Method for improving the piezoelectric properties of regenerated eggshell membrane

Abstract

The present application is about a method for improving the piezoelectric properties of regenerated eggshell membranes, and relates to the field of fiber membranes. The method comprises: pre-treating waste eggshell membranes to obtain eggshell membrane powder; dissolving the eggshell membrane powder in an aqueous solution and stirring until fully dissolved to obtain an eggshell membrane aqueous solution; adding a PEO polymer to the eggshell membrane aqueous solution and stirring fully to obtain a spinning solution; electrospinning the spinning solution in an electrostatic spinning machine to obtain a nanofiber membrane made of waste eggshell inner membranes; encapsulating the nanofiber membrane with PDMS and a curing agent to obtain a flexible piezoelectric sensor. The nanofiber membrane prepared in the present application has good biocompatibility and degradability. After encapsulating the nanofiber membrane with PDMS and a curing agent, a flexible piezoelectric sensor is obtained, which produces a significant piezoelectric response under the excitation of a small vibration, and can become a source of alternative green energy to power various portable electronic devices used in daily life.

Description

Technical Field

[0001] The present application relates to the field of fiber membrane technology, and in particular to a method for improving the piezoelectric properties of regenerated eggshell membrane. Background Art

[0002] my country is the country with the largest number of poultry farmers in the world, and its egg production ranks first in the world. With the increasing production and consumption of poultry eggs, the number of discarded eggshells is also increasing, which not only causes serious pollution to the environment, but also is an extreme waste of resources. These discarded eggshells contain hard egg shells and eggshell inner membranes with many effective ingredients, which are valuable raw materials for feed, medicine, food and other industries. Although some relatively mature research on eggshells has been carried out at home and abroad, such as the application of eggshell powder in food and medical fields, there is little research on the recovery and utilization of protein in the eggshell inner membrane.

[0003] The inner membrane of the eggshell (commonly known as "phoenix coat") is a fibrous biological film with a double-layer membrane structure located between the eggshell and the egg white. It has good air permeability, adsorption, moisture retention, stability and other characteristics. The eggshell membrane contains about 90% protein, 2% carbohydrates and 3% liposomes, of which the proteins are collagen, keratin, ovalbumin, lysozyme, etc. At present, eggshell membranes are widely used in the fields of medicine, light industry and daily cosmetics, such as promoting wound recovery and promoting smooth and delicate skin. At present, medical and health care textiles are generally in close contact with human skin, the fabric surface is relatively rough, and the skin affinity is poor, which is not conducive to the healing of wounds.

[0004] The eggshell membrane itself presents a relatively tight three-dimensional network structure, with good biocompatibility, biodegradability and the characteristics of promoting skin metabolism. The large fiber specific surface area gives it good adsorption. However, directly using the eggshell membrane on the human body surface will reduce its fit with the skin and reduce comfort. The eggshell membrane is brittle after drying, and its strength and durability are poor. In addition, the protein contained in the eggshell membrane will only show good functional properties in a dissolved state. The requirements for biomass activity, biocompatibility and biodegradability in the textile medical field are increasing, so there is a certain research value in the application of eggshell membrane in the textile field.

[0005] Electrospinning is a simple and efficient process for preparing polymer micro-nano fibers. It has the common advantages of low equipment and experimental costs, high fiber yield, and wide applicability. The prepared fibers have a three-dimensional spatial structure, large specific surface area, small pore size, high porosity and good continuity, and have attracted much attention in recent years.

[0006] Patent CN110592686B discloses a micro-nano composite membrane loaded with growth factors, which is composed of an eggshell membrane loaded with growth factors, a protein membrane, a hydrophilic micro-nano fiber layer and a hydrophobic micro-nano fiber layer. The eggshell membrane is used as a direct carrier of the growth factor, and the protein is deposited as a coating layer on the surface of the eggshell membrane loaded with growth factors by salting out to form a protein membrane, and then the hydrophilic micro-nano fiber membrane and the hydrophobic micro-nano fiber membrane are sequentially wrapped on the surface of the protein membrane by electrospinning technology; the protein membrane is obtained by salting out and depositing poultry egg white.

