Preparation method and application of high-toughness high-conductivity silk micro-nano fibril restructured eutectic gel

Abstract

The application relates to the technical field of low eutectic gel materials, and discloses a preparation method and application of a high-strength high-toughness high-conductivity silk micro-nano fibril restructured low eutectic gel. The preparation method comprises the following steps: based on the hydrogen bond network and the solvent effect of a choline chloride / acrylic acid type polymerizable low eutectic solvent (PDES), heat-stimulated silk fibers are in-situ depolymerized to form silk micro-nano fibrils (SMNF) which are strongly compatible with the system and serve as reinforced units of the restructured gel network; further, liquid metal droplets are used to directly induce in-situ polymerization of acrylic acid monomers in the SMNF-PDES mixed system at room temperature to prepare the SMNF restructured low eutectic gel, so that the mechanical properties and ionic conductivity of the low eutectic gel are synergistically improved, the inherent contradiction that the mechanical properties and ionic conductivity of the low eutectic gel are difficult to balance is solved, and the low eutectic gel can be used as a wearable strain sensor and a skin electrode and has potential application prospects in the fields of human motion monitoring, Morse code signal transmission and real-time monitoring of human bioelectric signals.

Description

Technical Field

[0001] This invention relates to the field of eutectic gel materials technology, specifically to a method for preparing and applying a high-strength, high-toughness, high-conductivity silk fibroin micro / nano-fiber reconstructed eutectic gel. Background Technology

[0002] Eutectic gels are a novel type of ion-conducting gel material, composed of a cross-linked polymer network and an eutectic solvent. With their unique bio-like conductivity mechanism, wide temperature range stability, environmental friendliness, and low cost, they are gradually replacing traditional ion-conducting hydrogels and ion liquid gels, attracting significant attention in emerging fields such as smart sensing, health monitoring, electronic skin, and human-computer interaction. Compared to solvent displacement and supramolecular self-assembly methods, in-situ free radical polymerization based on polymerizable eutectic solvents (PDES) offers process controllability and ease of operation, making it a commonly used strategy for constructing eutectic gels. It is worth noting that when eutectic gels are used as soft ion conductors, they must simultaneously possess high ion conductivity and strong mechanical properties. However, the hydrogen-bonded dynamic network structure formed by in-situ polymerization of PDES has inherent defects such as low cross-linking density and weak intermolecular forces, resulting in poor gel mechanical properties (mechanical strength < 1 MPa, toughness < 5 MJ·m). -3 This makes it difficult to meet the needs of practical applications.

[0003] To prepare strong and tough eutectic gels, existing research has proposed various methods aimed at enhancing the gel network, such as physical / chemical crosslinking, multiple network structures (e.g., dual-network structures and interpenetrating polymer networks), and hybridization with nanomaterials (e.g., introducing rigid MXene nanosheets, cellulose nanocrystals, etc.). These methods improve the mechanical properties of eutectic gels by increasing the polymer network or crosslinking density and introducing energy dissipation mechanisms. Although eutectic gels prepared by the above methods exhibit excellent mechanical properties, such as high strength (> 1 MPa) and high toughness (> 20 MJ·m),... -3 However, their ionic conductivity is low, typically less than 0.1 S·m. -1 The ionic conductivity of eutectic gels is below the threshold for effective ion transport. To improve the ionic conductivity of eutectic gels, existing techniques typically introduce large amounts of eutectic solvents, additional water, or inorganic salts into the polymer network to establish conductive pathways. However, this may exacerbate the plasticizing effect of the polymer network, leading to a decrease in its mechanical properties. Therefore, there is an inherent contradiction between the ionic conductivity and mechanical properties of eutectic gels, which is difficult to balance. This stems from the antagonistic effect between the eutectic solvent and the polymer network, severely restricting the development and application of eutectic gels.

[0004] Furthermore, the polymerization process of PDES relies on a triple synergistic mechanism of chemical initiators, crosslinking agents, and high-energy ultraviolet irradiation, resulting in high complexity of the preparation process. Residual toxic initiators and crosslinking agents are detrimental to the sustainability and biocompatibility of eutectic gels. Chinese patent application CN115895157A proposes a method for preparing eutectic gels through in-situ polymerization of PDES directly initiated by sunlight. This method eliminates the need for any crosslinking agents or photoinitiators, filling a gap in green photopolymerization chemistry for functional gel material synthesis. However, it requires the introduction of an expensive ionic liquid ([Bmim]Cl) to regulate the balance between the mechanical properties and ionic conductivity of the eutectic gel. Therefore, developing a green, environmentally friendly, simple, and efficient preparation method to overcome the inherent contradiction of the difficulty in simultaneously improving the mechanical properties and ionic conductivity of eutectic gels, and to achieve a synergistic improvement in both, remains a challenge. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing and applying a high-strength, high-conductivity silk fibroin micro / nanofibrils reconstructed eutectic gel, thereby resolving the inherent contradiction of balancing the mechanical properties and ionic conductivity of eutectic gels. Firstly, based on the hydrogen bonding network and solvation effect of choline chloride / acrylic acid (ChCl / AA) type PDES, thermal stimulation causes in-situ depolymerization of silk fibroin fibers, forming silk fibroin micro / nanofibrils (SMNF) that are highly compatible with the system, serving as reinforcing units for the reconstructed gel network. Furthermore, liquid metal (EGaIn) microdroplets are used to directly induce in-situ polymerization of AA monomers in the SMNF-PDES mixture at room temperature to prepare SMNF-reconstructed eutectic gel (SMNF-Egel), achieving a synergistic improvement in the mechanical properties and ionic conductivity of the eutectic gel. This gel can be used in wearable strain sensors and epidermal electrodes, showing potential applications in human motion monitoring, Morse code signal transmission, and real-time monitoring of human bioelectrical signals.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a high-strength, high-toughness, and highly conductive silk fibroin micro / nano-fiber reconstructed eutectic gel includes the following steps:

[0008] Step 1: Preparation of silk fibroin micro / nano fibrils-polymerizable eutectic solvent mixture (SMNF-PDES mixture);

[0009] Step (1): Place the raw silkworm silk in a Na2CO3 aqueous solution for degumming treatment to obtain silk fibroin fiber;

[0010] Step (2): Mix the hydrogen bond acceptor and the hydrogen bond donor, stir and heat to obtain a polymerizable eutectic solvent (PDES).

[0011] Step (3): Take silk fibroin fibers, cut them into small pieces, add them to polymerizable eutectic solvent (PDES), and heat-stimulate them to obtain SMNF-PDES mixture;

[0012] Step 2: Preparation of silk fibroin micro / nano fibril reconstructed eutectic gel (SMNF-Egel);

[0013] Step (1): Add gallium indium alloy liquid metal (EGaIn) to acrylic acid (AA) and sonicate to obtain EGaIn-AA microdroplet dispersion;

[0014] Step (2): Weigh the EGaIn-AA microdroplet dispersion and add it to the SMNF-PDES mixture. Stir, pour into a mold, and polymerize to obtain a high-strength, high-conductivity silk fibroin micro / nano fiber reconstructed eutectic gel (SMNF-Egel).

[0015] Preferably, in step (1) of step one: the Na2CO3 aqueous solution is a Na2CO3 aqueous solution with a mass fraction of 0.5%; the solid-liquid ratio of raw silkworm silk to the Na2CO3 aqueous solution with a mass fraction of 0.5% is 10g:400-600mL.

[0016] Preferably, in step (1) of step one, the degumming conditions are: degumming at 95-100 ℃ for 30-60 min, and repeating the above degumming operation twice.

[0017] Preferably, in step (2) of step one: the hydrogen bond acceptor is preferably choline chloride (ChCl), and the hydrogen bond donor is preferably acrylic acid (AA).

[0018] Preferably, in step (2) of step one, the molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1:1.6-2.4.

[0019] Preferably, in step (2) of step one, the stirring and heating conditions are: stirring and heating at 80-100 ℃ for 15-60 min.

[0020] Preferably, in step (3) of step one, the conditions for heat stimulation treatment are: heat stimulation treatment at 90-120 ℃ for 2-12 h.

[0021] Preferably, in step (3) of step one: the content of silk fibroin fiber in the SMNF-PDES mixture is 0.2%-1% of the mass of PDES.

[0022] Preferably, in step (1) of step two, the mass ratio of gallium indium alloy liquid metal (EGaIn) to acrylic acid (AA) is 0.35-1.4:14.

