Composite fiber membrane based on sea urchin-shaped pollen carbon, preparation method and application

Abstract

The invention provides a composite fiber membrane based on sea urchin-shaped pollen carbon, a preparation method and application. The preparation method of the composite fiber membrane comprises the following steps: degreasing pollen, and carbonizing at high temperature to prepare the pollen carbon with a sea urchin-shaped microstructure; adding the pollen carbon and the elastomer which serve as solutes into a mixed solvent formed by a low-boiling-point solvent and a high-boiling-point solvent to obtain an electrostatic spinning precursor; and performing electrostatic spinning on the electrostatic spinning precursor to obtain the composite fiber membrane. The composite fiber membrane is used as a pressure sensitive layer to prepare the flexible pressure sensor, and the flexible pressure sensor has a double microstructure of a conductive filler and a porous elastomer, so that the problem that an existing microstructure pressure sensor cannot have high flexibility, high sensitivity and a wide linear range at the same time is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a composite fiber membrane based on urchin-like pollen carbon, a preparation method and application. BACKGROUND

[0002] Flexible pressure sensor is one of the core research directions in the field of flexible electronics in recent years, and its technical development is derived from the demand for breaking through the limitations of traditional rigid sensors. Under the promotion of industrial 4.0 and Internet of Things technology, there is an urgent need for flexible sensing technology with curve adaptation capability in the fields of medical health monitoring, intelligent robots, wearable devices, etc. Although traditional piezoresistive / capacitive sensors based on silicon materials have high precision characteristics, their rigid structure cannot meet the application requirements of complex curve fitting, repeated bending and large deformation scenes, which prompts researchers to develop new sensing materials with mechanical flexibility and ductility.

[0003] The key technical innovation mainly reflects in two dimensions of material system and structure design: in the material level, breakthroughs have been made in new functional materials such as conductive polymers (such as PEDOT:PSS), nano-conductive materials (nano-silver, carbon nanotubes, graphene), and liquid metals (gallium-based alloys), which realize the sensitive conversion of pressure-electric signal through the construction of conductive network microstructure; in the aspect of structure design, researchers have developed micro-pyramid array, porous elastomer, layered wrinkle and other microstructures, and utilized the change of contact area to enhance the pressure sensitivity.

[0004] Although the microstructure pressure sensors reported in the past have good performance in some aspects, for example, the sensor with porous elastomer structure has good sensitivity, but because the deformation and pressure are not completely linear, the overall sensor response to pressure will lose a certain linear range; while the sensor with pyramid microstructure has high linearity of pressure response, but the limited contact area change range limits its sensitivity. These sensors are difficult to have high flexibility, high sensitivity and wide linear detection range, and their performance often cannot meet people's needs. SUMMARY

[0005] In view of the above prior art, at least one of the technical problems is solved, and the application embodiment proposes a composite fiber membrane based on urchin-like pollen carbon, a preparation method and application. The composite fiber membrane is prepared based on urchin-like pollen carbon, and the composite fiber membrane is used as a pressure sensitive layer to prepare a flexible pressure sensor. The flexible pressure sensor has a dual microstructure of conductive filler and porous elastomer, so as to solve the problem that the existing microstructure pressure sensor cannot have high flexibility, high sensitivity and wide linear range.

[0006] According to the first aspect of the application, a preparation method of a composite fiber membrane based on urchin-like pollen carbon is provided, including the following steps:

[0007] The pollen is defatted and then high-temperature carbonized to prepare pollen carbon with urchin-like microstructure;

[0008] The pollen carbon and the elastomer are added together as solutes into a mixed solvent formed by a low-boiling-point solvent and a high-boiling-point solvent to obtain an electrospinning precursor; wherein the mass percentage content of the pollen carbon is 5-30% based on the solutes; the mass concentration of the solutes is 10-30% based on the electrospinning precursor; and the mass percentage of the low-boiling-point solvent is 10-50% based on the mixed solvent;

[0009] The electrospinning precursor is electrospun to obtain a composite fiber membrane.

[0010] In some embodiments, the pollen includes at least one of sunflower pollen, watercress pollen, or yellow autumn flower pollen;

[0011] And / or, the pollen is treated with an organic solvent for 1-3 times, and after each time of 2-12 hours, a pollen precipitate is obtained; the pollen precipitate is high-temperature treated at 500-1000°C for 1-5 hours in an inert atmosphere to obtain pollen carbon;

[0012] And / or, the organic solvent includes methanol, ethanol, diethyl ether, or acetone.

[0013] In some embodiments, the elastomer includes thermoplastic polyurethane, polyolefin elastomer, or styrene-butadiene block copolymer;

[0014] And / or, the low-boiling-point solvent includes tetrahydrofuran, acetone, cyclohexane, or diethyl ether.

