CN113817104A

CN113817104A - Quasi-dual-network hydrogel and preparation method and application thereof

Info

Publication number: CN113817104A
Application number: CN202111192888.XA
Authority: CN
Inventors: 徐海华; 曾国正; 张利华
Original assignee: Shenzhen University
Current assignee: Shenzhen University
Priority date: 2021-10-13
Filing date: 2021-10-13
Publication date: 2021-12-21

Abstract

The invention provides a quasi-double-network hydrogel and a preparation method and application thereof. The quasi-double-network hydrogel prepared by the invention comprises the raw materials of sodium alginate, acrylamide, glycol, chloride and the like. According to the invention, ethylene glycol is introduced into a traditional hydrogel system, and hydroxyl in the ethylene glycol is combined with water molecules of the hydrogel to form hydrogen bonds, so that the hydrogel is endowed with excellent moisture retention, and measurement misalignment caused by water loss in the use process of a device is avoided. The finally prepared quasi-double-network hydrogel has good biocompatibility, no toxicity, no harm, water absorption and retention and electrical conductivity. The stress and electric signal acquisition device prepared based on the hydrogel has high sensitivity and stable electric signal under low tensile strain, can be applied to wearable equipment, and monitors human motion signals by being attached to the body surface. The contact impedance of the electrode with the skin of the human body is lower than that of a commercial electrode in the human body physiological electric signal acquisition frequency band, and the measurement of the physiological electric signals such as myoelectricity, electrocardio-electricity, electroencephalogram and the like can be carried out on the body surface of the human body.

Description

Quasi-dual-network hydrogel and preparation method and application thereof

Technical Field

The invention relates to the field of functional polymer composite materials, in particular to a quasi-dual-network hydrogel and a preparation method and application thereof.

Background

The hydrogel is a high molecular soft and wet material which is formed by crosslinking a high molecular material containing hydrophilic groups through intermolecular covalent bonds and bond sites such as hydrogen bonds, has a three-dimensional network structure and contains a large amount of water (50-90%). Compared with the traditional metal sensor, the hydrogel has good adhesiveness, can realize stretching, bending and even twisting, can be applied to more complex curved surface shapes, and is suitable for more and more complex application environments. Conductive hydrogels, in combination with electrical conductivity and flexibility, have attracted considerable attention in the field of wearable devices over the last decade.

The conductive hydrogel can be prepared directly by introducing conductive fillers such as metal particles, carbon nano powder, silver nanowires and the like into the hydrogel, but the hydrogel prepared by the method generally has the problem that conductive components are aggregated into clusters and cannot be uniformly distributed, so that the conductivity of the hydrogel is poor. The stress sensor or the electric signal acquisition device prepared based on the conductive hydrogel also has the problems of single function, poor tensile property, low sensitivity, unstable conductivity and the like, and has certain defects when being used as a wearable stress and electric signal acquisition device.

Therefore, the prior art has yet to be improved.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide a quasi-double-network hydrogel and a preparation method and application thereof, and aims to solve the problems of poor tensile property, low sensitivity and unstable conductivity of a stress sensor or an electric signal acquisition device prepared based on conductive hydrogel in the prior art.

The technical scheme of the invention is as follows:

in a first aspect, the present invention provides a method for preparing a quasi-double-network hydrogel, wherein the method comprises the steps of:

dissolving sodium alginate, acrylamide, glycol and chloride in water, and uniformly mixing to obtain a first mixed solution;

adding an initiator and a cross-linking agent into the first mixed solution, and uniformly mixing to obtain a second mixed solution;

adding an initiator aid into the second mixed solution, and uniformly mixing to obtain a pre-polymerization solution;

and injecting the pre-polymerization solution into a mold, and reacting under the conditions of heating, illumination or radiation to obtain the quasi-dual-network hydrogel.

The preparation method of the quasi-double-network hydrogel comprises the step of preparing the quasi-double-network hydrogel, wherein the mass ratio of the sodium alginate to the acrylamide is 1 (4-10).

The preparation method of the quasi-double-network hydrogel comprises the step of mixing ethylene glycol and water according to a mass ratio of (0.27-1.08): 7.

The preparation method of the quasi-double-network hydrogel comprises the step of preparing a quasi-double-network hydrogel, wherein the chloride salt comprises at least one of potassium chloride, sodium chloride or lithium chloride.