[0023] Preferably, in step (1) of step two, the ultrasonic treatment conditions are: ultrasonic treatment is performed in an ice-water bath environment using a probe-type ultrasonic cell disruptor, with an ultrasonic power of 400-600 W and a time of 10-15 min.

[0024] Furthermore, during ultrasound treatment, one cycle is 3 seconds, including 2 seconds of ultrasound and 1 second of pause.

[0025] Preferably, in step (2) of step two, the mass ratio of the EGaIn-AA microdroplet dispersion to the SMNF-PDES mixture is 3.6:14.

[0026] Preferably, in step (2) of step two, the stirring time is 1-2 min.

[0027] Preferably, in step (2) of step two, the polymerization reaction conditions are: free radical polymerization at room temperature until gel is formed, and the polymerization time does not exceed 7 minutes.

[0028] Preferably, a high-strength, high-toughness, high-conductivity silk fibroin micro / nano-fiber reconstructed eutectic gel is prepared using the preparation method described above.

[0029] Preferably, the application of a high-strength, high-conductivity silk fibroin micro / nano fiber reconstructed eutectic gel as described above in human motion monitoring, Morse code signal transmission, and real-time monitoring of human bioelectric signals.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. The synergistic strategy of PDES thermally stimulated in-situ depolymerization of silk fibroin fibers and EGaIn-induced reconstruction proposed in this invention not only solves the problem of incompatibility between the added rigid nanofiller and the gel matrix interface, but also avoids dependence on chemical crosslinking agents, initiators and high-energy ultraviolet irradiation, providing a green, environmentally friendly, simple and efficient new strategy for constructing high-performance silk fibroin-based eutectic gels.

[0032] 2. The SMNF-Egel prepared by this invention possesses a dynamic bond-micro / nanofibril interlocking synergistic reinforcement structure, exhibiting strong and tough mechanical properties, including high fracture strength (1.25 MPa) and high toughness (23.09 MJ·m). -3 It also has a modulus that matches the skin (416.18 kPa); in addition, SMNF can stabilize and improve the dispersion of EGaIn microdroplets and optimize the gel microstructure to promote ion transport by acting as a "bridge" between conductive EGaIn microdroplets, thereby significantly enhancing the conductive network of SMNF-Egel and giving it high ionic conductivity (1.51 S / m).

[0033] 3. SMNF and EGaIn exhibit a significant synergistic effect in eutectic gels: On the one hand, SMNF forms coordination bonds with EGaIn through its surface polar groups (such as hydroxyl, amino, and carboxyl groups) and achieves stable dispersion of EGaIn microdroplets through its three-dimensional framework structure. This interfacial anchoring and physical confinement not only improves the stability of EGaIn in the system but also reduces interfacial impedance, ensuring the construction of a continuous electrically conductive network. On the other hand, the active Ga atoms on the EGaIn surface can trigger the free radical polymerization of AA monomers, and the adsorption and confinement effect of SMNF on EGaIn significantly enhances the efficiency of this interfacial reaction. Simultaneously, SMNF also reacts with Ga... 3+ Through synergistic crosslinking of PAA segments, a multi-scale network similar to the extracellular matrix was constructed. Thus, SMNF not only significantly improves the strength, toughness, and energy dissipation capacity of the gel as a mechanical framework, but also enhances its overall electrical conductivity through an ion / electron synergistic conductive network. This effectively overcomes the contradiction between the mechanical and electrical properties of eutectic gels, achieving a balance and optimization of both.

[0034] 4. Thanks to the excellent mechanical properties, high ionic conductivity, high adhesion strength (to skin) and bottom interface impedance of the SMNF-Egel prepared by this invention, SMNF-Egel can be used in the fields of flexible strain sensors and epidermal electrodes, and has important application value in the fields of wireless real-time monitoring of human motion and physiological electrical signals, Morse code signal transmission, etc. Attached Figure Description

[0035] Figure 1 These are optical photographs of choline chloride (ChCl), acrylic acid (AA), and the polymerizable eutectic solvent ChCl / AA type PDES prepared in this invention.

[0036] Figure 2 These are optical photographs of AA and the polymerizable eutectic solvent ChCl / AA type PDES prepared in this invention before and after being placed at -20°C for 24 hours.

[0037] Figure 3 This is a DSC curve of the polymerizable eutectic solvent ChCl / AA type PDES prepared in this invention;

[0038] Figure 4 This is the FTIR spectrum of the polymerizable eutectic solvent ChCl / AA type PDES prepared in this invention;

[0039] Figure 5 This invention relates to the polymerizable eutectic solvent ChCl / AA type PDES. 1 H NMR spectrum;

[0040] Figure 6These are microscopic morphology images of the silk fibroin fibers prepared according to the present invention;

[0041] Figure 7 This is a diameter distribution diagram of the silk fibroin fibers prepared according to the present invention;

[0042] Figure 8 This is a microscopic morphology diagram of the silk fibroin micro-nano fibrils (SMNF) formed by the depolymerization of silk fibroin fibers in Example 2 of the present invention;

[0043] Figure 9 This is a diameter distribution diagram of the silk fibroin micro-nano fibrils (SMNF) formed by the depolymerization of silk fibroin fibers in Embodiment 2 of the present invention;

[0044] Figure 10 This is a schematic diagram illustrating the depolymerization effect of the polymerizable eutectic solvent ChCl / AA type PDES on silk fibroin fibers in the embodiments and comparative examples of this invention.

[0045] Figure 11 These are FTIR characterization images of silk fibroin fibers and silk micro / nano fibrils (SMNF) in Example 2 of this invention;

[0046] Figure 12 These are XRD characterization images of silk fibroin fibers and silk micro / nano fibrils (SMNF) in Example 2 of this invention;

[0047] Figure 13 This is an optical photograph of the SMNF-PDES mixture prepared in Comparative Example 3 of this invention;

[0048] Figure 14 This is a schematic diagram of the preparation process and morphological characterization of EGaIn-AA microdroplets in this invention;

[0049] Figure 15 This is an optical microscope image of the EGaIn-AA microdroplets in this invention;

[0050] Figure 16 This is a particle size distribution diagram of EGaIn-AA microdroplets in this invention;

[0051] Figure 17 This is an optical photograph of the gelation process of the EGaIn-AA microdroplet-induced SMNF-PDES composite system in this invention;

[0052] Figure 18 This is a thermal imaging image of the reaction system during the EGaIn-AA microdroplet-induced polymerization process in this invention;

[0053] Figure 19 This is a graph showing the temperature change over time in the reaction system during the EGaIn-AA microdroplet-induced polymerization process of this invention.

[0054] Figure 20This is an optical photograph of the SMNF-Egel prepared in Example 6 of this invention;

[0055] Figure 21 These are three-dimensional laser confocal microscope images of the SMNF-Egel prepared in Example 6 of this invention;

[0056] Figure 22 These are SEM images of the SMNF-Egel prepared in Example 6 of this invention;

[0057] Figure 23 This is the EDS mapping image of the SMNF-Egel prepared in Example 6 of this invention;

[0058] Figure 24 This is a schematic diagram showing the color change after adding methyl orange (MO) to the two systems EGaIn-SMNF-PDES and SMNF-PDES in this invention;

[0059] Figure 25 It is the SMNF-Egel and AA monomer prepared in Example 6 of this invention. 1 H NMR spectrum;

[0060] Figure 26 These are the FTIR spectra of SMNF-Egel and Egel, AA monomers prepared in Example 6 of this invention;

[0061] Figure 27 This is the XPS spectrum of the SMNF-Egel prepared in Example 6 of this invention;

[0062] Figure 28 This is a schematic diagram of the reaction mechanism in which EA monomers undergo free radical polymerization and cross-linking to form a gel network in the SMNF-PDES system induced by EGaIn microdroplets in this invention;

[0063] Figure 29 These are optical photographs of the SMNF-Egel prepared in Example 6 under different tensile strains;

[0064] Figure 30 These are the stress-strain curves of SMNF-reconstructed low cogels with different contents prepared in the examples and comparative examples;

[0065] Figure 31 The bar charts show the tensile strength and strain of SMNF-reconstructed low cogels with different contents prepared in the examples and comparative examples;

[0066] Figure 32 The bar chart shows the elastic modulus and toughness values ​​of the SMNF-reconstructed low cogels prepared with different contents in the examples and comparative examples.

[0067] Figure 33These are optical photographs taken at room temperature before and after 30 days of storage of the SMNF-Egel prepared in Example 6 and before and after 24 hours of storage of the SMNF-PAA hydrogel prepared in Comparative Example 4.

