Electrode plate for pressure monitoring sensor, method for manufacturing the same, and sensor

Abstract

The application belongs to the field of sensors, and particularly relates to a polar plate of a pressure monitoring sensor, a preparation method of the polar plate and the sensor. The polar plate comprises: a polymer film, at least one side surface of the polymer film having a convex array, the convex being in an arch shape, and the elastic modulus of the arch-shaped convex being gradiently increased from a bottom to a top; an electrode layer attached to the side of the polymer film where the convex array is located; and the sensitivity of the sensor in high-pressure response can be improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of sensors, and particularly relates to a polar plate of a pressure monitoring sensor and a preparation method and sensor thereof. BACKGROUND

[0002] Body weight, muscle strength and coordination, movement patterns and posture, activity volume and intensity, joint structure and alignment, external loads, and ground reaction forces, etc. will bring pressure to the knee joint of the human body. The knee joint is one of the most complex and largest weight-bearing joints in the human body, and excessive pressure on the knee joint is easy to cause pain, strain (such as patellar tendonitis and bursitis), and cartilage wear (osteoarthritis). Effective monitoring of knee joint pressure is crucial for preventing injuries, guiding rehabilitation, optimizing athletic performance, osteoarthritis management, postoperative recovery, etc.

[0003] Flexible wearable pressure sensors can be used in the field of knee joint pressure monitoring, etc. However, when the sensor is subjected to a large pressure, the sensitivity of the response is limited, which affects the accurate sensing of the pressure.

[0004] It should be noted that this part of the present application only provides background technology related to the present application, and does not necessarily constitute prior art or public knowledge. SUMMARY

[0005] The purpose of the present application is to overcome the defects of the prior art pressure sensor in monitoring the knee joint pressure, etc. when the sensor is subjected to a large pressure, the sensitivity of the response is limited, which affects the accurate sensing of the pressure. The present application provides a polar plate of a pressure monitoring sensor and a preparation method and sensor thereof, which can improve the sensitivity of the high-pressure response of the sensor.

[0006] In order to achieve the above-mentioned purpose, in a first aspect, the present application provides a polar plate of a pressure monitoring sensor, comprising:

[0007] A polymer film, at least one side surface of the polymer film has an array of protrusions, the shape of the protrusion is arched, and the elastic modulus of the arched protrusion increases from the bottom to the top in a gradient;

[0008] An electrode layer attached to the side of the polymer film where the array of protrusions is located.

[0009] In some preferred embodiments, the arch height of the arched protrusion is 30-60pm, the radius of curvature is 100-250pm, and the spacing between adjacent arched protrusions is 150-400pm.

[0010] In some preferred embodiments, BaTiO3 particles are distributed in the arched protrusion, the particle size of the BaTiO3 particles is 50-300nm, and the BaTiO3 particles include a BaTiO3 core and a cetyltrimethylammonium bromide coating layer.

[0011] Preferably, the concentration gradient of BaTiO3 particles increases from the bottom to the top of the arch-shaped protrusion.

[0012] In some preferred embodiments, the polymer of the polymer thin film comprises polydimethylsiloxane.

[0013] In a second aspect, the present application provides a method for preparing the electrode plate of the first aspect, comprising:

[0014] uniformly dispersing the charged particles in a polymer prepolymer to obtain a dispersion liquid, injecting the dispersion liquid into a microfluidic chip, and preparing the dispersion liquid into a polymer thin film by micro-electrofluidic 3D printing under the environment of applying a direct current electric field, the microfluidic chip comprising an optical fiber, an electrode, and a dispersion liquid extrusion passage, at least one side surface of the polymer thin film having an array of protrusions, the protrusions being in the shape of an arch, the arch-shaped protrusions having a concentration gradient of the charged particles increasing from the bottom to the top;

[0015] Preferably, an electrode layer is prepared on the side of the polymer thin film where the array of protrusions is located.

[0016] In some preferred embodiments, the polymer is polydimethylsiloxane, the charged particles are BaTiO3 particles with a particle size of 50 nm to 300 nm, the BaTiO3 particles comprise a BaTiO3 core and a cetyltrimethylammonium bromide coating layer, the ratio of the diameter of the core to the thickness of the coating layer is 4 to 20, the mass ratio of the BaTiO3 particles to the polydimethylsiloxane prepolymer in the dispersion liquid is 1:3.5 to 1:4.5, and the field strength of the direct current electric field is 150 V / mm to 250 V / mm.