The preparation method of the quasi-double-network hydrogel comprises the step of mixing the chloride salt and water according to a mass ratio of (0.1-1) to 28.

The preparation method of the quasi-double-network hydrogel comprises the following steps of preparing an initiator, a cross-linking agent and an auxiliary initiator, wherein the initiator is ammonium persulfate, the cross-linking agent is N, N ' -methylene bisacrylamide, and the auxiliary initiator is N, N, N ', N ' -tetramethyl ethylenediamine.

The preparation method of the quasi-double-network hydrogel comprises the following steps of enabling the mass ratio of ammonium persulfate to acrylamide to be 1:100, enabling the mass ratio of N, N ' -methylene bisacrylamide to acrylamide to be 0.0006:1, and enabling the using amount of N, N, N ', N ' -tetramethyl ethylenediamine to be 6.25 mu L/1g of acrylamide.

In a second aspect, the present invention provides a quasi-double-network hydrogel, wherein the quasi-double-network hydrogel is prepared by any one of the preparation methods described above.

A quasi-dual network hydrogel device, wherein the device comprises a quasi-dual network hydrogel as described above and a lead connected to the quasi-dual network hydrogel.

In a third aspect, the invention provides an application of the quasi-double network hydrogel device in a stress and electric signal acquisition device.

Has the advantages that: the quasi-double-network hydrogel provided by the invention is prepared from the raw materials of sodium alginate, acrylamide, glycol, chloride salt and the like. The sodium alginate is a pure natural substance, the prepared hydrogel has good biocompatibility and is non-toxic and harmless, and the damage to the skin caused by the stress and electric signal acquisition device prepared based on the hydrogel when the stress and electric signal acquisition device is in contact with the skin of a human body is greatly reduced. In addition, the glycol is added into the traditional hydrogel system, and the idea that the hydroxyl in the glycol is combined with the water molecules in the hydrogel to form hydrogen bonds is utilized, so that the hydrogel is endowed with excellent moisture retention, and the phenomenon of inaccurate measurement caused by water loss in the use process of a device is avoided. Moreover, compared with the traditional alginate/acrylamide hydrogel preparation system, the hydrogel system disclosed by the invention omits the process of adding divalent calcium ions to promote alginate to form a network, so that the formed quasi-double network is of a sodium alginate/polyacrylamide structure. The quasi-double network structure of the invention determines that the hydrogel prepared by the invention has higher sensitivity compared with the traditional alginate/acrylamide hydrogel. The stress and electric signal acquisition device prepared based on the hydrogel is stable in electric signal and high in sensitivity, can be used for monitoring limb movements (such as finger, wrist, throat movements and the like) of a human body in real time, and can be used for acquiring human body physiological electric signals because the contact impedance of the stress and electric signal acquisition device with the skin of the human body under a human body physiological signal acquisition frequency band is lower than the human body skin contact impedance of a commercial silver/silver chloride electrode, thereby providing great application value for the fields of biosensors, wearable equipment, physiological signal acquisition and the like and having great market prospect.

Drawings

FIG. 1 is a preferred flow chart of a method for preparing a quasi-double-network hydrogel according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a hydrogel device according to an embodiment of the present invention.

FIG. 3 is a graph showing the relative resistance change at 0% to 40% strain for different two-network hydrogel devices prepared in examples 1 and 5 of the present invention.

FIG. 4 shows the initial resistance values of quasi-dual network hydrogel devices prepared in examples 1-4 of the present invention.

FIG. 5 is a graph of the relative resistance change at 0% to 40% strain for quasi-dual network hydrogel devices prepared in examples 2-4 of the present invention.

Figure 6 is a graph showing the skin contact impedance changes of quasi-two-network hydrogel devices prepared in examples 1-2 of the present invention.

Wherein, 1-conductive adhesive film; 2-quasi-double-network hydrogel film.

Detailed Description

The invention provides a quasi-dual-network hydrogel and a preparation method and application thereof, and the invention is further described in detail below in order to make the purpose, technical scheme and effect of the invention clearer and more clear. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In a first aspect, an embodiment of the present invention provides a method for preparing a quasi-double-network hydrogel, as shown in fig. 1, including the steps of:

s10, dissolving sodium alginate, acrylamide, glycol and chloride in water, and uniformly mixing to obtain a first mixed solution;

s20, adding an initiator and a cross-linking agent into the first mixed solution, and uniformly mixing to obtain a second mixed solution;

s30, adding an initiator aid into the second mixed solution, and uniformly mixing to obtain a pre-polymerization solution;

s40, injecting the pre-polymerization solution into a mold, and reacting under the conditions of heating, illumination or radiation to obtain the quasi-double-network hydrogel.

