CN108970952B - Tone adjustable nano-scale sound wave generator - Google Patents
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- CN108970952B CN108970952B CN201810753785.8A CN201810753785A CN108970952B CN 108970952 B CN108970952 B CN 108970952B CN 201810753785 A CN201810753785 A CN 201810753785A CN 108970952 B CN108970952 B CN 108970952B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/182—Graphene
- C01B32/194—After-treatment
Abstract
The invention provides a tone-adjustable nanoscale sound wave generator, wherein a graphene film is peeled from an AAO (anaerobic-anoxic-oxic) base film by adopting a water peeling method, and the graphene film is self-supported and separated from the base by freeze drying. The invention avoids two stripping means of reduction stripping and etching stripping, ensures that the stripped graphene film is not damaged at all, and keeps the original form, structure and performance of the graphene film on the AAO base film. Meanwhile, the AAO basement membrane is not damaged at all and can be recycled. The stripping method is suitable for the ultrathin film, and the ultrathin film stripped by the method can realize self-support after freeze drying. After high-temperature treatment, the graphene film has excellent electric heating performance and thermal conductivity, and can effectively cause thermal shock of air at the film. The sound production device has good sound quality and high sound definition. The waveform excited by sound is adjusted by regulating the heat conductivity of the film and designing the middle bearing point of the suspended film, so that the tone is adjusted.
Description
Technical Field
The invention relates to the field of film preparation, in particular to a tone-adjustable nanoscale sound generator.
Background
The graphene film has great electron mobility, extremely high strength, excellent chemical modification property and the like, and is known as a future material. At present, the nano-thickness graphene has great application advantages in the fields of conductive films, photoelectric devices, acoustic detection, gas detection and the like, and is expected to be industrially prepared. The nano-thickness graphene film is divided into CVD graphene and graphene oxide-based nano graphene. The graphene oxide is prepared by oxidizing graphite which accounts for 70% of the world reserves, and is low in price.
The method for stripping the nano graphene film mainly comprises the following steps:
firstly, an etching method, namely preparing a graphene oxide film attached with a substrate by methods of suction filtration, film laying and the like, and etching the substrate by an etchant to obtain an independent self-supporting graphene film with a nano thickness; secondly, peeling the graphene and the substrate by a solid phase transfer method through expansion with heat and contraction with cold of a solid phase substance; thirdly, a solvent precipitation method, namely depositing the graphene oxide film in a coagulating bath by using a wet spinning method, and separating the graphene oxide film from a substrate; fourthly, a chemical reduction transfer method reduces the contact area through suction filtration and chemical reduction, and then surface tension stripping is carried out.
However, all methods either require extra chemical reagents or organic solvents, and cannot achieve a completely green process. In addition, only the solid phase transfer method of the above four methods can prepare graphene films independently self-supporting in the air, but it requires the participation of a chemical agent camphor. Therefore, a green separation and independent self-supporting process is invented, the whole process only needs the participation of water, and a new idea is provided for the preparation of the independent self-supporting graphene.
To date, graphene films have begun to be applied to sound-producing devices, such as laser-produced PI-based graphene films, chemically reduced graphene films. However, the films of the two have inevitable defects, namely large structural defects and low heating speed; secondly, the thickness is very high, the cooling speed is slow, and therefore the sound production definition is poor; thirdly, the film has poor temperature resistance and poor sound adjustment.
Disclosure of Invention
The invention aims to provide a tone-adjustable nanoscale sound generator aiming at the defects of the prior art.
The purpose of the invention is realized by the following technical scheme: a tone-adjustable nanoscale sound wave generator comprises two copper blocks, a sound wave generating film and an electric signal input unit, wherein two ends of the sound wave generating film are lapped on the surfaces of the copper blocks, and the two copper blocks are respectively connected with the positive electrode and the negative electrode of the electric signal input unit; the sound wave generating film is a graphene film and is prepared by the following method:
(1) stripping the graphene film from the AAO base film, specifically: placing the AAO base film with the graphene film attached to the surface on the water surface with the surface of the graphene film facing upwards; pressing the AAO base film to enable the AAO base film to sink, and enabling the graphene film to float on the water surface;
(2) fishing up the graphene film floating on the water surface from bottom to top by utilizing a substrate, so that the graphene film is laid on the surface of the substrate, and a layer of aqueous medium is arranged between the graphene film and the substrate;
(3) freeze-drying the substrate with the graphene film on the surface, wherein the graphene film is self-supported and separated from the substrate;
(4) and (2) placing the graphene film in a high-temperature furnace, heating to 1500 ℃ at 5-20 ℃ per minute, and then heating to 2000 ℃ at 2-5 ℃ per minute to obtain the graphene film capable of being used for the sound wave generator.
