CN113929826A

CN113929826A - Neuron-like composite conductive hydrogel and multifunctional flexible sensor

Info

Publication number: CN113929826A
Application number: CN202111358696.1A
Authority: CN
Inventors: 张璐; 吴明华; 王诗雯; 余德游; 王莉莉; 王懿佳
Original assignee: Zhejiang Sci Tech University ZSTU
Current assignee: Zhejiang Sci Tech University ZSTU
Priority date: 2021-11-17
Filing date: 2021-11-17
Publication date: 2022-01-14
Anticipated expiration: 2041-11-17
Also published as: CN113929826B

Abstract

The invention discloses a preparation method of neuron-like composite conductive hydrogel, which comprises the following steps: preparing carbon black into modified carbon black; preparing a modified carbon black/one-dimensional conductive material dispersion liquid consisting of modified carbon black, a one-dimensional conductive material and deionized water; the preparation raw materials of the hydrogel neuron-like composite conductive hydrogel comprise the following components: modified carbon black/one-dimensional conductive material dispersion, polyvinyl alcohol, catechol compound, acrylamide, initiator, cross-linking agent and catalyst. The invention also discloses a neuron-like composite conductive hydrogel flexible sensor which is prepared by utilizing the neuron-like composite conductive hydrogel. The flexible sensor of the invention has strain/pressure sensitivity and relatively high sensitivity.

Description

Neuron-like composite conductive hydrogel and multifunctional flexible sensor

Technical Field

The invention belongs to the technical field of multifunctional flexible sensor preparation, and particularly relates to a multifunctional composite conductive hydrogel flexible sensor and a preparation method thereof.

Background

In recent years, flexible wearable sensors have shown great application potential in the fields of human activity monitoring, electronic skin, human-machine interaction, soft robots, and the like. In order to meet the requirements of special people (such as bedridden patients, dyskinesia patients, speech disorder patients and Parkinson disease patients), stretchable, flexible, recoverable, pressure/strain sensitive flexible multifunctional sensors capable of reflecting the health conditions of human bodies in real time are widely researched by people. The conductive hydrogel is used as an important branch of the hydrogel, has the flexibility, resilience, biocompatibility and good mechanical property of the hydrogel, and also has excellent ductility and conductivity, so that the conductive hydrogel draws great attention in a flexible sensor. However, the current conductive hydrogel has the problems of poor mechanical property, single sensitive function and low sensitivity, so that the conductive hydrogel can not meet the requirements of special people. Therefore, the preparation of the conductive hydrogel with pressure/strain responsiveness, high sensitivity and better mechanical properties has important significance.

Disclosure of Invention

The invention aims to solve the technical problem of providing a neuron-like composite conductive hydrogel multifunctional flexible sensor and a preparation method of the neuron-like composite conductive hydrogel used by the same.

In order to solve the technical problems, the invention provides a preparation method of the neuron-like composite conductive hydrogel, which comprises the following steps:

1) preparing the carbon black into modified carbon black;

2) preparing a modified carbon black/one-dimensional conductive material dispersion liquid consisting of modified carbon black, a one-dimensional conductive material and deionized water;

the one-dimensional conductive material: carbon black in a mass ratio of 1: 0.25-4;

in the dispersion liquid of the modified carbon black/one-dimensional conductive material, the sum of the mass concentrations of the modified carbon black and the one-dimensional conductive material is 0.18-0.19 g/21-23 mL;

3) the preparation raw materials of the hydrogel neuron-like composite conductive hydrogel comprise the following components: modified carbon black/one-dimensional conductive material dispersion, polyvinyl alcohol, catechol compound, acrylamide, initiator, cross-linking agent and catalyst;

the polyvinyl alcohol accounts for 17-18 wt% of the total weight of the preparation raw materials;

the pyrocatechol compound accounts for 0.1-1 wt% (preferably 0.5 wt%) of the total weight of the preparation raw materials;

acrylamide accounts for 6-7 wt% (preferably 6.5 wt%) of the total amount of the raw materials;

the mass concentration of the catalyst in the preparation raw material is 0.5-2 per mill (preferably 1 per mill);

initiator: 0.1 wt% to 1 wt% (preferably 0.5 wt%);

a crosslinking agent: 0.01 to 0.1 wt% (preferably 0.05 wt%);

the balance is modified carbon black/one-dimensional conductive material dispersion liquid;

4) adding polyvinyl alcohol into the dispersion liquid of the modified carbon black/one-dimensional conductive material, heating to 90-100 ℃, and reacting for 1.5-2.5 h (preferably reacting for 2h at 90 ℃);

then adding a catechol compound, and reacting at 90-100 ℃ for 0.8-1.2 h (preferably reacting at 90 ℃ for 1 h);

and adding acrylamide, an initiator, a cross-linking agent and a catalyst, and reacting at 50-60 ℃ for 2.5-3.5 h (preferably at 55 ℃ for 3h) to obtain the neuron-like composite conductive hydrogel.

