Preparation method of CNF / P (AM-co-AA) / Zn < + > conductive hydrogel flexible strain sensor

Abstract

The invention belongs to the technical field of intelligent wearable electronics, and particularly relates to a preparation method of a CNF / P (AM-co-AA) / Zn < + > conductive hydrogel flexible strain sensor. The preparation method comprises the following steps: dissolving carboxylated cellulose nanofibers (CNF) in deionized water, sequentially adding acrylamide (AM), N, N '-methylene bisacrylamide (MBA), ammonium persulfate (APS) and acrylic acid (AA) into a CNF solution, removing bubbles in the solution to obtain a hydrogel prepad fluid, transferring the hydrogel prepad fluid into a mold, and carrying out vacuum drying to obtain the hydrogel. CNF / P (AM-co-AA) hydrogel is obtained through thermal polymerization in a high-temperature environment, ZnCl2 and H2SO4 are dissolved in deionized water to obtain an ionic solution, the prepared hydrogel is soaked in the ionic solution, the hydrogel is taken out after a period of time to obtain conductive hydrogel, copper foils are installed on the two sides of the conductive hydrogel, and finally the flexible strain sensor with excellent mechanical performance is obtained.

Description

Technical Field

[0001] This invention belongs to the field of smart wearable electronics technology, specifically relating to a CNF / P(AM-co-AA) / Zn + A method for fabricating a conductive hydrogel flexible strain sensor, which can be widely used in fields such as human motion and physiological signal detection, medical diagnosis, and human-computer interaction. Background Technology

[0002] In the rapidly developing internet age, wearable flexible electronics have gained widespread attention due to their convenience, speed, and efficient information processing. Currently, conductive hydrogel flexible sensors have wide applications in sports and health, healthcare, personal protection, military camouflage, and aerospace. With the increasing demand for functional wearable textiles, the design and development of conductive hydrogels play a crucial role in advancing smart, technological, and information-driven living. Summary of the Invention

[0003] The purpose of this invention is to prepare a flexible strain sensor with high mechanical strength, small size, wide strain range, and easy wearability. This is achieved through processes such as thermal polymerization and soaking, using a CNF / P(AM-co-AA) / Zn base material. + A conductive hydrogel flexible strain sensor. This flexible strain sensor has a simple fabrication process and exhibits good stability and tensile strength.

[0004] The technical solution adopted in this invention is:

[0005] A CNF / P(AM-co-AA) / Zn + The fabrication method of a conductive hydrogel flexible strain sensor includes the following steps:

[0006] 1) Dissolve carboxylated cellulose nanofibers (CNF) in deionized water and stir until homogeneous to obtain a CNF solution;

[0007] 2) Acrylamide AM, N,N′-methylenebisacrylamide MBA, ammonium persulfate APS and acrylic acid AA were added sequentially to CNF solution and stirred until homogeneous to obtain hydrogel pretreatment solution;

[0008] 3) Remove air bubbles from the hydrogel pretreatment solution under low pressure to obtain a bubble-free hydrogel pretreatment solution;

[0009] 4) Transfer the bubble-free hydrogel pretreatment liquid into the mold and thermally polymerize it at a high temperature to obtain CNF / P(AM-co-AA) hydrogel;

[0010] 5) Immerse the CNF / P(AM-co-AA) hydrogel in an ionic solution containing ZnCl2 and H2SO4, then remove and wash with deionized water to obtain CNF / P(AM-co-AA) / Zn + Conductive hydrogel;

[0011] 6) CNF / P(AM-co-AA) / Zn + Conductive copper foil is attached to both sides of the conductive hydrogel to obtain CNF / P(AM-co-AA) / Zn + Flexible strain sensor.

[0012] Furthermore, in the above preparation method, in step 1), the amount of CNF used is 0.1-0.4g, and the amount of deionized water used is 30.7-31mL.

[0013] Furthermore, in the above preparation method, step 1), the stirring is performed by magnetic stirring at 40°C for 30–60 min.

