Flexible and ultrathin non-contact screen sensor and preparation method thereof

Abstract

The invention belongs to the technical field of sensing, and relates to a flexible and ultrathin non-contact screen sensor and a preparation method thereof. A three-layer structural design is adopted, the electret polymer film is taken as a core material, the characteristics of lightness, thinness, flexibility and full transparency of the electret polymer film are fully utilized, and the electrostatic induction effect of the electret is combined, so that the screen sensor integrating high flexibility, ultra-lightness, full transparency and non-contact sensing characteristics is realized; meanwhile, the array arrangement of the screen sensor can be flexibly designed to realize non-contact contour recognition and sensing, and various application requirements are met. Compared with the prior art, the invention has the advantages of controllable thickness, large-area film formation, low cost, simple structure, simple preparation flow and processing technology and the like.

Description

Technical Field

[0001] The invention belongs to the field of sensor technology and relates to a flexible, ultra-light and thin non-contact screen sensor and a preparation method thereof. Background Art

[0002] In today's society, screen sensors have become a widely used technology in electronic devices, such as smart phones, tablet computers, interactive whiteboards, etc. Screen sensors enable devices to make corresponding instructions to the system by detecting the user's direct operation actions. However, the screen sensors widely used at present are touch screen sensors. Users must touch the screen for the sensor to receive corresponding instructions, which also limits the recognition and sensing of other user actions besides touch.

[0003] In view of the above limitations of touch screen sensors, non-contact screen sensors have gradually attracted people's attention and research because they can be operated without direct contact with the screen. This type of sensor can accurately detect user gestures and movements without touching the screen. In practical applications, it can effectively reduce the risk of infectious disease transmission, especially in public places such as hospitals, transportation hubs and commercial places, where users can operate electronic devices without direct contact with the screen. At the same time, non-contact technology can enhance the user experience and can flexibly manipulate the target device through other body movements. In addition, in some highly polluted or special operating environments, non-contact technology can more effectively keep the screen clean and the operation accurate, extend the service life of the screen, and can adapt well to specific environmental requirements.

[0004] However, current non-contact screen sensors are mainly realized by using special optical panels, organic photodetector arrays or near-infrared cameras (vision, radio frequency) and other technologies. The materials that make up transparent non-contact screen sensors are rigid or brittle and non-stretchable, which makes it difficult to meet the development needs of wearable electronic products. In addition, existing non-contact screen sensors are also limited by insufficient transparency and limited gesture recognition types.

[0005] Patent CN111950529A provides an optical fingerprint sensor with non-contact imaging capability. Based on the optical sensor array, optical fingerprint sensing can be performed to perform user authentication when accessing the device when the user's finger is near the device but not touching the device, and when the user's finger is in contact with the device. However, the sensor has poor transparency and an external power supply module is required, which will cause additional energy consumption. At the same time, the fingerprint anti-spoofing feature of the sensor needs to be combined with the fingerprint image of the contact finger to be realized, and the device flexibility is not high. Patent application CN116753993A discloses a non-contact capacitive sensor, including a shell body on the surface, a connecting plate arranged in the inner cavity of the shell body, and a mounting plate arranged on one side of the connecting plate. The non-contact capacitive sensor forms parasitic capacitances between the byte slice and the surface of the shell body and between the noise reduction terminal line and the shell body. After the finger generates the newly added electrostatic capacitance, the detected signal is sent to the circuit main board to achieve rapid detection without touch pressing. The sensor has a large detection area and a low error probability. However, in addition to being non-transparent and requiring an external power supply module, an electroplating process is also required when preparing the shell body, which results in a high degree of pollution. At the same time, the device has high mechanical strength and cannot be used in application scenarios of flexible electronics such as wearables.

