CN113461997A

CN113461997A - Strain sensing material, size measuring glove, and preparation method and application thereof

Info

Publication number: CN113461997A
Application number: CN202110437921.4A
Authority: CN
Inventors: 邓华; 傅强; 赵国杰; 武永康
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2021-04-22
Filing date: 2021-04-22
Publication date: 2021-10-01

Abstract

The invention discloses a strain sensing material, a size measuring glove, a preparation method and application thereof. The preparation method of the strain sensing material comprises the following steps: the mixture of the carbon nano tube, the amino silane coupling agent and the solvent is arranged on the surface of the elastic matrix material and then dried to obtain the elastic matrix material; the solvent is toluene and/or n-hexane. The strain sensing material disclosed by the invention has stronger sensitivity in a larger deformation range on the premise of not using a metal conductive material, and can realize accurate measurement.

Description

Strain sensing material, size measuring glove, and preparation method and application thereof

Technical Field

The invention relates to a strain sensing material, a size measuring glove, a preparation method and application thereof.

Background

In some specific application environments, the size of the object cannot be measured by a specific measuring tool, for example, in the medical operation, when a doctor determines the size of a wound or a tumor, the doctor needs to use a measuring scale, and in some medical operations, the doctor cannot use the measuring tool, and the doctor can only rely on visual measurement to measure the size of the target size, so that the more accurate measurement cannot be performed.

Some strain sensing materials have been disclosed in the prior art for measuring physical quantities such as dimensions, but the measurement range is limited and the sensitivity is poor. For example, chinese patent document CN208171170U discloses a flexible tensile strain type resistance sensor, in which a sensing element is a strain sensing material made by filling a conductive substance in a rubber matrix material, and a certain sensitivity and a certain measurement range can be achieved only by using a large amount of conductive substance. Chinese patent document CN109407836A discloses a flexible strain sensor, which includes a conductive fabric, and an upper fixing layer and a lower fixing layer covering the upper and lower surfaces of the conductive fabric, and further fixes the conductive fabric in a non-elastic fixing and accommodating space formed therebetween, so as to limit the relationship between the stretching amount and the resistance change characteristic of the conductive fabric within a linear measurable range. From this patent, it is known that one of the reasons for fixing the conductive fabric is that the conductive fabric can only achieve accurate measurement within a certain deformation range, the deformation range is greatly limited, the measurement range is small, and the presence of the non-elastic material fixing layer may interfere with the accuracy of the measurement. In addition, the conductive fabric in the patent is prepared by plating conductive metal on the fabric, or adopting metal fibers, or blending conductive materials and the fabric, and the conductivity is not good so that the sensitivity in the final test is not high.

Chinese patent document CN106895931A discloses a flexible stress sensor with high sensitivity and large deformation. The nanowire structure is arranged between the flexible material and the conducting layer, so that the deformation range and the measurement sensitivity are enhanced. But due to the presence of the nanowire structure, it is usually only possible to coat the nanowire with metal to form a film, and metals with higher conductive properties are required. High cost, poor corrosion resistance and poor chemical stability.

In summary, the prior art lacks a strain sensing material, which can still accurately measure in a large deformation range without using a metal material with high cost and easy corrosion, and has better sensitivity.

Disclosure of Invention

The invention aims to overcome the defects that the size is usually measured by adopting the current estimation mode in the scene that a measuring tool is inconvenient to use in the prior art, accurate measurement can be realized only in a small range even if a strain sensing material is adopted for measurement, the sensitivity is poor, and in the prior art, in order to obtain the strain sensing material with high sensitivity and large deformation amount, a metal conductive material with high cost and high possibility of corrosion is usually used, and provides a strain sensing material, a size measuring glove, a preparation method and application thereof. The strain sensing material disclosed by the invention has stronger sensitivity in a larger deformation range on the premise of not using a metal conductive material, and can realize accurate measurement.

