Breathable ion skin preparation method and application

Abstract

The invention relates to the technical field of flexible sensors, and particularly discloses breathable ion skin which comprises water, a polymer, a liquid crystal and a conductive ion active substance. The material with unique soft elasticity is prepared by combining the orderly-oriented liquid crystal material and the polymer elastomer, the excellent adhesion stability can be kept under the cyclic load, and the stripping interface toughness is high. The composite fiber membrane of a liquid crystal elastomer core-ion skin shell structure is prepared through coaxial electrostatic spinning, the liquid crystal elastomer core provides good structural stability and adhesion stability, the ion skin shell provides good signal detection capacity, and meanwhile, the porous membrane structure prepared through electrostatic spinning has the ultrahigh water vapor permeability and can be used for preparing the composite fiber membrane of the liquid crystal elastomer core-ion skin shell structure. Sweat generated at the contact site of the ion skin and the human skin can be quickly volatilized, sweat accumulation is reduced, and the human skin does not have inflammatory response after the ion skin is worn for a long time.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible sensors, and in particular relates to a preparation method and application of breathable ion skin. Background Art

[0002] With the rapid development of intelligent monitoring technology, people's demand for wearable electronic products that can monitor human health in real time is increasing. Ionic skin has good skin-friendly performance, a large detection range, and high sensitivity, and can be widely used in wearable electronic device sensors. However, ionic skin sensors need to fit closely to the skin. When the thickness exceeds 500μm, the moisture permeability is hindered, and the water vapor transmission rate is generally less than 200g / m -2 d -1 , long-term wearing will increase the risk of sweat accumulation and inflammation.

[0003] To address these issues, researchers have proposed two solutions. One involves adding antimicrobial materials to inhibit bacterial growth on the ionic skin's surface. However, this approach doesn't address the root cause and doesn't provide long-term, effective antibacterial effects. Another approach involves designing a directional sweat-wicking structure. However, this type of design often compromises mechanical properties, making the ionic skin susceptible to damage. Therefore, achieving both superior breathability and high stability in the ionic skin remains a challenge. Summary of the Invention

[0004] To solve the above problems, the present invention provides a method for preparing breathable ionic skin and its application, which is achieved through the following technical solutions.

[0005] A method for preparing and applying breathable ionic skin, comprising the following components by weight percentage:

[0006] Water: 5-15wt%;

[0007] Polymer matrix: 35-55wt%;

[0008] Liquid crystal elastomer: 25-45wt%;

[0009] Ion-conducting active material: 10-20 wt%.

[0010] Furthermore, the polymer matrix is ​​selected from one or any combination of polyester, polyurethane, styrene-ethylene-butylene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, ethylene propylene rubber, and polyvinyl pyrrolidone.

[0011] Furthermore, the liquid crystal elastomer is formed by Michael addition reaction of electron-deficient olefin and nucleophilic reagent.

[0012] Furthermore, the electron-deficient olefin is selected from one or any combination of bisphenol A epoxy diacrylate, 4,4'-diphenyl diacrylate, 1,3-phenylenebis(methylene) diacrylate, and 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene.

[0013] Furthermore, the nucleophilic reagent is selected from one or any combination of 2-mercaptoethyl sulfide, 2-aminobenzenethiol, 1,6-hexanedithiol, 1,5-pentanedithiol, butanedithiol, and 2,2'-(1,2-ethanediyldioxy)bis(ethyl mercaptan).

[0014] Furthermore, the ion-conducting active substance is selected from one or any combination of acetylcholine chloride, betaine, N,N,N,N-tetramethylethylenediamine, N,N-dimethylglycine, N,N-dimethylaminoethyl acetate, and stachydrine.

[0015] Furthermore, a method for producing breathable ionic skin comprises the following steps:

[0016] S1. Preparation of liquid crystal elastomer: dissolve the electron-deficient olefin and polymer in a solvent, add a nucleophile and a diphenylamine catalyst, and react at room temperature for 8-16 hours;

[0017] S2. Preparation of ionic skin solution: dissolving the polymer and the ion-conducting active substance in a solvent and mixing them uniformly;

[0018] S3, coaxial electrospinning: using the product of step S1 as the core layer and the product of step S2 as the sheath layer, controlling the core-sheath spinning speed ratio to 1:4 to 2:1, applying a voltage of 10-12 kV to spin into a fiber membrane;

[0019] S4. Curing the obtained fiber membrane at 25-50% RH for 24-48 hours.