[0015] And / or, the high-boiling-point solvent includes N,N-dimethylformamide, N-methylpyrrolidone, N,N-dimethylacetamide, or dimethyl sulfoxide.

[0016] In some embodiments, the electrospinning is performed in an electrospinning machine, and the parameters are as follows: the electric field strength is 1-1.5 kV / cm, the inner diameter of the needle is 0.2-0.6 mm, and the flow rate of the electrospinning precursor is 0.5-2 mL / h.

[0017] And / or, the distance between the needle tip and the receiving drum is 10-15 cm, the rotating speed of the drum is 200-400 rpm, and the spinning time is 1-6 h.

[0018] In some embodiments, the thickness of the composite fiber membrane is 10 μm-100 μm.

[0019] According to a second aspect of the present application, a composite fiber membrane based on urchin-like pollen carbon is provided, which is prepared by the preparation method described in any of the above embodiments.

[0020] In some embodiments, the electrospinning precursor comprises, by mass percentage, 0.5-9% of pollen carbon with urchin-like microstructure, 7-28.5% of elastomer, 7-45% of low-boiling-point solvent, and 35-81% of high-boiling-point solvent.

[0021] According to a third aspect of the present application, there is provided a use of the composite fiber membrane described in any of the above embodiments in preparing a flexible sensor.

[0022] According to a fourth aspect of the present application, there is provided a flexible sensor comprising the composite fiber membrane described in any of the above embodiments, an electrode layer arranged on both sides of the composite fiber membrane in the thickness direction, and a packaging layer arranged on the side of the electrode layer away from the composite fiber membrane.

[0023] In some embodiments, the packaging layer has a thickness of 10-30 μm; it is a single-sided adhesive ultra-thin adhesive tape; the material of the ultra-thin adhesive tape is polyethylene terephthalate, polyimide, or polytetrafluoroethylene;

[0024] The electrode layer has a thickness of 10-30 μm; it is an ultra-thin conductive cloth; the material of the ultra-thin conductive cloth is nickel cloth, copper cloth, or carbon cloth;

[0025] The composite fiber membrane has a thickness of 10-100 μm.

[0026] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0027] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings, wherein:

[0028] Figure 1 A schematic diagram of the preparation process of the composite fiber membrane based on urchin-like pollen carbon provided by an embodiment of the present application;

[0029] Figure 2 SEM images of urchin-like pollen, pollen carbon, and composite fiber membrane provided by another embodiment of the present application, with a scale bar of 10 microns;

[0030] Figure 3 A schematic diagram of the structure of a flexible pressure sensor provided by an embodiment of the present application;

[0031] Figure 4 A schematic diagram of the compression of the composite fiber membrane applied to a flexible pressure sensor under different pressures provided by an embodiment of the present application;

[0032] Figure 5An electrical signal test curve of the flexible pressure sensor provided by an embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to enable persons skilled in the art to better understand the schemes of the present application, the technical schemes in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments, and are not intended to limit the scope of the present application. In addition, in the following description, the description of the well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts should fall within the scope of protection of the present application.

[0034] The structural schematic diagrams according to the embodiments disclosed in the present application are shown in the drawings. These diagrams are not drawn to scale, in which some details are enlarged for the purpose of clear expression, and some details can be omitted. The shapes of various regions, layers and their relative size and positional relationship shown in the diagrams are only exemplary, and in actuality, there can be deviations due to manufacturing tolerances or technical limitations, and the regions / layers with different shapes, sizes and relative positions can be additionally designed by those skilled in the art according to actual needs.

[0035] The embodiments of the present application will be described below with reference to the accompanying drawings Figure 1 The embodiments of the present application are described below, in particular, a preparation method of a composite fiber membrane based on urchin-shaped pollen carbon is proposed according to the first aspect of the present application, which comprises the following steps:

[0036] S1: preparing pollen carbon with urchin-shaped microstructure by defatting and high-temperature carbonization of pollen;

[0037] S2: adding the pollen carbon and the elastomer together as solutes into a mixed solvent formed by a low-boiling-point solvent and a high-boiling-point solvent to obtain an electrospinning precursor; wherein the mass percentage content of the pollen carbon is 5-30% based on the solutes; the mass concentration of the solutes is 10-30% based on the electrospinning precursor; and the mass percentage of the low-boiling-point solvent is 10-50% based on the mixed solvent;

[0038] S3: obtaining a composite fiber membrane by electrospinning the electrospinning precursor.

