CN108970952B - Tone adjustable nano-scale sound wave generator - Google Patents

Abstract

The invention provides a nano-scale sound wave generator with adjustable tone. The graphene film is peeled off from the AAO base film by a water stripping method, and the graphene film is self-supporting and separated from the base through freeze drying. The invention avoids the two stripping methods of reduction stripping and etching stripping, ensures that the graphene film obtained by stripping is not damaged in any way, and maintains its original shape, structure and performance on the AAO base film. At the same time, there is no damage to the AAO basement membrane, and it can be reused. This peeling method is suitable for ultra-thin films, and the ultra-thin films peeled off by the above method can be self-supporting after freeze-drying. After high temperature treatment, the graphene film has excellent electrical and thermal properties and thermal conductivity, which can effectively induce thermal vibration of the air at the film. The sound-emitting device has good sound quality and high sound clarity. By adjusting the thermal conductivity of the film and designing the intermediate connection point of the suspended film, the waveform excited by the sound can be adjusted, and then the timbre can be adjusted.

Description

A nanoscale sound wave generator with adjustable timbre

technical field

The invention relates to the field of membrane preparation, in particular to a nanoscale sound wave generator with adjustable timbre.

Background technique

Graphene film has great electron mobility, extremely high strength, excellent chemical modification, etc., and is known as the material of the future. At present, nano-thick graphene has shown great application advantages in conductive thin films, optoelectronic devices, acoustic wave detection, gas detection and other fields, and is expected to be industrially prepared. Among them, nano-thick graphene films are divided into two types: CVD graphene and graphene oxide-based nano-graphene. Graphene oxide is produced by oxidation of graphite, which accounts for 70% of the world's reserves, and is inexpensive.

The peeling methods of nanographene films mainly include the following:

First, the etching method prepares a graphene oxide film with a substrate by suction filtration, film laying and other methods, and etches the substrate through an etchant to obtain an independent and self-supporting nanometer-thick graphene film; second, solid phase Transfer method, exfoliating graphene and substrate through thermal expansion and contraction of solid phase substance; third, solvent precipitation method, using wet spinning method, the graphene oxide film is deposited in a coagulation bath and separated from the substrate; Fourth, chemical reduction transfer method, through suction filtration, chemical reduction reduces the contact area, and then the surface tension peels off.

But all the methods either require redundant chemical reagents or organic solvents, and cannot achieve a complete green process. In addition, among the above four methods, only the solid-phase transfer method can prepare the independent self-supporting graphene film in air, but it requires the participation of the chemical reagent camphor. To this end, we invented a green separation and independent self-supporting process, and the whole process only requires the participation of water, which provides a new idea for the preparation of independent self-supporting graphene.

So far, graphene films have been used in sound-emitting devices, such as PI-based graphene films prepared by laser and chemically reduced graphene films. However, the above two films have unavoidable defects. First, the structural defects are large and the heating rate is slow; second, the thickness is high and the cooling rate is slow, so the clarity of the sound is poor; third, the temperature resistance of the film is relatively high. Poor, poor sound adjustment.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a nano-scale sound wave generator with adjustable timbre in view of the deficiencies of the prior art.

The object of the present invention is achieved through the following technical solutions: a nano-scale sound wave generator with adjustable timbre, comprising two copper blocks, a sound wave generating film, and an electrical signal input unit, the two ends of the sound wave generating film are overlapped on the copper On the surface of the block, two copper blocks are respectively connected with the positive and negative electrodes of the electrical signal input unit; the acoustic wave generating film is a graphene film, which is prepared by the following method:

(1) peeling off the graphene film from the AAO base film, specifically: the AAO base film with the graphene film attached on the surface is placed on the water surface with the face where the graphene film is located facing up; pressing the AAO base film, so that The AAO basement membrane sinks, and the graphene membrane floats on the water surface;

(2) utilize a substrate to pick up the graphene film floating on the water surface from bottom to top, so that the graphene film is spread on the surface of the substrate, and there is a layer of water medium between the graphene film and the substrate;

(3) the substrate carrying the graphene film on the surface is freeze-dried, and the graphene film is self-supporting and separated from the substrate;

(4) The graphene film is placed in a high temperature furnace, heated to 1500 degrees Celsius at 5-20 degrees Celsius per minute, and then heated to 2000 degrees Celsius at 2-5 degrees Celsius per minute to obtain graphene films that can be used in acoustic wave generators.

Further, in the step 1, the pressing position is the edge of the AAO basement membrane.

Further, the thickness of the graphene film is 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 described in step 2 is a hydrophobic substrate.

Further, the upper surface of the substrate described in step 2 has a concave area.

Further, the two ends of the sound wave generating film are overlapped 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 of the sound wave generating film to the liquid surface, and evaporating the ethanol.

