Embedded flexible sensor and manufacturing method thereof

Abstract

The invention provides an embedded flexible sensor and a manufacturing method thereof.The embedded flexible sensor comprises at least one flexible sensing part, a first substrate, a bonding layer and a second substrate, the first substrate, the bonding layer and the second substrate are sequentially stacked in the thickness direction, the flexible sensing part is arranged in the bonding layer, the first substrate comprises at least one first circuit layer and at least one first conductive hole, and the second substrate comprises at least one second circuit layer and at least one second conductive hole. One end of the first conductive hole is electrically connected with the first circuit layer, the other end of the first conductive hole is electrically connected with the flexible sensing piece, 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 with the second circuit layer, and the other end of the second conductive hole is electrically connected with the flexible sensing piece. According to the flexible sensing element, the first flexible sensing layer and the second flexible sensing layer which are stacked are embedded, so that the miniaturization and thinning of the flexible sensor are facilitated, and the sensitivity is improved.

Description

Technical Field

[0001] The present invention relates to the field of flexible sensors, and in particular to an embedded flexible sensor and a manufacturing method thereof. Background Art

[0002] As portable electronic products develop towards miniaturization, they have mainly relied on the development of high-integration, miniaturization or micro-fine technology of components in recent years, as well as the application of passive components and active components built into multi-layer substrates. Currently, the industry cannot achieve ideal thinness by directly mounting flexible sensors on circuit boards. Summary of the invention

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

[0004] The present application proposes an embedded flexible sensor, comprising at least one flexible sensing element and a first substrate, an adhesive layer and a second substrate stacked in sequence along a thickness direction, wherein the flexible sensing element is arranged in the adhesive layer and is covered by the first substrate, the adhesive layer and the second substrate, wherein the flexible sensing element comprises a first flexible sensing layer and a second flexible sensing layer stacked along a thickness direction, wherein the first flexible sensing layer is located on a side of the second flexible sensing layer away from the second substrate; the first substrate comprises at least one first circuit layer and at least one first conductive hole, wherein 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 comprises at least one second circuit layer and at least one second conductive hole, wherein 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.

[0005] The present application also proposes a method for manufacturing an embedded flexible sensor, comprising the following steps:

[0006] A first substrate and a second substrate are provided, wherein 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 exposed from a surface of the first substrate; 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 exposed from a surface of the second substrate;

[0007] 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 end exposed from 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 end exposed from the second substrate;

[0008] Providing an adhesive layer, wherein the adhesive layer is provided with at least one through hole, the adhesive layer is provided between the first substrate and the second substrate, and the first flexible sensing layer and the second flexible sensing layer are provided 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 are overlapped through the through hole to form a flexible sensing element, and the adhesive layer covers the flexible sensing element.

[0010] The embedded flexible sensor of the present invention realizes embedding of the flexible sensor while forming a circuit board by arranging a first circuit layer and a first conductive hole in the first substrate, arranging a second circuit layer and a second conductive hole in the second substrate, and arranging a flexible sensing element in the adhesive layer, thereby facilitating the thinning and miniaturization of electronic products. In addition, by arranging the flexible sensing element as a stacked first flexible sensing layer and a second flexible sensing layer, the embedded flexible sensor has high sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a cross-sectional schematic diagram of a copper clad laminate provided in one embodiment of the present application.

[0012] Figure 2 It is Figure 1 The cross-sectional diagram of the copper clad laminate after a blind hole is opened is shown.

[0013] Figure 3 It is Figure 2 The schematic cross-sectional view of the process after the conductive paste is printed in the blind hole to form the first conductive hole is shown.

[0014] Figure 4 It is Figure 3 The cross-sectional schematic diagram shown is after the first metal coating is provided on the surface of the first copper layer.

[0015] Figure 5 It is Figure 4 The cross-sectional schematic diagram shown is after the first blackening layer is formed on the surface of the first metal coating.

[0016] Figure 6 Yes Figure 5 The cross-sectional schematic diagram of an intermediate body obtained after the first copper layer, the first metal coating layer and the first blackening layer are patterned to form a first circuit layer.

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

[0018] Figure 8 It is Figure 7The cross-sectional schematic diagram of the first substrate obtained after a protective layer is provided on the surface of the intermediate shown.

[0019] Fig. 9 It is Figure 8 The cross-sectional schematic diagram shown is a first substrate surface after a first flexible sensing layer is disposed thereon.

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

[0021] Fig.11 Yes Figure 8 The schematic diagram of the process of laminating the first substrate, the adhesive layer and the second substrate is shown.

