Cellulose-based human body wearable ion hydrogel sensing material as well as preparation method and application thereof
By constructing a cellulose hydrogel with a multiple cross-linked network, the mechanical strength, self-healing and ionic liquid leakage problems of existing materials are solved, and a cellulose-based wearable ionic hydrogel sensing material with high conductivity, excellent mechanical properties and good biocompatibility is achieved, which is suitable for wearable devices on the human body.
Patent Information
- Application Number
- CN202511060325.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-30
- Publication Date
- 2025-09-16
AI Technical Summary
Existing cellulose hydrogel materials are insufficient in mechanical strength, self-healing properties, long-term stability, etc., and ionic liquid doping is prone to leakage, making it difficult to meet the complex scenario requirements of wearable devices on the human body.
Dialdehyde microcrystalline cellulose was prepared by oxidizing microcrystalline cellulose with sodium periodate, and then covalently grafted with histidine ionic liquid through Schiff base reaction. Acrylamide and N,N-methylenebisacrylamide were combined for cross-linking to construct a multiple cross-linked network and form a stable ionized cellulose hydrogel.
The conductivity, mechanical properties, biocompatibility, antibacterial properties and environmental adaptability of the hydrogel are improved, ensuring stable sensing and antibacterial properties during complex movements, and is suitable for wearable devices on the human body.
Smart Images
Figure CN120647841A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of cellulose ion hydrogel composite materials, and in particular relates to a cellulose-based wearable ion hydrogel sensing material for the human body, a preparation method and an application thereof. Background Art
[0002] With the rise of flexible electronics and human health monitoring, wearable materials must combine flexibility, high conductivity, biocompatibility, and environmental stability. Traditional materials (such as silicone and synthetic polymers) suffer from poor biodegradability and inadequate compatibility with human skin. Hydrogels based on natural polymers (such as cellulose and chitosan) have become a research hotspot due to their flexibility, tunable ionic conductivity, and biocompatibility. However, existing hydrogels still require breakthroughs in mechanical strength, self-healing properties, and long-term stability.
[0003] Microcrystalline cellulose is considered an ideal hydrogel matrix due to its high crystallinity, renewability and chemical modifiability. The preparation of cellulose hydrogels by physical crosslinking or chemical crosslinking using existing technologies has the following problems: (1) Single function: Most hydrogels rely solely on the cellulose structure itself and lack active functional groups (such as conductive ions and responsive groups); (2) Toxicity risk: Residual chemical crosslinkers (such as epichlorohydrin) may lead to decreased biocompatibility; (3) Insufficient dynamic performance: Traditional covalent crosslinking networks are difficult to give materials self-healing or environmental response properties, limiting their application in complex wearable scenarios. Ionic liquids are used to enhance the conductivity and functionalization of hydrogels due to their high ionic conductivity, thermal stability and structural designability. In existing technologies, ionic liquids are often introduced into hydrogels by physical doping or simple embedding, but there are problems such as easy leakage and long-term performance degradation. However, there has been no research to organically combine the efficient oxidative modification of cellulose, the covalent grafting of ionic liquids and the design of hydrogel networks.
[0004] In view of the problems of existing hydrogels having single functions, lack of active groups, cross-linker residues caused by chemical cross-linking, insufficient dynamic performance of traditional covalent networks, lack of self-healing / responsiveness, and easy leakage of ionic liquid physical doping leading to performance degradation, it is necessary to find a new cellulose-based wearable ionic hydrogel sensing material and its preparation method and application. By constructing a multiple cross-linked network, it is possible to achieve effective improvement in high conductivity, excellent mechanical properties, biocompatibility, long-term stability, antibacterial properties and interfacial adhesion. Summary of the Invention
[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a cellulose-based wearable ionic hydrogel sensing material for the human body, as well as a preparation method and application, so as to solve the technical problem of how to prepare a cellulose-based wearable ionic hydrogel sensing material for the human body with high conductivity, excellent mechanical properties, good biocompatibility, long-term stability, antibacterial properties and environmental adaptability through covalent grafting of ionic liquids and multiple cross-linked network design.
[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a method for preparing a cellulose-based wearable ionic hydrogel sensing material for the human body, comprising the following steps: Step 1, adding microcrystalline cellulose to deionized water, stirring and ultrasonicating until uniformly dispersed, then adding sodium periodate and stirring to dissolve, adjusting the pH value to 3-4, stirring and reacting in a light-proof environment, adding ethylene glycol to terminate the reaction, vacuum filtering, washing, and vacuum drying to obtain dialdehyde microcrystalline cellulose; Step 2: Dissolve L-histidine and 3-bromopropionic acid in N,N-dimethylformamide and stir to dissolve. After heating for reaction, add ethyl acetate to precipitate a solid, wash the solid, and vacuum dry to obtain a histidine ionic liquid. Step 3, adding the dialdehyde microcrystalline cellulose prepared in step 1 to deionized water and stirring to disperse, then adding the histidine ionic liquid prepared in step 2 and stirring to dissolve, heating and stirring to react, cooling to room temperature, adding anhydrous ethanol to precipitate, vacuum filtering, washing, and vacuum drying to obtain ionized cellulose; Step 4: Dissolve the ionized cellulose prepared in step 3 in deionized water, add acrylamide and stir to dissolve, then add N, N-methylenebisacrylamide, ammonium persulfate and ascorbic acid, and heat with microwave to react to obtain a cellulose-based wearable ionic hydrogel sensing material.
[0007] Preferably, in step 1, the mass ratio of microcrystalline cellulose, deionized water, sodium periodate and ethylene glycol is (5-10): (300-450): (3-6): (100-200) in parts by mass; The diameter of microcrystalline cellulose is 30~50nm, the fiber length of microcrystalline cellulose is 10~20μm, and the average degree of polymerization is 3500.
