阅读说明：本技术 一种基于复合微纳米纤维的柔性力敏传感器及其制备方法 (Flexible force-sensitive sensor based on composite micro-nano fibers and preparation method thereof ) 是由 赵更锐 王宏刚 陈生圣 任俊芳 高贵 王金清 杨生荣 于 2020-06-05 设计创作，主要内容包括：本发明涉及一种基于复合微纳米纤维的柔性力敏传感器,该传感器包括外壳及置于所述外壳内微米级图案阵列基底和导电离子凝胶复合微纳米纤维。所述微米级图案阵列基底上设有呈微凸体的光刻图案；所述导电离子凝胶复合微纳米纤维附着在所述微米级图案阵列基底上,该导电离子凝胶复合微纳米纤维连有外接导线。同时本发明还公开了该传感器的制备方法。本发明利用了复合纤维微形变与微接触产生的压阻机制,实现柔性传感器法向压力和表面切向力的传感,可应用于表面物体接触时产生的摩擦力传感,对摩擦副之间摩擦力变化与摩擦状态的监测传感具有重大应用价值。(The invention relates to a flexible force-sensitive sensor based on composite micro-nanofibers, which comprises a shell, and a micron-sized pattern array substrate and conductive ionic gel composite micro-nanofibers which are arranged in the shell. Photoetching patterns in the form of micro-convex bodies are arranged on the micron pattern array substrate; the conductive ionic gel composite micro-nano fiber is attached to the micron-sized pattern array substrate and is connected with an external lead. Meanwhile, the invention also discloses a preparation method of the sensor. The invention utilizes the piezoresistive mechanism generated by the micro deformation and micro contact of the composite fiber to realize the sensing of the normal pressure and the surface tangential force of the flexible sensor, can be applied to the sensing of the frictional force generated when a surface object is contacted, and has great application value for monitoring and sensing the frictional force change and the frictional state between the friction pair.)

1. The utility model provides a flexible force sensor based on compound micro-nanofiber which characterized in that: the sensor comprises a shell, a micron-sized pattern array substrate (1) and conductive ionic gel composite micro-nano fibers (2), wherein the micron-sized pattern array substrate and the conductive ionic gel composite micro-nano fibers are arranged in the shell; photoetching patterns in the form of micro-convex bodies are arranged on the micron pattern array substrate (1); the conductive ionic gel composite micro-nano fiber (2) is attached to the micron-sized pattern array substrate (1), and the conductive ionic gel composite micro-nano fiber (2) is connected with an external lead (3).

2. The flexible force-sensitive sensor based on composite micro-nano fibers according to claim 1, wherein: the micron-sized pattern array substrate (1) is made of a polymer material, and the polymer material refers to one or two of polydimethylsiloxane, polyurethane and polyimide.

3. The flexible force-sensitive sensor based on composite micro-nano fibers according to claim 1, wherein: the photoetching pattern is any one of a square, a cylinder, a rectangular stripe and a pyramid, the distance between every two of the microprotrusions is 5-500 mu m, and the side length or the diameter of each microprotrusion is 1-300 mu m.

4. The flexible force-sensitive sensor based on composite micro-nano fibers according to claim 1, wherein: the conductive ionic gel composite micro-nanofiber (2) is formed by coating conductive ionic gel on the surface of a polymer micro-nanofiber framework material formed by electrostatic spinning.

5. The flexible force-sensitive sensor based on composite micro-nano fibers according to claim 1, wherein: the external lead (3) is a metal lead in enameled wires, aluminum foils and copper foils.

6. The method for preparing the flexible force-sensitive sensor based on the composite micro-nano fiber according to claim 1, comprising the following steps:

preparing a polymer material by using a photoetching method to obtain a micron-sized pattern array substrate (1) with a micro-convex photoetching pattern, cutting the micron-sized pattern array substrate (1) into 40 × 30 × 1 mm rectangular pieces, and attaching the rectangular pieces to a collecting device;

completely dissolving a polymer solute for electrostatic spinning in a solvent to obtain a solution with the mass concentration of 5-50 wt%, transferring the solution into an injector, performing electrostatic spinning on the micron-sized pattern array substrate (1) through an injection pump, and performing vacuum drying treatment to obtain the substrate with the polymer micro-nanofiber framework;

thirdly, dipping and adsorbing the substrate with the polymer micro-nanofiber framework in the ionic gel precursor solution for 2-30 minutes, curing for 5-50 minutes by ultraviolet light, repeating for 3-5 times, and drying to obtain the substrate attached with the conductive ionic gel composite micro-nanofiber (2);

and fourthly, connecting the substrate attached with the conductive ionic gel composite micro-nano fiber (2) with an external lead (3), assembling the substrate in a face-to-face mode, and packaging the substrate into a shell, so that the flexible force-sensitive sensor is obtained.

