Embedded flexible sensor and manufacturing method thereof

Abstract

The application provides an embedded flexible sensor and a manufacturing method thereof. The embedded flexible sensor comprises at least one flexible sensing element, a first substrate, an adhesive layer and a second substrate which are stacked in sequence along the thickness direction. The flexible sensing element is arranged in the adhesive layer. The first substrate comprises at least one first circuit layer and at least one first conductive hole. One end of the first conductive hole is electrically connected to the first circuit layer, and the other end is electrically connected to the flexible sensing element. The second substrate comprises at least one second circuit layer and at least one second conductive hole. One end of the second conductive hole is electrically connected to the second circuit layer, and the other end is electrically connected to the flexible sensing element. The flexible sensing element is arranged in the stacked first flexible sensing layer and second flexible sensing layer, which is beneficial to the miniaturization and thinning of the flexible sensor and the improvement of the sensitivity.

Description

Technical Field

[0001] This invention relates to the field of flexible sensors, and more particularly to an embedded flexible sensor and its manufacturing method. Background Technology

[0002] As portable electronic products trend towards miniaturization, recent advancements have primarily relied on technologies such as high integration, miniaturization, and micro-scale components, as well as the integration of passive and active components within multilayer substrates. Currently, directly mounting flexible sensors onto circuit boards does not achieve the desired thinness. Summary of the Invention

[0003] In view of this, it is necessary to provide an embedded flexible sensor and its manufacturing method to solve the above problems.

[0004] This application discloses an embedded flexible sensor, comprising at least one flexible sensing element and a first substrate, an adhesive layer, and a second substrate stacked sequentially along the thickness direction. The flexible sensing element is disposed within the adhesive layer and is covered by the first substrate, the adhesive layer, and the second substrate. The flexible sensing element includes a first flexible sensing layer and a second flexible sensing layer stacked along the thickness direction, with the first flexible sensing layer located on the side of the second flexible sensing layer away from the second substrate. The first substrate includes at least one first circuit layer and at least one first conductive hole, with one end of the first conductive hole electrically connected to the first circuit layer and the other end electrically connected to the first flexible sensing layer. The second substrate includes at least one second circuit layer and at least one second conductive hole, with one end of the second conductive hole electrically connected to the second circuit layer and the other end electrically connected to the second flexible sensing layer.

[0005] This application also proposes a method for fabricating an embedded flexible sensor, comprising the following steps:

[0006] A first substrate and a second substrate are provided. The first substrate includes at least one first circuit layer and at least one first conductive hole, one end of the first conductive hole is electrically connected to the first circuit layer, and the other end is exposed on a surface of the first substrate. The second substrate includes at least one second circuit layer and at least one second conductive hole, one end of the second conductive hole is electrically connected to the second circuit layer, and the other end is exposed on a surface of the second substrate.

[0007] At least one first flexible sensing layer is provided on one side of the first substrate, and the first conductive hole is electrically connected to the first flexible sensing layer from one exposed end of the first substrate; at least one second flexible sensing layer is provided on one side of the second substrate, and the second conductive hole is electrically connected to the second flexible sensing layer from one exposed end of the second substrate.

[0008] An adhesive layer is provided, the adhesive layer having at least one through hole, the adhesive layer being disposed between the first substrate and the second substrate, and the first flexible sensing layer and the second flexible sensing layer being disposed opposite to each other corresponding to the through hole;

[0009] The first substrate, the adhesive layer, and the second substrate are pressed together along the thickness direction. The first flexible sensing layer and the second flexible sensing layer overlap through the through-hole to form a flexible sensing element. The adhesive layer covers the flexible sensing element.

[0010] The embedded flexible sensor of the present invention achieves embedded flexible sensor by forming a first circuit layer and a first conductive hole in a first substrate, a second circuit layer and a second conductive hole in a second substrate, and a flexible sensing element in an adhesive layer, thereby facilitating the thinning and miniaturization of electronic products. Furthermore, by setting the flexible sensing element as a stacked first flexible sensing layer and a second flexible sensing layer, the embedded flexible sensor exhibits high sensitivity. Attached Figure Description

[0011] Figure 1 This is a cross-sectional schematic diagram of a copper-clad laminate provided in an embodiment of this application.

[0012] Figure 2 It is at Figure 1 The diagram shows a cross-section of a copper-clad laminate after blind vias have been created.

