A TPU-based flexible electronic skin and its preparation method

Abstract

The present invention relates to a TPU flexible electronic skin and a method for preparing the same. The flexible electronic skin comprises: a first conductive TPU film, a second conductive TPU film, and an insulating TPU film; the lower surface of the first conductive TPU film is connected to the upper surface of the insulating TPU film; the lower surface of the insulating TPU film is connected to the upper surface of the second conductive TPU film; and electrodes and circuits are engraved on the first conductive TPU film and / or the second conductive TPU film. Because TPU films are flexible, stretchable, come in a variety of thicknesses, and have a stable relative dielectric constant, the resulting flexible electronic skin is stretchable, flexible, and resistant to breakage.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible electronic skin, and in particular to a TPU-based flexible electronic skin and a preparation method thereof. Background Art

[0002] At present, flexible electronic skin is widely used in carriers such as robots, medical equipment, human prostheses, wearable devices, etc., and has positive significance for many fields such as production and life, rehabilitation medicine, etc.

[0003] In the existing technology, the preparation of flexible electronic skin is as follows: 1) Flexible electronic skin uses PI as a dielectric and Cu as an electrode, which is a typical FPC production process. However, the thickness of PI in this method is relatively thin, generally 30 to 150um, making it difficult to adjust the electrical properties of the sensor in the thickness direction. If the PI thickness is forcibly increased, the flexibility of the electronic skin will be greatly reduced, and the electronic skin produced by this process is not stretchable. 2) Flexible electronic skin uses PDMS as a dielectric and PDMS doped with conductive materials as electrodes. This method has high requirements for the design of the mold for curing PDMS. When electronic skin is often made in a large area and requires to be thin, and the electrode pattern is complex, PDMS is easily damaged during the production process. 3) Flexible electronic skin uses PDMS as a dielectric and silver nanowires or graphite as electrodes. This electrode material can cope with complex electrode patterns, but they have poor bonding with PDMS, and the electrodes made are prone to breakage. Summary of the Invention

[0004] The purpose of the present invention is to provide a stretchable and flexible TPU-based flexible electronic skin and a preparation method thereof.

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

[0006] A TPU-based flexible electronic skin, comprising: a first conductive TPU film, a second conductive TPU film, and an insulating TPU film;

[0007] The lower surface of the first conductive TPU film is connected to the upper surface of the insulating TPU film; the lower surface of the insulating TPU film is connected to the upper surface of the second conductive TPU film; the first conductive TPU film and / or the second conductive TPU film are engraved with electrodes and circuits.

[0008] Optionally, the first conductive TPU film and the second conductive TPU film are made of opaque materials, and the insulating TPU film is made of transparent material.

[0009] Optionally, the first conductive TPU film, the second conductive TPU film and the insulating TPU film are connected by gluing.

[0010] Optionally, the TPU in the first conductive TPU film and the second conductive TPU film contains carbon black.

[0011] Optionally, the electrode includes a square electrode structure and / or a circular electrode structure, the square electrode structure includes a square transmitting electrode and a linear receiving electrode structure around the square transmitting electrode, and the circular electrode structure includes a circular transmitting electrode and a ring-shaped receiving electrode structure around the circular transmitting electrode.

[0012] Optionally, the dielectric constant of the insulating TPU film ranges from 4 to 8.

[0013] Optionally, the size of the insulating TPU film ranges from 30 mm×30 mm to 300 mm×300 mm, and the thickness ranges from 50 to 2000 um.

[0014] Optionally, the first conductive TPU film and the second conductive TPU film have a square resistance of less than 60Ωm and a thickness of less than 100um.

[0015] The present invention also provides a method for preparing flexible electronic skin based on TPU, comprising the following steps:

[0016] Obtain a first conductive TPU film, a second conductive TPU film, and an insulating TPU film;

[0017] Using the insulating TPU film as a substrate, connecting the lower surface of the first conductive TPU film to the upper surface of the insulating TPU film;

[0018] connecting the upper surface of the second conductive TPU film to the lower surface of the insulating TPU film;

[0019] Electrodes and circuit patterns are engraved on the first conductive TPU film and / or the second conductive TPU film to obtain a flexible electronic skin.

[0020] Optionally, the engraving method of the electrode and circuit pattern is laser engraving.

[0021] According to the specific embodiments provided by the present invention, the following technical effects are disclosed: The present invention provides a TPU-based flexible electronic skin and a preparation method thereof, wherein the flexible electronic skin comprises: a first conductive TPU film, a second conductive TPU film, and an insulating TPU film. The lower surface of the first conductive TPU film is connected to the upper surface of the insulating TPU film, and the lower surface of the insulating TPU film is connected to the upper surface of the second conductive TPU film. Electrodes and circuits are engraved on the first conductive TPU film and / or the second conductive TPU film. Since the present invention uses TPU film to prepare the flexible electronic skin, and since the TPU film has the characteristics of good flexibility, stretchability, a variety of thickness types, and a stable relative dielectric constant, the prepared flexible electronic skin is stretchable, flexible, and not easy to break. 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. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a structural diagram of the flexible electronic skin provided by the present invention;

[0024] Figure 2 A schematic diagram of the process for preparing the flexible electronic skin provided by the present invention;

[0025] Figure 3 This is a schematic diagram of the process of laser engraving of the flexible electronic skin provided by the present invention;

[0026] Figure 4 This is a structural diagram of the receiving electrode and transmitting electrode of the flexible electronic skin provided by the present invention.