The double-network hydrogel is a composite hydrogel formed by interpenetrating two polymers, crosslinking entanglement and the like, wherein two groups of components exist in a crosslinking network form, and the two networks are mutually penetrated. In the quasi-double-network hydrogel system, only one component exists in the form of a cross-linked network, and the other component is entangled on the cross-linked network in the form of linear molecular chains. In the quasi-double-network hydrogel system prepared by the invention, a polyacrylamide network formed by polymerization exists in a cross-linked network form; entangled on the cross-linked network in the form of linear molecular chains is a sodium alginate network. The key difference between the preparation methods of the quasi-double-network hydrogel and the double-network hydrogel is whether part of divalent and trivalent metal ions are introduced into the system. If divalent and trivalent metal ions which can generate cross-linking effect with sodium alginate are introduced, the double-network hydrogel is prepared; if not introduced, the hydrogel is a quasi-double-network hydrogel. In the traditional sodium alginate/acrylamide double-network hydrogel system, the sodium alginate can be crosslinked with most of divalent and trivalent metal ions, such as Ca²⁺，Cu²⁺，Fe³⁺And the like. Compared with the traditional double-network hydrogel, the quasi-double-network hydrogel prepared by the invention has weaker ion binding capacity, so that the ion mobility in the quasi-double network has larger change degree under the same stretching state, and macroscopically shows that the resistance change is more obvious.

In some embodiments, the method for preparing the quasi-double network hydrogel comprises the following specific steps:

s100, dissolving acrylamide and sodium alginate in deionized water, and uniformly mixing to obtain a mixed solution I;

s200, dissolving ethylene glycol into the mixed solution I obtained in the step S100 to obtain a mixed solution II;

s300, dissolving chloride into the mixed solution II obtained in the step S200 to obtain a mixed solution III;

s400, dissolving an initiator and a cross-linking agent into the mixed solution III obtained in the step S300, and removing bubbles after complete dissolution to obtain a mixed solution IV;

s500, adding an auxiliary initiator into the mixed solution IV obtained in the step S400 under an ice bath condition, and uniformly mixing to obtain a mixed pre-polymerization solution;

and S600, injecting the mixed pre-polymerization solution obtained in the step S500 into a mold attached with a conductive adhesive film, and reacting for 1h under the conditions of water bath heating and ultraviolet irradiation to obtain the quasi-double-network hydrogel.

The quasi-double-network hydrogel prepared by the embodiment of the invention can be used for preparing hydrogels with different forms, such as hydrogel films, according to different molds, but is not limited to the hydrogel films. In the embodiment of the present invention, the hydrogel device sample prepared in step S600 is shown in fig. 2, and specifically includes a conductive adhesive film 1 and a quasi-double-network hydrogel film 2, where the conductive adhesive film 1 is embedded in the quasi-double-network hydrogel film 2.

In some embodiments, the mass ratio of sodium alginate to acrylamide is 1 (4-10).

The hydrogel prepared based on sodium alginate has good biocompatibility and can be in direct contact with skin. However, the single hydrogel prepared based on sodium alginate has the problems of poor mechanical property and poor water absorption and retention property, and is difficult to meet the requirements of the wearable sensor for stress and electric signal acquisition devices, such as good adhesiveness and good stretchability, and can be monitored for a long time. The quasi-double-network hydrogel prepared by the sodium alginate and the acrylamide can make up the defect of single hydrogel, enhance the mechanical property of the hydrogel, enable the hydrogel to be tightly attached to the body surface of a human body, and is favorable for improving the stability and the anti-interference performance of the hydrogel during long-term work. The mass ratio of the sodium alginate to the acrylamide is 1 (4-10), and if the mass ratio is more than 1:4, the hydrogel sample prepared is difficult to form; if the mass ratio is less than 1:10, the mechanical properties of the prepared hydrogel sample are poor. In some preferred embodiments, the mass ratio of sodium alginate to acrylamide is 1: 8. When the mass ratio of the sodium alginate to the acrylamide is 1:8, the obtained hydrogel has excellent mechanical properties and is easy to form.