[0013] Figure 3 It is at Figure 2 The diagram shows a cross-section of the first conductive hole formed by printing conductive paste inside the blind hole.

[0014] Figure 4 It is at Figure 3 The diagram shows a cross-sectional view of the first copper layer surface after the first metal coating has been applied.

[0015] Figure 5 It is at Figure 4 The diagram shows a cross-sectional view of the first metal coating surface after the formation of the first blackening layer.

[0016] Figure 6 It is Figure 5 The diagram shows a cross-sectional view of the intermediate obtained after the first copper layer, the first metal coating, and the first blackening layer are patterned to form the first circuit layer.

[0017] Figure 7 It is at Figure 6 The diagram shows a process for setting a protective layer on the surface of the intermediate.

[0018] Figure 8 It is at Figure 7The diagram shows a cross-sectional view of the first substrate obtained after a protective layer is applied to the surface of the intermediate.

[0019] Figure 9 It is at Figure 8 The diagram shows a cross-sectional view of the first substrate surface after the first flexible sensing layer has been applied.

[0020] Figure 10 It is at Figure 8 The diagram shows a process for setting a first flexible sensing layer on the surface of a first substrate.

[0021] Figure 11 It is Figure 8 The diagram shows the process of laminating the first substrate with the adhesive layer and the second substrate.

[0022] Figure 12 This is a schematic diagram of the process of simultaneously fabricating a first substrate and a first substrate according to one embodiment of this application.

[0023] Figure 13 This is a cross-sectional schematic diagram of an embedded flexible sensor provided in an embodiment of this application.

[0024] Figure 14 yes Figure 13 The diagram shows an enlarged view of the flexible sensing element.

[0025] Explanation of main component symbols

[0026] Embedded flexible sensor 100, through hole 42

[0027] Copper-clad laminate 10 Second substrate 50

[0028] First insulating layer 101 Second insulating layer 51

[0029] First copper layer 102 Second adhesive layer 52

[0030] Blind hole 103 Second cover film 53

[0031] First conductive vias 11, 11' Second circuit layer 54

[0032] First metal coating 12 Second copper layer 541

[0033] First blackening layer 13 Second metal coating 542

[0034] First line layer 15, 15' Second blackening layer 543

[0035] Intermediate body 20 Second conductive hole 55

[0036] Protective layer 22 Second flexible sensing layer 60

[0037] First adhesive layer 221 Second body 61

[0038] First covering film 222 Second protrusion 62

[0039] First substrate 25 second recess 63

[0040] First flexible sensing layer 30, 30' Flexible sensing element 70

[0041] First body 31 Glass substrate 110

[0042] The first protrusion 32 and the third substrate 120

[0043] First recess 33 thickness direction N

[0044] Adhesive layer 40, pressure-bearing area P

[0045] The following detailed embodiments will further illustrate the technical solution of the present invention in conjunction with the above-mentioned accompanying drawings. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0048] Please see Figures 1 to 14 A preferred embodiment of the present invention discloses a method for manufacturing an embedded flexible sensor 100, which includes the following steps:

[0049] Step S1, please refer to Figure 8 A first substrate 25 is provided, the first substrate 25 includes a first circuit layer 15 and a first conductive hole 11, the first conductive hole 11 being electrically connected to the first circuit layer 15.

[0050] In some embodiments, the first substrate 25 has a thickness direction N. The first substrate 25 may include a first insulating layer 101, a first adhesive layer 221 and a first cover film 222 stacked sequentially along the thickness direction N. The first circuit layer 15 is disposed in the first adhesive layer 221. The first conductive hole 11 is disposed through the first insulating layer 101. One end of the first conductive hole 11 is electrically connected to the first circuit layer 15, and the other end is exposed from the surface of the first insulating layer 101 away from the first adhesive layer 221.

[0051] The first circuit layer 15 includes a first copper layer 102, a first metal coating 12, and a first blackening layer 13, which are sequentially stacked along the thickness direction N. In other embodiments, the first circuit layer 15 may include only the first copper layer 102 and the first blackening layer 13, without including the first metal coating 12.

[0052] Please see Figures 1 to 8 The first substrate 25 can be manufactured by, but is not limited to, the following methods, specifically including the following steps:

[0053] Step S11, please refer to Figure 1 A copper-clad laminate 10 is provided, the copper-clad laminate 10 including a first insulating layer 101 and a first copper layer 102 stacked N times along the thickness direction.