7. The method for preparing the flexible force-sensitive sensor based on the composite micro-nano fiber according to claim 1, characterized in that: in the second step, the polymer solute for electrostatic spinning is one or more of polylactic acid, polyethylene glycol, polyvinyl alcohol, polylactic acid-glycolic acid copolymer, ethyl cellulose, polyvinylidene fluoride, polystyrene, polycaprolactone and polyvinylpyrrolidone.

8. The method for preparing the flexible force-sensitive sensor based on the composite micro-nano fiber according to claim 1, characterized in that: the solvent of the polymer for electrostatic spinning in the second step is one or more of ethanol, water, acetone, dichloromethane, chloroform, tetrahydrofuran, benzene, toluene, N-dimethylformamide and N, N-dimethylacetamide.

9. The method for preparing the flexible force-sensitive sensor based on the composite micro-nano fiber according to claim 1, characterized in that: the electrostatic spinning method comprises the following steps that the electrostatic spinning conditions include that the environment temperature is 20-27 ℃, the relative humidity is 10-50%, the solution flow rate is 1-4 mL/h, the potential difference is 10-20 kV, the spinning distance is 10-20 cm, and the spinning time is 1-2 h.

10. The method for preparing the flexible force-sensitive sensor based on the composite micro-nano fiber according to claim 1, wherein the ionic gel precursor solution in the step ⑶ is prepared by adding 5-15 g of 1-butyl-3-methylimidazolium tetrafluoroborate into 1-5 mL of HCl with the volume concentration of 37%, uniformly stirring by using a magnetic stirrer, blowing nitrogen for 1min, adding 0.2-1.2 g of tetraethyl silicate, and fully mixingStirring for 2h, and then sequentially adding 0.5-2.5 g N, N-dimethylacrylamide, 3-20 mg of N, N-dimethylacrylamide and 1-5 mg of N, N-dimethylacrylamideαKetoglutaric acid, stirring well and blowing nitrogen for 1 min; sealing and shading with tinfoil paper; drying at 50 deg.C for 48 hr, taking out, unsealing, and shaking to mix well to obtain the final product; or the ionic gel precursor solution is prepared by mixing 3-5 g of butyl acrylate and 5-7 g of 1-butyl-3-methylimidazole bistrifluoromethylsulfonyl imide salt; adding 0.03-0.05 g of 2-hydroxy-2-methyl propiophenone and 1-1.4 g of hexanediol diacrylate, and carrying out ultrasonic treatment for 5 minutes until the materials are uniformly dissolved to obtain the compound.

Technical Field

The invention relates to the technical field of flexible friction sensing and monitoring, in particular to a flexible force-sensitive sensor based on composite micro-nano fibers and a preparation method thereof.

Background

The state monitoring of the kinematic friction pair plays an important role in the stable operation of modern industrial mechanical equipment. Although friction state parameters in the friction process mainly include friction force, friction heat, friction vibration and the like, stable operation of the friction pair is usually directly reflected on stable friction force, and when the friction state of the friction pair changes, the friction force changes accordingly. At present, the monitoring aiming at the running state of the friction pair mainly focuses on oil lubrication, and the oil lubrication state is judged by online measurement of the thickness of an oil film. The monitoring of the friction pair state aiming at dry friction mainly depends on the structural design of integrating the sensor and the system, but devices specially aiming at friction force sensing are lacked.