As an improvement of the preparation method of the neuron-like composite conductive hydrogel, in the step 2):

the one-dimensional conductive material is a silver nanowire (preferred), a carbon nanotube, a copper nanowire or a gold nanowire;

(silver nanowires + carbon black): (polyvinyl alcohol + catechol compound + acrylamide) ═ 2.5 to 2.6 wt%.

Description of the drawings: since silver nanowires are generally stored as a dispersion, a 1 wt% AgNWs dispersion may be practically used.

Polyvinyl alcohol + catechol compound + acrylamide ═ hydrogel.

The preparation method of the neuron-like composite conductive hydrogel is further improved as follows:

the catechol compound is catechol, tannic acid, dopamine or alkali lignin;

the initiator is ammonium persulfate, potassium persulfate or azobisisobutyronitrile;

the cross-linking agent is N, N-methylene bisacrylamide, diphenylmethane diisocyanate, acyl chloride or glyoxal;

the catalyst is tetramethylethylenediamine, triethylenediamine or N, N-dimethylcyclohexylamine.

As a further improvement of the preparation method of the neuron-like composite conductive hydrogel, the preparation method of the modified carbon black in the step 1) sequentially comprises the following steps:

adding carbon black and sodium hydroxide into water, stirring until the carbon black is uniformly dispersed and the sodium hydroxide is completely dissolved, and cooling to room temperature to obtain a sodium hydroxide solution dispersed with the carbon black; in the sodium hydroxide solution dispersed with the carbon black, the concentration of the carbon black is 5 g/L-20 g/L (preferably 10g/L), and the concentration of the sodium hydroxide is 400 g/L;

dropping 1.5 +/-0.2 mL of hydrogen peroxide (with the concentration of 30%) into 50mL of the sodium hydroxide solution with the dispersed carbon black obtained in the step I, and reacting at room temperature for 12-20h (preferably 16 h);

and thirdly, centrifuging the reaction liquid obtained in the step II, washing the reaction liquid to be neutral by deionized water, and drying the reaction liquid (drying for 24 hours at the temperature of 80 ℃) to obtain the modified carbon black.

As a further improvement of the preparation method of the neuron-like composite conductive hydrogel, the step III is as follows: the deionized water washing times are 5 times (until the solution is neutral), the drying temperature is 80 ℃, and the drying time is 24 hours.

The invention also provides a neuron-like composite conductive hydrogel flexible sensor: the neuron-like composite conductive hydrogel prepared by the method is used;

arranging a copper foil metal electrode on the surface of the neuron-like composite conductive hydrogel, leading out a lead, and packaging the conductor into a sandwich structure by adopting an insulating flexible packaging material to obtain the neuron-like composite conductive hydrogel flexible sensor.

The improvement of the neuron-like composite conductive hydrogel flexible sensor provided by the invention is as follows: the thickness of the neuron-like composite conductive hydrogel is (0.65 +/-0.05) mm.

The neuron-like composite conductive hydrogel multifunctional flexible sensor is of a sandwich structure, is packaged by adopting an insulating flexible packaging material, and is prepared by arranging a composite conductive hydrogel induction material in the middle.

The invention is used for solving the problems of low sensitivity, lack of pressure responsiveness and the like of the existing hydrogel flexible sensor, has low preparation cost and simple method, and simultaneously has strain/pressure sensitivity and relatively high sensitivity of the flexible sensor.

The invention relates to a neuron-simulated composite conductive hydrogel multifunctional flexible sensor and a preparation method thereof.