[0008] Preferably, in step 1, the stirring reaction conditions in a light-proof environment include: stirring at 50-65 ° C for 4-6 h; the washing conditions include: washing three times with an 80% mass fraction of ethanol aqueous solution; and the vacuum drying conditions include: vacuum drying at 50 ° C for 6-7 h.
[0009] Preferably, in step 2, the mass ratio of L-histidine, 3-bromopropionic acid, N, N-dimethylformamide and ethyl acetate is (0.5-1.0): (0.5-1.0): (5-15): (20-50) in parts by mass; The heating reaction conditions include: heating to 80-90° C. under a nitrogen atmosphere for 24-28 hours; the washing conditions include: washing with ethyl acetate three times; and the vacuum drying conditions include: vacuum drying at 30-40° C. for 12-15 hours.
[0010] Preferably, in step 3, the mass ratio of dialdehyde microcrystalline cellulose, deionized water, histidine ionic liquid and anhydrous ethanol is (1-5): (40-200): (0.3-1.5): (100-150) in parts by mass.
[0011] Preferably, in step 3, the conditions for heating and stirring the reaction include: stirring the reaction at 70-80°C for 5-6 hours; the conditions for washing include: washing with anhydrous ethanol three times; and the conditions for vacuum drying include: vacuum drying at 30-50°C for 6-7 hours.
[0012] Preferably, in step 4, the mass ratio of ionized cellulose, deionized water, acrylamide, N, N-methylenebisacrylamide, ammonium persulfate and ascorbic acid is (0.5-2.5): (100-200): (10-30): (0.1-0.2): (0.3-0.4): (0.23-0.32) in parts by mass.
[0013] Preferably, in step 4, the microwave heating reaction conditions include: microwave heating at 40-45° C. for 50-60 min.
[0014] The present invention also discloses a cellulose-based wearable ionic hydrogel sensing material for the human body, which is prepared using the above-mentioned preparation method of the cellulose-based wearable ionic hydrogel sensing material for the human body; the cellulose-based wearable ionic hydrogel for the human body has a tensile strength of 0.23-0.28 MPa, a maximum breaking strain of 514%-752%, a conductivity of 0.139-0.251 mS / cm, a sensing sensitivity of 5.3-6.3, an antibacterial rate against Staphylococcus aureus of 83.4%-96.2%, and an antibacterial rate against Escherichia coli of 85.6%-95.8%.
[0015] The present invention also discloses the use of the cellulose-based human wearable ionic hydrogel sensing material prepared by the preparation method of the above-mentioned cellulose-based human wearable ionic hydrogel sensing material in the preparation of human wearable stress-strain sensing materials or the preparation of flexible electronic sensor electrodes.
[0016] Compared with the prior art, the present invention has the following beneficial effects:The present invention discloses a method for preparing a cellulose-based wearable ionic hydrogel sensing material. Microcrystalline cellulose is selectively oxidized with sodium periodate to convert adjacent hydroxyl groups on the glucose ring into aldehyde groups, producing dialdehyde microcrystalline cellulose. A histidine ionic liquid and the dialdehyde microcrystalline cellulose undergo a Schiff base reaction, covalently grafting the ionic liquid onto the microcrystalline cellulose molecular chain. Polar groups such as carboxyl groups, hydroxyl groups, and amino groups in the resulting product molecules form an interwoven cross-linked network structure through intermolecular forces, hydrogen bonds, ionic bonds, and Schiff base π-π bonds, providing a reliable ionic hydrogel sensing material for wearable electronic devices. The prepared cellulose-based wearable ionic hydrogel sensing material exhibits excellent strength, toughness, water retention, environmental tolerance, interfacial adhesion, and biocompatibility. The prepared hydrogel exhibits multiple interactions, including intermolecular forces, hydrogen bonds, ionic bonds, and covalent bonds, which enhance its strength and flexibility. Its tensile strength ranges from 0.23 to 0.28 MPa, and its strain at break ranges from 514% to 752%. This allows it to adapt to various complex human motions and avoid cracking and deformation. The interwoven, cross-linked network structure enhances the hydrogel's elasticity and durability, ensuring comfort and stability during long-term wear. The various hydrophilic polar groups within the material structure not only increase intermolecular forces but also enhance its water retention and water-locking capacity, effectively inhibiting water evaporation and maintaining a favorable humid environment. The hydrogel can be used within a temperature range of 20°C to 85°C, improving its environmental adaptability, durability, interfacial adhesion, and biocompatibility. The prepared cellulose-based wearable ionic hydrogel sensing material exhibits excellent electrical conductivity. The hydrophilic carboxyl groups in the ionized cellulose network lock free water molecules through hydrogen bonds, forming continuous hydrated ion channels. The imidazolium ions in the dynamic ion network provide mobile charge carriers, enabling ultrafast ion transport. This enhances the high conductivity and sensitivity of the wearable hydrogel sensor material, with conductivity ranging from 0.139 to 0.251 mS / cm and sensitivity ranging from 5.3 to 6.3. The cellulose-based wearable ionic hydrogel sensor material exhibits excellent antibacterial properties. The carboxyl and hydroxyl groups in the prepared cellulose-based hydrogel sensor material enable mild adhesion to skin tissue. Furthermore, the positively charged imidazolium groups in the amino acid ionic liquid within the hydrogel sensor material effectively inhibit the growth of various pathogens, with inhibition rates of 83.4% to 96.2% against Staphylococcus aureus and 85.6% to 95.8% against Escherichia coli. This enhances the safety and durability of the hydrogel sensor material. The synergistic adhesion and antibacterial properties provide a more reliable and hygienic functional guarantee for its use in wearable devices. Cellulose-based wearable ionic hydrogel sensing materials are environmentally friendly, low-cost, and have good practicality.The use of microcrystalline cellulose derived from natural cellulose as the base raw material is in line with the concept of green and sustainable development. The preparation process is simple and does not contain highly toxic or harmful solvents, which reduces environmental pollution and energy consumption, and is conducive to industrial promotion. The selection of raw materials and modifiers takes cost factors into consideration to ensure that the material preparation process is economical and practical, and improve market competitiveness. Cellulose-based wearable ionic hydrogel sensing materials have a wide range of uses, strong practicality, and good application prospects. Due to their excellent strength, flexibility, conductivity, high sensitivity, biocompatibility, and antibacterial properties, they are suitable as sensing materials for various intelligent wearable devices such as biosensors, flexible electrodes, and smart medical patches. They can respond to mechanical stimuli in real time and are used in intelligent robots, human health monitoring, and other fields.
