Coupling bionic multifunctional micro-fine perception flexible sensor and preparation method thereof

Abstract

The application discloses a coupling bionic multifunctional miniature fine perception flexible sensor and a preparation method thereof, and belongs to the technical field of strain sensors. The coupling bionic multifunctional miniature fine perception flexible sensor comprises, from bottom to top, a lower flexible elastic substrate, an intermediate viscoelastic layer, an intermediate flexible elastic substrate, a proximity-strain resistance layer, a metal lead electrode and an upper flexible elastic film, and the lower end of the lower flexible elastic substrate and the upper end of the upper flexible elastic film are both provided with a packaging protective layer. The proximity-strain resistance layer is in a three-stage snowflake crack structure and is printed by using inkjet printing to form the conductive ink, the three-stage snowflake crack structure comprises six first-stage cracks, each first-stage crack is provided with a plurality of second-stage cracks, each second-stage crack is provided with a plurality of third-stage cracks, and the six first-stage cracks are uniformly distributed in a circle with branch joint points as the center. The sensor integrates a capacitive proximity sensor and a resistance type vibration sensor, can finely perceive a small vibration signal and a proximity signal, and has very rapid response time and recovery time, and good durability and stability.

Description

Technical Field

[0001] This invention belongs to the field of strain sensor technology, specifically relating to a coupled biomimetic multifunctional miniature fine sensing flexible sensor and its fabrication method. Background Technology

[0002] Sensors are used in all aspects of life. Flexible sensors, in particular, are small, lightweight, simple in structure, and flexible and convenient to operate. They can sense minute vibration signals and react accordingly, and are widely used in biology, medicine, engineering, architecture, and other fields, such as intelligent robots, human-computer interaction, wearable electronic devices, electronic skin, human health monitoring, medical diagnosis, and fault detection in machinery and buildings. However, in practical applications, the sensitivity and accuracy of existing flexible sensors are often not guaranteed, and their functions are limited. Efficiently collecting signals from all directions and achieving multi-path signal transmission to obtain ultra-fine sensing remains a challenge. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a coupled biomimetic multifunctional miniature fine sensing flexible sensor and its fabrication method, thereby solving the problems in the prior art.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] The coupled biomimetic multifunctional miniature fine sensing flexible sensor includes, from bottom to top, the following layers: a lower flexible substrate, an intermediate viscoelastic layer, an intermediate flexible substrate, a proximity-strain resistance layer, a metal lead electrode, and an upper flexible film. The lower end of the lower flexible substrate and the upper end of the upper flexible film are both provided with encapsulation and protection layers.

[0006] The proximity-strain resistance layer has a three-level snowflake crack structure and is printed with conductive ink using inkjet printing. The three-level snowflake crack structure includes six primary cracks, each of which has several secondary cracks, and each secondary crack has several tertiary cracks. The six primary cracks are evenly distributed in a circle centered on the intersection of the branches.

[0007] Furthermore, the three-level snowflake crack structure has a length, width, and height of L1, L2, and δ, respectively, satisfying L1=L2≥5δ; and r=0.4L1, where r is the radius of the circular region where the three-level snowflake crack structure is distributed.

[0008] Furthermore, the length of each primary crack is a = r, the crack width is b = 0.02L1, the length ratio of the tertiary cracks is a:0.4a:0.2a; the angle between the primary crack and the secondary crack is 50°, and the angle between the secondary crack and the tertiary crack is 40°.

[0009] Furthermore, the materials of the lower flexible substrate, the middle flexible substrate, and the upper flexible film include one or more of the following: polyimide, polyethylene terephthalate, polydimethylsiloxane, polyurethane, polynaphthalene vinyl ester, polyurethane acrylate, polyethylene, polystyrene, polypropylene, natural rubber, nitrile rubber, thermoplastic vulcanized rubber, silicone, Ecoflex00-10, and Ecoflex00-30.

[0010] Furthermore, the material of the intermediate viscoelastic layer is one or more of PBS, water-soluble substances, latex, and epoxy resin.

[0011] Furthermore, the conductive ink material in the proximity-strain resistance layer is one or more of the following: metal nanoparticle ink, metal oxide ink, organic polymer ink, carbon ink, and semiconductor ink.

[0012] Furthermore, the metal lead electrode is formed by applying paste to both ends of the surface near the strain resistance layer to form an electrode, and then directly bonding the copper wire to the electrode.

