Method for improving piezoelectric constant and piezoelectric performance of eggshell membrane protein

Abstract

The application relates to a method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein, and relates to the field of protein extraction. The eggshell membrane protein-based material prepared in the application has good biocompatibility and air permeability, can adapt to complex deformation and more comfortably contact human skin; the eggshell membrane is treated by ultrasonic treatment and crosslinked by using glutaraldehyde, the molecular structure of the eggshell membrane protein is optimized, and the piezoelectric constant and piezoelectric performance of the eggshell membrane protein-based material are effectively improved; by improving the piezoelectric constant and piezoelectric performance of the eggshell membrane protein, the resource utilization of the waste eggshell membrane can be realized, which not only helps to reduce environmental pollution, but also can bring economic benefits and social benefits to related industries; in addition, the application provides a new high-performance material for the field of material science, which not only helps to promote the progress and development of material science, but also helps to promote the innovation of wearable devices and sensors and realize the resource utilization of waste.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of protein extraction, in particular to a method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein. BACKGROUND

[0002] With the continuous progress of material science, there is an increasing demand for new high-performance materials. Naturally available biological piezoelectric materials such as silk, cellulose, peptide fibers, collagen fibers, bacteriophages, etc. have been considered as promising alternatives for green energy harvesting materials. Collagen-based piezoelectric materials have attracted great interest due to their availability, relatively high longitudinal piezoelectric sensitivity (23.5 μV / Pa) and ease of processing. In recent years, wearable devices and sensors have been increasingly widely used in the fields of healthcare, physiological monitoring, human-computer interaction, etc. These devices have high requirements for the piezoelectric constant and piezoelectric performance of materials in order to achieve more sensitive and stable signal transmission and energy conversion.

[0003] Collagen is a common component in human skin, heart and cartilage, and also exists in eggshell membranes. As a kind of natural green material, eggshell membranes have the advantages of abundant source, low price and good biocompatibility. It is a highly collagenous thin fibrous porous membrane layer existing between the calcified eggshell and the egg white of chicken eggs. Eggshell membranes are composed of different types of collagen (I, V and X) and a variety of proteins such as bone proteins, keratins and salivary proteins. However, the original piezoelectric constant and piezoelectric performance of eggshell membranes often cannot meet the needs of high-end applications such as electronic devices, sensors, etc. In addition, its application in flexible sensors is limited by small size, irregular shape, brittleness and poor mechanical properties. In order to be used in devices, it is necessary to reshape the eggshell membranes into customized biomaterials.

[0004] Ultrasonic technology, as a non-thermal processing technology, has the advantages of high efficiency, environmental protection and easy control. In the field of material science, ultrasonic technology has been widely used to improve the microstructure and performance of materials. Eggshell membranes, as waste in the food industry, their recycling and high-value development conform to the trend of environmental protection and sustainable development. Improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein can expand its application in the field of electronic devices, sensors, etc. and realize the resource utilization of waste. The application of ultrasonic technology in the treatment of eggshell membrane protein is expected to optimize the molecular structure of eggshell membrane protein through the action of ultrasonic waves, improve its piezoelectric constant and piezoelectric performance, and thus expand its application range in the fields of electronics, biomedicine, etc. In summary, the research on improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein has important scientific significance and application value. This research not only helps to promote the progress and development of material science, but also helps to promote the innovation of wearable devices and sensors and realize the resource utilization of waste. SUMMARY

[0005] The purpose of the present application is to provide a method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein to solve the problems existing in the prior art.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is:

[0007] A method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein, the method comprising:

[0008] S1, peeling, cleaning and drying the eggshell membrane, and grinding the dried eggshell membrane into eggshell membrane powder by mechanical grinding;

[0009] S2, immersing the eggshell membrane powder in distilled water at a preset solid-liquid ratio and adjusting the pH with acetic acid to obtain an acid hydrolysis solution;

[0010] S3, adding a preset mass fraction of pepsin to the acid hydrolysis solution for enzymatic hydrolysis to obtain an enzymatic hydrolysis solution;

[0011] S4, ultrasonic treatment of the enzymatic hydrolysis solution, collection of the supernatant, pH adjustment with NaOH solution, salting-out, centrifugation, dialysis and freeze-drying of the supernatant to obtain extracted eggshell membrane protein;

[0012] S5, dissolving the eggshell membrane protein in hydrochloric acid and preparing a piezoelectric film by vacuum filtration;

[0013] S6, crosslinking the piezoelectric film with glutaraldehyde to obtain a modified eggshell membrane protein piezoelectric film.

