A high-sensitivity bending sensor based on ionic polymer gel

Abstract

The application discloses a high-sensitivity bending sensor based on ionic polymer gel and belongs to the technical field of flexible sensors. The high-sensitivity bending sensor based on ionic polymer gel comprises an ionic gel central sensitive layer with a double-network structure and electrode layers attached to surfaces of the ionic gel central sensitive layer in pairs, and the number of pairs of the electrodes is greater than or equal to 1; preferably, the number of pairs of the electrodes is greater than or equal to 2; wherein the ionic gel central sensitive layer is formed into the double-network structure with interwound molecular chains through cross-linking polymerization of monomers of zwitterionic polymers and monomers of flexible polymers. The device disclosed by the application exhibits multi-degree-of-freedom bending characteristics, has high bending response sensitivity and a wide response range, can identify bending directions and amplitudes, and has a wide application prospect in the field of human-computer interaction.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flexible sensors, and particularly relates to a high-sensitivity bending sensor based on an ionomer gel. BACKGROUND

[0002] With the development of artificial intelligence, wearable electronic devices have shown great market prospects and are widely used in human motion monitoring, biological medicine, virtual reality and military fields. As a core device of flexible wearable electronic devices, it has the characteristics of lightness, thinness, portability and good conformability with the human body, and has attracted people's attention. Flexible bending sensors are flexible electronic devices that can convert the bending changes they bear into easy-to-collect and easy-to-transmit electrical signals, thereby accurately recording the bending deformation of the monitored object in real time. They have broad application prospects in the field of human-computer interaction.

[0003] Although the resistance type, capacitance type and piezoelectric type bending sensors developed in the early stage can realize the detection of bending deformation, they have low sensitivity and cannot distinguish bending direction and angle. Some researchers have designed a resistance type bending sensor with a reverse pyramid structure to suppress micro-cracks in the specified area under bending, which helps the sensor to detect large-scale bending strain, but the sensor cannot distinguish the bending direction (Document 1). In order to enable the sensor to respond to bending in different directions, some researchers have proposed a resistance type sensor with gradient structure dispersion characteristics of active material in polyurethane, in which the gradient structure is realized by gravity-driven self-assembly, and the active material uses tannic acid modified MXene nanosheets. The asymmetry of the film gives it a response to directional bending, but the sensor has the disadvantage of small sensitivity (Document 2).

[0004] Therefore, it is of great significance to develop a bending sensor with high sensitivity and bending direction and angle recognition capability.

[0005] Prior art documents:

[0006] Document 1: Lee D H, Yang J C, Sim J Y, et al. Bending Sensor Based on Controlled Microcracking Regions for Application toward Wearable Electronics and Robotics [J]. ACS applied materials & interfaces, 2022, 14(27): 31312-31320.

[0007] Document 2: Bai J, Gu W, Bai Y, et al. Multifunctional Flexible Sensor Based on PU-TA@MXene Janus Architecture for Selective Direction Recognition [J]. Advanced Materials 2023, 2302847. SUMMARY

[0008] In view of the deficiencies of the prior art, the present application provides a high-sensitivity bending sensor based on ionic polymer gel. The device exhibits multi-degree-of-freedom bending characteristics, has high bending response sensitivity and wide response range, can identify bending direction and amplitude, and has broad application prospects in the field of human-computer interaction. To achieve the above purpose, the present application adopts the following technical solutions:

[0009] In the first aspect, the present application provides a high-sensitivity bending sensor based on ionic polymer gel. The high-sensitivity bending sensor based on ionic polymer gel comprises an ionic gel central sensitive layer with a double network structure and an electrode layer attached to the surface of the ionic gel central sensitive layer in pairs, and the number of pairs of electrodes is ≥1; preferably, the number of pairs of electrodes is ≥2; wherein the ionic gel central sensitive layer is formed by cross-linking and polymerization of zwitterionic polymer monomers and flexible polymer monomers to form a double network structure with interwoven molecular chains. When the number of pairs of electrodes is 1, the bending direction and amplitude detection in one degree of freedom can be realized. When the number of pairs of electrodes is greater than or equal to 2, multi-degree-of-freedom bending detection can be realized.

[0010] Preferably, the electrode layer is attached to the upper surface and the lower surface of the strip-shaped ionic gel central sensitive layer in pairs to form a sandwich structure sensor that realizes one-degree-of-freedom direction recognition.

[0011] Preferably, the electrode layer is attached to the four side walls of the strip-shaped ionic gel central sensitive layer in pairs to form a long strip structure sensor that realizes two-degree-of-freedom direction recognition.

[0012] Preferably, the electrode layer is rectangular or topologically optimized to form a serpentine shape; preferably, the topologically optimized serpentine-shaped electrode layer is attached to the four side walls of the strip-shaped ionic gel central sensitive layer in pairs to form a long strip structure sensor that realizes two-degree-of-freedom direction bending recognition.

[0013] Preferably, the double network structure comprises an elastic polymer backbone formed by polymerization of flexible polymer monomers and a poly-zwitterion channel formed by zwitterionic polymers; preferably, the monomer of the zwitterionic polymer is methacrylic acid sulfobetaine, and the monomer of the flexible polymer is acrylamide.

[0014] Preferably, the ionic precursor solution of the ionogel center sensitive layer further comprises a free ion source and a solvent in addition to the monomers of the zwitterionic polymer and the flexible polymer; wherein the anions and cations provided by the free ion source can move freely in the polyelectrolyte channel; preferably, the cations of the free ion source are smaller in size than the anions. It is advisable that the sizes of the anions and cations have a certain difference. Smaller cations have faster migration speed, while the anions have slower migration speed than the cations due to their larger size. Therefore, the greater the size difference between the anions and cations, the greater the potential difference formed on both sides of the electrode, thereby improving the sensitivity of the device. The greater the size difference between the anions and cations of the free ion source of the ionogel center sensitive layer, the greater the difference in migration rate under bending strain, and the greater the potential difference formed, the higher the response sensitivity of the sensor device.

[0015] Preferably, the free ion source is selected from one or more of zinc triflate, lithium triflate, and lithium chloride; and the solvent is selected from at least one of water, an organic solvent, and a deep eutectic solvent, preferably water.