[0017] In some preferred embodiments, the conditions of micro-electrofluidic 3D printing comprise: ultraviolet in-situ curing, light intensity of 30 mW / cm 2 ~85 mW / cm 2 , and exposure time of 10 s to 30 s.

[0018] In a third aspect, the present application provides a sensor for pressure monitoring, comprising:

[0019] an electrode plate comprising a first electrode plate and a second electrode plate stacked in sequence, the second electrode plate being the electrode plate of the first aspect or the electrode plate prepared by the method of preparing the electrode plate of the second aspect;

[0020] A sensitive layer is stacked between the first electrode plate and the second electrode plate, the sensitive layer comprises a gel film, a substrate of the gel film comprises a polymer ionic liquid gel, and nanoparticles are doped in the gel film, the nanoparticles comprise a core and a coating layer covering the surface of the core, the core comprises Fe3O4, and the coating layer comprises polyaniline, the elastic modulus of the gel film changes in a gradient along the thickness direction of the gel film, the concentration of the nanoparticles changes in a gradient along the thickness direction of the gel film, the direction of the gradient change of the elastic modulus is consistent with the direction of the gradient change of the concentration, and the side with a higher elastic modulus of the gel film is arranged close to the second electrode plate.

[0021] In a fourth aspect, the present application provides a sensor for monitoring pressure of a knee joint, which is the sensor for monitoring pressure according to the third aspect.

[0022] The electrode plate of the present application has an array of protrusions on at least one side surface of the polymer film, the protrusions are in the shape of arches, and an electrode layer is attached to the side of the polymer film where the array of protrusions is located. When the electrode plate is used as an electrode plate of a pressure monitoring sensor, the contact area of the arches changes when the arches are pressed, the top of the arches is coupled to the sensitive layer to generate a capacitance signal, the arches and the electrode on the other side of the sensitive layer form an interfacial capacitance, the interfacial capacitance changes when the arches are pressed to generate an electrostatic signal, the signal strength of the high pressure response of the sensor can be improved, thereby improving the response sensitivity of the sensor when a larger pressure is applied, the elastic modulus of the arches increases in a gradient from the bottom to the top, and the signal strength of the high pressure response of the sensor and the response sensitivity can be further improved, thereby increasing the response sensitivity of the sensor when a larger pressure is applied.

[0023] The preparation method of the electrode plate of the present application comprises the following steps: before 3D printing, a dispersion liquid is injected into a microfluidic chip pipeline, the microfluidic chip pipeline comprises a coaxial dispersion liquid extrusion channel, an optical fiber channel and a top electrode channel, a bottom electrode is processed on a polymer substrate, a direct current electric field is applied between the top electrode and the bottom electrode after the microfluidic chip pipeline extrudes a microdroplet, charged particles are induced to migrate, a concentration gradient of the charged particles is formed, the side with a high concentration of the charged particles has a high elastic modulus, and the side with a low concentration of the charged particles has a low elastic modulus, thereby forming an elastic modulus gradient, the migration of the charged particles also changes the interface characteristics of the dispersion liquid, and the polymer prepolymer is driven to flow, thereby inducing an arch structure. After the arch structure is formed, the optical fiber channel is input with ultraviolet light to cure and form the polymer prepolymer. The preparation method of the electrode plate of the present application injects the dispersion liquid into the microfluidic chip, and prepares the dispersion liquid into a polymer film by microfluidic 3D printing under the environment of applying a direct current electric field, thereby effectively improving the customization processing of the size, spacing and area of the arch structure, and improving the performance of the sensor and the device processing efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be considered as a limitation to the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0025] Figure 1 A cross-sectional view of a pressure sensor of the present application.

[0026] Legend of reference signs:

[0027] 1, upper electrode plate; 11, flexible substrate layer; 12, hydrogen-bonded polymer layer; 2, lower electrode plate; 3, gel thin film sensitive layer. DETAILED DESCRIPTION

[0028] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values are understood to be approximate values. The endpoints of the ranges and any values should be considered to be open-ended ranges for purposes of the disclosure, unless otherwise specified. Thus, the endpoints of the ranges and any values are not limited to the precise values stated.