[0027] Explanation of symbols: 1-first conductive TPU film, 2-second conductive TPU film, 3-insulating TPU film. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] The purpose of the present invention is to provide a flexible electronic skin based on TPU and a preparation method thereof.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] The present invention provides a flexible electronic skin based on TPU, such as Figure 1 As shown, it includes: a first conductive TPU film 1, a second conductive TPU film 2 and an insulating TPU film 3; the lower surface of the first conductive TPU film 1 is connected to the upper surface of the insulating TPU film 3; the lower surface of the insulating TPU film 3 is connected to the upper surface of the second conductive TPU film 2; the first conductive TPU film 1 and / or the second conductive TPU film 2 are engraved with electrodes and circuits.

[0032] In this embodiment, the flexible electronic skin uses TPU material as the basic material of the electronic skin. TPU is a thermoplastic elastomer (thermoplastic polyurethane elastomer, also known as thermoplastic polyurethane rubber), which is considered to be a low-cost green and environmentally friendly material.

[0033] Among them, the film composed of TPU has a variety of thickness types to choose from, and the relative dielectric constant of the TPU film is close to FR4.

[0034] Specifically, the first and second conductive TPU films 1 and 2 serve as the electrode layers of the flexible electronic skin. The TPU is doped with varying amounts of carbon black based on the required sheet resistance (sheet resistance refers to the resistance between the edges of a square of thin-film conductive material). Because the electrode layers of the flexible electronic skin require the inscription of electrodes and circuits, the first and second conductive TPU films 1 and 2 are made of opaque materials.

[0035] Specifically, the insulating TPU film 3 is used as the electrolyte layer of the flexible electronic skin, and the material used is a transparent material.

[0036] In some embodiments, the parameters of the first conductive TPU film 1 and the second conductive TPU film 2 may be as follows:

[0037] The first conductive TPU film 2 and the second conductive TPU film 2 should have a square resistance of less than 60Ωm, a thickness of less than 100um, and be adhesive-coated on one side.

[0038] In some embodiments, the parameters of the insulating TPU film 3 may be as follows:

[0039] The dielectric constant of the transparent insulating TPU film 3 is in the range of 4 to 8, the thickness is between 50 and 2000 μm, and the square size is between 30 mm×30 mm and 300 mm×300 mm.

[0040] In practical applications, since the Young's modulus of TPU is very small, and the Young's modulus of C-doped TPU and TPU is very similar, the multi-layer TPU sensor will not fail due to bending. Therefore, the connection between the first conductive TPU film 1 and the second conductive TPU film 2 and the insulating TPU film 3 can be firmly bonded together only by gluing.

[0041] Specifically, such as Figure 3 As shown, the lower surface of the first conductive TPU film 1 is adhered to the upper surface of the insulating TPU film 3 , and the lower surface of the insulating TPU film 3 is adhered to the upper surface of the second conductive TPU film 2 .

[0042] In some embodiments, as Figure 4 As shown, electrodes and circuits are engraved on the first conductive TPU film 1 and the second conductive TPU film 2. The specific engraved electrode structure can be as follows:

[0043] The electrodes include a square electrode structure and / or a circular electrode structure, wherein the square electrode structure includes a square transmitting electrode and a linear receiving electrode structure around the square transmitting electrode, and the circular electrode structure includes a circular transmitting electrode and a ring-shaped receiving electrode structure around the circular transmitting electrode.

[0044] The present invention also provides a method for preparing flexible electronic skin based on TPU, comprising the following steps:

[0045] Obtain a first conductive TPU film 1, a second conductive TPU film 2 and an insulating TPU film 3; using the insulating TPU 3 film as a substrate, connect the lower surface of the first conductive TPU film 1 to the upper surface of the insulating TPU film 3; connect the upper surface of the second conductive TPU film 2 to the lower surface of the insulating TPU film 3; and perform engraving of electrodes and circuit patterns on the first conductive TPU film 1 and / or the second conductive TPU film 2 to obtain a flexible electronic skin.

[0046] In some embodiments, the first conductive TPU film 1 , the second conductive TPU film 2 and the insulating TPU film 3 can be connected by rolling, so that the first conductive TPU film 1 and the second conductive TPU film 2 are respectively bonded to the upper surface and the lower surface of the insulating TPU 3 .