[0014] In a possible implementation, in the step S2, the solid-liquid ratio of the eggshell membrane powder is 1:40-1:20 g / ml.

[0015] In a possible implementation, the step S2 comprises immersing the eggshell membrane powder in distilled water at a preset solid-liquid ratio and adjusting the pH to 1-1.5 with acetic acid to obtain an acid hydrolysis solution.

[0016] In a possible implementation, in the step S3, the mass fraction of the pepsin is 2-4%.

[0017] In a possible implementation, in the step S4, the power of the ultrasonic treatment is 300-400 W.

[0018] In a possible implementation, in the step S4, the NaCl concentration for salting-out of the supernatant is 1.5-4 mol / L.

[0019] In a possible implementation, the acetic acid concentration in the step S4 of dialyzing the supernatant is 0.5-0.8 mol / L.

[0020] In a possible implementation, the step S5 includes dissolving the eggshell membrane protein in hydrochloric acid with a concentration of 0.02-0.06 mol / L to prepare a piezoelectric film by vacuum filtration.

[0021] In a possible implementation, the step S5 includes dissolving the eggshell membrane protein with a mass fraction of 8-16% in hydrochloric acid with a concentration of 0.02-0.06 mol / L to prepare a piezoelectric film by vacuum filtration.

[0022] In a possible implementation, the step S6 includes crosslinking the piezoelectric film with glutaraldehyde for 10-30 min to obtain a modified eggshell membrane protein piezoelectric film.

[0023] The technical scheme provided in the application has at least the following beneficial effects:

[0024] The eggshell membrane protein-based material prepared in the application has good biocompatibility and air permeability, can adapt to complex deformation and more comfortably contact human skin; the ultrasonic treatment of the eggshell membrane and the crosslinking with glutaraldehyde optimize the molecular structure of the eggshell membrane protein, effectively improve the piezoelectric constant and piezoelectric performance of the eggshell membrane protein-based material; the improvement of the piezoelectric constant and piezoelectric performance of the eggshell membrane protein can realize the resource utilization of the waste eggshell membrane, which not only helps to reduce environmental pollution, but also can bring economic and social benefits to related industries; in addition, the application provides a new high-performance material for the field of material science, which not only helps to promote the progress and development of material science, but also helps to promote the innovation of wearable devices and sensors and realize the resource utilization of waste. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, illustrate the application together with the embodiments of the application, and are used to explain the application, but do not constitute a limitation on the application. In the drawings:

[0026] Figure 1 A flowchart of the method for improving the piezoelectric constant and piezoelectric performance of the eggshell membrane protein provided in the embodiment 1 of the application is shown;

[0027] Figure 2 A secondary structure test diagram of the eggshell membrane protein piezoelectric film prepared in the embodiment 2, the embodiment 3 and the embodiment 4 of the application is shown;

[0028] Figure 3Fig. 2 shows a diagram of the intermolecular force test of the eggshell membrane protein piezoelectric film prepared in Example 2, Example 3, and Example 4 of the present application;

[0029] Figure 4 Fig. 3 shows a diagram of the piezoelectric constant test of the eggshell membrane protein piezoelectric film prepared in Example 2, Example 3, and Example 4 of the present application;

[0030] Figure 5 Fig. 4 shows a diagram of the voltage test of the eggshell membrane protein piezoelectric film prepared in Example 2, Example 3, and Example 4 of the present application;

[0031] Figure 6 Fig. 5 shows a diagram of the current test of the eggshell membrane protein piezoelectric film prepared in Example 2, Example 3, and Example 4 of the present application. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0033] Wherein, the same parts are denoted by the same reference numerals. It should be noted that the words "front", "back", "left", "right", "up" and "down" used in the following description refer to the directions in the drawings of the present application, and the words "bottom surface" and "top surface", "inner" and "outer" refer to the directions towards or away from a particular part. In addition, the terms "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features with "first" and "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more.

[0034] The present application will be further described below with reference to the drawings and embodiments.