[0017] Furthermore, the mass ratio of microcrystalline cellulose, deionized water, sodium periodate, and ethylene glycol is (5-10): (300-450): (3-6): (100-200); ensuring the selective oxidation efficiency of microcrystalline cellulose by sodium periodate to avoid excessive residual oxidant or insufficient oxidation; microcrystalline cellulose with specific parameters provides a suitable skeleton for subsequent grafting reaction and network construction, ensures the structural stability of dialdehyde microcrystalline cellulose, and lays the foundation for the mechanical properties and functional foundation of the hydrogel.
[0018] Furthermore, a light-proof reaction environment with a pH of 3-4 ensures the selective oxidation of hydroxyl groups by sodium periodate, reducing side reactions; ethanol washing effectively removes residual reagents and avoids toxicity risks; and vacuum drying prevents aldehyde oxidation, ensuring the reactivity of dialdehyde microcrystalline cellulose and providing sufficient aldehyde sites for subsequent ionic liquid grafting.
[0019] Furthermore, the mass ratio of L-histidine, 3-bromopropionic acid, N, N-dimethylformamide and ethyl acetate is (0.5~1.0): (0.5~1.0): (5~15): (20~50); a nitrogen atmosphere prevents oxidation of the raw materials, and precise ratios and reaction temperatures ensure that histidine and 3-bromopropionic acid fully react to form a stable histidine ionic liquid; ethyl acetate washing removes unreacted monomers, improves the purity of the ionic liquid, and prevents impurities from affecting subsequent grafting reactions and hydrogel biocompatibility.
[0020] Furthermore, the mass ratio of dialdehyde microcrystalline cellulose, deionized water, histidine ionic liquid and anhydrous ethanol is (1~5): (40~200): (0.3~1.5): (100~150); ensuring that the histidine ionic liquid reacts fully with the Schiff base of dialdehyde microcrystalline cellulose, avoiding ungrafted residues caused by excessive ionic liquid and preventing insufficient dosage from affecting the conductivity of the hydrogel, solving the problem of easy leakage of physical doping of ionic liquid through covalent grafting, and ensuring the long-term stability of the material.
[0021] Furthermore, the conditions for the heating and stirring reaction include: stirring the reaction at 70-80°C for 5-6 hours; promoting the complete Schiff base reaction to stably graft the ionic liquid onto the cellulose chain; washing with anhydrous ethanol to remove free ionic liquid to avoid subsequent ion leakage in the hydrogel, and vacuum drying to retain the polar groups of the grafted product, providing a basis for constructing a multiple cross-linked network.
[0022] Furthermore, the mass ratio of ionized cellulose, deionized water, acrylamide, N, N-methylenebisacrylamide, ammonium persulfate and ascorbic acid is (0.5~2.5): (100~200): (10~30): (0.1~0.2): (0.3~0.4): (0.23~0.32); ensuring that the hydrogel forms a uniform interwoven cross-linked network; avoiding excessive cross-linking agent leading to material embrittlement, and preventing insufficient dosage from affecting mechanical properties, ultimately improving the strength, toughness and elasticity of the hydrogel.
[0023] Furthermore, the conditions for the microwave heating reaction include: microwave heating to 40~45℃ for 50~60 minutes; microwave heating is uniform and efficient, and low-temperature reaction avoids the destruction of active groups in ionized cellulose while ensuring sufficient polymerization of acrylamide; controlling the reaction time can prevent excessive cross-linking of the network, giving the hydrogel good flexibility and water retention to meet the needs of human wear.
[0024] The present invention also discloses a wearable cellulose-based ionic hydrogel sensing material prepared by the above-mentioned preparation method. The wearable cellulose-based ionic hydrogel has a tensile strength of 0.23-0.28 MPa and a maximum breaking strain of 514%-752%. It can withstand complex movements such as bending and stretching, avoid cracking or excessive deformation, and ensure structural stability during wear. Its conductivity is 0.139-0.251 mS / cm, and its sensing sensitivity is 5.3-6.3. It can efficiently conduct ionic signals and accurately respond to mechanical stimulation, providing reliable signal output for stress-strain monitoring. Its antibacterial rate against Staphylococcus aureus is 83.4%-96.2%, and its antibacterial rate against Escherichia coli is 85.6%-95.8%. It can inhibit bacterial growth in skin contact areas. Furthermore, the material has no toxic crosslinker residues and good biocompatibility, reducing the risk of skin irritation from long-term wear. This invention uses microcrystalline cellulose as a raw material, directly attaching an ionic liquid to a cellulose backbone via chemical bonds to prepare an ionized cellulose liquid. This process then creates a hydrogel material with excellent ionic conductivity, mechanical properties, antimicrobial properties, water retention, structural stability, and biocompatibility. This approach addresses the diverse needs of wearable devices and represents an important development in this field. The resulting hydrogel exhibits excellent strength, flexibility, antimicrobial properties, water retention, biocompatibility, high conductivity, high sensitivity, and strong environmental adaptability, and can be used as a wearable stress-strain sensing material or as an electrode in flexible electronic sensors.