[0016] Preferably, the electrode layer comprises a flexible substrate and a conductive material coated on the surface of the flexible substrate; the conductive material is selected from one or more of a specific microstructured metal thin film, metal particles, carbon nanotubes, metal nanowires, graphene, MXene, and a conductive polymer; preferably, the conductive material is deposited on the surface of the flexible substrate to obtain the electrode layer. The electrode layer has high conductivity, flexibility, ductility, and electrical conductivity stability under bending strain. High conductivity is conducive to the rapid transmission of electrical signals. Excellent flexibility facilitates the co-compatibility of the electrode and the ion polymer layer, improving the stability of the interface charge transfer.

[0017] Preferably, the high-sensitivity bending sensor based on ion polymer gel senses bending by the potential difference formed by the asymmetric movement of the anions and cations of the free ion source caused by bending.

[0018] Preferably, the high-sensitivity bending sensor based on ion polymer gel further comprises an encapsulation layer covering the surface of the sensor; preferably, the material of the encapsulation layer is selected from polyethylene terephthalate, polyimide, polydimethylsiloxane, polymethyl methacrylate, or silicone rubber. The encapsulation layer has good modulus adaptation with the ionogel center sensitive layer and the electrode layer, can achieve better bending deformation, and has a protective effect and a solvent blocking effect, which can effectively prevent the evaporation of the solvent in the ionogel center sensitive layer, improve the stability of the ion polymer gel material, and prolong the service life of the sensor.

[0019] In a second aspect, the present application provides the high-sensitivity bending sensor based on the ionic polymer gel as described in any one of the above, and the preparation method comprises: forming and curing an ionic precursor solution of the ionic gel central sensitive layer to obtain the ionic gel central sensitive layer; and attaching the electrode layer in pairs on the surface of the ionic gel central sensitive layer to obtain the high-sensitivity bending sensor based on the ionic polymer gel. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The sensing mechanism diagram of the high-sensitivity bending sensor based on the ionic polymer gel of the present application.

[0021] Figure 2 The scanning electron microscope micrographs of the single-network PAM hydrogel and the double-network P(SBMA-AM) hydrogel.

[0022] Figure 3 The cyclic tensile stress-strain curve of the P(SBMA-AM)-Zn(TFSI)2 ionic gel of Example 1 of the present application.

[0023] Figure 4 The curve of the resistance value of the electrode of Example 1 of the present application changing with the number of bending.

[0024] Figure 5 The geometric diagram of the test platform of the high-sensitivity bending sensor based on the ionic polymer gel of the present application.

[0025] Figure 6 The comparison of the voltage output of the high-sensitivity bending sensor based on the ionic polymer gel prepared in Examples 1-3 of the present application at a bending angle of 90°.

[0026] Figure 7 The electrical signal output of the ionic flexible bending sensor prepared in Example 14 of the present application when bending in the X and Y directions.

[0027] Figure 8 The structural diagram of the ionic flexible bending sensor prepared in Example 14 of the present application. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be further described below in combination with the drawings and through specific embodiments, and it should be understood that the embodiments are only used to illustrate the present application and should not be regarded as specific limitations of the present application.

[0029] The following will be described in combination with Figure 1 The high-sensitivity bending sensor based on the ionic polymer gel (which can also be referred to as an ionic flexible bending sensor) of the present application will be described.

[0030] The high-sensitivity bending sensor based on the ionomer gel comprises an ion gel central sensitive layer (also referred to as an ion polymer layer) with a double network structure and a pair of electrode layers attached to the surface of the ion gel central sensitive layer, and the number of pairs of electrodes is greater than or equal to 1; preferably, the number of pairs of electrodes is greater than or equal to 2; wherein the ion gel central sensitive layer is formed by cross-linking polymerization of the monomers of zwitterionic polymers and the monomers of flexible polymers to form a double network structure with intertwined molecular chains. Through the design of the double network structure, physical and chemical cross-linking is introduced into the ion gel central sensitive layer, and the mechanical properties thereof are regulated, so that the ion gel with small residual strain and good resilience is obtained, the bending deformation of multiple degrees of freedom can be realized, the fatigue life is long, and the repeated use stability of the device is beneficial.

[0031] The structure of the ion-type flexible sensor comprises a sandwich structure for realizing one-degree-of-freedom direction recognition and a strip structure for realizing two-degree-of-freedom direction recognition.

[0032] In some technical solutions, the electrode layers are attached in pairs to the upper surface and the lower surface of the strip-shaped ion gel central sensitive layer to form a sandwich structure sensor for realizing one-degree-of-freedom direction recognition. In a specific embodiment, the electrode layers are attached to the upper and lower surfaces of the gel film to form a sandwich structure sensor.

[0033] In some technical solutions, the electrode layers are attached in pairs to the four side walls of the strip-shaped ion gel central sensitive layer to form a strip structure sensor for realizing two-degree-of-freedom direction recognition.

[0034] The shape of the electrode layer includes but is not limited to a rectangle and a topologically optimized snake shape. In a preferred embodiment of the present application, the topologically optimized snake-shaped electrode layer is attached to the four side walls of the strip-shaped ion gel central sensitive layer to form a strip structure sensor for realizing two-degree-of-freedom direction bending recognition. The topologically optimized snake-shaped electrode layer is attached to the four walls of the strip-shaped ion gel central sensitive layer, and can more freely realize multi-dimensional deformation, including in-plane and out-of-plane bending.

[0035] The double network structure comprises an elastic macromolecular skeleton formed by monomers of a flexible polymer and a polyzwitterion channel formed by a zwitterionic polymer. The elastic macromolecular skeleton provides the ionic polymer gel with suitable mechanical strength and elasticity. The zwitterionic polymer forms the polyzwitterion channel while regulating the mechanical properties of the gel, and enhances the ion transport capacity of the material by means of electrostatic interaction. Specifically, the zwitterionic polymer has a pair of cationic and anionic groups in its repeating unit (here, the cationic and anionic groups refer to the zwitterionic groups of the zwitterionic polymer itself, as distinguished from the movable cations and anions provided by a free ion source), and exhibits equal charge stoichiometry and uniform charge distribution at the molecular level. The zwitterionic groups in the zwitterionic polymer interact with water molecules to form active centers, weaken the interaction between the migrating ions and the polymer chains, and reduce the resistance of the ions in the transmission. In addition, the zwitterionic groups provide migration channels through electrostatic interaction, respectively, and accelerate the transmission of electrolyte ions, so that the polyzwitterion hydrogel has good conductivity. Meanwhile, the cations and anions provided by the free ion source can freely move in the ion channel.

