Method for preparing ion electronic sensor based on entangled polymer network

Abstract

The invention belongs to the technical field of tactile sensors, and discloses a method for preparing an ion electronic sensor based on an entangled polymer network, and the method comprises the following steps: S1, preparing an initial polymer; s2, preparation of a prepolymer solution; s3, preparation of intermediate layer gel of the sensor; s4, preparing a sensor electrode; the preparation method has the following beneficial effects: 1, by preparing the prepolymer solution with specific crosslinking density and initial polymer concentration, the middle layer gel of the sensor has the characteristics of high elasticity and low viscosity, and micron-level pores with uniform size are macroscopically formed, so that the energy dissipation is low under the stimulation of external force, and the sensitivity is high; and after deformation, the device has rapid recovery capability and is suitable for high-frequency detection. 2, an inter-chain highly physical entangled network is formed, the water content in the middle layer gel of the sensor is reduced, the water loss rate of the gel in a room temperature environment is reduced, and the cycle response frequency of the sensor is increased;

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tactile sensor, in particular to a method for preparing an ionic electronic sensor based on entangled polymer network. BACKGROUND

[0002] Ionic electronic flexible force sensors are a kind of widely studied sensor devices, among which ionic piezoelectric and ionic triboelectric devices can directly detect dynamic displacement and force without external power supply, and have wide application prospects in wearable health, human-computer interaction and environmental monitoring fields. However, these devices have three key limitations in dynamic stimulus response: 1. Viscoelastic dissipation: the mechanical energy loss is caused by the relaxation lag of molecular chain segments when the polymer matrix is deformed at high frequency; 2. Ionic migration delay: the carrier transport rate is limited by the distribution of polymer free volume, which is difficult to match the high-frequency electric field change; 3. In the contact-separation cycle, the friction and adhesion effect of the electrode / dielectric interface will introduce additional energy dissipation. This intrinsic force-electric coupling dynamics mismatch limits the cutoff frequency to below 100 Hz.

[0003] In order to improve the response speed, common strategies include designing microstructured dielectric layers and reducing polymer content, although the bulk viscoelasticity is reduced by introducing microstructures, and the lower polymer content promotes the flow of ions in the pores of the hydrogel matrix, but the response time is still mostly in the order of hundreds of milliseconds, which cannot meet the detection of higher frequency. For acoustic sensing or high-frequency vibration monitoring applications, the high-frequency detection capability of the sensor under slight vibration is very important. SUMMARY

[0004] To solve the above problems, the present application provides a method for preparing an ionic electronic sensor based on an entangled polymer network, which is realized by the following technical scheme.

[0005] The method for preparing an ionic electronic sensor based on an entangled polymer network comprises the following steps: S1, preparation of an initial polymer, dissolving an acrylamide monomer in deionized water, adjusting the molar ratio of deionized water to acrylamide monomer, and preparing an initial polymer with different concentrations; S2, preparation of a prepolymer solution, adding a crosslinking agent and an initiator to the initial polymer with different concentrations, for each concentration of the initial polymer, adjusting the molar ratio of the crosslinking agent to the acrylamide monomer, then adjusting the molar amount of the initiator, so that the molar ratio of the crosslinking agent to the initiator remains unchanged, stirring and then ultrasonic treatment, to prepare a prepolymer solution with different crosslinking densities; S3, preparation of sensor intermediate layer gel, the prepolymer solution is injected into a polytetrafluoroethylene mold through a dropper, and then the polytetrafluoroethylene mold is placed under a UV lamp for irradiation to complete a polymerization reaction, the polytetrafluoroethylene mold has a conical cavity, so that the sensor intermediate gel after molding has a conical protrusion, and the sensor intermediate gel after molding is demolded and soaked in deionized water for spontaneous swelling; S4, preparation of a sensor electrode, a gold conductive film is sputtered on the surface of a PET substrate by a metal sputtering instrument to form a flexible electrode, the flexible electrode is cut by a CO2 laser cutting machine, a copper lead is led out at one end of the cut flexible electrode, and the gold conductive film is connected to the copper lead through conductive silver paste, and the flexible electrode is packaged using PI tape after the conductive silver paste is solidified. S5, preparation of a sensor, the sensor intermediate gel is used as an intermediate layer of the sensor, and the upper and lower sides of the sensor intermediate gel are PET / Au composite flexible electrodes, the lower flexible electrode is in contact with the side of the sensor intermediate gel away from the conical protrusion and is fixed, and the upper flexible electrode is in a critical contact state with the sensor intermediate gel and is fixed.