[0039] In S1, the pollen is defatted, wherein the pollen is urchin-shaped pollen, including at least one of sunflower pollen, watercress pollen or yellow autumn pollen, wherein the sunflower pollen is urchin-shaped pollen, and the SEM diagram of the sunflower pollen is as shown in Figure 2The overall diameter of the pollen is 20-30 microns, and the main body is a sphere with a diameter of about 20 microns, and the surface is scattered with spikes with a length of about 5 microns. The pollen is defatted by using an organic solvent, which includes methanol, ethanol, diethyl ether or acetone. The defatting process is as follows: the pollen is added to the organic solvent, stirred and treated for 2-12 hours, and treated 1-3 times. The treated system is filtered, and the filtrate is centrifuged to obtain a pollen precipitate. The pollen precipitate is washed and stirred with an organic solvent, centrifuged and dried.

[0040] The pollen is added to the organic solvent, stirred and treated for 2-12 hours, and treated 1-3 times. The treated system is filtered with a filter screen, such as a 200-mesh filter screen. The filtrate is treated in a centrifuge at 3000 rpm for 10 minutes, leaving a pollen precipitate. The precipitate is washed and stirred with 100 milliliters of organic solvent, centrifuged and dried in a 60°C oven for 12 hours to achieve pollen defatting and obtain a pollen precipitate.

[0041] In this embodiment, the pollen precipitate is further carbonized at a high temperature. The process includes treating the pollen precipitate at a high temperature of 500-1000°C for 1-5 hours in an inert atmosphere, which includes an argon atmosphere or a nitrogen atmosphere, to obtain pollen carbon with a sea urchin-like microstructure. The SEM image of the pollen carbon with a sea urchin-like microstructure is shown in Figure 2 As shown, the pollen carbon maintains the sea urchin-like structure of the pollen after carbonization, and the overall diameter is 20-30 microns, and the main body is a sphere with a diameter of about 20 microns, and the surface is scattered with spikes with a length of about 5 microns. In an example, the above pollen precipitate is placed in a tube furnace, treated at a temperature of 800°C for 2 hours in an argon atmosphere, and naturally cooled to obtain pollen carbon with a sea urchin-like microstructure.

[0042] In S2, the pollen carbon with a sea urchin-like microstructure and the elastomer are mixed as a common solute. The elastomer includes a thermoplastic polyurethane, a polyolefin elastomer or a styrene-butadiene block copolymer. The mass percentage of the pollen carbon is 5-30% based on the solute. In an example, the mass percentage of the pollen carbon is 5%, 10%, 15%, 20%, 25%, 26%, 28%, 30% or the like. The content of the pollen carbon directly affects the resistance change rate of the pressure sensor, thereby affecting the sensitivity and range of the device. In some embodiments, when the mass percentage of the pollen carbon is too low, such as less than 5%, a continuous conductive path cannot be formed, and the resistance value of the device under different pressures is large, the change rate is low, resulting in low sensitivity and narrow range. In some embodiments, when the mass percentage of the pollen carbon is too high, such as higher than 30%, a continuous conductive path is formed in the initial state, and the resistance change rate of the device under different pressures is also low, resulting in low sensitivity and narrow range.

[0043] In the process, the urchin-like microstructure pollen carbon and elastomer are mixed as a common solute added to the mixed solvent at 60°C for 6 hours, the mass concentration of the solute is 10-30%, and the electrospinning precursor is obtained, wherein the mixed solvent includes a low boiling point solvent and a high boiling point solvent, wherein the low boiling point solvent includes tetrahydrofuran, acetone, cyclohexane or diethyl ether; the high boiling point solvent includes N,N-dimethylformamide, N-methyl pyrrolidone, N,N-dimethylacetamide or dimethyl sulfoxide, and the mass percentage of the low boiling point solvent is 10-50% based on the mixed solvent.

[0044] The mass percentage of the low boiling point solvent is 10%, 15%, 20%, 25%, 26%, 28%, 30%, 40%, 50% and the like, and the low boiling point solvent volatilizes quickly in the electrospinning process, so that the polymer is precipitated and formed, and the nanofiber electrospinning membrane is conveniently prepared. In some embodiments, when the mass percentage of the low boiling point solvent is too low, such as less than 10%, the polymer precipitates and forms slowly, and the nanofiber morphology in the membrane is less. In some embodiments, when the mass percentage of the low boiling point solvent is too high, such as more than 50%, the polymer precipitates quickly, and the needle is easily blocked, which is not conducive to the stretching of the polymer into a fiber shape under a high-voltage electric field.

[0045] The mass concentration of the solute is 10%, 15%, 20%, 25%, 26%, 28%, 30% and the like, and the content of the solute mainly affects the viscosity of the electrospinning precursor. In some embodiments, when the mass percentage of the solute is too low, such as less than 10%, the viscosity is low, and the liquid has strong fluidity, which directly drips at the outlet of the needle and is not easy to stretch into a fiber shape in a high-voltage electric field. In some embodiments, when the mass percentage of the solute is too high, such as more than 30%, on the one hand, the liquid has poor fluidity due to high viscosity, and is not easy to extrude from the needle; on the other hand, the solubility of the polymer in the solvent is limited, and the content is too high to be fully dissolved.

