A tin selenide - double network hydrogel and its preparation method and application

Abstract

The present invention provides a tin selenide - double - network hydrogel, its preparation method and application. The tin selenide - double - network hydrogel comprises a double - network hydrogel matrix, tin selenide and cationic salt compounds encapsulated in the double - network hydrogel matrix; the double - network hydrogel matrix comprises a first network polymer and a second network polymer crosslinked with each other. In the present invention, the tin selenide - double - network hydrogel adopts a double - network structure and incorporates tin selenide at the same time, so that the tin selenide - double - network hydrogel has stable mechanical properties, reversible stretchability and good anti - fatigue performance, can maintain stable electronic sensing performance, has good electrical conductivity and piezoelectric ion sensing performance, and can achieve self - powered sensing without relying on external power equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogel sensors, and particularly relates to a tin selenide - double network hydrogel composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Flexible and stretchable electronic sensing devices have compliance similar to biological systems and can adapt to complex interfaces of the human body or the surrounding environment, and have received increasing attention in the fields of artificial skin, soft robots, and actuators. As the largest organ of the human body, human skin is directly exposed to the external environment and provides a large number of important physiological and biochemical signals closely related to human health conditions. Effectively obtaining multifunctional physiological signals non - invasively through the skin provides an efficient and convenient way for realizing daily health monitoring, clinical disease diagnosis, and treatment, and has broad application prospects.

[0003] Among them, sensor arrays that simulate human skin have become a current research hotspot, and such a system can achieve real - time interaction of adapted mechanical properties and electronic information. In the process of constructing and mimicking natural skin, ionic skin has shown excellent advantages, mainly because most biological systems are based on the movement of ions. For example, the somatosensory network of the human body relies on ionic current to sense, transmit, and process tactile information. When this type of hydrogel is subjected to an external force, the pressure is converted into an ionic current, forming a piezoelectric ionic skin. By designing the hydrogel so that anions and cations have different mobilities, when the hydrogel is squeezed, an ionic gradient is generated, thereby generating a voltage. This phenomenon also implies a path to a bionic sensory interface, which is of great significance for non - invasively receiving physiological signals to achieve daily health monitoring.

[0004] However, existing flexible hydrogel sensors need to rely on external power instruments, etc. to maintain stable signal output during operation, which limits their application. For example, CN114350080A discloses a hydrogel sensor and a preparation method thereof. The preparation method includes: (1) pouring a hydrogel precursor solution into a closed reaction pool containing a micro - structure mold and polymerizing for 20 - 28 hours; (2) soaking the product obtained in step (1) in a cleaning solution for 1 - 3 days; (3) cleaning the product obtained in step (2), drying the surface, cutting it, and then mounting conductive copper foils on its two surfaces to assemble a hydrogel sensor. The hydrogel sensor needs to form a sensor with copper foils, and its application is limited.

[0005] Therefore, developing a hydrogel material that can achieve self - powered sensing without relying on external power instruments, etc., and has stable mechanical properties, biocompatibility, good electrical conductivity, and piezoelectric ionic sensing performance is an urgent problem to be solved in this field. Summary of the Invention

[0006] Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a tin selenide - double network hydrogel, its preparation method and application. The tin selenide - double network hydrogel is rich in water, has stable mechanical properties, reversible stretchability, anti - fatigue property, good biocompatibility, good electrical conductivity and piezoelectric ion sensing performance. Under the action of external forces, such as during stretching and compression, the anions and cations inside the hydrogel have different mobilities, thereby generating voltage / current. The electrical signal changes with the loading condition of the hydrogel itself, realizing flexible sensing performance for motion monitoring, and without the need to rely on external power equipment, that is, self - powered sensing can be achieved, greatly improving the convenience of application.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a tin selenide - double network hydrogel, which includes a double network hydrogel matrix and tin selenide and cationic salt compounds encapsulated in the double network hydrogel matrix; the double network hydrogel matrix includes a first network polymer and a second network polymer cross - linked with each other.

[0009] In the present invention, the tin selenide - double network hydrogel uses the first network polymer as the internal network skeleton of the hydrogel, and then fills it with the second network polymer, so that the double network hydrogel has good mechanical stability and excellent performance in stretchability, reversible stretchability and fatigue resistance; and incorporating tin selenide (SnSe) nanosheets into the hydrogel matrix will not even reduce its mechanical stability, but even improve it; and the tin selenide - double network hydrogel composite material can maintain stable resistance sensing performance. When deformed by external forces (such as extrusion), the internal network of the hydrogel deforms, and the anions and cations in the network move violently, making the anions and cations have different mobilities, generating an electric field, and then generating current and voltage signals, realizing piezoelectric ion sensing performance, and the hydrogel can achieve self - powered sensing without relying on external power equipment.

[0010] The preparation raw materials of the first network polymer include a first polymerization monomer, a first cross - linker and a first initiator.

[0011] Preferably, the first polymerization monomer includes 2 - acrylamide - 2 - methylpropanesulfonic acid and acrylamide.