[0029] The inventor of the present application has found that the existing pressure sensor has limited sensitivity in response when monitoring the pressure of the knee joint, and the accurate sensing of the pressure is affected.

[0030] To this end, in a first aspect, the present application provides an electrode plate of a pressure monitoring sensor, comprising:

[0031] A polymer film, at least one side surface of the polymer film having an array of protrusions, the protrusions being in the shape of an arch, the arch-shaped protrusions having a gradient increase in elastic modulus from the bottom to the top;

[0032] An electrode layer attached to the side of the polymer film on which the array of protrusions is located.

[0033] The arch-shaped protrusions of the electrode plate of the present application have a gradient increase in elastic modulus from the bottom to the top, which can further improve the signal strength and response sensitivity of the sensor under high pressure, and increase the response sensitivity of the sensor under greater pressure.

[0034] In some preferred embodiments, the arch height of the arch-shaped protrusions is 30-60 μm, the radius of curvature is 100-250 μm, and the spacing between adjacent arch-shaped protrusions is 150-400 μm. Under this preferred scheme, based on the gradient increase in elastic modulus of the arch-shaped protrusions from the bottom to the top, the arch height of the arch-shaped protrusions is 30-60 μm, the radius of curvature of the arch-shaped protrusions is 100-250 μm, and the spacing between adjacent arch-shaped protrusions is 150-400 μm, which is more conducive to improving the sensitivity of the sensor. The spacing between adjacent arch-shaped protrusions refers to the distance between the central axes of adjacent arch-shaped protrusions. The arch height is preferably 35-55 μm, more preferably 40-50 μm, the radius of curvature is preferably 120-230 μm, more preferably 150-200 μm, and the spacing between adjacent arch-shaped protrusions is preferably 200-350 μm, more preferably 250-300 μm.

[0035] In some preferred embodiments, the arch-shaped protrusions contain BaTiO3 particles, the particle size of the BaTiO3 particles is 50-300 nm, and the BaTiO3 particles include a BaTiO3 core and a cetyltrimethylammonium bromide coating layer.

[0036] Preferably, the concentration of the BaTiO3 particles increases in a gradient from the bottom to the top of the arch-shaped protrusions. The present application does not limit the method for characterizing the concentration of the BaTiO3 particles, for example, a scanning electron microscope can be used to measure and calculate the area ratio of the BaTiO3 particles in the cross section perpendicular to the arch height of the arch-shaped protrusions.

[0037] In some preferred embodiments, the polymer of the polymer film includes polydimethylsiloxane.

[0038] In a second aspect, the present application provides a preparation method of the electrode plate of the first aspect, comprising:

[0039] The charged particles are uniformly dispersed in a polymer prepolymer to obtain a dispersion liquid, the dispersion liquid is injected into a microfluidic chip, the dispersion liquid is prepared into a polymer film by micro-electrofluid 3D printing under the environment of applying a direct current electric field, the microfluidic chip comprises an optical fiber, an electrode and a dispersion liquid extrusion channel, at least one side surface of the polymer film has a convex array, the shape of the convex is an arch shape, the arch-shaped convex increases from the bottom to the top, and the concentration gradient of the charged particles increases.

[0040] An electrode layer is prepared on the side of the polymer film where the convex array is located.

[0041] The preparation method of the polar plate, before 3D printing, the dispersion liquid is injected into a microfluidic chip pipeline, the microfluidic chip pipeline comprises a coaxial dispersion liquid extrusion channel, an optical fiber channel and a top electrode channel, a bottom electrode is processed on a polymer substrate, a direct current electric field is applied between the top electrode and the bottom electrode after the dispersion liquid extrusion channel extrudes a microdroplet, the charged particles are induced to migrate, the charged particles form a concentration gradient, the side with high concentration of charged particles has high elastic modulus, the side with low concentration of charged particles has low elastic modulus, a gradient of elastic modulus can be formed, the migration of the charged particles also changes the interface characteristics of the dispersion liquid, the polymer prepolymer is driven to flow, and thus an arch-shaped structure is induced. After the arch-shaped structure is formed, the optical fiber channel is connected to ultraviolet light, and the polymer prepolymer is cured and formed.

