Hollow bulge and honeycomb structure coupled flexible pressure sensor and preparation method thereof

Abstract

The invention relates to the technical field of preparation of flexible pressure sensors, and discloses a hollow projection and honeycomb structure coupled flexible pressure sensor and a preparation method thereof. The flexible pressure sensor is prepared by coating a mixed solution of liquid metal, a conductive material and an elastomer composite material on a mold of the flexible pressure sensor; and curing to prepare the composite material. Wherein the front side of the flexible pressure sensor is of a honeycomb structure with a plurality of circular holes arranged in an array, the back side of the flexible pressure sensor is of a plurality of hollow protrusions arranged in an array, and the honeycomb structure corresponds to the hollow protrusions in a one-to-one mode. And the sensitivity and durability of the flexible pressure sensor are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of flexible pressure sensors, and in particular relates to a flexible pressure sensor coupled with a hollow protrusion and a honeycomb structure and a preparation method thereof. Background Art

[0002] In recent years, the research on flexible pressure sensors has become a hot field in the intersection of multiple disciplines such as materials science and electronic engineering. Structurally, traditional pressure sensors mainly adopt a planar structure or a design with a solid protrusion structure. These structures have certain limitations in terms of sensitivity and durability. When subjected to pressure, the planar structure sensor lacks an effective deformation concentration area, resulting in low sensitivity and difficulty in accurately sensing tiny pressure changes. Although the sensor with a solid protrusion structure has improved the sensitivity to a certain extent, during the pressing and stretching process, the solid protrusion is prone to stress concentration, resulting in microstructural fracture, which in turn causes signal drift and other problems, limiting its use in application scenarios that require frequent pressing, deformation, and bending.

[0003] Traditional flexible pressure sensors typically use a single conductive material, such as metal film or conductive polymer. These materials have limitations in terms of conductivity and mechanical properties. For example, metal film is prone to fracture when subjected to high pressure or stretching, causing sensor failure. While conductive polymers offer good flexibility, their relatively low conductivity affects the sensor's response speed and accuracy. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a flexible pressure sensor coupled with a hollow protrusion and a honeycomb structure and a preparation method. Through the coupling design of the hollow protrusion structure of the flexible pressure sensor and the circular hole honeycomb structure, the sensitivity and durability of the flexible pressure sensor are improved.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A flexible pressure sensor with a hollow protrusion coupled to a honeycomb structure, the flexible pressure sensor being prepared by coating a mixed solution of liquid metal, a conductive material, and an elastomer composite material on a mold of the flexible pressure sensor and curing the mixed solution;

[0007] The front side of the flexible pressure sensor is a honeycomb structure with multiple circular holes arranged in an array, and the back side is a plurality of hollow protrusions arranged in an array, and the honeycomb structure corresponds to the hollow protrusions one by one.

[0008] Furthermore, the elastomer composite material includes one or more of PDMS and silicone.

[0009] Furthermore, the conductive material includes one or more of carbon nanotubes, graphene, carbon nanofibers, boron nitride nanotubes or conductive polymers.

[0010] Furthermore, the mold of the flexible pressure sensor includes a substrate and a plurality of arc-shaped protrusions arranged in an array on the substrate, and the shape of the arc-shaped protrusions is consistent with the shape of the hollow protrusions.

[0011] Furthermore, when the flexible pressure sensor is in a relaxed state, the continuous conductive network composed of the liquid metal and the conductive material provides a resistance path; when pressure is applied to the flexible pressure sensor, the elastic matrix formed by the elastomer composite material is deformed, and the distance between the liquid metal and the conductive material in the continuous conductive network increases. At the same time, the insulating elastic matrix fills the gap between the liquid metal and the conductive material, blocking part of the electron migration path.