[0006] Patent application CN117024662A discloses a stretchable, wearable, transparent, non-contact screen sensor and its preparation method. The screen sensor has the characteristics of self-power supply and can use the charge naturally carried by the human hand to identify various types of gestures. However, the sensor has the disadvantages of complex preparation process and poor lightness and thinness. Patent application CN113220153A discloses a non-contact flexible transparent sensor and its preparation method. The sensor is composed of an insulating support layer at the bottom and a conductive sensing layer deposited on the surface of the insulating support layer. The contact surface between the insulating support layer and the conductive sensing layer is a composite rough surface, which can improve the signal strength of the sensor and the amplitude of the output signal; the sensor detects the redistribution of charge on the surface of the sensing layer caused by hand movement, realizes gesture-based non-contact sensing and control, and has higher sensitivity. However, the Young's modulus of the sensing layer material of the sensor is large, and it has the disadvantages of poor lightness and low flexibility, and the preparation process is complicated. Summary of the invention

[0007] The purpose of the present invention is to provide a flexible, ultra-thin, non-contact screen sensor and its preparation method in order to overcome the defects of the above-mentioned prior art. The screen sensor has a simple structure and is easy to manufacture. While achieving flexibility, lightness, and full transparency, it can also realize distance sensing of external objects, three-dimensional contour recognition, and non-contact human-computer interaction.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] The present invention provides a flexible, ultra-light and thin non-contact screen sensor. The sensor has a three-layer structure, including: a surface polarization layer, a conductive sensing layer and a bottom adhesion layer. The surface polarization layer is distributed with charges. The conductive sensing layer is arranged between the surface polarization layer and the bottom adhesion layer, and leads out a wire to connect an external load circuit to generate a corresponding induced current in the external load circuit. The conductive sensing layer is adhered to one side of the bottom adhesion layer, and a target device is adhered to the other side. The surface polarization layer, the conductive sensing layer and the bottom adhesion layer of the sensor are all made of transparent materials.

[0010] Furthermore, the thickness of the surface polarization layer is 0.001-1 mm, the thickness of the conductive induction layer is 0.1-1 μm, and the thickness of the bottom adhesion layer is 0.01-0.1 mm.

[0011] Furthermore, the surface polarization layer is made of a transparent electret film material, which is any one of a transparent polylactic acid film layer, a transparent polypropylene film layer, a transparent fluorinated ethylene propylene copolymer film layer or other transparent electret film layers.

[0012] Furthermore, the transparent electret film material is obtained by doping polar particles (such as silicon dioxide, polytetrafluoroethylene) into a transparent base material (such as polydimethylsiloxane, platinum silicone Ecoflex).

[0013] Furthermore, the conductive sensing layer is made of a transparent conductive material, which is any one of a transparent conductive metal electrode layer, a transparent conductive hydrogel electrode layer or a transparent conductive oxide electrode layer.

[0014] Furthermore, the transparent conductive metal electrode layer is a silver nanowire layer; the transparent conductive hydrogel electrode layer is a polyacrylamide hybrid hydrogel layer; and the transparent conductive oxide electrode layer is an indium tin oxide layer.

[0015] Furthermore, the bottom surface adhesion layer is any one of a transparent organic coating, a transparent inorganic coating, and a transparent polymer coating.

[0016] Furthermore, the transparent polymer coating is a transparent PET tape or a transparent VHB tape.

[0017] The present invention also provides a method for preparing any of the above-mentioned flexible, ultra-thin non-contact screen sensors, comprising the following steps:

[0018] S1, disposing a transparent conductive material on one side of the transparent electret film material to form a conductive sensing layer;

[0019] S2, performing polarization treatment on the side of the transparent electret film material where the conductive sensing layer is not provided, to obtain a surface polarization layer with distributed charges;

[0020] S3, adhering the bottom adhesive layer to one side of the conductive sensing layer in step S2, to obtain a transparent non-contact screen sensor having a three-layer structure of surface polarization layer / conductive sensing layer / bottom adhesive layer.

[0021] Furthermore, the conductive induction layer described in step S1 is to arrange the transparent conductive material on one side of the transparent electret film material by thermal evaporation coating, magnetron sputtering or coating; the polarization treatment described in step S2 is to use corona polarization, thermal polarization, ion implantation or electron beam implantation to make the transparent electret film material have charges distributed to form a surface polarization layer, and the conductive induction layer generates induced charges accordingly.

[0022] When an object approaches the screen sensor, the electrostatic induction effect will change the induced charge in the conductive sensing layer of the screen sensor, and then a corresponding induced current will be generated in the external load circuit. By measuring the output voltage across the external load, the position or shape of the external object can be determined.