Further, both ends of the sound wave generating film are further fixed on the surface of the copper block through the packaging material, and the sound wave generating film is in direct contact with the surface of the copper block.

The beneficial effects of the present invention are as follows: the present invention avoids the two peeling means of reduction peeling and etching peeling, ensures that the graphene film obtained by peeling is not damaged in any way, and maintains its original form, structure and performance on the AAO base film . At the same time, there is no damage to the AAO basement membrane, and it can be reused. This peeling method is suitable for ultra-thin films, and the ultra-thin films peeled off by the above method can be self-supporting after freeze-drying. Through the sintering treatment, the film has a perfect structure, less structural and stacking defects, high electrical conductivity, and fast heating rate; and the film thickness can be controlled below 60 nm, with high thermal conductivity and low sounding voltage; fast heating and cooling rate determines this film. It has excellent sound quality and high sound clarity. Through structural design, the film can adjust the waveform of sound excitation by adjusting the thermal conductivity of the film and designing the intermediate connection point of the suspended film, thereby adjusting the tone.

Description of drawings

Fig. 1 is the schematic flow chart of AAO base film peeling graphene film;

Fig. 2 is the experimental process diagram of embodiment 1AAO base film peeling graphene film;

Fig. 3 is the photo of the self-supporting graphene film that embodiment 1 prepares;

Fig. 4 is the atomic force microscope image of the self-supporting graphene film prepared by embodiment 1;

5 is a schematic diagram of the substrate of Example 2, in the figure, 1 is a substrate with a concave center, 2 is a graphene film, and 3 is water.

The photo of the self-supporting graphene film that Fig. 6 embodiment 2 prepares;

Fig. 7 is the atomic force microscope image of the self-supporting graphene film prepared by embodiment 2;

FIG. 8 is a diagram showing the experimental process of peeling off the graphene film from the MCE base film of Comparative Example 1. FIG.

Fig. 9 is the heating and cooling curve of the graphene film obtained in Example 1;

FIG. 10 is the temperature curve of the graphene film along the straight line where the two electrodes are located at the time of T=1s.

FIG. 11 is the temperature curve of the graphene film with three heat extraction points in Example 2 at the time of T=1s.

Detailed ways

Example 1

(1) by controlling the concentration of the graphene solution, an ultrathin reduced graphene oxide membrane is obtained by suction filtration on the AAO base membrane;

(2) Peeling the graphene film from the AAO base film, specifically: attaching the AAO base film (porosity of 40%) with the reduced graphene oxide film on the surface, with the graphene film facing up, and placing On the water surface, as shown in Figures 1a and 2a; press the edge of the AAO basement membrane, as shown in Figure 2b, the AAO basement membrane begins to sink, as shown in Figure 2c, and finally, the AAO basement membrane sinks to the bottom of the cup, and the graphene membrane floats on the water surface (dotted circle). inside), as shown in Figures 1b and 2d.

(3) Use a glass substrate with "Zhejiang University" printed on the surface to lift up the graphene film floating on the water surface, so that the graphene film is spread on the surface of the substrate, and there is a gap between the graphene film and the substrate. Layer water medium.

(4) freeze-dry the substrate with the graphene film on the surface, and the graphene film is self-supporting, as shown in FIG. 3 , and separated from the substrate. Tested by atomic force microscope, its thickness is 4 nm, as shown in Figure 4.

(5) The graphene film is placed in a high temperature furnace, and the temperature is raised to 1500 degrees Celsius per minute at 5 degrees Celsius; and the temperature is raised to 2000 degrees Celsius per minute at 2 degrees Celsius to obtain a nano-scale sound wave generating film.

Spray ethanol on the upper surface of the copper block, stick the end of the sound wave generating film on the surface of the liquid, evaporate the ethanol, so that the two ends of the 2×2cm ² sound wave generating film overlap the surface of the copper block, and the two copper blocks are respectively connected to a 10V power supply The positive and negative electrodes are connected to each other, and a temperature control sensor is used to measure the temperature change in the middle of the graphene film. This graphene film only needs 0.5 seconds to reach a stable temperature of 612°C under the atmospheric environment and a DC voltage of 10V, while After power-off, due to the excellent thermal conductivity of the graphene film, the temperature of the film dropped to near room temperature within 0.7 seconds, as shown in Figure 9. At the time of T=1s, an infrared detector is used to obtain the temperature distribution map of the film surface. The graphene film is along the straight line direction of the two electrodes, the middle is high, and the two ends are bottom, as shown in Figure 10. The waveforms of the film at different temperatures represent the way that the film vibrates to the air, which causes the air to vibrate during the heating and cooling process, and forms sound waves with corresponding waveforms. Therefore, by adjusting the thermal conductivity of graphene (the higher the thermal conductivity, the better the uniformity of heat and the flatter the waveform), the waveform of the sound wave can be changed to obtain different timbres.