[0036] The ionic gel central sensitive layer of the present application has flexibility, good elasticity, adhesion, and high ionic conductivity. The flexibility enables the device to realize multiple modes of deformation. The elasticity is a key indicator for the repeated use of the device. The high adhesion strength between the ionic gel central sensitive layer and the electrode layer is a key to realizing a good and stable interface combination of the device. The high ionic conductivity indicates that the ionic gel central sensitive layer has good ion transport capacity, which is conducive to the improvement of the sensitivity of the sensor. To meet these conditions, the ionic precursor solution of the ionic gel central sensitive layer comprises, in addition to the monomers of the zwitterionic polymer and the monomers of the flexible polymer, a free ion source and a solvent. In some technical solutions, the mass ratio of the monomers of the zwitterionic polymer, the monomers of the flexible polymer, the free ion source, and the solvent is 1-2:3-6:0.5-20:5-40.

[0037] The monomers of the zwitterionic polymer not only have high adhesion performance, but also provide migration channels for ions. Due to the strong electrostatic repulsion between the zwitterionic segments, the network structure is loose, and the pore size is increased, which is more conducive to the transmission and migration of ions in the polymer network. The anionic and cationic groups in the zwitterionic polymer interact with water molecules to form active centers, weaken the interaction between the ions and the polymer chains, and thus accelerate the ion migration and improve the ionic conductivity. Preferably, the monomers of the zwitterionic polymer are methacrylic acid sulfobetaine.

[0038] The monomers of the flexible polymer serve to provide the gel with suitable mechanical strength and elasticity to meet the mechanical deformation requirements. Preferably, the monomers of the flexible polymer are acrylamide.

[0039] In a preferred embodiment, the mass ratio of acrylamide (AM) to methacrylic sulfobetaine (SBMA) is (3-5): 1. For example, when the mass ratio of acrylamide to methacrylic sulfobetaine in the ionic gel used in the sensor is 3: 1, it has the highest sensitivity.

[0040] The free ion source provides movable (migrating) anions and cations. Preferably, the cations of the free ion source are smaller in size than the anions. The smaller size cations and larger size anions are selected so that the small size cations move faster, shortening the response time. Preferably, the cations and anions of the free ion source differ greatly in size. The large size difference enhances the response sensitivity of the device.

[0041] The free ion source can be selected from zinc trifluoromethylsulfonylimide (Zn(TFSI)2), lithium trifluoromethylsulfonylimide (Li(TFSI)), lithium chloride (LiCl), or other ionic salts. The free ion source does not react with the polymer monomers of the ionic gel central sensitive layer, nor does it react with the materials of the electrode layer.

[0042] The solvent is selected from at least one of water, an organic solvent, and a deep eutectic solvent, and is preferably water.

[0043] In a preferred embodiment, the P(SBMA-AM) composite ionic hydrogel containing Zn(TFSI)2has the most excellent performance. A P(SBMA-AM) double network structure with good mechanical properties is formed in the gel system through physical and chemical crosslinking. The presence of Zn(TFSI)2ions provides ionic interactions, in which Zn 2+ The polyvalent cations provide physical crosslinking for the polymer chains, and the TFSI - The induced salting-out effect enhances the inter-chain interaction, and the synergistic effect of ion-induced crosslinking and salting-out toughens the hydrogel, further enhancing the mechanical properties of the gel, with the smallest residual strain and good resilience, which is the key to the repeated use of the device. Due to the presence of the zwitterionic group in SBMA, the salt can be dissociated to produce charged ions, and these charged anions and cations (as well as the zwitterionic group) all have interaction forces such as hydrogen bonding, electrostatic, and ionic dipole with the substrate, so that Zn(TFSI)2provides more and stronger interactions, exhibiting higher adhesion, and thus has the most stable and excellent interface bonding. The transmission and diffusion charge capacity of the Zn(TFSI)2ions in the gel system in the electrode material is superior to other ions, which provides an answer to its superior sensing performance.

[0044] The electrode layer includes a flexible substrate and a conductive material coated on the surface of the flexible substrate.

[0045] In some embodiments, the flexible substrate is selected from thermoplastic polyurethane (TPU) fiber membrane, polytetrafluoroethylene (PTFE) filter membrane, mixed cellulose (GSWP) filter membrane, polydimethylsiloxane (PDMS) film, silicone rubber (Ecoflex) film, or other flexible organic polymer materials.

[0046] Preferably, the flexible substrate is selected from thermoplastic polyurethane (TPU) fiber membrane. It not only has good modulus matching with the ion gel, but also has low resistance (1.190 Ω / cm). As an example, the thickness of the TPU fiber membrane is 10-200 μm, and the diameter of the TPU fiber is 1-2 μm. In a preferred embodiment of the present application, the thickness of the TPU fiber membrane is 50 μm, and the diameter of the TPU fiber is 1.5 μm.

[0047] The conductive material includes, but is not limited to, a specific microstructured metal thin film, metal particles, carbon nanotubes, metal nanowires, graphene, MXene, conductive polymers, or other low-dimensional conductive materials. In some embodiments, the resistance of the conductive material is less than 100 Ω / cm.

[0048] The conductive material is deposited on the surface of the flexible substrate to form a conductive layer. The conductive layer has high conductivity and flexibility. The thickness of the conductive layer can be varied as needed. For example, the thickness of the conductive layer is 100-500 nm. In a preferred embodiment of the present application, the thickness of the conductive layer is 200 nm.

[0049] The electrode layer described in the present application has high conductivity, high elasticity, and conductivity stability under large strain. High conductivity is a prerequisite for the electrode to collect high-precision electrical signals, and high flexibility is the key to the electrode not being damaged under bending deformation. Compared with other combinations of flexible substrates and conductive materials, the electrode layer of the present application has higher conductivity and flexibility. In specific embodiments, the resistance of the electrode remains relatively stable after multiple cycles of bending, slightly increasing from 1.190 Ω / cm initially to 1.308 Ω / cm after 10,000 cycles, with a resistance change rate of less than 10%.

[0050] The electrode layer selected in the present application has high conductivity, flexibility, and ductility, and can be conformally attached to the central sensitive layer of the ion gel, adapting to the bending and deformation of the gel material, and maintaining conductivity stability during bending and deformation. Such electrode layer design is beneficial to the device to obtain higher sensitivity, faster response speed, and better device stability.