[0025] The present invention also discloses the use of the cellulose-based wearable ionic hydrogel sensing material prepared by the above-mentioned preparation method in the preparation of wearable stress-strain sensing materials for the human body or the preparation of flexible electronic sensor electrodes. The high sensitivity of 5.3~6.3 can capture the stress-strain signals of small and large movements of the human body in real time. The maximum breaking strain of 514%~752% ensures continuous and stable sensing during exercise and avoids signal interruption. The high ionic conductivity of 0.139~0.251mS / cm ensures the conductive efficiency of the electrode and reduces signal loss. The biocompatibility and antibacterial properties reduce the risk of allergies or infection caused by skin contact with the electrode, improving the safety of long-term wear. The interfacial adhesion enables it to fit tightly to the skin, avoiding poor electrode contact due to displacement. It can be used in different temperature environments and is adaptable to various wearing scenarios. The environmentally friendly and low-cost preparation materials provide economic and ecological feasibility for large-scale application. The present invention prepares a cellulose-based wearable ionic hydrogel sensing material for the human body through chemical modification and ionic cross-linking, which has good ionic conductivity, sensitivity, mechanical properties, antibacterial properties, water retention, structural stability, strong environmental adaptability and biocompatibility. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 Schematic diagram of the interwoven cross-linked network structure in cellulose-based wearable ionic hydrogel sensing materials; Figure 2 Schematic diagram of the preparation process of cellulose-based wearable ionic hydrogel sensing materials; (a) shows the chemical reaction in which sodium periodate is used to selectively oxidize adjacent hydroxyl groups on the glucose ring in microcrystalline cellulose to form aldehyde groups; (b) shows the chemical reaction in which L-histidine and 3-bromopropionic acid react to prepare histidine ionic liquid; (c) shows the Schiff base reaction of histidine ionic liquid with dialdehyde microcrystalline cellulose; and (d) shows the cross-linking polymerization reaction of polyacrylamide and N, N-methylenebisacrylamide in an ionic liquid-modified microcrystalline cellulose solution. Figure 3 Scanning electron micrographs of the cellulose-based wearable ionic hydrogel sensing material prepared in Example 1 and the hydrogel prepared in Control Example 1; (a) is the hydrogel prepared in Control Example 1; (b) is the cellulose-based wearable ionic hydrogel sensing material prepared in Example 1; Figure 4 These are actual photos of the cellulose-based wearable ionic hydrogel sensing material prepared in Example 1 in its original state and stretched state. DETAILED DESCRIPTION
[0027] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0028] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.
[0029] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.
[0030] In the present invention, unless otherwise specified, percentages (%) or parts refer to percentages by weight or parts by weight relative to the composition.
[0031] In the present invention, unless otherwise specified, the components involved or their preferred components can be combined with each other to form a new technical solution.
[0032] In this disclosure, unless otherwise specified, the numerical range "a-b" is an abbreviation for any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "6-22" indicates that all real numbers between "6-22" are listed herein, and "6-22" is merely an abbreviation for these numerical combinations.
[0033] The "range" disclosed in the present invention is in the form of a lower limit and an upper limit, which can be one or more lower limits, and one or more upper limits, respectively.
[0034] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.
[0035] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the order. Preferably, the reaction method herein is carried out sequentially.
[0036] Unless otherwise indicated, the professional and scientific terms used herein are the same as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.
[0037] The present invention provides a method for preparing a cellulose-based wearable ionic hydrogel sensing material, comprising the following steps: Step 1, by mass, add 5 to 10 parts of microcrystalline cellulose to 300 to 450 parts of deionized water, stir and ultrasonicate until the microcrystalline cellulose is uniformly dispersed, then add 3 to 6 parts of sodium periodate and stir to dissolve, adjust the pH value of the solution to 3 to 4, stir at 50 to 65 ° C in a dark environment for 4 to 6 hours, add 80 to 200 parts of ethylene glycol to terminate the reaction, vacuum filter to obtain a white solid, wash with 200 to 300 parts of an aqueous solution with an ethanol content of 80% three times, and then vacuum dry at 50 ° C for 6 to 7 hours to obtain dialdehyde microcrystalline cellulose; Step 2, by weight, dissolving 0.5-1.0 parts of L-histidine and 0.5-1.0 parts of 3-bromopropionic acid in 5-15 parts of N,N-dimethylformamide, stirring and dissolving, heating to 80-90°C under a nitrogen atmosphere for 24-28 hours, adding 20-50 parts of ethyl acetate to precipitate a solid, washing the solid with 100-150 parts of ethyl acetate three times, and vacuum drying at 30-40°C for 12-15 hours to obtain a histidine ionic liquid; Step 3, by mass, 1 to 5 parts of dialdehyde microcrystalline cellulose are added to 40 to 200 parts of deionized water and stirred to disperse, and then 0.3 to 1.5 parts of histidine ionic liquid are added and stirred to dissolve to obtain a yellow mixed solution, and the mixture is stirred and reacted at 70 to 80 ° C for 5 to 6 hours, cooled to room temperature, and 100 to 150 parts of anhydrous ethanol are added to precipitate, vacuum filtered, and the precipitate is washed with 150 to 200 parts of anhydrous ethanol three times, and then vacuum dried at 30 to 50 ° C for 6 to 7 hours to obtain ionized cellulose.
[0038] Step 4: Dissolve 0.5-2.5 parts of ionized cellulose in 100-200 parts of deionized water, add 10-30 parts of acrylamide and stir to dissolve, then add 0.1-0.2 parts of N, N-methylenebisacrylamide, 0.3-0.4 parts of ammonium persulfate and 0.23-0.32 parts of ascorbic acid, and microwave heat to 40-45°C for 50-60 min to obtain a cellulose-based wearable ionic hydrogel sensing material.
[0039] The diameter of the microcrystalline cellulose in Examples 1-5 was 30-50 nm, the fiber length was 10-20 μm, and the average degree of polymerization was 3500.
[0040] All chemical reagents in Examples 1 to 5 were of analytical grade with a purity of 99%.
