a three-dimensional structure layer formed by printing graphene and deionized water mixed ink into the substrate. The contact metal is disposed on the substrate and located on both sides of the graphene dielectric layer. One end of the wire medium is disposed in the contact metal, and the other end of the wire medium is connected to the output terminal of the audio player. The resistance and tensile stress of the graphene stretchable sound-generating device satisfy the tensile sound generation negative resistance model, which is as follows: In stage one, the resistance increases, and the sound pressure level decreases. ， In stage two, the resistance decreases and the sound pressure level increases. ， Stage 3: Resistance increases, sound pressure level decreases. ， in, This is the function relating the resistance of the device to the stress in stage one. The initial resistance value of the graphene layer. To describe the modulus of the fabric material deformation in the first stage, This is the stress value. The sound pressure level is the magnitude of the sound pressure level. The thermal conductivity of air, For air heat capacity, The heat capacity of the substrate, For power flux density, The speed of sound in air. The heat capacity of the graphene layer. The thermal conductivity of graphene is... Let R be a quality-related constant, and let R be the corresponding device resistance function in each stage. The length of the device, The resistivity of graphene. The thermal conductivity of graphene, The thickness of the graphene film. The specific heat capacity of graphene. This is a function relating the resistance and stress of devices in stage two or stage three. The device resistance value at the end of phase one. To describe the modulus of fabric deformation in the second stage, This is the stress value at which the resistance begins to decrease as tensile stress increases. This is the stress value at which the resistance begins to rise again when the tensile stress increases. This refers to the relevant quantities of the material and weaving method of the fabric in the X direction.

2. A pre-amplifier driving circuit, characterized in that, Includes an audio modulation module and an operational amplifier module; The input terminal of the audio modulation module is connected to the output terminal of the audio player, and the output terminal of the audio modulation module is connected to the input terminal of the operational amplifier module. It is used to perform pulse density modulation on the voltage of the audio signal output by the audio player to obtain a pulse density modulated signal. The output of the operational amplifier module is connected to the input of the graphene stretchable sound-generating device based on the thermoacoustic effect as described in claim 1, and is used to amplify the voltage of the pulse density modulation signal to obtain a sound signal, so as to drive the graphene stretchable sound-generating device to produce sound.

3. The pre-amplifier driving circuit according to claim 2, characterized in that, It also includes a first DC power supply and a second DC power supply, the first DC power supply being used to power the audio modulation module and the second DC power supply being used to power the operational amplifier module.

4. The pre-amplifier driving circuit according to claim 2, characterized in that, The audio modulation module is model SSM2377.

5. The pre-amplifier driving circuit according to claim 2, characterized in that, The operational amplifier module is model OPA2674.

6. The pre-amplifier driving circuit according to any one of claims 2 to 5, characterized in that, The audio modulation module includes three levels. The three-stage output modulation module, 12dB gain module, and FET voltage drive module; The input terminal of the output modulation module serves as the input terminal of the audio modulation module, and the three-stage... The output terminal of the output modulation module is connected to the input terminal of the 12dB gain module, the output terminal of the 12dB gain module is connected to the input terminal of the FET voltage drive module, and the output terminal of the FET voltage drive module serves as the output terminal of the audio modulation module.

7. The pre-amplifier driving circuit according to any one of claims 2 to 5, characterized in that, The operational amplifier module is a two-stage operational amplifier, with the input terminals of the two-stage operational amplifier serving as the input terminals of the operational amplifier module, and the output terminals of the two-stage operational amplifier serving as the output terminals of the operational amplifier module.

8. A graphene stretchable sound generation system based on thermoacoustic effect, characterized in that, The device includes the graphene stretchable sound-generating device based on thermoacoustic effect as described in claim 1, and the pre-sound driving circuit as described in any one of claims 2 to 7, and further includes an audio player and an audio adapter board; the audio player is used to input audio signals to the pre-sound driving circuit through the audio adapter board.

9. A method for fabricating a graphene stretchable sound-generating device based on the thermoacoustic effect, characterized in that, include: Step 1: On a two-dimensional material printer platform, the substrate is pre-stretched in a regular manner along the horizontal and vertical directions by physical fixation; the substrate is obtained by crisscrossing cotton textile fabric. Step 2: Set the printing parameters on the computer software, mix water-based graphene and deionized water in a 2:3 ratio to obtain printing ink, inject it into the printing needle, start the program and print twice on the sample obtained in Step 1 to obtain a graphene dielectric layer. Step 3: Uniformly arrange the contact metal on both sides of the graphene dielectric layer obtained in Step 2; Step 4: Place one end of the conductor dielectric into the contact metal obtained in Step 3; Step 5: Bake the sample obtained in Step 4 at a temperature of 60℃-70℃ for 4-6 hours to obtain a graphene stretchable sound-generating device based on the thermoacoustic effect. The resistance and tensile stress of the graphene stretchable sound-generating device satisfy the tensile sound generation negative resistance model, which is as follows: In stage one, the resistance increases, and the sound pressure level decreases. ， In stage two, the resistance decreases and the sound pressure level increases. ， Stage 3: Resistance increases, sound pressure level decreases. ， in, This is the function relating the resistance of the device to the stress in stage one. The initial resistance value of the graphene layer. To describe the modulus of the fabric material deformation in the first stage, This is the stress value. The sound pressure level is the magnitude of the sound pressure level. The thermal conductivity of air, For air heat capacity, The heat capacity of the substrate, For power flux density, The speed of sound in air. The heat capacity of the graphene layer. The thermal conductivity of graphene is... Let R be a quality-related constant, and let R be the corresponding device resistance function in each stage. The length of the device, The resistivity of graphene. The thermal conductivity of graphene, The thickness of the graphene film. The specific heat capacity of graphene. This is a function relating the resistance and stress of devices in stage two or stage three. The device resistance value at the end of phase one. To describe the modulus of fabric deformation in the second stage, This is the stress value at which the resistance begins to decrease as tensile stress increases. This is the stress value at which the resistance begins to rise again when the tensile stress increases. This refers to the relevant quantities of the material and weaving method of the fabric in the X direction.

Images