[0051] Figure 1is the sensing mechanism diagram of the ion-type flexible bending sensor. The sandwich-type sensor is composed of two electrode layers and an ion polymer layer. When the sensor is not bent, the ions are uniformly distributed in the ion gel central sensitive layer, and the potential difference on both sides of the ion gel central sensitive layer is zero. When the sensor is bent, one side will be stretched and expanded, and the other side will be compressed. This will cause the ions to migrate from the compression area to the expansion area, and due to the different sizes of the anions and cations, the migration speed is different, and positive and negative potentials will be accumulated on both sides of the sensor electrodes. Therefore, the ion-type sensor can not only generate an electrical signal without external power supply, but also can be used to distinguish different bending strain directions.

[0052] In terms of sensing principle, the present application uses the potential difference formed by the asymmetric motion of anions and cations of the free ion source caused by bending for bending sensing. The potential difference is closely related to the bending angle and amplitude, providing feasibility for multi-degree-of-freedom sensing. In terms of device structure, the present application uses ion gel as the central sensitive layer, and deposits multiple pairs of electrodes on it. The potential difference between each pair of electrodes is closely related to the bending angle and curvature, and by analyzing the signal difference between multiple pairs of electrodes, the bending direction and amplitude can be quickly identified. The present application solves the problem that existing bending sensors are difficult to distinguish bending angles.

[0053] The ion gel central sensitive layer used in the ion-type sensor of the present application has good mechanical properties and high ionic conductivity. The ion gel central sensitive layer is a polymer material with high viscosity, which can be closely attached to the electrode material, which is conducive to realizing good and stable interface bonding, thereby improving the sensing performance. Moreover, the electrode layer of the ion-type sensor of the present application has low modulus, which can conform well with the high-flexibility ion polymer material, which is conducive to reducing the contact impedance between the electrode layer and the ion polymer layer, realizing high-quality electrical signal transmission, and also realizing multi-degree-of-freedom bending and tensile strain detection. Based on the above-mentioned excellent material design, the prepared sensor has ultra-high sensitivity, good stability, wide detection range and small detection limit, and can realize high-frequency response and distinguish different bending directions.

[0054] In particular, the double-network gel involved in the present application comprises an elastic polymer skeleton formed by polymerization of a flexible polymer monomer and a polyzwitterion channel formed by a zwitterionic polymer. The elastic polymer skeleton provides the ion polymer gel with suitable mechanical strength and elasticity, so that it can meet the mechanical deformation requirement. The zwitterionic polymer not only regulates the mechanical properties of the gel, but also forms a polyzwitterion channel to improve the ion transport capacity of the material by means of active center. In addition, the introduction of zwitterions also endows the gel with excellent adhesion, and the interface adhesion capacity is improved by the multiple interactions between the abundant ion groups in the gel and the material surface and the anions and cations.

[0055] The following exemplary illustrates the preparation method of the high-sensitivity bending sensor based on the ionomer gel according to the present application.

[0056] The electrode layer is prepared. The preparation method of the electrode layer includes but is not limited to filtration, spraying, vacuum evaporation.

[0057] The electrode layer is prepared by, for example, depositing metal particles on the TPU fiber film through vacuum evaporation. The method of vacuum evaporation allows the metal nanoparticles to be uniformly deposited on the TPU fiber film, and the resistance and thickness of the flexible conductive layer prepared are relatively uniform. In a preferred embodiment, silver particles are selected, and a silver nanoparticle layer is prepared on the TPU fiber film by vacuum evaporation. The amount of silver particles is, for example, 1.5-4.5 mg / cm 2 .

[0058] As an example, 5 g of thermoplastic polyurethane (TPU) is first dissolved in 20 g of N,N-dimethylformamide (DMF) to prepare a spinning solution with a mass fraction of 20%, and a TPU fiber film is prepared by electrospinning. Then, metal silver material is uniformly deposited on the TPU polymer flexible substrate by evaporation. In a specific embodiment, the thickness of the flexible substrate layer is 50 μm, and the thickness of the conductive layer is 200 nm.

[0059] The ion gel central sensitive layer is prepared. The preparation method of the ion gel central sensitive layer is one-pot method. The monomers of the flexible polymer, the monomers of the zwitterionic polymer, and the solvent are uniformly mixed, and then the free ion source is added and stirred for a period of time. Then, the initiator is added and continues to stir for a period of time to obtain a solution. After the solution is uniformly mixed, it is poured into a mold for curing. After cooling, the mold is removed and cut into an ion gel central sensitive layer. The curing conditions include but are not limited to thermal curing and photocuring. In a preferred embodiment, thermal curing is used. The initiator is preferably potassium persulfate (KPS). The curing time can be 9 h.

[0060] The order of preparing the electrode layer and preparing the ion gel central sensitive layer is not limited.

[0061] The electrode layer is attached to the surface of the ion gel central sensitive layer to prepare a high-sensitivity bending sensor based on the ionomer gel.

[0062] In some technical solutions, a conductive tape is arranged on part of the surface of the conductive layer, and conductive silver paste is coated to extend the gap between the conductive layer and the conductive tape and conductively connect them, so that effective electrical signal transport is generated between the electrode layer and the external circuit.

[0063] The device is encapsulated and applied to sensing monitoring. The material of the encapsulation layer can be selected from polyethylene terephthalate, polyimide, polydimethylsiloxane, polymethyl methacrylate or silicone rubber. The encapsulation layer has flexibility, ductility and solvent barrier properties. Preferably, the encapsulation layer is silicone rubber.

[0064] In summary, the sensor of the present application is a flexible bending sensor with high sensitivity and multiple degrees of freedom bending detection. The ionic flexible bending sensor of the present application has a good and stable interface bonding: on the one hand, the zwitterionic groups in the ionic gel center sensitive layer will produce hydrogen bonding, electrostatic, ionic dipole and other interaction forces with the electrode layer, showing high adhesion ability and firmly adhering to the surface of the electrode layer; on the other hand, the low modulus electrode material has good modulus matching with the ionic polymer material, and is not easy to fall off during bending. The stable interface bonding is conducive to obtaining higher sensitivity, faster response speed and better device stability of the device. Moreover, the preparation method of the sensor of the present application is simple in operation and low in cost, and has potential to be widely applied in human activity monitoring (such as upward and downward bending, inward and outward rotation of the wrist) and human-computer interaction field, realizes multiple degrees of freedom bending recognition, and has very important research value.