[0007] There are few studies on the piezoelectric properties of eggshell membranes in related technologies, and most of them directly use eggshell membranes for the preparation of sensors. However, eggshell membranes are brittle after drying, have weak adhesion, and have poor mechanical properties. Directly using eggshell membranes to prepare sensors will reduce the firmness and stability of the sensors, and the weak electrical signals generated are not enough to power small electrical appliances. Electrospinning is a simple and efficient process for preparing polymer micro-nano fibers. The fibers prepared have a three-dimensional spatial structure, a large specific surface area, a small pore size, a high porosity, and good continuity. They have attracted much attention in recent years. The mechanical strength and piezoelectric properties of the fiber membrane can be improved by blending eggshell membranes with some polymers through the electrospinning process. Therefore, it is necessary to study methods to improve the piezoelectric properties of regenerated eggshell membranes. Summary of the invention

[0008] The purpose of this application is to provide a method for improving the piezoelectric properties of regenerated eggshell membrane, so as to solve the problem that directly using eggshell membrane to prepare sensors in the above-mentioned prior art will reduce the firmness and stability of the sensors, and the weak electrical signals generated are not sufficient to power small electrical appliances.

[0009] To achieve the above purpose, the technical solution adopted in this application is:

[0010] In one aspect, the present application provides a method for improving the piezoelectric properties of regenerated eggshell membrane, comprising:

[0011] S1, pretreating waste eggshell membranes to obtain eggshell membrane powder;

[0012] S2, dissolving the eggshell membrane powder obtained in step S1 in an aqueous solution and stirring until the eggshell membrane powder is fully dissolved to obtain an eggshell membrane aqueous solution;

[0013] S3, adding PEO polymer to the eggshell membrane aqueous solution obtained in step S2 and stirring them sufficiently to obtain a spinning solution;

[0014] S4, electrospinning the spinning solution obtained in step S3 in an electrospinning machine to obtain a nanofiber membrane using waste eggshell inner membrane as a raw material;

[0015] S5. Encapsulate the nanofiber membrane obtained in step S4 using PDMS and a curing agent to obtain a flexible piezoelectric sensor.

[0016] In a possible implementation, in step S1, pre-treating the waste eggshell membranes to obtain eggshell membrane powder comprises:

[0017] S11. Break fresh eggs and clean the white through blunt end;

[0018] S12, washing the eggshells thoroughly several times with ultrapure deionized water, and peeling off the eggshell membrane from the eggshells;

[0019] S13, washing the eggshell membrane with ethanol and deionized water to remove trace albumin;

[0020] S14, drying the eggshell membrane in a drying oven and grinding it into powder to obtain eggshell membrane powder.

[0021] In a possible implementation, the ethanol concentration in step S13 is 40-60%.

[0022] In a possible implementation, in step S14, the temperature of drying the eggshell membrane in a drying oven is set to 60-100°C.

[0023] In a possible implementation, in step S14, the drying time of the eggshell membrane in the drying oven is set to 30-50 minutes.

[0024] In a possible implementation, the mass ratio of PEO to eggshell membrane powder in the spinning solution obtained in step S3 is 1:2-2:1; and the concentration of the spinning solution is 15%-25%.

[0025] In a possible implementation, in step S4, the spinning rate applied when the spinning solution is electrospun in the electrospinning machine is 0.3-0.5 mL / h.

[0026] In a possible implementation, in step S4, the spinning temperature applied when the spinning solution is electrospun in the electrospinning machine is 25-35° C.; the spinning humidity applied when the spinning solution is electrospinned in the electrospinning machine is 45-65%.

[0027] In a possible implementation, in the step S5, the ratio of the PDMS to the curing agent is 10:1.

