Preparation method of non-woven fabric flexible strain sensor based on MXene / TPU composite material

Abstract

The invention discloses a preparation method of a non-woven fabric flexible strain sensor based on an MXene / TPU composite material. The preparation method comprises the following steps: dissolving cetyltrimethylammonium bromide (CTAB) in deionized water, and dipping a cleaned and dried TPU non-woven fabric in a prepared CTAB solution for modification to obtain a CTAB-coated TPU non-woven fabric; the preparation method comprises the following steps: preparing an MXene colloidal solution with a certain concentration, immersing CTAB-coated TPU non-woven fabric into the MXene colloidal solution, and enabling MXene to be uniformly attached to the surface of TPU fiber under the assistance of ultrasonic waves, so as to obtain the flexible strain sensor with excellent performance.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent wearable electronic technology, and specifically relates to a method for preparing a flexible strain sensor based on a MXene / TPU composite non-woven fabric. The flexible strain sensor can be widely used in the fields of human motion and physiological signal detection, medical diagnosis, human-computer interaction, intelligent fabrics, etc. Background Art

[0002] In the Internet era with rapid technological development, wearable flexible electronics have attracted widespread attention due to its convenience and high efficiency in information processing. At present, smart textile-based flexible sensors are widely used in sports health, medical care, personal protection, military camouflage, aerospace and other fields. With the increasing demand for functional wearable textiles, the design and development of smart sensor textiles play an important role in promoting smart life, technological life and information life. Summary of the invention

[0003] The purpose of the present invention is to prepare a flexible strain sensor that is breathable, small in size, light in weight and easy to wear. A flexible strain sensor based on MXene / TPU composite non-woven fabric is obtained through surface modification, impregnation, packaging and other processes. The preparation process of the flexible strain sensor is simple and has good stability and stretchability.

[0004] A method for preparing a flexible strain sensor based on a MXene / TPU composite non-woven fabric comprises the following steps:

[0005] 1) dissolving cetyltrimethylammonium bromide (CTAB) in deionized water and stirring to obtain a CTAB solution;

[0006] 2) washing and drying the TPU non-woven fabric as an elastic substrate, and then immersing it in a CTAB solution and ultrasonically stirring it to obtain a CTAB@TPU non-woven fabric;

[0007] 3) immersing the CTAB@TPU non-woven fabric in a MXene colloidal solution, stirring the solution ultrasonically, and then drying the solution to obtain a MXene / TPU composite non-woven fabric;

[0008] 4) coating the conductive silver paste on the MXene / TPU composite non-woven fabric, so that the conductive silver paste evenly wraps the edge of the non-woven fabric and then solidifies to obtain a MXene / TPU composite non-woven fabric electrode;

[0009] 5) The MXene / TPU composite non-woven fabric electrode is encapsulated with polydimethylsiloxane (PDMS) to obtain a MXene / TPU composite non-woven fabric flexible strain sensor.

[0010] Furthermore, in the above-mentioned preparation method, step 1) is achieved by the following steps: adding 8 to 13 mg of hexadecyltrimethylammonium bromide CTAB powder into 55 to 65 mL of deionized water, and magnetically stirring for 8 to 12 minutes to obtain a 0.2 mg / mL CTAB solution.

[0011] Furthermore, in the above-mentioned preparation method, step 2) is achieved by the following steps: the TPU non-woven fabric is ultrasonically cleaned with deionized water, dried at 50-60° C. as an elastic substrate, and then immersed in a CTAB solution and ultrasonically stirred for 25-35 minutes to obtain a CTAB@TPU non-woven fabric.

[0012] Furthermore, in the above-mentioned preparation method, in step 3), the preparation method of the MXene colloidal solution comprises the following steps:

[0013] 3.1) Preparation of Ti3C2T by chemical etching and ultrasonic exfoliation x MXene solution: First, the etching reaction process is to add LiF to a polytetrafluoroethylene beaker, followed by HCl, and allow the two to fully react for the first time in a magnetic stirring water bath. Then, Ti3AlC2 is added to the polytetrafluoroethylene beaker in small amounts and multiple times. After the lid is sealed, the etching reaction is carried out by stirring in a constant temperature water bath. The solution is poured into a centrifuge tube for centrifugation. Unreacted LiF is first removed with HCl, and then the solution is continuously centrifuged and washed with deionized water until the pH value of the supernatant reaches neutral. The solution in the centrifuge tube is poured into a washing bottle, which is sealed after nitrogen is introduced, and then ultrasonically peeled in an ice bath. After centrifugation again, the upper layer of liquid is Ti3C2T x MXene solution;

[0014] 3.2) Ti3C2T x The MXene solution was diluted to a concentration of 1 mg / mL, stirred, and then ultrasonicated to obtain a MXene colloidal solution.

