Wearable pressure sensor with wide linear detection range and preparation method thereof

Abstract

The invention provides a wearable pressure sensor with a wide linear detection range and a preparation method thereof, and belongs to the technical field of sensing devices. According to the invention, the specially-made strain response film is adhered to the surface of the elastic cylinder, and the normal pressure which is longitudinally applied is converted into the transverse tensile force due to the Poisson effect of the elastic body, so that the strain response film is stretched and deformed. The rigidity mismatching characteristic of the elastic substrate and the rigid conductive layer of the strain response film causes surface cracks to be generated, and high-sensitivity resistance response is generated. The linear detection range of the sensor is 0-4 MPa, the sensitivity reaches up to 380 MPa <-1 >, and meanwhile, the sensor has fast response time and long-time operation stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensor devices, and in particular relates to a wearable pressure sensor with a wide linear detection range and a preparation method thereof. Background Art

[0002] With the popularization and rise of new technologies such as human-computer interaction, health monitoring and virtual reality, flexible wearable electronic devices have achieved great development and progress. Flexible pressure sensors are an important part of the flexible sensing field and are widely used in wearable devices and various fields of flexible electronics. Piezoresistive sensors have low integration, low energy consumption, high sensitivity, and easy signal acquisition. Their principle is based on the pressure-sensitive deformation of the material, which causes changes in its own resistance or electrode interface contact resistance. Sensitivity and linear detection range are important performance indicators of flexible pressure sensors. Existing flexible pressure sensors are mostly suitable for medium and high pressures (~kPa), and flexible pressure sensors with a linear range of MPa have not been widely studied.

[0003] At present, the innovative design of the functional layer microstructure is generally considered to be the most effective means to enhance the performance of flexible sensors, such as interface microstructure, porous structure, multi-level structure, etc. However, the sensitivity of most devices currently decreases rapidly with increasing pressure, and their high sensitivity can only be maintained in a small pressure response range and high pressure range. This sensitivity attenuation phenomenon leads to the problem of a narrow linear detection range, which limits the application of sensors in a wide pressure range. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a wearable pressure sensor with a wide linear detection range and a preparation method thereof. The sensor obtained by the present invention has a wide linear detection range, high sensitivity, fast response time and long-term operation stability.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a wearable pressure sensor with a wide linear detection range, comprising an elastic cylinder and a strain-responsive film;

[0007] The strain responsive film is in a ring shape and adheres to the surface of the cylinder.

[0008] The present invention converts the normal pressure applied longitudinally into a transverse tensile force based on the Poisson effect of the elastic body, causing the strain-responsive film to undergo tensile deformation. The stiffness mismatch between the elastic substrate of the strain-responsive film and the rigid conductive layer causes surface cracks to form, resulting in a highly sensitive resistance response. The highly sensitive resistance response based on cracks can effectively increase the resistance response within a high pressure range, overcome the sensitivity attenuation problem in traditional design methods, and achieve an ultra-wide linear detection range.

[0009] Preferably, the adhesion position of the strain responsive film is the center position of the column height.

[0010] Preferably, the elastic column is made of polydimethylsiloxane or styrene-ethylene-butylene-styrene.

[0011] Preferably, the strain responsive film is prepared by mixing a MXene dispersion and a graphene dispersion, spraying 2 mL on a substrate, and then spin coating a PDMS precursor solution on the sprayed surface of the substrate at a speed of 500 r / min to obtain a strain responsive film after complete curing.

[0012] The strain-responsive film prepared by the present invention is a rigid conductive layer formed by loading MXene and graphene on a PDMS film. When the elastic column is subjected to pressure, the strain-responsive film undergoes tensile deformation. The elastic substrate of the strain-responsive film and the rigid conductive layer have a mismatch in stiffness, which leads to surface cracks and produces a highly sensitive resistance response. The electrical response performance of the strain-responsive film obtained in the present application can be regulated by adjusting the volume ratio of the MXene dispersion to the graphene dispersion, further realizing controllable regulation of the pressure response performance.

[0013] Preferably, the volume ratio of the MXene dispersion to the graphene dispersion is 0-2:1.

[0014] Preferably, the MXene dispersion is a Ti3C2 MXene dispersion.

[0015] Preferably, the concentration of the MXene dispersion is 2 mg / mL.