Spray ethanol on the upper surface of the copper block, attach the end of the sound wave generating film to the liquid surface, evaporate the ethanol, so that the two ends of the sound wave generating film overlap the surface of the copper block, and the two copper blocks are respectively connected to the positive side of the electrical signal input unit The negative poles are connected to form the nanoscale sound wave generator with adjustable timbre of the present invention. Due to the high electrical conductivity of the film, it will exothermic and heat up violently under the condition of applied voltage. When the applied voltage is withdrawn, the film has a very high heat dissipation rate due to its good thermal conductivity and thin thickness. The two work together to make the film can The temperature rises and falls rapidly, which causes thermal vibrations of the air at the film, thereby producing sound. Therefore, through the auxiliary loading of 10V DC voltage, and additionally loading the specified input audio signal, and adjusting the overall input voltage and changing frequency, the determined air thermal vibration amplitude, that is, the pitch, can be obtained; the air can be adjusted by adjusting the input signal frequency. The frequency of thermal vibration and then the frequency of sound is changed, and different sounds are produced; and the sound wave generator has an adjustable timbre.

Example 2

(1) by controlling the concentration of the graphene solution, an ultrathin graphene oxide film is obtained by suction filtration on the AAO base membrane by suction filtration;

(2) Peel off the graphene film from the AAO base film, specifically: place the AAO base film (porosity 60%) with the graphene oxide film attached to the surface, with the graphene film facing up, and place it on the AAO base film. On the water surface, press the edge of the AAO basement membrane, the AAO basement membrane begins to sink, and finally, the AAO basement membrane sinks to the bottom of the cup, the graphene membrane floats on the water surface, and the graphene membrane is successfully peeled off.

(3) Using a hydrophilic silicon substrate with "Zhejiang University" printed on its surface (the silicon surface is hydrophilic, the center is concave, as shown in Figure 5), the graphene film floating on the water surface is lifted from the bottom to the top, so that the graphite The graphene film is tiled on the center of the substrate, and the center of the graphene film and the depression has an aqueous medium.

(4) freeze-dry the substrate with the graphene film on the surface, and the graphene film is self-supporting, as shown in FIG. 6 , and separated from the substrate. Tested by atomic force microscope, its thickness is 14 nm, as shown in Figure 7.

(5) The graphene film is placed in a high-temperature furnace, heated to 1500 degrees Celsius per minute at 20 degrees Celsius; heated to 2000 degrees Celsius per minute at 5 degrees Celsius, and kept for 1 hour to obtain a nanoscale acoustic wave generating film.

Spray ethanol on the upper surface of the copper block, stick the end of the sound wave generating film on the surface of the liquid, evaporate the ethanol, so that the two ends of the 2×2cm ² sound wave generating film overlap the surface of the copper block, and the two copper blocks are respectively connected to a 10V power supply The positive and negative electrodes are connected to each other, and a temperature control sensor is used to measure the temperature change in the middle of the graphene film. This graphene film only needs 0.5 seconds to reach a stable temperature of 598 ° C under the atmospheric environment and a DC voltage of 10 V, while the off After electrification, the temperature of the graphene film dropped to near room temperature within 0.7 seconds due to the excellent thermal conductivity of the graphene film. At the time of T=1s, an infrared detector is used to obtain the temperature distribution map of the film surface. The graphene film is along the straight line direction of the two electrodes, the middle is high, and the two ends are bottom.

A silicon block is placed in the middle position between the two copper blocks, and the middle position of the sound wave generating film is in direct contact with the surface of the silicon block. According to the above method, input a DC voltage of 10V to the two copper blocks, and at the time of T=1s, use an infrared detector to obtain the temperature distribution map of the film surface. The graphene film changes along the straight line direction of the two electrodes, as shown in the figure 11 shown. Therefore, by linearly increasing the heat export point, changing the temperature change curve, and thus changing the sound wave waveform, different timbres can be obtained.

Comparative Example 1

Place the MCE base film (porosity 60%) with the reduced graphene oxide film on the surface, with the graphene film facing up, and place it on the water surface, as shown in Figure 8a, press the edge of the MCE base film, the MCE base The film did not sink, and as shown in Figure 8b, the graphene film failed to peel off.

It should be noted that the suction filtration method is currently recognized as the most uniform method for preparing graphene membranes. Under a certain amount of suction filtrate, the concentration can be adjusted to control the thickness of the graphene membrane, and the minimum thickness can be a layer of graphene. , With the increase of graphene concentration, under the action of pressure, the newly added graphene gradually fills the gap of the first layer of graphene, so that the first layer of graphene is gradually completely filled, and then develops into the second layer, and the above is repeated continuously. step, a graphene nanofilm with a thickness ranging from 2 to tens of thousands of graphene layers can be prepared. Therefore, those skilled in the art can obtain a graphene film with a thickness of 4 nm by simply adjusting the experimental parameters.

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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