[0068] Figure 34 This is a graph showing the mass changes of the SMNF-Egel prepared in Example 6 and the SMNF-PAA hydrogel prepared in Comparative Example 4 after being placed at room temperature for 30 days.

[0069] Figure 35 These are the TG curves of the SMNF-Egel prepared in Example 6 and the SMNF-PAA hydrogel prepared in Comparative Example 4.

[0070] Figure 36 These are DSC curves of the SMNF-Egel prepared in Example 6 and the SMNF-PAA hydrogel prepared in Comparative Example 4;

[0071] Figure 37 These are optical and thermal images of the SMNF-Egel prepared in Example 6 and the SMNF-PAA hydrogel prepared in Comparative Example 4 after being placed at -50 °C for 24 h.

[0072] Figure 38 This is a graph showing the mechanical properties of the SMNF-Egel prepared in Example 6 at different temperatures;

[0073] Figure 39 This is a graph showing the resistance change of the SMNF-Egel prepared in Example 6 during the cutting and healing process;

[0074] Figure 40 This is a schematic diagram of the self-healing behavior of the SMNF-Egel prepared in Example 6 in an LED lamp integrated circuit;

[0075] Figure 41 This is a graph showing the mechanical properties of the SMNF-Egel prepared in Example 6 at different healing times;

[0076] Figure 42 This is a tensile photograph of the SMNF-Egel prepared in Example 6 after 48 hours of healing;

[0077] Figure 43 These are Nyquist plots of SMNF-Egel prepared in the examples and comparative examples;

[0078] Figure 44 This is a histogram showing the conductivity of SMNF-Egel prepared in the examples and comparative examples;

[0079] Figure 45This is a comparison of the electrical conductivity and mechanical properties of the SMNF-Egel prepared in Example 6 with those of eutectic gels prepared by other strategies;

[0080] Figure 46 This is a test chart of the strain sensing performance of the SMNF-Egel prepared in Example 6;

[0081] Figure 47 This is a demonstration of the application of the SMNF-Egel strain sensor in wireless human motion monitoring in this invention: a schematic diagram of a wireless motion monitoring system for signal acquisition, processing and transmission;

[0082] Figure 48 It is a wireless motion monitoring system based on SMNF-Egel strain sensors for real-time motion monitoring;

[0083] Figure 49 This invention demonstrates the application of the SMNF-Egel sensor in Morse code information transmission: a schematic diagram of potential application scenarios for a Morse code translation system based on the SMNF-Egel sensor;

[0084] Figure 50 This is a schematic diagram illustrating the application of the SMNF-Egel sensor in a Morse code medical communication system according to the present invention.

[0085] Figure 51 These are digital photographs of the SMNF-Egel electrode of this invention adhering to the skin surface before and after stretching;

[0086] Figure 52 This is a curve showing the adhesion strength of SMNF-Egel to pigskin in this invention;

[0087] Figure 53 These are impedance analysis graphs of SMNF-Egel and commercial gel in this invention;

[0088] Figure 54 This is a demonstration diagram illustrating the application of the SMNF-Egel electrode in wireless monitoring of EMG and ECG signals in this invention;

[0089] Figure 55 The present invention uses SMNF-Egel electrodes to record continuous ECG signal images of volunteers in different scenarios, including working on a computer, walking, resting, and conducting experiments;

[0090] Figure 56 This is a schematic diagram of the synergistic strategy of in-situ depolymerization of silk fibroin fibers by PDES and induced polymerization by EGaIn in this invention to prepare SMNF-Egel;

[0091] In the picture:

[0092] Figure 4(a) represents ChCl, AA, and ChCl / AA type PDES at wavenumbers of 2800-3600 cm⁻¹. -1 (a) FTIR spectra of ChCl, AA, and ChCl / AA type PDES at wavenumbers of 1000-2000 cm⁻¹; (b) FTIR spectra of ChCl, AA, and ChCl / AA type PDES at wavenumbers of 1000-2000 cm⁻¹. -1 FTIR spectra;

[0093] Figure 6 (a) is an optical microscope image of silk fibroin fibers; (b) is a SEM image of silk fibroin fibers.

[0094] Figure 8 (a) is an optical microscope image of SMNF in Example 2, and the inset in (a) is an optical image of the silk fibroin micro / nano fiber-polymerizable eutectic solvent mixture (SMNF-PDES mixture) prepared in Example 2; (b) is a SEM image of SMNF in Example 2.

[0095] Figure 10 (a) is an optical photograph of the silk fibroin micro / nano fiber-polymerizable eutectic solvent mixture (SMNF-PDES mixture) prepared in Example 1; (b) is an optical microscope photograph of the SMNF-PDES mixture prepared in Example 1; (c) is a SEM image of SMNF in Example 1; (d) is an optical photograph of the SMNF-PDES mixture prepared in Example 3; (e) is an optical microscope photograph of the SMNF-PDES mixture prepared in Example 3; (f) is a SEM image of SMNF in Example 3; (g) is an optical photograph of the SMNF-PDES mixture prepared in Comparative Example 1; (h) is an optical microscope photograph of the SMNF-PDES mixture prepared in Comparative Example 1; and (i) is a SEM image of SMNF in Comparative Example 1.

[0096] Figure 11 In Example 2, (a) is the FTIR spectrum of silk fibroin and SMNF, (b) is the deconvolution result of the FTIR spectrum of SMNF amide I band, and (c) is the deconvolution result of the FTIR spectrum of silk fibroin amide I band.

[0097] Figure 12 In Example 2, (a) is the XRD pattern of silk fibroin and SMNF, (b) is the deconvolution result of the XRD pattern of SMN in Example 2, and (c) is the deconvolution result of the XRD pattern of silk fibroin in Example 2.

[0098] Figure 14 (a) is an optical photograph of bulk EGaIn in AA, and (b) is an optical photograph of EGaIn-AA microdroplet suspension;

[0099] Figure 25 In (a), SMNF-Egel and AA monomers are at chemical shifts of 0-8 ppm. 1 (a) 1H NMR spectrum; (b) SMNF-Egel and AA monomers at chemical shifts of 0.0–3.0 ppm. 1 H NMR spectrum;

[0100] Figure 27 (a) is the XPS spectrum of SMNF-Egel; (b) is the XPS spectrum of the Ga 3d peak of SMNF-Egel.

[0101] Figure 46 (a) shows the change in relative resistance of the SMNF-Egel prepared in Example 6 under different tensile strains (0%-1200%). ΔR / R 0 (b) shows the change in relative resistance of the SMNF-Egel prepared in Example 6 under small strain (5%-50%). ΔR / R 0 (c) is the relative resistance change (ΔR / R0) of the SMNF-Egel prepared in Example 6 under large strain (100%-500%); (d) is the response time of the SMNF-Egel prepared in Example 6 at 100% strain; (e) is the response time of the SMNF-Egel prepared in Example 6 during 1000 stretch-release cycles at 100% strain. ΔR / R 0 ;

[0102] Figure 48 (a) is a real-time monitoring image of finger flexion, (b) is a real-time monitoring image of wrist flexion, (c) is a real-time monitoring image of elbow flexion, and (d) is a real-time monitoring image of knee joint movement.

[0103] Figure 50 (a) is the Morse code corresponding to the 26 letters of the English alphabet; (b) is a schematic diagram of a sensor encoding “Ÿ” (quick bend) and “▃” (hold bend for 2 seconds) into Morse code signals based on finger bending movements; (c) is the “HELP” message conveyed by the patient through rhythmic finger bending; and (d) is the “SOS” message conveyed by the patient through rhythmic finger bending.

[0104] Figure 54(a) is an optical photograph of EMG signals acquired using the three-point method; (b) shows the EMG signals generated during fist clenching recorded by the SMNF-Egel electrode and a commercial gel electrode; (c) shows the signal-to-noise ratio generated during fist clenching recorded by the SMNF-Egel electrode and a commercial gel electrode; (d) is a schematic diagram of the integration of the SMNF-Egel electrode with a wireless ECG measurement module for wireless monitoring of ECG signals; (e) shows ECG signals acquired by a volunteer at rest using the SMNF-Egel electrode and a commercial gel electrode; (f) shows the ECG signal acquired by the SMNF-Egel electrode, displaying the P-QRS-T characteristic waveform; (g) shows the ECG signal acquired by the commercial gel electrode, displaying the P-QRS-T characteristic waveform; and (h) shows the T / R value and SNR of the ECG signals acquired by the SMNF-Egel electrode and the commercial gel electrode. Detailed Implementation

[0105] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0106] Example 1

[0107] This embodiment discloses a method for preparing a mixture of silk fibroin micro / nano fibrils and polymerizable eutectic solvent, comprising the following steps:

[0108] Step (1): Preparation of silk fibroin fibers;

[0109] 20 g of raw silkworm silk was placed in 1 L of 0.5% Na2CO3 aqueous solution and degummed at 100 °C for 30 min. The above degumming process was repeated twice to obtain silk fibroin fibers.