In the invention process, the following problems are fully considered:

polyacrylamide (PAM) has a typical three-dimensional network structure, water solubility, non-toxicity, and stability, and is widely spotlighted in the preparation of hydrogels, but its mechanical strength is low, limiting its applications. Polyvinyl alcohol (PVA) is a water-soluble polymer and has the characteristics of good compatibility with various materials, high mechanical strength and the like. Through the combination of PAM and PVA, the mechanical strength of PAM hydrogel can be improved, and the application range of PAM hydrogel is widened. The conductive hydrogel is mainly prepared by embedding conductive materials (such as carbon nanomaterials, metal nanowires/particles and conductive polymers) into a flexible polymer, and the conductive hydrogel is prepared by adding the conductive materials into the hydrogel, and the hydrogel should have strong interaction with the conductive materials, so that the aggregation of nanoparticles can be effectively prevented. The chemical structure of the catechol compound contains a plurality of groups capable of forming hydrogen bonds with other substances, so that the mechanical property of the hydrogel can be obviously improved and the dispersibility of the conductive material can be improved by combining PVA, PAM and the catechol compound.

The human neurons have the functions of sensing stimuli, producing excitement and transmitting excitement. When stimulated, the excitation is transmitted from the cell body of one neuron to the other neuron or nerve cell via the processes and gradually completes the excitation process, which can transmit not only strain changes but also pressure changes. Inspired by human neurons, to prepare neuron-like composite conductive hydrogels, it is expected that conductive materials of similar structure and excellent conductivity can impart human neuron-like properties (e.g., fast response, high sensitivity, and strain/pressure responsiveness) to flexible sensors.

In the present invention, if the "modified carbon black" is changed to "carbon black", the dispersibility of carbon black is not good and the conductive material is not uniform, so that the present invention cannot be realized.

The neuron-like composite conductive hydrogel multifunctional flexible sensor and the preparation method thereof have the beneficial effects that:

1. aiming at the problem of poor mechanical property of the existing hydrogel, the invention combines polyvinyl alcohol, catechol compound and acrylamide to prepare the double-network hydrogel, which has obviously improved mechanical property, better biocompatibility, stretchability and toughness.

2. Aiming at the problems of low sensitivity and lack of pressure responsiveness of the conductive hydrogel, the invention provides a neuron-like structure. The multifunctional flexible sensor of the composite conductive hydrogel is prepared by adopting the modified carbon black and the one-dimensional conductive material to compound and simulate a neuron structure, so that the multifunctional flexible sensor of the composite conductive hydrogel has high sensitivity, pressure/strain responsiveness, conductivity and stability, and has the remoldability.

3. The neuron-like composite conductive hydrogel multifunctional flexible sensor can be applied to the aspects of human motion monitoring, expression recognition, voice recognition and the like, and has wide application prospects in the fields of artificial electronic skin, man-machine interaction, intelligent robots, wearable equipment, health monitoring and the like.

In conclusion, the invention is inspired by human neurons, adopts a one-dimensional conductive material to simulate the structure of human neuron protrusions, adopts carbon black particles to simulate the structure of human neuron cell bodies, and combines hydrogel to prepare the neuron-like composite conductive hydrogel. The composite hydrogel adopts polyacrylamide with a typical three-dimensional network structure, water solubility, nontoxicity and stability as a monomer, adopts polyvinyl alcohol with good compatibility and high mechanical strength to improve the mechanical property of the polyacrylamide, and combines a catechol compound to improve the mechanical property of the hydrogel and improve the dispersibility of a conductive material.

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 neuron-like composite conductive hydrogel multifunctional flexible sensor of the present invention;

FIG. 2 is a neuron picture at the left and a TEM morphology picture of the AgNWs/CB-OH composite material at the right;

FIG. 3 is an SEM topography of the prepared neuron-like composite conductive hydrogel;

FIG. 4 is a graph of the electromechanical properties of the prepared neuron-like composite conductive hydrogel;

the left graph shows the influence of the mass ratio of the modified carbon black to the silver nanowires on the surface resistivity of the composite conductive hydrogel, and the right graph shows the influence of the mass ratio of the modified carbon black to the silver nanowires on the mechanical property of the composite conductive hydrogel;

FIG. 5 shows the sensitivity test results of the prepared neuron-like composite conductive hydrogel;

the left graph is the strain sensitivity test result of the neuron-like composite conductive hydrogel, and the right graph is the pressure sensitivity test result of the neuron-like composite conductive hydrogel;