[0016] Preferably, the concentration of the graphene dispersion is 2 mg / mL.

[0017] Preferably, the weight ratio of PDMS monomer to curing agent in the PDMS precursor solution is 10:1.

[0018] Preferably, the spin coating speed is 500 r / min.

[0019] Preferably, the curing temperature is 80° C. and the curing time is 60 min.

[0020] Preferably, the strain responsive film is further connected to an external lead.

[0021] In a second aspect, the present invention provides a method for preparing the wearable pressure sensor, comprising the following steps:

[0022] 1) preparing a casting template by 3D printing, and then pouring the precursor solution into the 3D printed template to obtain an elastic column after curing and demoulding;

[0023] 2) Cut the strain-responsive film into a rectangle and then adhere it to the outside of the elastic cylinder in a ring shape.

[0024] Contains at least the following beneficial technical effects:

[0025] The present invention adheres a specially made strain-responsive film to the surface of an elastic cylinder. Due to the Poisson effect of the elastic body, the normal pressure applied longitudinally is converted into a transverse tensile force, causing the strain-responsive film to undergo tensile deformation. The stiffness mismatch between the elastic substrate of the strain-responsive film and the rigid conductive layer causes surface cracks to form, resulting in a highly sensitive resistance response. The linear detection range of the sensor obtained by the present invention is 0-4MPa, and the sensitivity is as high as 380MPa. -1 , while having fast response time and long-term operating stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Diagram of the pressure sensor structure and response mechanism.

[0027] Figure 2 Response performance diagram of different pressure sensors.

[0028] Figure 3 This is the ultra-wide linear detection range and sensitivity detection diagram of the pressure sensor.

[0029] Figure 4 Detection diagram of the fast response time and recovery time of the pressure sensor.

[0030] Figure 5 Figure 2 shows the stable response of the pressure sensor after 10,000 cycles of repeated compression. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0032] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0033] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the main idea or essential features of the present invention. Therefore, from all points of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0034] In addition, it should be understood that although this specification is described according to the implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. These other implementation modes are also covered within the protection scope of the present invention.

[0035] It should also be understood that the specific embodiments described above are only used to explain the present invention, and the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the protection scope of the present invention / invention.

[0036] Example 1

[0037] This embodiment provides a wearable pressure sensor with a wide linear detection range, and the preparation method is as follows:

[0038] 1) Preparation of elastic cylinder: A casting template with a height of 10 mm and a diameter of 10 mm was prepared by 3D printing, PDMS monomer and curing agent were mixed in a weight ratio of 10:1, degassed, poured into the 3D printed template, placed in an oven at 80°C for curing for 60 min, and the elastomer was obtained after demolding.

[0039] 2) Preparation of strain-responsive film: Spray 2 mL of 2 mg / mL graphene dispersion onto a polytetrafluoroethylene substrate, then spin-coat the PDMS precursor solution (monomer to curing agent in a weight ratio of 10:1) on the sprayed surface of the substrate at a speed of 500 r / min, and then place in an 80°C oven for curing for 60 min. After complete curing, cut into 3 mm wide rectangular films.

[0040] 3) The strain-responsive film is adhered to the outside of the height center of the PDMS elastomer using a silicone adhesive, and an external lead (silver-plated fiber wire) is connected to obtain a pressure sensor.

[0041] Example 2

[0042] This embodiment provides a wearable pressure sensor with a wide linear detection range. The preparation method is the same as that of Example 1. The only difference is that the strain-responsive thin film Ti3C2 MXene dispersion and the graphene dispersion are mixed in a volume ratio of 0.5:1.

[0043] Example 3

[0044] This embodiment provides a wearable pressure sensor with a wide linear detection range. The preparation method is the same as that of Example 1. The only difference is that the strain-responsive thin film Ti3C2 MXene dispersion and the graphene dispersion are mixed in a volume ratio of 1:1.

[0045] Example 4

[0046] This embodiment provides a wearable pressure sensor with a wide linear detection range. The preparation method is the same as that of Example 1. The only difference is that the strain-responsive thin film Ti3C2 MXene dispersion and the graphene dispersion are mixed in a volume ratio of 1.5:1.