Further, in step 1, the pressing position is an edge of the AAO base film.
Further, the graphene film has a thickness of 4 nm.
Further, the graphene film is a graphene oxide film or a reduced graphene oxide film.
Further, the porosity of the surface of the AAO base film is not less than 40%.
Further, the substrate in step 2 is a hydrophobic substrate.
Further, the upper surface of the substrate in step 2 has a recessed region.
Further, both ends of the sound wave generating film are lapped on the upper surface of the copper block by the following method: spraying ethanol on the upper surface of the copper block, attaching the end part of the sound wave generating film to the surface of the liquid, and evaporating the ethanol.
Furthermore, two ends of the sound wave generating film are further fixed on the surface of the copper block through packaging materials, and the sound wave generating film is in direct contact with the surface of the copper block.
The invention has the beneficial effects that: the invention avoids two stripping means of reduction stripping and etching stripping, ensures that the stripped graphene film is not damaged at all, and keeps the original form, structure and performance of the graphene film on the AAO base film. Meanwhile, the AAO basement membrane is not damaged at all and can be recycled. The stripping method is suitable for the ultrathin film, and the ultrathin film stripped by the method can realize self-support after freeze drying. Through sintering treatment, the film structure is perfect, the structure and stacking defects are few, the conductivity is high, and the temperature rise speed is high; the thickness of the film can be controlled below 60nm, the heat conductivity is high, and the sound production voltage is low; the temperature rise and fall speed is fast, and the film is determined to have excellent tone quality and high sound definition. Through structural design, the film can adjust the waveform excited by sound through regulating the thermal conductivity of the film and designing the middle bearing point of the suspended film, and then the tone is adjusted.
Drawings
Fig. 1 is a schematic flow chart of peeling a graphene film from an AAO base film;
FIG. 2 is a graph of the experimental procedure for peeling off a graphene film from an AAO base film of example 1;
fig. 3 is a photograph of a self-supporting graphene film prepared in example 1;
FIG. 4 is an atomic force microscope image of a self-supporting graphene film prepared in example 1;
fig. 5 is a schematic view of a substrate of example 2, in which 1 is a substrate with a central depression, 2 is a graphene film, and 3 is water.
Fig. 6 a photograph of a self-supporting graphene film prepared in example 2;
FIG. 7 is an atomic force microscope image of a self-supporting graphene film prepared in example 2;
fig. 8 is a graph showing an experimental process of peeling a graphene film from an MCE base film of comparative example 1.
Fig. 9 is a temperature rise and decrease curve of the graphene film obtained in example 1;
fig. 10 is a temperature curve of the graphene film along the direction of the straight line where the two electrodes are located at the time T ═ 1 s.
Fig. 11 is a temperature profile of the graphene film having 3 heat conduction points in example 2 at a time T ═ 1 s.
Detailed Description
Example 1
(1) By controlling the concentration of the graphene solution, carrying out suction filtration on an AAO (anodic aluminum oxide) base film by a suction filtration method to obtain an ultrathin reduced graphene oxide film;
(2) stripping the graphene film from the AAO base film, specifically: placing an AAO base film (with a porosity of 40%) with a reduced graphene oxide film attached to the surface on a water surface with the graphene film facing upward, as shown in fig. 1a and 2 a; pressing the edge of the AAO base film as in fig. 2b, the AAO base film starts to sink as in fig. 2c, and finally, the AAO base film sinks to the bottom of the cup, and the graphene film floats on the water surface (inside the dashed circle) as in fig. 1b and 2 d.
(3) A glass substrate with a surface printed with Zhejiang university is utilized to drag up the graphene film floating on the water surface from bottom to top, so that the graphene film is paved on the surface of the substrate, and a layer of water medium is arranged between the graphene film and the substrate.
(4) The substrate with the graphene film loaded on the surface is subjected to freeze drying, and the graphene film is self-supported and separated from the substrate as shown in fig. 3. The thickness was 4nm as shown in FIG. 4, as measured by atomic force microscopy.
(5) Placing the graphene film in a high-temperature furnace, and heating to 1500 ℃ at 5 ℃ per minute; raising the temperature to 2000 ℃ per minute at the temperature of 2 ℃ to obtain the nano-scale sound wave generation film.