In some embodiments, the mass ratio of ethylene glycol to water is (0.27-1.08): 7.

According to the invention, the glycol is introduced into the quasi-dual-network hydrogel system, and the idea that the hydroxyl in the glycol is combined with the water molecules in the hydrogel to form hydrogen bonds is utilized, so that the water absorption and water retention of the hydrogel are further improved, the hydrogel is endowed with excellent moisture retention, can be stored in the air for a long time, the phenomenon of measurement misalignment caused by water loss in the using process of a device is avoided, and the requirement of long-term monitoring is met. The mechanical property of the hydrogel is influenced by the proportion of the glycol to the water, and the hydrogel prepared by the method has better mechanical property when the mass ratio of the glycol to the water is determined to be (0.27-1.08): 7. In some preferred embodiments, the ethylene glycol to water mass ratio is 0.54: 7.

In some embodiments, the chloride salt comprises at least one of potassium chloride, sodium chloride, or lithium chloride. The initial resistance value of the quasi-double-network hydrogel can be obviously reduced by additionally introducing chloride salt, so that the hydrogel has excellent conductivity.

In some embodiments, the mass ratio of chloride salt to water is (0.1-1): 28. With the increase of the amount of the chloride salt, the initial resistance value of the quasi-double network hydrogel shows a tendency to decrease. However, during the preparation process, the sodium alginate is separated out due to the fact that the chloride salt concentration is too high. Therefore, the mass ratio of the chloride salt to the water is controlled to be (0.1-1):28, so that the initial resistance value of the quasi-double network hydrogel can be reduced, the quasi-double network hydrogel has better conductivity, and the sodium alginate molecules can be ensured to be completely dissolved in an aqueous phase system.

In some preferred embodiments, the mass ratio of chloride salt to water is 0.5: 28.

In some preferred embodiments, the chloride salt is sodium chloride.

In some embodiments, the initiator is ammonium persulfate. The function of the ammonium persulfate is to initiate free radical polymerization reaction of acrylamide, so that a covalent cross-linked macromolecular structure is formed.

In some preferred embodiments, the mass ratio of ammonium persulfate to acrylamide is 1: 100.

In some embodiments, the crosslinking agent is N, N' -methylenebisacrylamide, which functions to form a covalently crosslinked network with acrylamide monomers.

In some preferred embodiments, the mass ratio of N, N' -methylenebisacrylamide to acrylamide is 0.0006: 1.

In some embodiments, the co-initiator is N, N' -tetramethylethylenediamine, which functions to catalyze the production of free radicals by ammonium persulfate to initiate the polymerization of acrylamide monomers.

In some preferred embodiments, the N, N, N ', N' -tetramethylethylenediamine is used in an amount of 6.25. mu.L/1 g acrylamide.

In some embodiments, the heating, lighting, or irradiation condition is water bath heating, ultraviolet irradiation.

In some embodiments, the water bath heating temperature is from 50 ℃ to 65 ℃.

Preferably, the water bath heating temperature is 50 ℃.

In some embodiments, the water bath heating time is 0.5h to 2 h.

Preferably, the water bath heating time is 1 h.

In some embodiments, the ultraviolet radiation has an ultraviolet lamp wavelength of 254nm and a power of 8W.

In a second aspect, an embodiment of the present invention further provides a quasi-double-network hydrogel, where the quasi-double-network hydrogel is prepared by any one of the preparation methods described above.

In this embodiment, the raw materials for preparing the quasi-double-network hydrogel include: sodium alginate, acrylamide, ethylene glycol, N, N ' -methylene bisacrylamide, ammonium persulfate and N, N, N ', N ' -tetramethyl ethylenediamine.

The hydrogel based on sodium alginate has good biocompatibility and can be in direct contact with the skin. However, the single hydrogel prepared based on sodium alginate has the problems of poor mechanical property and poor water absorption and retention property, and is difficult to meet the requirements of the wearable sensor for stress and electric signal acquisition devices, such as good adhesiveness and good stretchability, and can be monitored for a long time. In the embodiment, the quasi-double-network hydrogel is prepared from sodium alginate and acrylamide, so that the defect of a single hydrogel can be overcome, the mechanical property of the hydrogel is enhanced, the hydrogel can be tightly attached to the body surface of a human body, and the stability and the anti-interference performance of the hydrogel during long-term working are improved. Meanwhile, the ethylene glycol is introduced into a quasi-dual-network hydrogel system, so that the water absorption and retention of the hydrogel are further improved, the hydrogel can be stored in the air for a long time, and the requirement of long-term monitoring is met.