[0028] On the other hand, the present application provides an application of a flexible piezoelectric sensor prepared according to any of the above-mentioned methods for improving the piezoelectric properties of regenerated eggshell membrane in the fields of smart wearable devices, health monitoring and energy storage.

[0029] The beneficial effects of the technical solution provided by this application include at least:

[0030] (1) The eggshell membrane used in this application is a waste in the environment. It is non-toxic, cheap and the most abundant biological waste. The various proteins in the eggshell membrane are used as natural biological materials to achieve waste recycling, reflecting the concept of resource recycling and green environmental protection;

[0031] (2) Based on the electrospinning technology, the present application uses PEO polymer and eggshell membrane for blending to further prepare a fiber membrane with a nanostructure. By applying a high-voltage electrostatic field, the porous thin layer and highly collagenized fiber membrane structure of the eggshell membrane are reorganized in an orderly manner, so that the fibers in the fiber membrane have good orientation, certain flexibility and strength, and increase the overall stability of the fiber membrane;

[0032] (3) The present application controls the drying temperature and duration of the eggshell membrane, adjusts the mass ratio of PEO to eggshell membrane and solution concentration, spinning flow rate, voltage, collection drum speed, temperature and humidity and other parameters to ensure the uniformity of fiber diameter and distribution, while increasing the β-phase content in the nanofiber membrane, thereby improving its piezoelectric output;

[0033] (4) The nanofiber membrane prepared in the present application has good biocompatibility and degradability. After the nanofiber membrane is encapsulated using PDMS and a curing agent, a flexible piezoelectric sensor is obtained. When stimulated by a small vibration, a significant piezoelectric response is generated, which can become an alternative source of green energy to power various portable electronic devices used in daily life. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0035] Figure 1 A schematic flow chart of a method for improving the piezoelectric properties of regenerated eggshell membrane provided by an exemplary embodiment of the present application is shown;

[0036] Figure 2 A schematic diagram showing the mechanism of increasing the drying temperature and duration in Example 3 of the present application is shown;

[0037] Figure 3 A schematic diagram showing the mechanism of increasing the PEO content and the spinning solution concentration in Example 4 of the present application is shown;

[0038] Figure 4 A schematic diagram showing the viscosity test results of the spinning solutions in Example 2 and Example 5 of the present application is shown;

[0039] Figure 5 A schematic diagram of the mechanism of increasing the spinning rate and the spinning temperature and humidity in Example 5 of the present application is shown;

[0040] Figure 6 A schematic diagram showing the piezoelectric performance test results of the flexible piezoelectric sensor prepared in Example 2 of the present application is shown;

[0041] Figure 7 A schematic diagram showing the piezoelectric performance test results of the flexible piezoelectric sensor prepared in Example 3 of the present application is shown;

[0042] Figure 8 A schematic diagram showing the piezoelectric performance test results of the flexible piezoelectric sensor prepared in Example 4 of the present application is shown;

[0043] Fig. 9 A schematic diagram showing the piezoelectric performance test results of the flexible piezoelectric sensor prepared in Example 5 of the present application is shown. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0045] The present application is further described below in conjunction with the accompanying drawings and embodiments.

[0046] First, a brief introduction is given to the terms involved in the embodiments of the present application:

[0047] PEO, also known as polyethylene oxide, is a high molecular polymer with the appearance of small white granular powder. It has good water solubility, high viscosity, and good lubricity. Even a small amount of addition can show good fiber dispersion effect.

[0048] PDMS, polydimethylsiloxane, is a hydrophobic silicone material; it is used in various fields such as medicine, daily chemical products, food, and construction. It has hundreds of derivatives. Commonly used polysiloxanes include: polydimethylsiloxane, cyclomethicone, aminosiloxane, polymethylphenylsiloxane, polyether polysiloxane copolymer, etc.; among them, polydimethylsiloxane is a commonly used polysiloxane.

