An ion-type pressure sensor with high sensitivity and low drift achieved through a bulk capacitance strategy, and its preparation method and application

Abstract

The present invention provides an ionization pressure sensor that achieves high sensitivity and low drift through a body capacitance strategy, as well as a preparation method and application thereof. First, the present invention provides a preparation method of an ionization composite material based on epoxy groups, specifically, uniformly dispersing material A, material B and material C in a solvent; curing after evaporating the solvent; wherein, material A is an ionic liquid with epoxy groups, including epoxy ionic liquid 1 and / or epoxy ionic liquid 2; material B includes an organic polyamine compound or a polyetheramine; material C is a conductive filler, and further, the prepared ionization composite material is used as a sensor material layer to obtain an ionization pressure sensor that can simultaneously take into account high sensitivity and low drift. The present invention solves the contradiction between the high sensitivity and low drift of the current ionization pressure sensor, and the obtained high-sensitivity, low-drift ionization pressure sensor has broad application prospects in technical fields such as human-computer interaction and wearable medical devices.

Description

Technical Field

[0001] The present invention belongs to the field of sensor technology, and particularly relates to an ionization pressure sensor that achieves high sensitivity and low drift through a body capacitance strategy, as well as a preparation method and application thereof. Background Art

[0002] In recent years, with the increasing portability of health monitoring devices and the diversification of sensor applications, flexible pressure sensors have gained widespread application as a key information acquisition device. They possess properties similar to those of human skin. By covering any surface with force information, they can sense the properties of the target object and convert the received information into electrical or other output signals according to specific patterns, providing a strong foundation for the development of the Internet of Things. Compared to traditional rigid sensors, flexible pressure sensors offer greater advantages when applied to complex curved surfaces due to their excellent ductility and flexibility. This breakthrough from rigidity to flexibility has greatly expanded the application scenarios of sensors.

[0003] Flexible capacitive pressure sensors have attracted widespread attention in the field of high-performance sensing technology due to their high drift stability and simple structure. However, these sensors exhibit low sensitivity over a wide pressure range or under high pressure conditions and are prone to saturation, which severely limits their potential for application in extreme environments. In order to address the problems of low sensor sensitivity and low signal-to-noise ratio, a new type of "ion-electrode" flexible pressure sensor has emerged in recent years. By forming a double layer when the electrode and the ion conductor are in contact, a larger unit area capacitance is generated at the interface, which increases the sensitivity of the ion-electrode pressure sensor by several orders of magnitude compared to traditional capacitive pressure sensors. In addition, due to its low preparation cost, simple process, and flexible deformation, it has also been widely used in emerging fields such as health monitoring, wearable electronic devices, human-computer interaction, virtual reality, and soft robotics.

[0004] Existing ion-type flexible pressure sensors are mainly divided into the following two categories: the first is an ion gel-based flexible pressure sensor; the other is a polyion elastomer-based flexible pressure sensor. Both have demonstrated excellent sensing performance in different application scenarios, but both have obvious shortcomings.

[0005] For ion gel-based flexible pressure sensors, ion gels are materials composed of a polymer network and electrolyte ions. Their conductivity varies with ion concentration and distribution. When pressure is applied, the structure and ion distribution of the ion gel change, affecting its capacitance. The sensor then measures these electrical changes to determine the applied pressure. Ion gel-based ion gel pressure sensors often have better device sensitivity and signal-to-noise ratio, especially when detecting very small pressures, where signal changes are more pronounced. Furthermore, since there are no chemical bonds between the ionic material and the polymer network, the ion migration speed within the polymer matrix also contributes to their high sensitivity. However, ion gels typically contain a large amount of liquid electrolyte. Their structure is relatively loose, and the electrolyte ions exist in a liquid state. Prolonged load increases ion migration and material fluidity, leading to significant material creep. Ion gel creep can cause geometric changes in the sensing material, such as thickness changes and dimensional deformation. This geometric change directly affects the sensor's capacitance measurement principle, resulting in signal drift and inability to accurately provide pressure feedback, significantly reducing its practical application value. In addition, ion gel materials may cause leakage of ionic liquid under high pressure conditions, which will not only cause sensor failure or affect the surrounding environment, but also cause certain biocompatibility problems.