At present, in the prior art, a mixture of a carbon nanotube, a silane coupling agent and a solvent is prepared by using a strong polar solvent such as acetone, DMF or DMSO and the like, and the mixture cannot be uniformly covered on the surface of an elastic matrix material. For example, when DMF is used as a solvent, when "a mixture of carbon nanotubes, a silane coupling agent and a solvent" is disposed on the surface of the elastic base material, the carbon nanotubes cannot form a uniform conductive coating on the surface of the elastic base material; when acetone is used as a solvent, the carbon nanotubes cannot penetrate into the surface layer of the elastic base material, and the deformation range and the sensitivity of the obtained strain sensing material are obviously poorer than those of the application.

For example, in example 1 of chinese patent document CN110218416A, a strain-resistance response sensitive smart sensor material is prepared by dispersing carbon nanotubes and a silane coupling agent KH560 in acetone, and adding a surfactant, a curing agent, and the like. The initial resistance of the smart material is in the megaohm range, while the initial resistance of the strain sensing material in the invention is between dozens and hundreds of ohms, the measurement range of the strain sensing material in the patent is obviously lower than that in the application due to the larger initial resistance, and meanwhile, the high resistance also means large energy consumption.

The invention solves the technical problems through the following technical scheme.

The invention provides a preparation method of a strain sensing material, which comprises the following steps: the mixture of the carbon nano tube, the amino silane coupling agent and the solvent is arranged on the surface of the elastic matrix material and then dried to obtain the elastic matrix material; the solvent is toluene and/or n-hexane.

Through multiple experiments, the applicant finds that the conditions of adopting n-hexane and/or toluene, matching with an aminosilane coupling agent and the like can realize good dispersion of the carbon nano-tubes, difficult agglomeration and uniform coating on the surface of the elastic base material; and the surface layer of the elastic base material can be swelled, and the carbon nano tubes can further penetrate into the surface layer of the elastic base material through the swelling action. Therefore, the strain sensing material disclosed by the invention is low in energy consumption, and has a larger deformation range and higher sensitivity.

In the present invention, the mass ratio of the carbon nanotubes to the aminosilane coupling agent may be conventional in the art, and is preferably 1: (1 to 4), for example, 1: 3. as known to those skilled in the art from the preparation method of the strain sensing material, the mass ratio refers to the mass ratio in the mixture of the carbon nanotubes, the aminosilane coupling agent and the solvent.

In the present invention, in the "mixture of carbon nanotubes, aminosilane coupling agent and solvent", the mass-to-volume ratio of the carbon nanotubes to the solvent is preferably 0.5 to 2mg/mL, for example, 1 mg/mL.

In the invention, the content of the carbon nano tube arranged on the surface of the elastic base material can be reasonably selected according to actual needs. Preferably, the surface of the elastic base material contains 1-2 mg of the carbon nano-tube per square centimeter.

In the present invention, the carbon nanotube is preferably a multi-walled carbon nanotube.

In the present invention, the diameter of the carbon nanotube is preferably 9 to 10nm, for example, 9.5 nm.

In the present invention, the length of the carbon nanotube is preferably 1.2 to 1.7 μm, for example, 1.5 μm.

In the specific embodiment of the invention, the carbon nanotube is an NC-7000 thin-wall multi-wall carbon nanotube produced by Nanocyl SA, Belgium.

In the present invention, the kind of the aminosilane coupling agent is preferably KH550 and/or KH 792.

In the present invention, the elastic base material may include one or more of polyurethane resin, PBAT, PDMS, natural rubber, and synthetic rubber, such as PDMS. The PDMS generally refers to polydimethylsiloxane conventionally used in the art for preparing strain sensing materials.

In the invention, the shape of the elastic base material can be in a fabric shape, a film shape or a gel shape.

Wherein the textile-like elastomeric matrix material may be prepared by preparation methods conventional in the art, such as wet spinning or electrospinning.

When the shape of the elastic base material is a film or gel, the elastic base material can be in a porous structure.

In the present invention, the preparation method of the "mixture of carbon nanotubes, aminosilane coupling agent and solvent" may be conventional in the art. Preferably comprising the steps of: the carbon nano tube, the silane coupling agent and the solvent are mixed.

Wherein, the mixing order is preferably that the amino silane coupling agent is dissolved in the solvent, and then the carbon nano-tube is added.