[0035] Embodiment 1

[0036] Figure 1 Fig. 1 shows a flowchart of the method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein provided by the present application, which comprises the following steps:

[0037] Step S1, peel, wash and dry the eggshell membrane, and grind the dried eggshell membrane into eggshell membrane powder by mechanical grinding.

[0038] Step S2, the eggshell membrane powder is immersed in distilled water at a preset solid-liquid ratio, and acetic acid is used to adjust the pH to obtain an acid hydrolysis solution.

[0039] Specifically, the eggshell membrane powder is immersed in distilled water at a preset solid-liquid ratio, and acetic acid is used to adjust the pH to 1-1.5 to obtain an acid hydrolysis solution. Optionally, the solid-liquid ratio of the eggshell membrane powder is 1:40-1:20 g / ml.

[0040] Step S3, a preset mass fraction of pepsin is added to the acid hydrolysis solution for enzymatic hydrolysis to obtain an enzymatic hydrolysis solution.

[0041] Optionally, the mass fraction of pepsin is 2-4%.

[0042] Step S4, the enzymatic hydrolysis solution is subjected to ultrasonic treatment, the supernatant is collected, the pH is adjusted with a NaOH solution, the supernatant is subjected to salting-out, centrifugation, dialysis, and freeze-drying to obtain extracted eggshell membrane protein.

[0043] Optionally, the power of the ultrasonic treatment is 300-400 W.

[0044] Optionally, the NaCl concentration for salting-out of the supernatant is 1.5-4 mol / L.

[0045] Optionally, the acetic acid concentration for dialysis of the supernatant is 0.5-0.8 mol / L.

[0046] Step S5, the eggshell membrane protein is dissolved in hydrochloric acid to prepare a piezoelectric film by vacuum filtration.

[0047] Specifically, the eggshell membrane protein is dissolved in hydrochloric acid with a concentration of 0.02-0.06 mol / L to prepare a piezoelectric film by vacuum filtration.

[0048] Further, the eggshell membrane protein with a mass fraction of 8-16% is dissolved in hydrochloric acid with a concentration of 0.02-0.06 mol / L to prepare a piezoelectric film by vacuum filtration.

[0049] Step S6, the piezoelectric film is crosslinked with glutaraldehyde to obtain a modified eggshell membrane protein piezoelectric film.

[0050] In detail, the piezoelectric film is crosslinked with glutaraldehyde for 10-30 min to obtain a modified eggshell membrane protein piezoelectric film.

[0051] In order to better understand the present application, one comparative example (Example 2) and two specific examples (Examples 3 and 4) are used to further illustrate the present application. It should be noted that the specific examples described in the examples are only a part of the examples of the present application, and do not limit the scope of protection of the present application.

[0052] Example 2: (comparative example, no ultrasonic treatment)

[0053] The present embodiment provides a flowchart of a method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein, which comprises the following steps:

[0054] Step S1, the eggshell membrane is peeled off, washed thoroughly with distilled water, and dried at room temperature. The dried eggshell membrane is ground into eggshell membrane powder by mechanical grinding, and stored in a clean packaging bag at -18°C for standby use;

[0055] Step S2, the above eggshell membrane powder is immersed in distilled water at a solid-liquid ratio of 1:40, and the pH is adjusted to 1 with 0.5 mol / L acetic acid to obtain an acid hydrolysis solution;

[0056] Step S3, 2% by mass of pepsin is added to the acid hydrolysis solution for enzymatic hydrolysis to obtain an enzymatic hydrolysis solution;

[0057] Step S4, the supernatant of the enzymatic hydrolysis solution is collected, the pH is adjusted to 7-8 with 2.5 mol / L NaOH solution, the supernatant is added to a 4 mol / L NaCl solution, and stored at 4°C overnight, and centrifuged at 8000 r / min for 15 min. The obtained precipitate is dissolved in a 0.5 mol / L acetic acid solution, then dialyzed in a dialysis membrane with a molecular weight of 8-14 kDa for 48 h with 0.1 mol / L acetic acid, and the solution is changed every 6 h. Then the solution is dialyzed in distilled water until the pH value reaches neutral. Finally, the dialysate is freeze-dried to obtain the desired eggshell membrane protein;

[0058] Step S5, the eggshell membrane protein is dissolved in 0.02 mol / L hydrochloric acid to prepare a 10% by mass eggshell membrane protein solution, and a piezoelectric film is prepared by vacuum filtration;

[0059] Step S6, the piezoelectric film is crosslinked with glutaraldehyde for 10 min to obtain a modified eggshell membrane protein piezoelectric film.