[0054] Step S12, please refer to Figure 2 At least one blind hole 103 is formed through the copper-clad laminate 10 along the thickness direction N.

[0055] Specifically, the blind hole 103 can be opened by means of, but not limited to, laser drilling.

[0056] Step S13, please refer to Figure 3 The first conductive hole 11 is formed by vacuum printing conductive paste into the blind hole 103 to plug the hole.

[0057] The conductive paste can be silver paste or copper paste, etc.

[0058] Step S14, please refer to Figure 4 A first metal coating 12 is provided on the surface of the first copper layer 102 opposite to the first insulating layer 101, and the first metal coating 12 comprises elemental metal powder.

[0059] Specifically, step S14 includes:

[0060] A coating is provided, the coating containing metal ions, a reducing agent and a binder, wherein the metal ions include at least one selected from silver ions, copper ions and iron ions, and the binder includes at least one selected from epoxy resins;

[0061] The coating is applied to the surface of the first copper layer 102 away from the first insulating layer 101, and then baked to allow the metal ions to react with the reducing agent, thereby reducing the metal ions to elemental metal powder.

[0062] Step S15, please refer to Figure 5 The metal elemental powder on the side of the first metal coating 12 away from the first copper layer 102 is oxidized to form the first blackening layer 13.

[0063] Specifically, an oxidizing agent is sprayed onto the surface of the first metal coating 12 opposite to the first copper layer 102, causing some of the elemental metal powder within the first metal coating 12 to be oxidized into metal oxides, thereby forming the first blackened layer 13. The oxidizing agent may be at least one of potassium sulfide solution, potassium thiosulfate, potassium polysulfide solution, and nitric acid solution.

[0064] Understandably, in other embodiments, the first blackening layer 13 can also be formed by directly oxidizing a portion of the copper element in the first copper layer 102 that is away from the first insulating layer 101.

[0065] Compared to the traditional method of directly oxidizing the first copper layer 102 to form a blackened layer, the method of setting the first metal coating 12 and oxidizing the first metal coating 12 to obtain the first blackened layer 13 is beneficial to avoid making the first copper layer 102 thinner, thereby affecting the conductivity of the subsequent first circuit layer 15. Moreover, the first blackened layer 13 formed by oxidation is uniform and dense with low surface roughness, which can improve the conductivity of the subsequent first circuit layer 15 to a certain extent.

[0066] Step S16, please refer to Figure 6 The first copper layer 102, the corresponding first metal coating 12 and the first blackening layer 13 are simultaneously patterned to form the first circuit layer 15, and the first conductive hole 11 is electrically connected to the first circuit layer 15 to obtain the intermediate body 20.

[0067] Specifically, a photosensitive dry film can be attached to the surface of the first blackened layer 13, and then exposed, developed, etched, and the film removed to form the first circuit layer 15.

[0068] Step S17, please refer to Figure 7 and Figure 8 A protective layer 22 is pressed onto one side of the intermediate body 20 where the first circuit layer 15 is located. The protective layer 22 includes a first adhesive layer 221 and a first cover film 222 stacked together. The first adhesive layer 221 faces the first insulating layer 101 and covers the first circuit layer 15.

[0069] The first insulating layer 101 and the first covering film 222 are both made of transparent and stretchable materials, such as polyimide (PI), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). In this embodiment, both the first insulating layer 101 and the first covering film 222 are made of polyethylene naphthalate.

[0070] The first adhesive layer 221 is a transparent adhesive layer with elastic properties. Specifically, the material of the first adhesive layer 221 includes either polydimethylsiloxane (PDMS) or polyethylene terephthalate.

[0071] For step S2, please refer to [link / reference]. Figure 9 A first flexible sensing layer 30 is disposed on the surface of the first insulating layer 101 opposite to the first adhesive layer 221, and the first flexible sensing layer 30 is electrically connected to the first conductive hole 11.

[0072] The first flexible sensing layer 30 includes a first body 31, on the side of the first body 31 facing away from the first insulating layer 101, a first protrusion 32 and a first recess 33 are alternately arranged in a direction perpendicular to the thickness N.