Electrostatic spinning is a rapid and simple method for manufacturing micro-nanofibers, and the obtained micro-nanofiber material becomes an ideal material of a flexible force-sensitive sensor (Lee S, Sasaki D, Kim D, et al. ultrasoftronics to monitor dynamic fiber sizing carbon elements [ J ] due to the advantages of high specific surface area and high length-diameter ratio, a complex staggered structure between micro-nanofibers and sensitive response to external stress strain].Nature Nanotechnology, 2019, 14(2): 156-160). Ionic gels are not only used in flexible electrodes, but also as active materials for flexible sensing devices (Tee BCK, Wang C, Allen R, BaoZ. An electronic and mechanical self-sealing composites with pressure-and flexibility-sensitive properties for electronic skin applications [ J BCK, Wang C, Allen R, BaoZ].Nature Nanotechnology, 2012, 7: 825.). Therefore, the composite fiber prepared from the fiber and the active material is expected to exert flexibility and sensitive deformation, and the sensitive change of the integral resistance of the active material caused by micro-contact and deformation between the fibers is utilized to sense the external stress strain. In addition, by combining the design of the pattern micro-convex array, the tangential friction force of the sensor surface is converted into lateral fiber connectionTouch, thereby sensitively detecting the surface friction.

Disclosure of Invention

The invention aims to solve the technical problem of providing a flexible force-sensitive sensor based on composite micro-nano fibers, which realizes normal pressure and surface tangential force sensing.

The invention also provides a preparation method of the flexible force-sensitive sensor based on the composite micro-nano fiber.

In order to solve the problems, the invention provides a flexible force-sensitive sensor based on composite micro-nano fibers, which is characterized in that: the sensor comprises a shell, and a micron-sized pattern array substrate and conductive ionic gel composite micro-nanofibers which are arranged in the shell; photoetching patterns in the form of micro-convex bodies are arranged on the micron pattern array substrate; the conductive ionic gel composite micro-nano fiber is attached to the micron-sized pattern array substrate and is connected with an external lead.

The micron-scale pattern array substrate is made of a polymer material, and the polymer material refers to one or two of Polydimethylsiloxane (PDMS), Polyurethane (PU) and Polyimide (PI).

The photoetching pattern is any one of a square, a cylinder, a rectangular stripe and a pyramid, the distance between every two of the microprotrusions is 5-500 mu m, and the side length or the diameter of each microprotrusion is 1-300 mu m.

The conductive ionic gel composite micro-nanofiber is characterized in that conductive ionic gel is coated on the surface of a polymer micro-nanofiber framework material formed by electrostatic spinning.

The external lead is one of a metal lead in an enameled wire, an aluminum foil and a copper foil.

The preparation method of the flexible force-sensitive sensor based on the composite micro-nano fiber comprises the following steps:

preparing a polymer material by using a photoetching method to obtain a micron-sized pattern array substrate with a micro-convex photoetching pattern, cutting the micron-sized pattern array substrate into 40 x 30 x 1 mm rectangular sheets, and attaching the rectangular sheets to a collecting device;

completely dissolving a polymer solute for electrostatic spinning in a solvent to obtain a solution with the mass concentration of 5-50 wt%, transferring the solution into an injector, performing electrostatic spinning on the micron-sized pattern array substrate through an injection pump, and performing vacuum drying treatment to obtain the substrate with the polymer micro-nano fiber skeleton;

thirdly, dipping and adsorbing the substrate with the polymer micro-nanofiber framework in the ionic gel precursor solution for 2-30 minutes, curing for 5-50 minutes by ultraviolet light, repeating for 3-5 times, and drying to obtain the substrate attached with the conductive ionic gel composite micro-nanofiber;

and fourthly, connecting the substrate attached with the conductive ionic gel composite micro-nano fiber with an external lead (3), assembling the substrate in a face-to-face mode, and packaging the substrate into a shell, so that the flexible force-sensitive sensor is obtained.

The collecting device in the step refers to one of a roller, a flat plate, a turntable and a coil mode.

In the second step, the polymer solute for electrostatic spinning is one or more of Polylactic acid (PLA), Polyethylene glycol (PEG), Polyvinyl alcohol (PVA), Polylactic acid-glycolic acid copolymer (PLGA), Ethyl Cellulose (EC), Polyvinylidene fluoride (PVDF), Polystyrene (PS), Polycaprolactone (PCL), Polyvinylpyrrolidone (PVP).

The solvent of the polymer for electrostatic spinning in the second step is one or more of ethanol, water, acetone, Dichloromethane (DCM), chloroform, Tetrahydrofuran (THF), benzene, toluene, N-Dimethylformamide (DMF) and N, N-Dimethylacetamide (DMAC).