[0060] Example 3:

[0061] The present embodiment provides a flowchart of a method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein, which comprises the following steps:

[0062] Step S1, the eggshell membrane is peeled off, washed thoroughly with distilled water, and dried at room temperature. The dried eggshell membrane is ground into eggshell membrane powder by mechanical grinding, and stored in a clean packaging bag at -18°C for standby use;

[0063] Step S2, the above eggshell membrane powder is immersed in distilled water at a solid-liquid ratio of 1:40, and the pH is adjusted to 1 with 0.5 mol / L acetic acid to obtain an acid hydrolysis solution;

[0064] Step S3, 2% by mass of pepsin is added to the acid hydrolysis solution for enzymatic hydrolysis to obtain an enzymatic hydrolysis solution;

[0065] Step S4, the enzymatic hydrolysis solution is subjected to ultrasonic treatment at a power of 300 W, and the supernatant of the enzymatic hydrolysis solution with and without ultrasonic pretreatment is collected, the pH is adjusted to 7-8 with a 2.5 mol / L NaOH solution, the supernatant is added to a 4 mol / L NaCl solution, and the mixture is stored at 4°C overnight, and then centrifuged at 8000 r / min for 15 min, the obtained precipitate is dissolved in a 0.5 mol / L acetic acid solution, and then the solution is dialyzed in a dialysis membrane with a molecular weight of 8-14 kDa against a 0.1 mol / L acetic acid solution for 48 h, and the solution is replaced every 6 h, followed by dialysis against distilled water until the pH value reaches neutral, and finally the dialysate is freeze-dried to obtain the desired eggshell membrane protein;

[0066] Step S5, the eggshell membrane protein is dissolved in a 0.02 mol / L hydrochloric acid solution to prepare a 10% by mass eggshell membrane protein solution, and a piezoelectric film is prepared by vacuum filtration;

[0067] Step S6, the piezoelectric film is crosslinked with glutaraldehyde for 10 min to obtain a modified eggshell membrane protein piezoelectric film.

[0068] Example 4:

[0069] The embodiment provides a flowchart of a method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein, and the method comprises the following steps:

[0070] Step S1, the eggshell membrane is peeled off, washed thoroughly with distilled water, and dried at room temperature, the dried eggshell membrane is ground into an eggshell membrane powder by mechanical grinding, and the powder is stored in a clean packaging bag at -18°C for standby use;

[0071] Step S2, the eggshell membrane powder is immersed in distilled water at a solid-liquid ratio of 1:30, and the pH is adjusted to 1.5 with a 0.5 mol / L acetic acid solution to obtain an acid hydrolysis solution;

[0072] Step S3, 3% by mass of pepsin is added to the acid hydrolysis solution for enzymatic hydrolysis to obtain an enzymatic hydrolysis solution;

[0073] Step S4, ultrasonic treatment is performed on the enzymatic hydrolysate at a power of 300 W, the supernatant of the ultrasonic pretreated and non-ultrasonic pretreated enzymatic hydrolysate is collected, the pH is adjusted to 7-8 by using 2.5 mol / L NaOH solution, the supernatant is added into 4 mol / L NaCl, and is stored at 4℃ overnight, and is centrifuged at 8000 r / min for 15 min, the obtained precipitate is dissolved in 0.5 mol / L acetic acid solution, and then is dialyzed in a dialysis membrane with a molecular weight of 8-14 kDa by using 0.1 mol / L acetic acid for 48 h, the solution is changed every 6 h, then the solution is dialyzed in distilled water until the pH value reaches neutral, and finally the dialysate is freeze-dried to obtain the desired eggshell membrane protein;

[0074] Step S5, the eggshell membrane protein is dissolved in 0.05 mol / L hydrochloric acid to prepare an eggshell membrane protein solution with a mass fraction of 15%, and a piezoelectric film is prepared by vacuum filtration;

[0075] Step S6, the piezoelectric film is crosslinked by using glutaraldehyde for 20 min to obtain a modified eggshell membrane protein piezoelectric film.