[0012] Preferably, the mass ratio of 2-acrylamido-2-methylpropanesulfonic acid to acrylamide is (0.2 to 3):1, and can be, for example, 0.22:1, 0.24:1, 0.26:1, 0.28:1, 0.3:1, 0.32:1, 0.34:1, 0.36:1, 0.38:1, 0.4:1, 0.44:1, 0.48:1, 0.5:1, 0.52:1, 0.55:1, 0.58:1, 0.6:1, 0.62:1, 0.65:1, 0.68:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.15:1, 1.2:1, 1.25:1, 1.3:1, 1.35:1, 1.4:1, 1.45:1, 1.5:1, 1.55:1, 1.6:1, 1.65:1, 1.7:1, 1.75:1, 1.8:1, 1.85:1, 1.9:1, 1.95:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, etc., and more preferably (1 to 3):1.

[0013] Preferably, the first crosslinking agent includes N,N'-methylenebisacrylamide.

[0014] Preferably, the molar ratio of the first crosslinking agent to the first polymerization monomer is 1:(40 to 60), and can be, for example, 1:42, 1:44, 1:46, 1:48, 1:50, 1:52, 1:54, 1:56, 1:58, etc.

[0015] Preferably, the first initiator includes at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl phenylphosphonic acid ethyl ester, methyl benzoylformate, or benzoin dimethyl ether.

[0016] Preferably, the mass ratio of the first initiator to the first polymerization monomer is 1:(5 to 15), and can be, for example, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, etc.

[0017] Preferably, the raw materials for preparing the second network polymer include a second polymerization monomer, a second crosslinking agent, and a second initiator.

[0018] Preferably, the second polymerization monomer includes acrylamide.

[0019] Preferably, the second crosslinking agent includes polyethylene glycol diacrylate.

[0020] Preferably, the molar ratio of the second crosslinking agent to the second polymerization monomer is (0.1 - 0.5):100, for example, it can be 0.12:100, 0.14:100, 0.16:100, 0.18:100, 0.2:100, 0.22:100, 0.24:100, 0.26:100, 0.28:100, 0.3:100, 0.32:100, 0.34:100, 0.36:100, 0.38:100, 0.4:100, 0.42:100, 0.44:100, 0.46:100, 0.48:100, etc.

[0021] Preferably, the second initiator includes at least one of 2 - hydroxy - 2 - methyl - 1 - phenyl - 1 - propanone, 1 - hydroxycyclohexyl phenyl ketone, 2,4,6 - trimethylbenzoyl - diphenylphosphine oxide, ethyl 2,4,6 - trimethylbenzoyl phenylphosphonate, methyl benzoylformate or benzoin dimethyl ether.

[0022] Preferably, the mass ratio of the second initiator to the second monomer is 1:(30 - 50), for example, it can be 1:35, 1:40, 1:45, etc.

[0023] Preferably, the mass ratio of tin selenide to the first polymerization monomer is (0.25 - 5):100, for example, it can be 0.28:100, 0.3:100, 0.35:100, 0.4:100, 0.45:100, 0.5:100, 0.75:100, 0.8:100, 0.85:100, 0.9:100, 0.92:100, 0.96:100, 0.98:100, 1:100, 1.25:100, 1.5:100, 1.75:100, 2:100, 2.25:100, 2.5:100, 2.75:100, 3:100, 3.25:100, 3.5:100, 3.75:100, 4:100, 4.25:100, 4.5:100, 4.75:100, etc.

[0024] In the present invention, if the content of tin selenide relative to the first polymerization monomer is too high, the mechanical stability is poor; if it is too low, the resistance sensing and piezoelectric ion sensing performances are poor.

[0025] Preferably, the tin selenide is tin selenide nanosheets.

[0026] Preferably, the cationic salt compound includes a combination of potassium ferricyanide, potassium ferrocyanide and sodium chloride.

[0027] Preferably, the ratio of the total molar amount of potassium ferricyanide and potassium ferrocyanide to the molar amount of sodium chloride in the cationic salt compound is 1:(10 - 20), for example, it can be 1:12, 1:14, 1:16, 1:18, etc.; the molar ratio of potassium ferricyanide to potassium ferrocyanide is 1:(0.9 - 1.1), for example, it can be 1:0.95, 1:1, 1:1.05, etc.

[0028] In a second aspect, the present invention provides a method for preparing tin selenide - double network hydrogel according to the first aspect, and the preparation method includes the following steps:

[0029] (1) Mix the first polymerization monomer, the first cross - linker, the first initiator, tin selenide and the solvent evenly, and carry out a polymerization reaction to obtain a colloid;

[0030] (2) Mix and swell the colloid obtained in step (1) with the second polymerization monomer, the second cross - linker, the second initiator and the solvent, carry out a polymerization reaction, and perform a solvent exchange to obtain the tin selenide - double network hydrogel.

[0031] Preferably, the concentration of tin selenide in the solvent in step (1) is 0.5 - 10 mg / mL, for example, it can be 0.6 mg / mL, 0.8 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL, 5 mg / mL, 5.5 mg / mL, 6 mg / mL, 6.5 mg / mL, 7 mg / mL, 7.5 mg / mL, 8 mg / mL, 8.5 mg / mL, 9 mg / mL, 9.5 mg / mL, etc.

[0032] Preferably, the mixing time in step (1) is 10 - 30 min, for example, it can be 15 min, 20 min, 25 min, etc.