[0012] The present invention also provides a method for preparing a flexible pressure sensor having a hollow protrusion coupled with a honeycomb structure, comprising the following steps:

[0013] S1. Prepare a mold for a flexible pressure sensor; wherein the mold comprises: a substrate and a plurality of arc-shaped protrusions arranged in an array on the substrate;

[0014] S2. Pour the conductive material powder into the stock solution of the elastomer composite material, and stir to mix them evenly to obtain a first mixed liquid;

[0015] S3, adding a curing agent of the liquid metal and elastomer composite material to the first mixed liquid, and stirring under an ultrasonic environment to mix them uniformly to obtain a second mixed liquid;

[0016] S4, pouring the second mixed liquid onto the multiple arc-shaped protrusions of the mold, repeatedly brushing it evenly, eliminating bubbles, and then placing it in a drying oven for curing to obtain a mixed solid;

[0017] S5. Removing the mixed solid from the mold to obtain a flexible pressure sensor with a hollow protrusion coupled to a honeycomb structure.

[0018] Furthermore, in said S1, the specific method for preparing the mold of the flexible pressure sensor is to print out a positive mold sample corresponding to the hollow protrusion by using the fused deposition modeling technology.

[0019] Furthermore, in said S4, the product is placed in a drying oven for curing; wherein the curing temperature is 65° C. and the curing time is 30 minutes.

[0020] Furthermore, in S4, the second mixed liquid is poured onto the plurality of arc-shaped protrusions of the mold and repeatedly applied evenly, specifically: the thickness of the application is lower than the thickness of the arc-shaped protrusions.

[0021] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: The present invention significantly improves the sensitivity and durability of the flexible pressure sensor through the coupling design of the hollow protrusion structure and the circular hole honeycomb structure. The hollow protrusion structure enables the sensor to undergo significant deformation when subjected to pressure, thereby improving sensitivity; the circular hole honeycomb structure disperses stress, avoids local fracture or permanent deformation of the material, and enhances the elastic deformation capacity, fatigue resistance and cyclic stability of the flexible pressure sensor. By combining liquid metal and conductive material, the high conductivity of liquid metal and the nanoscale conductive network characteristics of the conductive material are fully utilized to achieve the dynamic formation of a resistance path, thereby improving the conductivity and pressure response characteristics of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0023] The flexible pressure sensor coupled with a hollow protrusion and a honeycomb structure and its preparation method of the present invention are further described below with reference to the accompanying drawings;

[0024] Figure 1 This is a schematic flow chart of a method for preparing a flexible pressure sensor provided by the present invention;

[0025] Figure 2 This is a schematic diagram of the position distribution of liquid metal and conductive material in the flexible pressure sensor provided by the present invention before pressing;

[0026] Figure 3 This is a schematic diagram of the positions of liquid metal and conductive material after the flexible pressure sensor provided by the present invention is pressed;

[0027] Figure 4 This is a schematic diagram of the overall structure of a mold for producing a flexible pressure sensor by reverse molding provided by the present invention;

[0028] Figure 5 This is a schematic structural diagram of one side of the flexible pressure sensor provided by the present invention that has a honeycomb structure;

[0029] Figure 6 This is a structural schematic diagram of one side of an arc-shaped protrusion in an array structure in the flexible pressure sensor provided by the present invention;

[0030] Figure 7 2 is a schematic structural diagram of the flexible pressure sensor provided by the present invention; wherein (a) is a schematic side structural diagram of the flexible pressure sensor, and (b) is a schematic cross-sectional structural diagram of the flexible pressure sensor. DETAILED DESCRIPTION

[0031] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0032] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below with reference to the accompanying drawings.

[0033] Example 1

[0034] The present invention provides a flexible pressure sensor coupled with a hollow protrusion and a honeycomb structure. The flexible pressure sensor is prepared by coating a mixed solution of liquid metal, conductive material and elastomer composite material on a mold of the flexible pressure sensor and curing the mixed solution.

[0035] The front of the flexible pressure sensor is a honeycomb structure with multiple circular holes arranged in an array, and the back is a plurality of hollow protrusions arranged in an array, and the honeycomb structure corresponds to the hollow protrusions one by one, such as Figure 7 (a) and Figure 7 As shown in (b).

