CN116317671A - Acoustic wave friction nano generator based on bionic cochlea - Google Patents

Abstract

The invention discloses a bionic cochlea-based acoustic wave friction nano generator, which comprises a spiral tube cavity, a cylindrical cavity and an acoustic wave friction nano generator; the spiral tube cavity and the cylindrical cavity form a bionic cochlea structure. The invention utilizes the sound pressure amplifying structure imitating the human cochlea and the sound wave friction nano generator as the generating unit to collect sound wave energy, has the advantages of generating larger electric energy at lower frequency, reaching the output power of up to 324 microwatts at the resonance frequency of 210Hz, and greatly improving the conversion efficiency of the electric energy. The invention adopts the equiangular spiral which is a tapered spiral from outside to inside, has more obvious effect of amplifying sound pressure, has compact structure and is convenient for array installation and deployment. The invention adopts the acoustic friction nano generator, and the material has the characteristics of low price and light weight, and has great application potential in the aspects of sensing and energy supply of a wireless sensor network and the Internet of things.

Description

Acoustic wave friction nano generator based on bionic cochlea

Technical Field

The invention relates to an acoustic-electric conversion technology, in particular to an acoustic friction nano generator based on a bionic cochlea.

Background

Acoustic waves are clean energy sources with wide distribution and abundant reserves in nature, and most of the energy is wasted due to low energy density and lack of effective energy collection technology. If widely distributed acoustic wave energy is effectively utilized, the acoustic wave energy is converted into electric energy and stored for use, an important thought is provided for supplying power to the products of the Internet of things, and the requirement of a sensing device which is widely applied in the fields of infrastructure, environment monitoring and the like on energy sources can be met, so that the application of a self-energy supply system in human life is forcefully promoted, and great convenience is brought to the life of people.

The energy collector obtains input energy from various sources (machine, human or natural) at a frequency in the range of 1Hz to 10kHz. And then the circuit management module is utilized to rectify the electric signal, match the optimal impedance and finally be used for supplying energy to the sensor, storing electric energy or supplying power in a small size. The energy collector typically includes an acoustic resonance device, a vibrating membrane, and a power generating material. An energy harvester performs the energy conversion from sonic vibration to electrical energy output, which typically requires time to accumulate enough useful energy to operate the electronic system. The modes commonly used for acoustic-electric conversion include piezoelectric mode and electromagnetic mode, the piezoelectric materials commonly used in the piezoelectric mode have higher sensitivity, the output energy density is lower, and the common application is limited; electromagnetic acoustic-electric converters are generally difficult to cut magnetic induction lines, have the characteristic of high frequency, and have low electric energy output efficiency. The acoustic friction nano generator is widely applied to collecting low-frequency mechanical energy in life, such as wave energy, wind energy and the like, and has the advantages of low cost, light weight, easiness in manufacturing and the like. The sound wave can provide higher driving frequency, and is very suitable for being collected and utilized by rubbing the nano generator through the sound wave.

Currently, acoustic resonance devices (including helmholtz, half wave, quarter wave tube) are commonly utilized in combination with acoustic friction nano generators for collecting acoustic wave energy. If the Archimedes spiral sound wave power generation device based on the piezoelectric effect is provided, the device can collect sound wave energy in a lower frequency band, supply energy for low-power consumption electronic components, and achieve resonance at 260Hz, but the maximum output power is only 8.2 microwatts, and the power generation efficiency still needs to be further improved to realize better application value.

Disclosure of Invention

In order to solve the problems in the prior art, the invention designs the bionic cochlea-based acoustic friction nano-generator capable of improving the power generation efficiency.

In order to achieve the above object, the technical scheme of the present invention is as follows: a bionic cochlea-based acoustic wave friction nano generator comprises a spiral tube cavity, a cylindrical cavity and an acoustic wave friction nano generator;

the spiral pipe cavity comprises a spiral pipe and a bottom plate, and the spiral pipe is an equiangular spiral pipe; the bottom plate is fixed at the lower end of the spiral pipe;

the cylindrical cavity is fixed at the upper end of the spiral pipe; the upper side of the cylindrical cavity is provided with a cylindrical groove, the bottom of the cylindrical groove is provided with a round hole, and the center of the round hole is positioned on the central axis of the base circle of the equiangular spiral pipe;

the acoustic friction nano generator comprises an aluminum film, an electrode and an FEP film; the FEP film is a fluorinated ethylene propylene copolymer film; the aluminum film is stuck to the periphery of the opening of the cylindrical groove, and a plurality of sound holes are formed in the aluminum film; the FEP film is covered on the aluminum film, and the periphery of the FEP film is adhered and fixed with the periphery of the aluminum film; the electrode is a conductive ink printing electrode and is printed on the upper surface of the FEP film;

the upper end and the lower end of the spiral pipe form an equiangular spiral resonant cavity with a cavity between the cylindrical cavity and the bottom plate respectively; a cylindrical resonant cavity is formed between the aluminum film and the cylindrical groove;

the spiral tube cavity and the cylindrical cavity form a bionic cochlea structure.