[0006] As a further scheme of the present application, in step S1, the molar ratio of deionized water to acrylamide monomer is 2, 4, 8 and 12 respectively.

[0007] As a further scheme of the present application, in step S2, the molar ratio of crosslinking agent to acrylamide monomer is 3.2×10 -7 , 3.2×10 -5 , 3.2×10 -3 and 3.2×10 -2 ; and the molar ratio of crosslinking agent to initiator is 0.4.

[0008] As a further scheme of the present application, in step S2, the crosslinking agent is N,N'-methylene bisacrylamide; and the initiator is 2,2-dimethoxy-2-phenylphenylacetophenone.

[0009] As a further scheme of the present application, the thickness of the polytetrafluoroethylene mold is 2 mm, the number of the conical cavities is 9×9, the bottom diameter of the conical cavities is 0.5 mm, and the height of the conical cavities is 0.5 mm.

[0010] As a further scheme of the present application, in step S3, the wavelength of the ultraviolet light emitted by the ultraviolet lamp is 365 nm, the irradiation time is 4 h, and the spontaneous swelling time in deionized water is 24 h.

[0011] As a further scheme of the present application, in step S4, the thickness of the gold conductive film is 35 nm, and the size of the flexible electrode after cutting is 15 mm×15 mm.

[0012] The beneficial effects of this invention are as follows: 1. By preparing a prepolymer solution with a specific crosslinking density and initial polymer concentration, the sensor intermediate layer gel with high entanglement and low crosslinking has high elasticity and low viscosity based on interchain physical entanglement and appropriate chemical crosslinking. It also forms micron-sized pores with uniform size on a macroscopic scale, which makes it have low energy dissipation under external force stimulation and rapid recovery ability after deformation, making it suitable for high frequency detection.

[0013] 2. By preparing a prepolymer solution with a specific crosslinking density and a high initial polymer concentration, a highly physically entangled network between chains is formed. The water content inside the sensor interlayer gel is reduced compared to low crosslinking and low entanglement gels, which reduces the water loss rate of the sensor interlayer gel at room temperature and significantly improves the number of sensor cycle responses. Attached Figure Description

[0014] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 Schematic diagram of the structure of an ion electron sensor; Figure 2 Schematic diagram of the structure of the gel in the middle layer of the sensor; Figure 3 Schematic diagram of the viscoelastic gel mechanical structure of the sensor's intermediate layer gel at different crosslinking densities and polymer concentrations; Figure 4 Schematic diagram of the interchain structure of the sensor's intermediate layer gel at different crosslinking densities and polymer concentrations; Figure 5 Pore ​​structure diagram of the sensor's intermediate layer gel at different crosslinking densities; Figure 6 Pore ​​structure diagram of the sensor's intermediate layer gel at different polymer concentrations; Figure 7 Schematic diagram of viscoelasticity detection of the sensor's intermediate layer gel at different crosslinking densities; Figure 8 Schematic diagram of viscoelasticity detection of the sensor's intermediate layer gel at different polymer concentrations; Figure 9 Schematic diagram of the frequency response achievable by sensor interlayer gels formed with different crosslinking densities; Figure 10 Schematic diagram of the frequency response achievable by sensor interlayer gels formed with different polymer concentrations; Figure 11 : Output performance diagram of the sensor under external force stimulation; Figure 12 : A schematic diagram illustrating the highest frequency response achievable by a highly elastic, low-viscosity gel formed based on topological entanglement and moderate cross-linking; Figure 13 : A schematic diagram illustrating the cyclic stability achievable by a highly elastic, low-viscosity gel formed based on topological entanglement and moderate cross-linking. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] A method for fabricating ion-electron sensors based on entangled polymer networks includes the following steps: S1, Preparation of the initial polymer: Acrylamide monomer is dissolved in deionized water, and the molar ratio of deionized water to acrylamide monomer is adjusted to prepare initial polymers with different concentrations.

[0018] The molar ratios of deionized water to acrylamide monomers were 2, 4, 8, and 12, respectively.

[0019] S2, Preparation of prepolymer solution: Crosslinking agent and initiator are added to initial polymers of different concentrations. For each concentration of initial polymer, the molar ratio of crosslinking agent to acrylamide monomer is adjusted, and then the molar amount of initiator is adjusted to keep the molar ratio of crosslinking agent to initiator constant. After stirring, the mixture is ultrasonically treated to prepare prepolymer solutions with different crosslinking densities.

[0020] The molar ratio of crosslinking agent to acrylamide monomer is 3.2 × 10⁻⁶. -7 3.2×10 -5 3.2×10 -3 and 3.2×10 -2 The molar ratio of crosslinking agent to initiator is 0.4.