[0033] Preferably, the polymerization reaction in step (1) is carried out under ultraviolet lamp irradiation, and the polymerization reaction time is 10 - 30 min, for example, it can be 15 min, 20 min, 25 min, etc.

[0034] Preferably, the swelling in step (2) is carried out under light - shielding conditions, and the swelling time is 20 - 48 h, for example, it can be 22 h, 24 h, 26 h, 28 h, 30 h, 34 h, 38 h, 40 h, 42 h, 44 h, 46 h, etc.

[0035] Preferably, the polymerization reaction in step (2) is carried out under ultraviolet lamp irradiation, and the polymerization reaction time is 10 - 30 min, for example, it can be 15 min, 20 min, 25 min, etc.

[0036] Preferably, the solvent exchange method includes: immersing the gel obtained from the polymerization reaction in step (2) into a mixed solution of potassium ferricyanide, potassium ferrocyanide, and sodium chloride to obtain the tin selenide - double network hydrogel.

[0037] As a preferred technical solution of the present invention, the preparation method includes:

[0038] (1) Mix the first polymerization monomer, the first cross - linker, the first initiator, tin selenide, and a solvent for 10 - 30 min, and then carry out a polymerization reaction for 10 - 30 min under ultraviolet light irradiation to obtain a colloid.

[0039] (2) Mix and swell the colloid obtained in step (1) with the second polymerization monomer, the second cross - linker, the second initiator, and a solvent in the dark for 20 - 48 h. Subsequently, carry out a polymerization reaction for 10 - 30 min under ultraviolet light irradiation, and then immerse the obtained gel into a mixed solution of potassium ferricyanide, potassium ferrocyanide, and sodium chloride for solvent exchange to obtain the tin selenide - double network hydrogel.

[0040] In the present invention, in the preparation method, the mass ratio of the second polymerization monomer to the first polymerization monomer input is 1:(0.8 - 1.6), for example, it can be 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, etc.

[0041] In the third aspect, the present invention provides a self - powered flexible hydrogel sensor based on piezoelectric ion sensing performance. The material of the self - powered flexible hydrogel sensor includes the tin selenide - double network hydrogel as described in the first aspect.

[0042] The numerical ranges described in the present invention not only include the above - listed point values, but also include any point values between the above - mentioned numerical ranges that are not listed. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range.

[0043] Compared with the prior art, the beneficial effects of the present invention are:

[0044] The present invention provides a tin selenide - double network hydrogel. The tin selenide - double network hydrogel adopts a double - network structure and incorporates both tin selenide and cationic salt compounds, enabling the tin selenide - double network hydrogel to have stable mechanical properties, good reversible stretchability and fatigue resistance, be able to maintain stable electronic sensing performance, have good electrical conductivity and piezoelectric ion sensing performance, and can achieve self - powered sensing without relying on external power equipment. Description of the Drawings

[0045] Figure 1 It is a scanning electron micrograph of the tin selenide - double network hydrogel provided for Example 1.

[0046] Figure 2 Stress-strain curves of the tin selenide-double network hydrogels provided for Examples 1 and 2, and the double network hydrogel provided for Comparative Example 2 during stretching to fracture;

[0047] Figure 3 Stress-strain curves of the tin selenide-double network hydrogels provided for Examples 1 and 2, and the double network hydrogel provided for Comparative Example 2 during reversible stretching;

[0048] Figure 4 Stress curve of the tin selenide-double network hydrogel provided for Example 1 during cyclic stretching;

[0049] Figure 5 Internal resistance change diagram of the tin selenide-double network hydrogel provided for Example 1 during stretching and releasing;

[0050] Figure 6 Schematic diagram of the piezoelectric effect generated by the tin selenide-double network hydrogel provided by the present invention;

[0051] Figure 7 Schematic diagram for proving that the tin selenide-double network hydrogel provided by the present invention can generate a piezoelectric effect to light up a light-emitting diode;

[0052] Figure 8 Voltage change diagram collected for the tin selenide-double network hydrogel provided for Example 1 during the process of moving load; where Figure 8 a is a schematic diagram of the test location, Figure 8 b is the voltage change diagram during the test process;

[0053] Figure 9 Voltage signal diagram generated by the tin selenide-double network hydrogel provided for Example 1 under a stressed state;

[0054] Figure 10 Current signal diagram generated by the tin selenide-double network hydrogel provided for Example 1 under a stressed state;

[0055] Figure 11 Schematic diagram of the sensing monitoring and related signal acquisition of the tin selenide-double network hydrogel provided for Example 1 during the finger bending movement; where Figure 11 a is the schematic diagram of the sensing monitoring, Figure 11 b is the voltage change diagram during the finger bending movement;

[0056] Figure 12 Signal acquisition situation of the tin selenide-double network hydrogel provided for Example 1 at the maximum finger bending amplitude; where Figure 12 a is the voltage change diagram corresponding to the maximum finger bending amplitude for acquisition,Figure 12 b is the current change graph collected when the finger bends to the maximum amplitude;

[0057] Figure 13 It is a schematic diagram of the sensing monitoring and related signal acquisition during the fist clenching movement provided by Example 1 for the tin selenide - double network hydrogel; among them Figure 13 a is the schematic diagram of the sensing monitoring, Figure 13 b is the voltage change graph during the fist clenching movement; Figure 13 c is the current change graph during the fist clenching movement. Detailed implementation manners