[0110] Step (2): Prepare polymerizable eutectic solvent (PDES);

[0111] 25 g of choline chloride (ChCl) and 25.7 g of acrylic acid (AA) were mixed and heated at 90 °C for 30 min to form a clear and transparent polymerizable eutectic solvent ChCl / AA type PDES.

[0112] Step (3): Prepare a mixture of silk fibroin micro / nano fibrils and polymerizable eutectic solvent (SMNF-PDES mixture).

[0113] Take 0.5g of silk fibroin fiber, cut it into small pieces, add it to 50g of polymerizable eutectic solvent ChCl / AA type PDES, and heat-stimulate it at 90 ℃ for 12 h to form a silk fibroin micro / nano fibrils-polymerizable eutectic solvent mixture (SMNF-PDES mixture).

[0114] Example 2

[0115] The difference from Example 1 is that the heat stimulation treatment conditions were changed when preparing the silk fibroin micro-nano fibrils-polymerizable eutectic solvent mixture: heat stimulation treatment at 100 °C for 5 h; other parameters and conditions are the same as in Example 1.

[0116] Example 3

[0117] The difference from Example 1 is that the heat stimulation treatment conditions were changed when preparing the silk fibroin micro / nano fiber-polymerizable eutectic solvent mixture: heat stimulation treatment at 110 °C for 4 h; other parameters and conditions are the same as in Example 1.

[0118] Example 4

[0119] This embodiment discloses a method for preparing a high-strength, high-toughness, high-conductivity silk fibroin micro / nano-fiber reconstructed eutectic gel, comprising the following steps:

[0120] Step 1: Preparation of silk fibroin micro / nano fibrils-polymerizable eutectic solvent mixture (SMNF-PDES mixture);

[0121] Take 0.1g of silk fibroin fiber, cut it into pieces, add it to 50g of polymerizable eutectic solvent ChCl / AA type PDES, and heat-stimulate it at 100℃ for 5 h to form a silk fibroin micro / nano fibrils-polymerizable eutectic solvent mixture (SMNF-PDES mixture).

[0122] The preparation methods of silk fibroin fiber and polymerizable eutectic solvent ChCl / AA type PDES are the same as in Example 1;

[0123] Step 2: Preparation of silk fibroin micro / nano fibril reconstructed eutectic gel (SMNF-Egel);

[0124] Step (1): Prepare EGaIn-AA microdroplet dispersion;

[0125] 0.7 g of gallium indium alloy liquid metal (EGaIn) was added to 14 g of acrylic acid (AA), and then ultrasonic treatment was performed in an ice-water bath using a probe-type ultrasonic cell disruptor to obtain EGaIn-AA microdroplet dispersion.

[0126] The ultrasonic treatment power was 400 W and the time was 10 min (one cycle was 3 s, including 2 s of ultrasound and 1 s of pause).

[0127] Step (2): Prepare silk fibroin micro / nano fibril reconstructed eutectic gel SMNF-Egel;

[0128] 3.6 g of EGaIn-AA microdroplet dispersion was added to 14 g of SMNF-PDES mixture, and the mixture was stirred rapidly with a glass rod for 2 min. The mixture was then poured into a polytetrafluoroethylene mold and polymerized at room temperature for 7 min to form a gel, thus obtaining the silk fibroin micro / nano fibril reconstructed eutectic gel SMNF-Egel, denoted as SMNF-Egel-0.2.

[0129] Example 5

[0130] The difference from Example 4 is that the amount of silk fiber added was changed to 0.3g when preparing the silk micro-nano fibrils-polymerizable eutectic solvent mixture; the prepared silk micro-nano fibrils reconstructed eutectic gel was denoted as SMNF-Egel-0.6; other parameters and conditions were the same as in Example 4.

[0131] Example 6

[0132] The difference from Example 4 is that the amount of silk fiber added was changed to 0.5g when preparing the silk fibroin micro-nano fibrils-polymerizable eutectic solvent mixture; the prepared silk fibroin micro-nano fibrils reconstructed eutectic gel was designated as SMNF-Egel-1; other parameters and conditions were the same as in Example 4.

[0133] Comparative Example 1

[0134] The difference from Example 1 is that the heat stimulation treatment conditions were changed when preparing the silk fibroin micro / nano fibrils-polymerizable eutectic solvent mixture: heat stimulation treatment at 130 °C for 2 h; other parameters and conditions are the same as in Example 1.

[0135] Comparative Example 2

[0136] The difference from Example 4 is that the amount of silk fibroin added is changed to 0g (i.e. no silk fibroin is added); the eutectic gel prepared is denoted as SMNF-Egel-0; other parameters and conditions are the same as in Example 4.

[0137] Comparative Example 3

[0138] The difference from Example 4 is that the amount of silk fiber added was changed to 0.7g when preparing the silk micro-nano fibrils-polymerizable eutectic solvent mixture; the prepared silk micro-nano fibrils reconstructed eutectic gel is denoted as SMNF-Egel-1.4; other parameters and conditions are the same as in Example 4.

[0139] Comparative Example 4

[0140] This comparative example discloses a method for preparing SMNF-PAA hydrogel, including the following steps:

[0141] Step 1: Take 0.5g of silk fibroin fiber, cut it into small pieces, add it to 50g of polymerizable eutectic solvent ChCl / AA type PDES, and heat-stimulate it at 100℃ for 5 h to form a mixture of silk fibroin micro / nanofibrils and polymerizable eutectic solvent (SMNF-PDES mixture). Vacuum filter, wash with water to remove residual PDES, freeze dry to obtain silk fibroin micro / nanofibrils SMNF.

[0142] The preparation methods of silk fibroin fiber and polymerizable eutectic solvent ChCl / AA type PDES are the same as in Example 1;

[0143] Step 2: Disperse 0.14 g of silk fibroin micro / nano fiber (SMNF) in 14 g of acrylic acid (AA) aqueous solution and stir at room temperature for 30 min to obtain SMNF-AA mixture;

[0144] In the acrylic acid aqueous solution, the molar ratio of acrylic acid to water is 2:1;

[0145] 3.6 g of EGaIn-AA microdroplets were added to 14 g of SMNF-AA mixture, and the mixture was stirred rapidly with a glass rod for 2 min. The mixture was then poured into a polytetrafluoroethylene mold and polymerized at room temperature to form a gel, thus obtaining SMNF-PAA hydrogel, denoted as SMNF-PAA.

[0146] The preparation method of the EGaIn-AA microdroplet dispersion is the same as that in Example 4.

[0147] Experimental data characterization and performance testing

[0148] like Figure 1 As shown, PDES is obtained by mixing ChCl and AA at a molar ratio of 1:2 at 90 °C. After cooling to room temperature, a transparent liquid eutectic solvent ChCl / AA type PDES is formed.

[0149] As shown in Figure 23, due to the strong hydrogen bond between AA and ChCl, PDES maintains its fluid liquid characteristics at temperatures as low as -20 °C, exhibiting typical eutectic solvent properties.

[0150] like Figure 3 As shown, the melting point of PDES was tested by DSC. T m As can be seen, the melting point Tm of PDES is approximately -8℃, which is lower than that of ChCl (T m = 302 ℃) and AA ( T m = 14 ℃) Melting point of a single component.

[0151] The chemical structure of PDES was characterized by FTIR and 1H NMR. Figure 4 a and Figure 4 b shows the FTIR spectra of ChCl, AA, and PDES, as follows: Figure 4 a and Figure 4 As shown in b, it is located at 1717 cm. -1 The characteristic peak of -COOH at this position originates from AA, indicating that the carboxyl group of AA in the PDES system exists in acid form rather than salt form after heating. Compared with pure AA, the characteristic peaks of -OH and -COOH in PDES shift to lower wavenumbers, indicating that a strong hydrogen bond is formed between AA and ChCl.