[0013] The electrode material is one or more of the following: gold, silver, platinum, copper, brass, copper, copper-tungsten alloy, silver-tungsten alloy, iron, cast iron, steel, graphite, tungsten wire, and molybdenum wire.

[0014] Furthermore, the encapsulation protective layer is made of PET film, which is directly adhered to the surface of the upper flexible film.

[0015] The above-mentioned method for fabricating a coupled biomimetic multifunctional miniature fine sensing flexible sensor includes the following steps:

[0016] S1, mix PDMS and curing agent and vacuum process; apply PDMS mixture onto PET sheet by inkjet printing, and then dry and cure to obtain the lower flexible substrate;

[0017] S2, hydroxyl-terminated polydimethylsiloxane is mixed and reacted with boric acid particles, and heated to obtain a viscous PBS mixture, which is dissolved in n-hexane solution, filtered to obtain PBS, and pressed into a film and attached to the lower flexible substrate to obtain the middle viscoelastic layer;

[0018] S3. Prepare a PDMS film according to the steps in S1, and use oxygen plasma to modify and clean the PDMS film to obtain an intermediate flexible substrate, which is then bonded to the intermediate viscoelastic layer.

[0019] S4, graphene ink is printed onto the intermediate flexible substrate by inkjet printing to form the three-level snowflake crack structure, resulting in a near-strain resistance layer.

[0020] S5, apply silver paste to both ends of the near-strain resistance layer to form silver electrodes, and directly bond copper wire to the silver electrodes;

[0021] S6, mix PDMS and curing agent and vacuum process; select n-butyl acetate to dilute PDMS mixture; inject the diluted PDMS mixture into ink capsule, and then directly inkjet print snowflake crack pattern on the cured near-strain resistance layer, and cure to obtain upper flexible film.

[0022] S7 uses PET film as an encapsulation and protective layer, which is directly attached to the lower end of the lower flexible substrate and the upper end of the upper flexible film to obtain a coupled biomimetic multifunctional miniature fine sensing flexible sensor.

[0023] 10. A wearable smart sensing device, wherein the above-mentioned coupled biomimetic multifunctional micro-fine sensing flexible sensor is provided.

[0024] The beneficial effects of this invention are:

[0025] 1. This invention employs inkjet printing and coating methods to design a multifunctional flexible sensor that couples a biomimetic slit sensor with a snowflake structure. The resulting sensor exhibits high sensitivity, high stability, and high durability. The strain vibration slit sensor is a composite material with a solid structure where the solvent components in the graphene slurry are evaporated after curing, leaving graphite nanoparticles as the main component. When the substrate senses a minute vibration, it causes deformation of the microslit. The strain on the slit leads to changes in the tunneling effect within the graphite particles, resulting in physical changes such as shearing and torsion within the composite matrix and reconstructing the conductive network. Therefore, the strain sensor can achieve high sensitivity by adjusting the parameters of the functional ink. Graphene's unique two-dimensional structure possesses excellent conductivity and stability, enabling it not only to sense vibration signals but also to accurately detect human proximity as a capacitive sensor. It is a miniature sensor that combines resistive and capacitive characteristics.

[0026] 2. The unique snowflake fractal structure of this invention has many branches, which can collect signals from various directions and transport them to the center through multiple paths to achieve signal amplification.

[0027] 3. The intermediate viscoelastic layer in the sensor of the present invention can not only bond the upper and lower PDMS layers well, but also filter out some small energy to eliminate some noise and vibration interference signals, thereby reducing capacitive coupling and signal crosstalk in electronic devices. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the sensor (without packaging) prepared in Embodiment 2 of the present invention;

[0030] Figure 2 Cloud maps showing the finite element simulation results of level one, two, and three crack sensors;

[0031] Figure 3 The cloud map shows the finite element simulation results of the sensor with secondary crack angles of 30°, 40° and 50° respectively.

[0032] Figure 4 The cloud map shows the finite element simulation results of the sensor with three levels of crack angles of 30°, 40° and 50° respectively.

[0033] Figure 5 The cloud map shows the finite element simulation results of the sensor with optimized three-level crack angles of 30°, 40° and 50° respectively.

[0034] Figure 6 This is a schematic diagram of the three-level (II) snowflake crack structure in this invention;

[0035] Figure 7 This is a side view of the sensor in this invention;

[0036] Figure 8 This is an exploded view of the sensor structure in this invention;

[0037] Figure 9 This is a flowchart illustrating the sensor fabrication process in this invention. Detailed Implementation

[0038] 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.