The electrostatic spinning method comprises the following steps that the electrostatic spinning conditions include that the environment temperature is 20-27 ℃, the relative humidity is 10-50%, the solution flow rate is 1-4 mL/h, the potential difference is 10-20 kV, the spinning distance is 10-20 cm, and the spinning time is 1-2 h.

The ionic gel precursor solution in the step ⑶ is prepared by mixing 1-butyl-3-methylimidazolium tetrafluoroborate ([ Bmim ]][BF4]) Adding 5-15 g of the mixture into 1-5 mL of HCl with the volume concentration of 37%, uniformly stirring the mixture by using a magnetic stirrer, blowing nitrogen for 1min, and then adding 0.2-1.2 g of tetraethyl silicate (TEOS); fully stirring for 2 hours, and then sequentially adding 0.5-2.5 g N, N-dimethylacrylamide (MBAA), 3-20 mg of N, N-dimethylacrylamide and 1-5 mg of N, N-dimethylacrylamideαKetoglutaric acid (2-OA), stirring uniformly and blowing nitrogen for 1 min; sealing and shading with tinfoil paper; drying at 50 deg.C for 48 hr, taking out, unsealing, and shaking to mix well to obtain the final product; or the ionic gel precursor solution is prepared by mixing 3-5 g of Butyl Acrylate (BA) and 5-7 g of 1-butyl-3-methylimidazolium bistrifluoromethylsulfonyl imide salt ([ Bmim ]][TFSI]) Mixing; adding 0.03-0.05 g of 2-hydroxy-2-methyl propiophenone and 1-1.4 g of hexanediol diacrylate (HDDA), and carrying out ultrasonic treatment for 5 minutes until the mixture is uniformly dissolved to obtain the compound.

When the substrate attached with the conductive ionic gel composite micro-nano fiber is assembled face to face, the skeleton materials of the composite fiber on the substrate are the same or different polymers.

Compared with the prior art, the invention has the following advantages:

the electrostatic spinning micro-nano fiber is used as a flexible framework, the conductive ionic gel is coated to prepare an active sensing material, the flexible sensing material is combined with a flexible substrate with a pattern array design, and a piezoresistive mechanism generated by micro-deformation and micro-contact of composite fibers is utilized to realize sensing of normal pressure and surface tangential force of a flexible sensor, so that the flexible sensing material can be applied to sensing of frictional force generated when a surface object is contacted, and has great application value in monitoring and sensing of frictional force change and frictional state between friction pairs.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

FIG. 1 is a schematic structural diagram of the present invention.

FIG. 2 is a flow chart of the preparation of the present invention.

FIG. 3 is a schematic diagram of a force sensing mechanism of the present invention.

In the figure: 1-micron pattern array substrate; 2-conductive ionic gel composite micro-nano fiber; and 3, externally connecting a lead.

Detailed Description

As shown in fig. 1, a flexible force-sensitive sensor based on composite micro-nanofibers comprises a housing, and a micron-sized pattern array substrate 1 and a conductive ionic gel composite micro-nanofibers 2 disposed in the housing. Photoetching patterns in the form of micro-convex bodies are arranged on the micron-sized pattern array substrate 1; the conductive ionic gel composite micro-nanofiber 2 is attached to the micron-sized pattern array substrate 1, and the conductive ionic gel composite micro-nanofiber 2 is connected with an external lead 3.

Wherein: the micro-scale pattern array substrate 1 is made of a polymer material, which refers to one or two of Polydimethylsiloxane (PDMS), Polyurethane (PU), and Polyimide (PI).

The photoetching pattern is any one of a square, a cylinder, a rectangular stripe and a pyramid, the distance between every two of the microprotrusions is 5-500 mu m, and the side length or the diameter of each microprotrusion is 1-300 mu m.

The conductive ionic gel composite micro-nanofiber 2 is formed by coating conductive ionic gel on the surface of a polymer micro-nanofiber framework material formed by electrostatic spinning.

The external lead 3 is one of a metal lead of an enameled wire, an aluminum foil and a copper foil.

As shown in fig. 2, the preparation method of the flexible force-sensitive sensor based on the composite micro-nanofiber comprises the following steps:

the manufacturing method comprises the steps of preparing a polymer material by using a photoetching method to obtain a micron-sized pattern array substrate 1 with a micro-convex photoetching pattern, cutting the micron-sized pattern array substrate 1 into 40-30-1 mm rectangular pieces, and attaching the rectangular pieces to a collecting device.