[0049] Embodiment 1

[0050] Figure 1A schematic flow chart of a method for improving the piezoelectric properties of regenerated eggshell membrane provided by an exemplary embodiment of the present application is shown, the method comprising:

[0051] Step S1, pre-treating waste eggshell membranes to obtain eggshell membrane powder;

[0052] Step S2, dissolving the eggshell membrane powder obtained in step S1 in an aqueous solution and stirring until the eggshell membrane powder is fully dissolved to obtain an eggshell membrane aqueous solution;

[0053] Step S3, adding PEO polymer to the eggshell membrane aqueous solution obtained in step S2 and stirring them sufficiently to obtain a spinning solution;

[0054] Step S4, electrospinning the spinning solution obtained in step S3 in an electrospinning machine to obtain a nanofiber membrane using the waste eggshell inner membrane as a raw material;

[0055] Step S5: encapsulate the nanofiber membrane obtained in step S4 using PDMS and a curing agent to obtain a flexible piezoelectric sensor.

[0056] In a preferred embodiment, in step S1, pre-treating waste eggshell membranes to obtain eggshell membrane powder comprises:

[0057] Step S11, breaking fresh eggs and clearing the white through blunt end;

[0058] Step S12, thoroughly washing the eggshell with ultrapure deionized water for several times, and peeling off the eggshell membrane from the eggshell;

[0059] Step S13, washing the eggshell membrane with ethanol and deionized water to remove trace albumin;

[0060] Step S14, drying the eggshell membrane in a drying oven and grinding it into powder to obtain eggshell membrane powder.

[0061] It should be noted that the β-phase content in the fiber membrane can be increased by controlling the drying temperature and duration of the eggshell membrane in the drying oven, thereby enhancing the piezoelectric signal output; by adjusting the mass ratio of PEO to eggshell membrane powder and adjusting the concentration of the spinning solution, the requirements for spinning on the machine can be achieved, the film-forming property of the spinning solution can be ensured, and the piezoelectric output can be improved; by adjusting parameters such as the spinning rate, voltage, collection roller speed, and spinning temperature and humidity, the uniformity of the fiber diameter and distribution can be ensured, thereby ensuring the stability of the piezoelectric output.

[0062] Furthermore, the ethanol concentration in step S13 is 40-60%.

[0063] Preferably, in step S14, the temperature of drying the eggshell membrane in a drying oven is set to 60-100°C.

[0064] Optionally, in step S14, the drying time of the eggshell membrane in the drying oven is set to 30-50 min.

[0065] Furthermore, the mass ratio of PEO to eggshell membrane powder in the spinning solution obtained in step S3 is 1:2-2:1; and the concentration of the spinning solution is 15%-25%.

[0066] Optionally, in step S4, the spinning rate applied when the spinning solution is electrospun in the electrospinning machine is 0.3-0.5 mL / h.

[0067] Preferably, in step S4, the spinning temperature applied when the spinning solution is electrospun in the electrospinning machine is 25-35° C.; the spinning humidity applied when the spinning solution is electrospinned in the electrospinning machine is 45-65%.

[0068] In one example, in step S5, the ratio of PDMS to curing agent is 10:1.

[0069] In summary, the present application is based on electrospinning technology, and uses PEO polymer and eggshell membrane for blending to further prepare a fiber membrane with a nanostructure. By using an applied high-voltage electrostatic field, the porous thin layer and highly collagenized fiber membrane structure of the eggshell membrane itself are re-combined in an orderly manner, so that the fibers in the fiber membrane have good orientation, and have certain flexibility and strength, thereby increasing the overall stability of the fiber membrane; by controlling the drying temperature and duration of the eggshell membrane, adjusting the mass ratio of PEO to eggshell membrane and solution concentration, spinning flow rate, voltage, collection drum speed, temperature and humidity and other parameters, the uniformity of fiber diameter and distribution is ensured, and at the same time, the β-phase content in the nanofiber membrane is increased, thereby improving its piezoelectric output; the nanofiber membrane prepared in the present application has good biocompatibility and degradability, and a flexible piezoelectric sensor is obtained by encapsulating the nanofiber membrane with PDMS and a curing agent, which produces a significant piezoelectric response under the excitation of a small vibration, and can become a source of alternative green energy to power various portable electronic devices used in daily life.