[0006] Regarding polyion elastomer-based flexible pressure sensors: Polyion elastomers are a class of polymer materials in which one or both of anions and cations are fixed to the molecular chains. Because some or all of the ions are fixed to the molecular chains, these materials typically exhibit low electrical conductivity at low temperatures. This can also restrict ion mobility, resulting in a slow electrical response and significantly reduced device sensitivity. However, polyion elastomers generally exhibit less creep than ion gels. This is because polyion elastomers are composed of an elastic polymer network and ion-conducting components. Their structure typically includes a highly cross-linked polymer network, which provides excellent mechanical strength and elasticity, resulting in minimal deformation under long-term loads. Furthermore, the immobilization of ions to the molecular chains restricts their migration, reducing the free mobility within the material and, consequently, the creep of the functional material. This also enables the drift-free nature of ion-based flexible pressure sensors. This network structure firmly locks the ions to the polymer chains, forming a stable solid-state structure with restricted ion mobility. This solid-state structure is less susceptible to migration or leakage under external forces than ion gels containing large amounts of liquid electrolytes. Therefore, it can accurately feedback pressure information and is widely used in technical fields that require precise measurement, such as human-computer interaction and wearable medical devices.

[0007] Both types of ionized flexible pressure sensors have certain advantages and disadvantages. Ion gel-based ionized pressure sensors have the characteristics of high sensitivity and high signal-to-noise ratio, but are prone to problems such as sensor signal drift and ion leakage, resulting in inaccurate sensor signals and cannot be used for long-term static pressure measurement. Polyion elastomer-based ionized pressure sensors have the characteristics of no leakage and low creep, which makes ionized pressure sensors have the characteristics of no signal drift and can be used for long-term stable and accurate feedback of pressure information. However, sensors based on this type are often less sensitive, with low sensitivity and resolution, resulting in low detection accuracy, and are not suitable for applications requiring high precision and high sensitivity, such as biomedical sensing, precision manufacturing, and scientific research.

[0008] Therefore, how to simultaneously achieve high sensitivity and low drift of ionization pressure sensors has become a top priority in research in this field and is also a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0009] The object of the present invention is to provide a method for preparing an ionizing composite material based on epoxy groups, comprising the following steps: uniformly dispersing material A, material B and material C in a solvent; volatilizing the solvent from the obtained dispersion, and then curing to obtain the ionizing composite material based on epoxy groups; wherein material A is an ionic liquid having epoxy groups, including epoxy ionic liquid 1 and / or epoxy ionic liquid 2; material B includes an organic polyamine compound or polyetheramine; and material C is a conductive filler.

[0010] In a preferred embodiment, the material B includes tris(2-aminoethyl)amine and / or 2,2'-(ethylenedioxy)bis(ethylamine), and the material C includes carbon nanotubes and / or carboxyl-modified carbon nanotubes.

[0011] In a preferred embodiment, the molar ratio of material A to material B is 2:(0.5-2), and the material C is 2%-5% of the mass of material A; preferably, the molar ratio of material A to material B is 2:1, and the material C is 3%-4% of the mass of material A.

[0012] In a preferred embodiment, the solvent is an organic solvent; preferably, the organic solvent includes acetone; more preferably, the amount ratio of the material A to the solvent is 3 mmol: (10-200) g; most preferably, the amount ratio of the material A to the solvent is 3 mmol: (20-100) g.

[0013] In a preferred embodiment, in order to improve the dispersion effect of material A, material B and material C in the solvent, ultrasonic dispersion can be used for 1-2 hours.

[0014] In a preferred embodiment, the curing includes light curing or heat curing; preferably, the heat curing temperature is 70-80° C., and the heat curing time is 1-2 hours.

[0015] In a preferred embodiment, the epoxy ionic liquid 1 is prepared by the following method:

[0016] S1: Imidazole, sodium bicarbonate, and 4-bromo-1-butene are dissolved in acetonitrile and heated to reflux. After the reaction is completed, the mixture is filtered and rotary evaporated to obtain a crude product. The crude product is purified with dichloromethane and an extractant. A concentrated LiTFSI solution is added dropwise to the purified product until no oily precipitate is produced. The upper aqueous phase is aspirated, impurities are extracted with deionized water, and residual water is removed. The reaction pathway of step S1 in preparing epoxy ionic liquid 1 is shown in Formula I.