FIG. 6 shows the stability test results of the prepared neuron-like composite conductive hydrogel;

FIG. 7 shows the result of the test of the remodeling performance of the prepared neuron-like composite conductive hydrogel;

the left graph is a schematic diagram of the remodeling process of the prepared neuron-like composite conductive hydrogel, and the right graph is a stress-strain curve of the composite conductive hydrogel before and after remodeling;

FIG. 8 is a knee bending vibration signal measured by the prepared neuron-like composite conductive hydrogel multifunctional flexible sensor;

FIG. 9 is a vibration signal of the mouth opening action measured by the prepared neuron-like composite conductive hydrogel multifunctional flexible sensor;

FIG. 10 is a vibration signal of the "Thank you" process measured by the prepared neuron-like composite conductive hydrogel multifunctional flexible sensor;

fig. 11 shows the vibration signals of the walking process measured by the prepared neuron-like composite conductive hydrogel multifunctional flexible sensor. Fig. 2, 3, and 5 to 11 are directed to embodiment 4.

Detailed Description

The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto:

in the following cases:

CB, carbon black; CB-OH, modified carbon black (hydroxylated carbon black);

AgNWs, silver nanowires, average diameter of-77.6 nm; the average length is 158.3 mu m;

hydrogen peroxide, 30% (mass fraction) H₂O₂An aqueous solution of (a);

the AgNWs dispersion had an AgNWs concentration of 1g/100 ml.

Embodiment 1, a method for preparing a neuron-like composite conductive hydrogel flexible sensor:

firstly, preparing the neuron-like composite conductive hydrogel, and sequentially carrying out the following steps:

1) preparing the carbon black into modified carbon black:

adding 0.5g of carbon black and 20g of sodium hydroxide into water to fix the volume to 50mL, stirring until the carbon black is uniformly dispersed and the sodium hydroxide is completely dissolved, and cooling to room temperature to obtain a sodium hydroxide solution dispersed with the carbon black; in the sodium hydroxide solution dispersed with the carbon black, the mass fraction of the carbon black is 10g/L, and the concentration of the sodium hydroxide is 400 g/L.

Dropping 1.5mL of hydrogen peroxide with the concentration of 30% into the sodium hydroxide solution with the carbon black dispersed obtained in the step I, and reacting for 16 hours at room temperature; the dropping time was about 5 minutes.

And thirdly, centrifuging the reaction solution obtained in the second step for 5 minutes at the rotating speed of 5000rpm, washing with deionized water (washing with water until the solution is neutral, and washing with deionized water for 5 times), and drying (drying at 80 ℃ for 24 hours) to obtain the modified carbon black CB-OH.

2) Setting the mass ratio of AgNWs to CB-OH as 1:0.25,

adding 14.8mL of silver nanowire dispersion liquid (containing 0.148g of silver nanowires) and 0.037g of modified carbon black into 7.2mL of water (deionized water), and ultrasonically stirring and uniformly dispersing to obtain AgNWs/CB-OH mixed dispersion liquid;

3) and 5.1g of polyvinyl alcohol, 0.15g of catechol compound, 1.92g of acrylamide, 9.6mg of initiator, 0.96mg of cross-linking agent and 0.03g of catalyst to form about 29.4g of raw materials for preparing the hydrogel neuron-like composite conductive hydrogel.

The catechol compound is tannic acid, the initiator is ammonium persulfate, the crosslinking agent is N, N-methylene-bisacrylamide, and the catalyst is tetramethylethylenediamine;

thus:

the polyvinyl alcohol accounts for about 17.3 wt% of the total weight of the preparation raw materials;

the pyrocatechol compound (tannic acid) accounts for about 0.5 wt% of the total weight of the preparation raw materials;

acrylamide accounts for about 6.5 wt% of the total preparation raw materials;

the mass concentration of the catalyst (tetramethylethylenediamine) in the preparation raw material is 1 per mill;

initiator (ammonium persulfate): 0.5 wt% of acrylamide;

crosslinker (N, N-methylenebisacrylamide): acrylamide 0.05 wt%;

4) adding 5.1g of polyvinyl alcohol into the AgNWs/CB-OH mixed dispersion liquid obtained in the step 2), and heating to 90 ℃ for reaction for 2 hours;

then 0.15g of tannic acid is added to react for 1h at 90 ℃;

then, 1.92g of acrylamide, 9.6mg of ammonium persulfate, 0.96mg of N, N-methylene bisacrylamide and 0.03g of tetramethylethylenediamine were added and reacted at 55 ℃ for 3 hours to obtain the neuron-like composite conductive hydrogel (hereinafter referred to as composite conductive hydrogel).