[0042] The dispersion liquid is injected into a microfluidic chip, the dispersion liquid is prepared into a polymer film by micro-electrofluid 3D printing under the environment of applying a direct current electric field, the size, spacing and area of the arch-shaped structure can be effectively customized, and the performance of the sensor and the device processing efficiency are improved.

[0043] In some preferred embodiments, the polymer is polydimethylsiloxane, the charged particles are BaTiO3 particles with a particle size of 50-300 nm, the BaTiO3 particles comprise a BaTiO3 core and a cetyltrimethylammonium bromide coating layer, the ratio of the diameter of the core to the thickness of the coating layer is 4-20, the mass ratio of the BaTiO3 particles to the polydimethylsiloxane prepolymer in the dispersion is 1:3.5-1:4.5, and the field strength of the direct current electric field is 150-250 V / mm. In this preferred scheme, the elastic modulus of the bottom and the top of the arch-shaped protrusion is adjusted, which is more conducive to improving the signal strength and response sensitivity of the sensor under high pressure. In order to improve the high-pressure response sensitivity, the ratio of the diameter of the core to the thickness of the coating layer is preferably 6-16, and more preferably 9-12, and the particle size of the BaTiO3 particles is preferably 100-250 nm, and more preferably 150-200 nm. The polymer is polydimethylsiloxane, the charged particles are BaTiO3 particles, the system has better stability, and it is also more conducive to stably increasing the elastic modulus of the arch-shaped protrusion from the bottom to the top, thereby improving the pressure sensing accuracy. The charged particles are BaTiO3 particles, which is also more conducive to forming a charged particle distribution state in which the concentration of the charged particles increases from the bottom to the top under the action of the direct current electric field. The BaTiO3 particles are positively charged, and the direction of the direct current electric field is from the lower part of the arch-shaped protrusion to the upper part of the arch-shaped protrusion.

[0044] In some preferred embodiments, the conditions of the micro-fluid 3D printing include: in-situ UV curing, light intensity is 30-85 mW / cm 2 ~85mW / cm 2 , and the exposure time is 10-30 s.

[0045] In a third aspect, the present application provides a sensor for pressure monitoring, comprising:

[0046] a polar plate comprising a first polar plate and a second polar plate stacked in sequence, wherein the second polar plate is the polar plate prepared by the preparation method of the polar plate in the first aspect or the polar plate in the second aspect;

[0047] a sensitive layer stacked between the first polar plate and the second polar plate, wherein the sensitive layer comprises a gel film, the substrate of the gel film comprises a polymer ionic liquid gel, and the gel film is doped with nanoparticles, the nanoparticles comprise a core and a coating layer coated on the surface of the core, the core comprises Fe3O4, and the coating layer comprises polyaniline; along the thickness direction of the gel film, the elastic modulus of the gel film and the concentration of the nanoparticles change in a gradient manner, the direction of the gradient change of the elastic modulus is consistent with the direction of the gradient change of the concentration, and the side of the gel film with a higher elastic modulus is arranged close to the second polar plate.