[0022] Fig.12 It is a schematic diagram of the process of simultaneously manufacturing a first substrate and a second substrate in one embodiment of the present application.

[0023] Fig.13 It is a cross-sectional schematic diagram of an embedded flexible sensor provided in one embodiment of the present application.

[0024] Fig.14 yes Fig.13 Schematic diagram of the enlarged structure of the flexible sensor shown.

[0025] 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] The first copper layer 102 The second glue layer 52

[0030] Blind hole 103 Second covering film 53

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

[0032] First metal coating 12 Second copper layer 541

[0033] First black layer 13 Second metal coating 542

[0034] First circuit 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 cover film 222 Second convex portion 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 specific implementation manner will further illustrate the technical solution of the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work 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 those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0048] See also Figures 1 to 14 A method for manufacturing an embedded flexible sensor 100 according to a preferred embodiment of the present invention comprises the following steps:

[0049] Step S1, see Figure 8 , providing a first substrate 25 , wherein the first substrate 25 includes a first circuit layer 15 and a first conductive via 11 , wherein the first conductive via 11 is electrically connected to the first circuit layer 15 .

[0050] In some embodiments, the first substrate 25 has a thickness direction N, and the first substrate 25 may include a first insulating layer 101, a first adhesive layer 221, and a first covering film 222 stacked in sequence along the thickness direction N. The first circuit layer 15 is disposed in the first adhesive layer 221, and the first conductive hole 11 is penetrated in 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 layer 12, and a first blackening layer 13 sequentially stacked along the thickness direction N. In other embodiments, the first circuit layer 15 may also include only the first copper layer 102 and the first blackening layer 13 without including the first metal coating layer 12.

[0052] See also Figures 1 to 8 The first substrate 25 can be manufactured by but not limited to the following manufacturing method, which specifically includes the following steps:

[0053] Step S11, see Figure 1 , a copper clad laminate 10 is provided, wherein the copper clad laminate 10 includes a first insulating layer 101 and a first copper layer 102 stacked along the thickness direction N.

[0054] Step S12, see 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 may be opened by, but is not limited to, laser drilling.

[0056] Step S13, see Figure 3 , a conductive paste is vacuum printed in the blind hole 103 to plug the hole to form the first conductive hole 11.

[0057] The conductive paste may be silver paste or copper paste.

[0058] Step S14, see Figure 4 A first metal coating 12 is disposed on a surface of the first copper layer 102 away from the first insulating layer 101 , and the first metal coating 12 includes a metal single substance powder.

[0059] Wherein, step S14 specifically includes:

[0060] A coating is provided, wherein the coating contains metal ions, a reducing agent and an adhesive, wherein the metal ions include at least one of silver ions, copper ions and iron ions, and the adhesive includes at least one of epoxy resins;

[0061] The coating is applied on the surface of the first copper layer 102 facing away from the first insulating layer 101 , and baked so that the metal ions react with the reducing agent, so that the metal ions are reduced into metal element powder.

[0062] Step S15, see Figure 5 , oxidizing the metal powder on the side of the first metal coating 12 facing away from the first copper layer 102 to form a first blackened layer 13 .

[0063] Specifically, an oxidant is sprayed on the surface of the first metal coating 12 away from the first copper layer 102, so that the metal element powder in part of the first metal coating 12 is oxidized into metal oxide, thereby forming the first blackened layer 13. The oxidant can be at least one of potassium sulfide solution, potassium thiosulfate, potassium polysulfide solution, and nitric acid solution.

[0064] It is understandable that, in other embodiments, the first blackened layer 13 may be formed by directly oxidizing a portion of the copper element of the first copper layer 102 away from the first insulating layer 101 .

[0065] Compared with the conventional method of directly oxidizing the first copper layer 102 to form a blackened layer, the method of providing the first metal coating 12 and oxidizing the first metal coating 12 to obtain the first blackened layer 13 is advantageous in avoiding the first copper layer 102 from becoming 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, and has a low surface roughness, thereby improving the conductivity of the subsequent first circuit layer 15 to a certain extent.

[0066] Step S16, see Figure 6 The first copper layer 102 and the corresponding first metal coating 12 and the first blackened layer 13 are synchronously patterned to form a first circuit layer 15 , and the first conductive via 11 is electrically connected to the first circuit layer 15 , thereby obtaining an intermediate 20 .

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

[0068] Step S17, see 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 provided. The protective layer 22 includes a stacked first adhesive layer 221 and a first covering film 222 . The first adhesive layer 221 faces the first insulating layer 101 , and the first adhesive layer 221 covers the first circuit layer 15 .