[0047] In some embodiments, the electrode and circuit pattern engraving process is laser engraving. Because an overly strong light source can cause the TPU edge to burn or even penetrate the transparent insulating TPU film 3, the engraving laser should select an appropriate light source, pulse frequency, and pulse width. The present invention uses the laser processing PWM frequency set to 5kHz, the PWM pulse width to 100us, and the engraving speed to 200bit / ms as an example to engrave the first conductive TPU film 1 and / or the second conductive TPU film 2. The specific engraving method can be as follows:

[0048] When the electrodes of the flexible electrode skin are engraved only on the first conductive TPU film 1 or only on the second conductive TPU film 2, the electrode engraving structure type can be selected as a square electrode structure or a circular electrode structure, and then the PWM frequency of the laser processing is set to 5kHz, the PWM pulse width is 100us, and the engraving speed is 200Bit / ms, and the first conductive TPU film 1 or the second conductive TPU film 2 is engraved to realize the production of a single-layer circuit.

[0049] When the electrodes of the flexible electrode skin are engraved on the first conductive TPU film 1 and the second conductive TPU film 2, the electrode engraving structure type can be selected from a square electrode structure or a circular electrode structure. For example, the first conductive TPU film 1 is engraved with a square electrode structure, and the second conductive TPU film 2 is engraved with a circular electrode structure, or both the first conductive TPU film 1 and the second conductive TPU film 2 are engraved with a square electrode structure. Since one engraving machine is used to engrave the two TPU films, after the first conductive TPU film 1 is engraved, when the second conductive TPU film 2 is engraved, the device needs to be repositioned on the workbench, and the device is marked with a laser to ensure positioning accuracy. After the conductive TPU circuits of the first conductive TPU film 1 and the second conductive TPU film 2 are engraved, it is necessary to connect the two layers of the conductive TPU circuits, that is, use a strong laser light source to penetrate through the through hole to achieve the production of a double-layer circuit.

[0050] In summary, the present invention has the following advantages: 1) The flexible electronic skin provided by the present invention includes: a first conductive TPU film, a second conductive TPU film and an insulating TPU film; the lower surface of the first conductive TPU film is connected to the upper surface of the insulating TPU film; the lower surface of the insulating TPU film is connected to the upper surface of the second conductive TPU film; the first conductive TPU film and / or the second conductive TPU film are engraved with electrodes and circuits. 2) Since the present invention uses TPU film to prepare flexible electronic skin, and since TPU film has the characteristics of good flexibility, stretchability, multiple thickness types and stable relative dielectric constant, the prepared flexible electronic skin is stretchable, flexible and not easy to break. 3) The present invention selects a combination of transparent materials and opaque materials, so that the laser processing parameters have a relatively loose selection space. 4) The thickness of the flexible electronic skin in the present invention has a lot of room for expansion, and complex patterns can be engraved on the electrodes to enable the flexible electronic skin to achieve the function of proximity perception.

[0051] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0052] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A flexible electronic skin based on TPU, characterized in that: include: A first conductive TPU film, a second conductive TPU film, and an insulating TPU film; the lower surface of the first conductive TPU film is connected to the upper surface of the insulating TPU film; the lower surface of the insulating TPU film is connected to the upper surface of the second conductive TPU film; the first conductive TPU film and / or the second conductive TPU film are engraved with electrodes and circuits; The first conductive TPU film and the second conductive TPU film are made of opaque materials, and the insulating TPU film is made of transparent material.

2. The TPU-based flexible electronic skin according to claim 1, characterized in that: The first conductive TPU film, the second conductive TPU film and the insulating TPU film are connected by gluing.

3. The TPU-based flexible electronic skin according to claim 1, characterized in that: The TPU in the first conductive TPU film and the second conductive TPU film contains carbon black.

4. The TPU-based flexible electronic skin according to claim 1, characterized in that: The electrode includes a square electrode structure or a circular electrode structure. The square electrode structure includes a square transmitting electrode and a linear receiving electrode structure around the square transmitting electrode. The circular electrode structure includes a circular transmitting electrode and a ring-shaped receiving electrode structure around the circular transmitting electrode.

5. The TPU-based flexible electronic skin according to claim 1, characterized in that: The dielectric constant of the insulating TPU film ranges from 4 to 8.

6. The TPU-based flexible electronic skin according to claim 1, characterized in that: The size of the insulating TPU film ranges from 30 mm×30 mm to 300 mm×300 mm, and the thickness ranges from 50 to 2000 μm.

7. The TPU-based flexible electronic skin according to claim 1, characterized in that: The first conductive TPU film and the second conductive TPU film have a square resistance of less than 60Ωm and a thickness of less than 100um.

8. A method for preparing a TPU-based flexible electronic skin, applied to the TPU-based flexible electronic skin according to any one of claims 1 to 7, characterized in that: The following steps are involved: Obtain a first conductive TPU film, a second conductive TPU film, and an insulating TPU film; using the insulating TPU film as a substrate, connect the lower surface of the first conductive TPU film to the upper surface of the insulating TPU film; connect the upper surface of the second conductive TPU film to the lower surface of the insulating TPU film; and perform engraving of electrodes and circuit patterns on the first conductive TPU film and / or the second conductive TPU film to obtain a flexible electronic skin.

9. The method for preparing TPU-based flexible electronic skin according to claim 8, characterized in that: The electrode and circuit pattern are engraved by laser engraving.

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