[0017]

[0018] S2: The reaction product of step S1 and m-chloroperbenzoic acid are dissolved in acetonitrile, reacted at room temperature for a period of time, filtered, and rotary evaporated to obtain a crude product; the crude product is purified with diethyl ether to obtain epoxy ionic liquid 1; the reaction path of step S2 in preparing epoxy ionic liquid 1 is shown in Formula II.

[0019]

[0020] Further preferably, in step S1, the molar ratio of the imidazole, sodium bicarbonate, and 4-bromo-1-butene is 1:(0.8-1.2):(1.7-2.55); preferably, the molar ratio of the imidazole, sodium bicarbonate, and 4-bromo-1-butene is 1:1:2.13.

[0021] Further preferably, in step S1, the molar volume ratio of imidazole to acetonitrile is 1 mmol:(0.5-0.75) ml; preferably, the molar volume ratio of imidazole to acetonitrile is 1 mmol:0.625 ml.

[0022] Further preferably, in step S1, the heating reflux temperature is 70-80°C, and the heating reflux time is 12-36 hours; preferably, the heating reflux temperature is 75°C, and the heating reflux time is 24 hours.

[0023] Further preferably, in step S1, the purification of the crude product comprises the following steps: dissolving the crude product with dichloromethane, drying, filtering, and rotary evaporating to remove dichloromethane; then dissolving with deionized water, and extracting with ethyl acetate, n-hexane, and diethyl ether to remove impurities. Preferably, the purpose of the drying method is to remove moisture, and conventional methods known to those skilled in the art, such as adding anhydrous magnesium sulfate, can be used. More preferably, the method for extracting impurities can be a conventional method known to those skilled in the art. Most preferably, the number of extractions with ethyl acetate is 1-3 times, the number of extractions with n-hexane is 1-2 times, and the number of extractions with diethyl ether is 1-2 times.

[0024] Further preferably, in step S1, the LiTFSI concentrated solution includes a saturated solution of LiTFSI or a solution with a mass fraction of 50%.

[0025] Further preferably, in step S1, the extraction times with deionized water are 1-5 times, and the method for removing residual water can adopt conventional methods known to those skilled in the art, such as vacuum freeze-drying for 6-12 hours.

[0026] Further preferably, in step S2, the molar ratio of the reaction product of step S1 to meta-chloroperbenzoic acid is 1:(3.2-4.8); preferably, the molar ratio of the reaction product of step S1 to meta-chloroperbenzoic acid is 1:4.

[0027] Further preferably, in step S2, the ratio of the reaction product of step S1 to acetonitrile is 1 mmol:(1.25-1.88) g; the ratio of the reaction product of step S1 to acetonitrile is 1 mmol:1.56 g.

[0028] Further preferably, in step S2, the room temperature reaction time is 24-48 hours; preferably, the room temperature reaction time is 36 hours.

[0029] Further preferably, in step S2, the purification of the crude product comprises the following steps: dissolving the crude product with diethyl ether, extracting impurities with diethyl ether after oily precipitation, and then vacuuming the purified product to remove residual diethyl ether. Preferably, the ethyl acetate extraction is performed 1-4 times.

[0030] In a preferred embodiment, the epoxy ionic liquid 2 is prepared by the following method:

[0031] Imidazole, sodium carbonate, epichlorohydrin, and a concentrated solution of LiTFSI were dissolved in acetonitrile and heated to reflux. After the reaction was complete, the mixture was filtered and rotary evaporated to obtain a crude product. The crude product was purified with deionized water to obtain epoxy ionic liquid 2. The reaction pathway for preparing epoxy ionic liquid 2 is shown in Formula III.

[0032]

[0033] Further preferably, the amount ratio of the imidazole, sodium carbonate, epichlorohydrin and LiTFSI concentrated solution is 1 mmol: (1.6-2.4) mmol: (1.6-2.4) mmol: (0.23-0.34) g; preferably, the amount ratio of the imidazole, sodium carbonate, epichlorohydrin and LiTFSI is 1 mmol: 2 mmol: 2 mmol: 0.29 g.

[0034] Further preferably, the LiTFSI concentrated solution includes a saturated solution of LiTFSI or a solution with a mass fraction of 50%.

[0035] Further preferably, the usage ratio of imidazole to acetonitrile is 1 mmol:(0.8-1.2) g; preferably, the usage ratio of imidazole to acetonitrile is 1 mmol:1 g.

[0036] More preferably, the heating reflux temperature is 70-80° C., and the heating reflux time is 12-36 h; preferably, the heating reflux temperature is 75° C., and the heating reflux time is 24 h.