Wherein: the collecting device is one of a roller, a flat plate, a rotating disc and a coil mode, and the obtained fibers can be orderly oriented fibers or disorderly and randomly arranged fibers.

Completely dissolving a polymer solute for electrostatic spinning in a solvent to obtain a solution with the mass concentration of 5-50 wt%, transferring the solution into an injector, performing electrostatic spinning on the micron-sized pattern array substrate 1 through an injection pump, and performing vacuum drying treatment to obtain the substrate with the polymer micro-nano fiber skeleton.

Wherein: the polymer solute for electrostatic spinning is one or more of Polylactic acid (PLA), Polyethylene glycol (PEG), Polyvinyl alcohol (PVA), Polylactic acid-glycolic acid copolymer (PLGA), Ethyl Cellulose (EC), Polyvinylidene fluoride (PVDF), Polystyrene (PS), Polycaprolactone (PCL), Polyvinylpyrrolidone (PVP).

The solvent of the polymer for electrostatic spinning is one or more of ethanol, water, acetone, Dichloromethane (DCM), chloroform, Tetrahydrofuran (THF), benzene, toluene, N-Dimethylformamide (DMF), and N, N-Dimethylacetamide (DMAC).

The electrostatic spinning conditions include that the environmental temperature is 20-27 ℃, the relative humidity is 10-50%, the solution flow rate is 1-4 mL/h, the potential difference is 10-20 kV, the spinning distance is 10-20 cm, and the spinning time is 1-2 h.

Thirdly, dipping and adsorbing the substrate with the polymer micro-nano fiber framework in the ionic gel precursor solution for 2-30 minutes, curing for 5-50 minutes by ultraviolet light, repeating for 3-5 times, and drying to obtain the substrate attached with the conductive ionic gel composite micro-nano fiber 2.

Wherein: the ionic gel precursor solution is prepared by mixing 1-butyl-3-methylimidazolium tetrafluoroborate ([ Bmim ]][BF4]) Adding 5-15 g of the mixture into 1-5 mL of HCl with the volume concentration of 37%, uniformly stirring the mixture by using a magnetic stirrer, blowing nitrogen for 1min, and then adding 0.2-1.2 g of tetraethyl silicate (TEOS); fully stirring for 2 hours, and then sequentially adding 0.5-2.5 g N, N-bisMethacrylamide (DMAAM), 3-20 mg N, N-dimethyl bisacrylamide (MBAA) and 1-5 mgαKetoglutaric acid (2-OA), stirring uniformly and blowing nitrogen for 1 min; sealing and shading with tinfoil paper; drying at 50 deg.C for 48 h, taking out, unsealing, and shaking.

Or the ionic gel precursor solution is prepared by mixing 3-5 g of Butyl Acrylate (BA) and 5-7 g of 1-butyl-3-methylimidazole bistrifluoromethylsulfonyl imide salt ([ Bmim ] [ TFSI ]); adding 0.03-0.05 g of 2-hydroxy-2-methyl propiophenone (1173) and 1-1.4 g of hexanediol diacrylate (HDDA), and carrying out ultrasonic treatment for 5 minutes until the mixture is uniformly dissolved to obtain the compound.

And fourthly, connecting the substrate attached with the conductive ionic gel composite micro-nanofiber 2 with an external lead 3, assembling the substrate in a face-to-face mode, and packaging the substrate into a shell, so that the flexible force-sensitive sensor is obtained. In the face-to-face assembly, the matrix material on which the fibers are combined is the same or different polymer.

The working principle of the sensor is shown in fig. 3, when a contact object rubs on the outer surface of the sensor, tangential micro edges and micro displacement occur on the composite fiber sensor layer on the surface of the micro-convex body in the sensor. The micro-nano fibers are stretched or compressed to deform according to a resistance change formula delta R₁Secondly, the fibers attached to the micro-convex surface are deformed by external tangential force to microscopically contact and separate with each other and change the contact area between the fibers, thereby generating contact resistance Δ R₂The change also causes a change in the resistance of the entire sensing active layer. The micro-nano fiber resistance caused by the two microscopic deformations causes the whole resistance change of the whole sensing active fiber layer delta R = delta R₁+ΔR₂Ultimately reflecting the change in friction (tangential force) of the sensor surface.