[0048] The second electrode plate of the sensor of the present application has a convex array on at least one side surface of the polymer film, the convexes are in the shape of arches, the electrode layer is attached to the side of the polymer film where the convex array is located, the contact area changes when the arches are pressed, the sensitivity of the high pressure response of the sensor can be improved, the top of the arches is coupled with the sensitive layer to generate a capacitance signal, the arches and the electrodes of the first electrode plate form an interfacial capacitance, the interfacial capacitance changes when the arches are pressed to generate an electrostatic signal, the signal strength of the high pressure response of the sensor can be improved, thereby improving the response sensitivity of the sensor when it is subjected to a larger pressure, the elastic modulus of the arches increases in a gradient from the bottom to the top, the signal strength and the response sensitivity of the high pressure response of the sensor can be further improved, and the response sensitivity of the sensor when it is subjected to a larger pressure is increased; the base material of the gel film is a polymer ionic liquid gel, the coating layer of the nanoparticles doped in the gel film includes polyaniline, the polyaniline coating layer forms a conductive path in the gel film as a "conductive network", the gel film can be used as the sensitive layer of the pressure sensor, the elastic modulus of the gel film changes in a gradient along the thickness direction of the gel film, when the pressure is low, the side of the gel film with a lower elastic modulus deforms obviously, the signal strength of the low pressure region of the pressure sensor can be improved, and the low pressure sensitivity is improved, because the elastic modulus of one side of the gel film is higher, the upper limit of the sensing range of the sensor can be widened, the sensing range is widened, when the pressure is high, the elastic modulus of one side of the gel film is higher, the deformation of the gel film is relatively small, and the concentration of the nanoparticles with the polyaniline coating layer on the side of the gel film with a higher elastic modulus is also relatively high, through the higher elastic modulus and the higher concentration of the nanoparticles on one side of the gel film, the signal strength of the high pressure region of the sensor can be improved while the upper limit of the sensing range of the sensor is widened, and the high pressure sensitivity is improved. The nanoparticles with Fe3O4 as the core are doped in the gel film, by applying an external magnetic field, the elastic modulus distribution of the gel film can be controlled, the stiffness distribution of the sensor can be changed adaptively according to the motion state of the knee joint, etc., so that when the sensor is subjected to a strong pressure, the sensor can resist the pressure and not exceed the sensing range.

[0049] In a fourth aspect, the present application provides a sensor for monitoring the pressure of a knee joint, which is the sensor for monitoring the pressure according to the third aspect.

[0050] In a fifth aspect, the present application provides a pressure sensor, referring to Figure 1 , which comprises an upper electrode plate 1, a lower electrode plate 2 and a gel film sensitive layer 3 stacked between the upper electrode plate 1 and the lower electrode plate 2 in sequence;

[0051] The upper electrode plate 1 comprises a flexible substrate layer 11 and a hydrogen-bond-containing polymer layer 12 stacked together, the hydrogen-bond-containing polymer layer 12 has a directional crack network on the side away from the flexible substrate layer 11, the cracks in the directional crack network have a consistent direction, and further comprises an electrode layer (not shown in the figure) continuously attached to the side of the hydrogen-bond-containing polymer layer 12 where the directional crack network is located, the electrode layer is attached to the inner surface of the cracks and the surface of the crack edges.

[0052] The gel film sensitive layer 3 comprises a gel film, the substrate of the gel film comprises a polymer ionic liquid gel, and the gel film is doped with nanoparticles (not shown in the figure), the nanoparticles comprise a core and a coating layer covering the surface of the core, the core comprises Fe3O4, and the coating layer comprises polyaniline; along the thickness direction of the gel film, the elastic modulus of the gel film and the concentration of the nanoparticles change in a gradient manner, the direction of the gradient change of the elastic modulus is consistent with the direction of the gradient change of the concentration, and the side of the gel film with a lower elastic modulus is arranged close to the upper electrode plate 1.

[0053] The lower electrode plate 2 comprises a polymer film and an electrode layer, one side surface of the polymer film has an array of protrusions, the protrusions are in the shape of arches, the elastic modulus of the arch-shaped protrusions increases in a gradient manner from the bottom to the top, and the electrode layer is attached to the side of the polymer film where the array of protrusions is located.

[0054] The material of the electrode layer of the upper electrode plate is preferably a conductive polymer / silver nanowire composite layer, and the conductive polymer is further preferably a conductive polymer composed of poly(3,4-ethylenedioxythiophene) / polystyrene sulfonic acid; the material of the electrode layer of the lower electrode plate is not limited in the present application, for example, the electrode layer is a Ti / Au electrode; and the thickness of the electrode layer is also not limited in the present application, for example, the thickness of the electrode layer is 80 nm to 120 nm.