[0065] In the present application, the influence of free ion source and zwitterionic polymer on the sensitivity of the sensor is studied. Firstly, the size difference between the anion and cation of the free ion source. The cation with smaller radius has faster migration speed, while the anion with larger radius has slower migration speed than the cation, so the greater the size difference between the anion and cation, the greater the potential difference formed on both sides of the electrode, thereby improving the sensitivity of the device. Secondly, the charge number of the ion, the greater the charge number, the higher the potential difference output, and the higher the sensitivity. Finally, the adhesion of the gel after adding zwitterionic polymer monomer, mainly using the hydrogen bonding, electrostatic force, ion-dipole, cation-π bonding interaction force between the rich ion groups in the gel and the anion and cation and the material surface, thereby enhancing the adhesion strength, improving the interface bonding, enhancing the ion interaction effect, obtaining stronger signal, and realizing high-sensitivity detection.

[0066] The following further illustrates the embodiments to further illustrate the present application. It should also be understood that the following embodiments are only used to further illustrate the present application, and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present application are within the protection scope of the present application. The specific process parameters in the following examples are only one example in the appropriate range, i.e. those skilled in the art can select within the appropriate range according to the description herein, and are not limited to the specific values in the following examples.

[0067] Example 1

[0068] The ionomer gel-based high-sensitivity bending sensor according to the present application is prepared according to the following process steps:

[0069] (1) Ionomer layer preparation: 1.5 g of acrylamide (AM), 0.5 g of methacrylic acid sulfobetaine (SBMA) and 10 mL of deionized water are uniformly mixed, then 6.26 g of Zn(TFSI)2 is added and stirred for 0.5 hours; then 4 mg of N,N'-methylene bisacrylamide (MBAA) and 20 mg of potassium persulfate (KPS) are added and stirred for 1 hour to obtain a transparent solution; after the solution is uniformly mixed, it is ultrasonically treated at 20-30°C for 3 min; finally, it is injected into a self-made mold and heat cured for 9 h; after cooling, the mold is removed and cut into an ionomer strip of 40x15x2 mm.

[0070] (2) Electrode layer preparation: 5 g of thermoplastic polyurethane (TPU) is dissolved in 20 g of N,N-dimethylformamide (DMF) to prepare a 20% mass fraction of spinning solution, and a TPU fiber membrane is prepared as a polymer flexible substrate by electrospinning; then, 0.45 g of metal silver particle material is uniformly deposited on a 10x10 cm TPU polymer flexible substrate by vacuum evaporation to obtain a TPU / Ag electrode material; the electrode material is cut into a rectangle of 80x10 mm, a 5 mm wide copper-nickel conductive tape is arranged on part of the surface of the conductive layer, and conductive silver paste is coated to fill the pores to prepare an electrode layer.

[0071] (3) Assembly: the electrode layer is attached to the upper and lower surfaces of the ionomer layer respectively to prepare an ion-type bending sensor with a sandwich structure.

[0072] (4) Packaging: finally, the device is packaged with silicone rubber and applied to sensing and monitoring.

[0073] Figure 3 The cyclic tensile stress-strain curve of the P(SBMA-AM)-Zn(TFSI)2 ion gel is shown. By constructing a double network structure, physical and chemical cross-linking are introduced into the hydrogel, where the formation of covalent bonds in chemical cross-linking can provide suitable mechanical properties for the gel, and the generation of intermolecular hydrogen bonds, electrostatic forces and ion-dipole interactions in physical cross-linking can achieve energy dissipation, reduce residual strain and form a gel with good flexibility. According to the experimental results, the ion gel with Zn(TFSI)2 shows very small residual strain (0.92%), indicating that the gel as an ionomer matrix has very good elasticity, meeting the demand for repeated use of the sensor.

[0074] Sensitivity is one of the main performance parameters of flexible strain sensors and is crucial for their application. The strain coefficient (sensitivity, S) can be defined as: S = ΔV × ε -1 , where ΔV is the change in voltage under strain, ΔV=V-V0, and ε is the strain of the sensor.

[0075] Figure 5 A geometrical schematic diagram of the test platform for the long-range stable ion-type flexible bending sensor prepared in Example 1 is shown. Euler-Bernoulli theory is used to build a model to calculate the strain under the corresponding displacement.

[0076] The sensor was fixed to a PET film with an initial free length of 5 cm. The two ends of the PET film were then fixed between an electric translation stage, and a computer-controlled stepper motor was used to control the film's displacement and speed. The tensile-bending strain was calculated using MATLAB software based on Euler-Bernoulli theory. The electrodes were connected to an electrochemical station, and the open-circuit voltage change at both ends of the electrodes during the bending process was measured.

[0077] The thin-film sensor has a thickness of h and a length of L. When the displacement platform moves by x, the thin film bends. Assuming the central angle of the curve is θ, the radius is R. Based on geometric relationships, the following equations are derived:

[0078] θ×R=L

[0079]

[0080] Given L and x, θ and R can be obtained from the equation.

[0081] In this invention, the bending angle is 180° - θ. Finally, the bending strain is calculated using the Euler-Bernoulli approximation theory to obtain the strain corresponding to the displacement.

[0082]

[0083] Example 2

[0084] The highly sensitive bending sensor based on ionomer gel involved in this invention is prepared according to the following process steps:

[0085] (1) Ionic polymer layer preparation: 1.5 g of acrylamide (AM), 0.5 g of methacrylic acid sulfobetaine (SBMA) and 10 mL of deionized water were uniformly mixed, then 2.87 g of Li(TFSI) was added and stirred for 0.5 h; then 4 mg of N,N'-methylene bisacrylamide (MBAA) and 20 mg of potassium persulfate (KPS) were added and stirred for 1 h to obtain a transparent solution; the solution was uniformly mixed and then ultrasonicated at 20-30 °C for 3 min; finally, it was injected into a self-made mold and heat cured for 9 h; after cooling, the mold was removed and cut into 40 x 15 x 2 mm ionic polymer strips.

[0086] Steps (2)-(4) refer to Example 1.

[0087] Example 3

[0088] The high-sensitivity bending sensor based on ionic polymer gel according to the present application was prepared according to the following process steps:

[0089] (1) Ionic polymer layer preparation: 1.5 g of acrylamide (AM), 0.5 g of methacrylic acid sulfobetaine (SBMA) and 10 mL of deionized water were uniformly mixed, then 2.87 g of Li(TFSI) was added and stirred for 0.5 h; then 4 mg of N,N'-methylene bisacrylamide (MBAA) and 20 mg of potassium persulfate (KPS) were added and stirred for 1 h to obtain a transparent solution; the solution was uniformly mixed and then ultrasonicated at 20-30 °C for 3 min; finally, it was injected into a self-made mold and heat cured for 9 h; after cooling, the mold was removed and cut into 40 x 15 x 2 mm ionic polymer strips.