[0015] Furthermore, in the preparation method of the above-mentioned MXene colloidal solution, in step 3.1), for the first full reaction, the temperature of the water bath is controlled to be 35-45°C, the stirring speed is maintained at 500-700r / min, and the stirring time is 10-20min; during the etching reaction, the stirring speed is still maintained at 500-700r / min, the stirring time is 45-50h, and the reaction temperature is maintained at 35-45°C.

[0016] Furthermore, in the above-mentioned method for preparing the MXene colloidal solution, in step 3.1), Ti3AlC2 is slowly added into a polytetrafluoroethylene beaker in 9 to 10 times, and this process lasts for 20 to 30 minutes.

[0017] Furthermore, in the above-mentioned method for preparing the MXene colloidal solution, in step 3.1), the gas flow rate of the nitrogen gas is maintained at 10 to 12 m / s, and the ventilation time is 0.5 to 1.5 h.

[0018] Furthermore, in the above-mentioned method for preparing the MXene colloidal solution, in step 3.2), the stirring speed is 500 to 700 r / min, and the stirring time is 10 to 20 min.

[0019] Furthermore, in the above-mentioned method for preparing the MXene colloidal solution, in step 3.2), the ultrasonic time is 10 to 20 minutes.

[0020] Furthermore, in the above preparation method, in step 4), the curing temperature is 50-60° C., and the curing time is 0.5-1.5 h.

[0021] Furthermore, in the above-mentioned preparation method, in step 5), the encapsulation treatment is achieved by the following steps: immersing the sensing area of ​​the MXene / TPU composite non-woven fabric electrode in a mixed solution of PDMS prepolymer and curing agent for 25 to 35 seconds and then curing it at 50 to 60° C. for 4 hours.

[0022] Preferably, in the above preparation method, in step 5), the mass ratio of PDMS prepolymer to curing agent is 10:1.

[0023] The MXene / TPU composite non-woven fabric flexible strain sensor provided by the present invention can be used in the fields of human motion and physiological signal detection, human-computer interaction, electronic skin, etc.

[0024] Compared with the prior art, the present invention has the following beneficial technical effects:

[0025] 1. The present invention obtains a flexible strain sensor based on MXene / TPU composite non-woven fabric through surface modification, impregnation, encapsulation and other processes. This method helps the sensor achieve a wide strain range, and the overall preparation process is simple and green.

[0026] 2. The preparation method of the present invention is easy to achieve performance regulation, that is, the concentration of MXene can be adjusted according to actual needs, thereby regulating different sensitivities and strain ranges.

[0027] 3. The fabric-based flexible strain sensor prepared by the present invention has high porosity and excellent stretchability, thereby achieving accurate sensing. At the same time, the thinner highly elastic stretchable fabric as the base provides the possibility of meeting the large deformation of the human body during exercise. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The raw material Ti3AlC2 and the prepared Ti3C2Tx XRD pattern of MXene.

[0029] Figure 2 This is the strain sensing characteristic diagram of the flexible strain sensor based on MXene / TPU composite non-woven fabric prepared in Example 1.

[0030] Figure 3 This is a SEM image of the MXene / TPU composite nonwoven fabric prepared in Example 1, wherein ① the attachment morphology of the nonwoven fabric as a whole, and ② the attachment morphology of a single fiber. DETAILED DESCRIPTION

[0031] Example 1

[0032] (I) The preparation method of the flexible strain sensor based on MXene / TPU composite non-woven fabric is as follows:

[0033] 1) Add 12 mg of cetyltrimethylammonium bromide (CTAB) powder into 60 mL of deionized water and stir magnetically for 10 min to obtain a 0.2 mg / mL CTAB solution.

[0034] 2) The TPU nonwoven fabric was ultrasonically cleaned with deionized water, dried at 60° C. as an elastic substrate, and then immersed in a CTAB solution and ultrasonically stirred for 30 min to obtain a CTAB@TPU nonwoven fabric.

