Flexible sensing film and preparation method thereof

Abstract

The invention provides a flexible sensing film and a preparation method thereof, and relates to the technical field of functional materials.The preparation method of the flexible sensing film comprises the steps that S1, an expanded polytetrafluoroethylene film is polarized so that the surface of the expanded polytetrafluoroethylene film can carry charges, and a polarized expanded polytetrafluoroethylene film is obtained; s2, placing the polarized expanded polytetrafluoroethylene film in liquid silicone rubber, and performing curing treatment to enable the cured silicone rubber to wrap the polarized expanded polytetrafluoroethylene film to form a flexible composite film; s3, preparing a flexible conductive electrode on the upper surface of the flexible composite film to obtain a flexible sensing film; the flexible conductive electrode comprises a silver nanowire. By adopting the method disclosed by the invention, the flexible sensing film with a contact and non-contact dual-mode sensing function can be prepared, and the flexible sensing film has relatively strong capability of resisting the influence of an external environment.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, and more specifically, to a flexible sensing film and its preparation method. Background Technology

[0002] Sensors, as crucial components for acquiring external signals, have significantly improved people's quality of life. The increasing demand for biomimetic and intelligent robots is driving the development of sensors from rigid to flexible. Flexible sensors, due to their flexibility, stretchability, and stability, are attracting growing attention from the scientific and industrial communities. Flexible sensing films are a common type of flexible sensor; however, most existing flexible sensing films can only achieve a single sensing function (such as contact sensing or non-contact sensing), making it difficult to achieve both contact and non-contact dual-modal sensing capabilities. Summary of the Invention The problem solved by this invention is: how to obtain a flexible sensing film that has both contact and non-contact dual-modal sensing functions.

[0003] To address the above problems, this invention provides a method for preparing a flexible sensing film, comprising: Step S1: Polarize the expanded polytetrafluoroethylene film to make its surface carry charge, thus obtaining a polarized expanded polytetrafluoroethylene film. Step S2: Place the polarized expanded polytetrafluoroethylene film in liquid silicone rubber and cure it so that the cured silicone rubber wraps the polarized expanded polytetrafluoroethylene film to form a flexible composite film. Step S3: A flexible conductive electrode is prepared on the upper surface of the flexible composite film to obtain a flexible sensing film; the flexible conductive electrode includes silver nanowires.

[0004] Optionally, in step S1, the polarization treatment includes corona polarization treatment.

[0005] Optionally, the voltage of the corona polarization treatment is 10kV to 15kV, and the time is 5min to 15min.

[0006] Optionally, in step S1, the thickness of the expanded polytetrafluoroethylene film is 10 μm to 100 μm.

[0007] Optionally, in step S2, the thickness of the flexible composite film is 30 μm to 200 μm.

[0008] Optionally, in step S2, the curing temperature is 20°C to 30°C, and the time is 30 min to 60 min.

[0009] Optionally, in step S3, the diameter of the silver nanowire is 50 nm to 100 nm.

[0010] Optionally, in step S3, the preparation of a flexible conductive electrode on the upper surface of the flexible composite film includes: spraying a silver nanowire dispersion onto the upper surface of the flexible composite film to obtain a flexible conductive electrode.

[0011] Optionally, the concentration of the silver nanowire dispersion is from 0.1 mg / mL to 2 mg / mL.

[0012] The present invention also provides a flexible sensing film, which is prepared by the flexible sensing film preparation method described above.

[0013] Compared with related technologies, the flexible sensing film provided by this invention has a high charge density on the surface of the polarized expanded polytetrafluoroethylene (PTFE) film. When a charged target object gradually approaches the flexible sensing film from a distance, the film will strain, causing strain in the flexible conductive electrode (such as silver nanowires). This results in a change in the potential across the electrode, enabling the sensing of non-contact targets. During the contact and separation process between the target object and the film, charge separation occurs on the surface, causing a change in the potential across the electrode, thus enabling the sensing of contact targets. Furthermore, since the polarized PTFE film is completely encapsulated by silicone rubber, it exhibits strong resistance to environmental influences. In summary, the method of this invention can produce a flexible sensing film with both contact and non-contact dual-modal sensing capabilities, and this film also exhibits strong resistance to environmental influences. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the flexible sensing film in an embodiment of the present invention; Figure 2 This is a graph showing the change in potential across the flexible conductive electrode when the distance between the target object and the flexible sensing film in Example 1 changes. Figure 3 This is a diagram showing the change in potential across the flexible conductive electrode during the process of contact and separation between the target object and the flexible sensing film in Example 1.

