Multifunctional flexible pressure sensor with microstructure and preparation method thereof

Abstract

The invention provides a multifunctional flexible pressure sensor with a microstructure and a preparation method thereof, and the preparation method comprises the steps: adding a carbon nanotube and Mxene into polydimethylsiloxane, and carrying out the magnetic stirring to form a mixed solution; adding a curing agent and xylene into the mixed solution, and stirring to obtain printing ink; the printing ink is transferred into a dispensing needle cylinder of a 3D printer, 3D printing is conducted according to a set printing model and a printing structure, a sensor base body corresponding to the printing model is obtained, the sensor base body is provided with microstructures corresponding to the printing structure, and the microstructures at least comprise a micro-cone structure, a micro-column structure and a micro-hemisphere structure; the sensor substrate is moved into a concentrated sulfuric acid solution to be soaked, acid treatment is carried out, so that the surface of the sensor substrate has a micro-nano structure, and the multifunctional flexible pressure sensor is obtained. According to the scheme, a simple preparation method of the multifunctional sensor is provided, the contact area between the sensor and external pressure is also increased by the microstructure, and the pressure change can be sensed more sensitively.

Description

Technical Field

[0001] The present application relates to the technical field of flexible wearable health electronic devices, and in particular to a multifunctional flexible pressure sensor with a microstructure and a preparation method thereof. Background Art

[0002] In the current field of pressure sensors, traditional pressure sensors have many limitations. On the one hand, their flexibility is poor and they are difficult to adapt to complex curved surfaces or dynamically deformed environments. In application scenarios such as wearable devices and human-computer interactions that require close fit with the human body or dynamic objects, they cannot achieve good performance. On the other hand, in certain complex environments, performance degradation is often prone to occur, and their continuous and stable operation cannot be guaranteed, and the demand for multifunctional integration of sensors cannot be met. At the same time, the sensitivity of existing sensors needs to be improved, and it is difficult to accurately sense small pressure changes. In addition, in terms of preparation technology, if the sensor prepared by conventional methods is to be multifunctional, it is usually sprayed with a super-hydrophobic solution on the pressure sensor to obtain a super-hydrophobic surface, and a layered method is used to design an electromagnetic shielding layer to prevent electromagnetic interference from affecting the sensor. The above preparation process is cumbersome and it is extremely easy to cause mutual influence between the steps. Summary of the invention

[0003] In view of the above-mentioned defects or deficiencies in the prior art, the present application aims to provide a multifunctional flexible pressure sensor with a microstructure and a preparation method thereof, so as to obtain a multifunctional sensor in a simple preparation manner.

[0004] In a first aspect, the present application proposes a method for preparing a multifunctional flexible pressure sensor with a microstructure, comprising: Add carbon nanotubes and Mxene into polydimethylsiloxane and stir magnetically to form a mixed solution; Adding a curing agent and xylene into the mixed solution, and stirring to obtain a printing ink; The printing ink is transferred into a dispensing syringe of a 3D printer, and 3D printing is performed according to a set printing model and a printing structure to obtain a sensor substrate corresponding to the printing model, wherein the sensor substrate has a microstructure corresponding to the printing structure, and the microstructure includes at least a microcone structure, a microcolumn structure, and a microhemispherical structure; The sensor substrate is moved to a concentrated sulfuric acid solution for immersion, and an acid treatment is performed to make the surface of the sensor substrate have a micro-nano structure, so as to obtain a multifunctional flexible pressure sensor.

[0005] According to the technical solution provided in the embodiment of the present application, after the sensor substrate is moved to a concentrated sulfuric acid solution for immersion and acid treatment is performed so that the surface of the sensor substrate has a micro-nano structure, the following steps are also included: The sensor substrate with the micro-nano structure on the surface is taken out from the concentrated sulfuric acid solution, the residual concentrated sulfuric acid on the surface is washed with clean water, and then the sensor substrate is placed in a drying box for drying.

[0006] According to the technical solution provided in the embodiment of the present application, the printing model includes at least a cuboid, a cylinder, a prism and a pyramid.