[0023] Furthermore, the screen sensors obtained in step S3 are combined into a cross-shaped array or other shaped arrays as required to prepare a flexible, ultra-thin array-type non-contact screen sensor.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The present invention solves the defects of existing non-contact screen sensors, such as poor lightness and thinness and insufficient overall flexibility. Relying on the excellent characteristics of lightness, thinness, flexibility and full transparency of electret polymer film materials, combined with the electrostatic induction effect, the present invention innovatively designs a three-layer non-contact screen sensor. This design not only gives the sensor the characteristics of high flexibility, ultra-thinness and full transparency, but also simplifies the preparation process, making it possible to flexibly design the sensor array to adapt to a variety of application scenarios and achieve accurate non-contact contour recognition and sensing.

[0026] (2) The non-contact screen sensor of the present invention uses an electret film, which is a dielectric material that can store space charge and / or dipole charge for a long time and can generate a stable electrostatic field. Based on the sensitivity of the electret material to changes in charge distribution or electric field strength, the sensor of the present invention can be used to detect the approach and movement of external objects. The approach of an object will cause changes in the electric field around the electret material, thereby changing the charge distribution, thereby realizing the sensing of the distance of the object, the recognition of the three-dimensional contour, and non-contact human-computer interaction. Especially in highly polluted or special operating environments, the sensor of the present invention can significantly improve the cleanliness of the screen and the accuracy of operation, extend the service life, and meet the application requirements of specific environments.

[0027] (3) The non-contact screen sensor of the present invention has high flexibility in design, controllable thickness, easy large-area film formation, simple device structure and processing technology, low preparation cost, and has important application value in the field of flexible and ultra-thin non-contact screen sensors. In addition, the sensor of the present invention shows great potential in a variety of application scenarios such as smart phones, computer screens, security inspection equipment, automotive systems, and smart home products, providing strong support for achieving efficient and convenient non-contact human-computer interaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the screen sensor structure of the device of the present invention;

[0029] Figure 2 This is a schematic diagram of a non-contact sensor device array prepared based on a three-layer structure screen sensor of the present invention.

[0030] Description of the markings in the figure:

[0031] 1-transparent surface polarization layer, 2-transparent conductive sensing layer, 3-transparent bottom adhesion layer, 4-resistor, 5-screen sensor of three-layer structure. DETAILED DESCRIPTION

[0032] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0033] The present invention provides a flexible, ultra-thin non-contact screen sensor, which has a three-layer structure, including: a surface polarization layer, a conductive sensing layer and a bottom adhesion layer, wherein the surface polarization layer is distributed with electric charges, the conductive sensing layer is arranged between the surface polarization layer and the bottom adhesion layer, and leads out a wire to connect an external load circuit, generating a corresponding induced current in the external load circuit, the conductive sensing layer is adhered to one side of the bottom adhesion layer, and the target device is adhered to the other side; the surface polarization layer, the conductive sensing layer and the bottom adhesion layer of the sensor are all made of transparent materials. The thickness of the surface polarization layer is 0.001-1mm, the thickness of the conductive sensing layer is 0.1-1μm, and the thickness of the bottom adhesion layer is 0.01-0.1mm.

[0034] In some specific embodiments, the surface polarization layer is made of a transparent electret film material, which is any one of a transparent polylactic acid film layer, a transparent polypropylene film layer, a transparent fluorinated ethylene propylene copolymer film layer or other transparent electret film layers.

[0035] In some specific embodiments, the transparent electret film material is obtained by doping polar particles (such as silicon dioxide, polytetrafluoroethylene) into a transparent base material (such as polydimethylsiloxane, platinum silicone Ecoflex).

[0036] In some specific embodiments, the conductive sensing layer is made of a transparent conductive material, which is any one of a transparent conductive metal electrode layer, a transparent conductive hydrogel electrode layer or a transparent conductive oxide electrode layer.

[0037] In some specific embodiments, the transparent conductive metal electrode layer is a silver nanowire layer; the transparent conductive hydrogel electrode layer is a polyacrylamide hybrid hydrogel layer; and the transparent conductive oxide electrode layer is an indium tin oxide layer.

[0038] In some specific embodiments, the bottom adhesive layer is any one of a transparent organic coating, a transparent inorganic coating, and a transparent polymer coating.

[0039] In some specific embodiments, the transparent polymer coating is a transparent PET tape or a transparent VHB tape.