[0090] Steps (2)-(4) refer to Example 1.

[0091] The adhesion performance test method is as follows: the adhesion strength is measured by a pressure gauge (M5-20, Mark-10, America), a compression pre-stress of 20 N is first applied between the electrode material and the gel, and after 20 s, the pressure gauge is separated at a moving rate of 50 mm / min, and the tensile adhesion strength is determined by the following formula:

[0092]

[0093] where F is the peak force (tensile force is negative) read by the force gauge during movement, indicating the moment when the gel film and the electrode film are separated. S is the area of the electrode and the gel film in contact, which is a circle with a diameter of 1.2 cm.

[0094] The adhesion strength of the ionomer layer prepared in Examples 1-3 to the electrode layer was 24.1 kPa, 22.9 kPa, 20.3 kPa, respectively. Among them, the P(SBMA-AM) ionic gel containing Zn(TFSI)2 prepared in Example 1 showed the strongest adhesion, so it was most closely combined with the electrode material, and correspondingly, the sensing performance was also the most superior.

[0095] Figure 4 The change curve of the resistance of the electrode of Example 1 under bending cycle is shown. The electrode material not only maintains good stability under bending state, but also has fatigue resistance and long service life, and still maintains relative stability after multiple cycle bending, and the resistance of the electrode slightly rises from the initial 1.190 Ω / cm to 1.308 Ω / cm after 10000 cycles. The electrode still has high conductivity under multiple bending strains, and the specific reason is that the flexible substrate TPU substrate in the electrode layer has good flexibility and fiber network structure, and can still maintain the conductive path unbroken under multiple bending.

[0096] Figure 6 The voltage output change of the high-sensitivity bending sensor based on ionomer gel prepared in Examples 1-3 under a bending angle of 90° is shown. Among them, the sensor using P(SBMA-AM) ionic gel containing Zn(TFSI)2 of Example 1 showed the highest voltage output value of 395 mV; the voltage output value of the sensor using P(SBMA-AM) ionic gel containing LiCl of Example 3 was 210 mV; and the voltage output value of the sensor using P(SBMA-AM) ionic gel containing Li(TFSI) of Example 2 was 173 mV. The calculation formula of the sensitivity is: S = ΔV x ε -1 , where ΔV is the change of voltage under strain, ΔV = V-V0, and ε is the strain of the sensor. Therefore, the sensor using P(SBMA-AM) ionic gel containing Zn(TFSI)2 of Example 1 has the highest sensitivity (126 mV / 1% strain).

[0097] Example 4

[0098] The high-sensitivity bending sensor based on ionomer gel according to the present application is prepared according to the following process steps:

[0099] (2) Electrode layer preparation: 5 g of thermoplastic polyurethane (TPU) was dissolved in 20 g of N,N-dimethylformamide (DMF) to prepare a 20% mass fraction of the spinning solution, and a TPU fiber film was prepared as a polymer flexible substrate by electrospinning. Then, 1 mg of carbon nanotubes was uniformly deposited on a TPU polymer flexible substrate with a diameter of 5 cm by suction filtration to obtain a TPU / carbon nanotube electrode material. The electrode material was cut into a 50x10 mm rectangle, and a copper-nickel conductive tape with a width of 5 mm was arranged on part of the surface of the conductive layer, and conductive silver paste was coated to fill the gaps, to prepare the electrode layer.

[0100] Steps (1), (3) and (4) refer to Example 1.

[0101] Example 5

[0102] The high-sensitivity bending sensor based on ionomer gel according to the present application was prepared according to the following process steps:

[0103] (2) Electrode layer preparation: 1 mL of silver nanowire solution (concentration 1 mg / mL) was dispersed in 20 mL of alcohol to obtain a silver nanowire dispersion; then the silver nanowire (AgNWs) dispersion was uniformly sprayed onto a clean aluminum foil with a size of 10x10 cm using a spray gun, and the aluminum foil was placed on a heating table at 80°C during the spraying process; the aluminum foil with AgNWs loaded on the surface was cut into an electrode rectangular strip with a size of 60x10 mm to prepare the electrode layer.

[0104] (3) Assembly: The ionomer film was stretched to 60x20x2 mm, and the surface of the electrode rectangular strip with silver nanowires was attached to the ionomer film; then the aluminum foil was gently torn off, so that the silver nanowires were completely transferred to the ionomer film; a copper-nickel conductive tape with a width of 5 mm was arranged on part of the surface of the conductive layer, and conductive silver paste was coated to fill the gaps, to prepare the ion-type bending sensor.

[0105] Steps (1) and (4) refer to Example 1.

[0106] Example 6

[0107] The high-sensitivity bending sensor based on ionomer gel according to the present application was prepared according to the following process steps:

[0108] (2) Electrode layer preparation: 221 μL of Ti3C2T x / AgNPs (10 wt%) solution with a concentration of 2.26 mg / mL was dispersed in 20 mL of alcohol to obtain a dispersion; then GSWP was used as a filter membrane and a flexible substrate, and Ti3C2T x / AgNPs were uniformly deposited on the surface of the filter membrane; the surface of the filter membrane loaded with Ti3C2Tx The flexible substrate of / AgNPs was cut into an electrode rectangular strip of 50x10mm, a 5mm-wide copper-nickel conductive tape was arranged on part of the surface of the conductive layer, and conductive silver paste was coated to fill the gaps, to prepare the electrode layer.

[0109] Steps (1), (3) and (4) refer to Example 1.

[0110] Example 7

[0111] The high-sensitivity bending sensor based on ionomer gel according to the present application was prepared according to the following process steps:

[0112] (2) Electrode layer preparation: 1 mL of silver nanowire solution (concentration 1 mg / mL) was dispersed into 20 mL of alcohol to obtain a silver nanowire dispersion; then PTFE was used as a filter membrane, and AgNWs were uniformly deposited on the surface of the filter membrane by suction filtration; the filter membrane with AgNWs on the surface was cut into an electrode rectangular strip of 50x10mm; a PDMS film was prepared, and when it was semi-cured, the filter membrane with AgNWs was attached to the surface of the PDMS for pre-polymerization, and then heat curing was continued; after removal, the filter membrane was gently peeled off, and the AgNWs electrode film with flexible substrate PDMS was cut into an electrode film of 50x10mm, a 5mm-wide copper-nickel conductive tape was arranged on part of the surface of the conductive layer, and conductive silver paste was coated to fill the gaps, to prepare the electrode layer.