[0007] According to the technical solution provided in the embodiment of the present application, the mass ratio of carbon nanotubes, Mxene and polydimethylsiloxane in the mixed solution is 4:12:84.

[0008] According to the technical solution provided in the embodiment of the present application, the inner diameter of the dispensing syringe of the 3D printer is 290 μm, the printing speed is 1 mm / s-20 mm / s, and the applied pressure of the vacuum pump is 50 psi-100 psi.

[0009] According to the technical solution provided in the embodiment of the present application, the concentration of the concentrated sulfuric acid solution is 90%-98%, and the immersion time of the sensor substrate in the concentrated sulfuric acid solution is 1-10 minutes.

[0010] According to the technical solution provided in the embodiment of the present application, the setting temperature of the drying box is 60°C-120°C.

[0011] According to the technical solution provided in the embodiment of the present application, rinse with clean water for 20-60 minutes.

[0012] In the second aspect, the present application proposes a multifunctional flexible pressure sensor with a microstructure, which is prepared by the preparation method of the multifunctional flexible pressure sensor with a microstructure as described above; it includes a sensor substrate, and the sensor substrate is obtained by printing ink through 3D printing technology; the printing ink is formed by adding carbon nanotubes and Mxene to polydimethylsiloxane, and then adding a curing agent and xylene, and stirring; the sensor substrate has a microstructure formed by 3D printing technology, and the surface of the sensor substrate also has a micro-nano structure formed by acidification treatment.

[0013] According to the technical solution provided in the embodiment of the present application, the thickness of the multifunctional flexible pressure sensor is 1mm-100mm.

[0014] Compared with the prior art, the beneficial effect of the present application is that by adding carbon nanotubes and Mxene to polydimethylsiloxane, the prepared pressure sensor has multiple functions. The excellent conductivity and mechanical properties of carbon nanotubes, as well as the unique electrical and chemical properties of Mxene, give the sensor the ability to respond to other environmental factors such as temperature and humidity in addition to pressure perception, thus realizing multifunctional integration. The sensor substrate has microstructures such as microcone structure, microcolumn structure, and microhemispherical structure, which greatly increases the contact area and stress concentration effect between the sensor and the external pressure. When subjected to pressure, these microstructures can more keenly perceive pressure changes and convert them into changes in electrical signals, thereby significantly improving the sensitivity of the sensor and being able to accurately detect tiny pressure fluctuations. Based on polydimethylsiloxane, it has good flexibility itself, so that the prepared sensor can adapt to various complex shapes and dynamic deformations, and has broad application prospects in the fields of wearable devices, biomedical monitoring, etc., and can achieve close fit with human skin or other flexible objects without affecting the wearer's activities. The sensor substrate is moved to a concentrated sulfuric acid solution and soaked for acid treatment to form a micro-nano structure on the surface. This micro-nano structure further increases the specific surface area of ​​the sensor and improves its surface properties, which not only helps to improve the sensitivity and stability of the sensor, but also may enhance its adsorption or reaction ability to specific substances, thereby expanding the application range of the sensor. The use of 3D printing technology realizes the multifunctional integration of sensors on the basis of a simple preparation process, improves the stability of the sensor in complex environments, and greatly shortens the R&D cycle and production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flowchart of the steps of a method for preparing a multifunctional flexible pressure sensor with a microstructure provided in an embodiment of the present application; Figure 2 A schematic structural diagram of a multifunctional flexible pressure sensor with a microstructure (the microstructure is a micro-cone structure) provided in an embodiment of the present application.