[0037] Further preferably, the crude product is purified by extracting impurities with deionized water and then removing residual water by vacuum freeze-drying. Preferably, the deionized water extraction is performed 1-10 times and the vacuum freeze-drying time is 6-12 hours.

[0038] Another object of the present invention is to provide an ionizing composite material based on epoxy groups prepared by any of the above methods.

[0039] Another object of the present invention is to provide a highly sensitive, low-drift ionization pressure sensor, comprising a sensor material layer, an electrode layer and a packaging layer, wherein the sensor material layer comprises an ionization composite material based on epoxy groups prepared by any of the above methods, the packaging layer comprises a PDMS film, and the electrode layer comprises a PI / Cu composite film.

[0040] Another object of the present invention is to provide a method for preparing a highly sensitive, low-drift ionization pressure sensor, which specifically includes aligning and packaging an upper packaging layer, an upper electrode layer, a sensing material layer, a lower electrode layer and a lower packaging layer from top to bottom.

[0041] Another object of the present invention is to provide a high-sensitivity, low-drift ionization pressure sensor for use in the fields of human-computer interaction and wearable medical devices.

[0042] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0043] The present invention provides an ionized composite material based on epoxy groups and a preparation method thereof, which is then used as a sensor material layer to realize a general method of a high-sensitivity, low-drift ionized pressure sensor through a body capacitance strategy. In the present invention, first, a polyion elastomer is selected as the functional material body to effectively reduce creep and greatly reduce signal drift. Secondly, the conductivity and sensitivity of the sensor are improved by adding conductive fillers to the polyion elastomer. A synergistic effect occurs between the conductive filler and the ions in the polyion elastomer, greatly improving the conductivity. Not only that, the ions conducted in the polymer and the electrons conducted in the filler form many tiny capacitors. These capacitors can be connected in series or in parallel, which will further improve the sensitivity of the capacitive sensor. The specific principle is as follows. Figure 1 Finally, by using the prepared composite material of polyionic elastomer and conductive filler as the sensing material layer, a highly sensitive, low-drift ionotropic pressure sensor can be assembled. The resulting sensor has broad application prospects in human-computer interaction, wearable medical devices, and other technological fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] These and / or other aspects and advantages of the present invention will become more apparent and more readily understood from the following detailed description of embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0045] Figure 1 This is a schematic diagram of the body capacitance sensing principle provided by the present invention;

[0046] Figure 2 is the electrical conductivity of the ionized composite material of Example 3 of the present invention;

[0047] Figure 3 is the electrical conductivity of the ionized composite material of Example 4 of the present invention;

[0048] Figure 4 is the electrical conductivity of the ionized composite material of Example 5 of the present invention;

[0049] Figure 5 The electrical conductivity of the polyion elastomer without conductive filler in Comparative Example 1 of the present invention;

[0050] Figure 6 This is the sensitivity curve of the ionizing composite material of Example 3 of the present invention;

[0051] Figure 7 This is the sensitivity curve of the ionizing composite material of Example 4 of the present invention;

[0052] Figure 8 This is the sensitivity curve of the ionizing composite material of Example 5 of the present invention;

[0053] Figure 9 This is the sensitivity curve of the ionizing composite material of Comparative Example 1 of the present invention;

[0054] Figure 10 It is the sensitivity comparison curve of the experimental group and the control group of the present invention;

[0055] Figure 11 This is the signal drift curve of the ionized composite material of Example 3 of the present invention;

[0056] Figure 12 This is the signal drift curve of the ionized composite material of Example 4 of the present invention;

[0057] Figure 13 This is the signal drift curve of the ionized composite material of Example 5 of the present invention;

[0058] Figure 14 This is the signal drift curve of the ionizing composite material of Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0059] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. However, it should be understood that the protection scope of the present invention is not limited to the specific embodiments.

[0060] Unless otherwise specified, the technical means used in the present invention are conventional means well known to those skilled in the art. The various raw materials, reagents, instruments, and equipment used in the present invention can be purchased from the market or prepared by existing methods. Unless otherwise specified, the reagents used in the present invention are of analytical grade.