Furthermore, the spiral tube and the bottom plate are integrated pieces printed in a 3D mode, and a closed space is formed in the working process of the equiangular spiral resonant cavity.

Further, the lower surface of the cylindrical cavity is the same as the shape and the size of the bottom plate.

Further, the spiral tube and the cylindrical cavity are fixed by hot melt adhesive.

Furthermore, round through holes with the diameter of 1.5mm and the longitudinal and transverse spacing of 1mm are uniformly distributed on the surface of the aluminum film.

Further, the projection line of the spiral pipe on the horizontal plane is an equiangular spiral curve and is expressed by the following formula:

x＝a*cos(t)*exp(b*t)

y＝a*sin(t)*exp(b*t)

wherein a is the initial radius of a base circle, b is tan (theta), theta is the diffusion angle of equiangular spiral, which is complementary to the equiangular phi, t is the angle parameter, the unit is radian, and the initial value is 0.

The working principle of the invention is as follows:

the equiangular spiral resonant cavity is similar to a spiral external auditory canal, sound waves enter from a rectangular opening of the equiangular spiral resonant cavity, incident sound waves are transmitted through the equiangular spiral resonant cavity, the sound pressure level gradually increases along with the decrease of an outer arm of the equiangular spiral resonant cavity, the maximum sound pressure value in the equiangular spiral resonant cavity occurs at the center of the equiangular spiral resonant cavity, and the amplified sound waves enter the cylindrical resonant cavity through a round hole of the cylindrical cavity and are equivalent to the sound waves entering an inner ear through an external auditory canal; by utilizing the principle of back and forth vibration of sound waves, the transverse fibers of the cochlea base membrane of the inner ear can react like a string to be sensitive to sound, and the sound-electricity conversion is realized by continuously contacting and separating the aluminum membrane and the FEP membrane of the sound wave friction nano generator due to the excitation of the sound waves.

The acoustic friction nano generator is used as a power generation unit and consists of an FEP film, conductive ink and an aluminum film, wherein the conductive ink is printed on the FEP film to serve as a carbon electrode, and the aluminum film serves as an aluminum electrode. When the acoustic friction nano generator works, the FEP film and the aluminum film are initially in a separated state, and electrons in the aluminum are free electrons. The FEP film is forced to vibrate under progressively increasing acoustic pressure drive. When the FEP film is in contact with the aluminum film, the inner surfaces of the FEP film and the aluminum film develop equal and opposite electrostatic charges. As the film tension and acoustic pressure change, the FEP film tends to leave the aluminum film, and interfacial separation of positive and negative charges results in an induced potential difference between the two electrodes. This difference may push free electrons on the carbon electrode to flow toward the aluminum electrode. During this process, the potential tends to equilibrate, creating a positive charge on the carbon electrode. The contact and separation action between the aluminum film and the FEP film further generates potential difference between the surface of the aluminum film and the surface of the FEP film, and alternating current is generated through electrostatic induction, so that the transferred mechanical strain energy is converted into electric energy, and the electromechanical energy conversion is realized.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention utilizes the sound pressure amplifying structure imitating the human cochlea and the sound wave friction nano generator as the generating unit to collect sound wave energy, has the advantages of generating larger electric energy at lower frequency, reaching the output power of up to 324 microwatts at the resonance frequency of 210Hz, and greatly improving the conversion efficiency of the electric energy.

2. The invention adopts the equiangular spiral which is a tapered spiral from outside to inside, has more obvious effect of amplifying sound pressure, has compact structure and is convenient for array installation and deployment.

3. The invention adopts the acoustic friction nano generator, and the material has the characteristics of low price and light weight; the equiangular spiral tube is printed by a 3D printer, the overall cost of the device is low, the sound-electricity conversion efficiency is high under low frequency, the commercialized mass production and the application are facilitated, and the device has great application potential in the aspects of sensing and energy supply of a wireless sensor network and the Internet of things.

Drawings

Fig. 1 is a schematic overall structural view of the present invention.

Fig. 2 is an exploded structural view of fig. 1.