[0046] In S3, the electrospinning precursor is electrospun to obtain a composite fiber membrane, and the SEM image of the composite fiber membrane is as shown in Figure 2 The electrospinning fiber membrane is composed of a three-dimensional nanofiber network, and the pollen carbon is uniformly embedded in the network of the fiber membrane, wherein there is a certain spacing between the pollen carbon, about 2-5 microns. The electrospinning is carried out in an electrospinning machine, and the parameters are as follows: the electric field strength is 1-1.5 kV / cm, the inner diameter of the needle is 0.2-0.6 mm, the flow rate of the electrospinning precursor is 0.5-2 mL / h; the distance between the needle tip and the receiving drum is 10-15 cm, the rotating speed of the drum is 200-400 rpm, and the spinning time is 1-6 h.

[0047] For example, an electrospinning precursor is added to a syringe, and a composite fiber membrane is prepared in an electrospinning machine, wherein the electric field strength is 1-1.5 kV / cm, the inner diameter of the needle is 0.2-0.6 mm, and the flow rate of the electrospinning precursor is 0.5-2 mL / h; the distance between the needle tip and the receiving roller is 10-15 cm, the roller speed is 200-400 rpm, and the spinning time is 1-6 h. The obtained composite fiber membrane can be dried, wherein the drying can be carried out in an oven at 60°C for 12 hours, and the thickness of the composite fiber membrane is 10 μm to 100 μm.

[0048] According to the second aspect of the present application, a composite fiber membrane based on sea urchin-shaped pollen carbon is proposed, which is prepared using the preparation method in any of the above embodiments. Based on the electrospinning precursor, it includes 0.5-9% pollen carbon with a sea urchin-shaped microstructure, 7-28.5% elastomer, 7-45% low boiling point solvent and 35-81% high boiling point solvent in terms of mass percentage. The example is based on the electrospinning precursor, and in terms of mass percentage, it includes 4% pollen carbon with a sea urchin-shaped microstructure, 16% elastomer, 26.7% low boiling point solvent and 53.3% high boiling point solvent.

[0049] According to a third aspect of the present application, it is proposed that the composite fiber membrane in any of the above embodiments is used in the preparation of a flexible sensor.

[0050] According to the fourth aspect of the present application, a flexible sensor is proposed. Figure 3 As shown, it includes the composite fiber membrane in any of the above embodiments, electrode layers arranged on both sides of the composite fiber membrane in the thickness direction, and an encapsulation layer arranged on the side of the electrode layer away from the composite fiber membrane.

[0051] For example, Figure 3 Taking the vertical direction of the composite fiber membrane as an example, the composite fiber membrane has a thickness of 10 μm to 100 μm and has an upper surface and a lower surface in the vertical direction. Electrode layers are disposed above the upper surface and below the lower surface of the composite fiber membrane, respectively. The electrode layers are 10 μm to 30 μm thick and are made of ultra-thin conductive fabric, such as nickel fabric, copper fabric, or carbon fabric. An encapsulation layer is applied to the electrode layers on both sides of the composite fiber membrane. The encapsulation layer is 10 μm to 30 μm thick and is made of an ultra-thin tape with adhesive on one side, such as polyethylene terephthalate, polyimide, or polytetrafluoroethylene.

[0052] The composite fiber membrane in this embodiment can be used as the sensitive layer of the flexible sensor. The schematic diagram of its compression under different pressures is shown in FIG. Figure 4As shown, in the initial stage of compression of the composite fiber membrane, there is a certain distance between the carbon spheres in the composite fiber membrane, and no conductive path is formed, at which time the resistance value is large. After being lightly touched, the composite fiber membrane deforms under pressure, and the spikes of some carbon spheres contact each other, forming a long conductive path, at which time the resistance value is slightly reduced; when the spikes act on the composite fiber membrane, a local short-path conductive path is formed in the vertical direction, at which time the resistance value is suddenly reduced, which can be used as a pain sensation; when the flexible sensor bears heavy pressure, the carbon spheres in the composite fiber membrane are in close contact, forming a complete conductive path, and the resistance value is suddenly reduced.