[0041] The present invention obtains dialdehyde microcrystalline cellulose by oxidizing microcrystalline cellulose with sodium periodate, and uses the Schiff base reaction of histidine ionic liquid and dialdehyde microcrystalline cellulose to achieve ionic liquid covalent grafting, and finally constructs an interwoven cross-linked network. This method organically combines cellulose oxidation modification, ionic liquid covalent grafting and hydrogel network design, solving the problems of traditional hydrogels with single functions and easy leakage of ionic liquids. It provides a unique technical route for the preparation of ionic hydrogels with reliable performance and is significantly innovative. The prepared hydrogel has good strength, flexibility, antibacterial properties, water retention, structural stability, biocompatibility, high conductivity, high sensitivity and strong environmental adaptability, and can be used as a wearable stress-strain sensing material for the human body or an electrode in a flexible electronic sensor sensing material. Through multiple forces, including hydrogen, ionic, and covalent bonds, the material forms a stable network, exhibiting excellent mechanical properties. Its tensile strength ranges from 0.23 to 0.28 MPa, its strain at break from 514% to 752%, and its electrical conductivity from 0.139 to 0.251 mS / cm, demonstrating excellent conductivity and biocompatibility, meeting the core material performance requirements for wearable devices. The material's sensing sensitivity ranges from 5.5 to 6.3, adapting to complex movements. Its antibacterial rate against Staphylococcus aureus ranges from 83.4% to 96.2%, along with its excellent antibacterial and biocompatibility, enables it to precisely respond to the stress-strain changes associated with human motion and is suitable for skin contact scenarios, providing a reliable sensing material for applications in flexible electronics, health monitoring, and other fields.
[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0043] Example 1 A method for preparing a cellulose-based wearable ionic hydrogel sensing material for the human body comprises the following steps: Step 1, by mass, 5 parts of microcrystalline cellulose were added to 300 parts of deionized water, stirred and ultrasonicated until the microcrystalline cellulose was evenly dispersed, and then 3 parts of sodium periodate were added and stirred to dissolve, the pH value of the solution was adjusted to 3, and stirred at 50 ° C for 4 hours in a dark environment. 80 parts of ethylene glycol were added to terminate the reaction, and a white solid was obtained by vacuum filtration. The solid was washed with 200 parts of an 80% ethanol aqueous solution three times, and then vacuum dried at 50 ° C for 6 hours to obtain dialdehyde microcrystalline cellulose; Step 2: Dissolve 0.5 parts of L-histidine and 0.5 parts of 3-bromopropionic acid in 5 parts of N, N-dimethylformamide, stir and dissolve, heat to 80°C under a nitrogen atmosphere for 24 hours, add 20 parts of ethyl acetate to precipitate a solid, wash the solid with 100 parts of ethyl acetate three times, and vacuum dry at 30°C for 12 hours to obtain a histidine ionic liquid; Step 3: Add 1 part of dialdehyde microcrystalline cellulose to 40 parts of deionized water and stir to disperse, then add 0.3 parts of histidine ionic liquid and stir to dissolve to obtain a yellow mixed solution, stir and react at 70 ° C for 5 hours, cool to room temperature, add 100 parts of anhydrous ethanol to precipitate, vacuum filter, wash the precipitate with 150 parts of anhydrous ethanol three times, and then vacuum dry at 30 ° C for 6 hours to obtain ionized cellulose.
[0044] Step 4: Dissolve 0.5 parts of ionized cellulose in 100 parts of deionized water, add 10 parts of acrylamide and stir to dissolve, then add 0.1 parts of N, N-methylenebisacrylamide, 0.3 parts of ammonium persulfate and 0.23 parts of ascorbic acid, and microwave heat to 40°C for 50 minutes to obtain a cellulose-based wearable ionic hydrogel sensing material.
[0045] Figure 1 A schematic diagram of the interwoven, cross-linked network structure in a cellulose-based wearable ionic hydrogel sensing material. The figure shows that the prepared hydrogel is composed of a cross-linked polymer of microcrystalline cellulose grafted with histidine ionic liquid, polyacrylamide, and N,N-methylenebisacrylamide. Its structure is an interwoven, cross-linked structure. Molecular chains containing imidazolium cations, hydroxyl groups, carboxyl groups, and oxygen-ether bonds interact with each other through intermolecular forces, hydrogen bonds, and ionic bonds, forming an interwoven, cross-linked network. This provides the foundation for the hydrogel's strength, toughness, adhesion, biocompatibility, conductivity, sensitivity, and antibacterial properties.
[0046] Figure 2Schematic diagram of the preparation process of a cellulose-based wearable ionic hydrogel sensing material. (a) The chemical reaction in which sodium periodate is used to selectively oxidize adjacent hydroxyl groups on the glucose rings of microcrystalline cellulose to form aldehyde groups, converting the hydroxyl groups of the microcrystalline cellulose into more active aldehyde groups and preparing the structural basis for the modification of the microcrystalline cellulose. (b) The chemical reaction in which L-histidine and 3-bromopropionic acid are reacted to prepare a histidine ionic liquid. Its structure contains imidazolium cations, which can impart antimicrobial properties, conductivity, and enhance intermolecular interactions to the hydrogel. (c) The Schiff base reaction in which the histidine ionic liquid is reacted with dialdehyde microcrystalline cellulose to covalently graft the ionic liquid onto the microcrystalline cellulose molecular chain, resulting in an ionic liquid-modified microcrystalline cellulose. Its structure contains carboxyl groups, hydroxyl groups, imidazolium cations, bromide anions, residual aldehyde groups, and oxygen ether bonds, providing the material and structural basis for forming an interwoven cross-linked structure and imparting antimicrobial properties. (d) Shows the cross-linking polymerization reaction of polyacrylamide and N, N-methylenebisacrylamide in the ionic liquid modified microcrystalline cellulose solution. The molecules in the hydrogel contain carboxyl groups, hydroxyl groups, amino groups, imidazole cations, bromide anions, residual aldehyde groups, oxygen ether bonds, etc. They can form an interwoven cross-linked network structure through intermolecular forces, hydrogen bonds, ionic bonds, Schiff base reactions, etc., providing reliable ionic hydrogel sensing materials for wearable electronic devices on the human body.