[0073] The first flexible sensing layer 30 is mainly composed of a composite material of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) (denoted as PEDOT:PSS), and may also include various additives that can modify it, such as metal salts, metal oxide particles, graphene, carbon nanotubes, silver nanowires, etc. PEDOT:PSS is a conductive polymer with high conductivity, high flexibility, good chemical stability and high transparency. In addition, it has strong processability and can be modified by adding different additives according to functional requirements.

[0074] In some embodiments, please refer to Figure 10 Step S2 specifically includes:

[0075] Step S21: The PEDOT:PSS solution is vacuum printed onto the glass substrate 110 to form the first flexible sensing layer 30.

[0076] The glass substrate 110 has multiple cylindrical holes with a width of 25μm to 50μm and a depth of 10μm to 30μm, and the multiple cylindrical holes are arranged in a partitioned manner.

[0077] Step S22: Immerse the glass substrate 110 with the first flexible sensing layer 30 in sulfuric acid for 10 minutes at room temperature, and then dry it at 120°C for 10 minutes.

[0078] After the glass substrate 110 is soaked in sulfuric acid, the chemical structure of the first flexible sensing layer 30 changes, thereby reducing the hydrogen bond adhesion between it and the glass substrate 110 and reducing transfer defects.

[0079] Step S23: The first flexible sensing layer 30 is attached to the side of the first substrate 25 where the first insulating layer 101 is located, and the first flexible sensing layer 30 is transferred from the glass substrate 110 to the first substrate 25 by using the van der Waals force between the two.

[0080] Step S3, please refer to Figure 11 An adhesive layer 40 and a second substrate 50 are provided. The adhesive layer 40 is disposed between the first substrate 25 and the second substrate 50. A second flexible sensing layer 60 is provided on one side surface of the second substrate 50. A through hole 42 is provided through the adhesive layer 40.

[0081] The second substrate 50 and the first substrate 25 have substantially the same structure. The second substrate 50 includes a second insulating layer 51, a second adhesive layer 52, and a second cover film 53, which are sequentially stacked along the thickness direction N. A second circuit layer 54 is provided in the second adhesive layer 52. At least one second conductive hole 55 is provided through the second insulating layer 51. One end of the second conductive hole 55 is electrically connected to the second circuit layer 54, and the other end is exposed from the surface of the second insulating layer 51 away from the second adhesive layer 52. The second circuit layer 54 includes a second copper layer 541, a second metal coating 542, and a second blackening layer 543, which are sequentially stacked along the thickness direction N.

[0082] Understandably, the second substrate 50 can be manufactured using a method that is substantially the same as that used for the first substrate 25, and will not be described in detail here.

[0083] The second flexible sensing layer 60 has a structure that is substantially the same as that of the first flexible sensing layer 30. The second flexible sensing layer 60 is electrically connected to the second conductive hole 55. The second flexible sensing layer 60 includes a second body 61 connected to the second insulating layer 51. On the side of the second body 61 facing away from the second insulating layer 51, a plurality of second protrusions 62 and second recesses 63 are alternately provided in a direction perpendicular to the thickness.

[0084] Both the second insulating layer 51 and the second covering film 53 are made of transparent and stretchable materials, such as polyimide (PI), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). In this embodiment, both the second insulating layer 51 and the second covering film 53 are made of polyethylene naphthalate.

[0085] The adhesive layer 40 and the second adhesive layer 52 are transparent adhesive layers with elasticity. Specifically, the materials of the adhesive layer 40 and the second adhesive layer 52 include polydimethylsiloxane (PDMS) or polyethylene terephthalate.

[0086] In this embodiment, the first flexible sensing layer 30 and the second flexible sensing layer 60 are made of the same material.

[0087] In some embodiments, please refer to Figure 12 Alternatively, a third substrate 120 can be fabricated first. The third substrate 120 is provided with a plurality of first circuit layers 11' and corresponding first conductive holes 15'. A first flexible sensing layer 30' is provided in each of the first conductive holes 15'. After punching and cutting, a single first substrate 25 and a second substrate 50 can be obtained simultaneously.

[0088] For step S4, please refer to [link / reference]. Figure 13 Along the thickness direction N, after the PIN is aligned, the first substrate 25, the adhesive layer 40 and the second substrate 50 are pressed together. The first flexible sensing layer 30 and the second flexible sensing layer 60 are overlapped and housed in the through hole 42 to form a flexible sensing element 70. The adhesive layer 40 covers the flexible sensing element 70 to obtain an embedded flexible sensor 100.