Fig. 3 is a geometric schematic of the spiral variation.

FIG. 4 is a schematic view of the coil and base plate structure.

FIG. 5 is a schematic diagram of open circuit voltage output at frequencies between 140Hz and 280 Hz.

Fig. 6 is a graph of the maximum open circuit voltage output of the present invention.

Fig. 7 is a graph of the maximum short circuit current output of the present invention.

Fig. 8 is a graph of the maximum transferred charge output of the present invention.

In the figure: 1. the bottom plate, 2, spiral pipe, 3, round hole, 4, cylindrical cavity, 5, aluminium membrane, 6, conductive ink, 7, FEP membrane.

Detailed Description

The invention is further described below with reference to the drawings and examples.

In this embodiment, as shown in fig. 1-4, the equiangular spiral tube of the cochlea is stretched into a three-dimensional structure including an outer wall, an inner wall and a wall height. Since the length of the spiral tube 2 is related to the resonant frequency of the spiral tube 2, each different length corresponds to a different resonant frequency of the equiangular spiral resonant cavity. The height of the spiral tube 2 refers to the distance from the upper end face of the spiral tube 2 to the bottom plate 1, and the thickness of the bottom plate is 2mm. The wall thickness of the spiral tube 2 should be less than the average length and height of the spiral, and if the thickness of the spiral tube 2 is too thin or too thick, it will affect the performance of acoustic energy generation, causing interference. Since the spiral pipe 2 has a certain pipe width, which results in a large difference between the length dimension measured from the outside of the pipe and the length measured from the inside of the pipe, it is necessary to make an average and use it for the calculation of the resonance frequency, the wall thickness of the spiral pipe 2 is 2mm. The length of the spiral tube 2 is a reference quarter-wave tube, when the tube length is equal to one quarter of the wavelength, resonance occurs in the cavity, the resonance frequency is f=c/4L, wherein c is the sound velocity (340 m/s) in the air, L is the length of the quarter-wave tube, and the invention adopts the equiangular spiral tube, which is different from the traditional straight quarter-wave tube, so that the whole structure is more compact. In addition, unlike the conventional quarter wave tube, the present invention adopts an equiangular spiral tube, and if the path of the spiral tube 2 is a straight path, the outside-to-inside of the quarter wave tube in the present embodiment is tapered, so that the effect of amplifying sound pressure is more obvious. In addition, the height of the equiangular spiral pipe is far smaller than the average length of the pipe of the spiral structure; the length of 4 times of the average length of the pipeline of the equiangular spiral pipe is the corresponding sound wave wavelength when the quarter-wave pipe generates acoustic resonance. The average arc length of the equiangular spiral pipe 2 designed in the invention is 350.2mm, the height of the equiangular spiral pipe 2 is 40mm, the radius of a cylindrical groove arranged on the upper side of the cylindrical cavity is 25mm, the height of the cylindrical groove is 10mm, and the sound waves rub against the effective working areas of the circular areas with the sizes of 25mm radius of the aluminum film 5 and the FEP film 7 of the nano generator. The equiangular spiral pipe 2 has the function of enabling sound waves entering the equiangular spiral resonant cavity to reach a resonance state, storing sound wave energy in the equiangular spiral resonant cavity, better converting the sound waves after being coupled with the cylindrical resonant cavity and pushing the sound wave friction nano generator to work by utilizing the sound wave energy, and improving the output performance and the output efficiency of the sound wave friction nano generator.

The FEP film 7 can be used as a common material of an acoustic friction nano generator, and a layer of conductive electrode is usually required to be attached to the surface of the FEP film 7. The aluminum can be used as the material of the acoustic friction nano generator, has good conductivity and lower cost, has the advantage of being capable of being used as an electrode, the effective working area radius of the aluminum film 5 in the power generation unit is 25mm, the thickness of the aluminum film is 1mm, and small round holes with uniform density are distributed on the aluminum film, so that the contact area and the air flow are favorably balanced, and the acoustic friction nano generator can realize better contact and separation. Related studies have shown that smaller acoustic port sizes increase acoustic viscosity loss and thermoacoustic loss, and that the present invention distributes acoustic ports of uniform density with a diameter of 1.5mm and a spacing of 1 mm. The sound hole is used for communicating air in the cylindrical resonant cavity with a gap between the two films (the aluminum film 5 and the FEP film 7), so that positive and negative sound can act on two sides of the FEP film 7 to realize contact separation.