[0014] Furthermore, in the above preparation method, in step 2), the amount of AM is 4.403g, the amount of MBA is 1.9mg, the amount of APS is 28.26mg, and the amount of AA is 3.426mL.

[0015] Furthermore, in the above preparation method, step 2), the stirring is performed by magnetic stirring at room temperature for 10-15 minutes.

[0016] Furthermore, the above preparation method, step 3), is achieved by the following steps: using a circulating water multi-purpose vacuum pump to extract air from the bottle containing the hydrogel pre-solution to achieve a low-pressure environment, and letting the hydrogel pre-solution stand in the low-pressure environment for 1 hour to remove air bubbles from the hydrogel pre-solution.

[0017] Furthermore, in the above preparation method, step 4), the mold has a size of 30×10×1mm.

[0018] Furthermore, in the above preparation method, step 4), the thermal polymerization is performed by placing the mold in an oven at 65-70°C for 1.5-2 hours.

[0019] Furthermore, in the above preparation method, step 5), the ionic solution containing ZnCl2 and H2SO4 is obtained by adding 6.8143g of ZnCl2 and 0.1mL of concentrated sulfuric acid to 500mL of deionized water.

[0020] Furthermore, in the above preparation method, step 5), the soaking time is 24 hours.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] 1. This invention obtains a CNF / P(AM-co-AA) / Zn based material through processes such as thermal polymerization and soaking. + Conductive hydrogel flexible strain sensor. This method helps the sensor achieve high mechanical strength, and the overall fabrication process is simple and environmentally friendly.

[0023] 2. The preparation method of the present invention is easy to control in terms of performance, that is, the CNF content can be adjusted according to actual needs, thereby controlling different tensile strength and strain range. Attached Figure Description

[0024] Figure 1 The image shows a SEM image of the CNF / P(AM-co-AA) hydrogel prepared in Example 1.

[0025] Figure 2 CNF / P(AM-co-AA) / Zn containing conductive copper foil, as described in Example 1. + Optical image of a conductive hydrogel.

[0026] Figure 3 Example 1: CNF / P(AM-co-AA) / Zn + Strain sensing characteristics of a conductive hydrogel flexible strain sensor.

[0027] Figure 4 CNF / P(AM-co-AA) / Zn with different CNF contents + Strain and stress histograms of conductive hydrogels, ① is a strain histogram, ② is a stress histogram. Detailed Implementation

[0028] Example 1

[0029] (1) CNF / P(AM-co-AA) / Zn + The conductive hydrogel flexible strain sensor is fabricated as follows:

[0030] 1) Add 0.3g of carboxylated cellulose nanofibers (CNF) to 30.9mL of deionized water and stir magnetically at 40℃ for 60min to obtain CNF solution.

[0031] 2) Add 4.403g of acrylamide (AM), 1.9mg of N,N′-methylenebisacrylamide (MBA), 28.26mg of ammonium persulfate (APS) and 3.426mL of acrylic acid (AA) sequentially to CNF solution, and stir magnetically for 10min at room temperature to obtain hydrogel pretreatment solution.

[0032] 3) Use a circulating water multi-purpose vacuum pump to extract air from the bottle containing the hydrogel pretreatment solution to achieve a low-pressure environment. Let the hydrogel pretreatment solution stand in the low-pressure environment for 1 hour to remove air bubbles from the hydrogel pretreatment solution.

[0033] 4) Place the mold (30×10×1mm) containing the bubble-free hydrogel pretreatment solution into an oven at 65-70℃ for thermal polymerization for 1.5-2 hours to obtain CNF / P(AM-co-AA) hydrogel.

[0034] 5) Add 6.8143 g of ZnCl2 and 0.1 mL of concentrated sulfuric acid to 500 mL of deionized water to obtain an ionic solution. Immerse the CNF / P(AM-co-AA) hydrogel in the ionic solution for 24 h. After removing the hydrogel, wash it with deionized water to obtain CNF / P(AM-co-AA) / ZnCl2. + Conductive hydrogel.

[0035] 6) CNF / P(AM-co-AA) / Zn + Conductive copper foil is attached to both sides of the conductive hydrogel to obtain CNF / P(AM-co-AA) / Zn + Flexible strain sensor.