In some embodiments, the quasi-double network hydrogel has a thickness of 1.9mm to 2.1mm, a length of 2.9mm to 3.1mm, and a width of 1.4mm to 1.6mm, wherein the two electrically conductive adhesive films are separated from the proximal hydrogel edge by a distance of 0.9mm to 1.1 mm. The thickness of the hydrogel affects the elastic modulus of the hydrogel. The length and width of the hydrogel can be regarded as the contact surface area with the human body. Since the principle of measurement is capacitive coupling, the area of the contact surface at this time affects the capacitance. When the contact surface is infinitely large, the capacitance is infinitely small. Therefore, the thickness and the contact area of the hydrogel used in the test are fixed to be one value as much as possible, and experimental errors caused by unnecessary factors are reduced as much as possible. However, this is not meant to limit the invention, and embodiments of the invention may be made with other suitable thicknesses and length and width dimensions as may be desired.

The embodiment of the invention also provides a quasi-dual-network hydrogel device, which comprises the quasi-dual-network hydrogel and a lead connected with the quasi-dual-network hydrogel.

In some embodiments, the leads may be embedded in the quasi-double network hydrogel, or may be electrically connected to the quasi-double network hydrogel in any other desired manner.

In a third aspect, an embodiment of the present invention further provides an application of the quasi-dual-network hydrogel device described above in a stress and electrical signal acquisition device.

The stress and electric signal acquisition device prepared from the hydrogel disclosed by the embodiment of the invention has stable electric signal and high sensitivity, can be used for monitoring limb movements (such as finger, wrist, throat movements and the like) of a human body in real time, and can be used for acquiring human body physiological electric signals because the contact impedance of the stress and electric signal acquisition device with the skin of the human body under a human body physiological signal acquisition frequency band is lower than the human body skin contact impedance of a commercial silver/silver chloride electrode.

In some embodiments, the quasi-dual network hydrogel devices are applied to biosensors, wearable devices, and physiological signal acquisition devices.

The hydrogel device prepared by the invention has good biocompatibility, high sensitivity and good conductivity, can be used as a wearable stress and electric signal acquisition device to be applied to the fields of rehabilitation, medical monitoring and the like, and has great application potential.

The following is a further explanation of the quasi-double-network hydrogel of the present invention, its preparation method and application by specific examples:

example 1

The preparation method of the quasi-double-network hydrogel comprises the following steps:

(1) adding 0.5g of sodium alginate and 4g of acrylamide into 28mL of deionized water, and stirring until the sodium alginate and the acrylamide are completely dissolved to obtain a mixed solution I;

(2) adding 2mL of ethylene glycol into the mixed solution I to obtain a mixed solution II;

(3) adding 0g of sodium chloride into the mixed solution II, and stirring until the sodium chloride is completely dissolved to obtain a mixed solution III;

(4) adding 40mg of ammonium persulfate and 2.4mg of N, N '-methylene-bisacrylamide into the mixed solution (c), and stirring until the ammonium persulfate and the N, N' -methylene-bisacrylamide are completely dissolved to obtain a mixed solution (c);

(5) under ice bath conditions, 1mL of an aqueous suspension containing 0.01935g N, N' -tetramethylethylenediamine was added to the mixed solution r. Uniformly mixing to obtain a mixed pre-polymerization solution;

(6) and (3) injecting the mixed pre-polymerization solution into a mold attached with a conductive adhesive film, and reacting for 1h under the conditions of water bath heating at 50 ℃ and ultraviolet irradiation to obtain a quasi-dual-network hydrogel device sample.

Example 2

The preparation process of example 2 differs from that of example 1 in that the amount of sodium chloride used in step (3) is 0.5 g.

Example 3

The preparation process of example 3 differs from that of example 1 in that the amount of sodium chloride used in step (3) is 0.8 g.

Example 4

The preparation method of example 4 is different from that of example 1 in that the amount of sodium chloride used in step (3) is 1 g.