[0070] Embodiment 2

[0071] This embodiment provides a method for improving the piezoelectric properties of regenerated eggshell membrane, and the specific steps are as follows:

[0072] (1) Pretreatment of discarded eggshell membranes: fresh eggs were broken and the white albumin was removed by blunt end treatment; the eggshells were then thoroughly washed several times with ultrapure deionized water, and the eggshell membranes were carefully peeled off from the eggshells; the inner eggshell membranes were washed with ethanol and deionized water to remove trace albumin; the eggshell membranes were dried in a drying oven at 60°C for 30 minutes and then made into powder.

[0073] (2) Preparation of electrospinning solution: Dried eggshell membrane powder and PEO

[0074] Eggshell membrane / poly(ethylene oxide) (PEO) blends were prepared by directly adding 400,000 g / mol (400,000 g / mol) into an aqueous solution (30 ml), wherein the mass ratio of PEO to eggshell membrane powder was 1:2, yielding a 15 wt % eggshell membrane / PEO solution (i.e., the concentration of the spinning solution was 15%).

[0075] (3) Preparation of electrospinning fiber membrane: The electrospinning equipment used in this study was produced by Dalian Tesman Technology Co., Ltd.; during the electrospinning process, the electrospinning solution prepared in the previous step was filled into a 10 mL syringe equipped with a 19-gauge steel needle (needle inner diameter of 0.5 mm); after removing the bubbles in the syringe, the syringe was fixed on a syringe pump (Pfeder, model: 57BYG250B-8); the steel needle was connected to a TCM6002 high-voltage DC power supply through a tungsten electrode; a potential of 20 kV was applied to the tip of the injection needle; the distance between the steel needle and the collecting roller (grounded aluminum foil) was about 10 cm; the applied spinning rate was 0.3 mL / h; the collecting roller rotated at a speed of 400 rpm; the spinning temperature was 25°C, and the spinning humidity was 45%; after electrospinning, the aluminum foil with the forming pad was immediately removed from the collecting roller and placed in a hood for 24 hours to remove residual organic solvents and moisture.

[0076] (4) Preparation of flexible piezoelectric sensor: The nanofiber membrane obtained in the previous step was encapsulated using PDMS (10 ml) and curing agent (1 ml) in a ratio of 10:1 and dried in a vacuum drying oven at 100°C for 30 minutes to obtain a flexible piezoelectric sensor. The piezoelectric performance of the prepared flexible piezoelectric sensor was then tested.

[0077] Embodiment 3

[0078] This embodiment provides a method for improving the piezoelectric properties of regenerated eggshell membranes. The specific steps are basically the same as those of the second embodiment, except that when the cleaned eggshell membranes are dried in a drying oven, the drying temperature is adjusted to 80°C and the drying time is extended to 40 minutes. Figure 2 As shown in the figure, the eggshell membrane has highly collagenized protein fibers, which are composed of three polypeptide chains (α-chains) forming a triple helix structure, and each helix structure contains various amino acid molecules such as glycine, proline, and hydroxyproline. When the temperature of the eggshell membrane is increased, displacement occurs between the molecules, enhancing the polarization effect. In addition, there are amide, carbonyl and -OH parts in the eggshell membrane, which are closely connected to each other through strong hydrogen bonds and dipole moments. Their arrangement in the microfibers contributes to the piezoelectric properties in the eggshell membrane.

[0079] Embodiment 4

[0080] This embodiment provides a method for improving the piezoelectric properties of regenerated eggshell membrane. The specific steps are basically the same as those in the second embodiment, except that the mass ratio of PEO to eggshell membrane powder is increased to 2:1, and the concentration of spinning solution is increased to 20%. Figure 3 and Figure 4 As shown in the figure, when the PEO content and the spinning solution concentration are increased, the viscosity of the spinning solution increases from the original 192mPa·s to 3200mPa·s. Under the action of the high voltage electric field, mechanical stretching will occur due to electrostatic interaction, thereby increasing the β-phase content of the fiber membrane and improving the piezoelectric output.