[0036] (ii) Characterization

[0037] Figure 1 The image shows a SEM image of the CNF / P(AM-co-AA) hydrogel prepared in Example 1. Figure 1 This invention indicates that CNF / P(AM-co-AA) hydrogel was successfully prepared.

[0038] Figure 3 The strain sensing characteristics of the CNF / P(AM-co-AA) / Zn+ conductive hydrogel flexible strain sensor in Example 1 are shown in the figure. Figure 3 This demonstrates that the resistance of the conductive hydrogel was tested and recorded in real time with strain using a digital multimeter. Based on CNF / P(AM-co-AA) / Zn + The conductive hydrogel flexible strain sensor has a strain range of 540%. Within the strain range of 0~300%, GF=0.264, and within the strain range of 300~540%, GF=0.61.

[0039] Figure 4 CNF / P(AM-co-AA) / Zn with different CNF contents + Strain and stress bar charts for conductive hydrogels. Figure 4 This indicates that different CNF contents can affect the stress and strain of hydrogels.

Claims

1. A CNF / P(AM-co-AA) / Zn + A method for fabricating a conductive hydrogel flexible strain sensor, characterized in that, Includes the following steps: 1) Dissolve carboxylated cellulose nanofibers (CNF) in deionized water and stir until homogeneous to obtain a CNF solution; 2) Acrylamide AM, N,N′-methylenebisacrylamide MBA, ammonium persulfate APS and acrylic acid AA were added sequentially to CNF solution and stirred until homogeneous to obtain hydrogel pretreatment solution; 3) Remove air bubbles from the hydrogel pretreatment solution under low pressure to obtain a bubble-free hydrogel pretreatment solution; 4) Transfer the bubble-free hydrogel pretreatment liquid into the mold and thermally polymerize it at a high temperature to obtain CNF / P(AM-co-AA) hydrogel; 5) Immerse the CNF / P(AM-co-AA) hydrogel in an ionic solution containing ZnCl2 and H2SO4, then remove and wash with deionized water to obtain CNF / P(AM-co-AA) / Zn + Conductive hydrogel; 6) CNF / P(AM-co-AA) / Zn + Conductive copper foil is attached to both sides of the conductive hydrogel to obtain CNF / P(AM-co-AA) / Zn + Flexible strain sensor.

2. The preparation method according to claim 1, characterized in that, In step 1), the amount of CNF used is 0.1-0.4g, and the amount of deionized water used is 30.7-31mL.

3. The preparation method according to claim 1, characterized in that, In step 1), the stirring is performed by magnetic stirring at 40°C for 30 to 60 minutes.

4. The preparation method according to claim 1, characterized in that, In step 2), the dosage of AM is 4.403g, the dosage of MBA is 1.9mg, the dosage of APS is 28.26mg, and the dosage of AA is 3.426mL.

5. The preparation method according to claim 1, characterized in that, In step 2), the stirring is performed by magnetic stirring at room temperature for 10 to 15 minutes.

6. The preparation method according to claim 1, characterized in that, Step 3) is achieved by the following steps: using a circulating water multi-purpose vacuum pump to extract air from the bottle containing the hydrogel pre-solution to achieve a low-pressure environment, and letting the hydrogel pre-solution stand in the low-pressure environment for 1 hour to remove air bubbles from the hydrogel pre-solution.

7. The preparation method according to claim 1, characterized in that, In step 4), the mold has dimensions of 30×10×1mm.

8. The preparation method according to claim 1, characterized in that, In step 4), the thermal polymerization is performed by placing the mold in an oven at 65-70°C for 1.5-2 hours.

9. The preparation method according to claim 1, characterized in that, In step 5), the ionic solution containing ZnCl2 and H2SO4 is obtained by adding 6.8143g of ZnCl2 and 0.1mL of concentrated sulfuric acid to 500mL of deionized water.

10. The preparation method according to claim 1, characterized in that, In step 5), the soaking time is 24 hours.

Images