[0020] Furthermore, the solvent is N,N-dimethylformamide, tetrahydrofuran or dimethyl sulfoxide.

[0021] Furthermore, a breathable ionic skin flexible sensor is formed by printing flexible electrodes on the surface of the ionic skin.

[0022] Furthermore, the flexible electrode is any one of a silver nanowire conductive network or a carbon-based conductive ink.

[0023] The present invention has the beneficial effect of combining an ordered liquid crystal material with a polymer elastomer to produce a uniquely soft and elastic material that maintains excellent adhesion stability under cyclic loading and exhibits high toughness at the peeling interface. A composite fiber membrane with a liquid crystal elastomer core-ion skin shell structure is prepared by coaxial electrospinning. The liquid crystal elastomer core provides excellent structural and adhesion stability, while the ion skin shell provides excellent signal detection capabilities. Furthermore, the porous membrane structure produced by electrospinning exhibits an ultra-high water vapor permeability, which rapidly evaporates sweat generated at the contact point between the ion skin and human skin, reducing sweat accumulation. Long-term wearing of the ion skin results in no inflammatory reaction on the human skin. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the description of the specific implementation methods. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a schematic diagram of the breathable ion skin electrospun fiber membrane and fiber structure of the present invention;

[0026] Figure 2 TEM-EDS characterization of the breathable ion skin obtained in Example 1;

[0027] Figure 3 This is a signal diagram of the breathable ion skin sensor obtained in Example 1 detecting blinking action;

[0028] Figure 4 This is a signal diagram of the breathable ion skin sensor obtained in Example 2 detecting finger bending.

[0029] The reference numerals are as follows:

[0030] 1. Liquid crystal elastomer layer;

[0031] 2. Ionic skin layer. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] A breathable ionic skin comprising the following components by weight percentage:

[0034] Water: 5-15wt%;

[0035] Polymer matrix: 35-55wt%;

[0036] Liquid crystal elastomer: 25-45wt%;

[0037] Ion-conducting active material: 10-20 wt%.

[0038] Preferably, the polymer matrix is ​​selected from one or any combination of polyester, polyurethane, styrene-ethylene-butylene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, ethylene propylene rubber, and polyvinyl pyrrolidone.

[0039] Preferably, the liquid crystal elastomer is formed by a Michael addition reaction between an electron-deficient olefin and a nucleophile.

[0040] Preferably, the electron-deficient olefin is selected from one or any combination of bisphenol A epoxy diacrylate, 4,4'-diphenyl diacrylate, 1,3-phenylenebis(methylene) diacrylate, 1,3-phenylenebis(methylene) diacrylate, and 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene.

[0041] Preferably, the nucleophilic agent is selected from one or any combination of 2-mercaptoethyl sulfide, 2-aminobenzenethiol, 1,6-hexanedithiol, 1,5-pentanedithiol, butanedithiol, and 2,2'-(1,2-ethanediyldioxy)bis(ethanethiol).

[0042] Preferably, the ion-conducting active substance is selected from one or any combination of acetylcholine chloride, betaine, N,N,N,N-tetramethylethylenediamine, N,N-dimethylglycine, N,N-dimethylaminoethyl acetate, and stachydrine.

[0043] By combining ordered liquid crystal materials with polymer elastomers, a uniquely soft and elastic material is produced. It maintains excellent adhesion stability under cyclic loading and exhibits high peeling interface toughness. A composite fiber membrane with a liquid crystal elastomer core-ion skin shell structure is prepared through coaxial electrospinning. The liquid crystal elastomer core provides excellent structural and adhesion stability, while the ion skin shell provides excellent signal detection capabilities. Furthermore, the porous membrane structure produced by electrospinning has an ultra-high water vapor permeability, which can quickly evaporate sweat generated at the contact point between the ion skin and human skin, reducing sweat accumulation. After prolonged wear of the ion skin, the human skin does not experience an inflammatory reaction.

[0044] Example 1:

[0045] S1. Preparation of liquid crystal elastomer solution:

[0046] Bisphenol A epoxy diacrylate and polyurethane are added to a solvent and stirred evenly. 2-mercaptoethyl sulfide and diphenylamine catalyst are added and stirred at room temperature for 8 hours to cause an addition reaction to prepare a liquid crystal elastomer solution.