[0081] Embodiment 5

[0082] This embodiment provides a method for improving the piezoelectric properties of regenerated eggshell membrane. The specific steps are basically the same as those in the second embodiment, except that the spinning rate is increased to 0.5 mL / h, and the spinning temperature and humidity are adjusted to 35°C and 65%, respectively. Figure 5 As shown, when the spinning rate is increased, a relatively uniformly distributed fiber morphology is formed under the action of the electric field force, and under conditions of high temperature and humidity, excess water can evaporate in time, reducing droplets on the surface of the fiber membrane and ensuring the uniformity of the fiber diameter. Under external excitation, the fiber membrane can be evenly stressed, thereby ensuring the stability of the piezoelectric signal output.

[0083] Effect verification

[0084] like Figure 6-Figure 9 As shown in the figure, the piezoelectric performance test results of the flexible piezoelectric sensors prepared in Example 2 to Example 5 are respectively shown. It can be seen that by controlling the drying temperature and time of the eggshell membrane, adjusting the mass ratio of PEO to eggshell membrane powder, and the concentration of the spinning solution, the spinning rate, and the spinning temperature and humidity and other parameters, the output voltage of the flexible piezoelectric sensor is increased from the original 1.28V to 1.8V, 2.6V and 3.1V, respectively, and the piezoelectric signal is greatly improved, which proves the feasibility of the method.

[0085] In summary,

[0086] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for improving the piezoelectric properties of regenerated eggshell membrane based on high eggshell membrane / PEO content, characterized in that: include: (1) Pretreatment of waste eggshell membranes: Fresh eggs were cracked and the whites were cleaned by blunt end; Then, the eggshell is thoroughly washed several times with ultrapure deionized water, and the eggshell membrane is carefully peeled off from the eggshell; the inner eggshell membrane is washed with ethanol and deionized water to remove trace albumin; the eggshell membrane is dried in a drying oven at 60° C. for 30 minutes and then made into powder, thereby obtaining dried eggshell membrane powder; (2) Preparation of electrospinning solution: The dried eggshell membrane powder and PEO were directly added into 30 mL of aqueous solution to prepare the eggshell membrane / PEO blend, i.e., the electrospinning solution; The mass ratio of PEO to dried eggshell membrane powder was 1:2, the concentration of PEO in the electrospinning solution was 400,000 g / mol, and the concentration of eggshell membrane / PEO in the electrospinning solution was 15 wt %; (3) Preparation of electrospinning fiber membrane: During the electrospinning process, the electrospinning solution prepared in the previous step was filled into a 10 mL syringe equipped with a 19-gauge steel needle with an inner diameter of 0.5 mm; after removing the bubbles in the syringe, the syringe was fixed on a syringe pump; the steel needle was connected to a TCM6002 high-voltage DC power supply through a tungsten electrode; a 20 kV potential was applied to the tip of the injection needle; the distance between the steel needle and the collecting roller was 10 cm; the applied spinning rate was 0.5 mL / h; the collecting roller rotated at a speed of 400 rpm; the spinning temperature was 35 ° C, and the spinning humidity was 65%; after electrospinning, the aluminum foil with the forming pad was immediately taken out from the collecting roller and placed in a hood for 24 hours to remove residual organic solvents and moisture; a nanofiber membrane was obtained; (4) Preparation of flexible piezoelectric sensors: The nanofiber membrane obtained in the previous step was encapsulated using 10 mL of PDMS and 1 mL of curing agent in a ratio of 10:1, and dried in a vacuum drying oven at 100° C. for 30 minutes to obtain a flexible piezoelectric sensor.

2. Application of the flexible piezoelectric sensor prepared by the method for improving the piezoelectric properties of regenerated eggshell membrane according to claim 1 in the fields of smart wearable devices, health monitoring and energy storage.

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