[0053] The flexible sensor obtained by the embodiment is used for electrical signal test, and an electrical signal test curve as shown in the figure is obtained. Figure 5 The current change rate under different pressures is tested, and the sensitivity is 70.2 kPa -1 when the pressure is small (0-20 kPa), the sensitivity is 105.6 kPa -1 when the pressure increases to 20-100 kPa, the sensitivity is 58.2 kPa -1 in the pressure range of 100-500 kPa, and the sensitivity is 21.1 kPa -1 when the pressure continues to increase to 500-3000 kPa. Therefore, the sea urchin-shaped microstructure pollen carbon is used as the conductive filler, and the porous fiber membrane is prepared by using the electrospinning technology, to obtain the composite fiber membrane, the composite fiber membrane has the double microstructure of the conductive filler and the porous elastomer, which is applied to the preparation process of the flexible pressure sensor, expands the linear range of the flexible pressure sensor and improves the detection sensitivity, so as to solve the problem that the existing microstructure pressure sensor cannot have high flexibility, high sensitivity and wide linear range.

[0054] In order to further understand the present application, the scheme of the present application will be further described in combination with the embodiments. Those skilled in the art will understand that only some embodiments are described in the present application, and any other suitable specific embodiments are within the scope of the present application.

[0055] Embodiment 1

[0056] The present embodiment proposes a preparation method of a microstructure flexible pressure sensor based on sea urchin-shaped pollen carbon, wherein the electrospinning precursor of the composite fiber membrane includes the following components by mass percentage: sunflower pollen carbon 4%; polyurethane 16%; tetrahydrofuran 26.7%; N,N-dimethylformamide 53.3%.

[0057] The specific preparation steps are as follows: 10 grams of sunflower pollen particles are added to 100 milliliters of methanol, stirred for 4 hours, filtered with a 200-mesh filter screen, and the filtrate is treated in a centrifuge at 3000 rpm for 10 minutes, leaving the pollen sediment. The sediment is washed with 100 milliliters of methanol again, and after centrifugal sedimentation, it is dried in an oven at 60°C for 12 hours. The above-mentioned pollen is placed in a tube furnace and treated at a temperature of 800°C for 2 hours under an argon atmosphere, and after natural cooling, pollen carbon is obtained. The electrospinning precursor preparation takes 0.4 grams of pollen carbon, 1.6 grams of polyurethane, and adds them to a mixed solvent of 2.67 grams of tetrahydrofuran and 5.33 grams of N,N-dimethylformamide, and stirs at 60°C for 6 hours. The precursor is added to a 10-milliliter syringe, and a composite fiber membrane is prepared in an electrospinning machine, with an electric field intensity of 1.2 kV / cm, a needle inner diameter of 0.4 mm, a precursor flow rate of 1 mL / h, a needle tip to receiving drum distance of 12 cm, a drum rotating speed of 250 rpm, and a spinning time of 4 hours. The obtained fiber membrane is dried in an oven at 60°C for 12 hours. The thickness of the composite fiber membrane is 30 microns. A polyethylene terephthalate tape with a thickness of 20 microns, a nickel cloth with a thickness of 20 microns, a composite fiber membrane, a nickel cloth with a thickness of 20 microns, and a polyethylene terephthalate tape with a thickness of 20 microns are stacked in order, and after leading out the lead wire, a flexible pressure sensor is obtained.

[0058] The change in current of the flexible pressure sensor under pressure is tested with a digital multimeter, with a voltage setting of 100 mV.

[0059] Example 2

[0060] This example proposes a preparation method of a microstructure flexible pressure sensor based on sea urchin-shaped pollen carbon, wherein the electrospinning precursor of the composite fiber membrane film includes the following components by mass percentage: 0.5% of water spinach pollen carbon; 9.5% of polyolefin elastomer; 9% of acetone; and 81% of N-methyl pyrrolidone.

[0061] The specific preparation steps are as follows: 10 grams of watercress flower powder particles are added to 100 milliliters of ethanol, stirred for 12 hours, filtered with a 200-mesh filter screen, and the filtrate is treated in a centrifuge at 3000 rpm for 10 minutes. The precipitate is dried in an oven at 60°C for 12 hours. The above-mentioned flower powder is placed in a tube furnace and treated at a temperature of 500°C for 5 hours under a nitrogen atmosphere, and after natural cooling, the flower powder carbon is obtained. The electrospinning precursor preparation is as follows: 0.05 grams of flower powder carbon, 0.95 grams of polyolefin elastomer, and 0.9 grams of acetone and 8.1 grams of N-methyl pyrrolidone mixed solvent are added, and stirred at 60°C for 6 hours. The precursor is added to a 10-milliliter syringe, and a composite fiber membrane is prepared in an electrospinning machine, wherein the electric field strength is 1 kV / cm, the needle inner diameter is 0.2 mm, the precursor flow rate is 0.5 mL / h, the needle tip distance from the receiving drum is 10 cm, the drum rotation speed is 200 rpm, and the spinning time is 1 hour. The obtained fiber membrane is dried in an oven at 60°C for 12 hours, and the thickness of the composite fiber membrane is 10 μm.