[0015] Explanation of reference numerals in the attached figures: 1. Polarized expanded polytetrafluoroethylene film; 2. Cured silicone rubber; 3. Flexible conductive electrode. Detailed Implementation

[0016] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0017] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0018] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0019] This invention provides a method for preparing a flexible sensing film, comprising: Step S1: Polarize the expanded polytetrafluoroethylene film to make its surface carry charge, thus obtaining polarized expanded polytetrafluoroethylene film 1. Step S2: Place the polarized expanded polytetrafluoroethylene film 1 in liquid silicone rubber and cure it so that the cured silicone rubber 2 encapsulates the polarized expanded polytetrafluoroethylene film 1 to form a flexible composite film. Step S3: A flexible conductive electrode 3 is fabricated on the upper surface of the flexible composite film to obtain a flexible sensing film, such as... Figure 1 As shown; the flexible conductive electrode 3 comprises silver nanowires.

[0020] The flexible sensing film provided in this invention features a highly charged surface on the polarized expanded polytetrafluoroethylene (PTFE) film. When a charged target object gradually approaches the flexible sensing film from a distance, the film strains, causing strain in the flexible conductive electrode (such as silver nanowires). This strain results in a change in the potential across the electrode, enabling the sensing of non-contact targets. During the contact separation process between the target object and the film, charge separation occurs on the film's surface, causing a change in the potential across the electrode, thus enabling the sensing of contact targets. Furthermore, because the polarized PTFE film is completely encapsulated in silicone rubber, it exhibits strong resistance to environmental influences. In summary, the method described in this invention provides a flexible sensing film with both contact and non-contact dual-modal sensing capabilities, and this film demonstrates strong resistance to environmental influences.

[0021] In some embodiments of the present invention, in step S1, the polarization treatment includes corona polarization treatment; the voltage of the corona polarization treatment is 10kV to 15kV, and the time is 5min to 15min. In this embodiment, by corona polarizing the expanded polytetrafluoroethylene film, a high charge density is formed on its surface.

[0022] In some embodiments of the present invention, in step S1, the thickness of the expanded polytetrafluoroethylene film is 10 μm to 100 μm.

[0023] In some embodiments of the present invention, in step S2, the thickness of the flexible composite film is 30 μm to 200 μm.

[0024] In some embodiments of the present invention, in step S2, the curing temperature is 20°C to 30°C and the time is 30 min to 60 min.

[0025] In some embodiments of the present invention, in step S3, the diameter of the silver nanowire is 50 nm to 100 nm.

[0026] In some embodiments of the present invention, step S3, which involves preparing a flexible conductive electrode 3 on the upper surface of the flexible composite film, includes: spraying a silver nanowire dispersion onto the upper surface of the flexible composite film to obtain the flexible conductive electrode 3; wherein the concentration of the silver nanowire dispersion is from 0.1 mg / mL to 2 mg / mL.

[0027] This invention also provides a flexible sensing film, which is prepared using the flexible sensing film preparation method described above.

[0028] The present invention will be further described below with reference to specific embodiments.

[0029] Example 1 A1. A polarized expanded polytetrafluoroethylene (ePTFE) film is subjected to a corona polarization treatment to make its surface carry a charge, thereby obtaining a polarized ePTFE film; the voltage of the corona polarization treatment is 12.5 kV and the time is 10 min; the thickness of the ePTFE film is 55 μm.

[0030] A2. The polarized expanded polytetrafluoroethylene film is placed in liquid silicone rubber and cured so that the cured silicone rubber encapsulates the polarized expanded polytetrafluoroethylene film to form a flexible composite film; the thickness of the flexible composite film is 120 μm, the curing temperature is 25°C, and the time is 45 min.

[0031] A3. Spray the silver nanowire dispersion onto the upper surface of the flexible composite film to form a flexible conductive electrode on the upper surface of the flexible composite film, thereby obtaining a flexible sensing film; the concentration of the silver nanowire dispersion is 1 mg / mL.

[0032] Example 2 A1. A polarized expanded polytetrafluoroethylene (ePTFE) film is subjected to a polarization treatment to make its surface carry a charge, thereby obtaining a polarized ePTFE film; the voltage of the corona polarization treatment is 15kV and the time is 5min; the thickness of the ePTFE film is 100μm.

[0033] A2. The polarized expanded polytetrafluoroethylene film is placed in liquid silicone rubber and cured so that the cured silicone rubber encapsulates the polarized expanded polytetrafluoroethylene film to form a flexible composite film; the thickness of the flexible composite film is 200 μm, the curing temperature is 25°C, and the time is 45 min.

[0034] A3. Spray the silver nanowire dispersion onto the upper surface of the flexible composite film to form a flexible conductive electrode on the upper surface of the flexible composite film, thereby obtaining a flexible sensing film; the concentration of the silver nanowire dispersion is 1 mg / mL.

[0035] Example 3 A1. A polarized expanded polytetrafluoroethylene (ePTFE) film is subjected to a polarization treatment to make its surface carry a charge, thereby obtaining a polarized ePTFE film; the voltage of the corona polarization treatment is 10 kV and the time is 15 min; the thickness of the ePTFE film is 10 μm.