[0152] In addition, such as Figure 5 As shown, PDES 1 The absence of new proton peaks in the 1H NMR spectrum indicates that ChCl and AA did not react during the formation of PDES upon heating. Furthermore, the chemical shift of the carboxyl proton peak in PDES moved to a lower field, further confirming that ChCl and the carboxyl group of AA formed a strong hydrogen bond.

[0153] In summary, considering physical appearance, DSC curves, FTIR spectra, and 1 The characterization results of the 1H NMR spectrum confirmed the successful preparation of ChCl / AA type PDES.

[0154] Figure 6-9 These are microscopic morphology and diameter distribution diagrams of silk fibroin fibers before and after in-situ depolymerization by PDES. Figure 6-7 It refers to the microstructure and diameter distribution of untreated silk fibroin fibers, such as... Figure 6 As shown in b, it can be seen that the silk fibroin fibers are damaged to a certain extent during the Na2CO3 degumming process, forming defects on their surface, which is conducive to the subsequent penetration of PDES.

[0155] like Figure 7 As shown, based on SEM images, the diameter distribution of silk fibroin fibers was statistically analyzed using ImageJ software, and the average diameter was 11.96 μm.

[0156] Furthermore, ChCl / AA type PDES was used to heat-stimulate silk fibroin fibers at 100 °C, causing in-situ depolymerization to form SMNF. Figure 8 As shown in the illustration, a uniformly dispersed SMNF-PDES mixture can be formed after treatment at 100 °C for 5 h. Figure 8-9As shown, because the AA and ChCl molecules of PDES can penetrate into the interior of the fiber through defects on the surface of the silk fibroin, they disrupt the hydrogen bonds and hydrophobic interactions between the silk fibroin molecules, thereby breaking the silk fibroin into micro-nano fibrils with smaller diameters, with an average diameter of 1.04 μm. This avoids fiber aggregation and facilitates uniform dispersion in the PDES system.

[0157] Figure 10 This diagram illustrates the depolymerization effect of ChCl / AA type PDES, a polymerizable eutectic solvent, on silk fibroin fibers under different process conditions. Thermal stimulation temperature and time are key factors influencing the in-situ depolymerization of silk fibroin fibers by PDES to form SMNFs. Figure 10 As shown in Figure ac, when the temperature is reduced to 90 °C, even after 12 h of heat stimulation treatment, the silk fibroin fibers undergo partial depolymerization, with only a small number of micro-nano fibrils forming on their surface. This indicates that under the process conditions, PDES has a poor depolymerization effect on silk fibroin fibers.

[0158] like Figure 10 As shown in d and g, when the temperature increased to 110 °C and 130 °C, the time to form a paste-like SMNF-PDES mixture decreased to 4 h and 2 h, respectively. Although the depolymerization efficiency was significantly improved, the color of the SMNF-PDES mixture obtained at 110 °C and 130 °C gradually changed, because PDES dissolved some silk fibroin at high temperatures.

[0159] like Figure 10 As shown in the inset, especially at 130 °C, PDES dissolves silk fibroin, leading to a significant increase in system viscosity and even fiber formation, which is detrimental to the subsequent EGaIn microdroplet-induced polymerization reaction. Furthermore, as... Figure 10 As can be seen from ef, at 110 ℃, PDES dissolves some silk fibroin, causing the silk fibers to break into short rod-shaped micro / nanofibrils. At 130 ℃, nanofibrils are mainly formed. Figure 10 h), while some silk fibers are depolymerized into nanoparticles by PDES (h), Figure 10 (i) indicates that the mesoscopic structure of the silk fibroin fiber is disrupted. Considering energy consumption, depolymerization efficiency, and avoiding high-temperature damage to the silk fibroin fiber during depolymerization, the optimal conditions for PDEE depolymerization of silk fibroin fiber are 100 °C for 5 h.

[0160] Figure 11-12 These are molecular conformational characterization diagrams of silk fibroin fibers and SMNF. (Example:) Figure 11 As shown, FTIR was used to test and analyze the molecular conformation of silk fibroin fibers and SMNF. Figure 11 As can be seen from a, SMNF fibers have 1620 and 1695 cm in the amide I band. -1The characteristic peaks at 1515 and 1230 cm⁻¹ belong to β-sheet and β-turn structures, respectively, while those at 1515 and 1230 cm⁻¹ belong to β-sheet and β-turn structures, respectively. -1 The nearby characteristic peaks correspond to the β-sheet structure of the amide II band and the α-helical structure of the amide III band. Compared to silk fibroin fibers, the characteristic peak positions of SMNF did not change significantly, indicating that the two have similar secondary structures.

[0161] Further deconvolution processing was performed on the FT-IR spectra of silk fibroin and SMNF in the amide I region, and the results are as follows: Figure 11 As shown in figures b and c, the relative content of β-sheets in SMNF increases from 43.09% to 50.37%. Meanwhile, compared to silk fibroin fibers (51.46%), the relative content of random coils and α-helical conformations in SMNF decreases to 44.57%. These analyses indicate that PDES primarily disrupts the amorphous conformational network of silk fibroin molecules during in-situ depolymerization of silk fibroin to form SMNF, rather than the highly ordered β-sheet crystalline regions.

[0162] according to Figure 12 The XRD patterns of silk fibroin and SMNF in sample a show that the characteristic diffraction peaks at 2θ values ​​of 9.1° and 20.7° correspond to the silk II conformation of silk fibroin and SMNF, respectively, while the characteristic diffraction peaks at 2θ values ​​of 24.7° and 28.6° correspond to the silk I conformation. Importantly, the crystallization peaks of SMNF did not change significantly compared to silk fibroin, indicating that PDES effectively weakens the interfacial interactions between fibers without causing significant damage to the internal mesostructure of the fibers.

[0163] like Figure 12 As shown in figures b and c, the crystallinity of silk fibroin fibers and SMNF was calculated by deconvolving the XRD spectra. The crystallinity of SMNF was 57.57%, slightly higher than that of SF fibers (52.65%), further confirming that PDES did not destroy the β-sheet crystal structure during the depolymerization of silk fibroin fibers. In summary, the SMNF formed by in-situ depolymerization of silk fibroin fibers by PDES retains the original mesoscopic structure of natural silk, which is beneficial for the subsequent preparation of high-performance silk-based gel materials.

[0164] To investigate the effect of SMNF content on the mechanical properties and ionic conductivity of reconstructed eutectic gels, PDES was used to depolymerize silk fibroin fibers of different masses in situ, forming an SMNF-PDES mixture. It should be noted that, as... Figure 13As shown, in the SMNF-Egel-1.4 prepared in Comparative Example 3, it was difficult to obtain a uniformly dispersed SMNF-PDES mixture when the silk fibroin fiber content reached 1.4% of the PDES mass. Therefore, the silk fibroin fiber content was set to 0% - 1% of the PDES mass, and Examples 4, 5, 6 and Comparative Example 2 were further prepared.

[0165] Taking SMNF-Egel-1 prepared in Example 6 as an example, the process and mechanism of preparing SMNF-Egel by the synergistic strategy of PDES thermal stimulation of in-situ depolymerization of silk fibroin fibers and EGaIn-induced reconstruction were investigated.

[0166] Figure 14 This is a schematic diagram of the preparation process of EGaIn-AA microdroplets. Figure 15-16 This is a morphological characterization and particle size distribution diagram of EGaIn-AA microdroplets. (Example) Figure 14 As shown in a, EGaIn was chemically modified with AA monomer and dispersed under ultrasonic assistance to form an EGaIn-AA microdroplet suspension. Figure 14 b). Figure 15 Optical microscope photographs and Figure 16 The particle size distribution diagram shows that the blocky EGaIn in AA was broken into micron-sized particles under the action of ultrasound, with an average particle size of 2.51 μm.

[0167] Polymerization was initiated by adding EGaIn-AA microdroplets to the SMNF-PDES complex. Figure 17 As shown, the composite system began to gel at 5 min and formed a stable gel after incubation at room temperature for 7 min. Furthermore, the temperature change of the mixture was monitored using an infrared thermal imager to understand the gelation process. Figure 18-19 As shown, due to the release of a large amount of heat during the reaction, the temperature of the mixed system rose from 26.6 ℃ to 65.9 ℃ within 2 minutes. The infrared thermal imaging showed that the polymerization reaction first occurred locally, and then the heat was distributed and diffused throughout the gel matrix. This is a typical phenomenon of chain initiation and chain growth during free radical polymerization.