[0039] To confirm the model structure of the flexible sensor of this invention, three-dimensional models of first-, second-, and third-order cracks were established. The lengths of the cracks at different orders were 2 mm, 0.8 mm, and 0.4 mm, respectively. The angles between each crack order were defined as follows: the material of the simulation model had a density of 1.2 kg / m³. 3The Young's modulus is 2.5 MPa, and the Poisson's ratio is 0.35. Loads of magnitude P (P = 20 Pa) are applied in the x and y directions respectively. The simulation results are shown in the contour plot below. Figure 2 As shown, the first three images depict the strain magnitude and distribution of first-, second-, and third-order crack structures in the x-direction (top image) and y-direction (bottom image). It can be seen that the number of cracks determines the magnitude of the model's deformation displacement, and a larger displacement response indicates higher sensor sensitivity. Therefore, the higher the snowflake order, the more sensitive the sensor is to vibrations from any direction. Thus, the sensor of this invention is a three-order snowflake crack structure.

[0040] like Figure 3 and Figure 4 As shown, finite element simulation models with angles of 30°, 40°, and 50° were established between the primary and secondary cracks, and between the secondary and tertiary cracks. Considering the interference problem of different branches, 50° and 40° were selected as the angles between the primary and secondary cracks and between the secondary and tertiary cracks based on the results.

[0041] The sensor of this invention adopts a three-level snowflake crack structure with length, width, and height L1, L2, and δ, respectively, satisfying L1 = L2 ≥ 5δ. The sensor satisfies r = 0.4L1, where r is the radius of the circular region where the three-level snowflake crack structure is distributed. The three-level snowflake crack structure includes six circumferentially evenly distributed primary cracks, each crack having several secondary cracks, and each secondary crack having several tertiary cracks. The six primary cracks are evenly distributed in a circle centered on the intersection of branches. The length of each crack is a = r, and the crack width b satisfies b = 0.02L1. The length ratio of the tertiary cracks is a:0.4a:0.2a. The angle between the primary cracks and the secondary cracks is 50°, and the angle between the secondary cracks and the tertiary cracks is 40°.

[0042] like Figure 1 and Figure 8 As shown, the coupled biomimetic multifunctional miniature fine sensing flexible sensor consists of, from bottom to top: a lower flexible substrate 1, an intermediate viscoelastic layer 2, an intermediate flexible substrate 3, a proximity-strain resistance layer 4, a metal lead electrode 5, and an upper flexible film 6. An encapsulation protective layer 7 is provided at the lower end of the lower flexible substrate 1 and the upper end of the upper flexible film 6.

[0043] The materials chosen for the lower flexible substrate 1, the middle flexible substrate 3, and the upper flexible film 6 are polydimethylsiloxane (PDMS). PDMS is very sensitive to strain, but it has poor wettability and poor adhesion to metals, which can easily lead to electrode detachment. To avoid the tendency of printed ink to shrink and aggregate on the highly hydrophobic PDMS surface, the substrate needs to be further modified, namely oxygen plasma treatment, to enhance the wettability of the substrate.

[0044] The intermediate viscoelastic layer 2 is a polyborosiloxane (PBS) with viscoelastic properties, which can be directly adhered to the underlying flexible substrate 1; it is used to filter out some minute energy to eliminate some noise and vibration interference signals. Furthermore, in some embodiments, the intermediate viscoelastic layer 2 can also be one or more of water-soluble materials, latex, epoxy resin, etc.

[0045] Approach-strain resistance layer 4 Figure 2 The three-level snowflake crack structure shown is formed by curing conductive ink and printing it using inkjet printing. The conductive ink material is one or more of the following: metal nanoparticle ink (including silver nanoparticle ink, gold nanoparticle ink, copper nanoparticle ink, etc.), metal oxide ink (including tin oxide ink, zinc oxide ink, copper oxide ink, etc.), organic polymer ink (such as poly(3,4-ethylenedioxythiophene), polystyrene sulfonate (PEDOT:PSS) and its derivatives, carbon ink (including graphene ink and carbon nanotube ink, etc.), and semiconductor ink (such as indium tin oxide (ITO) ink, etc.).

[0046] The metal lead electrode 5 is formed by coating silver paste on both ends of the surface close to the strain resistance layer 4 to form a silver electrode, and the copper wire is directly bonded to the silver electrode; in addition, in some embodiments, the metal lead electrode 5 can also be one or more of gold, platinum, copper, brass, copper, copper-tungsten alloy, silver-tungsten alloy, iron, cast iron, graphite, steel, tungsten wire, molybdenum wire, etc.