[0047] S2. Preparation of ionic skin solution: Add polyvinyl pyrrolidone and acetylcholine chloride to the solvent and stir evenly to obtain the ionic skin solution.

[0048] S3. Preparation of breathable ion skin by coaxial electrospinning: Liquid crystal elastomer solution and ion skin solution were taken and a composite fiber membrane was prepared by coaxial electrospinning method. The liquid crystal elastomer solution was used as the core layer and the ion skin solution was used as the sheath layer. The spinning speed ratio of the core and sheath layers was controlled to be 4:3. A voltage of 12kV was applied to spin the fiber membrane. The composite fiber membrane obtained by electrospinning was placed at room temperature and humidity of 50% RH for 24 hours to obtain breathable ion skin. The breathable ion skin has a water content of 6wt%, a resin content of 47wt%, a liquid crystal content of 35wt%, and an ion-conducting active substance content of 12wt%. The composite fiber is characterized as follows: Figure 2 As shown, through TEM-EDS spectrum testing, it can be seen that the S element in the liquid crystal elastomer is distributed in the core layer of the composite fiber, and the Cl element in the ion skin is distributed in the surrounding sheath layer.

[0049] The ion conductivity of the prepared breathable ion skin is 7.2*10 -5 S / m, peeling interface toughness is 347J m -2 , water vapor transmission rate is 1167g m -2 d -1 ,After printing the flexible electrodes, the obtained breathable ion skin sensor can be used to detect blinking movements, such as Figure 3 shown.

[0050] Example 2:

[0051] S1. Preparation of liquid crystal elastomer solution:

[0052] 1,3-phenylenebis(methylene)diacrylate and styrene-ethylene-butylene-styrene block copolymer were added to a solvent and stirred evenly. 1,5-pentanedithiol and diphenylamine catalyst were added and stirred at room temperature for 12 hours to cause an addition reaction to prepare a liquid crystal elastomer solution.

[0053] S2. Preparation of ionic skin solution: Add polyvinyl pyrrolidone and betaine to the solvent and stir evenly to obtain the ionic skin solution.

[0054] S3. Coaxial electrospinning to prepare breathable ion skin: Take the liquid crystal elastomer solution and ion skin solution, and prepare a composite fiber membrane by coaxial electrospinning method. The liquid crystal elastomer solution is used as the core layer and the ion skin solution is used as the sheath layer. The spinning speed ratio of the core and sheath layers is controlled to be 1:2, and the fiber membrane is spun by applying a voltage of 12 kV. The composite fiber membrane prepared by electrospinning is placed at room temperature and humidity of 40% RH for 36 h to obtain a breathable ion skin. In the breathable ion skin, the water content is 8 wt%, the resin content is 37 wt%, the liquid crystal content is 40 wt%, and the ionically active substance content is 15 wt%.

[0055] The ion conductivity of the prepared breathable ion skin is 5.4*10 -4 S / m, the interfacial toughness is 406 J m -2 , and the water vapor transmission rate is 1257 g m -2 d -1 After printing a flexible electrode, the obtained breathable ion skin sensor can be used to detect finger bending, as shown in Figure 3 .

[0056] Example Three:

[0057] S1. Preparation of liquid crystal elastomer solution:

[0058] 1,3-phenylene bis(methylene) divinyl acetate and styrene-ethylene-butylene-styrene block copolymer are added to the solvent, stirred uniformly, 1,5-pentanedithiol and diphenylamine catalyst are added, stirred at room temperature for 12 h, and addition reaction occurs to prepare a liquid crystal elastomer solution.

[0059] S2. Electrospinning to prepare breathable ion skin: Take the liquid crystal elastomer solution, and prepare a fiber membrane by electrospinning method. The voltage is 12 kV. The fiber membrane prepared by electrospinning is placed at room temperature and humidity of 50% RH for 24 h to obtain a breathable ion skin. In the breathable ion skin, the water content is 2 wt%, the resin content is 47 wt%, and the liquid crystal content is 51 wt%.