[0036] The elastomer composite material includes: one or more of PDMS and silicone.

[0037] The conductive material includes one or more of carbon nanotubes, graphene, carbon nanofibers, boron nitride nanotubes or conductive polymers.

[0038] The mold of the flexible pressure sensor includes a substrate and a plurality of arc-shaped protrusions arranged in an array on the substrate, and the shape of the arc-shaped protrusions is consistent with the shape of the hollow protrusions, such as Figure 4-6 shown.

[0039] When the flexible pressure sensor is in a relaxed state, the continuous conductive network composed of the liquid metal and the conductive material provides a resistance path; when pressure is applied to the flexible pressure sensor, the elastic matrix formed by the elastomer composite material is deformed, and the distance between the liquid metal and the conductive material in the continuous conductive network increases. At the same time, the insulating elastic matrix fills the gap between the liquid metal and the conductive material, blocking part of the electron migration path.

[0040] In this embodiment, the liquid metal has metallic-level conductivity and fluidity, which complements the nanoscale conductive network of carbon nanotubes (CNTs). When the material is compressed and deformed, the flow characteristics of the liquid metal can dynamically fill the gaps in the carbon nanotube (CNT) network, forming a continuous resistance path, such as Figure 3 As shown. Carbon nanotubes (CNTs) have excellent electrical conductivity and mechanical strength, and work synergistically with liquid metal to enhance the conductivity and stability of the sensor. Combining these two with a flexible substrate (PDMS) can form a flexible sensor with excellent deformation properties, good repeatability, short delay time, and repeatable pressing, bending and folding effects. These sensors can be widely used in wearable devices for real-time monitoring of human physiological signals, including finger bending, elbow bending, and knee bending. Due to their excellent stress-strain response capabilities, they can also be used as tiny pressure detection devices for applications in healthcare, human-computer interaction, and other fields.

[0041] Example 2

[0042] The present invention also provides a method for preparing a flexible pressure sensor having a hollow protrusion coupled with a honeycomb structure, such as Figure 1 As shown, the following steps are included:

[0043] S1. Prepare a mold for a flexible pressure sensor; wherein the mold comprises: a substrate and a plurality of arc-shaped protrusions arranged in an array on the substrate;

[0044] S2. Pour the conductive material powder into the stock solution of the elastomer composite material, and stir to mix them evenly to obtain a first mixed liquid;

[0045] S3, adding a curing agent of the liquid metal and elastomer composite material to the first mixed liquid, and stirring under an ultrasonic environment to mix them uniformly to obtain a second mixed liquid;

[0046] S4, pouring the second mixed liquid onto the multiple arc-shaped protrusions of the mold, repeatedly brushing it evenly, eliminating bubbles, and then placing it in a drying oven for curing to obtain a mixed solid;

[0047] S5. Removing the mixed solid from the mold to obtain a flexible pressure sensor with a hollow protrusion coupled to a honeycomb structure.

[0048] In S1, the specific method for preparing the mold of the flexible pressure sensor is to print out a positive mold sample corresponding to the hollow protrusion by using the fused deposition modeling technology.

[0049] In S4, the product is placed in a drying oven for curing; wherein the curing temperature is 65° C. and the curing time is 30 minutes.

[0050] In S4, the second mixed liquid is poured onto the plurality of arc-shaped protrusions of the mold and repeatedly brushed evenly. Specifically, the brushing thickness is lower than the thickness of the arc-shaped protrusions.

[0051] In this embodiment, the method for preparing the flexible pressure sensor is specifically as follows:

[0052] (a) Use model design software to design a mold model and construct a cylindrical array with a spherical top, where the cylindrical part serves as the positive mold of the sensor base and the hemispherical part on the top serves as the positive mold of the protrusion structure, as shown in Figure 2. Figure 4 As shown in Figure 1, this structural design allows the protrusion of the sensor to deform significantly when subjected to pressure, thereby improving the sensor's sensitivity. The circular honeycomb structure disperses stress and enhances elastic deformation capacity, preventing stress concentration from causing localized fracture or permanent deformation of the material.