[0016] The text annotations in the figure represent: 1. Multifunctional flexible pressure sensor; 11. Microstructure. DETAILED DESCRIPTION

[0017] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] Example 1 As mentioned in the background technology, in view of the problems in the prior art, the present application proposes a method for preparing a multifunctional flexible pressure sensor with a microstructure, comprising: S1, adding carbon nanotubes and Mxene to polydimethylsiloxane, and stirring by magnetic force to form a mixed solution; S2, adding a curing agent and xylene to the mixed solution, and stirring to obtain a printing ink; S3, transferring the printing ink into a dispensing syringe of a 3D printer, performing 3D printing according to a set printing model and printing structure, and obtaining a sensor substrate corresponding to the printing model, wherein the sensor substrate has a microstructure 11 corresponding to the printing structure, and the microstructure 11 includes at least a microcone structure, a microcolumn structure, and a microhemispherical structure; Among them, the cuboid is the most commonly used; the printing model is the external overall shape of the finished product to be printed, the printing structure is the internal shape, and the printing model and structure are designed by three-dimensional design software.

[0020] S4, moving the sensor substrate to a concentrated sulfuric acid solution for immersion, and performing an acid treatment so that the surface of the sensor substrate has a micro-nano structure, so as to obtain a multifunctional flexible pressure sensor 1.

[0021] In a preferred embodiment, after the sensor substrate is moved to a concentrated sulfuric acid solution for immersion and subjected to acid treatment so that the surface of the sensor substrate has a micro-nano structure, the following steps are further included: The sensor substrate with the micro-nano structure on the surface is taken out from the concentrated sulfuric acid solution, the residual concentrated sulfuric acid on the surface is washed with clean water, and then the sensor substrate is placed in a drying box for drying.

[0022] In a preferred embodiment, the printing model includes at least a cuboid, a cylinder, a prism and a pyramid.

[0023] In a preferred embodiment, the mass ratio of carbon nanotubes, Mxene and polydimethylsiloxane in the mixed solution is 4:12:84.

[0024] In a preferred embodiment, the inner diameter of the dispensing syringe of the 3D printer is 290 μm, the printing speed is 1 mm / s-20 mm / s, and the applied pressure of the vacuum pump is 50 psi-100 psi.

[0025] In a preferred embodiment, the concentration of the concentrated sulfuric acid solution is 90%-98%, and the sensor substrate is immersed in the concentrated sulfuric acid solution for 1-10 minutes.

[0026] In a preferred embodiment, the setting temperature of the drying box is 60°C-120°C.

[0027] In a preferred embodiment, rinse with clean water for 20-60 minutes.

[0028] Example 2 On the basis of Example 1, this example proposes a multifunctional flexible pressure sensor having a microstructure 11, which is prepared by the preparation method of the multifunctional flexible pressure sensor having a microstructure 11 as described in Example 1; Figure 2 As shown, it includes a sensor matrix, which is obtained by printing ink through 3D printing technology; the printing ink is formed by adding carbon nanotubes, Mxene to polydimethylsiloxane, and then adding a curing agent and xylene, and stirring; the sensor matrix has a microstructure 11 formed by 3D printing technology, and the surface of the sensor matrix also has a micro-nano structure formed by acidification treatment.

[0029] Specifically, the microstructure 11 is directly obtained by 3D printing technology. After being obtained, the entire sensor substrate is immersed in a concentrated sulfuric acid solution to form a rough surface on its surface. The rough surface is a nanostructure.

[0030] In a preferred embodiment, the thickness of the multifunctional flexible pressure sensor 1 is 1 mm-100 mm. Specifically, the thickness of the multifunctional flexible pressure sensor 1 is the height of the microstructure 11 .

[0031] Specifically, the multifunctional flexible pressure sensor 1 with a microcone structure is applied in human motion health monitoring. The multifunctional flexible pressure sensor 1 with a microstructure 11 can be attached to human joints and skin surfaces to monitor the movement of body parts, such as the bending and stretching of fingers, elbows and knee joints, and the contraction and relaxation of arm and leg muscles.