[0047] Figure 3 Scanning electron micrographs of the cellulose-based wearable ionic hydrogel sensing material prepared in Example 1 and the hydrogel prepared in Control Example 1. (a) shows the hydrogel prepared in Control Example 1; (b) shows the cellulose-based wearable ionic hydrogel sensing material prepared in Example 1. As can be seen from the figure, the cellulose-based wearable ionic hydrogel sensing material prepared in Example 1 has smaller pores, densely packed pores, and an interwoven, cross-linked structure. The microstructure of the hydrogel in Control Example 1 shows relatively large pores and lacks the basic hydrogel structure.
[0048] Figure 4 These are actual photos of the cellulose-based wearable ionic hydrogel sensing material for the human body prepared in Example 1 in its original state and stretched state. It can be seen that the hydrogel in Example 1 has good tensile toughness, indicating that it can be used as a wearable hydrogel sensing material for the human body.
[0049] Example 2 A method for preparing a cellulose-based wearable ionic hydrogel sensing material for the human body comprises the following steps: Step 1, by mass, 7 parts of microcrystalline cellulose were added to 330 parts of deionized water, stirred and ultrasonicated until the microcrystalline cellulose was uniformly dispersed, and then 4 parts of sodium periodate were added and stirred to dissolve, and the pH value of the solution was adjusted to 3.5. The mixture was stirred at 55 ° C for 4.5 h in a dark environment, and 130 parts of ethylene glycol were added to terminate the reaction. The white solid was vacuum filtered to obtain the white solid, which was washed with 230 parts of an 80% ethanol aqueous solution three times, and then vacuum dried at 50 ° C for 7 h to obtain dialdehyde microcrystalline cellulose; Step 2: Dissolve 0.7 parts of L-histidine and 0.7 parts of 3-bromopropionic acid in 10 parts of N, N-dimethylformamide, stir and dissolve, heat to 85°C under a nitrogen atmosphere for 26 hours, add 40 parts of ethyl acetate to precipitate a solid, wash the solid with 120 parts of ethyl acetate three times, and vacuum dry at 40°C for 14 hours to obtain a histidine ionic liquid; Step 3: Add 2 parts of dialdehyde microcrystalline cellulose to 80 parts of deionized water and stir to disperse them, then add 0.7 parts of histidine ionic liquid and stir to dissolve to obtain a yellow mixed solution, stir and react at 80°C for 6 hours, cool to room temperature, add 130 parts of anhydrous ethanol to precipitate, vacuum filter, wash the precipitate with 180 parts of anhydrous ethanol three times, microwave heat to 43°C and vacuum dry for 7 hours to obtain ionized cellulose.
[0050] Step 4: Dissolve 1.0 part of ionized cellulose in 150 parts of deionized water, add 20 parts of acrylamide and stir to dissolve, then add 0.15 parts of N, N-methylenebisacrylamide, 0.33 parts of ammonium persulfate and 0.25 parts of ascorbic acid, and microwave heat to 45°C for 53 minutes to obtain a cellulose-based wearable ionic hydrogel sensing material.
[0051] Example 3 A method for preparing a cellulose-based wearable ionic hydrogel sensing material for the human body comprises the following steps: Step 1, by mass, 8 parts of microcrystalline cellulose were added to 380 parts of deionized water, stirred and ultrasonicated until the microcrystalline cellulose was uniformly dispersed, and then 4.5 parts of sodium periodate were added and stirred to dissolve, and the pH value of the solution was adjusted to 3.5. The mixture was stirred at 60 ° C for 5 h in a dark environment, and 120 parts of ethylene glycol were added to terminate the reaction. The white solid was vacuum filtered to obtain the white solid, which was washed with 260 parts of an 80% ethanol aqueous solution three times, and then vacuum dried at 50 ° C for 6 h to obtain dialdehyde microcrystalline cellulose; Step 2: Dissolve 0.8 parts of L-histidine and 0.7 parts of 3-bromopropionic acid in 11 parts of N, N-dimethylformamide, stir and dissolve, heat to 90°C under a nitrogen atmosphere for 27 hours, add 40 parts of ethyl acetate to precipitate a solid, wash the solid with 130 parts of ethyl acetate three times, and vacuum dry at 40°C for 15 hours to obtain a histidine ionic liquid; Step 3: Add 3 parts of dialdehyde microcrystalline cellulose to 120 parts of deionized water and stir to disperse, then add 1.0 part of histidine ionic liquid and stir to dissolve to obtain a yellow mixed solution, stir and react at 80°C for 6 hours, cool to room temperature, add 140 parts of anhydrous ethanol to precipitate, vacuum filter, wash the precipitate with 200 parts of anhydrous ethanol three times, and then vacuum dry at 50°C for 6 hours to obtain ionized cellulose.
[0052] Step 4: Dissolve 1.8 parts of ionized cellulose in 180 parts of deionized water, add 25 parts of acrylamide and stir to dissolve, then add 0.2 parts of N, N-methylenebisacrylamide, 0.36 parts of ammonium persulfate and 0.28 parts of ascorbic acid, and microwave heat to 45°C for 56 minutes to obtain a cellulose-based wearable ionic hydrogel sensing material.