[0168] The SMNF-Egel prepared in Example 6 was analyzed by laser confocal microscopy, SEM, and EDS. Figure 20 The microstructure of the ) was characterized, and the results are as follows Figure 21-23 As shown. Figure 21 The images show three-dimensional laser confocal microscopy (SEM) images of SMNF-Egel. They reveal a typical fiber-reinforced composite structure, where SMNF (black) is embedded in the gel matrix (red) in a uniformly dispersed fibrous morphology, forming a tightly interwoven three-dimensional network. SEM images show no obvious interfacial partitioning or phase separation between SMNF and PDES, indicating that they form a continuous gel matrix.Figure 22 The EDS spectrum further showed that Ga, In, C, O, N, and Cl elements were uniformly distributed in the gel matrix. Figure 23 This indicates that EGaIn did not show significant aggregation.

[0169] To investigate the reaction mechanism of EGaIn-induced polymerization in the preparation of SMNF-Egel, the presence of free radicals in the reaction system was first confirmed through dye degradation experiments. Because free radicals have strong oxidizing properties, they can degrade dyes (such as methyl orange and MO). Figure 24 As shown, the SMNF-PDES system prepared in Example 6 is acidic. When MO solution is added to the composite system, it turns dark red. When EGaIn microdroplets are introduced into the SMNF-PDES system, the dark red color disappears after 1 min. This is because EGaIn reacts with the AA monomer in PDES to generate free radicals, which in turn destroy the chromogenic groups of MO.

[0170] Secondly, adopt 1 The chemical structure of SMNF-Egel was analyzed by 1H NMR, FTIR, and XPS. Figure 25 As shown, in the SMNF-Egel prepared in Example 6 1 In the 1H NMR spectrum, the characteristic peaks at 1.11 ppm and 2.42 ppm correspond to methylene and methine protons on the polyacrylic acid (PAA) backbone, respectively, indicating that the polymerization reaction produces a PAA network. Furthermore, SMNF-Egel exhibited characteristic peaks at 3.21, 3.54, and 4.07 ppm, which are attributed to ChCl in the system.

[0171] like Figure 26 As shown, in the FTIR spectrum, the value located at 1635 cm⁻¹ -1 The absorption peak corresponds to C=C in AA, and the peak disappears after the induced polymerization reaction, indicating that AA has successfully polymerized. Compared with the eutectic gel Egel without SMNF (i.e., SMNF-Egel-0 prepared in Comparative Example 2), the characteristic peaks of -OH and -COOH in SMNF-Egel shift to lower wavenumbers, indicating that strong hydrogen bonds are formed between SMNF and the PDES gel matrix. In addition, the absorption peak at 1627 cm⁻¹... -1 The absorption peak is due to Ga 3+ Coordinate bonds are formed between it and the carboxyl group.

[0172] like Figure 27 As shown, the XPS spectrum of SMNF-Egel reveals Ga 3d, In 3d, C 1s, O 1s, N 1s, and Ga 2p peaks. Furthermore, Ga 3d can be subdivided into Ga... 3+ and Ga 0The two main peaks further confirm the presence of Ga in SMNF-Egel. 3+ Mediated coordinate bonds.

[0173] In summary, we have summarized the reaction mechanism by which EGaIn induces in-situ polymerization of AA monomers and further crosslinks PAA chains to form a gel network, such as... Figure 28 As shown. First, under acidic conditions, H... + Capable of disrupting the Ga2O3 layer structure on the EGaIn surface. 3+ Simultaneously, under ultrasonic action, EGaIn is broken into microdroplets and released; the unpaired electrons of Ga atoms in the EGaIn microdroplets can react with the π-bonds in the AA monomers to form carbon free radicals, which in turn initiate the free radical polymerization of the remaining AA monomers to generate PAA chains; the carboxyl groups in the PAA chains can combine with amino acid groups, ChCl, and other PAA chains in SMMF through hydrogen bonds, while Ga... 3+ It forms coordination bonds with the carboxyl groups in SMNF and PAA. Therefore, the SMNF, PAA chains, and ChCl form coordination bonds with Ga through hydrogen bonds. 3+ The gel network is formed by multiple dynamic cross-linking, including mediated coordination bonds.

[0174] Figure 29-32 The image shows the mechanical property characterization diagram of SMNF-Egel. (From...) Figure 29 It is known that SMNF-Egel can withstand strains up to 2000% without fracturing, exhibiting excellent tensile properties. For example... Figure 30-31 As shown, the mechanical properties of SMNF-Egel can be controlled by changing the content of silk fibroin fibers; when the content of silk fibroin fibers increases from 0 to 1%, the tensile strength of SMNF-Egel increases from 0.15 MPa to 1.25 MPa, and the elongation at break increases from 1401% to 2289%; Figure 32 As shown, the elastic modulus and toughness of SMNF-Egel-1 are 416.18 kPa and 23.09 MJ·m, respectively. -3 The strength is approximately 7 times and 18 times that of SMNF-Egel-0, respectively. Therefore, the SMNF-Egel prepared in this invention exhibits significant advantages in fracture strength, fracture strain, and toughness, demonstrating high-strength and high-toughness mechanical properties.

[0175] To further verify the excellent mechanical properties of the SMNF-Egel prepared in the embodiments of the present invention, the mechanical properties of SMNF-Egel-1 prepared in Example 6 were compared with those of PDES-based eutectic gels with different reinforcement strategies reported in recent years. The specific test results are shown in Table 1:

[0176] Table 1

[0177]

[0178] Table 1 summarizes the comparison of the mechanical properties of SMNF-Egel-1 prepared in Example 6 of this invention with those of PDES-based eutectic gels reported in recent years. It can be seen that, compared with the reinforcement strategies reported in the literature (such as dual-network structures, cellulose reinforcement, doping with liquid metal nanoparticles, and physical / chemical crosslinking), the SMNF-Egel-1 prepared in Example 6 of this invention has significant advantages in fracture strength, fracture strain, and toughness, exhibiting high strength and toughness mechanical properties. Therefore, unless otherwise specified, SMNF-Egel-1 will be used in subsequent performance and application studies.

[0179] Figure 33-42 This is a characterization diagram of the environmental stability and self-healing ability of SMNF-Egel. Environmental stability is crucial for the practical application of eutectic gels. Due to the low freezing point and low vapor pressure of the eutectic solvent, SMNF-Egel will exhibit significant resistance to drying and freezing. Figure 33 Optical photographs of SMNF-PAA hydrogel and SMNF-Egel after 1 day and 30 days at room temperature, respectively. Figure 34 It can be seen that even after being placed at room temperature for 30 days, SMNF-Egel still has good flexibility, with a weight loss rate of only 3.04%; in contrast, SMNF-PAA hydrogel is severely dehydrated after only 1 day, with a weight loss rate of 33.70%, and is prone to breakage after stretching.

[0180] The thermal stability of SMNF-Egel and SMNF-PAA hydrogels was analyzed by TG, and the results are as follows: Figure 35 As shown, at 200℃, the weight loss rate of SMNF-Egel was 9.87%, while that of SMNF-PAA hydrogel was as high as 43.61%, indicating that SMNF-Egel has excellent thermal stability and applicability over a wide temperature range.

[0181] Furthermore, the heat resistance of SMNF-Egel and SMNF-PAA hydrogels was tested using DSC. Figure 36 As shown, the SMNF-PAA hydrogel exhibits a significant exothermic peak at -7.9℃, indicating that the hydrogel begins to freeze at this temperature. In contrast, the SMNF-Egel does not exhibit any exothermic peak in the range of -80℃ to 100℃, indicating that the SMNF-Egel does not freeze and has excellent antifreeze properties. Figure 37 This visually demonstrates the advantages of eutectic gels in terms of freeze-thaw resistance. Compared to SMNF-PAA hydrogel, SMNF-Egel did not freeze after being placed at -50 ℃ for 24 h and can still withstand various mechanical deformations such as bending, torsion, and tension. Furthermore, stress-strain curves at different temperatures are also presented. Figure 38It can be seen that SMNF-Egel has good mechanical properties even at -50 ℃.

[0182] In summary, SMNF-Egel exhibits excellent environmental stability, including resistance to drying, thermal stability, and freeze-thaw resistance. This is mainly due to the rich hydrogen bond network of the gel network, which not only locks in the solvent but also withstands high temperatures and significantly lowers the freezing point, allowing SMNF-Egel to maintain stability and functionality in harsh environments.