[0076] Performance test:

[0077] Figure 2The secondary structure of the eggshell membrane protein piezoelectric thin films prepared in Example 2, Example 3, and Example 4 was tested. The amide I band in the Fourier spectrum includes α-helix, β-sheet, β-turn, and random coil structures, which are commonly used to analyze the secondary structure of proteins. As can be seen from the figure, compared with the eggshell membrane protein without ultrasonic treatment (Example 2), the content of α-helix and β-turn in the eggshell membrane protein after ultrasonic treatment (Example 3 and Example 4) decreases, and the content of β-sheet and random coil increases. The cavitation effect produced by ultrasonic waves produces strong shock waves and micro-jets, which produce mechanical impact on protein molecules, destroy their original structure, and cause changes in intermolecular interaction forces (such as hydrogen bonds, hydrophobic interactions, etc.), thereby making the structure of the protein loose. α-helix is a stable and tight structure in proteins, mainly maintained by hydrogen bonds. The cavitation effect and mechanical action of ultrasonic waves will destroy these hydrogen bonds, causing the α-helix structure to partially unfold or break, thereby causing its content to decrease. With the decrease of α-helix, other structural elements in the protein molecule (such as β-sheet) can relatively increase. β-sheet is a relatively loose structure, and its formation helps the rearrangement and conformational change of protein molecules after ultrasonic treatment. β-turn is a flexible structure in proteins that connects different peptide segments. Ultrasonic treatment can affect the content of β-turn by changing the overall conformation of protein molecules. However, due to the structural characteristics of β-turn itself, its content change may not be as significant as α-helix and β-sheet. Random coil is a disordered structure in proteins, and its increase in content usually indicates that the protein molecules become more loose and flexible. Ultrasonic treatment destroys the interaction forces within the protein molecules, making their structure loose, thereby promoting the formation of random coil.

[0078] Figure 3The intermolecular force test diagram of the eggshell membrane protein piezoelectric thin film prepared by the application embodiment 2, embodiment 3, embodiment 4 is shown. The intermolecular force of the eggshell membrane protein is mainly ion bond, hydrogen bond, hydrophobic interaction and disulfide bond. Among them, the hydrophobic interaction is the main force to maintain the protein structure, the disulfide bond is the second, and the hydrogen bond and the ion bond contribute less. As can be seen from the figure, the ion bond content of embodiments 2, 3 and 4 is low, and there is little difference before and after ultrasonic treatment, which shows that the ion bond is not the main force to maintain the molecular structure of the eggshell membrane protein. Compared with embodiment 2, the hydrogen bond content of embodiments 3 and 4 is significantly reduced. The cavitation effect of ultrasonic wave can produce bubbles in the liquid and make them expand and break rapidly. The shear force and microjet generated in this process can destroy the hydrogen bond between protein molecules, and the α-helix is converted into β-fold structure which is more conducive to gel structure. The change trend of α-helix and β-fold is consistent. The hydrophobic interaction force is also significantly enhanced. Through the formation of local high temperature and shear force, ultrasonic wave can promote the exposure of hydrophobic groups inside the protein molecule and enhance the hydrophobic interaction. The increase of disulfide bond content is mainly due to the oxidation of exposed sulfhydryl groups inside the molecule.

[0079] Figure 4 The piezoelectric constant test diagram of the eggshell membrane protein piezoelectric thin film prepared by the application embodiment 2, embodiment 3, embodiment 4 is shown. Compared with embodiment 2, the piezoelectric constant d 33 of embodiments 3 and 4 is increased by 2.16 times and 2.29 times respectively. The cavitation effect of ultrasonic wave can produce mechanical impact on protein molecules, thereby destroying their original structure and making them become more loose and flexible. This structural change may be conducive to the directional arrangement and polarization of protein molecules in the electric field. Ultrasonic wave can also produce shear force and turbulent flow in the liquid, which can further promote the dispersion and rearrangement of protein molecules. The shear force can reduce the particle size of protein molecules and increase their specific surface area, thereby enhancing the interaction between protein molecules and electric field. Turbulent flow helps to break the aggregation state of protein molecules, making them more easily respond in the electric field. At the same time, ultrasonic treatment can also cause changes in the tertiary structure of protein, such as exposing more charged groups or hydrophobic groups. The directional arrangement and polarization of these groups in the electric field can also increase the piezoelectric constant.