[0055] The upper electrode plate of the pressure sensor comprises a hydrogen-bond-containing polymer layer, the side of the hydrogen-bond-containing polymer layer away from the flexible substrate layer has a directional crack network, the cracks in the directional crack network have a consistent direction, when the pressure sensor is subjected to pressure, the cracks are deformed by opening, the area of the electrode plate in contact with the sensitive layer is increased, a pressure-capacitance signal is generated, and the response sensitivity of the pressure sensor to smaller pressure can be improved; when the pressure sensor is subjected to larger or more frequent pressure, the cracks are prone to breakage, which is manifested as small cracks extending from the periphery of the directional cracks, affecting the sensing accuracy and the service life of the sensor; when the pressure sensor is subjected to smaller pressure for a period of time, the width of the extended small cracks is shortened to the distance between the molecular forces, and the extended small cracks can be eliminated through self-repairing by hydrogen bonds, the broken cracks can be repaired, the sensing accuracy and the service life of the sensor can be improved.

[0056] The gel thin film sensitive layer 3 of the present application is a polymer ionic liquid gel, the coating layer of the nanoparticles doped in the gel thin film comprises polyaniline, the polyaniline coating layer forms a conductive path in the gel thin film as a "wire network", the gel thin film can be used as a sensitive layer of a pressure sensor, along the thickness direction of the gel thin film, the elastic modulus of the gel thin film changes in gradient, when the pressure is low, the side of the gel thin film with lower elastic modulus deforms obviously, which can improve the signal intensity of the pressure sensor in the low pressure area and improve the low pressure sensitivity, because the elastic modulus of one side of the gel thin film is higher, the upper limit of the sensing range of the sensor can be widened, when the pressure is high, the elastic modulus of one side of the gel thin film is higher, the deformation of the gel thin film is relatively small, and the concentration of the nanoparticles with the polyaniline coating layer on the side of the gel thin film with higher elastic modulus is also relatively high, through the higher elastic modulus of one side of the gel thin film and the higher concentration of the nanoparticles, the signal intensity of the sensor in the high pressure area can be improved while the upper limit of the sensing range is widened, and the high pressure sensitivity is improved. The nanoparticles with Fe3O4 as the core are doped in the gel thin film, and the elastic modulus distribution of the gel thin film can be controlled by applying an external magnetic field, so that the stiffness distribution of the sensor changes adaptively with the motion state of the knee joint, thereby preventing the sensor from being unable to resist the pressure and exceeding the sensing range when the sensor is subjected to strong pressure.

[0057] The lower plate of the pressure sensor of the present application, one side surface of the polymer film has an array of protrusions, the shape of the protrusions is arched, the electrode layer is attached to the side of the polymer film where the array of protrusions is located, the contact area changes when the arch is pressed, which can improve the sensitivity of the pressure sensor in response to a larger pressure, the top of the arch is coupled with the sensitive layer to generate a capacitance signal, the arch electrode and the electrode of the upper plate form an interfacial capacitance, the interfacial capacitance changes to generate an electrostatic signal when the arch is pressed, which can improve the signal intensity of the pressure sensor in response to a larger pressure, thereby improving the response sensitivity of the sensor to a larger pressure, the elastic modulus of the arch protrusion increases in gradient from the bottom to the top, which can further improve the response sensitivity of the pressure sensor to a larger pressure.

[0058] In a sixth aspect, the present application provides a pressure sensor for a knee joint, which is the pressure sensor of the fifth aspect.

[0059] The present application will be further described in detail below in combination with specific embodiments.

[0060] Embodiment 1

[0061] A pressure sensor comprises: a first electrode plate and a second electrode plate stacked in sequence, the second electrode plate comprising a polymer film and an electrode layer, one side surface of the polymer film having an array of protrusions, the protrusions being in the shape of arches, the polymer of the polymer film being polydimethylsiloxane, the arches having a height of 45 μm and a radius of curvature of 175 μm, the spacing between adjacent arches being 275 μm, the elastic modulus of the arches increasing in a gradient from the bottom to the top, the arches containing BaTiO3 particles, the BaTiO3 particles having a particle size of about 175 nm, the BaTiO3 particles comprising a BaTiO3 core and a cetyltrimethylammonium bromide coating layer, the concentration of the BaTiO3 particles increasing in a gradient from the bottom to the top of the arches, the electrode layer being attached to the side of the polymer film on which the array of protrusions is located.