[0058] The technical solutions of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the described embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0059] Example 1

[0060] This example provides a tin selenide - double network hydrogel, which includes a double network hydrogel matrix and tin selenide, K3Fe(CN)6, K4Fe(CN)6, and NaCl wrapped in the double network hydrogel matrix; the double network hydrogel matrix includes a first network polymer and a second network polymer crosslinked with each other; the preparation raw materials of the first network polymer include 2 - acrylamide - 2 - methylpropane sulfonic acid (AMPS), acrylamide (AM), N,N'-methylenebisacrylamide (BIS), and 2 - hydroxy - 2 - methyl - 1 - phenyl - 1 - propanone (HMPP); the mass ratio of AMPS to AM is 2:1; the molar ratio of BIS to the total molar amount of AMPS and AM is 2:100, the mass ratio of HMPP to the total mass of AMPS and AM is 1:11.79, and the mass ratio of tin selenide to the total mass of AMPS and AM is 0.5:100; the preparation raw materials of the second network polymer include AM, polyethylene glycol diacrylate (PEGDA), and HMPP; the molar ratio of PEGDA to AM is 0.2:100, and the mass ratio of HMPP to AM is 1:41.67; the ratio of the total molar amount of K3Fe(CN)6 and K4Fe(CN)6 to the molar amount of sodium chloride is 1:15, and the molar ratio of K3Fe(CN)6 to K4Fe(CN)6 is 1:1.

[0061] This example provides a preparation method for the tin selenide - double network hydrogel, including the following steps:

[0062] (1) According to the formulation amount, mix 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, N,N'-methylenebisacrylamide, 2-hydroxy-2-methyl-1-phenyl-1-propanone and an aqueous solution of SnSe nanosheets and stir for 20 min to fully dissolve them, so that the total concentration of 2-acrylamido-2-methylpropanesulfonic acid and acrylamide is 16.5 wt%, the concentration of HMPP is 1.4 wt%, and the concentration of SnSe nanosheets is 1 mg / mL. Subsequently, irradiate from the bottom with an ultraviolet lamp for 20 min to polymerize it into a gel and obtain a colloid;

[0063] (2) Mix AM (12.5 wt%), PEGDA (0.2 mol%), and HMPP (0.3 wt%) with water to obtain a mixed solution; immerse the colloid obtained in step (1) in the mixed solution, keep it in the dark and stand still for 24 hours until it reaches swelling equilibrium; take out the colloid that has reached swelling equilibrium, dry the residual solution on the surface, and irradiate it with an ultraviolet lamp for 20 min to polymerize it into a gel to obtain a hydrogel; immerse the hydrogel in a mixed solution of 0.2 M [K3Fe(CN)6 / K4 F Fe(CN)6] and 3 M NaCl for solvent exchange, where the molar ratio of Fe(CN)6 3- to Fe(CN)6 4- is 1:1 to obtain the tin selenide-binetwork hydrogel.

[0064] The morphology of the tin selenide-binetwork hydrogel obtained in Example 1 was characterized by scanning electron microscopy, and the results are as Figure 1 shown. It can be seen that the prepared binetwork hydrogel matrix presents a porous network structure, and the SnSe nanosheets are uniformly wrapped in the hydrogel matrix.

[0065] Example 2

[0066] This example provides a tin selenide-binetwork hydrogel, which is only different from Example 1 in that in the preparation method, the concentration of SnSe nanosheets in step (1) is 2 mg / mL, that is, the mass ratio of tin selenide to the total mass of AMPS and AM is 1:100, and the types, amounts, ratios and process parameters of other raw materials are the same as those in Example 1.

[0067] Example 3

[0068] This embodiment provides a tin selenide - double - network hydrogel, which includes a double - network hydrogel matrix and tin selenide, K3Fe(CN)6, K4Fe(CN)6, and NaCl encapsulated in the double - network hydrogel matrix; the double - network hydrogel matrix includes a first network polymer and a second network polymer cross - linked with each other; the raw materials for preparing the first network polymer include 2 - acrylamido - 2 - methylpropane sulfonic acid (AMPS), acrylamide (AM), N,N'-methylenebisacrylamide (BIS), and 2 - hydroxy - 2 - methyl - 1 - phenyl - 1 - propanone (HMPP); the mass ratio of AMPS to AM is 1.88:1; the molar ratio of BIS to the total molar amount of AMPS and AM is 2:90, the mass ratio of HMPP to the total mass of AMPS and AM is 1:12.5, and the mass ratio of tin selenide to the total mass of AMPS and AM is 0.75:100; the raw materials for preparing the second network polymer include AM, polyethylene glycol diacrylate (PEGDA), and HMPP; the molar ratio of PEGDA to AM is 0.23:100, the mass ratio of HMPP to AM is 1:38; the ratio of the total molar amount of K3Fe(CN)6 and K4Fe(CN)6 to the molar amount of sodium chloride is 1:15, and the molar ratio of K3Fe(CN)6 to K4Fe(CN)6 is 1:1.