Example 5

The preparation method of the double-network hydrogel comprises the following steps:

(4) adding 40mg of ammonium persulfate and 2.4mg of N, N '-methylene bisacrylamide into the mixed solution (c), and stirring until the ammonium persulfate and the N, N' -methylene bisacrylamide are completely dissolved to obtain a mixed solution (c);

(5) and injecting the mixed solution IV into a mold attached with the conductive adhesive film. 1mL of an aqueous suspension containing 0.01935g of N, N, N ', N' -tetramethylethylenediamine and 0.00265g of calcium sulfate was added to the mold.

(6) And (3) reacting for 1h under the conditions of water bath heating at 50 ℃ and ultraviolet irradiation to obtain a sample of the traditional double-network hydrogel device.

Test results

1. Quasi-double-network structure hydrogel and sensitivity test of double-network structure hydrogel

The hydrogel samples prepared in example 1 and example 5 were subjected to a sensory test, wherein the hydrogel prepared in example 1 was a quasi-double-network hydrogel, the aqueous suspension in example 5 contained calcium sulfate, and the hydrogel prepared in example 5 was a double-network hydrogel. The specific test process is as follows: the hydrogel sample is placed on a precise electric translation table (PSA400-11-X, Beijing Zhuo Li Han optical instrument) with a certain size, conductive copper sheets are used as electrode materials at two ends to be communicated with a digital source meter (K2612B, Keithley), the tensile elongation and the step length are automatically controlled by a two-phase stepping motor controller (SC300, Beijing Zhuo Li Han optical instrument), and meanwhile, a computer terminal MATLAB program connected with the digital source meter is used for obtaining the resistance under different strains, wherein the voltage provided by the digital source meter is 1V. The test results are shown in fig. 3.

As can be seen from FIG. 3, the relative rates of change of the electrical resistance of the hydrogels of both structures gradually increased with the change of the stretching. The sensitivity of the traditional double-network hydrogel under 0-40% tensile strain is 2.75, and the sensitivity of the quasi-double-network hydrogel under the same tensile strain can reach 3.95. Therefore, under the same tensile strain, the relative resistance change rate of the quasi-double-network hydrogel is obviously greater than that of the traditional double-network hydrogel.

2. Effect of different amounts of chloride on initial resistance of the hydrogel prepared

The resistance values of the quasi-double-network hydrogel samples prepared in examples 1 to 4 were measured under the following conditions: the hydrogel samples were placed on a platform of a certain size, both ends of which were connected to a digital source meter (K2612B, Keithley) using a conductive copper sheet as an electrode material, wherein the initial resistance value was taken as the resistance value at a voltage of 1V.

The test results are shown in fig. 4, and specific values are shown in table 1.

TABLE 1 Effect of sodium chloride dosage on initial hydrogel resistance values

Numbering	Sodium chloride dosage (g)	Initial resistance value (omega)
			Example 1	0	14183.4
Example 2	0.5	7801.7
			Example 3	0.8	4349.19
Example 4	1	2641.4

As can be seen from fig. 4 and table 1, the initial resistance value of the quasi-double network hydrogel showed a tendency to decrease with the increase of the amount of sodium chloride. The initial resistance value of the double-network hydrogel can be obviously reduced by additionally introducing sodium chloride ions, so that the hydrogel has excellent conductivity. When the amount is 1g, the initial resistance value of the quasi-twin-network hydrogel is about 2641.4 Ω, which is about five times lower than that when sodium chloride is not used. Meanwhile, in the preparation process, the sodium alginate is separated out due to the fact that the concentration of the sodium chloride is too high. When the content of sodium chloride in the mixed pre-polymerization liquid system is more than 1g, sodium alginate molecules can not be completely dissolved in the water phase system.

3. Application of quasi-dual-network hydrogel in strain sensor

In order to study the application of the quasi-double network hydrogel in the strain sensor, the quasi-double network hydrogel samples prepared in examples 2 to 4 were subjected to sensing performance tests. The specific test process is as follows: the hydrogel sample is placed on a precise electric translation table (PSA400-11-X, Beijing Zhuo Li Han optical instrument) with a certain size, conductive copper sheets are used as electrode materials at two ends to be communicated with a digital source meter (K2612B, Keithley), the tensile elongation and the step length are automatically controlled by a two-phase stepping motor controller (SC300, Beijing Zhuo Li Han optical instrument), and meanwhile, a computer terminal MATLAB program connected with the digital source meter is used for obtaining the resistance under different strains, wherein the voltage provided by the digital source meter is 1V. The test results are shown in fig. 5.