[0113] Steps (1), (3) and (4) refer to Example 1.

[0114] Example 8

[0115] The high-sensitivity bending sensor based on ionomer gel according to the present application was prepared according to the following process steps:

[0116] (2) Electrode layer preparation: 5g of thermoplastic polyurethane (TPU) was dissolved in 20g of N,N-dimethylformamide (DMF) to prepare a spinning solution with a mass fraction of 20%, and a TPU fiber film was prepared as a flexible substrate by electrospinning; then 0.3g of metal silver particle material was uniformly deposited on a 10x10cm TPU polymer flexible substrate by vacuum evaporation; the electrode material was cut into a rectangle of 80x10mm, a 5mm-wide copper-nickel conductive tape was arranged on part of the surface of the conductive layer, and conductive silver paste was coated to fill the gaps, to prepare the electrode layer.

[0117] Steps (1), (3) and (4) refer to Example 1.

[0118] Example 9

[0119] The high-sensitivity bending sensor based on ionomer gel according to the present application was prepared according to the following process steps:

[0120] (1) Ionomer layer preparation: 1.5 g of acrylamide (AM) and 10 mL of deionized water were mixed uniformly, then 6.26 g of Zn(TFSI)2was added and stirred for 0.5 h; then 4 mg of N,N'-methylene bisacrylamide (MBAA) and 20 mg of potassium persulfate (KPS) were added and stirred for 1 h to obtain a transparent solution; the solution was mixed uniformly and then ultrasonicated for 3 min at 20-30 °C; finally, it was injected into a self-made mold and heat cured for 9 h; after cooling, the mold was removed and cut into 40 x 15 x 2 mm ionomer strips.

[0121] Steps (2)-(4) refer to Example 1.

[0122] Example 10

[0123] The ionomer gel-based high-sensitivity bending sensor according to the present application was prepared according to the following process steps:

[0124] (1) Ionomer layer preparation: 1.5 g of acrylamide (AM) and 10 mL of deionized water were mixed uniformly, then 6.26 g of Zn(TFSI)2was added and stirred for 0.5 h; then 4 mg of N,N'-methylene bisacrylamide (MBAA) and 20 mg of potassium persulfate (KPS) were added and stirred for 1 h to obtain a transparent solution; the solution was mixed uniformly and then ultrasonicated for 3 min at 20-30 °C; finally, it was injected into a self-made mold and heat cured for 9 h; after cooling, the mold was removed and cut into 40 x 15 x 2 mm ionomer strips.

[0125] Steps (2)-(4) refer to Example 1.

[0126] Figure 2 Scanning electron microscope micrographs of the single-crosslinked PAM hydrogel and the multi-crosslinked P(SBMA-AM) hydrogel are shown. Both PAM and P(SBMA-AM) hydrogels have a honeycomb-like porous structure, and the pore size distribution of the two is 40-65 μm and 55-130 μm, respectively. The reason for the difference in pore size is analyzed: SBMA is a zwitterion, with a pair of opposite charges on the quaternary amine group and the sulfonic acid group. The molecular chain formed by copolymerization of SBMA and AM increases the concentration of cations and anions, resulting in increased interaction force between the hydrogel and water molecules, making it easier for water molecules to enter the hydrogel network, causing the internal network structure of the hydrogel to be loose. In addition, there is a strong electrostatic repulsion between the zwitterionic segments, which is also a cause of the loose network, so the multi-crosslinked P(SBMA-AM) hydrogel with larger pore size is more conducive to the transmission and migration of ions in the polymer network.

[0127] The ionomer material in Example 10 has a decrease in mechanical properties, mechanical adhesion properties, electrical properties compared to Example 1, and the device made therefrom also has a lower sensitivity. Among them, the residual strain of the ionic gel in Example 10 is 3.73%, the adhesion strength with the electrode material is 13 kPa, the ionic conductivity is 12.6 ms / cm, and the sensitivity of the device is 32 mV / 1% strain.

[0128] Example 11

[0129] The high-sensitivity bending sensor based on the ionomer gel according to the present application is prepared according to the following process steps:

[0130] (1) Preparation of ionomer layer: 1.6 g of acrylamide (AM), 0.4 g of methacrylic acid sulfobetaine (SBMA) and 10 mL of deionized water are uniformly mixed, then 6.26 g of Zn(TFSI)2 is added and stirred for 0.5 hours; then 4 mg of N,N'-methylene bisacrylamide (MBAA) and 20 mg of potassium persulfate (KPS) are added and stirred for 1 hour to obtain a transparent solution; the solution is uniformly mixed and then ultrasonicated at 20-30°C for 3 min; finally, it is injected into a self-made mold and heat cured for 9 h; after cooling, the mold is removed and cut into an ionomer strip of 40x15x2 mm.

[0131] Steps (2)-(4) refer to Example 1.

[0132] Example 12

[0133] The high-sensitivity bending sensor based on the ionomer gel according to the present application is prepared according to the following process steps:

[0134] (1) Preparation of ionomer layer: 1.6 g of acrylamide (AM), 0.4 g of methacrylic acid sulfobetaine (SBMA) and 10 mL of deionized water are uniformly mixed, then 6.26 g of Zn(TFSI)2 is added and stirred for 0.5 hours; then 4 mg of N,N'-methylene bisacrylamide (MBAA) and 20 mg of potassium persulfate (KPS) are added and stirred for 1 hour to obtain a transparent solution; the solution is uniformly mixed and then ultrasonicated at 20-30°C for 3 min; finally, it is injected into a self-made mold and heat cured for 9 h; after cooling, the mold is removed and cut into an ionomer strip of 40x15x2 mm.

[0135] Steps (2)-(4) refer to Example 1.

[0136] Example 13

[0137] The high-sensitivity bending sensor based on the ionomer gel according to the present application is prepared according to the following process steps:

[0138] Steps (1)-(3) refer to Example 1, without encapsulation. In the present application, the ionic hydrogel containing Zn(TFSI)2without encapsulation has a weight loss of 55.6% after 12 h; after encapsulation, the weight can be maintained at 95.6% after 12 h, thus the encapsulated gel can prevent water evaporation, so as to facilitate the application of the sensor in long-term use monitoring, further improving the stability and service life of the device.