[0047] The upper flexible film 6 is printed onto the near-strain resistance layer 4 by inkjet printing of a mixture of diluted PDMS and curing agent.

[0048] The encapsulation protective layer 7 is made of PET film and is directly pasted onto the surface of the upper flexible film 6.

[0049] The intermediate flexible substrate layer 3, the proximity-strain resistor layer 4, the upper flexible thin film 6, and the metal lead electrode 5 together form a three-layer capacitive proximity sensor, which also constitutes a resistive vibration gap sensor for precise sensing of proximity-strain signals. The proximity-strain resistor layer 4 is made of conductive graphene, which is a type of graphene composed of sp... 2 Graphene is a two-dimensional nanosheet carbon material composed of tightly packed hexagonal carbon atoms arranged in a honeycomb structure. However, graphene slurry lacks resin as its main component, making it prone to particle aggregation and resulting in poor rheological properties and viscosity. Despite this, graphene's unique two-dimensional nanostructure provides excellent electrical conductivity and stability, making it commonly used in flexible electronic devices. The selected conductive carbon slurry needs to be diluted to improve its viscosity and rheological properties before printing can proceed.

[0050] In summary, the ultrasensitive coupling biomimetic micro flexible sensor of the present invention integrates two modes: capacitive proximity sensor and resistive vibration sensor. It can accurately sense minute vibration signals and proximity signals, with rapid response and recovery times, good durability and stability, and excellent performance in all aspects.

[0051] Furthermore, the materials of the lower flexible substrate 1, the middle flexible substrate 3, and the upper flexible film 6 include, but are not limited to, PDMS. In some embodiments, they may also be one or more of the following: polyimide (PI), polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), polyurethane (PU), polynaphthalene vinyl ester (PNE), polyurethane acrylate (PUA), polyimide film (PI), polyethylene (PE), polystyrene (PS), polypropylene (PP), natural rubber, nitrile rubber, thermoplastic vulcanized rubber, silicone, Ecoflex00-10, Ecoflex00-30, etc.

[0052] The fabrication process of the coupled biomimetic multifunctional miniature fine sensing flexible sensor is illustrated below through the following two examples;

[0053] Example 1

[0054] like Figure 9 As shown, the fabrication method of the coupled biomimetic multifunctional miniature fine sensing flexible sensor includes the following steps:

[0055] S1. Mix PDMS and curing agent at a mass ratio of 10:1, stir continuously with a glass rod for 30 seconds, and place in a vacuum drying oven to remove air bubbles for 10 minutes; set up a microelectronic inkjet printer, select a high-viscosity squeegee blade, substrate temperature of 50℃, squeegee height of 33.5mm, squeegee speed of 10mm / s, and working voltage of 55kPa; inject the PDMS mixture into ink capsules, and squeegee a layer of flexible base film onto the PET sheet. After squeegeeing, place in a vacuum drying oven at 70℃ for 60 minutes to cure, which is the lower flexible base 1 with a thickness of 200μm.

[0056] In step S2, hydroxyl-terminated polydimethylsiloxane (H-PDMS, MW4200) and boric acid (BA) particles are mixed in a beaker at a mass ratio of 5:1 and stirred continuously until homogeneous. The mixture is then spin-coated onto a glass slide and gradually heated to 190°C for 1 hour. The viscous PBS mixture is dissolved in a sufficient amount of n-hexane solution, and unreacted boric acid particles are filtered out using filter paper with a pore diameter of 200 nm. The PBS is removed from the beaker, and a small piece is placed between two PET films. A pressure of approximately 0.8 MPa is applied using a pressure device to press the film. After pressing into a film, the PET film can be carefully peeled off due to the poor adhesion between PET and PBS. Since the PDMS material and PBS material have good adhesion properties, the PBS film (intermediate viscoelastic layer 2) can be directly adhered to the lower flexible substrate 1 prepared in step S1, with a thickness of 200 μm.

[0057] S3. Prepare a PDMS film with a thickness of 200 μm according to the steps in S1. Since PDMS has poor adhesion and wettability to metal, it is easy for the electrode to fall off, so surface modification is required. Fix the PDMS film on a glass slide, put the glass slide into a plasma cleaner, and use 200W plasma excitation power to ionize O2 to clean and modify the surface of the PDMS substrate for 3 minutes to obtain the intermediate flexible substrate 3. Then attach the treated intermediate flexible substrate 3 on top of the intermediate viscoelastic layer 2 and cut the overall size.