As can be seen from FIG. 5, under the strain of 0% -20%, the relative resistance change rate strain changes of the quasi-dual network hydrogel with different sodium chloride dosage are almost consistent; under the strain of 20% -40%, the relative resistance change rate of the quasi-double network hydrogel with different sodium chloride dosage shows different changes, which is specifically shown in the following that the higher the sodium chloride dosage is, the lower the relative resistance change rate is, the higher the relative resistance change rate is, wherein when the sodium chloride dosage is 0.5g, under the strain of 40%, the relative resistance change rate is about 90%.

4. Application of quasi-dual-network hydrogel in acquisition of physiological electric signals

To investigate the use of quasi-two-network hydrogels in the acquisition of physiological electrical signals, skin contact impedance tests were performed on the hydrogel samples prepared in examples 1 and 2. The specific test process comprises placing hydrogel sample with the same size at the designated position of human body surface skin, and connecting two ends with LCR (E4980AL-032, Keysight Technologies) by using anisotropic conductive film (CONNECTORS P/N HST-9805-210, ELform) to test. Meanwhile, a commercial electrode sheet (X-1, Hangzhou Dudao radio, Inc.) was used as a skin contact impedance control group for the test. The test results are shown in fig. 6.

As can be seen from FIG. 6, the skin contact impedance of the quasi-double network hydrogel without sodium chloride is significantly higher than that of the commercial electrode sheet in the whole test range (1-1000 Hz). The skin contact impedance of the quasi-double network hydrogel added with 0.5g of sodium chloride is obviously lower than that of a commercial electrode plate in the whole test range, and the use of the sodium chloride is proved to be capable of effectively reducing the skin contact impedance of the quasi-double network hydrogel device.

In conclusion, the invention provides a quasi-double-network hydrogel and a preparation method and application thereof. The quasi-double-network hydrogel prepared by the invention has good biocompatibility, no toxicity or harm, water absorption and retention property and electrical conductivity. The stress and electric signal acquisition device prepared based on the hydrogel has high sensitivity and stable electric signal under low tensile strain, and can be applied to wearable equipment for monitoring human motion signals by being attached to the body surface. Meanwhile, the contact impedance of the electrode and the skin of the human body is lower than that of a commercial electrode in the human body physiological electric signal acquisition frequency band, and the measurement of the physiological electric signals such as myoelectricity, electrocardio, electroencephalogram and the like can be carried out on the body surface of the human body.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims

1. A preparation method of quasi-double-network hydrogel is characterized by comprising the following steps:

2. The preparation method of the quasi-double network hydrogel according to claim 1, wherein the mass ratio of the sodium alginate to the acrylamide is 1 (4-10).

3. The method for preparing quasi-double network hydrogel according to claim 1, wherein the mass ratio of ethylene glycol to water is (0.27-1.08): 7.

4. The method of claim 1, wherein the chloride salt comprises at least one of potassium chloride, sodium chloride, or lithium chloride.

5. The method for preparing quasi-double network hydrogel according to claim 4, wherein the mass ratio of the chloride salt to the water is (0.1-1): 28.

6. The method for preparing quasi-double network hydrogel according to claim 1, wherein the initiator is ammonium persulfate, the cross-linking agent is N, N ' -methylene bisacrylamide, and the co-initiator is N, N, N ', N ' -tetramethylethylenediamine.

7. The preparation method of the quasi-double network hydrogel according to claim 6, wherein the mass ratio of the ammonium persulfate to the acrylamide is 1:100, the mass ratio of the N, N ' -methylene bisacrylamide to the acrylamide is 0.0006:1, and the amount of the N, N, N ', N ' -tetramethylethylenediamine is 6.25 μ L/1g of acrylamide.

8. A quasi-double network hydrogel prepared by the method of any one of claims 1 to 7.

9. A quasi-double network hydrogel device comprising the quasi-double network hydrogel of claim 8 and a lead connected to the quasi-double network hydrogel.

10. Use of the quasi-dual network hydrogel device of claim 9 in a stress and electrical signal acquisition device.