Fig. 5 shows the invention in experiments performed at a frequency range of 140Hz to 280Hz, and it can be seen from the graph that the output performance of the invention is not unidirectionally increased with increasing frequency, and when the amplitude of the sound wave is kept constant, the maximum output of the electric energy is obtained at a frequency of 210Hz, and the frequency is the resonance frequency of the invention, and when the frequency is far from the optimal frequency, the output electric energy of the invention is reduced, and the deviation rule of the optimal output frequency of the open circuit voltage of the invention is verified.

Thus, the optimal resonant frequency of the present invention is 210Hz.

Fig. 6 shows the output of the present invention at 90dB, 210Hz for an optimum open circuit voltage, with a maximum open circuit voltage of 29.7V.

FIG. 7 shows the output of the present invention for an optimum short-circuit current at 90dB, 210Hz, which can reach a maximum of 10.2 μA.

FIG. 8 shows the optimum transferred charge amount at 90dB and 210Hz, and the maximum transferred charge amount can reach 22.7nC.

Compared with the traditional electromagnetic and piezoelectric type acoustic-electric converters, the invention has the advantage of collecting acoustic energy at low frequency at high efficiency, and most acoustic energy in life is commonly existing at low frequency, so that the further effective collection of the acoustic energy at low frequency in life is beneficial to sustainable development of society.

The electric energy output by the invention can charge the capacitor after being rectified by the rectifier bridge, the charged acoustic wave friction nano generator can directly supply power to the LED lamp, the maximum output electric power is 324 mu W, compared with the output of most electromagnetic and piezoelectric type acoustic-electric converters in the past, the output electric energy is enough to supply power to small-sized sensors such as temperature and humidity sensors, and the small-sized sensor equipment can continuously work for a period of time.

The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims (6)

1. The utility model provides a sound wave friction nano generator based on bionical cochlea which characterized in that: comprises a spiral tube cavity, a cylindrical cavity (4) and a sonic friction nano generator;

the spiral tube cavity comprises a spiral tube (2) and a bottom plate (1), and the spiral tube (2) is an equiangular spiral tube; the bottom plate (1) is fixed at the lower end of the spiral tube (2);

the cylindrical cavity (4) is fixed at the upper end of the spiral tube (2); the upper side of the cylindrical cavity (4) is provided with a cylindrical groove, the bottom of the cylindrical groove is provided with a round hole (3), and the center of the round hole (3) is positioned on the central axis of the base circle of the equiangular spiral pipe;

the acoustic friction nano generator comprises an aluminum film (5), an electrode (6) and an FEP film (7); the FEP film (7) is a fluorinated ethylene propylene copolymer film; the aluminum film (5) is stuck to the periphery of the opening of the cylindrical groove, and a plurality of sound holes are formed in the aluminum film (5); the FEP film (7) is covered on the aluminum film (5), and the periphery of the FEP film (7) is adhered and fixed with the periphery of the aluminum film (5); the electrode (6) is a conductive ink printing electrode and is printed on the upper surface of the FEP film (7);

the upper end and the lower end of the spiral tube (2) respectively form an equiangular spiral resonant cavity with a cavity between the cylindrical cavity (4) and the bottom plate (1); a cylindrical resonant cavity is formed between the aluminum film (5) and the cylindrical groove;

the spiral tube cavity and the cylindrical cavity (4) form a bionic cochlea structure.

2. The bionic cochlea-based acoustic friction nano-generator according to claim 1, wherein: the spiral tube (2) and the bottom plate (1) are integral parts printed in a 3D mode, and an airtight space is formed in the working process of the equiangular spiral resonant cavity.

3. The bionic cochlea-based acoustic friction nano-generator according to claim 1, wherein: the lower surface of the cylindrical cavity (4) is the same as the shape and the size of the bottom plate (1).

4. The bionic cochlea-based acoustic friction nano-generator according to claim 1, wherein: the spiral tube (2) and the cylindrical cavity (4) are fixed by hot melt adhesive.

5. The bionic cochlea-based acoustic friction nano-generator according to claim 1, wherein: circular through holes with the diameter of 1.5mm and the longitudinal and transverse spacing of 1mm are uniformly distributed on the surface of the aluminum film (5).

6. The bionic cochlea-based acoustic friction nano-generator according to claim 1, wherein: the projection line of the spiral pipe (2) on the horizontal plane is an equiangular spiral curve and is expressed by the following formula:

x＝a*cos(t)*exp(b*t)

y＝a*sin(t)*exp(b*t)

wherein a is the initial radius of a base circle, b is tan (theta), theta is the diffusion angle of equiangular spiral, which is complementary to the equiangular phi, t is the angle parameter, the unit is radian, and the initial value is 0.

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