[0058] S4, the prepared intermediate flexible substrate 3 is fixed on the printing platform of the printer, and then... Figure 2 The three-level snowflake crack structure is imported into the printer software. The dimensions are L1×L2=5mm×5mm, and the end of each branch coincides with the midpoint of the branch above it.

[0059] The graphene aqueous conductive paste (properties: 5wt% graphene micro-flakes, 1-5μm diameter of graphene flakes, 0.5wt% dispersant, 94.5wt% water) was placed in a glass bottle and subjected to an ultrasonic bath treatment at 30℃ for 20 minutes to ensure uniform solute in the functional ink and prevent graphene particles from agglomerating into large-diameter particles and clogging the printhead during long-term standing.

[0060] Graphene ink is injected into the ink cartridge capsule. During the injection process, the ink needs to be slowly filtered through a 0.22μm nylon filter to avoid the formation of small air bubbles. After installing the ink cartridge, the printer is calibrated. The printhead temperature of the microelectronic inkjet printer is set to 25℃, the substrate temperature to 50℃, the droplet pitch to 20μm, the working voltage of the piezoelectric ceramic sheet to 55kPa, the line width to 100μm, the printing speed to 1mm / s, and the printing height to 23mm.

[0061] First, clean and test the printer. After testing, select four evenly spaced inkjet nozzles for multi-layer printing. Print 10 layers, then remove and cure once, for a total of 60 layers. Before curing, use high-temperature tape to fix the sensor substrate to prevent thermal stress from causing it to warp. Cure at 70℃ for 30 minutes in a vacuum drying oven. After curing, when placing the substrate again, camera calibration is required to align the nozzle center with the camera center, ensuring the same position as the previous print before proceeding with the next print. The final printed product is... Figure 2 The near-strain resistance layer 4 of the three-level snowflake crack structure shown has a thickness of 100 μm.

[0062] S5, apply silver paste to both ends of the surface of the near-strain resistance layer 4 to form silver electrodes, and then directly bond copper wire to the silver electrodes.

[0063] S6. Mix PDMS and curing agent at a mass ratio of 10:1, stir continuously with a glass rod for 30 seconds, and place in a vacuum drying oven to remove air bubbles for 10 minutes; select high-boiling-point n-butyl acetate as diluent, mix and dilute the PDMS precursor mixture containing curing agent with diluent at a volume ratio of 1:3, and stir for 10 minutes.

[0064] The diluted PDMS mixture was injected into the ink capsule, and during the injection process, the mixture was slowly filtered through a 0.22μm nylon filter. The printer nozzle temperature was set to room temperature, the substrate temperature to 5℃, the droplet pitch to 20μm, the working voltage of the piezoelectric ceramic sheet to 65kPa, the linewidth to 120μm, the printing speed to 1mm / s, and the printing height to 21.5mm. Then, a snowflake crack pattern was directly inkjet printed onto the cured proximity-strain resistance layer 4, for a total of 10 layers. After printing, the layer was cured at 70℃ for 60 minutes in a vacuum drying oven, thus completing the printing of the upper flexible film 6 with a thickness of 100μm.

[0065] S7, using PET film as the encapsulation protective layer 7, is directly adhered to the lower end of the lower flexible substrate 1 and the upper end of the upper flexible film 6; the overall sensor thickness is 1mm, such as... Figure 7 As shown.

[0066] Example 2

[0067] The difference between this embodiment and Embodiment 1 is that the three-level snowflake crack structure (the printing shape of the near-strain resistance layer 4 in S4) is optimized, that is, the following is adopted: Figure 2 In the third level (II), two third-level structures were repeatedly set. The simulation structure shows that this structure has a higher displacement response than the other three, and is more sensitive and stable in signal sensing and collection.

[0068] The angle between the primary and secondary cracks in the optimized crack structure remains 50°. According to... Figure 5 Comparing the different angles between level 3 and level 2 cracks, and considering the need to avoid stress concentration at the thinner edges, 40° was chosen as the final angle. The planar dimensions of the snowflake structure used in this embodiment are as follows: Figure 6 As shown.