[0183] Because the SMNF-Egel network prepared in this invention contains a large number of reversible hydrogen bonds and Ga... 3+ Multiple interactions, including mediated coordination bonds, endow it with excellent self-healing properties. The self-healing ability of SMNF-gel was investigated from both electrical and mechanical perspectives. Figure 39 This shows the real-time change in resistance of SMNF-Egel during the cut-repair cycle. Once cut, the resistance of SMNF-Egel immediately becomes infinite; however, when the two gel segments are reconnected, the resistance immediately returns to its original value. Figure 40 As shown, integrating SMNF-Egel into a circuit visually demonstrates this electrical repair process: after the two gel segments recombine, the LED bulb lights up again; when they separate, the bulb turns off. Figure 41 The mechanical properties of SMNF-Egel at different repair times were characterized by tensile testing. Both tensile stress and tensile strain increased with prolonged repair time. Although the tensile strain of the rebonded gel failed to recover to the level of the uncut sample, its tensile stress recovered to a maximum of 1.24 MPa, comparable to that of the original sample. Figure 42 This further demonstrates that the repaired SMNF-Egel can withstand large deformations without breaking.

[0184] The conductivity and strain sensing performance of SMNF-Egel were further investigated, and the results are as follows: Figure 43-45 As shown. First, the effect of silk fibroin fiber content on the conductivity of SMNF-Egel (size: 10 mm × 10 mm × 2 mm) was studied using electrochemical impedance spectroscopy (EIS). Figure 43 As can be seen, the impedance of SMNF-Egel decreases with increasing silk fibroin fiber content (0-1%). Conductivity calculations for different SMNF-Egels show that when the silk fibroin fiber content increases from 0 to 1%, the conductivity of SMNF-Egel increases from 0.56 S / m to 1.51 S / m. Figure 44The increased conductivity of SMNF-Egel due to the increased content of micro / nano fibrils is due to the following reasons: 1) SMNF surfaces have functional groups such as -OH, -NH2, and -COOH. These functional groups interact with ions in PDES through hydrogen bonds and electrostatic attraction, forming transport channels on their surfaces that facilitate rapid ion migration; 2) The micro / nano fibril network framework can restrict the mobility and aggregation of EGaIn droplets, helping EGaIn to be more uniformly dispersed and connected in the gel matrix, reducing "breakpoints" in the conductive network, and providing additional electron transport paths; 3) The abundant functional groups (-OH, -NH2, -COOH) of silk fibroin can undergo physical adsorption or chemical bonding with the EGaIn surface, enhancing the interfacial compatibility between EGaIn and the matrix and reducing interfacial resistance. Therefore, compared to other strategies for improving the conductivity of eutectic gels, such as introducing DES (see reference Adv. Funct. Mater. 2024, 34, 2411029. DOI: 10.1002 / adfm.202411029), water molecules (see reference Int. J. Biol. Macromol. 2025, 311, 143914. DOI: 10.1016 / j.ijbiomac.2025.143914), inorganic salts (see reference Polymer, 2023, 283,126238. DOI: 10.1016 / j.polymer.2023.126238) and zwitterions (see reference ACS Nano, 2024, 18, 18980. DOI: (e.g., 10.1021 / acsnano.4c02661), the SMNF-Egel prepared by this invention not only exhibits high electrical conductivity but also demonstrates strong mechanical properties. Figure 45 ).

[0185] Thanks to the robust mechanical properties and high conductivity of SMNF-Egel, its strain sensing performance was further tested. Figure 46 a represents the relative resistance change of SMNF-Egel ( Δ The relationship curve between R / R0 and tensile strain was calculated using piecewise linear fitting. ΔR / R 0 - The slope of the tensile strain curve represents the strain sensing sensitivity (GF). It can be seen that the sensitivities of SMNF-Egel-1 are 1.58, 3.06, and 4.44 in the strain ranges of 0-400%, 400-900%, and 900-1200%, respectively, exhibiting both a wide strain sensing range and high sensitivity. Figure 46As shown in bc, SMNF-Egel exhibits repeatable and regular electrical signal responses under both small strains (5%, 10%, 30%, 50%) and large strains (100%, 200%, 300%, 400%, 500%). ΔR / R 0 The value increases with increasing strain, confirming its reliable sensing performance. Furthermore, the response time and recovery time of SMNF-Egel at 100% strain are 404 ms and 384 ms, respectively. Figure 46 d) ensures the accuracy and real-time nature of the detection. This is achieved by tracking 1000 stretch-release cycles at 100% strain. ΔR / R 0 The durability of SMNF-Egel was evaluated using signals, and the results were as follows: Figure 46 As shown in e. Although the baseline drifts slightly due to mechanical hysteresis, ΔR / R 0 The signal indicates that SMNF-Egel-1 has good stability.

[0186] To demonstrate the application of SMNF-Egel as a wearable strain sensor in wireless human motion monitoring, the SMNF-Egel-1 prepared in Example 6 was first cut into strips measuring 30 mm × 10 mm × 2 mm. Then, commercial copper conductive tape was used to adhere the SMNF-Egel-1 to corresponding areas of the volunteer's body (e.g., wrist, elbow, fingers, and knee). Copper wires were then used to connect the SMNF-Egel sensor to a wireless dynamic resistance testing module (TruEbox, LinkZill) integrated circuit, which was connected to a smartphone via Bluetooth to monitor the resistance signals generated by the aforementioned body parts during movement in real time. Furthermore, commercial copper conductive tape was used to adhere the SMNF-Egel sensor to the volunteer's finger joints and connect it to the wireless resistance testing module. A spike was generated immediately upon finger 90° bending, and a square wave pattern was generated after holding the 90° bend for 2 seconds, representing the Morse code symbols "●" and "▃" respectively, demonstrating the application of information transmission.

[0187] Benefiting from its excellent mechanical compliance, high sensitivity, fast response, and wide strain sensing range, the SMNF-Egel strain sensor has broad application prospects in the field of human motion monitoring. To further verify its practicality, a wireless motion monitoring system was built based on the SMNF-Egel strain sensor, including signal acquisition, processing, and Bluetooth-based wireless transmission functions. Figure 47As shown, this system is capable of real-time acquisition, transmission, processing, encoding, and Bluetooth-based wireless transmission of strain sensor signals generated by human motion, as well as real-time monitoring via a dedicated mobile application. Therefore, this system achieves real-time monitoring and wireless transmission of strain signals, strongly demonstrating its applicability in wireless motion sensing. Figure 48 As shown, the system can dynamically capture and track motion signals in various motion states such as finger, wrist, elbow and knee flexion.

[0188] Besides monitoring changes in electrical signals, signal transmission is also crucial in real-life scenarios. Therefore, this invention demonstrates the application of the SMNF-Egel sensor in a Morse code medical communication system. For example... Figure 49 As shown, the sensor is placed near the knuckle. The different electrical signals generated by the bending of the finger are collected and processed by the signal processing device and sent to the smart client for analysis via Bluetooth. Figure 50 The display shows the Morse code sequence corresponding to the 26 letters of the English alphabet. A finger bent at 90° and immediately returned to its original position represents the Morse code symbol "●", while a finger bent at 90° and held for 2 seconds before returning to its original position represents the symbol "▃". Figure 50 b). Therefore, by combining these signals into predefined waveforms corresponding to the letters, continuous bending movements can form coherent phrases. For example, as... Figure 50 As shown in the diagram, patients can send emergency messages such as "HELP" and "SOS" to doctors via simple finger gestures, enabling remote, silent diagnosis. This technology rapidly conveys critical needs without verbal communication, thus improving patient safety. Its wireless design reduces reliance on the physical presence of caregivers, thereby lowering hospitalization costs and workload, highlighting the transformative potential of conductive eutectic gels in driving the development of telemedicine and smart healthcare systems. In summary, these findings fully demonstrate the practical application potential and broad applicability of SMNF-Egel sensors in human motion monitoring and information transmission.

[0189] 15 mm diameter, 2 mm thick circular SMNF-Egel electrodes were integrated with electrode clips to fabricate SMNF-Egel electrodes for monitoring EMG and ECG signals. For EMG testing, a three-point method was used, with the detection electrode attached to the forearm muscle bundle and the reference electrode placed at the wrist. The gel epidermal electrodes were connected to the EMG Pro electromyography sensing module (Runyi Taiyi Technology Co., Ltd.) via wires. The acquired EMG data could be quickly transmitted to a mobile phone or computer via a high-efficiency Bluetooth module, enabling wireless real-time monitoring of electrical signals generated by muscle movement. For ECG monitoring, two circular SMNF-Egel electrodes were integrated with a wireless ECG module (Runyi Taiyi Technology Co., Ltd.) and attached to the volunteer's chest to collect ECG signals at rest, which were then transmitted to a smartphone via Bluetooth. Furthermore, real-time monitoring and wireless transmission of ECG signals were performed on volunteers in various scenarios, including working at a computer, walking, resting, and conducting experiments.