[0053] Example 4 A method for preparing a cellulose-based wearable ionic hydrogel sensing material for the human body comprises the following steps: Step 1, by mass, 9 parts of microcrystalline cellulose were added to 420 parts of deionized water, stirred and ultrasonicated until the microcrystalline cellulose was uniformly dispersed, 5 parts of sodium periodate were added and stirred to dissolve, the pH value of the solution was adjusted to 3, stirred at 50 ° C for 4 hours in a dark environment, 200 parts of ethylene glycol were added to terminate the reaction, and vacuum filtration was performed to obtain a white solid, which was washed three times with 300 parts of an aqueous solution with an ethanol content of 80%, and then vacuum dried at 50 ° C for 6 hours to obtain dialdehyde microcrystalline cellulose; Step 2: Dissolve 0.85 parts of L-histidine and 0.80 parts of 3-bromopropionic acid in 13 parts of N, N-dimethylformamide, stir and dissolve, heat to 85°C under a nitrogen atmosphere for 26 hours, add 50 parts of ethyl acetate to precipitate a solid, wash the solid with 140 parts of ethyl acetate three times, and vacuum dry at 40°C for 15 hours to obtain a histidine ionic liquid; Step 3: Add 4 parts of dialdehyde microcrystalline cellulose to 180 parts of deionized water and stir to disperse, then add 1.3 parts of histidine ionic liquid and stir to dissolve to obtain a yellow mixed solution, stir and react at 70°C for 6 hours, cool to room temperature, add 150 parts of anhydrous ethanol to precipitate, vacuum filter, wash the precipitate with 200 parts of anhydrous ethanol three times, and then vacuum dry at 30°C for 7 hours to obtain ionized cellulose.
[0054] Step 4: Dissolve 2.0 parts of ionized cellulose in 200 parts of deionized water, add 26 parts of acrylamide and stir to dissolve, then add 0.18 parts of N, N-methylenebisacrylamide, 0.38 parts of ammonium persulfate and 0.30 parts of ascorbic acid, and microwave heat to 40°C for 58 minutes to obtain a cellulose-based wearable ionic hydrogel sensing material.
[0055] Example 5 A method for preparing a cellulose-based wearable ionic hydrogel sensing material for the human body comprises the following steps: Step 1, by mass, 10 parts of microcrystalline cellulose were added to 450 parts of deionized water, stirred and ultrasonicated until the microcrystalline cellulose was uniformly dispersed, 6 parts of sodium periodate were added and stirred to dissolve, the pH value of the solution was adjusted to 4, and stirred at 65 ° C for 6 hours in a dark environment. 200 parts of ethylene glycol were added to terminate the reaction, and a white solid was obtained by vacuum filtration. The solid was washed with 300 parts of an 80% ethanol aqueous solution three times, and then vacuum dried at 50 ° C for 6 hours to obtain dialdehyde microcrystalline cellulose; Step 2: Dissolve 1.0 parts of L-histidine and 1.0 parts of 3-bromopropionic acid in 15 parts of N, N-dimethylformamide, stir and dissolve, heat to 90°C under a nitrogen atmosphere for 28 hours, add 50 parts of ethyl acetate to precipitate a solid, wash the solid with 150 parts of ethyl acetate three times, and vacuum dry at 40°C for 15 hours to obtain a histidine ionic liquid; Step 3: Add 5 parts of dialdehyde microcrystalline cellulose to 200 parts of deionized water and stir to disperse them, then add 1.5 parts of histidine ionic liquid and stir to dissolve to obtain a yellow mixed solution, stir and react at 80°C for 6 hours, cool to room temperature, add 150 parts of anhydrous ethanol to precipitate, vacuum filter, wash the precipitate with 200 parts of anhydrous ethanol three times, and then vacuum dry at 50°C for 7 hours to obtain ionized cellulose.
[0056] Step 4: Dissolve 2.5 parts of ionized cellulose in 200 parts of deionized water, add 30 parts of acrylamide and stir to dissolve, then add 0.2 parts of N, N-methylenebisacrylamide, 0.4 parts of ammonium persulfate and 0.32 parts of ascorbic acid, and microwave heat to 45°C for 60 minutes to obtain a cellulose-based wearable ionic hydrogel sensing material.
[0057] Control Example Control Example 1 and Control Example 2 are non-modified microcrystalline cellulose hydrogels prepared according to step 4 of the methods of Example 3 and Example 5, respectively.
[0058] The performance of the cellulose-based wearable ion hydrogel sensing materials prepared in Examples 1 to 5 was tested, and the performance parameters of Control Example 1 and Control Example 2 were also tested. The results are shown in Table 1.
[0059] Table 1 Performance parameters of cellulose-based wearable ionic hydrogel sensing materials
[0060] Table 1 shows the performance parameters of the cellulose-based wearable ionic hydrogel sensing material. As can be seen from Table 1, the cellulose-based wearable ionic hydrogels prepared in Examples 1 to 5 have a tensile strength of 0.23 to 0.28 MPa, a maximum fracture strain of 514% to 752%, a conductivity of 0.139 to 0.251 mS / cm, a sensing sensitivity of 5.3 to 6.3, an antibacterial rate against Staphylococcus aureus (S. aureus) of 83.4% to 96.2%, and an antibacterial rate against Escherichia coli (E. coli) of 85.6% to 95.8%. In comparison, the tensile strengths of Control Examples 1 and 2, which do not contain histidine ionic liquid modified microcrystalline cellulose, were 0.14 MPa and 0.15 MPa, respectively, the breaking strains were 322% and 357%, respectively, the electrical conductivities were 0.0152 mS / cm and 0.0156 mS / cm, respectively, the sensitivities were 1.6 and 1.8, respectively, the inhibition rates against Staphylococcus aureus were 3.81% and 3.86%, respectively, and the inhibition rates against Escherichia coli were 4.79% and 4.86%, respectively. The performance parameters of the examples were significantly higher than those of the control group. This is because the hydrogels prepared in Examples 1 to 5 are composed of a cross-linked polymer formed by a Schiff base reaction between histidine ionic liquid and dialdehyde cellulose to form a graft product containing imidazolium cations, polyacrylamide, and N,N-methylenebisacrylamide. The cross-linked polymer has an interwoven cross-linked structure. The molecular chains contain imidazolium cations, hydroxyl groups, carboxyl groups, and oxygen ether bonds, which can form intermolecular forces, hydrogen bonds, and ionic bonds with each other, resulting in an interwoven cross-linked network structure between the modified microcrystalline cellulose molecular chains and between the modified microcrystalline cellulose molecular chains and the polyacrylamide molecular chains, synergistically improving the mechanical properties, conductivity, high sensitivity, biocompatibility, and antibacterial properties of the hydrogel.