[0061] Example 1

[0062] Synthesis of epoxy ionic liquid 1:

[0063] Preparation: Dissolve imidazole (80 mmol, 5.5 g), sodium bicarbonate (80 mmol, 6.76 g), and 4-bromo-1-butene (170 mmol, 23.65 g) in 50 mL of acetonitrile, heat at 75°C, and reflux for 24 h. After the reaction is complete, cool, filter, and rotary evaporate to obtain the crude product.

[0064] Purification: Dissolve the crude product in dichloromethane, dry with anhydrous magnesium sulfate, filter, and remove dichloromethane by rotary evaporation. Dissolve the product in deionized water and extract impurities three times with ethyl acetate, once with n-hexane, and once with ether.

[0065] Ion replacement: LiTFSI concentrated solution was added dropwise until no oily precipitate was produced, the upper aqueous phase was aspirated, impurities were extracted with deionized water 5 times, and then the residual water was removed by vacuum freeze-drying for 12 hours.

[0066] Functionalization: Dissolve the product from the previous step (8 mmol, 3.659 g) and m-chloroperbenzoic acid (32 mmol, 6.496 g) in 12.5 g of acetonitrile and react at room temperature for 36 hours. Filter and evaporate to obtain a crude product.

[0067] Purification: The crude product was dissolved in diethyl ether to produce an oily precipitate. The impurities were extracted with diethyl ether four times, and the remaining diethyl ether was removed by vacuum extraction to complete the preparation of epoxy ionic liquid 1.

[0068] Example 2

[0069] Synthesis of epoxy ionic liquid 2:

[0070] Preparation: Dissolve imidazole (20 mmol, 1.36 g), sodium carbonate (40 mmol, 2.88 g), epichlorohydrin (40 mmol, 3.7 g), and LiTFSI (5.74 g) in 20 g of acetonitrile, heat to 75°C, and reflux for 24 h. After the reaction is complete, cool, filter, and rotary evaporate to obtain the crude product.

[0071] Purification: After extracting impurities with deionized water 10 times, the remaining water was removed by vacuum freeze-drying for 12 hours to complete the preparation of epoxy ionic liquid 2.

[0072] Example 3

[0073] Synthesis of ionomeric composites containing conductive fillers:

[0074] 6 mmol of the epoxy ionic liquid 1 prepared in Example 1, 3 mmol of 2,2'-(ethylenedioxy)bis(ethylamine), and 0.1285 g of a carboxyl-modified carbon nanotube (4% of the monomer mass) conductive filler were ultrasonically dispersed in 50 g of acetone solvent for 2 hours to obtain a dispersion. Subsequently, the dispersion was dropped onto a glass plate to evaporate the solvent. After the solvent evaporated, it was placed on a hot plate at 80 degrees Celsius for curing. After curing for two hours, a composite ionized material of a polyionic elastomer and carboxyl carbon nanotubes was obtained. Its synthesis path is shown in Formula IV.

[0075]

[0076] Example 4

[0077] Synthesis of ionomeric composites containing conductive fillers:

[0078] 6 mmol of the epoxy ionic liquid 2, 3 mmol of polyetheramine D-2000, and 0.3575 g of a carboxyl-modified carbon nanotube (3% of the monomer mass) conductive filler prepared in Example 2 were ultrasonically dispersed in 200 g of acetone solvent for 2 hours to obtain a dispersion. Subsequently, the dispersion was dropped onto a glass plate to evaporate the solvent. After the solvent evaporated, the dispersion was placed on a hot plate at 80 degrees Celsius for curing. After curing for two hours, a composite ionized material of a polyionic elastomer and carboxyl carbon nanotubes was obtained. The synthesis path is shown in Formula V.

[0079]

[0080] Example 5

[0081] Synthesis of ionomeric composites containing conductive fillers:

[0082] 6 mmol of the epoxy ionic liquid 2 prepared in Example 2, 3 mmol of tris(2-aminoethyl)amine, and 0.1013 g of carbon nanotubes (3% of the monomer mass) as a conductive filler were ultrasonically dispersed in 40 g of acetone solvent for 2 hours to obtain a dispersion. Subsequently, the dispersion was dropped onto a glass plate to evaporate the solvent. After the solvent evaporated, the dispersion was placed on a hot plate at 80 degrees Celsius for curing. After curing for two hours, a composite ionomer material of polyionic elastomer and carbon nanotubes was obtained. The synthesis path is shown in Formula VI.