[0036] A2. The polarized expanded polytetrafluoroethylene film is placed in liquid silicone rubber and cured to allow the cured silicone rubber to encapsulate the polarized expanded polytetrafluoroethylene film, forming a flexible composite film; the thickness of the flexible composite film is 30 μm, and the curing temperature is 25°C for 45 min. A3. Spray the silver nanowire dispersion onto the upper surface of the flexible composite film to form a flexible conductive electrode on the upper surface of the flexible composite film, thereby obtaining a flexible sensing film; the concentration of the silver nanowire dispersion is 1 mg / mL.

[0037] Comparative Example 1 A1. A polarized expanded polytetrafluoroethylene (ePTFE) film is subjected to a corona polarization treatment to make its surface carry a charge, thereby obtaining a polarized ePTFE film; the voltage of the corona polarization treatment is 12.5 kV and the time is 10 min; the thickness of the ePTFE film is 55 μm.

[0038] A3. Spray a silver nanowire dispersion onto the upper surface of a polarized expanded polytetrafluoroethylene film to form a flexible conductive electrode on the upper surface of the expanded polytetrafluoroethylene film, thereby obtaining a flexible sensing film; the concentration of the silver nanowire dispersion is 1 mg / mL.

[0039] Experimental Example A charged target object was gradually brought closer to the flexible sensing film prepared in Example 1 from a distance, and then gradually moved away from the flexible sensing film. The potential change across the flexible conductive electrode was tested during this process. The test results are shown in [Figure 1]. Figure 2 ,from Figure 2 It can be seen that when the distance between the target object and the flexible sensing film changes, the potential across the flexible conductive electrode changes, thereby enabling the sensing of non-contact target objects. Target objects made of aluminum (Al), polyimide (PI), nylon, copper (Cu), skin, acrylic, and paper were repeatedly brought into contact with and separated from the flexible sensing film in Example 1. The change in potential across the flexible conductive electrode during this process was tested, and the test results are shown in [Figure 1]. Figure 3 ,from Figure 3 It can be seen that when the target object contacts and separates from the flexible sensing film, the potential across the flexible conductive electrode changes, thereby enabling the sensing of the contacting target object. It should be noted that... Figure 2 and Figure 3 The units for the vertical axis are all in mV.

[0040] The flexible sensing films prepared in Example 1 and Comparative Example 1 were immersed in water and dried three times, and the changes in their surface potential were measured. The results showed that after immersing in water and drying three times, the surface potential of the flexible sensing film prepared in Example 1 decreased to 80% of the initial potential, and the surface potential of the flexible sensing film prepared in Comparative Example 1 decreased to 10% of the initial potential. The flexible sensing film prepared in Example 1 has a stronger ability to resist the influence of the external environment.

[0041] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for preparing a flexible sensing film, characterized in that, include: Step S1: Polarize the expanded polytetrafluoroethylene film to make its surface carry charge, and obtain polarized expanded polytetrafluoroethylene film (1). Step S2: Place the polarized expanded polytetrafluoroethylene film (1) in liquid silicone rubber and cure it so that the cured silicone rubber (2) wraps the polarized expanded polytetrafluoroethylene film (1) to form a flexible composite film. Step S3: A flexible conductive electrode (3) is prepared on the upper surface of the flexible composite film to obtain a flexible sensing film; the flexible conductive electrode (3) includes silver nanowires.

2. The method for preparing the flexible sensing film according to claim 1, characterized in that, In step S1, the polarization treatment includes corona polarization treatment.

3. The method for preparing the flexible sensing film according to claim 2, characterized in that, The voltage of the corona polarization treatment is 10kV to 15kV, and the time is 5min to 15min.

4. The method for preparing the flexible sensing film according to claim 1, characterized in that, In step S1, the thickness of the expanded polytetrafluoroethylene film is 10 μm to 100 μm.

5. The method for preparing the flexible sensing film according to claim 1, characterized in that, In step S2, the thickness of the flexible composite film is 30 μm to 200 μm.

6. The method for preparing the flexible sensing film according to claim 1, characterized in that, In step S2, the curing temperature is 20°C to 30°C and the time is 30 min to 60 min.

7. The method for preparing the flexible sensing film according to claim 1, characterized in that, In step S3, the diameter of the silver nanowire is 50 nm to 100 nm.

8. The method for preparing the flexible sensing film according to claim 1, characterized in that, In step S3, the preparation of the flexible conductive electrode (3) on the upper surface of the flexible composite film includes: spraying a silver nanowire dispersion onto the upper surface of the flexible composite film to obtain the flexible conductive electrode (3).

9. The method for preparing the flexible sensing film according to claim 8, characterized in that, The concentration of the silver nanowire dispersion is from 0.1 mg / mL to 2 mg / mL.

10. A flexible sensing film, characterized in that, It is prepared using the method for preparing a flexible sensing film as described in any one of claims 1 to 9.

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