[0040] The flexible, ultra-thin, non-contact screen sensor is manufactured by the following steps:

[0041] S1, disposing a transparent conductive material on one side of the transparent electret film material to form a conductive sensing layer;

[0042] S2, performing polarization treatment on the side of the transparent electret film material where the conductive sensing layer is not provided, to obtain a surface polarization layer with distributed charges;

[0043] S3, adhering the bottom adhesive layer to one side of the conductive sensing layer in step S2, to obtain a transparent non-contact screen sensor having a three-layer structure of surface polarization layer / conductive sensing layer / bottom adhesive layer.

[0044] In some specific embodiments, the conductive induction layer described in step S1 is to arrange the transparent conductive material on one side of the transparent electret film material by thermal evaporation coating, magnetron sputtering or coating; the polarization treatment described in step S2 is to use corona polarization, thermal polarization, ion implantation or electron beam implantation to distribute charges on the transparent electret film material to form a surface polarization layer, and the conductive induction layer generates induced charges accordingly.

[0045] In some specific embodiments, the screen sensors prepared in step S3 are combined into a cross-shaped or other shaped array as required to prepare a flexible, ultra-thin array-type non-contact screen sensor. When an object approaches the screen sensor, the electrostatic induction effect will change the induced charge in the conductive sensing layer of the screen sensor, and then a corresponding induced current will be generated in the external load circuit. By measuring the output voltage at both ends of the external load, the position or shape of the external object can be determined.

[0046] The raw materials and equipment used in the present invention are all conventional raw materials and equipment in the art. In the following embodiments, raw materials or processing techniques, unless otherwise specified, are all conventional commercially available raw materials or conventional processing techniques in the art.

[0047] Example 1

[0048] 1) First, a transparent polylactic acid film (light transmittance: 90%) with a length × width of 5 cm × 5 cm and a thickness of 15 μm is selected, and a layer of silver nanowires is coated on one surface of the transparent polylactic acid film using a coating machine to obtain a transparent polylactic acid film coated with silver nanowires, and the silver nanowire layer is used as a conductive sensing layer;

[0049] 2) polarizing the transparent polylactic acid film coated with silver nanowires at a voltage of 10 kV for 3 min using a corona polarization method to obtain a transparent polylactic acid film with distributed charges;

[0050] 3) A transparent PET tape is adhered to one side of the silver nanowire to prepare a transparent electret-based screen sensor with a three-layer structure of polylactic acid / silver nanowire / PET tape, such as Figure 1 As shown;

[0051] 4) The three-layer structure of the transparent electret-based screen sensor is cut into 0.5 cm wide strips, and each strip is connected at 0.5 cm intervals to form a 5×4 vertical cross array, such as Figure 2 As shown, a screen sensor is prepared that can be used to recognize three-dimensional contours.

[0052] When an object approaches the screen sensor, the electrostatic induction effect will change the induced charge in the conductive sensing layer of the screen sensor, and then a corresponding induced current will be generated in the external load circuit. By measuring the output voltage across the external load, the position or shape of the external object can be determined.

[0053] Example 2

[0054] 1) introducing a PDMS mixture containing 2 wt% SiO2 nanoparticles into a mold and curing it to obtain a transparent PDMS mixture film with a length×width of 1.5 cm×1.5 cm and a thickness of 0.3 mm;

[0055] 2) Add 1.6g of acrylamide powder and 1.2g of LiCl to a mixed solution consisting of 2ml of deionized water and 8ml of ethylene glycol. Then, dissolve 0.01g of N,N-methylenebisacrylamide and 0.05g of ammonium persulfate in the above mixture to form a liquid hydrogel. Add N,N,N',N'-tetramethyleneethylenediamine and coat it on one surface of the transparent PDMS mixture film of step 1) using a coater, and let it stand at room temperature to obtain a transparent PDMS mixture film covered with polyacrylamide hybrid hydrogel, and the polyacrylamide hybrid hydrogel layer serves as a conductive sensing layer;

[0056] 3) polarizing the transparent PDMS mixture film covered with the polyacrylamide hybrid hydrogel at 100° C. and an electric field strength of 3.75 kV / mm for 60 min using a contact polarization method to obtain a transparent PDMS mixture film with distributed charges;

[0057] 4) A transparent VHB tape (3M VHB 9469) was adhered to the bottom of one side of the polyacrylamide hybrid hydrogel to form a transparent electret-based screen sensor with a three-layer structure of SiO2-PDMS / polyacrylamide hybrid hydrogel / VHB tape.