[0047] Example 5

[0048] This embodiment provides a wearable pressure sensor with a wide linear detection range. The preparation method is the same as that of Example 1. The only difference is that the strain-responsive thin film Ti3C2 MXene dispersion and the graphene dispersion are mixed in a volume ratio of 2:1.

[0049] Example 6

[0050] This embodiment provides a wearable pressure sensor with a wide linear detection range, and the preparation method is as follows:

[0051] 1) Preparation of elastic cylinder: A casting template with a height of 10 mm and a diameter of 10 mm was prepared by 3D printing, PDMS monomer and curing agent were mixed in a weight ratio of 10:1, degassed, poured into the 3D printed template, placed in an oven at 80°C for curing for 60 min, and the elastomer was obtained after demolding.

[0052] 2) Preparation of strain-responsive film: 2 mg / mL of Ti3C2 MXene dispersion and 2 mg / mL of graphene dispersion were mixed in a volume ratio of 0.5:1, 2 mL was sprayed on a polytetrafluoroethylene substrate, and then PDMS precursor solution (monomer to curing agent in a weight ratio of 10:1) was spin-coated on the sprayed surface of the substrate at a speed of 500 r / min, and then placed in an 80°C oven for curing for 60 min. After complete curing, it was cut into a rectangular film with a width of 3 mm.

[0053] 3) The strain-responsive film is adhered to the outside of the height center of the PDMS elastomer using a silicone adhesive, and an external lead (silver-plated fiber wire) is connected to obtain a pressure sensor.

[0054] Example 7

[0055] The preparation method of this embodiment is the same as that of embodiment 5, except that the size of the elastomer is 8 mm in height and 14 mm in diameter.

[0056] Example 8

[0057] The preparation method of this embodiment is the same as that of embodiment 5, except that the size of the elastomer is 14 mm in height and 10 mm in diameter.

[0058] Experimental Example 1

[0059] A small stepper motor is used to apply pressure to the sensor. The pressure signal generated is measured by a commercial weighing sensor, and the resistance signal is measured by an LCR meter (TH2840A). The test results are as follows: Figure 2-5 As shown; the linear detection range of the sensor obtained by the present invention is 0-4MPa, and the sensitivity is as high as 380MPa -1 , and at the same time has fast response time and long-term operation stability; and after testing, the present invention can be used for various types of elastomers and has a wide range of applications.

[0060] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A wearable pressure sensor with a wide linear detection range, characterized in that: including an elastic cylinder and a strain-responsive film; The strain responsive film is in a ring shape and adheres to the surface of the cylinder.

2. The wearable pressure sensor according to claim 1, characterized in that The elastic column is made of polydimethylsiloxane or styrene-ethylene-butylene-styrene.

3. The wearable pressure sensor according to claim 1, characterized in that The preparation method of the strain responsive film is as follows: a MXene dispersion and a graphene dispersion are mixed and evenly mixed, and then 2 mL is sprayed on a substrate, and then a PDMS precursor solution is spin-coated on the sprayed surface of the substrate at a speed of 500 r / min, and the strain responsive film is obtained after the solution is completely cured.

4. The wearable pressure sensor according to claim 3, characterized in that: The volume ratio of the MXene dispersion to the graphene dispersion is 0-2:1; and the MXene dispersion is a Ti3C2 MXene dispersion.

5. The wearable pressure sensor according to claim 4, characterized in that: The concentration of the MXene dispersion is 2 mg / mL.

6. The wearable pressure sensor according to claim 4, characterized in that: The concentration of the graphene dispersion is 2 mg / mL.

7. The wearable pressure sensor according to claim 3, characterized in that: The weight ratio of PDMS monomer to curing agent in the PDMS precursor solution is 10:

1.

8. The wearable pressure sensor according to claim 3, characterized in that: The curing temperature is 80° C. and the curing time is 60 min.

9. The wearable pressure sensor according to claim 1, characterized in that: The strain responsive film is also connected to an external lead.

10. The method for preparing a wearable pressure sensor according to any one of claims 1 to 9, characterized in that: The following steps are involved: 1) preparing a casting template by 3D printing, and then pouring an elastic precursor solution into the 3D printed template to obtain an elastic column after curing and demoulding; 2) Cut the strain-responsive film into a rectangle and then adhere it to the outside of the elastic cylinder in a ring shape.

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