[0032] Example 3 Based on Example 1, this example proposes a first implementation method of a method for preparing a multifunctional flexible pressure sensor having a microstructure 11: (1) Use 3D design software to design the printed model into a cuboid with a micro-cone structure as the internal printed structure; (2) adding 0.5 g of carbon nanotubes and 1.5 g of Mxene to 8.0 g of polydimethylsiloxane, and stirring magnetically for 1 h at room temperature to obtain a mixed solution; (3) adding the curing agent to the mixed solution at a mass ratio of 1:10 to polydimethylsiloxane, then adding the xylene solution, and stirring for another 10 minutes to prepare a printing ink; (4) The printing ink was transferred into the dispensing syringe of the self-assembled 3D printer. For curing, the temperature platform of the printer was set to 80° C., the printing speed was 4 mm / s, the inner diameter of the printing syringe was 290 μm, and the applied pressure of the vacuum pump was 100 psi, thereby obtaining a sensor substrate with a micro-cone structure of 30 mm×30 mm×5 mm; (5) Soak the sensor substrate in a 92% sulfuric acid solution for 4 minutes for acid treatment; (6) Take out the acid-treated sensor substrate with tweezers, rinse the sensor with running water for 20 minutes to remove the residual sulfuric acid solution in the sensor substrate. After rinsing, place it in a drying oven and set the temperature to 100° C. to obtain a multifunctional flexible pressure sensor 1.

[0033] Example 5 Based on Example 1, this example proposes a second implementation method of a method for preparing a multifunctional flexible pressure sensor with a micro-cone structure: (1) Use 3D design software to design the printed model into a cuboid with a micro-cone structure as the internal printed structure; (2) adding 0.5 g of carbon nanotubes and 1.5 g of Mxene to 8.0 g of polydimethylsiloxane, and stirring magnetically for 1 h at room temperature to obtain a mixed solution; (3) adding the curing agent to the mixed solution at a mass ratio of 1:10 to polydimethylsiloxane, then adding the xylene solution, and stirring for another 10 minutes to prepare a printing ink; (4) The printing ink was transferred into the dispensing syringe of the self-assembled 3D printer. For curing, the temperature platform of the printer was set to 80° C., the printing speed was 4 mm / s, the inner diameter of the printing syringe was 290 μm, and the applied pressure of the vacuum pump was 100 psi, thereby obtaining a sensor substrate with a micro-cone structure of 30 mm×30 mm×2 mm; (5) Soak the sensor substrate in a 92% sulfuric acid solution for 2 minutes for acid treatment; (6) Take out the acid-treated sensor with tweezers, rinse the sensor with running water for 10 minutes to remove the residual sulfuric acid solution in the sensor matrix. After rinsing, place it in a drying oven and set the temperature to 100° C. to obtain a multifunctional flexible pressure sensor 1.

[0034] Example 6 Based on Example 1, this example proposes a third implementation method of a method for preparing a multifunctional flexible pressure sensor with a micro-cone structure: (1) Use 3D design software to design the printed model into a cuboid with a micro-cone structure as the internal printed structure; (2) adding 0.5 g of carbon nanotubes and 1.0 g of Mxene to 8.5 g of polydimethylsiloxane, and stirring magnetically for 1 h at room temperature to obtain a mixed solution; (3) adding the curing agent to the mixed solution at a mass ratio of 1:10 to polydimethylsiloxane, then adding the xylene solution, and stirring for another 10 minutes to prepare a printing ink; (4) The printing ink was transferred into the dispensing syringe of the self-assembled 3D printer. For curing, the temperature platform of the printer was set to 80° C., the printing speed was 4 mm / s, the inner diameter of the printing syringe was 290 μm, and the applied pressure of the vacuum pump was 100 psi, thereby obtaining a sensor substrate with a micro-cone structure of 30 mm×30 mm×5 mm; (5) Soak the sensor substrate in a 92% sulfuric acid solution for 4 minutes for acid treatment; (6) Take out the acid-treated sensor substrate with tweezers, rinse the sensor with running water for 20 minutes to remove the residual sulfuric acid solution in the sensor substrate. After rinsing, place it in a drying oven and set the temperature to 100° C. to obtain a multifunctional flexible pressure sensor 1.