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

[0070] The first adhesive layer 221 is a transparent adhesive layer with a stretchable property. Specifically, the material of the first adhesive layer 221 includes one of polydimethylsiloxane (PDMS) and polyethylene terephthalate.

[0071] Step S2, see Fig. 9 A first flexible sensing layer 30 is disposed on a surface of the first insulating layer 101 away from the first adhesive layer 221 , and the first flexible sensing layer 30 is electrically connected to the first conductive via 11 .

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

[0073] The material of the first flexible sensing layer 30 mainly includes 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 be modified, 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, see Fig.10 , step S2 specifically includes:

[0075] Step S21 : coating a PEDOT:PSS solution on the glass substrate 110 by vacuum printing to form the first flexible sensing layer 30 .

[0076] The glass substrate 110 is provided with a plurality of cylindrical holes with a width of 25 μm to 50 μm and a depth of 10 μm to 30 μm, and the plurality of cylindrical holes are arranged in partitions.

[0077] Step S22: soaking the glass substrate 110 with the first flexible sensing layer 30 in sulfuric acid at room temperature for 10 minutes, and then drying 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 is changed, thereby reducing the hydrogen bonding adhesion between the first flexible sensing layer 30 and the glass substrate 110 to reduce transfer defects.

[0079] Step S23 , attaching the first flexible sensing layer 30 to the side of the first substrate 25 provided with the first insulating layer 101 , and transferring the first flexible sensing layer 30 from the glass substrate 110 to the first substrate 25 by utilizing the van der Waals force between the two.

[0080] Step S3, see Fig.11 , providing an adhesive layer 40 and a second substrate 50, wherein the adhesive layer 40 is disposed between the first substrate 25 and the second substrate 50, a second flexible sensing layer 60 is disposed on one side surface of the second substrate 50, and a through hole 42 is penetrated through the adhesive layer 40.

[0081] The second substrate 50 has a substantially similar structure to the first substrate 25. The second substrate 50 includes a second insulating layer 51, a second adhesive layer 52, and a second covering film 53 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 layer 542, and a second blackening layer 543 sequentially stacked along the thickness direction N.

[0082] It can be understood that the second substrate 50 can be manufactured by using substantially the same manufacturing method as the first substrate 25 , which will not be described in detail herein.

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

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

[0085] The adhesive layer 40 and the second adhesive layer 52 are transparent adhesive layers with stretchability. Specifically, the material of the adhesive layer 40 and the second adhesive layer 52 includes one of polydimethylsiloxane (PDMS) and 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, see Fig.12 A third substrate 120 can also be manufactured 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 correspondingly arranged 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 at the same time.

[0088] Step S4, see Fig.13 , along the thickness direction N, the first substrate 25, the adhesive layer 40 and the second substrate 50 are pressed together after the PIN is aligned, the first flexible sensing layer 30 and the second flexible sensing layer 60 are overlapped and accommodated in the through hole 42 to form a flexible sensing element 70, and the adhesive layer 40 covers the flexible sensing element 70 to obtain an embedded flexible sensor 100.

[0089] Since PSS is hydrophilic, the flexible sensor 70 with PEDOT:PSS as the main material is very susceptible to the influence of environmental humidity. The absorption of water molecules may cause the PSS shell to expand, resulting in a larger distance between adjacent PEDOT-rich cores, thereby increasing resistance and interfering with measurement accuracy. In the present application, by covering the first substrate 25 and the second substrate 50 on opposite sides of the flexible sensor 70, the flexible sensor 70 is embedded in the circuit board, which can suppress the problem of resistance value change caused by sulfonate groups in the PEDOT:PSS material absorbing environmental moisture, and effectively improve the measurement accuracy and reproducibility of the flexible sensor.

[0090] In some embodiments, please refer to Fig.13 and Fig.14 , the first convex portion 32 of the first flexible sensing layer 30 and the second convex portion 62 of the second flexible sensing layer 60 are staggered, that is, the first convex portion 32 is arranged corresponding to the second concave portion 63, and the second convex portion 62 is arranged corresponding to the first concave portion 33, so that the first flexible sensing layer 30 and the second flexible sensing layer 60 form a bionic interlocking structure. 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 has high sensitivity to lateral strain, and the sensitivity under low pressure (<10kPa) can reach 15.1kPa -1 .