[0080] Figure 5 and Figure 6The voltage and current test figures of the eggshell membrane protein piezoelectric thin film prepared by the application embodiment 2, embodiment 3 and embodiment 4 are shown respectively. Similar to the change trend of the secondary structure of the eggshell membrane protein and the piezoelectric constant, the ultrasonic treatment significantly improves the piezoelectric performance of the eggshell membrane protein. The ultrasonic treatment improves the piezoelectric performance of the protein molecules by changing the structure, surface charge and hydrophobicity, intermolecular interaction, and solubility and dispersibility of the protein molecules. These changes make the protein molecules more easily oriented and polarized in the electric field, thereby producing a stronger piezoelectric effect.

[0081] In summary, the eggshell membrane protein-based material prepared by the application has good biocompatibility and air permeability, can adapt to complex deformation and more comfortably contact the human skin; by ultrasonic treatment of the eggshell membrane and cross-linking using glutaraldehyde, the molecular structure of the eggshell membrane protein is optimized, and the piezoelectric constant and piezoelectric performance of the eggshell membrane protein-based material are effectively improved; by improving the piezoelectric constant and piezoelectric performance of the eggshell membrane protein, the resource utilization of the waste eggshell membrane can be realized, which not only helps to reduce environmental pollution, but also can bring economic and social benefits to the related industry; in addition, the application provides a new high-performance material for the field of material science, which not only helps to promote the progress and development of material science, but also helps to promote the innovation of wearable devices and sensors and realize the resource utilization of waste.

[0082] The above only describes the preferred embodiments of the application, and it should be pointed out that for ordinary skilled persons in the technical field, several improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements should also be considered as the protection scope of the application.

Claims

1. A method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein, characterized in that the method comprises: S1. Stripping, cleaning and drying the eggshell membrane, and grinding the dried eggshell membrane into eggshell membrane powder by mechanical grinding; S2. Immersing the eggshell membrane powder in distilled water at a preset solid-liquid ratio, and adjusting the pH with acetic acid to obtain an acid hydrolysis solution; S3. Adding a preset mass fraction of pepsin to the acid hydrolysis solution for enzymatic hydrolysis to obtain an enzymatic hydrolysis solution; S4. Ultrasonic treatment of the enzymatic hydrolysis solution, collection of the supernatant, adjustment of the pH with NaOH solution, salting-out, centrifugation, dialysis and freeze-drying of the supernatant to obtain extracted eggshell membrane protein; S5. Dissolving the eggshell membrane protein in hydrochloric acid and preparing a piezoelectric film by vacuum filtration; S6. Crosslinking the piezoelectric film with glutaraldehyde to obtain a modified eggshell membrane protein piezoelectric film; in the step S4: the power of the ultrasonic treatment is 300-400 W.

2. The method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein according to claim 1, characterized in that in the step S2: the solid-liquid ratio of the eggshell membrane powder is 1:40-1:20 g / ml.

3. The method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein according to claim 1, characterized in that the step S2 comprises: immersing the eggshell membrane powder in distilled water at a preset solid-liquid ratio, and adjusting the pH to 1-1.5 with acetic acid to obtain an acid hydrolysis solution.

4. The method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein according to claim 1, characterized in that in the step S3: the mass fraction of pepsin is 2-4%.

5. The method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein according to claim 1, characterized in that in the step S4: the NaCl concentration for salting-out of the supernatant is 1.5-4 mol / L.

6. The method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein according to claim 1, characterized in that in the step S4: the acetic acid concentration for dialysis of the supernatant is 0.5-0.8 mol / L.

7. The method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein according to claim 1, characterized in that the step S5 comprises: dissolving the eggshell membrane protein in hydrochloric acid with a concentration of 0.02-0.06 mol / L, and preparing a piezoelectric film by vacuum filtration.

8. The method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein according to claim 7, characterized in that the step S5 comprises: dissolving eggshell membrane protein with a mass fraction of 8-16% in hydrochloric acid with a concentration of 0.02-0.06 mol / L, and preparing a piezoelectric film by vacuum filtration.

9. The method for improving the piezoelectric constant and piezoelectric performance of eggshell membrane protein according to claim 1, characterized in that the step S6 comprises: crosslinking the piezoelectric film with glutaraldehyde for 10-30 min to obtain a modified eggshell membrane protein piezoelectric film. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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