[0053] (b) Through fused deposition model 3D printing (FFF), photolithography or ink direct writing 3D printing (DIW), a positive mold sample corresponding to a hollow structure coupled with a circular honeycomb structure is printed, which can produce complex three-dimensional structures and provide a precise mold for the subsequent casting of functional materials. The preparation process based on 3D printing achieves efficient mold preparation and reduces costs, providing a solution that is both economical and reliable for wearable devices and IoT terminals.

[0054] (c) Pour CNT powder (conductive material) into PDMS (elastic matrix) stock solution and mechanically stir and mix. After homogenization, add liquid metal (EGaIn) and PDMS (elastic matrix) curing agent and stir and mix in an ultrasonic cleaner.

[0055] (d) The mixed functional material is then poured into the 3D-printed mold and repeatedly applied with a brush (so that the functional material can cover the original cylinder, so that the final sensor can form a honeycomb structure while also having a concentric hollow protrusion structure corresponding to the circular hole).

[0056] (e) The mold coated with the functional material is placed steadily inside a vacuum pump to eliminate air bubbles, and then placed in an oven for curing at 65°C for 30 minutes. During the curing process, the functional material forms a stable structure in the mold, ensuring the performance of the sensor.

[0057] (f) Finally, use tweezers to remove the cured sensing structure from the mold.

[0058] Among them, Figure 5 As shown, the top of the hollow raised structure of the mold is a curved surface or a circle, as shown in FIG. Figure 6 He Ru Figure 7As shown, the mold bottom is hollow. This design allows the sensor's protruding portion to deform significantly when subjected to pressure. This deformation of the hollow portion significantly amplifies the pressure signal, thereby improving the sensor's sensitivity. The sensor's interior utilizes a circular honeycomb structure, similar to the hexagonal arrangement of honeycombs. This structure disperses externally applied stress, preventing stress concentration that could lead to localized fracture or permanent deformation in the material, while also enhancing the sensor's elastic deformation capacity and fatigue resistance.

[0059] The positive mold sample corresponding to the hollow structure is printed using the fused deposition modeling (FFF) technology, achieving efficient mold preparation, with each piece taking less than 30 minutes.

[0060] During sensor fabrication, a brush is used to repeatedly apply the viscous functional material to completely cover the mold surface, forming a honeycomb structure and hollow protrusions. This simplifies the fabrication process and ensures material uniformity and structural integrity. The combination of fused deposition modeling (FFF) technology and repeated brush application simplifies the fabrication process, reduces costs, and improves efficiency. Compared to traditional manufacturing processes, this method offers greater flexibility and enables the rapid design and fabrication of complex structures.

[0061] In summary, compared with the prior art, the technology in this embodiment also has the following technical effects:

[0062] 1) Enhanced durability and stability. The circular honeycomb structure effectively disperses stress, preventing localized fracture or permanent deformation of the material due to stress concentration, thereby significantly improving the sensor's elastic deformation capacity, fatigue resistance, and cyclic stability. Compared with existing technologies, this invention demonstrates greater stability and durability in applications involving frequent pressing, stretching, and bending, reducing signal drift.

[0063] 2) Optimized material properties. This invention utilizes a combination of liquid metal and carbon nanotubes (CNTs), leveraging the high conductivity and fluidity of liquid metal and the nanoscale conductive network properties of CNTs. This material combination maintains connectivity of the conductive network even when deformed by high pressure, significantly improving the sensor's conductivity and pressure response, overcoming the conductivity and mechanical performance limitations of traditional single conductive materials.