[0069] This embodiment provides a preparation method of the tin selenide - double - network hydrogel composite material. In step (1), the total concentration of 2 - acrylamido - 2 - methylpropane sulfonic acid and acrylamide is 16.5 wt%, the types of other raw materials remain unchanged, and the contents are adjusted according to the ratio. The process parameters are the same as those in Example 1.

[0070] Example 4

[0071] This embodiment provides a tin selenide - double - network hydrogel, which includes a double - network hydrogel matrix and tin selenide, K3Fe(CN)6, K4Fe(CN)6, and NaCl encapsulated in the double - network hydrogel matrix; the double - network hydrogel matrix includes a first - network polymer and a second - network polymer cross - linked with each other; the raw materials for preparing the first - network polymer include 2 - acrylamido - 2 - methylpropanesulfonic acid (AMPS), acrylamide (AM), N,N'-methylenebisacrylamide (BIS), and 2 - hydroxy - 2 - methyl - 1 - phenyl - 1 - propanone (HMPP); the mass ratio of AMPS to AM is 1.59:1; the molar ratio of BIS to the total molar amount of AMPS and AM is 2:110, the mass ratio of HMPP to the total mass of AMPS and AM is 1:10.5, and the mass ratio of tin selenide to the total mass of AMPS and AM is 0.9:100; the raw materials for preparing the second - network polymer include AM, polyethylene glycol diacrylate (PEGDA), and HMPP; the molar ratio of PEGDA to AM is 0.31:100, and the mass ratio of HMPP to AM is 1:45; the ratio of the total molar amount of K3Fe(CN)6 and K4Fe(CN)6 to the molar amount of sodium chloride is 1:15, and the molar ratio of K3Fe(CN)6 to K4Fe(CN)6 is 1:1.

[0072] This embodiment provides a preparation method of the tin selenide - double - network hydrogel. In step (1), the total concentration of 2 - acrylamido - 2 - methylpropanesulfonic acid and acrylamide is 16.5 wt%, the types of other raw materials remain unchanged, and the contents are adjusted according to the ratio. The process parameters are the same as those in Example 1.

[0073] Example 5

[0074] This embodiment provides a tin selenide - double - network hydrogel, which is different from Example 1 only in that, in the raw materials for preparing the first - network polymer, the mass ratio of AMPS to AM is 0.1:1, and the types, dosages, ratios, and process parameters of other raw materials are the same as those in Example 1.

[0075] Example 6

[0076] This embodiment provides a tin selenide - double - network hydrogel, which is different from Example 1 only in that, in the raw materials for preparing the first - network polymer, the mass ratio of AMPS to AM is 4:1, and the types, dosages, ratios, and process parameters of other raw materials are the same as those in Example 1.

[0077] Example 7

[0078] This example provides a tin selenide - double network hydrogel, which is only different from Example 1 in that in the preparation raw materials of the first network polymer, the total amount of monomers remains unchanged, there is no AM, and the types, dosages, ratios and process parameters of other raw materials are the same as those in Example 1.

[0079] Example 8

[0080] This example provides a tin selenide - double network hydrogel, which is only different from Example 1 in that in the preparation raw materials of the first network polymer, the cross - linker is PEGDA of equal mass, and in the preparation raw materials of the second network polymer, the cross - linker is BIS of equal mass, and the types, dosages, ratios and process parameters of other raw materials are the same as those in Example 1.

[0081] Example 9

[0082] This example provides a tin selenide - double network hydrogel, which is only different from Example 1 in that in the preparation raw materials of the first network polymer, the dosage of the cross - linker is increased so that the molar ratio of it to the first polymerization monomer is 1:30, and in the preparation raw materials of the second network polymer, the dosage of the cross - linker is reduced so that the molar ratio of it to the second polymerization monomer is 0.05:100, and the types, dosages, ratios and process parameters of other raw materials are the same as those in Example 1.

[0083] Example 10

[0084] This example provides a tin selenide - double network hydrogel, which is only different from Example 1 in that in the preparation raw materials of the first network polymer, the dosage of the cross - linker is reduced so that the molar ratio of it to the first polymerization monomer is 1:70, and in the preparation raw materials of the second network polymer, the dosage of the cross - linker is increased so that the molar ratio of it to the second polymerization monomer is 0.6:100, and the types, dosages, ratios and process parameters of other raw materials are the same as those in Example 1.

[0085] Example 11

[0086] This example provides a tin selenide - double network hydrogel, which is only different from Example 1 in that in the cationic salt compound, the total molar amount of K3Fe(CN)6 and K4Fe(CN)6 remains unchanged, there is no K3Fe(CN)6, and the types, dosages, ratios and process parameters of other raw materials are the same as those in Example 1.

[0087] Comparative Example 1

[0088] This comparative example provides a molybdenum disulfide - double network hydrogel, which is only different from Example 1 in that the tin selenide is replaced with molybdenum disulfide of equal mass, and the types, dosages, ratios and process parameters of other raw materials are the same as those in Example 1.

[0089] Comparative Example 2

[0090] This comparative example provides a double-network hydrogel, which is only different from Example 1 in that there is no tin selenide in the double-network hydrogel, and the types, dosages, ratios of other raw materials and process parameters are the same as those in Example 1.