[0035] 3.1) Preparation of Ti3C2T by chemical etching and ultrasonic exfoliation x MXene solution: First, the etching reaction process is to add lithium fluoride (LiF) to a polytetrafluoroethylene beaker, followed by hydrochloric acid (HCl), and allow the two to react fully in a magnetic stirring water bath (the temperature of the water bath is controlled at 40°C, the stirring speed is maintained at 600r / min, and the stirring time is 15min). Then, titanium aluminum carbide (Ti3AlC2) is slowly added to the polytetrafluoroethylene beaker in 10 portions. This process lasts for 20min. After the lid is sealed, the beaker is kept at a constant temperature of 40°C. Stirring in a water bath (stirring speed is still maintained at 600r / min, stirring time is 48h) to carry out etching reaction; pouring the solution into a centrifuge tube for centrifugation, first removing the unreacted LiF with HCl, and then centrifuging and washing the solution with deionized water until the pH value of the supernatant reaches neutral; pouring the solution in the centrifuge tube into a washing bottle, passing nitrogen at a gas flow rate of 12m / s for 1h, sealing it, and ultrasonically peeling it in an ice bath; after centrifugation again, the upper layer of liquid is Ti3C2T x MXene solution;

[0036] 3.2) Ti3C2T xThe MXene solution was diluted to a concentration of 1 mg / mL, stirred at 600 r / min for 15 min, and then ultrasonicated for 10 min to obtain a MXene colloidal solution;

[0037] 3.3) The CTAB@TPU non-woven fabric was immersed in the MXene colloidal solution and ultrasonically stirred for 60 minutes and then dried to obtain a MXene / TPU composite non-woven fabric.

[0038] 4) Apply the conductive silver paste on the MXene / TPU composite non-woven fabric, so that the conductive silver paste evenly wraps the edge of the non-woven fabric and then put it in an oven at 60°C for curing for 1 hour.

[0039] 5) The sensing area of ​​the MXene / TPU composite non-woven fabric electrode was immersed in a mixed solution of polydimethylsiloxane (PDMS) prepolymer and curing agent (the mass ratio of PDMS prepolymer and curing agent was 10:1) for 30 seconds and then cured at 60°C for 4 hours to obtain a MXene / TPU composite non-woven fabric flexible strain sensor.

[0040] (II) Characterization

[0041] Figure 1 The raw material Ti3AlC2 and the prepared Ti3C2T x XRD pattern of MXene. Figure 1 The results show that the present invention successfully prepared MXene nanosheets.

[0042] Figure 1 The raw material Ti3AlC2 and the prepared Ti3C2T x XRD pattern of MXene. The crystal structures of Ti3AlC2 and MXene were analyzed by X-ray diffraction. The diffraction peaks of Ti3AlC2 are located at 9.65°, 19.2°, 34.1°, 38.85°, 41.85°, 60.35°, and 70.4°, corresponding to the (002), (004), (104), (105), (110), and (118) crystal planes, respectively. Comparing the XRD patterns of MXene and Ti3AlC2, it can be seen that the diffraction peak of the (104) crystal plane disappears in the XRD pattern of MXene, indicating that the etching of the Al atomic layer is successful. In addition, the (002) crystal plane of MXene moves forward from 9.65° to 6.4°, indicating that the interlayer spacing increases after etching.

[0043] Figure 2The strain sensing characteristics of the flexible strain sensor based on MXene / TPU composite non-woven fabric prepared in Example 1. A digital multimeter is used to test and record the real-time change of the resistance of the non-woven fabric with strain. The strain range of the flexible strain sensor based on MXene / TPU composite non-woven fabric is 120%. In the strain range of 0-40%, GF=32.4, in the strain range of 40%-80%, GF=225.1, in the strain range of 80%-120%, GF=1593.9.

[0044] Figure 3 The SEM images of the MXene / TPU composite nonwoven fabric prepared in Example 1, ① the attachment morphology of the nonwoven fabric as a whole, ② the attachment morphology of a single fiber. The surface micromorphology of the fiber was characterized using a scanning electron microscope. It can be clearly seen from Figures ① and ② that MXene is evenly attached to the surface of the TPU fiber.