[0021] The crosslinking agent is N,N'-methylenebisacrylamide; the initiator is 2,2-dimethoxy-2-phenylacetophenone.

[0022] Different crosslinking densities and polymer concentrations can form different numbers of crosslinking points and entanglements due to the different crosslinking points and polymer concentrations, resulting in pore structures of different sizes.

[0023] Modulation of the viscoelastic properties of the sensor's intermediate layer gel: The viscoelasticity of the sensor's intermediate layer gel can be modulated by changing the polymer concentration and crosslinking density.

[0024] like Figures 3-8 As shown, the number of crosslinking points per unit volume can be controlled by changing the crosslinking density. The more crosslinks there are, the more obvious the gel solidification effect and the stronger the rigidity. However, too much crosslinking agent can easily lead to an increase in the number of short polymer chains after gel polymerization, resulting in poor gel toughness and easy breakage. After deformation under stress, the energy dissipation due to inter-chain breakage increases. The fewer crosslinks there are, the fewer chemical fixation points between polymer chains, making the gel prone to inter-chain slippage. The gel is more viscous, and after deformation, the polymer chains are prone to excessive slippage, causing the gel energy dissipation to be unable to return to its original state.

[0025] Under appropriate crosslinking density, the physical entanglement between polymer chains can be increased by adjusting the polymer concentration, replacing the role of chemical crosslinking points in fixing the polymer chains. During deformation under stress, the fixation by a small number of crosslinking points enables chain fixation, and the physical entanglement between chains allows for small-scale physical slippage, resulting in rapid rebound over short timescales. By controlling the crosslinking density and polymer concentration, a highly entangled polymer network can be achieved, resulting in macroscopically uniform porosity and significantly improving the viscoelastic properties of the gel.

[0026] For example, the molar ratio of crosslinking agent to acrylamide monomer is 3.2 × 10⁻⁶. -5 By changing the molar ratio of deionized water to acrylamide monomer (2, 4, 8, 12), the pore size can be gradually increased, the gel viscosity can be gradually increased, and the elasticity can be gradually decreased.

[0027] The relationship between the viscoelasticity of the sensor's intermediate gel and its high-frequency response capability: like Figures 9-10 As shown, by controlling different crosslinking densities and polymer concentrations, gels with varying viscoelasticities can be formed. Better elasticity corresponds to poorer viscosity, resulting in a shorter recovery time after deformation and a stronger high-frequency response. Using a moderately crosslinked, high-polymer-concentration prepolymer solution, a highly elastic, low-viscosity interlayer material can be achieved.

[0028] S3, Preparation of the sensor interlayer gel: The prepolymer solution is injected into a polytetrafluoroethylene (PTFE) mold through a dropper. The PTFE mold is then placed under a UV lamp to complete the polymerization reaction. The PTFE mold has a conical cavity to create conical protrusions on the molded sensor interlayer gel. The molded sensor interlayer gel is then demolded and immersed in deionized water for spontaneous swelling. The polytetrafluoroethylene mold has a thickness of 2mm, 9×9 conical cavities, a bottom diameter of 0.5mm, and a height of 0.5mm.

[0029] The ultraviolet light emitted by the ultraviolet lamp has a wavelength of 365nm, and the irradiation time is 4 hours. The spontaneous swelling time in deionized water is 24 hours.

[0030] The prepared sensor intermediate layer gel, such as Figure 2 As shown.

[0031] The sensor intermediate gel was tested after it had fully swollen.

[0032] S4, Preparation of sensor electrode: A gold conductive film is sputtered onto the surface of a PET substrate using a metal sputtering instrument to form a flexible electrode. The flexible electrode is then cut using a CO2 laser cutter. A copper wire is led out from one end of the cut flexible electrode. The gold conductive film is connected to the copper wire using conductive silver paste. After the conductive silver paste is cured, the flexible electrode is encapsulated using PI tape.

[0033] The thickness of the gold conductive film is 35nm, and the size of the flexible electrode after cutting is 15mm×15mm.

[0034] S5, Sensor fabrication: The sensor intermediate gel is used as the intermediate layer of the sensor. Both the upper and lower sides of the sensor intermediate gel are PET / Au composite flexible electrodes. The lower flexible electrode is in contact with and fixed to the side of the sensor intermediate gel away from the conical protrusion, while the upper flexible electrode is in critical contact with and fixed to the sensor intermediate gel.