[0091] Performance Test

[0092] (1) Mechanical Properties

[0093] A. Stress-Strain Curve

[0094] Cut the double-network hydrogel materials provided in the examples and comparative examples into appropriate sizes (thickness 1 mm, width 10 mm, and keep the initial length during stretching between the clamps as 10 mm), and stretch them at a stretching speed of 3 mm / min until the sample is completely broken, and record the stress and strain changes during the stretching to breakage process. The stress-strain curves of the tin selenide-double-network hydrogels provided in Example 1 and 2 and the double-network hydrogel provided in Comparative Example 2 are as Figure 2 shown; the values of the fracture strain and fracture stress are shown in Table 1.

[0095] B. Reversible Stretchability

[0096] Perform a loading-unloading test on the double-network hydrogel materials provided in Example 1, 2 and Comparative Example 2, and record the stress and strain changes during the reversible stretching process. The results are as Figure 3 shown. It can be seen that the tin selenide-double-network hydrogel provided by the present invention exhibits medium-range reversible stretchability, and the residual strain under load can be ignored.

[0097] C. Fatigue Resistance

[0098] Taking Example 1, 5, 6, Comparative Example 1 and 2 as examples, stretch the tin selenide-double-network hydrogel to a strain of 30%, and perform a cyclic stretching test, and record the stress required for different numbers of cycles. The test results of Example 1 are as Figure 4 shown, and the test data results of Example 1, 5, 6, Comparative Example 1 and 2 are shown in Table 2.

[0099] (2) Resistance Sensing Performance

[0100] Take a selenium tin double-network hydrogel of appropriate size (5 cm in length, 1 cm in width, and 1 mm in thickness), connect wires at both ends, and connect the wires to an LCR digital bridge. Use an electronic universal testing machine to perform multiple stretching and releasing operations on the hydrogel, record the change in the internal resistance value during the stretching and releasing process of the selenium tin double-network hydrogel under different strains, and record the value of (R - R0) / R0, where R0 represents the initial resistance value and R represents the resistance value that changes in real time. Among them, the change in (R - R0) / R0 of the selenium tin double-network hydrogel provided in Example 1 is as shown in Figure 5 shown, indicating that the selenium tin double-network hydrogel provided by the present invention can still maintain stable resistance sensing in different strain ranges and repeated tests. Adding SnSe can, to a certain extent, improve the linear relationship between the tensile strength and resistance sensing. The change in (R - R0) / R0 of the materials provided in Example 1, Example 2, and Comparative Example 2 under different cycle numbers and strain conditions is shown in Table 3. The change in (R - R0) / R0 of the double-network hydrogels provided in Example 3, Example 4, Example 11, and Comparative Example 1 under a strain of 30% and different cycle numbers is shown in Table 4.

[0101] (3) Piezoelectric ion sensing performance

[0102] Since the selenium tin double-network hydrogel is immersed in a sufficient amount of electrolyte aqueous solution during the preparation process and sufficient solvent exchange is carried out, a large number of ions penetrate into the network structure inside the hydrogel during the immersion process. As shown in Figure 6 , when the hydrogel is deformed by an external force (such as extrusion), the internal network of the gel deforms, and the positive and negative ions in the network move violently, resulting in different mobilities of anions and cations, generating an electric field, and then generating current and voltage signals. The following experiment was carried out using the selenium tin double-network hydrogel provided in Example 1:

[0103] A. Verification of piezoelectric ion sensing phenomenon

[0104] Take a piece of selenium tin double-network hydrogel, connect wires, and connect the other ends of the wires to both ends of an LED light-emitting diode. After pressing the hydrogel with a finger, due to the existence of the piezoelectric effect and the generation of current, the LED light-emitting diode is lit, as shown in Figure 7 shown. It can be seen that after pressing with a finger, the light-emitting diode is lit, indicating that the selenium tin double-network hydrogel has a piezoelectric ion sensing phenomenon.

[0105] B. Realization of test positioning

[0106] During the generation of the piezoelectric effect, the closer the pressure application position is to the signal acquisition site, the stronger the signal, and the signal acquisition sites at both ends of the hydrogel will collect signals with opposite signs. Therefore, during the test, by moving the position of the hydrogel under the load device, a series of changing signals can be collected. The test results are as Figure 8 shown in Figure 8 Figure b,

[0107] C. Voltage signal

[0108] Take a suitable size of tin selenide - double network hydrogel (5 cm long, 1 cm wide, 1 mm thick), connect wires at both ends, connect the wires to an oscilloscope, apply a certain degree of external force to the hydrogel, and record the generation and change of the voltage signal. The results are as Figure 9 shown. As Figure 9 can be seen, under the action of external force, the hydrogel provided by the present invention will generate a voltage signal of about 140 mV, and the signal stability can still be maintained in repeated tests.

[0109] D. Current signal

[0110] Take a suitable size of tin selenide - double network hydrogel (5 cm long, 1 cm wide, 1 mm thick), connect wires at both ends, connect the wires to a current signal acquisition device, place weights of different weights (0.5, 1, 1.5 kg) on the hydrogel, and record the generation and change of the current signal. The results are as Figure 10 shown. It can be seen that the tin selenide - double network hydrogel provided by the present invention can generate a stable current under different pressures.