Wherein the mixing is preferably ultrasonic and/or stirring. Such as the sequential operations of sonication and agitation.

When the mixing manner includes ultrasound, the time of ultrasound may be 20 to 40min, for example, 30 min.

When the mixing manner includes stirring, the stirring time may be 2 to 4 hours, for example, 3 hours.

In the present invention, the manner of disposing on the surface of the elastic base material preferably includes coating, spraying, blade coating, suction filtration or dipping.

When spray coating is used, it is known to those skilled in the art that a spray gun or a spray can is used to apply the "mixture of carbon nanotubes, aminosilane coupling agent and solvent" to the surface of the elastomeric base material.

In the present invention, the operation of providing the surface of the elastic base material is usually performed at room temperature. The temperature of the room temperature is generally 20 to 30 ℃, for example, 25 ℃.

In the present invention, the "mixture of carbon nanotubes, aminosilane coupling agent and solvent" is preferably further subjected to plasma treatment before being applied to the surface of the elastic base material.

The power of the plasma treatment is preferably 900-1100W, such as 1000W.

The temperature of the plasma treatment is preferably 20 to 30 ℃, for example, 25 ℃.

The atmosphere of the plasma treatment may be, for example, air.

In the invention, the plasma treatment is combined with the mixture of the carbon nanotubes, the aminosilane coupling agent and the solvent, so that the sensitivity of the strain sensing material can be further remarkably improved.

In the present invention, the drying means may be a means for removing the solvent, which is conventional in the art. Such as by drying or airing.

The invention also provides a strain sensing material which is prepared by adopting the preparation method.

The invention also provides a pair of size measuring gloves, which comprise glove bodies, an external output device and the strain sensing material;

and two ends of the external output device are connected with two ends of the strain sensing material end to end through leads.

In the invention, the external output device can be a multimeter, for example. The universal meter can directly display current data, and the operation is simpler.

The invention also provides an application of the strain sensing material as a dimension measuring tool.

On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.

The reagents and starting materials used in the present invention are commercially available.

The positive progress effects of the invention are as follows: the strain sensing material disclosed by the invention has stronger sensitivity in a larger deformation range on the premise of not using a metal conductive material, and can realize accurate measurement.

Drawings

FIG. 1 shows the position of the strain sensing material fixed to the finger joint in example 1.

FIG. 2 is a schematic diagram of the dimensional measurement glove of example 1 showing the linear relationship between deformation and resistance measured by a universal tester and a Piano meter.

Fig. 3 is a schematic diagram of a cycle test method of the linear relationship between the deformation amount and the resistance of the strain sensing material in example 1.

Fig. 4 is a schematic view of example 1 in which stretching was performed using a stretching apparatus while measuring the resistance by a resistance measuring apparatus.

FIG. 5 is a graph showing the change of resistance signal during the measurement process of the size measuring glove in example 1.

FIG. 6 is a graph of resistance versus time for the strain sensing material of example 1 at a strain of 1%.

FIG. 6a is a graph showing the time-dependent change of the resistance when the strain amount of the strain sensing material of example 1 is in the range of 0.25 to 1%. FIG. 6b is an enlarged view of 0-60 s shown in FIG. 6 a.

FIG. 7 is a graph of resistance versus time for the strain sensing material of example 1 at a 5% strain.

FIG. 7a is a graph showing the time-dependent change of the resistance when the strain amount of the strain sensing material of example 1 is in the range of 0.5 to 5%. FIG. 7b is an enlarged view of 0-50 s in FIG. 7 a.

FIG. 8 is a graph showing the change of resistance with time when the strain sensor material of example 1 has a strain amount of 30%.

FIG. 8a is a graph showing the time-dependent change in the resistance of the strain sensing material of example 1 when the strain amount is in the range of 5 to 30%. FIG. 8b is an enlarged view of 0-100 s in FIG. 8 a.

FIG. 9 is a graph showing the change of resistance with time when the strain sensor material of example 1 has a strain amount of 80%.