[0089] Because PSS is hydrophilic, the flexible sensor 70, with PEDOT:PSS as its main material, is highly susceptible to environmental humidity. The absorption of water molecules can cause the PSS shell to expand, increasing the distance between adjacent PEDOT-rich cores, thereby increasing resistance and interfering with measurement accuracy. In this application, by covering the flexible sensor 70 with the first substrate 25 and the second substrate 50 on opposite sides, the flexible sensor 70 is embedded in a circuit board. This suppresses the resistance change caused by the absorption of environmental moisture by sulfonate groups in the PEDOT:PSS material, effectively improving the measurement accuracy and reproducibility of the flexible sensor.

[0090] In some embodiments, please refer to the following: Figure 13 and Figure 14 The first protrusion 32 of the first flexible sensing layer 30 and the second protrusion 62 of the second flexible sensing layer 60 are staggered, that is, the first protrusion 32 corresponds to the second recess 63, and the second protrusion 62 corresponds to the first recess 33, thereby forming a biomimetic interlocking structure between the first flexible sensing layer 30 and the second flexible sensing layer 60. By embedding the flexible sensing element 70, designing it with a special material, and forming an interlocking structure, the embedded flexible sensor 100 has a thin overall structure and high sensitivity to lateral strain, achieving a sensitivity of 15.1 kPa under low pressure (<10 kPa). -1 .

[0091] In some embodiments, please refer to the following: Figure 13 and Figure 14 In the first flexible sensing layer 30, the thickness of the first body 31 is 10μm to 15μm, the length a is 300μm to 500μm, and the width b is 300μm to 500μm. The height of the first protrusion 32 is 10μm to 30μm, and the width is 25μm to 50μm. The total thickness of the first flexible sensing layer 30 is 20μm to 45μm. The dimensions of the second flexible sensing layer 60 are the same as those of the first flexible sensing layer 30. The total thickness c of the flexible sensing element 70 is 38μm to 90μm, and the length and width of the pressure-receiving area P corresponding to each flexible sensing element 70 are 1000μm to 1500μm.

[0092] The resistance value R of the embedded flexible sensor 100 can be calculated using the following formula:

[0093] R = ρL / S = ρc / (ab)

[0094] Wherein, ρ is the resistivity of the material of the flexible sensing element 70, L is the line length, S is the cross-sectional area, a is the length, b is the width, and c is the thickness. In this application, the resistance of the embedded flexible sensor 100 can be adjusted by controlling the dimensions of the flexible sensing element 70.

[0095] Since both the first substrate 25 and the second substrate 50 are made of transparent material, the embedded flexible sensor 100 is entirely transparent, with a light transmittance of up to 90%. Furthermore, because PEDOT:PSS itself has strong mechanical properties and high ductility, the adhesive layer 40 effectively solves the problem of excess adhesive when pressing the upper and lower transparent circuit boards together. Further, by setting the first blackening layer 13 and the second blackening layer 543, the overall visual light transmittance can be improved, and the bonding strength between the first circuit layer 15 and the first cover film 222, and between the second circuit layer 54 and the second cover film 53 can be increased. Therefore, the embedded flexible sensor 100 can be widely used in transparent wearable devices.

[0096] It is understood that the embedded flexible sensor 100 described in this application is only an example with two circuit boards. In other embodiments, it may also be multi-layered.

[0097] Please see Figure 13 and Figure 14 This application also provides an embedded flexible sensor 100 manufactured using the above-described method. The embedded flexible sensor 100 includes a first substrate 25, an adhesive layer 40, and a second substrate 50 stacked sequentially along the thickness direction N. At least one flexible sensing element 70 is disposed within the adhesive layer 40. The first substrate 25 includes a first circuit layer 15 and a first conductive hole 11. One end of the first conductive hole 11 is electrically connected to the first circuit layer 15, and the other end is electrically connected to one side of the flexible sensing element 70. The second substrate 50 includes a second circuit layer 54 and a second conductive hole 55. One end of the second conductive hole 55 is electrically connected to the second circuit layer 54, and the other end is electrically connected to the other side of the flexible sensing element 70.