[0035] Example 7 Based on Example 1, this example proposes a fourth implementation method of a method for preparing a multifunctional flexible pressure sensor with a micro-cone structure: (1) Use 3D design software to design the printed model into a cuboid with a micro-cone structure as the internal printed structure; (2) adding 0.5 g of carbon nanotubes and 0.5 g of Mxene to 9.0 g of polydimethylsiloxane, and stirring magnetically for 1 h at room temperature to obtain a mixed solution; (3) adding the curing agent to the mixed solution at a mass ratio of 1:10 to polydimethylsiloxane, then adding the xylene solution, and stirring for another 10 minutes to prepare a printing ink; (4) The printing ink was transferred into the dispensing syringe of the self-assembled 3D printer. For curing, the temperature platform of the printer was set to 80° C., the printing speed was 4 mm / s, the inner diameter of the printing syringe was 290 μm, and the applied pressure of the vacuum pump was 100 psi, thereby obtaining a sensor substrate with a micro-cone structure of 30 mm×30 mm×5 mm; (5) Soak the sensor substrate in a 92% sulfuric acid solution for 4 minutes for acid treatment; (6) Take out the acid-treated sensor substrate with tweezers, rinse the sensor with running water for 20 minutes to remove the residual sulfuric acid solution in the sensor substrate. After rinsing, place it in a drying oven and set the temperature to 100° C. to obtain a multifunctional flexible pressure sensor 1.

[0036] Example 8 On the basis of Example 1, this example proposes a method for setting a printing model and a printing structure, which is used before the method for preparing a multifunctional flexible pressure sensor having a microstructure 11 as proposed in Example 1, and includes the following steps: Determine the target part of the human body where the sensor will be used, retrieve the model mapping table, obtain the target model and target size corresponding to the target part, use the target model as the printing model, and use the target size as the printing size of the printing model; the model mapping table includes multiple human body parts and the target model and target size corresponding to each human body part; Specifically, the target parts include wrists, ankles, knees, soles of feet or backs, etc., and their relevant application requirements and attribute information are collected. This information can be obtained in many ways, such as consulting relevant biomechanical research literature, conducting human anatomy research, or directly performing some simple physical tests on the human body; Acquire application requirements and attribute information of the target part, and select a printing structure and its structural parameters according to the application requirements and the attribute information, wherein the application requirements at least include the sensitivity, pressure range and response characteristics required by the target part, the attribute information includes skin elasticity and shape, and the structural parameters at least include the size of the microstructure 11 and the distance between each two adjacent microstructures 11; The step of selecting and obtaining the printing structure and its structural parameters according to the application requirements and the attribute information specifically includes the following steps: Retrieving and traversing a structure matching table, the structure matching table including a plurality of groups of combinations of the application requirements and the attribute information, and a preferred structure and preferred parameters corresponding to each combination; Using the preferred structure and preferred parameters corresponding to the combination of the application requirements and attribute information corresponding to the target part as the printing structure and its structural parameters; Specifically, the sensitivity is related to the physiological activities or physical phenomena of the target part to be monitored. For example, for monitoring the pulse at the wrist, a higher sensitivity is required, while for monitoring walking pressure at the sole of the foot, a larger pressure range and relatively lower sensitivity are required. The pressure range and response characteristics include the response speed and sensitivity of the pressure; determine the pressure range and response characteristics required for the target part, such as whether a fast response or a slow response is required, whether it is sensitive to static pressure or dynamic pressure, etc.; for attribute information, use a skin elasticity tester to measure the skin elasticity of the target part, and use three-dimensional scanning technology to obtain the shape information of the target part; For example, a structural matching table is given. For parts with high sensitivity and low pressure range requirements, high skin elasticity and complex shapes (such as wrists), a micro-cone structure is preferred, and its structural parameters are: micro-cone height is 100-200μm, micro-cone bottom diameter is 50-100μm, and the distance between adjacent micro-cones is 150-200μm, so as to make full use of the stress concentration effect of the micro-cone and adapt to complex shapes. For parts that require a larger pressure range and have moderate skin elasticity and a relatively flat shape (such as the sole of the foot), a micro-column structure is selected, and the micro-column height can be set to 300-500μm, the micro-column diameter is 200-300μm, and the distance between adjacent micro-columns is 300-400μm to ensure the stability and pressure resistance of the structure. For areas that require moderate sensitivity and pressure range, as well as certain bending requirements (such as the knee), a micro-hemispherical structure can be considered. The micro-hemispherical radius is 150-250μm, and the distance between adjacent micro-hemisphericals is 200-300μm, taking advantage of the flexibility and certain stress concentration capabilities of the micro-hemispherical.