FIG. 9a is a graph showing the time-dependent change of the resistance of the strain sensing material of example 1 when the strain amount is in the range of 20 to 80%. FIG. 9b is an enlarged view of 0-50 s in FIG. 9 a.

FIG. 10 is a graph of the linear relationship of resistance to deformation for various size measuring gloves of examples 1 and 2 and comparative examples 1 and 2, as measured.

FIG. 11 is a linear plot of resistance versus amount of deformation for the sizing glove of example 3, as measured.

FIG. 12 is a linear plot of resistance versus amount of deformation for the sizing glove of example 4, as measured.

FIG. 13 is a linear plot of resistance versus amount of deformation for the sizing glove of example 5, as measured.

FIG. 14 is an SEM scanning electron micrograph of the strain sensing material of example 1 taken from the unstretched state to a gradually increasing tensile strength. FIG. 14a is an SEM image of unstretched film, and FIGS. 14b, 14c and 14d are SEM images of gradually increasing tensile strength, respectively.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.

The carbon nanotubes of inventive examples 1-5, comparative example 1 and comparative example 2 were obtained from NC-7000 thin-walled multi-walled carbon nanotubes manufactured by Nanocyl SA, Belgium, and had a diameter of 9.5nm and a length of 1.5 μm.

Example 1

The preparation method of the strain sensing material comprises the following steps: dissolving conductive filler carbon nano tubes in n-hexane, adding an aminosilane coupling agent KH550, performing ultrasonic dispersion for 30 minutes, and stirring for 3 hours to fully mix the carbon nano tubes and the aminosilane coupling agent KH550 in the n-hexane to obtain a mixture to be sprayed. Wherein the mass ratio of the carbon nanotubes to the aminosilane coupling agent KH550 is 1: and 3, the mass-volume ratio of the carbon nano tube to the n-hexane is 1 mg/mL.

And transferring the mixture to be sprayed into a spray can or a spray gun, uniformly spraying the mixture on the surface of a PDMS film at room temperature, wherein each square centimeter of the surface of the PDMS film contains 1-2 mg of carbon nanotubes, and airing or drying the mixture at room temperature to obtain the strain sensing material.

Size measuring gloves: comprises a glove body, a multimeter and the strain sensing material prepared by the method. The strain sensing material is cut into strips, and two ends of the strip are respectively fixed at the joints of the glove, as shown in fig. 1, wherein A, B, C, D, E, F, G, H, I, J, K and L are respectively the positions where the strain sensing material is fixed at the joints of the glove.

Example 2

The aminosilane coupling agent was KH792, and the rest of the preparation process and the settings of the parameters were the same as those of example 1.

Example 3

The carbon nanotubes and the aminosilane coupling agent KH550 were mixed well in toluene, and the rest of the preparation process and the setting of the parameters were the same as those of example 1.

Example 4

The carbon nanotubes were thoroughly mixed with the aminosilane coupling agent KH792 in toluene, and the rest of the preparation process and the settings of the parameters were the same as in example 1.

Example 5

In this embodiment, after the PDMS film is subjected to plasma treatment at room temperature of 25 ℃, the mixture to be sprayed is uniformly sprayed on the surface of the PDMS film at room temperature, the power of the plasma treatment is 1000W, the temperature of the plasma treatment is 25 ℃, and the rest of the preparation processes and parameters are set as in embodiment 1.

Comparative example 1

The aminosilane coupling agent was not used and the rest of the preparation process and the settings of the parameters were the same as in example 1.

Comparative example 2

The silane coupling agent used was KH610, and the rest of the preparation processes and parameter settings were the same as in example 1.

Effect example 1

FIG. 2 is a graph showing the linear relationship between the deformation and resistance of the glove for measuring dimensions in example 1, using a universal tester and a Pian meter. FIG. 3 is a schematic view showing a cycle test method of linear relationship between deformation amount and resistance of the glove for size measurement in example 1. Fig. 4 is a schematic view of example 1 in which stretching was performed using a stretching apparatus while measuring the resistance by a resistance measuring apparatus. The method for testing the linear relationship between the deformation amount and the resistance in examples 2 to 5 and comparative examples 1 and 2 is the same as that in example 1.