Secondly, preparing the neuron-like composite conductive hydrogel flexible sensor by using the composite conductive hydrogel:

setting the thickness of the composite conductive hydrogel to be (0.65 +/-0.05) mm, cutting the composite conductive hydrogel into 1 multiplied by 4cm, arranging copper foil metal electrodes on the surface of the blocky composite conductive hydrogel, leading out a lead, and packaging the blocky composite conductive hydrogel into a sandwich structure by adopting upper and lower layers of insulating flexible packaging material 3MVHB glue to obtain the neuron-like composite conductive hydrogel flexible sensor. The thickness of the single-sided VHB glue layer is about 1.0 mm.

Examples 2,

Step 2) of example 1 was modified as follows:

setting the mass ratio of AgNWs to CB-OH to be 1:2/3, so in the step 2),

adding 11.1mL of silver nanowire dispersion (containing 0.111g of silver nanowires) and 0.074g of modified carbon black into 10.9mL of water, and uniformly dispersing by ultrasonic stirring to obtain AgNWs/CB-OH mixed dispersion;

the rest is equivalent to embodiment 1.

Examples 3,

Step 2) of example 1 was modified as follows:

setting the mass ratio of AgNWs to CB-OH as 1:1, so in the step 2),

adding 9.25mL of silver nanowire dispersion (containing 0.0925g of silver nanowires) and 0.0925g of modified carbon black into 12.75mL of water, and uniformly dispersing by ultrasonic stirring to obtain CB-OH dispersion;

the rest is equivalent to embodiment 1.

Examples 4,

Step 2) of example 1 was modified as follows:

setting the mass ratio of AgNWs to CB-OH to be 1:3/2, so in the step 2),

adding 7.4mL of silver nanowire dispersion (containing 0.074g of silver nanowires) and 0.111g of modified carbon black into 14.6mL of water, and uniformly dispersing by ultrasonic stirring to obtain a CB-OH dispersion;

the rest is equivalent to embodiment 1.

The SEM topography of the simulated neuron composite conductive hydrogel prepared in example 4 is shown in FIG. 3.

Examples 5,

Step 2) of example 1 was modified as follows:

setting the mass ratio of AgNWs to CB-OH as 1:4, so in the step 2),

adding 3.7mL of silver nanowire dispersion (containing 0.037g of silver nanowires) and 0.148g of modified carbon black into 18.3mL of water, and uniformly dispersing by ultrasonic stirring to obtain a CB-OH dispersion;

the rest is equivalent to embodiment 1.

Experiment 1,

In order to imitate the structure of the neuron and endow the composite conductive hydrogel with more functions, the neuron-imitating composite conductive hydrogel is prepared by combining silver nanowires and modified carbon black with the hydrogel. The morphology structure of the AgNWs/CB-OH composite conductive material is characterized by adopting a transmission electron microscope, as shown in figure 2, the silver nanowires are combined with the modified carbon black to form a structure similar to a neuron. The silver nanowires may function like protrusions, the modified carbon black particles may function like cell bodies, and upon receiving a stimulus, an electrical signal is transmitted from the modified carbon black particles to the silver nanowires and through the silver nanowires to the next one or more modified carbon black particles, which may be beneficial in improving the sensitivity of the composite conductive hydrogel. The results of the remaining examples were not significantly different from those of example 4.

Experiment 2,

Aiming at the embodiment 4, the appearance structure of the neuron-like composite conductive hydrogel is characterized by adopting a scanning electron microscope, as shown in fig. 3, silver nanowires and modified carbon black particles are uniformly distributed in the hydrogel, which shows that a better conductive connection is formed, and the improvement of the performance of the conductive composite hydrogel is facilitated. The results of the remaining examples were not significantly different from those of example 4.