[0060] The ion conductivity of the prepared breathable ion skin is 8.2*10 -8 S / m, the interfacial toughness is 244 J m -2 , and the water vapor transmission rate is 1365 g m -2 d -1 After printing a flexible electrode, due to the low ion conductivity, the obtained breathable ion skin sensor has a low signal-to-noise ratio when used for body signal detection, and it is not easy to realize detection

[0061] Example Four:

[0062] S1. Preparation of liquid crystal elastomer solution:

[0063] Bisphenol A epoxy diacrylate and polyurethane are added to a solvent and stirred evenly. 2-mercaptoethyl sulfide and diphenylamine catalyst are added and stirred at room temperature for 8 hours to cause an addition reaction to prepare a liquid crystal elastomer solution.

[0064] S2. Preparation of ionic skin solution: Add polyvinyl pyrrolidone and acetylcholine chloride to the solvent and stir evenly to obtain the ionic skin solution.

[0065] S3. Ion Skin Preparation: A liquid crystal elastomer solution was poured into a mold and heated to cure, yielding a liquid crystal elastomer. The liquid crystal elastomer was then immersed in the ion skin solution, removed, and heated to cure. The elastomer was then allowed to stand at room temperature and 50% humidity for 24 hours to yield a composite ion skin. This composite ion skin contained 7% water, 45% resin, 35% liquid crystal, and 13% ion-conducting active material.

[0066] The ion conductivity of the prepared breathable ion skin is 4.9*10 -5 S / m, peeling interface toughness is 386J m -2 , water vapor transmission rate is 692g m -2 d -1 , the moisture permeability is much lower than that of the breathable ionic skin made by coaxial electrospinning.

[0067] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A breathable ionic skin, characterized in that: The following components are included by weight percentage: Water: 5-15wt%; Polymer matrix: 35-55wt%; Liquid crystal elastomer: 25-45wt%; Ion-conducting active material: 10-20 wt%.

2. The breathable ionic skin according to claim 1, characterized in that: The polymer matrix is ​​selected from one or any combination of polyester, polyurethane, styrene-ethylene-butylene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, ethylene propylene rubber, and polyvinyl pyrrolidone.

3. The breathable ionic skin according to claim 1, characterized in that: The liquid crystal elastomer is formed by Michael addition reaction of electron-deficient olefin and nucleophile.

4. The breathable ionic skin according to claim 3, characterized in that: The electron-deficient olefin is selected from one or any combination of bisphenol A epoxy diacrylate, 4,4'-diphenyl diacrylate, 1,3-phenylenebis(methylene) diacrylate, 1,3-phenylenebis(methylene) diacrylate, and 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene.

5. The method for preparing and using breathable ionic skin according to claim 3, characterized in that: The nucleophilic reagent is selected from one or any combination of 2-mercaptoethyl sulfide, 2-aminobenzenethiol, 1,6-hexanedithiol, 1,5-pentanedithiol, butanedithiol, and 2,2'-(1,2-ethanediyldioxy)bis(ethyl mercaptan).

6. The breathable ionic skin according to claim 1, characterized in that: The ion-conducting active substance is selected from one or any combination of acetylcholine chloride, betaine, N,N,N,N-tetramethylethylenediamine, N,N-dimethylglycine, N,N-dimethylaminoethyl acetate, and stachydrine.

7. A method for preparing the breathable ionic skin according to any one of claims 1 to 3 and 6, characterized in that: The following steps are involved: S1. Preparation of liquid crystal elastomer: dissolve the electron-deficient olefin and polymer in a solvent, add a nucleophile and a diphenylamine catalyst, and react at room temperature for 8-16 hours; S2. Preparation of ionic skin solution: dissolving the polymer and the ion-conducting active substance in a solvent and mixing them uniformly; S3, coaxial electrospinning: using the product of step S1 as the core layer and the product of step S2 as the sheath layer, controlling the core-sheath spinning speed ratio to 1:4 to 2:1, applying a voltage of 10-12 kV to spin into a fiber membrane; S4. Curing the obtained fiber membrane at 25-50% RH for 24-48 hours.

8. The method of claim 7, wherein: The solvent is N,N-dimethylformamide, tetrahydrofuran or dimethyl sulfoxide.

9. A breathable ion skin flexible sensor, characterized in that: The ionic skin according to any one of claims 1 to 3 and 6 is formed by printing flexible electrodes on the surface.

10. The breathable ion flexible skin sensor according to claim 9, characterized in that: The flexible electrode is any one of a silver nanowire conductive network and a carbon-based conductive ink.

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