[0062] A sensitive layer is stacked between the first electrode plate and the second electrode plate, and the sensitive layer comprises a gel film, the base material of the gel film comprising a polymer ionic liquid gel, the gel film containing nanoparticles, the nanoparticles comprising a core and a coating layer coated on the surface of the core, the core comprising Fe3O4 and the coating layer comprising polyaniline, the elastic modulus of the gel film and the concentration of the nanoparticles varying in a gradient along the thickness direction of the gel film, the direction of the gradient variation of the elastic modulus being consistent with the direction of the gradient variation of the concentration, and the side of the gel film with a higher elastic modulus being arranged close to the second electrode plate.

[0063] A method for preparing the second electrode plate described above, comprising:

[0064] Step 1: uniformly dispersing BaTiO3 particles with a particle size of about 175 nm in polydimethylsiloxane prepolymer to obtain a dispersion liquid, the mass ratio of the BaTiO3 particles to the polydimethylsiloxane prepolymer in the dispersion liquid being 1:4, the BaTiO3 particles comprising a BaTiO3 core and a cetyltrimethylammonium bromide coating layer, and the ratio of the diameter of the core to the thickness of the coating layer being about 10;

[0065] Step 2: injecting the dispersion liquid of Step 1 into a microfluidic chip, the microfluidic chip comprising an optical fiber, an electrode and a dispersion liquid extrusion channel, and preparing the polymer film of Step 1 into a polymer film by micro-electrofluidic 3D printing in an environment with a direct current electric field, one side surface of the polymer film having an array of protrusions, the protrusions being in the shape of arches, the concentration of the BaTiO3 particles increasing in a gradient from the bottom to the top of the arches, and the field strength of the direct current electric field being 200 V / mm; the conditions of the micro-electrofluidic 3D printing comprising: ultraviolet in-situ curing, light intensity being 60 mW / cm 2 , and exposure time being 20 s;

[0066] Step 3: preparing an electrode layer on the side of the polymer film on which the array of protrusions is located.

[0067] Example 2

[0068] Referring to the preparation method of the second electrode plate of Example 1, except that the BaTiO3 particles include a BaTiO3 core and a cetyltrimethylammonium bromide coating layer and the ratio of the diameter of the core to the thickness of the coating layer is about 8.

[0069] Example 3

[0070] Referring to the pressure sensor of Example 1, except that the height of the arch-shaped protrusions is 20 μm.

[0071] Example 4

[0072] Referring to the pressure sensor of Example 1, except that the spacing between adjacent arch-shaped protrusions is 500 μm.

[0073] Comparative Example 1

[0074] Referring to the preparation method of the second electrode plate of Example 1, except that the dispersion liquid is prepared into a polymer film having an array of protrusions on one side surface by using a general 3D printing method, the BaTiO3 particles are uniformly distributed in the arch-shaped protrusions, there is no obvious concentration gradient of the BaTiO3 particles, and referring to the pressure sensor of Example 1, the elastic modulus of the arch-shaped protrusions has no obvious gradient change from the bottom to the top.

[0075] Comparative Example 2

[0076] Referring to the preparation method of the second electrode plate of Example 1, except that the dispersion liquid is directly prepared into a polymer film (without arch-shaped protrusions), and the polymer film uniformly disperses the BaTiO3 particles.

[0077] Test Example

[0078] The pressure sensors obtained in the above examples and comparative examples are tested for low-pressure sensitivity and high-pressure sensitivity. The testing method for low-pressure sensitivity is to load pressure in steps of 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa from 0 MPa in 5 points; each point is kept for 60 seconds, and the positive stroke output value is recorded; the reverse unloading is to 0 MPa, and the reverse stroke output value is recorded, 3 cycles are completed; and the low-pressure region working straight line slope is calculated. The testing method for high-pressure sensitivity is to load in 5 points of 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa from 0.6 MPa; each point is kept for 60 seconds, and the positive stroke output is recorded; the overloading stability is detected at 1.0 MPa for 1 minute; and the high-pressure sensitivity slope is calculated. The test results are shown in Table 1.

[0079] Table 1

[0080]

[0081] Compared with the comparative examples and the reference example, the arched protrusions on the polymer film can improve the high pressure sensitivity of the sensor, the elastic modulus of the arched protrusions is gradiently increased from the bottom to the top, and the high pressure sensitivity of the sensor can be further improved.