Spraying ethanol on the upper surface of the copper block, attaching the end of the sound wave generating film to the surface of the liquid, and evaporating ethanol to 2 × 2cm2The two ends of the sound wave generating film are lapped on the surfaces of the copper blocks, the two copper blocks are respectively connected with the positive electrode and the negative electrode of a 10V power supply, the temperature change of the middle position of the graphene film is measured by using a temperature control sensor, the stable temperature of the graphene film is up to 612 ℃ in 0.5 second under the direct current voltage of 10V in the atmospheric environment, and after the graphene film is powered off, the temperature of the graphene film is reduced to be close to the room temperature within 0.7 second due to the excellent thermal conductivity of the graphene film, as shown in figure 9. At the time T ═ 1s, an infrared detector is used to obtain a temperature distribution map of the surface of the thin film, and the graphene film is high in the middle and low at both ends along the direction of the straight line where the two electrodes are located, as shown in fig. 10. The waveforms of the film at different temperatures represent the mode of vibration of the film to air, and cause air vibration in the process of temperature rise and drop and form sound waves corresponding to the waveforms. Therefore, by adjusting the thermal conductivity of graphene (the higher the thermal conductivity, the better the uniformity of heat, the wave shape)The flatter) the waveform of the sound wave can be changed, so that different timbres are obtained.
Spraying ethanol on the upper surface of the copper block, attaching the end part of the sound wave generating film to the liquid surface, evaporating the ethanol to enable the two ends of the sound wave generating film to be lapped on the surface of the copper block, and respectively connecting the two copper blocks with the positive electrode and the negative electrode of the electric signal input unit to form the tone-adjustable nanoscale sound wave generator. Because the film has high electrical conductivity, the film can release heat and raise temperature violently under the condition of external voltage, the external voltage is removed, the heat dissipation speed of the film is extremely high due to good thermal conductivity and thin thickness, and the film can quickly raise and lower the temperature under the combined action, so that the thermal shock of the air at the film is caused, and the film can sound. Therefore, through the auxiliary loading of the direct current voltage of 10V and additionally loading a specified input audio signal, the voltage and the change frequency of the whole input are adjusted, and the determined air thermal vibration amplitude, namely the pitch, can be obtained; the thermal vibration frequency of the air can be adjusted by adjusting the frequency of the input signal, so that the frequency of sounding is changed to send different sounds; and the tone of the sound generator is adjustable.
Example 2
(1) The method comprises the steps of (1) obtaining an ultrathin graphene oxide film by suction filtration on an AAO (alkaline-earth oxide) base film through a suction filtration method by controlling the concentration of a graphene solution;
(2) stripping the graphene film from the AAO base film, specifically: placing the AAO base film (with the porosity of 60%) with the graphene oxide film attached to the surface on the water surface with the surface of the graphene film facing upwards, pressing the edge of the AAO base film to enable the AAO base film to start sinking, finally enabling the AAO base film to sink to the cup bottom, enabling the graphene film to float on the water surface, and successfully stripping the graphene film.
(3) A hydrophilic silicon substrate with a surface printed with Zhejiang university (silicon surface is subjected to hydrophilic treatment, and the center is sunken as shown in figure 5) is used for scooping up the graphene film floating on the water surface from bottom to top, so that the graphene film is paved at the center of the substrate, and the graphene film and the sunken center are provided with an aqueous medium.
(4) The substrate with the graphene film loaded on the surface is subjected to freeze drying, and the graphene film is self-supported, as shown in fig. 6, and is separated from the substrate. The thickness was 14nm as shown in FIG. 7, as measured by atomic force microscopy.
(5) Placing the graphene film in a high-temperature furnace, and heating to 1500 ℃ at 20 ℃ per minute; raising the temperature to 2000 ℃ per minute at 5 ℃, and preserving the heat for 1h to obtain the nanoscale sound wave generation film.
Spraying ethanol on the upper surface of the copper block, attaching the end of the sound wave generating film to the surface of the liquid, and evaporating ethanol to 2 × 2cm2The two ends of the sound wave generation film are lapped on the surfaces of the copper blocks, the two copper blocks are respectively connected with the positive electrode and the negative electrode of a 10V power supply, the temperature change in the middle of the graphene film is measured by using a temperature control sensor, the stable temperature of the graphene film is 598 ℃ only needing 0.5 second under the direct current voltage of 10V in the atmospheric environment, and after the graphene film is powered off, the temperature of the graphene film is reduced to be close to the room temperature within 0.7 second due to the excellent thermal conductivity of the graphene film. And (3) acquiring a film surface temperature distribution diagram by using an infrared detector at the moment T is 1s, wherein the graphene film is high in the middle and low at two ends along the linear direction of the two electrodes.
A silicon block is arranged in the middle between the two copper blocks, and the middle of the sound wave generating film is in direct contact with the surface of the silicon block. According to the method, 10V direct current voltage is input into the two copper blocks, and for the time T being 1s, a temperature distribution graph of the surface of the film is obtained by using an infrared detector, wherein the graphene film changes along the direction of a straight line where the two electrodes are located, and the temperature curve is shown in fig. 11. Therefore, different timbres can be obtained by changing the temperature change curve by linearly increasing the heat deriving point, thereby changing the waveform of the sound wave.