[0064] 3) Efficient and economical manufacturing process: This invention utilizes 3D printing technology and a brush-based coating process, simplifying the manufacturing process, reducing costs, and improving efficiency. Compared to traditional manufacturing processes, this method is more flexible and can rapidly design and manufacture complex structures, providing an economical and reliable solution for wearable devices and IoT terminals.

[0065] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A flexible pressure sensor coupled with a hollow protrusion and a honeycomb structure, characterized in that: The flexible pressure sensor is prepared by coating a mixed solution of liquid metal, conductive material and elastomer composite material on a mold of the flexible pressure sensor and curing the mixed solution; The front side of the flexible pressure sensor is a honeycomb structure with multiple circular holes arranged in an array, and the back side is a plurality of hollow protrusions arranged in an array, and the honeycomb structure corresponds to the hollow protrusions one by one.

2. The flexible pressure sensor coupled with a hollow protrusion and a honeycomb structure according to claim 1, characterized in that: The elastomer composite material includes: one or more of PDMS and silicone.

3. The flexible pressure sensor coupled with a hollow protrusion and a honeycomb structure according to claim 1, characterized in that: The conductive material includes one or more of carbon nanotubes, graphene, carbon nanofibers, boron nitride nanotubes or conductive polymers.

4. The flexible pressure sensor coupled with a hollow protrusion and a honeycomb structure according to claim 1, characterized in that: The mold of the flexible pressure sensor includes a substrate and a plurality of arc-shaped protrusions arranged in an array on the substrate, and the shape of the arc-shaped protrusions is consistent with the shape of the hollow protrusions.

5. The flexible pressure sensor coupled with a hollow protrusion and a honeycomb structure according to claim 1, characterized in that: When the flexible pressure sensor is in a relaxed state, the continuous conductive network composed of the liquid metal and the conductive material provides a resistance path; when pressure is applied to the flexible pressure sensor, the elastic matrix formed by the elastomer composite material is deformed, and the distance between the liquid metal and the conductive material in the continuous conductive network increases. At the same time, the insulating elastic matrix fills the gap between the liquid metal and the conductive material, blocking part of the electron migration path.

6. A method for preparing a flexible pressure sensor with a hollow protrusion coupled to a honeycomb structure, which is used to prepare the flexible pressure sensor with a hollow protrusion coupled to a honeycomb structure as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1. preparing a mold for a flexible pressure sensor; The mold includes: a substrate and a plurality of arc-shaped protrusions arranged in an array on the substrate; S2. Pour the conductive material powder into the stock solution of the elastomer composite material, and stir to mix them evenly to obtain a first mixed liquid; S3, adding a curing agent of the liquid metal and elastomer composite material to the first mixed liquid, and stirring under an ultrasonic environment to mix them uniformly to obtain a second mixed liquid; S4, pouring the second mixed liquid onto the multiple arc-shaped protrusions of the mold, repeatedly brushing it evenly, eliminating bubbles, and then placing it in a drying oven for curing to obtain a mixed solid; S5. Removing the mixed solid from the mold to obtain a flexible pressure sensor with a hollow protrusion coupled to a honeycomb structure.

7. The method for preparing a flexible pressure sensor with a hollow protrusion coupled with a honeycomb structure according to claim 6, characterized in that: In S1, the specific method for preparing the mold of the flexible pressure sensor is to print out a positive mold sample corresponding to the hollow protrusion by using the fused deposition modeling technology.

8. The method for preparing a flexible pressure sensor with a hollow protrusion coupled with a honeycomb structure according to claim 6, characterized in that: In S4, the product is placed in a drying oven for curing; The curing temperature is 65° C. and the curing time is 30 minutes.

9. The method for preparing a flexible pressure sensor with a hollow protrusion coupled with a honeycomb structure according to claim 6, wherein: In S4, the second mixed liquid is poured onto the plurality of arc-shaped protrusions of the mold and repeatedly brushed evenly. Specifically, the brushing thickness is lower than the thickness of the arc-shaped protrusions.

Images