Experiment 3,

The surface resistivity of the composite conductive hydrogel prepared by adding the silver nanowires and the modified carbon black with different mass ratios is tested by adopting a double-electrical measurement four-probe, as shown in Table 1, along with the gradual increase of the content of the modified carbon black in the composite conductive hydrogel, the resistivity of the composite conductive hydrogel shows a trend of firstly decreasing and then increasing, mainly because when the carbon black is less in use amount, the silver nanowires play a conductive role, but the contact resistance existing when the pure silver nanowires are used as a conductive material is larger, the addition of the modified carbon black can effectively reduce the contact resistance of the silver nanowires, when the mass ratio of AgNWs to CB-OH is 1:3/2, the resistivity reaches a minimum value, but the content of the modified carbon black is continuously increased, when the modified carbon black is more in use amount, the modified carbon black mainly plays a conductive role, and the resistance of the modified carbon black is larger than that of the silver nanowires, so when the modified carbon black is more in use amount, the resistivity showed a tendency to rise, and it can be seen that the results of example 4 are best (fig. 4 left).

TABLE 1 surface resistivity (K Ω. cm) of composite conductive hydrogels prepared by AgNWs and CB-OH different mass ratios

Example 1	Example 2	Example 3	Example 4	Example 5
					12.387	11.042	9.015	5.983	15.684

Experiment 4,

The mechanical properties of the composite conductive hydrogel prepared by adding the silver nanowires and the modified carbon black with different mass ratios were tested by a universal experimental material machine, as shown in fig. 4, when the mass of the AgNWs/CB-OH composite conductive material accounts for about 2.58 wt% of the total mass of the hydrogel monomer, the mass ratio of the silver nanowires and the modified carbon black had little influence on the mechanical properties of the composite conductive hydrogel (right in fig. 4).

Experiment 5,

Aiming at embodiment 4, the resistance change rate of the composite conductive hydrogel in the stretching/compressing process is tested by combining a universal experimental material machine and a digital multimeter, so that the sensitivity of the composite conductive hydrogel is obtained. The strain sensitivity coefficient is determined by the formula GF ═ DeltaR/(R)₀ε) calculation, where Δ R is the rate of change of resistance, R is the real-time resistance during stretching, R is the resistance₀The original resistance before stretching, epsilon is the strain change of the composite conductive hydrogel. The pressure sensitivity is determined according to the formula S ═ delta ([ delta ] I/I)₀) Calculation of/δ P, where Δ I is the rate of change of current, I₀The current when no pressure is applied, and P is the applied pressure. As shown in figure 5, when the mass ratio of AgNWs to CB-OH is 1:3/2, the maximum strain sensitivity coefficient of the neuron-like composite conductive hydrogel can reach 68.64, and the pressure sensitivity can reach 0.2290KPa^-1The results show that the prepared neuron-like composite conductive hydrogel has strain/pressure responsiveness and higher sensitivity.

Experiment 6,

For example 4, the composite conductive hydrogel was stretched 50% of its original length by means of a universal test machine combined with a digital multimeter, and the relative resistance change of the composite conductive hydrogel during this procedure was tested by stretching-releasing the composite conductive hydrogel 300 times in cycles. As shown in fig. 6, the maximum value of the relative resistance of the composite conductive hydrogel did not change much during the 300 times of cyclic stretching-releasing, and showed better reproducibility, indicating that the composite conductive hydrogel has better stability. The results of the remaining examples were not significantly different from those of example 4.

Experiment 7,

The plasticity and reusability of the composite conductive hydrogel are very important in the aspect of flexible wearable application, for example, as shown in fig. 7, in order to prove the plasticity of the composite conductive hydrogel, the composite conductive hydrogel is cut into small pieces and added into a beaker, a proper amount of water is added, then the beaker is heated to 90 ℃ for 30min, and the composite conductive hydrogel is found to be gradually dissolved in the water. And then pouring the composite conductive hydrogel solution into a polytetrafluoroethylene template to obtain regenerated composite conductive hydrogel, which shows that the composite conductive hydrogel has plasticity. The mechanical properties of the composite conductive hydrogel before and after regeneration are tested by a universal experimental material machine, and compared with the original gel, the stress-strain curve of the regenerated composite conductive hydrogel is slightly changed but not greatly changed, so that the composite conductive hydrogel is further proved to have good restorability.

Experiment 8,

Aiming at embodiment 4, the composite conductive hydrogel multifunctional flexible sensor is attached to different parts (knee, cheek, throat and sole) of a human body, and is connected with a digital multimeter, so that the relative resistance change of the composite conductive hydrogel multifunctional flexible sensor is tested when the different parts of the human body move, and the composite conductive hydrogel multifunctional flexible sensor is used for real-time detection of human body physiological indexes. Fig. 8 to 11 show that the movements of bending, opening, sounding, walking and the like of the knee of the human body can be detected in real time.