[0083]

[0084] Comparative Example 1

[0085] Synthesis of polyion elastomers without conductive fillers:

[0086] 4 mmol of the epoxy ionic liquid 1 prepared in Example 1 was mixed with 2 mmol of 2,2′-(ethylenedioxy)bis(ethylamine), shaken for 5 minutes, poured onto a glass plate, and cured at 80 degrees Celsius for two hours to obtain a polyionic elastomer. The synthesis route is shown in Formula VII.

[0087]

[0088] Effect Example 1

[0089] The ionized composite materials containing conductive fillers prepared in Examples 3-5 (experimental group) and the polyionic elastomer without conductive fillers prepared in Comparative Example 1 (control group) were tested using a broadband dielectric impedance spectrometer at 10 0 ~10 6 Changes in conductivity at Hz frequencies.

[0090] Results and Discussion: The test results show that in 10 3The conductivity of Comparative Example 1 under the test conditions of Hz alternating current is about 1.84×10 -7 S / cm, while the conductivity of the ionized composite materials of Examples 3-5 were 1.05×10 -4 S / cm, 1.70×10 -6 S / cm and 1.175×10 -4 S / cm. It can be seen that the conductivity of the material in the experimental group using the bulk capacitance strategy increased by 1-3 orders of magnitude compared to the control group, which further reflects the significant effect of the bulk capacitance effect on improving conductivity, making it possible to prepare highly sensitive sensors. Specific data are shown in the attached Figure 2-5 shown.

[0091] Effect Example 2

[0092] The ionized composite materials containing conductive fillers prepared in Examples 3-5 (experimental groups 1-3, respectively) and the polyion elastomer without conductive fillers prepared in Comparative Example 1 (control group 1) were used as sensing material layers of sensors to prepare sensors for sensitivity testing and signal drift testing.

[0093] The sensor fabrication method specifically includes aligning and encapsulating an upper encapsulation layer, an upper electrode layer, a sensing material layer, a lower electrode layer, and a lower encapsulation layer in order from top to bottom. The encapsulation layer is a PDMS film; the electrode layer is a PI / Cu composite film; and the sensing material layer is the material prepared in Examples 3-5 and Comparative Example 1.

[0094] Results and Discussion

[0095] (1) Sensitivity is a physical quantity that characterizes the sensitivity of a pressure sensor to external pressure, and is the change in output caused by a pressure range of kilopascals. High sensitivity is very important for flexible pressure sensors because it can detect extremely small pressure changes, ensuring that the sensor can still provide accurate and reliable measurements in complex and changing environments. For capacitive flexible pressure sensors, sensitivity is defined as the change in capacitance signal relative to the initial capacitance value under unit pressure, that is, S = δ(ΔC / C0) / δP, where S represents sensitivity (kPa –1 ), P represents pressure (kPa), C represents capacitance under load (pF), and C0 represents the initial capacitance value when no load is applied. We used a compression fatigue testing machine to test the sensitivity of flexible pressure sensors fabricated using a control group of polyionomers and an experimental group of ionized composite materials. We recorded the variation of the sensor's capacitance signal with pressure. After data processing, we obtained a curve with pressure as the horizontal axis and capacitance change rate as the vertical axis. The slope of the curve represents the device's sensitivity.

[0096] The data results show that the pressure sensor prepared based on the polyionic elastomer control group (Comparative Example 1) has a lower device sensitivity of only 0.44 kPa. –1 , while the sensors prepared from the ionized composite materials of Examples 3-5 have a resistance of 15 kPa –1 , 6.5kPa –1 and 3382kPa –1 The sensitivity of the prepared sensor is 1-3 orders of magnitude higher than that of the traditional polyion elastomer. Figure 6-10 shown.

[0097] (2) Signal drift is a common phenomenon in flexible pressure sensors, especially under high-pressure working conditions. When the pressure on the sensor is close to the modulus, the signal drift phenomenon is more obvious. This makes it impossible for flexible pressure sensors to achieve accurate feedback of pressure, reducing their practical application value. Therefore, sensors based on ionized composite materials as functional materials need to have not only high device sensitivity, but also no signal drift under constant pressure conditions, and accurate feedback of pressure information, so that the sensor can have both sensitive and accurate characteristics.