[0062] A flexible pressure sensor is obtained by laminating a polyimide tape with a thickness of 10 μm, a copper cloth with a thickness of 10 μm, a composite fiber membrane, a copper cloth with a thickness of 10 μm, and a polyimide tape with a thickness of 10 μm in order, and leading out a lead wire. The change in current of the flexible pressure sensor under pressure is tested by a digital multimeter, wherein the voltage is set to 100 mV.

[0063] Example 3

[0064] The present embodiment proposes a preparation method of a microstructure flexible pressure sensor based on sea urchin-shaped flower powder carbon, wherein the electrospinning precursor of the composite fiber membrane film comprises the following components by mass percentage: 9% of watercress flower powder carbon; 21% of styrene-butadiene block copolymer; 35% of cyclohexane; and 35% of N,N-dimethylacetamide.

[0065] The specific preparation steps are as follows: 10 grams of watercress flower powder particles are added to 100 milliliters of ether, stirred for 2 hours, filtered with a 200-mesh filter screen, and the filtrate is treated in a centrifuge at 3000 rpm for 10 minutes, leaving the flower powder sediment. The sediment is washed with 100 milliliters of ether for 2 hours, and finally the sediment is dried in an oven at 60°C for 12 hours. The above-mentioned flower powder is placed in a tube furnace and treated at a temperature of 1000°C for 1 hour under a nitrogen atmosphere, and after natural cooling, the flower powder carbon is obtained. The electrospinning precursor preparation is as follows: 1.8 grams of flower powder carbon, 4.2 grams of styrene-butadiene block copolymer, and 7 grams of a mixed solvent of cyclohexane and N,N-dimethylacetamide are added to 7 grams of N,N-dimethylacetamide, and stirred at 60°C for 6 hours. The precursor is added to a 20-milliliter syringe, and a composite fiber membrane is prepared in an electrospinning machine, with an electric field strength of 1.5 kV / cm, a needle inner diameter of 0.6 mm, a precursor flow rate of 2 mL / h, a needle tip to receiving drum distance of 15 cm, a drum rotating speed of 400 rpm, and a spinning time of 6 hours. The obtained fiber membrane is dried in an oven at 60°C for 12 hours, and the composite fiber membrane thickness is 100 μm.

[0066] A flexible pressure sensor is obtained by stacking a polytetrafluoroethylene tape with a thickness of 30 μm, a carbon cloth with a thickness of 30 μm, a composite fiber membrane, a carbon cloth with a thickness of 30 μm, and a polytetrafluoroethylene tape with a thickness of 30 μm in order, and leading out a lead wire. The change in current of the flexible pressure sensor under pressure is tested with a digital multimeter, with a voltage setting of 100 mV.

[0067] Example 4

[0068] The present embodiment proposes a preparation method of a microstructure flexible pressure sensor based on sea urchin-shaped flower powder carbon, wherein the electrospinning precursor of the composite fiber membrane film comprises the following components by mass percentage: 4% of sunflower pollen carbon; 16% of polyurethane; 26.7% of ether; and 53.3% of dimethyl sulfoxide.

[0069] Specific preparation steps are as follows: 10 grams of sunflower pollen particles are added to 100 milliliters of acetone, stirred for 6 hours, filtered with a 200 mesh filter, and the filtrate is treated in a centrifuge at 3000 rpm for 10 minutes, leaving the pollen sediment. The sediment is washed with 100 milliliters of methanol again, and after centrifugal sedimentation, it is dried in an oven at 60°C for 12 hours. The above-mentioned pollen is placed in a tube furnace, treated at a temperature of 600°C for 3 hours under an argon atmosphere, and after natural cooling, pollen carbon is obtained. The electrospinning precursor is prepared by taking 0.4 grams of pollen carbon, 1.6 grams of polyurethane, and adding them to a mixed solvent of 2.67 grams of diethyl ether and 5.33 grams of dimethyl sulfoxide, and stirring at 60°C for 6 hours. The precursor is added to a 10 milliliter syringe, and a composite fiber membrane is prepared in an electrospinning machine, where the electric field strength is 1.2 kV / cm, the needle inner diameter is 0.4 mm, the precursor flow rate is 1 mL / h, the needle tip distance from the receiving drum is 12 cm, the drum rotation speed is 250 rpm, and the spinning time is 5 hours. The obtained fiber membrane is dried in an oven at 60°C for 12 hours. The thickness of the composite fiber membrane is 40 μm.

[0070] A polyethylene terephthalate tape with a thickness of 20 μm, a nickel cloth with a thickness of 20 μm, a composite fiber membrane, a nickel cloth with a thickness of 20 μm, and a polyethylene terephthalate tape with a thickness of 20 μm are sequentially laminated, and a flexible pressure sensor is obtained after leading out the lead wire. The change in current of the flexible pressure sensor under pressure is tested by a digital multimeter, where the voltage is set to 100 mV.