[0190] An SMNF-Egel electrode for monitoring physiological electrical signals was fabricated by integrating the SMNF-Egel with an electrode clip. Figure 51 As shown, the electrode can adhere tightly to the skin under external force and can quickly recover after release, effectively alleviating potential damage to the skin electrode interface and preventing detachment due to excessive weight of the monitoring device.

[0191] Using pigskin instead of human skin, the adhesion strength between SMNF-Egel and skin was quantitatively characterized by an overlap shear test. The adhesion strength between SMNF-Egel and pigskin was 77.54 kPa. Figure 52 This self-adhesive property ensures seamless and conformal contact between the SMNF-Egel and the skin, which is beneficial for its stable signal output as a flexible electrode.

[0192] Furthermore, EIS analysis was performed on SMNF-Egel, and it was compared with commercial gel electrodes. Figure 53 It is known that the impedance of SMNF-Egel is lower than that of commercial gels. For example, at 100 Hz, the impedance of SMNF-Egel is 299 Ω, which is significantly lower than that of commercial gels (1362 Ω). This is beneficial for establishing a low-impedance interface between the SMNF-Egel electrode and human skin to obtain accurate physiological electrical signals.

[0193] EMG signals reflect the clinical status and activity of muscles and are widely used in human-machine interfaces (such as prostheses and machine-assisted living). For wireless monitoring of EMG signals, two SMNF-Egel electrodes are attached to the forearm muscle bundles, and a third SMNF-Egel electrode is placed at the wrist, connected to the wireless EMG Pro electromyography sensing module via wires. Figure 54a). For example Figure 54 As shown in b, compared to commercial gel electrodes, the SMNF-Egel electrode can effectively acquire EMG signals generated by muscle movement during fist clenching, with higher signal quality and lower signal noise. The signal-to-noise ratio (SNR) of the SMNF-Egel electrode is 24.68 dB, which is higher than that of commercial gel electrodes (SNR is 22.476 dB). Figure 54 c).

[0194] Continuous ECG signals are crucial for the early detection and diagnosis of heart disease. As a proof of concept, this invention integrates SMNF-Egel electrodes with a wireless ECG module to develop a wireless ECG monitoring system, which is attached to the left chest of a volunteer. Figure 54 d) Monitor the ECG signal of volunteers in a resting state in real time and transmit it to a smartphone via Bluetooth. Figure 54 Comparing the ECG signals recorded by the SMNF-Egel electrode and commercial gel electrodes in the resting state, it can be seen that the SMNF-Egel electrode can acquire high-quality ECG signals with clear P-QRS-T characteristic ECG peaks. Simultaneously, the interval between consecutive R peaks is approximately 0.94 s, corresponding to a heart rate of 64 beats / min (bpm). Figure 54 (fg), which meets the standards for normal healthy adults. The sensitivity of the ECG signal is defined as the ratio of the relative intensities of the T peak to the R peak. The calculated T / R value of the SMNF-Egel electrode is 0.234, which is higher than that of commercial gel electrodes (0.185). Figure 54 h). Signal-to-noise ratio (SNR) reflects the noise level of a signal and, from another perspective, characterizes the quality of an ECG signal. Figure 54 h showed that the SNR of the SMNF-Egel electrode was 30.08, higher than that of commercial electrodes (26.79). Therefore, the SMNF-Egel electrode can provide a more reliable and sensitive signal for clinical cardiac diagnosis. To further investigate the ability of the SMNF-Egel electrode to perform long-term continuous monitoring in daily life, a wireless ECG monitoring system was attached to the left chest of another relatively obese volunteer (weight: 75 kg, height: 173 cm), and its ECG signal was continuously monitored in different scenarios. Figure 55 It is known that the SMNF-Egel electrode was able to accurately record the volunteer's ECG signals under different activity states, including working on a computer (heart rate 94 bpm), walking (heart rate 115 bpm), resting (84.5 bpm), and conducting experiments (94 bpm). In normal individuals, the heart rate at rest and during work is between 60 and 100 bpm, and should be below 120 bpm when walking. Figure 55The data showed that the volunteers' heart rates were within the normal range during the test, confirming the application potential of the SMNF-Egel electrode in daily health monitoring.

[0195] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-strength, high-toughness, high-conductivity silk fibroin micro / nano-fiber reconstructed eutectic gel, characterized in that, Includes the following steps: Step 1: Preparation of silk fibroin micro / nano fibers-polymerizable eutectic solvent mixture; Step (1): Place the raw silkworm silk in a Na2CO3 aqueous solution for degumming treatment to obtain silk fibroin fiber; Step (2): Mix the hydrogen bond acceptor and the hydrogen bond donor, stir and heat to obtain a polymerizable eutectic solvent; The hydrogen bond acceptor is choline chloride, and the hydrogen bond donor is acrylic acid; the molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1:1.6-2.

4. Silk fibroin fibers were cut into small pieces, added to a polymerizable eutectic solvent, and subjected to heat stimulation treatment to obtain a mixture of silk fibroin micro-nano fibrils and polymerizable eutectic solvent. The heat stimulation treatment conditions were as follows: heat stimulation treatment at 90-120 ℃ for 2-12 h; in the silk fibroin micro / nano fibrils-polymerizable eutectic solvent mixture, the content of silk fibroin fibers was 0.2%-1% of the mass of the polymerizable eutectic solvent. Step 2: Preparation of high-strength, high-toughness, high-conductivity silk fibroin micro / nano-fiber reconstructed eutectic gel; Step (1): Add gallium indium alloy liquid metal to acrylic acid and sonicate to obtain gallium indium alloy liquid metal-acrylic acid microdroplet dispersion; The mass ratio of gallium-indium alloy liquid metal to acrylic acid is 0.35-1.4:

14. Step (2): Weigh gallium indium alloy liquid metal-acrylic acid microdroplet dispersion and add it to the mixture of silk fibroin micro-nano fibrils-polymerizable eutectic solvent. Stir, pour into a mold, and polymerize to obtain high-strength, high-toughness, high-conductivity silk fibroin micro-nano fibrils reconstructed eutectic gel. The mass ratio of gallium indium alloy liquid metal-acrylic acid microdroplet dispersion to silk fibroin micro-nano fiber-polymerizable eutectic solvent mixture is 3.6:14; the stirring time is 1-2 min; the polymerization reaction conditions are: free radical polymerization reaction at room temperature until gel formation, and the polymerization time does not exceed 7 min.

2. The method for preparing the high-strength, high-toughness, high-conductivity silk fibroin micro / nano-fiber reconstructed eutectic gel according to claim 1, characterized in that, In step (1) of step one: the Na2CO3 aqueous solution is a Na2CO3 aqueous solution with a mass fraction of 0.5%; the solid-liquid ratio of raw silkworm silk to the Na2CO3 aqueous solution with a mass fraction of 0.5% is 10g:400-600mL; the degumming treatment conditions are: degumming treatment at 95-100 ℃ for 30-60 min, and repeating the above degumming treatment operation twice.

3. The method for preparing the high-strength, high-toughness, high-conductivity silk fibroin micro / nano-fiber reconstructed eutectic gel according to claim 1, characterized in that, In step (2) of step one, the stirring and heating conditions are: stirring and heating at 80-100 ℃ for 15-60 min.

4. The method for preparing the high-strength, high-toughness, high-conductivity silk fibroin micro / nano-fiber reconstructed eutectic gel according to claim 1, characterized in that, In step (1) of step two: the ultrasonic treatment conditions are: ultrasonic treatment is carried out in an ice water bath environment, the power of ultrasonic treatment is 400-600 W, and the time is 10-15 min. One cycle consists of 3 seconds, including 2 seconds of ultrasound and 1 second of pause.

5. A high-strength, high-toughness, high-conductivity silk fibroin micro / nano-fiber reconstructed eutectic gel prepared by the preparation method of the high-strength, high-toughness, high-conductivity silk fibroin micro / nano-fiber reconstructed eutectic gel as described in any one of claims 1-4.

6. The application of the high-strength, high-conductivity silk fibroin micro / nano fiber reconstructed eutectic gel as described in claim 5 in human motion monitoring, Morse code signal transmission, and real-time monitoring of human physiological electrical signals.

Images