[0098] The prepared flexible pressure sensors were tested for pressure signal drift, that is, a fixed pressure value was applied to the sensor, and the long-term change in the capacitance signal was observed. The test results show that although the pressure sensor prepared based on the polyion elastomer control group has a relatively low sensitivity, the low creep and no-leakage characteristics of the polyion elastomer material also enable it to perform long-term stable and accurate measurements under high pressure conditions, with basically no signal drift. On this basis, the performance of traditional polyion elastomers is optimized through the volume capacitance strategy. While ensuring the low creep and no-leakage characteristics of the polyion elastomer material, the prepared sensor has a relatively high sensitivity while ensuring no signal drift through the addition of conductive fillers and the formation of volume capacitance. The specific signal drift test data is shown in the attached figure. Figure 11-14 shown.

[0099] This patent further demonstrates the advantages of bulk capacitance, both from the technical principle and experimental data. By leveraging the intrinsic properties of the material, this patent addresses the existing conflict between high sensitivity and low drift in ionized pressure sensors. Using the resulting epoxy-based ionized composite material as the sensor material layer, a highly sensitive and low-drift ionized pressure sensor can be fabricated, promising applications in human-computer interaction, wearable medical devices, and other technological fields.

[0100] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for preparing an ionizing composite material based on epoxy groups, characterized in that: The following steps are involved: Dispersing material A, material B, and material C uniformly in a solvent; evaporating the solvent from the resulting dispersion, and curing the dispersion to obtain an epoxy-based ionized composite material; wherein material A is an ionic liquid having epoxy groups, including epoxy-based ionic liquid 1 and / or epoxy-based ionic liquid 2; material B includes an organic polyamine compound or a polyetheramine; and material C includes carbon nanotubes and / or carboxyl-modified carbon nanotubes; The epoxy ionic liquid 1 is prepared by the following method: S1: Imidazole, sodium bicarbonate, and 4-bromo-1-butene are dissolved in acetonitrile and heated to reflux. After the reaction is complete, the mixture is filtered and rotary evaporated to obtain a crude product. The crude product is purified with dichloromethane and an extractant. A concentrated LiTFSI solution is added dropwise to the purified product until no oily precipitate is produced. The upper aqueous phase is aspirated, impurities are extracted with deionized water, and residual moisture is removed. S2: dissolving the reaction product of step S1 and m-chloroperbenzoic acid in acetonitrile, reacting at room temperature for a period of time, filtering, and rotary evaporating to obtain a crude product; purifying the crude product with ether to obtain epoxy ionic liquid 1; The epoxy ionic liquid 2 is prepared by the following method: Imidazole, sodium carbonate, epichlorohydrin and LiTFSI concentrated solution were dissolved in acetonitrile and heated to reflux. After the reaction was completed, the crude product was filtered and rotary evaporated to obtain the crude product. The crude product was purified with deionized water to obtain epoxy ionic liquid 2.

2. The method for preparing an ionized composite material based on epoxy groups as claimed in claim 1, wherein: The material B includes tris(2-aminoethyl)amine and / or 2,2'-(ethylenedioxy)bis(ethylamine), The molar ratio of the material A to the material B is 2:(0.5-2), and the material C accounts for 2%-5% of the mass of the material A.

3. The method for preparing an ionized composite material based on epoxy groups as claimed in claim 1, wherein: In step S1, the molar ratio of imidazole, sodium bicarbonate, and 4-bromo-1-butene is 1:(0.8-1.2):(1.7-2.55).

4. The method for preparing an ionizing composite material based on epoxy groups as claimed in claim 1, wherein: In step S2, the molar ratio of the reaction product of step S1 to m-chloroperbenzoic acid is 1:(3.2-4.8).

5. The method for preparing an ionizing composite material based on epoxy groups as claimed in claim 1, wherein: The usage ratio of the imidazole, sodium carbonate, epichlorohydrin and LiTFSI concentrated solution is 1 mmol: (1.6-2.4) mmol: (1.6-2.4) mmol: (0.23-0.34) g.

6. An ionizing composite material based on epoxy groups prepared by the method according to any one of claims 1 to 5.

7. A high-sensitivity, low-drift ionization pressure sensor, characterized in that: It comprises a sensor material layer, an electrode layer and a packaging layer, wherein the sensor material layer comprises the epoxy group-based ionization composite material according to claim 6, the packaging layer comprises a PDMS film, and the electrode layer comprises a PI / Cu composite film.

8. Application of the highly sensitive, low-drift ionization pressure sensor according to claim 7 in the fields of human-computer interaction and wearable medical devices.

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