[0071] Comparative Example 1

[0072] This comparative example proposes a preparation method of a microstructure flexible pressure sensor based on sea urchin-shaped pollen carbon, where the pollen carbon and elastomer composite membrane are prepared by a scraping method, and the precursor includes the following components by mass percentage: sunflower pollen carbon is 4%; polyurethane is 16%; diethyl ether is 26.7%; dimethyl sulfoxide is 53.3%.

[0073] Specific preparation steps are as follows: 10 grams of sunflower pollen particles are added to 100 milliliters of acetone, stirred for 6 hours, filtered with a 200 mesh filter, and the filtrate is treated in a centrifuge at 3000 rpm for 10 minutes, leaving the pollen sediment. The sediment is washed with 100 milliliters of methanol again, and after centrifugal sedimentation, it is dried in an oven at 60°C for 12 hours. The above-mentioned pollen is placed in a tube furnace, treated at a temperature of 600°C for 3 hours under an argon atmosphere, and after natural cooling, pollen carbon is obtained. The electrospinning precursor is prepared by taking 0.4 grams of pollen carbon, 1.6 grams of polyurethane, and adding them to a mixed solvent of 2.67 grams of diethyl ether and 5.33 grams of dimethyl sulfoxide, and stirring at 60°C for 6 hours. The precursor is added to a 10 milliliter syringe, and a composite fiber membrane is prepared in an electrospinning machine, where the electric field strength is 1.2 kV / cm, the needle inner diameter is 0.4 mm, the precursor flow rate is 1 mL / h, the needle tip distance from the receiving drum is 12 cm, the drum rotation speed is 250 rpm, and the spinning time is 5 hours. The obtained fiber membrane is dried in an oven at 60°C for 12 hours. The thickness of the composite fiber membrane is 40 μm.

[0074] A flexible pressure sensor was obtained by stacking a polyethylene terephthalate tape with a thickness of 20 pm, a nickel cloth with a thickness of 20 pm, the composite film, a nickel cloth with a thickness of 20 pm, and a polyethylene terephthalate tape with a thickness of 20 pm in sequence, and leading out a lead wire. The flexible pressure sensor was tested by a digital multimeter. The current change under pressure was tested, wherein the voltage was set to 100 mV.

[0075] Comparative Example 2

[0076] The present comparative example proposes a preparation method of a microstructure flexible pressure sensor, wherein the electrospinning precursor of the circular carbon microspheres and elastomer composite fiber film includes the following components by mass percentage: 4% of Ketjen black; 16% of polyurethane; 26.7% of diethyl ether; and 53.3% of dimethyl sulfoxide.

[0077] The specific preparation steps are as follows: electrospinning precursor preparation, 0.4 g of Ketjen black and 1.6 g of polyurethane are added into a mixed solvent of 2.67 g of diethyl ether and 5.33 g of dimethyl sulfoxide, and stirred at 60°C for 6 hours. The precursor is added into a 10 mL syringe, and a composite fiber film is prepared in an electrospinning machine, wherein the electric field intensity is 1.2 kV / cm, the inner diameter of the needle is 0.4 mm, the flow rate of the precursor is 1 mL / h, the distance between the needle tip and the receiving drum is 12 cm, the rotating speed of the drum is 250 rpm, and the spinning time is 5 hours. The obtained fiber film is dried in an oven at 60°C for 12 hours, and the thickness of the composite fiber film is 40 pm.

[0078] A flexible pressure sensor was obtained by stacking a polyethylene terephthalate tape with a thickness of 20 pm, a nickel cloth with a thickness of 20 pm, the composite fiber film, a nickel cloth with a thickness of 20 pm, and a polyethylene terephthalate tape with a thickness of 20 pm in sequence, and leading out a lead wire. The flexible pressure sensor was tested by a digital multimeter. The current change under pressure was tested, wherein the voltage was set to 100 mV.

[0079] Experimental Example

[0080] The range and sensitivity of the flexible pressure sensor obtained in the above examples and comparative examples were tested, wherein the range of the flexible pressure sensor was detected by the following method: a 100 mV voltage was applied to the electrodes at both ends of the flexible pressure sensor, a digital multimeter was used to measure the current value, the flexible pressure sensor was placed on the pressure plate of a pressure machine, and the current value under different pressure loads was recorded.

[0081] The sensitivity of the flexible pressure sensor was calculated according to the following formula: the calculation formula of the sensitivity S is S=(AI / I0) / AP, AI is the current change value, I0 is the current value under no pressure load, and AP is the pressure change value (kPa), and the results are shown in Table 1.