Claims

1. A method for preparing a flexible strain sensor based on MXene / TPU composite non-woven fabric, characterized in that: The steps include: 1) dissolving hexadecyltrimethylammonium bromide (CTAB) in deionized water and stirring to obtain a CTAB solution; 2) washing and drying the TPU non-woven fabric as an elastic substrate, and then immersing it in a CTAB solution and ultrasonically stirring it to obtain a CTAB@TPU non-woven fabric; 3) immersing the CTAB@TPU non-woven fabric in a MXene colloidal solution, stirring the solution ultrasonically, and then drying the solution to obtain a MXene / TPU composite non-woven fabric; 4) coating the conductive silver paste on the MXene / TPU composite non-woven fabric, so that the conductive silver paste evenly wraps the edge of the non-woven fabric and then solidifies to obtain a MXene / TPU composite non-woven fabric electrode; 5) The MXene / TPU composite non-woven fabric electrode is encapsulated with polydimethylsiloxane to obtain a MXene / TPU composite non-woven fabric flexible strain sensor.

2. The preparation method according to claim 1, characterized in that: Step 1) is achieved by the following steps: 8-13 mg of hexadecyltrimethylammonium bromide (CTAB) powder is added to 55-65 mL of deionized water, and magnetically stirred for 8-12 minutes to obtain a 0.2 mg / mL CTAB solution.

3. The preparation method according to claim 1, characterized in that: Step 2) is achieved by the following steps: the TPU non-woven fabric is ultrasonically cleaned with deionized water, dried at 50-60° C. as an elastic substrate, and then immersed in a CTAB solution and ultrasonically stirred for 25-35 minutes to obtain a CTAB@TPU non-woven fabric.

4. The preparation method according to claim 1, characterized in that: In step 3), the method for preparing the MXene colloidal solution comprises the following steps: 3.1) Preparation of Ti3C2T by chemical etching and ultrasonic exfoliation x MXene solution: First, the etching reaction process is to add LiF to a polytetrafluoroethylene beaker, followed by HCl, and allow the two to fully react for the first time in a magnetic stirring water bath. Then, Ti3AlC2 is added to the polytetrafluoroethylene beaker in small amounts and multiple times. After the lid is sealed, the etching reaction is carried out by stirring in a constant temperature water bath. The solution is poured into a centrifuge tube for centrifugation. Unreacted LiF is first removed with HCl, and then the solution is continuously centrifuged and washed with deionized water until the pH value of the supernatant reaches neutral. The solution in the centrifuge tube is poured into a washing bottle, which is sealed after nitrogen is introduced, and then ultrasonically peeled in an ice bath. After centrifugation again, the upper layer of liquid is Ti3C2T x MXene solution; 3.2) Ti3C2T x The MXene solution was diluted to a concentration of 1 mg / mL, stirred, and then ultrasonicated to obtain a MXene colloidal solution.

5. The preparation method according to claim 4, characterized in that: In step 3.1), for the first full reaction, the temperature of the water bath is controlled at 35-45°C, the stirring speed is maintained at 500-700 r / min, and the stirring time is 10-20 min; during the etching reaction, the stirring speed is still maintained at 500-700 r / min, the stirring time is 45-50 h, and the reaction temperature is maintained at 35-45°C.

6. The preparation method according to claim 4, characterized in that: In step 3.1), Ti3AlC2 is slowly added into the polytetrafluoroethylene beaker in 9 to 10 times, and this process lasts for 20 to 30 minutes.

7. The preparation method according to claim 4, characterized in that: In step 3.1), the gas flow rate of the nitrogen is maintained at 10-12 m / s, and the ventilation time is 0.5-1.5 h.

8. The preparation method according to claim 4, characterized in that: In step 3.2), the stirring speed is 500-700 r / min, the stirring time is 10-20 min, and the ultrasonic time is 10-20 min.

9. The preparation method according to claim 1, characterized in that: In step 4), the curing temperature is 50-60° C. and the curing time is 0.5-1.5 h.

10. The preparation method according to claim 1, characterized in that: In step 5), the encapsulation treatment is achieved by the following steps: immersing the sensing area of ​​the MXene / TPU composite non-woven fabric electrode in a mixed solution of PDMS prepolymer and curing agent for 25 to 35 seconds and then curing it at 50 to 60° C. for 4 hours, wherein the mass ratio of PDMS prepolymer to curing agent is 10:1.

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