(1) The test results of examples 1 to 5 and comparative examples 1 and 2 are specifically as follows:

figure 5 shows that the resistance of the sizing glove of example 1 remains relatively constant during the stretching cycle.

As shown in fig. 6, the strain sensing material of example 1 had a dimension of 31 × 10 × 0.41mm, and the amount of strain varied from 0.25% to 1%, as a function of resistance and time. FIG. 6a is a graph showing the time-dependent change of the resistance when the strain amount of the strain sensing material of example 1 is in the range of 0.25 to 1%. FIG. 6b is an enlarged view of 0-60 s shown in FIG. 6 a.

As shown in fig. 7, the strain sensing material of example 1 had dimensions of 31 × 10 × 0.41mm, the amount of strain stretched from 0.5% to 5%, and the resistance as a function of time. FIG. 7a is a graph showing the time-dependent change of the resistance when the strain amount of the strain sensing material of example 1 is in the range of 0.5 to 5%. FIG. 7b is an enlarged view of 0-50 s in FIG. 7 a. Through experimental detection, the strain sensing material in the embodiment 1 is changed from stretching to returning to the original shape, and when the cycle is more than 500 times, accurate measurement can still be realized, the maximum resistance after stretching is 790-830 omega, and the resistance after recovery is stabilized at 327-335 omega. The strain sensing materials of examples 2-5 can still achieve accurate measurements when cycled for more than 500 cycles.

As shown in fig. 8, the strain sensing material of example 1 had a dimension of 34 × 10 × 0.41mm, and the amount of deformation was varied from 5% to 30%, and the resistance was plotted against time. FIG. 8a is a graph showing the time-dependent change in the resistance of the strain sensing material of example 1 when the strain amount is in the range of 5 to 30%. FIG. 8b is an enlarged view of 0-100 s in FIG. 8 a.

As shown in fig. 9, the strain sensing material of example 1 had a dimension of 35 × 10 × 0.41mm, and the amount of strain varied from 20% to 80%, and the resistance was plotted against time. FIG. 9a is a graph showing the time-dependent change of the resistance of the strain sensing material of example 1 when the strain amount is in the range of 20 to 80%. FIG. 9b is an enlarged view of 0-50 s in FIG. 9 a.

According to the linear change graphs obtained from the graphs in FIGS. 6-9, when the deformation amount is 1%, the resistance is 792-827 Ω, and it can be obtained that the strain sensing material of the present invention generates an obvious signal even if a small deformation occurs, and thus, accurate measurement can be achieved. When the deformation amount is 5%, the resistance is 2500-2560 omega. When the deformation amount is 30%, the resistance is 40100-41200 omega. When the deformation amount is 80%, the resistance is 279000-299000 omega.

FIG. 14 is an electron micrograph of the strain sensing material of example 1 taken up to gradually increase the tensile strength when unstretched. FIG. 14a is an SEM image of the unstretched state, and FIGS. 14b, 14c and 14d are SEM images of the gradually increasing tensile strength, respectively. As can be seen from the figure, under the action of the tensile force, cracks are generated on the carbon nanotube layer on the surface of the strain sensing material, so that the resistance changes, and further the measurement is realized. Meanwhile, the thickness of the strain sensing material is measured to be 100-1000 mu m.

(2) The sensitivity factor calculation formula is as follows:

where R is the resistance after stretching, R0 is the initial resistance before stretching, and ε is the amount of deformation. From this calculation formula, it can be seen that the higher the resistance finally measured, the higher the sensitivity factor.

As can be seen from fig. 10, in the example 2 of the present invention, not only the measured deformation range can reach 300%, but also the final measured resistance is 2 × 10⁴The sensitivity factor is also significantly higher than the comparative examples. While the sensitivity factor is obviously lower when no aminosilane coupling agent is added in the comparative example 1, the silane coupling agent used in the comparative example 2 is KH610, and is phenyltrimethoxysilane, the relationship between the resistance and the deformation amount is not linear, and accurate measurement cannot be realized.