Comparative example 1-1, the amount of polyvinyl alcohol used in example 4 was changed from "17.3 wt%" to "4.1 wt%":

that is, the amount of polyvinyl alcohol used was changed from "5.1 g" to "1.2 g" in example 4. The rest is equivalent to example 4.

Comparative examples 1-2, the amount of polyvinyl alcohol used in example 4 was changed from "17.3 wt%" to "8.2 wt%":

that is, the amount of polyvinyl alcohol used was changed from "5.1 g" to "2.4 g" in example 4. The rest is equivalent to example 4.

Comparative example 2-1, the amount of the catechol compound (i.e., tannic acid) used in example 4 was changed from "0.5 wt%" to "0 wt%":

that is, the amount of tannic acid used was changed from "0.15 g" to "0 g" in example 4. The rest is equivalent to example 4.

Comparative examples 2-2, the amount of the catechol compound (i.e., tannic acid) used in example 4 was changed from "0.5 wt%" to "0.3 wt%":

that is, the amount of tannic acid used was changed from "0.15 g" to "0.09 g" in example 4. The rest is equivalent to example 4.

The results of the above tests of comparative examples 1-1 to 2-2, which were carried out according to the above test, were compared with those of example 4, as shown in Table 2 below:

TABLE 2

The breaking strain of the 4 comparative examples, the composite conductive hydrogel, showed a different decrease.

Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.

Claims

1. The preparation method of the neuron-like composite conductive hydrogel is characterized by comprising the following steps:

1) preparing the carbon black into modified carbon black;

the catechol compound accounts for 0.1 wt% -1 wt% of the total weight of the preparation raw materials;

acrylamide accounts for 6-7 wt% of the total amount of the raw materials;

the mass concentration of the catalyst in the preparation raw materials is 0.5-2 per mill;

initiator: 0.1 to 1 percent by weight of acrylamide;

a crosslinking agent: 0.01 to 0.1 percent by weight of acrylamide;

4) adding polyvinyl alcohol into the dispersion liquid of the modified carbon black/one-dimensional conductive material, heating to 90-100 ℃, and reacting for 1.5-2.5 h;

then adding a catechol compound, and reacting for 0.8-1.2 h at 90-100 ℃;

and adding acrylamide, an initiator, a cross-linking agent and a catalyst, and reacting at 50-60 ℃ for 2.5-3.5 h to obtain the neuron-like composite conductive hydrogel.

2. The method for preparing the neuron-like composite conductive hydrogel according to claim 1, wherein in the step 2):

the one-dimensional conductive material is a silver nanowire, a carbon nanotube, a copper nanowire or a gold nanowire;

3. The preparation method of the neuron-like composite conductive hydrogel according to claim 2, wherein the preparation method comprises the following steps:

the catechol compound is catechol, tannic acid, dopamine or alkali lignin.

4. The preparation method of the neuron-like composite conductive hydrogel according to claim 3, wherein the preparation method comprises the following steps:

5. The preparation method of the neuron-like composite conductive hydrogel according to any one of claims 1 to 4, wherein the preparation method of the modified carbon black of the step 1) comprises the following steps in sequence:

secondly, dripping 1.5 +/-0.2 mL of hydrogen peroxide into 50mL of the sodium hydroxide solution dispersed with the carbon black obtained in the step I, and reacting at room temperature for 12-20 h;

and thirdly, centrifuging the reaction liquid obtained in the step II, washing the reaction liquid to be neutral by deionized water, and drying to obtain the modified carbon black.

6. The preparation method of the neuron-like composite conductive hydrogel according to claim 5, wherein the preparation method comprises the following steps: in the third step: the washing times of the deionized water are 5 times, the drying temperature is 80 ℃, and the drying time is 24 hours.

7. The neuron-like composite conductive hydrogel flexible sensor is characterized in that: the neuron-like composite conductive hydrogel prepared by the method of any one of claims 1 to 6;

8. The neuron-like composite conductive hydrogel flexible sensor of claim 7, wherein: the thickness of the neuron-like composite conductive hydrogel is (0.65 +/-0.05) mm.