[0035] "Critical contact state" refers to a special contact mode between the sensor's intermediate gel and the upper flexible electrode. In this state, the flexible electrode and the sensor's intermediate gel are not in complete close contact, nor are they completely separated. Instead, they are in an edge state where they are about to make contact but have not yet formed a stable mechanical connection. This optimizes the sensor's performance, such as improving sensitivity, response speed, or linearity.

[0036] The fabricated ion electronic sensor, such as Figure 1 As shown.

[0037] Sensor output performance under different dynamic force stimuli: like Figure 11 As shown, the sensor interlayer gel, formed by high inter-chain entanglement and moderate cross-linking, has excellent mechanical properties and achieves dynamic response under high stress.

[0038] like Figure 12 As shown, based on the conical protrusions on the surface, the sensor's intermediate gel layer can still achieve a fast response of up to 800Hz at an amplitude of 0.1mm.

[0039] like Figure 13As shown, due to the high polymer concentration, the water loss rate of the sensor intermediate layer gel is reduced at room temperature, and the sensor intermediate layer gel can achieve a stable cycle response of 100,000 times.

[0040] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A method for fabricating ion-electron sensors based on entangled polymer networks, characterized in that, Includes the following steps: S1, Preparation of the initial polymer: Dissolve acrylamide monomer in deionized water, adjust the molar ratio of deionized water to acrylamide monomer, and prepare initial polymers with different concentrations. S2, Preparation of prepolymer solution: Crosslinking agent and initiator are added to initial polymers of different concentrations. For each concentration of initial polymer, the molar ratio of crosslinking agent to acrylamide monomer is adjusted, and then the molar amount of initiator is adjusted to keep the molar ratio of crosslinking agent to initiator constant. After stirring, the mixture is ultrasonically treated to prepare prepolymer solutions with different crosslinking densities. S3, Preparation of sensor intermediate layer gel: The prepolymer solution is injected into the polytetrafluoroethylene mold through a dropper, and then the polytetrafluoroethylene mold is placed under ultraviolet light to complete the polymerization reaction. The polytetrafluoroethylene mold has a conical cavity so that the sensor intermediate gel after molding has conical protrusions. The sensor intermediate gel after molding is demolded and soaked in deionized water to spontaneously swell. S4, Preparation of sensor electrode: A gold conductive film is sputtered onto the surface of a PET substrate using a metal sputtering instrument to form a flexible electrode. The flexible electrode is then cut using a CO2 laser cutter. A copper wire is led out from one end of the cut flexible electrode. The gold conductive film is connected to the copper wire using conductive silver paste. After the conductive silver paste is cured, the flexible electrode is encapsulated using PI tape. S5, Sensor fabrication: The sensor intermediate gel is used as the intermediate layer of the sensor. Both the upper and lower sides of the sensor intermediate gel are PET / Au composite flexible electrodes. The lower flexible electrode is in contact with and fixed to the side of the sensor intermediate gel away from the conical protrusion, while the upper flexible electrode is in critical contact with and fixed to the sensor intermediate gel.

2. The method for fabricating an ion-electron sensor based on an entangled polymer network according to claim 1, characterized in that, In step S1, the molar ratios of deionized water to acrylamide monomer are 2, 4, 8, and 12, respectively.

3. The method for fabricating an ion-electron sensor based on an entangled polymer network according to claim 1, characterized in that, In step S2, the molar ratio of crosslinking agent to acrylamide monomer is 3.2 × 10⁻⁶. -7 3.2×10 -5 3.2×10 -3 and 3.2×10 -2 The molar ratio of crosslinking agent to initiator is 0.

4.

4. The method for fabricating an ion-electron sensor based on an entangled polymer network according to claim 1, characterized in that, In step S2, the crosslinking agent is N,N'-methylenebisacrylamide; the initiator is 2,2-dimethoxy-2-phenylacetophenone.

5. The method for fabricating an ion-electron sensor based on an entangled polymer network according to claim 1, characterized in that, In step S3, the thickness of the polytetrafluoroethylene mold is 2mm, the number of conical cavities is 9×9, the bottom diameter of the conical cavity is 0.5mm, and the height of the conical cavity is 0.5mm.

6. The method for fabricating an ion-electron sensor based on an entangled polymer network according to claim 1, characterized in that, In step S3, the ultraviolet light emitted by the ultraviolet lamp has a wavelength of 365nm, the irradiation time is 4h, and the spontaneous swelling time in deionized water is 24h.

7. The method for fabricating an ion-electron sensor based on an entangled polymer network according to claim 1, characterized in that, In step S4, the thickness of the gold conductive film is 35nm, and the size of the flexible electrode after cutting is 15mm×15mm.

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