[0082] Table 1 Range and sensitivity of different flexible pressure sensors

[0083]

[0084] As can be seen from Table 1, compared with the composite film with only urchin-like conductive filler obtained by blade coating in Comparative Example 1 and the composite fiber film with round carbon sphere obtained by electrospinning in Comparative Example 2, the sensitive layer of the flexible pressure sensor in Example 1-4 is a composite fiber film with double microstructure of conductive filler and matrix, thus showing significant advantages in range and sensitivity indicators. Changing the electrospinning conditions has a certain influence on the thickness of the composite fiber film. When the sensitive layer is too thin, although the sensitivity is higher, the range is smaller, and when the sensitive layer is too thick, although the range is wider, the sensitivity is obviously reduced.

[0085] In summary, the microstructure flexible pressure sensor provided by the embodiments of the present application adopts urchin-like pollen carbon as the conductive filler and uses the electrospinning technology to prepare the porous fiber film as the matrix, thereby obtaining the composite fiber film with double microstructure as the sensitive layer, which expands the linear range of the flexible pressure sensor and improves the detection sensitivity.

[0086] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0087] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0088] Although the embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for preparing a composite fiber membrane based on sea urchin-like pollen carbon, characterized in that: The following steps are involved: The pollen is defatted and then carbonized at high temperature to prepare pollen carbon with sea urchin-like microstructure. The pollen carbon and the elastomer are added together as solutes into a mixed solvent formed by a low-boiling-point solvent and a high-boiling-point solvent to obtain an electrospinning precursor; wherein the mass percentage of the pollen carbon is 5-30% based on the solute; the mass concentration of the solute is 10-30% based on the electrospinning precursor; and the mass percentage of the low-boiling-point solvent is 10-50% based on the mixed solvent; The electrospinning precursor is subjected to electrospinning to obtain a composite fiber membrane.

2. The preparation method according to claim 1, characterized in that The pollen includes at least one of sunflower pollen, mizuna pollen or yellow safflower pollen; and / or, the pollen is treated with an organic solvent 1-3 times, each time for 2-12 hours to obtain pollen sediment; the pollen sediment is treated at a high temperature of 500-1000° C. in an inert atmosphere for 1-5 hours to obtain pollen carbon; And / or, the organic solvent includes methanol, ethanol, ether or acetone.

3. The preparation method according to claim 1, characterized in that The elastomer comprises thermoplastic polyurethane, polyolefin elastomer or styrene-butadiene block copolymer; and / or, the low boiling point solvent comprises tetrahydrofuran, acetone, cyclohexane or diethyl ether; And / or, the high boiling point solvent includes N,N-dimethylformamide, N,-methylpyrrolidone, N,N-dimethylacetamide or dimethyl sulfoxide.

4. The preparation method according to claim 1, characterized in that Electrospinning was performed in an electrospinning machine with the following parameters: electric field strength of 1-1.5 kV / cm, needle inner diameter of 0.2-0.6 mm, and electrospinning precursor flow rate of 0.5-2 mL / h; And / or, the distance between the needle tip and the receiving roller is 10-15 cm, the roller rotation speed is 200-400 rpm, and the spinning time is 1-6 h.

5. The preparation method according to any one of claims 1 to 4, characterized in that The thickness of the composite fiber membrane is 10 μm to 100 μm.

6. A composite fiber membrane based on sea urchin-like pollen carbon, characterized in that: The invention discloses a novel nanostructured carbonyl phosphate ...

7. The composite fiber membrane according to claim 6, characterized in that Based on the electrospinning precursor, the electrospinning precursor comprises, by mass percentage, 0.5-9% of pollen carbon with sea urchin-like microstructure, 7-28.5% of elastomer, 7-45% of low-boiling-point solvent and 35-81% of high-boiling-point solvent.

8. Use of the composite fiber membrane according to claim 6 or 7 in the preparation of flexible sensors.

9. A flexible sensor, characterized in that: The invention comprises the composite fiber membrane as claimed in claim 6 or 7, electrode layers arranged on both sides of the composite fiber membrane in the thickness direction, and an encapsulation layer arranged on the side of the electrode layer away from the composite fiber membrane.

10. The flexible sensor according to claim 9, characterized in that The thickness of the encapsulation layer is 10 μm to 30 μm; it is an ultra-thin tape with adhesive on one side; the material of the ultra-thin tape is polyethylene terephthalate, polyimide or polytetrafluoroethylene; The thickness of the electrode layer is 10 μm to 30 μm; it is an ultra-thin conductive cloth; the material of the ultra-thin conductive cloth is nickel cloth, copper cloth and carbon cloth; The thickness of the composite fiber membrane is 10 μm to 100 μm.

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