Comparative example 1
An MCE base film (porosity: 60%) with a reduced graphene oxide film attached to the surface thereof was placed on a water surface with the side of the graphene film facing up, and as shown in fig. 8a, the MCE base film did not sink when the edge of the MCE base film was pressed, and as shown in fig. 8b, the graphene film failed to be peeled off.
The filtration method is the most uniform method for preparing graphene films, and can control the thickness of a graphene film by regulating and controlling the concentration under a certain amount of filtration liquid, the thickness can be the lowest graphene, the newly added graphene gradually fills the gap of the first graphene layer under the action of pressure along with the increase of the concentration of the graphene, so that the first graphene layer is gradually and completely filled, and then the first graphene layer is developed into a second graphene layer, and the steps are continuously repeated, so that the graphene nano film with the thickness of 2 to ten thousand graphene layers can be prepared. Therefore, the graphene film with the thickness of 4nm can be obtained by simple experimental parameter adjustment by the skilled person.
Claims (9)
1. A tone-adjustable nanoscale sound wave generator is characterized by comprising two copper blocks, a sound wave generating film and an electric signal input unit, wherein two ends of the sound wave generating film are lapped on the surfaces of the copper blocks, and the two copper blocks are respectively connected with the positive electrode and the negative electrode of the electric signal input unit; the sound wave generating film is a graphene film and is prepared by the following method:
(1) stripping the graphene film from the AAO base film, specifically: placing the AAO base film with the graphene film attached to the surface on the water surface with the surface of the graphene film facing upwards; pressing the AAO base film to enable the AAO base film to sink, and enabling the graphene film to float on the water surface;
(2) fishing up the graphene film floating on the water surface from bottom to top by utilizing a substrate, so that the graphene film is laid on the surface of the substrate, and a layer of aqueous medium is arranged between the graphene film and the substrate;
(3) freeze-drying the substrate with the graphene film on the surface, wherein the graphene film is self-supported and separated from the substrate;
(4) and (2) placing the graphene film in a high-temperature furnace, heating to 1500 ℃ at 5-20 ℃ per minute, and then heating to 2000 ℃ at 2-5 ℃ per minute to obtain the graphene film capable of being used for the sound wave generator.
2. The timbre-tunable nanoscale sound-wave generator of claim 1, wherein in step (1), the pressing position is an edge of an AAO base film.
3. The timbre-tunable nanoscale acoustic-wave generator of claim 1, wherein the graphene film is 4nm thick.
4. The timbre-tunable nanoscale acoustic-wave generator of claim 1, wherein the graphene film is a graphene oxide film or a reduced graphene oxide film.
5. The timbre-tunable nanoscale sound-wave generator of claim 1, wherein the surface of the AAO base film has a porosity of not less than 40%.
6. The timbre-tunable nanoscale sound-wave generator as claimed in claim 1, wherein the substrate in step (2) is a hydrophobic substrate.
7. The timbre-tunable nanoscale sound-wave generator of claim 6, wherein the upper surface of the substrate in step (2) has a recessed region.
8. The timbre-tunable nanoscale sound wave generator as claimed in claim 1, wherein both ends of the sound wave generating film are bonded to the upper surface of the copper block by: spraying ethanol on the upper surface of the copper block, attaching the end part of the sound wave generating film to the surface of the liquid, and evaporating the ethanol.
9. The timbre-adjustable nanoscale sound wave generator as claimed in claim 1, wherein both ends of the sound wave generating film are further fixed on the surface of the copper block through a packaging material, and the sound wave generating film is in direct contact with the surface of the copper block.
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| CN101846653B (en) * | 2010-04-30 | 2011-09-14 | 湖北大学 | Piezoelectric film bulk acoustic wave sensor with polygonal electrodes |
| CN102307325B (en) * | 2011-07-21 | 2014-04-16 | 清华大学 | Thermophone device |
| CN103365004B (en) * | 2013-07-26 | 2016-04-13 | 深圳市华星光电技术有限公司 | Transparency conducting layer, the CF substrate with this transparency conducting layer and preparation method thereof |
| CN104448360B (en) * | 2013-09-22 | 2018-04-27 | 福建省辉锐材料科技有限公司 | A kind of preparation method of piezoelectricity polyvinylidene difluoride film |
| CN107409258B (en) * | 2014-10-06 | 2020-03-17 | 奥拉石墨烯声学股份有限公司 | Method for forming acoustic transducer based on graphene oxide |
| CN105329884B (en) * | 2015-11-24 | 2017-05-24 | 东南大学 | Method for rapidly peeling and transferring graphene oxide leaching film to substrate |
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| CN107915220B (en) * | 2017-11-17 | 2021-02-09 | 合肥国轩高科动力能源有限公司 | Method for transferring graphene patterned film by gas-liquid interface separation method |
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