[0058] 5) Repeat the above steps 1-4 to prepare four identical screen sensors, adhere the screen sensors to the four corners of the desktop, detect whether there are objects approaching in the four directions, and perform positioning sensing on their positions.

[0059] When an object approaches the screen sensor, the electrostatic induction effect will change the induced charge in the conductive sensing layer of the screen sensor, and then a corresponding induced current will be generated in the external load circuit. By measuring the output voltage across the external load, the position or shape of the external object can be determined.

[0060] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A flexible, ultra-thin, non-contact screen sensor, characterized in that: It has a three-layer structure, including: surface polarization layer, conductive induction layer and bottom adhesion layer. The surface polarization layer is distributed with charges, The conductive induction layer is arranged between the surface polarization layer and the bottom adhesion layer, and leads out a wire to connect an external load circuit, generating a corresponding induced current in the external load circuit. The conductive sensing layer is adhered to one side of the bottom adhesive layer, and the target device is adhered to the other side; The surface polarization layer, the conductive sensing layer and the bottom adhesion layer of the sensor are all made of transparent materials.

2. A flexible, ultra-thin, non-contact screen sensor according to claim 1, characterized in that: The thickness of the surface polarization layer is 0.001-1 mm, the thickness of the conductive induction layer is 0.1-1 μm, and the thickness of the bottom adhesion layer is 0.01-0.1 mm.

3. The flexible, ultra-thin, non-contact screen sensor according to claim 1, characterized in that: The surface polarization layer is made of a transparent electret film material, which is any one of a transparent polylactic acid film layer, a transparent polypropylene film layer, a transparent fluorinated ethylene propylene copolymer film layer or other transparent electret film layers.

4. The flexible, ultra-thin, non-contact screen sensor according to claim 3, characterized in that: The transparent electret film material is obtained by doping a transparent base material with polar particles; the transparent base material is polydimethylsiloxane or platinum silicone Ecoflex, and the polar particles are silicon dioxide or polytetrafluoroethylene.

5. The flexible, ultra-thin non-contact screen sensor according to claim 1, characterized in that: The conductive sensing layer is made of a transparent conductive material, which is any one of a transparent conductive metal electrode layer, a transparent conductive hydrogel electrode layer or a transparent conductive oxide electrode layer.

6. The flexible, ultra-thin, non-contact screen sensor according to claim 5, characterized in that: The transparent conductive metal electrode layer is a silver nanowire layer; the transparent conductive hydrogel electrode layer is a polyacrylamide hybrid hydrogel layer; and the transparent conductive oxide electrode layer is an indium tin oxide layer.

7. The flexible, ultra-thin, non-contact screen sensor according to claim 1, characterized in that: The bottom surface adhesion layer is any one of a transparent organic coating, a transparent inorganic coating, and a transparent polymer coating.

8. A method for preparing a flexible, ultra-thin non-contact screen sensor as claimed in any one of claims 1 to 7, characterized in that: The steps include: S1, disposing a transparent conductive material on one side of the transparent electret film material to form a conductive sensing layer; S2, performing polarization treatment on the side of the transparent electret film material where the conductive sensing layer is not provided, to obtain a surface polarization layer with distributed charges; S3, adhering the bottom adhesive layer to one side of the conductive sensing layer in step S2, to obtain a transparent non-contact screen sensor having a three-layer structure of surface polarization layer / conductive sensing layer / bottom adhesive layer.

9. The flexible, ultra-thin, non-contact screen sensor according to claim 8, characterized in that: The conductive sensing layer described in step S1 is a transparent conductive material disposed on one side of the transparent electret film material by thermal evaporation coating, magnetron sputtering or coating; The polarization treatment described in step S2 is performed by corona polarization, thermal polarization, ion implantation or electron beam implantation to distribute electric charges on the transparent electret film material.

10. The flexible, ultra-thin, non-contact screen sensor according to claim 8, characterized in that: The screen sensors obtained in step S3 are combined into a cross-shaped array or other shaped arrays as required to prepare a flexible, ultra-thin array-type non-contact screen sensor.

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