[0082] Compared with the comparative example 1 and the example 2, the ratio of the diameter of the core of the BaTiO3 particle to the thickness of the coating layer is 9-12, which is more conducive to improving the high pressure sensitivity and the low pressure sensitivity of the sensor, compared with the comparative example 1 and the example 3, the arch height of the arched protrusion is 30-60 μm, which is more conducive to improving the high pressure sensitivity and the low pressure sensitivity of the sensor, compared with the comparative example 1 and the example 4, the interval between the adjacent arched protrusions is 150-400 μm, which is more conducive to improving the high pressure sensitivity and the low pressure sensitivity of the sensor.

[0083] The preferred embodiments of the application are described in detail above, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the application and fall within the protection scope of the application.

Claims

1. An electrode plate of a pressure monitoring sensor, characterized in that, include: A polymer film, wherein at least one side surface of the polymer film has an array of protrusions, the protrusions being arched in shape, and the elastic modulus of the arched protrusions increasing in a gradient from bottom to top; An electrode layer is attached to the side of the polymer film containing the protrusion array.

2. The electrode plate according to claim 1, characterized in that, The arch height of the arched protrusion is 30μm-60μm, the radius of curvature is 100μm-250μm, and the interval between adjacent arched protrusions is 150μm-400μm.

3. The electrode plate according to claim 1, characterized in that, The arched protrusion contains BaTiO3 particles with a particle size of 50nm to 300nm. The BaTiO3 particles include a BaTiO3 core and a hexadecyltrimethylammonium bromide coating layer.

4. The electrode plate according to claim 3, characterized in that, The concentration gradient of BaTiO3 particles increases from bottom to top in the arched protrusions.

5. The electrode plate according to claim 1, characterized in that, The polymer of the polymer film includes polydimethylsiloxane.

6. A method for preparing an electrode plate according to any one of claims 1 to 5, characterized in that, include: Charged particles are uniformly dispersed in a polymer prepolymer to obtain a dispersion. The dispersion is injected into a microfluidic chip, and a polymer film is prepared by microfluidic 3D printing under an applied DC electric field. The microfluidic chip includes an optical fiber, electrodes, and a dispersion extrusion channel. At least one side surface of the polymer film has a protrusion array. The protrusions are arched in shape, and the concentration gradient of the charged particles increases from bottom to top. An electrode layer is prepared on the side where the protrusion array of the polymer film is located.

7. The preparation method according to claim 6, characterized in that, The polymer is polydimethylsiloxane, the charged particles are BaTiO3 particles with a particle size of 50nm~300nm, the BaTiO3 particles include a BaTiO3 core and a hexadecyltrimethylammonium bromide coating layer, and the ratio of the core diameter to the coating layer thickness is 4~20. The mass ratio of BaTiO3 particles to polydimethylsiloxane prepolymer in the dispersion is 1:3.5~1:4.5, and the DC electric field strength is 150V / mm~250V / mm.

8. The preparation method according to claim 6, characterized in that, The conditions for microcurrent 3D printing include: in-situ UV curing with a light intensity of 30 mW / cm². 2 ~85mW / cm 2 The exposure time is 10s to 30s.

9. A sensor for pressure monitoring, characterized in that, include: An electrode plate, comprising a first electrode plate and a second electrode plate stacked sequentially, wherein the second electrode plate is an electrode plate prepared by the preparation method of the electrode plate according to any one of claims 1 to 5 or the electrode plate according to any one of claims 6 to 8; A sensitive layer is stacked between the first electrode and the second electrode. The sensitive layer includes a gel film. The substrate of the gel film includes a polymer ionic liquid gel. The gel film is doped with nanoparticles. The nanoparticles include a core and a coating layer covering the surface of the core. The core includes Fe3O4, and the coating layer includes polyaniline. Along the thickness direction of the gel film, the elastic modulus of the gel film changes, and the concentration gradient of the nanoparticles also changes. The direction of the elastic modulus gradient change is consistent with the direction of the concentration gradient change. The side of the gel film with a higher elastic modulus is disposed closer to the second electrode.

10. A sensor for monitoring knee joint pressure, characterized in that, It is the pressure monitoring sensor as described in claim 9.

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