[0111] (4) Self - sensing performance

[0112] The mechanical stability and piezoelectric properties of the tin selenide - double network hydrogel composite have been verified. Therefore, in the present invention, VHB tape is designed to encapsulate this hydrogel. The VHB tape can adhere well to the human skin surface to realize a self - powered flexible sensor that can monitor human movements (such as finger bending).

[0113] A. Finger bending movement

[0114] The schematic diagram of sensing monitoring during the finger bending movement and the relevant signal acquisition situation are as Figure 11 and Figure 2 shown. Among them, Figure 11 Figure a is the schematic diagram of finger sensing monitoring; Figure 11 Figure b is the change of voltage with the finger bending amplitude; Figure 12 Figure a is the change of voltage at different times when the finger bends to the maximum amplitude; Figure 12b shows the current variation at different times when the finger is bent to the maximum amplitude;

[0115] As can be seen from Figure 11 b, when the finger is bent at different amplitudes (such as 30°, 60°, 90°), the corresponding voltage signal values also change, and the greater the bending amplitude, the greater the voltage; As can be seen from Figure 12 it can be seen that when the finger is bent to the maximum amplitude, a voltage change of about 12 mV and a current change amplitude of about 3 μA can be collected, indicating that the tin selenide - double network hydrogel provided by the present invention has self - sensing performance.

[0116] B. Fist - clenching movement

[0117] The schematic diagram of sensing monitoring and the related signal acquisition during the fist - clenching movement are as shown in Figure 13 shown, where Figure 13 a is the schematic diagram of fist - clenching sensing monitoring; Figure 13 b and 13c are respectively the voltage signal (b) and current signal (c) collected during the fist - clenching process. As can be seen from Figure 13 it can be seen that during the fist - clenching process, a voltage change of about 12 mV and a current change amplitude of about 3 μA can also be collected, indicating that the tin selenide - double network hydrogel provided by the present invention has self - sensing performance.

[0118] Table 1

[0119]

[0120]

[0121] As can be seen from Table 1, when a small amount of SnSe is introduced, the change in the fracture strain of the double - network hydrogel can be ignored, but the fracture stress is significantly enhanced; and from Examples 1 and 2, it can be seen that when the SnSe content is further increased, the fracture stress of the double - network hydrogel decreases, but it is still higher than that of the double - network hydrogel provided in Comparative Example 2, indicating that adding SnSe can significantly improve the mechanical properties of the double - network hydrogel.

[0122] And from Examples 1 and Examples 5 - 7, it can be seen that the first - network polymer is not a specific combination or ratio, and the fracture stress and strain of the double - network hydrogel decrease; from Examples 1 and Examples 8 - 10, it can be seen that for cross - linkers with non - specific dosages and types, the fracture stress and fracture strain of the double - network hydrogel decrease.

[0123] As can be seen from the comparison between Example 1 and Comparative Example 1, when other materials are used to replace tin selenide, the fracture stress and fracture strain of the double - network hydrogel decrease, and the mechanical properties are poor.

[0124] Table 2

[0125]

[0126] As can be seen from Table 2, for the tin selenide - double network hydrogel provided by the present invention, when the strain is 30% and after 600 cycles, the dissipated energy still remains stable at a low level, demonstrating its persistent anti - fatigue performance; while for the technical solution not preferred by the present invention, its anti - fatigue performance is poor.

[0127] Table 3

[0128]

[0129]

[0130] Table 4

[0131] Number of cycles Example 3 Example 4 Example 11 Comparative Example 1 1 43.15 42.85 32.94 36.39 2 42.83 42.64 32.22 35.77 3 42.51 42.33 31.39 35.05 4 42.36 41.91 30.71 34.59 5 41.92 41.75 29.71 34.06

[0132] As can be seen from Table 3 and Table 4, the tin selenide - double network hydrogel provided by the present invention can still maintain stable resistive sensing in different strain ranges and repeated tests; adding SnSe can, to a certain extent, improve the linear relationship between tensile strength and resistive sensing; when SnSe is replaced by other materials, or the cationic salt compounds are not in a specific combination, the resistive sensing performance of the double network hydrogel is poor.

[0133] In summary, the tin selenide - double network hydrogel provided by the present invention, through specific structural design and raw material selection, is rich in water, has stable mechanical properties, good reversible stretchability, anti - fatigue property and biocompatibility, has good electrical conductivity and piezo - ionic sensing performance, can generate electrical signals under the action of external forces, and can be used as a flexible sensor for motion monitoring. Moreover, it does not require external power equipment, that is, it can achieve self - powered sensing, greatly improving the convenience of application.

[0134] The applicant declares that the above - mentioned is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A tin selenide - double network hydrogel, characterized in that, The tin selenide - double network hydrogel includes a double network hydrogel matrix, and tin selenide and cationic salt compounds encapsulated in the double network hydrogel matrix; The double network hydrogel matrix includes a first network polymer and a second network polymer crosslinked with each other; The preparation raw materials of the first network polymer include a first polymerization monomer, a first crosslinking agent, and a first initiator; The first polymerization monomer includes 2 - acrylamido - 2 - methylpropanesulfonic acid and acrylamide; The mass ratio of 2 - acrylamido - 2 - methylpropanesulfonic acid to acrylamide is (1 - 3):1; The preparation raw materials of the second network polymer include a second polymerization monomer, a second crosslinking agent, and a second initiator; The second polymerization monomer includes acrylamide; The cationic salt compounds include a combination of potassium ferricyanide, potassium ferrocyanide, and sodium chloride.