[0098] The flexible sensing element 70 includes a first flexible sensing layer 30 and a second flexible sensing layer 60 stacked along the thickness direction N. The first flexible sensing layer 30 is located on the side of the second flexible sensing layer 60 away from the second substrate 50. The first flexible sensing layer 30 is electrically connected to the first conductive hole 11, and the second flexible sensing layer 60 is electrically connected to the second conductive hole 55. The first flexible sensing layer 30 includes a first body 31 connected to one side of the first substrate 25. On the side of the first body 31 facing away from the first substrate 25, a plurality of first protrusions 32 and first recesses 33 are alternately arranged in a direction perpendicular to the thickness direction N. The second flexible sensing layer 60 includes a second body 61 connected to one side of the second substrate 50. On the side of the second body 61 facing away from the second substrate 50, a plurality of second protrusions 62 and second recesses 63 are alternately arranged in a direction perpendicular to the thickness direction N.

[0099] In some embodiments, the first protrusion 32 of the first flexible sensing layer 30 and the second protrusion 62 of the second flexible sensing layer 60 are staggered, with the first protrusion 32 corresponding to the second recess 63 and the second protrusion 62 corresponding to the first recess 33. This allows the first flexible sensing layer 30 and the second flexible sensing layer 60 to overlap and form a biomimetic interlocking structure, enabling the embedded flexible sensor 100 to achieve a sensitivity of 15.1 kPa under low pressure (<10 kPa). -1 .

[0100] The flexible sensing element 70 is mainly made of a composite material of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) (denoted as PEDOT:PSS), and may also include various additives that can modify it, such as metal salts, metal oxide particles, graphene, carbon nanotubes, silver nanowires, etc.

[0101] The first substrate 25 and the second substrate 50 have substantially the same structure. Specifically, the first substrate 25 has a thickness direction N, and the first substrate 25 includes a first insulating layer 101, a first adhesive layer 221 and a first cover film 222 stacked sequentially along the thickness direction N. The first circuit layer 15 is disposed in the first adhesive layer 221. One end of the first conductive hole 11 is electrically connected to the first circuit layer 15, and the other end is exposed from the surface of the first insulating layer 101 away from the first adhesive layer 221 to be electrically connected to the first flexible sensing layer 30.

[0102] The first circuit layer 15 includes a first copper layer 102 and a first blackening layer 13 stacked sequentially along the thickness direction N. In some embodiments, a first metal coating 12 may also be provided between the first copper layer 102 and the first blackening layer 13.

[0103] The second substrate 50 includes a second insulating layer 51, a second adhesive layer 52 and a second cover film 53 stacked together. A second circuit layer 54 is provided in the second adhesive layer 52. At least one second conductive hole 55 is provided through the second insulating layer 51. One end of the second conductive hole 55 is electrically connected to the second circuit layer 54, and the other end is exposed from the surface of the second insulating layer 51 away from the second adhesive layer 52 to be electrically connected to the second flexible sensing layer 60.

[0104] The second circuit layer 54 includes a second copper layer 541 and a second blackening layer 543 stacked sequentially. In some embodiments, a second metal coating 542 may be provided between the second copper layer 541 and the second blackening layer 543.

[0105] In this embodiment, the first insulating layer 101, the first covering film 222, the second insulating layer 51, and the second covering film 53 are all made of transparent material. Specifically, in this embodiment, the first insulating layer 101, the first covering film 222, the second insulating layer 51, and the second covering film 53 are all made of polyethylene naphthalate.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above as a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An embedded flexible sensor, characterized in that, The system includes at least one flexible sensor and a first substrate, an adhesive layer, and a second substrate stacked sequentially along the thickness direction. The flexible sensor is disposed within the adhesive layer and covered by the first substrate, the adhesive layer, and the second substrate. The flexible sensor includes a first flexible sensing layer and a second flexible sensing layer stacked along the thickness direction. The first flexible sensing layer is located on the side of the second flexible sensing layer away from the second substrate. The first flexible sensing layer includes a first protrusion and a first recess alternately arranged perpendicular to the thickness direction. The second flexible sensing layer includes a second protrusion and a second recess alternately arranged perpendicular to the thickness direction. The first protrusion and the second recess are correspondingly arranged, and the first recess and the second protrusion are correspondingly arranged, so that the first flexible sensing layer and the second flexible sensing layer are interlocked in the thickness direction. The first substrate includes at least one first circuit layer and at least one first conductive hole. One end of the first conductive hole is electrically connected to the first circuit layer, and the other end is electrically connected to the first flexible sensing layer. The second substrate includes at least one second circuit layer and at least one second conductive hole. One end of the second conductive hole is electrically connected to the second circuit layer, and the other end is electrically connected to the second flexible sensing layer.