[0139] Example 14

[0140] The high-sensitivity bending sensor based on ionic polymer gel according to the present application is prepared according to the following process steps:

[0141] (1) Preparation of ionic polymer layer: 1.5 g of acrylamide (AM), 0.5 g of methacrylic acid sulfobetaine (SBMA) and 10 mL of deionized water are uniformly mixed, then 6.26 g of Zn(TFSI)2is added and stirred for 0.5 h; then 4 mg of N,N'-methylene bisacrylamide (MBAA) and 20 mg of potassium persulfate (KPS) are added and stirred for 1 h to obtain a transparent solution; after uniform mixing of the solution, ultrasonic treatment is performed at 20-30°C for 3 min; finally, it is injected into a self-made mold and heat cured for 12 h; after cooling, the mold is removed and cut into 40×5×5 mm ionic polymer strips.

[0142] (2) Preparation of electrode layer: 5 g of thermoplastic polyurethane (TPU) is dissolved in 20 g of N,N-dimethylformamide (DMF) to prepare a 20% mass fraction of spinning solution, and a TPU fiber membrane is prepared as a polymer flexible substrate by electrospinning; then 0.45 g of metal silver particle material is uniformly deposited on a 10×10 cm TPU polymer flexible substrate by vacuum evaporation to obtain a TPU / Ag electrode material; the electrode material is cut into 80×5 mm rectangles, then topologically optimized to form a serpentine electrode structure for better deformation; and a copper-nickel conductive tape with a width of 5 mm is arranged on part of the surface of the conductive layer, and conductive silver paste is coated to fill the gaps.

[0143] (3) Assembly: the electrode layer is attached to the four side walls of the ionic polymer layer to prepare a strip-shaped ionic bending sensor.

[0144] (4) Encapsulation: finally, the device is encapsulated with silicone rubber and applied to sensing monitoring.

[0145] Figure 7The electrical signal output of the ion-type flexible bending sensor prepared in Example 14 when bending in the X and Y directions is shown. The Z-axis direction is the length direction of the ion gel central sensitive layer, the Y-axis direction is the thickness direction of the ion gel central sensitive layer, and the X-axis direction is the width direction of the ion gel central sensitive layer. X represents the voltage output of the X-axis electrode pair, Y+ represents the voltage output of the Y-axis electrode pair when bending in the positive direction of the Y-axis, and Y- represents the voltage output of the Y-axis electrode pair when bending in the negative direction of the Y-axis. When bending 90° in the positive direction of the Y-axis, stretching and compression on both sides of the Y-direction electrode are caused, so that the anions and cations migrate in the Y direction and accumulate on both sides of the Y direction, respectively. With the increase of the bending angle, the voltage value collected in the Y direction gradually increases, forming an upward peak; the deformation in the Y direction has little effect on the X direction, so the voltage value collected in the X direction has little obvious change. Similarly, when bending 90° in the negative direction of the Y-axis, the anions and cations migrate to different electrode sides, so that the voltage value collected gradually decreases with the increase of the bending angle, forming a downward peak; the X direction still has no obvious change. Similarly, when bending in the positive and negative directions of the X direction, similar signal peaks will be generated: the X-axis electrode pair generates upward and downward peaks when bending in the positive and negative directions of the X-axis, and the voltage output of the Y-axis electrode pair has no obvious change. The results show that the sensor has the function of two-degree-of-freedom bending recognition.

[0146] Comparative Example 1

[0147] The ion polymer gel was prepared according to the following process steps:

[0148] After uniformly mixing 0.5 g of methacrylic acid sulfobetaine (SBMA) with 10 mL of deionized water, 4 mg of N,N'-methylene bisacrylamide (MBAA) and 20 mg of potassium persulfate (KPS) were added, stirred for 1 hour to obtain a transparent solution; after uniformly mixing the solution, ultrasonic was performed at 20-30°C for 3 min; finally, it was injected into a self-made mold and heat cured for 9 h.

[0149] The pure polymethacrylic acid sulfobetaine network has poor mechanical properties and the gel is relatively soft and cannot be shaped, so it cannot be used as an ion polymer material for devices.

Claims

1. A high-sensitivity bending sensor based on ionic polymer gel, characterized by, The high-sensitivity bending sensor based on ionomer gel comprises an ion gel central sensitive layer with a double-network structure and electrode layers attached to four side walls of the strip-shaped ion gel central sensitive layer in pairs, the number of the electrode pairs is greater than or equal to 2; the electrode layers are in a serpentine shape formed by topology optimization; the ion gel central sensitive layer has a double-network structure formed by cross-linking and polymerization of zwitterionic polymer monomers and flexible polymer monomers, the double-network structure comprises an elastic polymer skeleton formed by polymerization of flexible polymer monomers and a poly-zwitterion channel formed by zwitterionic polymers; the ion precursor solution of the ion gel central sensitive layer comprises free ions and a solvent in addition to the zwitterionic polymer monomers and the flexible polymer monomers; the anions and cations of the free ions can move freely in the poly-zwitterion channel; the size of the cations of the free ions is smaller than that of the anions; the free ions are selected from one or more of zinc triflate and lithium triflate; the high-sensitivity bending sensor based on ionomer gel senses bending by the potential difference formed by the asymmetric movement of the anions and cations of the free ions caused by bending.

2. The high-sensitivity bend sensor based on ionomer gel according to claim 1, characterized in that, The zwitterionic polymer monomers are methacrylic acid sulfobetaine, and the flexible polymer monomers are acrylamide.

3. The high-sensitivity bend sensor based on ionomer gel according to claim 1, wherein, The size difference between the anions and cations of the free ions is between 0.1 nm and 0.8 nm.

4. The high-sensitivity bend sensor based on ionomer gel according to claim 1, wherein, The solvent is selected from at least one of water, an organic solvent, and a deep eutectic solvent.

5. The high-sensitivity bend sensor based on ionomer gel according to claim 1, wherein, The electrode layer comprises a flexible substrate and a conductive material coated on the surface of the flexible substrate; the conductive material is selected from one or more of a metal film with a specific microstructure, metal particles, carbon nanotubes, metal nanowires, graphene, MXene, and a conductive polymer.

6. The high-sensitivity bend sensor based on ionomer gel according to claim 5, wherein, The conductive material is deposited on the surface of the flexible substrate to obtain the electrode layer.

7. The method of preparing a high-sensitivity bending sensor based on an ionomer gel according to any one of claims 1 to 6, characterized in that, The preparation method comprises: forming and curing the ion precursor solution of the ion gel central sensitive layer to obtain the ion gel central sensitive layer; and attaching the electrode layers in pairs to the surface of the ion gel central sensitive layer to obtain the high-sensitivity bending sensor based on ionomer gel.

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