As can be seen from fig. 11 and 12, the deformation amounts of the embodiments 3 and 4 of the present invention can be up to 540% and 440%, respectively, and the sensitivity factor is also high.

As can be seen from fig. 13, in the example 5 of the present invention, since the plasma processing is used, only data of the deformation amount up to 20% can be temporarily measured due to the limitation of the resistance in the measuring apparatus (i.e., the resistance sharply increases after the deformation of more than 20% and exceeds the measuring range of the measuring apparatus), but a larger deformation amount can still be realized after the deformation amount reaches 20%, and the measured resistance can reach 4.3 × 10 at 20% of the deformation amount⁷。

Claims

1. A preparation method of a strain sensing material is characterized by comprising the following steps: the mixture of the carbon nano tube, the amino silane coupling agent and the solvent is arranged on the surface of the elastic matrix material and then dried to obtain the elastic matrix material; the solvent is toluene and/or n-hexane.

2. The method for preparing the strain sensing material according to claim 1, wherein in the mixture of the carbon nanotubes, the aminosilane coupling agent and the solvent, the mass ratio of the carbon nanotubes to the aminosilane coupling agent is 1: (1 to 4), for example, 1: 3;

and/or in the mixture of the carbon nanotubes, the aminosilane coupling agent and the solvent, the mass-to-volume ratio of the carbon nanotubes to the solvent is 0.5-2 mg/mL, such as 1 mg/mL.

3. The method of preparing a strain sensing material according to claim 1, wherein 1 to 2mg of the carbon nanotubes are contained per square centimeter of the surface of the elastic base material;

and/or the carbon nanotube is a multi-wall carbon nanotube, such as NC-7000 thin-wall multi-wall carbon nanotube produced by Nanocyl SA, Belgium;

and/or the diameter of the carbon nano tube is 9-10 nm, such as 9.5 nm;

and/or the length of the carbon nano tube is 1.2-1.7 μm, such as 1.5 μm;

and/or, the type of the aminosilane coupling agent is KH550 and/or KH 792.

4. The method of preparing a strain sensing material according to any of claims 1 to 3, wherein the elastic matrix material comprises one or more of polyurethane resin, PBAT, PDMS, natural rubber and synthetic rubber, such as PDMS;

and/or the elastic base material is in a film shape or a gel shape.

5. The method of preparing a strain sensing material according to claim 4, wherein the method of preparing the mixture of carbon nanotubes, aminosilane coupling agent and solvent comprises the steps of: mixing the carbon nano tube, the amino silane coupling agent and the solvent;

wherein, the mixing sequence is preferably that the amino silane coupling agent is dissolved in the solvent, and then the carbon nano-tube is added;

wherein the mixing is preferably ultrasonic and/or stirring;

the time of the ultrasonic treatment is preferably 20-40 min, such as 30 min;

the stirring time is preferably 2 to 4 hours, for example 3 hours.

6. The method for preparing the strain sensing material according to any one of claims 1 to 5, wherein the method for preparing the strain sensing material on the surface of the elastic base material comprises coating, spraying, blade coating, suction filtering or dipping;

when the spraying mode is adopted, a spraying gun or a spraying kettle is preferably adopted to arrange the mixture of the carbon nano tubes, the amino silane coupling agent and the solvent on the surface of the elastic base material;

and/or, the operation of arranging on the surface of the elastic base material is carried out at room temperature, and the room temperature is preferably 20-30 ℃, such as 25 ℃.

7. The method for preparing the strain sensing material according to any one of claims 1 to 6, wherein the method for preparing the strain sensing material further comprises plasma treatment;

wherein, the power of the plasma treatment is preferably 900-1100W, such as 1000W;

wherein the temperature of the plasma treatment is preferably 20 to 30 ℃, for example, 25 ℃.

8. A strain sensing material, which is prepared by the method for preparing the strain sensing material according to any one of claims 1 to 7.

9. A sizing glove comprising a glove body, an external output device, and the strain sensing material of claim 8;

and the two ends of the external output device are connected with the two ends of the strain sensing material end to end through leads.

10. Use of the strain sensing material of claim 8 as a dimensional measurement tool.