2. The embedded flexible sensor as described in claim 1, characterized in that, The first substrate further includes a first insulating layer, a first adhesive layer and a first cover film stacked sequentially along the thickness direction, the first circuit layer is disposed in the first adhesive layer, and the first conductive hole penetrates the first insulating layer; The second substrate further includes a second insulating layer, a second adhesive layer and a second cover film stacked sequentially along the thickness direction, the second circuit layer is disposed in the second adhesive layer and the second conductive hole penetrates the second insulating layer; The adhesive layer bonds the first insulating layer and the second insulating layer.

3. The embedded flexible sensor as described in claim 2, characterized in that, The first insulating layer, the first covering film, the second insulating layer, and the second covering film are all made of transparent material.

4. The embedded flexible sensor as described in claim 3, characterized in that, The flexible sensing element is made of poly(dioxyethylthiophene) and polystyrene sulfonic acid, and the first insulating layer, the first covering film, the second insulating layer and the second covering film are all made of polyethylene naphthalate.

5. The embedded flexible sensor as described in claim 1, characterized in that, The first circuit layer includes a first copper layer and a first blackening layer stacked on the side of the first copper layer away from the flexible sensor. The second circuit layer includes a second copper layer and a second blackening layer stacked on the side of the second copper layer away from the flexible sensor.

6. A method for manufacturing an embedded flexible sensor, characterized in that, Includes the following steps: A first substrate and a second substrate are provided. The first substrate includes at least one first circuit layer and at least one first conductive hole, one end of the first conductive hole is electrically connected to the first circuit layer, and the other end is exposed on a surface of the first substrate. The second substrate includes at least one second circuit layer and at least one second conductive hole, one end of the second conductive hole is electrically connected to the second circuit layer, and the other end is exposed on a surface of the second substrate. At least one first flexible sensing layer is disposed on one side of the first substrate, and the first conductive hole is electrically connected to the first flexible sensing layer from one exposed end of the first substrate; at least one second flexible sensing layer is disposed on one side of the second substrate, and the second conductive hole is electrically connected to the second flexible sensing layer from one exposed end of the second substrate; the first flexible sensing layer includes a first protrusion and a first recess alternately arranged perpendicular to the thickness direction, and the second flexible sensing layer includes a second protrusion and a second recess alternately arranged perpendicular to the thickness direction. An adhesive layer is provided, the adhesive layer having at least one through hole, the adhesive layer being disposed between the first substrate and the second substrate, and the first flexible sensing layer and the second flexible sensing layer being disposed opposite to each other corresponding to the through hole; The first substrate, the adhesive layer, and the second substrate are pressed together along the thickness direction. The first protrusion and the second concave portion correspond to each other, and the first concave portion and the second protrusion overlap to form an interlocking structure. The first flexible sensing layer and the second flexible sensing layer overlap through the through hole to form a flexible sensing element. The adhesive layer covers the flexible sensing element.

7. The manufacturing method as described in claim 6, characterized in that, The step of "depositing at least one first flexible sensing layer on one side of the first substrate" includes: The first flexible sensing layer is formed by coating a mixed solution of poly(dioxyethylthiophene) and polystyrene sulfonic acid onto a glass substrate. The glass substrate was immersed in sulfuric acid and then dried. The first substrate is attached to the dried first flexible sensing layer, and the first flexible sensing layer is transferred to the first substrate using van der Waals forces.

8. The manufacturing method as described in claim 6, characterized in that, The method for manufacturing the first substrate includes the following steps: A copper-clad laminate is provided, the copper-clad laminate comprising a first insulating layer and a first copper layer stacked along the thickness direction, and the copper-clad laminate having a first conductive hole through it; The portion of the first copper layer that is away from the first insulating layer is oxidized to form a first blackening layer. The first copper layer and the first blackening layer are patterned to form the first circuit layer, and the first circuit layer is electrically connected to the first conductive hole to obtain the first substrate.

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