2. The tin selenide - double network hydrogel according to claim 1, wherein The first crosslinking agent includes N,N'-methylenebisacrylamide.

3. The tin selenide - double network hydrogel according to claim 1, wherein The molar ratio of the first crosslinking agent to the first polymerization monomer is 1:(40 - 60).

4. The tin selenide - double network hydrogel according to claim 1, characterized in that, The first initiator includes at least one of 2 - hydroxy - 2 - methyl - 1 - phenyl - 1 - propanone, 1 - hydroxycyclohexyl phenyl ketone, 2,4,6 - trimethylbenzoyl - diphenylphosphine oxide, ethyl 2,4,6 - trimethylbenzoyl phenylphosphinate, methyl benzoylformate, or benzoin dimethyl ether.

5. The tin selenide - double network hydrogel according to claim 1, characterized in that, The mass ratio of the first initiator to the first polymerization monomer is 1:(5 - 15).

6. The tin selenide - double network hydrogel according to claim 1, wherein, The second crosslinking agent includes polyethylene glycol diacrylate.

7. The tin selenide - double network hydrogel according to claim 1, characterized in that, The molar ratio of the second crosslinking agent to the second polymerization monomer is (0.1 - 0.5):

100.

8. The tin selenide - double network hydrogel according to claim 1, wherein, The second initiator includes at least one of 2 - hydroxy - 2 - methyl - 1 - phenyl - 1 - propanone, 1 - hydroxycyclohexyl phenyl ketone, 2,4,6 - trimethylbenzoyl - diphenylphosphine oxide, ethyl 2,4,6 - trimethylbenzoyl phenylphosphinate, methyl benzoylformate, or benzoin dimethyl ether.

9. The tin selenide - double network hydrogel according to claim 1, characterized in that, The mass ratio of the second initiator to the second monomer is 1:(30 - 50).

10. The tin selenide - double network hydrogel according to claim 1, characterized in that, The mass ratio of the tin selenide to the first polymerization monomer is (0.25 - 5):

100.

11. The tin selenide - double network hydrogel according to claim 1, characterized in that, The tin selenide is tin selenide nanosheets.

12. The tin selenide - double network hydrogel according to claim 1, wherein The ratio of the total molar amount of potassium ferricyanide and potassium ferrocyanide to the molar amount of sodium chloride in the cationic salt compounds is 1:(10 - 20), and the molar ratio of potassium ferricyanide to potassium ferrocyanide is 1:(0.9 - 1.1).

13. A preparation method of the tin selenide - double network hydrogel according to any one of claims 1 to 12, characterized in that, The preparation method includes the following steps: (1) Mix the first polymerization monomer, the first crosslinking agent, the first initiator, the tin selenide, and a solvent evenly, and carry out a polymerization reaction to obtain a colloid; (2) Mix and swell the colloid obtained in step (1) with the second polymerization monomer, the second crosslinking agent, the second initiator, and a solvent, carry out a polymerization reaction, and perform solvent exchange to obtain the tin selenide - double network hydrogel.

14. The preparation method according to claim 13, wherein The concentration of the tin selenide in the solvent in step (1) is 0.5 - 10 mg / mL.

15. The preparation method according to claim 13, characterized in that, The mixing time in step (1) is 10 - 30 min.

16. The preparation method according to claim 13, characterized in that, The polymerization reaction in step (1) is carried out under ultraviolet lamp irradiation, and the polymerization reaction time is 10 - 30 min.

17. The preparation method according to claim 13, characterized in that, The swelling in step (2) is carried out under light - shielding conditions, and the swelling time is 20 - 48 h.

18. The preparation method according to claim 13, wherein The polymerization reaction described in step (2) is carried out under ultraviolet lamp irradiation for 10 to 30 minutes.

19. The preparation method according to claim 13, wherein, The method of solvent exchange includes: immersing the gel obtained from the polymerization reaction in step (2) into a mixed solution of potassium ferricyanide, potassium ferrocyanide and sodium chloride to obtain the tin selenide - double network hydrogel.

20. The preparation method according to claim 13, wherein The preparation method includes: (1) Mix the first polymerization monomer, the first cross - linker, the first initiator, tin selenide with the solvent for 10 to 30 minutes, and then carry out a polymerization reaction for 10 to 30 minutes under ultraviolet lamp irradiation to obtain a colloid. (2) Mix and swell the colloid obtained in step (1) with the second polymerization monomer, the second cross - linker, the second initiator and the solvent in the dark for 20 to 48 hours. Subsequently, after carrying out a polymerization reaction for 10 to 30 minutes under ultraviolet lamp irradiation, immerse the obtained gel into a mixed solution of potassium ferricyanide, potassium ferrocyanide and sodium chloride for solvent exchange to obtain the tin selenide - double network hydrogel.

21. A self-powered flexible hydrogel sensor based on piezoelectric ion sensing performance, characterized in that, The material of the self - powered flexible hydrogel sensor includes the tin selenide - double network hydrogel as described in any one of claims 1 to 12.

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