[0037] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A method for preparing a multifunctional flexible pressure sensor with a microstructure, characterized in that: include: Add carbon nanotubes and Mxene into polydimethylsiloxane and stir magnetically to form a mixed solution; Adding a curing agent and xylene into the mixed solution, and stirring to obtain a printing ink; The printing ink is transferred into a dispensing syringe of a 3D printer, and 3D printing is performed according to a set printing model and a printing structure to obtain a sensor substrate corresponding to the printing model, wherein the sensor substrate has a microstructure (11) corresponding to the printing structure, and the microstructure includes at least a microcone structure, a microcolumn structure, and a microhemispherical structure; The sensor substrate is moved to a concentrated sulfuric acid solution for immersion, and an acid treatment is performed so that the surface of the sensor substrate has a micro-nano structure, thereby obtaining a multifunctional flexible pressure sensor (1).

2. The method for preparing a multifunctional flexible pressure sensor with a microstructure according to claim 1, characterized in that: After the sensor substrate is moved to a concentrated sulfuric acid solution for immersion and subjected to acid treatment so that the surface of the sensor substrate has a micro-nano structure, the following steps are also included: The sensor substrate with the micro-nano structure on the surface is taken out from the concentrated sulfuric acid solution, the residual concentrated sulfuric acid on the surface is washed with clean water, and then the sensor substrate is placed in a drying box for drying.

3. The method for preparing a multifunctional flexible pressure sensor with a microstructure according to claim 1, characterized in that: The printing model at least includes a cuboid, a cylinder, a prism and a pyramid.

4. The method for preparing a multifunctional flexible pressure sensor with a microstructure according to claim 1, characterized in that: The mass ratio of carbon nanotubes, Mxene and polydimethylsiloxane in the mixed solution is 4:12:

84.

5. The method for preparing a multifunctional flexible pressure sensor with a microstructure according to claim 1, characterized in that: The inner diameter of the dispensing syringe of the 3D printer is 290 μm, the printing speed is 1 mm / s-20 mm / s, and the applied pressure of the vacuum pump is 50 psi-100 psi.

6. The method for preparing a multifunctional flexible pressure sensor with a microstructure according to claim 1, characterized in that: The concentration of the concentrated sulfuric acid solution is 90%-98%, and the sensor substrate is immersed in the concentrated sulfuric acid solution for 1-10 minutes.

7. The method for preparing a multifunctional flexible pressure sensor with a microstructure according to claim 1, characterized in that: The setting temperature of the drying box is 60℃-120℃.

8. The method for preparing a multifunctional flexible pressure sensor with a microstructure according to claim 2, characterized in that: Rinse with clean water for 20-60 minutes.

9. A multifunctional flexible pressure sensor with a microstructure, prepared by the method for preparing a multifunctional flexible pressure sensor with a microstructure according to any one of claims 1 to 8; characterized in that: The invention comprises a sensor substrate, wherein the sensor substrate is obtained by printing ink through 3D printing technology; the printing ink is formed by adding carbon nanotubes, Mxene to polydimethylsiloxane, and then adding a curing agent and xylene, and stirring; the sensor substrate has a microstructure (11) formed by 3D printing technology, and the surface of the sensor substrate also has a micro-nanostructure formed by acidification treatment.

10. The multifunctional flexible pressure sensor with microstructure according to claim 9, characterized in that: The multifunctional flexible pressure sensor (1) has a thickness of 1 mm to 100 mm.

Images