[0061] In summary, the present invention discloses a method for preparing and applying a wearable cellulose-based ionic hydrogel sensor material. The method comprises: oxidizing microcrystalline cellulose in deionized water with sodium periodate to obtain dialdehyde microcrystalline cellulose; dissolving L-histidine and 3-bromopropionic acid in N,N-dimethylformamide to prepare a histidine ionic liquid; adding the dialdehyde microcrystalline cellulose to deionized water and the histidine ionic liquid, and drying to obtain ionized cellulose; and dissolving the ionized cellulose in deionized water, adding acrylamide, N,N-methylenebisacrylamide, and ammonium persulfate to react to obtain the wearable cellulose-based ionic hydrogel sensor material. The wearable cellulose-based ionic hydrogel material, prepared by chemical modification and ionic crosslinking, exhibits excellent strength, flexibility, antibacterial properties, water retention, biocompatibility, high conductivity, high sensitivity, and environmental adaptability.
[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a cellulose-based wearable ionic hydrogel sensing material, characterized in that: The steps include: Step 1, adding microcrystalline cellulose to deionized water, stirring and ultrasonicating until uniformly dispersed, then adding sodium periodate and stirring to dissolve, adjusting the pH value to 3-4, stirring and reacting in a light-proof environment, adding ethylene glycol to terminate the reaction, vacuum filtering, washing, and vacuum drying to obtain dialdehyde microcrystalline cellulose; Step 2: Dissolve L-histidine and 3-bromopropionic acid in N,N-dimethylformamide and stir to dissolve. After heating for reaction, add ethyl acetate to precipitate a solid, wash the solid, and vacuum dry to obtain a histidine ionic liquid. Step 3, adding the dialdehyde microcrystalline cellulose prepared in step 1 to deionized water and stirring to disperse, then adding the histidine ionic liquid prepared in step 2 and stirring to dissolve, heating and stirring to react, cooling to room temperature, adding anhydrous ethanol to precipitate, vacuum filtering, washing, and vacuum drying to obtain ionized cellulose; Step 4: Dissolve the ionized cellulose prepared in step 3 in deionized water, add acrylamide and stir to dissolve, then add N, N-methylenebisacrylamide, ammonium persulfate and ascorbic acid, and heat with microwave to react to obtain a cellulose-based wearable ionic hydrogel sensing material.
2. The method for preparing a cellulose-based wearable ionic hydrogel sensing material according to claim 1, characterized in that: In step 1, the mass ratio of the microcrystalline cellulose, deionized water, sodium periodate and ethylene glycol is (5-10): (300-450): (3-6): (100-200) in parts by mass; The diameter of the microcrystalline cellulose is 30-50 nm, the fiber length of the microcrystalline cellulose is 10-20 μm, and the average degree of polymerization is 3500.
3. The method for preparing a cellulose-based wearable ionic hydrogel sensing material according to claim 1, characterized in that: In step 1, the stirring reaction conditions in a light-proof environment include: stirring at 50-65 ° C for 4-6 h; the washing conditions include: washing three times with 80% ethanol aqueous solution by mass; the vacuum drying conditions include: vacuum drying at 50 ° C for 6-7 h.
4. The method for preparing a cellulose-based wearable ionic hydrogel sensing material according to claim 1, wherein: In step 2, the mass ratio of L-histidine, 3-bromopropionic acid, N, N-dimethylformamide and ethyl acetate is (0.5-1.0): (0.5-1.0): (5-15): (20-50) in parts by mass; The heating reaction conditions include: heating to 80-90° C. under a nitrogen atmosphere for 24-28 hours; the washing conditions include: washing with ethyl acetate three times; and the vacuum drying conditions include: vacuum drying at 30-40° C. for 12-15 hours.
5. The method for preparing a cellulose-based wearable ionic hydrogel sensing material according to claim 1, characterized in that: In step 3, the mass ratio of the dialdehyde microcrystalline cellulose, deionized water, histidine ionic liquid and anhydrous ethanol is (1-5): (40-200): (0.3-1.5): (100-150) in parts by mass.
6. The method for preparing a cellulose-based wearable ionic hydrogel sensing material according to claim 1, characterized in that: In step 3, the heating and stirring reaction conditions include: stirring the reaction at 70-80 ° C for 5-6 hours; the washing conditions include: washing with anhydrous ethanol three times; the vacuum drying conditions include: vacuum drying at 30-50 ° C for 6-7 hours.
7. The method for preparing a cellulose-based wearable ionic hydrogel sensing material according to claim 1, characterized in that: In step 4, the mass ratio of the ionized cellulose, deionized water, acrylamide, N, N-methylenebisacrylamide, ammonium persulfate and ascorbic acid is (0.5-2.5): (100-200): (10-30): (0.1-0.2): (0.3-0.4): (0.23-0.32) in parts by mass.
8. The method for preparing a cellulose-based wearable ionic hydrogel sensing material according to claim 1, characterized in that: In step 4, the microwave heating reaction conditions include: microwave heating at 40-45° C. for 50-60 min.
9. A cellulose-based wearable ionic hydrogel sensing material for the human body, characterized in that: The cellulose-based wearable ionic hydrogel sensing material is prepared by the preparation method of any one of claims 1 to 8; the cellulose-based wearable ionic hydrogel has a tensile strength of 0.23-0.28 MPa, a maximum breaking strain of 514%-752%, a conductivity of 0.139-0.251 mS / cm, a sensing sensitivity of 5.3-6.3, an antibacterial rate against Staphylococcus aureus of 83.4%-96.2%, and an antibacterial rate against Escherichia coli of 85.6%-95.8%.
10. Use of the cellulose-based wearable human ionic hydrogel sensing material prepared by the preparation method of the cellulose-based wearable human ionic hydrogel sensing material according to any one of claims 1 to 8 in the preparation of a wearable human stress-strain sensing material or a flexible electronic sensor electrode.