[0069] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0070] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A coupled biomimetic multifunctional miniature fine sensing flexible sensor, characterized in that, The structure consists of, from bottom to top, the following layers: a lower flexible substrate (1), an intermediate viscoelastic layer (2), an intermediate flexible substrate (3), a proximity-strain resistance layer (4), a metal lead electrode (5), and an upper flexible film (6). A protective encapsulation layer (7) is provided at the lower end of the lower flexible substrate (1) and the upper end of the upper flexible film (6). The proximity-strain resistance layer (4) has a three-level snowflake crack structure and is printed with conductive ink by inkjet printing. The three-level snowflake crack structure includes six primary cracks, each primary crack has several secondary cracks, each secondary crack has several tertiary cracks, and the six primary cracks are evenly distributed in a circle with the intersection of branches as the center. The three-level snowflake crack structure has a length, width, and height of [missing information]. ,satisfy And r = 0.4 , where r is the radius of the circular region where the third-order snowflake crack structure is distributed; The length of each primary crack is a=r, and the crack width is b=0.

02. The length ratio of the three-level cracks is a:0.4a:0.2a; the angle between the first-level crack and the second-level crack is 50°, and the angle between the second-level crack and the third-level crack is 40°.

2. The coupled biomimetic multifunctional miniature fine sensing flexible sensor according to claim 1, characterized in that, The materials of the lower flexible substrate (1), the middle flexible substrate (3) and the upper flexible film (6) include one or more of the following: polyimide, polyethylene terephthalate, polydimethylsiloxane, polyurethane, polynaphthalene vinyl ester, polyurethane acrylate, polyethylene, polystyrene, polypropylene, natural rubber, nitrile rubber, thermoplastic vulcanized rubber, silicone, Ecoflex00-10, and Ecoflex00-30.

3. The coupled biomimetic multifunctional miniature fine sensing flexible sensor according to claim 1, characterized in that, The material of the intermediate viscoelastic layer (2) is one or more of PBS, water-soluble substances, latex, and epoxy resin.

4. The coupled biomimetic multifunctional miniature fine sensing flexible sensor according to claim 1, characterized in that, The conductive ink material in the proximity-strain resistance layer (4) is one or more of the following: metal nanoparticle ink, metal oxide ink, organic polymer ink, carbon ink, and semiconductor ink.

5. The coupled biomimetic multifunctional miniature fine sensing flexible sensor according to claim 1, characterized in that, The metal lead electrode (5) is formed by coating the two ends of the surface of the near-strain resistance layer (4) with paste to form the electrode, and the copper wire is directly bonded to the electrode; The electrode material is one or more of the following: gold, silver, platinum, copper, brass, copper, copper-tungsten alloy, silver-tungsten alloy, iron, cast iron, steel, graphite, tungsten wire, and molybdenum wire.

6. The coupled biomimetic multifunctional miniature fine sensing flexible sensor according to claim 1, characterized in that, The encapsulation protective layer (7) is made of PET film and is directly pasted onto the surface of the upper flexible film (6).

7. The method for fabricating the coupled biomimetic multifunctional miniature fine sensing flexible sensor according to any one of claims 1-6, characterized in that, Includes the following steps: S1, PDMS and curing agent are mixed and vacuumed; the PDMS mixture is coated onto PET sheet by inkjet printing, and then dried and cured to obtain the lower flexible substrate (1). S2, hydroxyl-terminated polydimethylsiloxane is mixed and reacted with boric acid particles, and heated to obtain a viscous PBS mixture, which is dissolved in n-hexane solution, filtered to obtain PBS and pressed into a film and attached to the lower flexible substrate (1) to obtain the middle viscoelastic layer (2). S3, prepare a PDMS film according to the steps of S1, and use oxygen plasma to modify and clean the PDMS film to obtain an intermediate flexible substrate (3), and attach it to the intermediate viscoelastic layer (2); S4, graphene ink is printed on the intermediate flexible substrate (3) by inkjet printing to form the three-level snowflake crack structure and obtain a near-strain resistance layer (4). S5, apply silver paste to both ends of the surface of the near-strain resistance layer (4) to form silver electrodes, and directly bond copper wire to the silver electrodes to obtain metal lead electrodes (5). S6, mix PDMS and curing agent and vacuum process; select n-butyl acetate to dilute PDMS mixture; inject the diluted PDMS mixture into ink sac, and then directly inkjet print snowflake crack pattern on the cured near-strain resistance layer (4), and cure to obtain upper flexible film (6). S7. Using PET film as a protective encapsulation layer (7), it is directly attached to the lower end of the lower flexible substrate (1) and the upper end of the upper flexible film (6) to obtain a coupled biomimetic multifunctional micro-fine sensing flexible sensor.

8. A wearable smart sensing device, characterized in that, It is equipped with the coupled biomimetic multifunctional miniature fine sensing flexible sensor as described in any one of claims 1-6.

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