[0091] In some embodiments, please refer to Fig.13 and Fig.14 In the first flexible sensing layer 30, the thickness of the first body 31 is 10μm-15μm, the length a is 300μm-500μm, the width b is 300μm-500μm, the height of the first protrusion 32 is 10μm-30μm, the width is 25μm-50μm, and the total thickness of the first flexible sensing layer 30 is 20μm-45μm. The size of the second flexible sensing layer 60 is consistent with the size of the first flexible sensing layer 30. The total thickness c of the flexible sensor 70 is 38μm-90μm, and the length of the force pressing area P corresponding to each of the flexible sensor 70 is 1000μm-1500μm, and the width is 1000μm-1500μm.

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

[0093] R=ρL / S=ρc / (ab)

[0094] Wherein, ρ is the material resistivity 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 the present application, the resistance of the embedded flexible sensor 100 can be adjusted by controlling the size of the flexible sensing element 70.

[0095] Since the first substrate 25 and the second substrate 50 are both made of transparent materials, the embedded flexible sensor 100 is transparent as a whole, and the transmittance can reach 90%. In addition, since PEDOT:PSS itself has strong mechanical properties and high ductility, the problem of glue overflow can be effectively solved when the upper and lower transparent circuit boards are pressed together with the adhesive layer 40. Furthermore, by providing the first blackening layer 13 and the second blackening layer 543, the overall visual transmittance can be improved, and the bonding strength between the first circuit layer 15 and the first covering film 222, and the second circuit layer 54 and the second covering film 53 can also be increased. The embedded flexible sensor 100 can be widely used in transparent wearable devices.

[0096] It is understandable that the embedded flexible sensor 100 in the present application is only exemplified by a two-layer circuit board. In other embodiments, it may also be a multi-layer circuit board.

[0097] See also Fig.13 and Fig.14 The present application also provides an embedded flexible sensor 100 manufactured by the above manufacturing method, wherein the embedded flexible sensor 100 comprises a first substrate 25, an adhesive layer 40, and a second substrate 50 stacked in sequence along a thickness direction N, wherein at least one flexible sensor 70 is disposed in the adhesive layer 40. The first substrate 25 comprises a first circuit layer 15 and a first conductive hole 11, wherein 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 sensor 70. The second substrate 50 comprises a second circuit layer 54 and a second conductive hole 55, wherein 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 sensor 70.

[0098] The flexible sensing member 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 a 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. A side of the first body 31 facing away from the first substrate 25 is alternately provided with a plurality of first convex portions 32 and first concave portions 33 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. A side of the second body 61 facing away from the second substrate 50 is alternately provided with a plurality of second convex portions 62 and second concave portions 63 in a direction perpendicular to the thickness direction N.

[0099] In some embodiments, the first convex portion 32 of the first flexible sensing layer 30 and the second convex portion 62 of the second flexible sensing layer 60 are staggered, the first convex portion 32 is arranged corresponding to the second concave portion 63, and the second convex portion 62 is arranged corresponding to the first concave portion 33, so that the first flexible sensing layer 30 and the second flexible sensing layer 60 overlap to form a bionic interlocking structure, so that the sensitivity of the embedded flexible sensor 100 under low pressure (<10kPa) can reach 15.1kPa -1 .

[0100] Among them, the material of the flexible sensor 70 mainly includes poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) composite material (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 structures of the first substrate 25 and the second substrate 50 are substantially the same. 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 covering film 222 sequentially stacked along the thickness direction N. The first circuit layer 15 is disposed in the first adhesive layer 221, and 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 black layer 13 sequentially stacked along the thickness direction N. In some embodiments, a first metal coating 12 may be further disposed between the first copper layer 102 and the first black layer 13 .

[0103] The second substrate 50 includes a stacked second insulating layer 51, a second adhesive layer 52 and a second covering film 53. A second circuit layer 54 is provided in the second adhesive layer 52. At least one second conductive hole 55 is penetrated in 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 black layer 543 stacked in sequence. In some embodiments, a second metal coating 542 may be disposed between the second copper layer 541 and the second black layer 543 .

[0105] 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 materials. 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 is only a preferred embodiment of the present invention and is not intended to limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. An embedded flexible sensor, characterized in that: The invention comprises at least one flexible sensing element and a first substrate, an adhesive layer and a second substrate stacked in sequence along a thickness direction, wherein the flexible sensing element is arranged in the adhesive layer and is covered by the first substrate, the adhesive layer and the second substrate, wherein the flexible sensing element comprises a first flexible sensing layer and a second flexible sensing layer stacked along the thickness direction, wherein the first flexible sensing layer is located on a side of the second flexible sensing layer away from the second substrate; the first substrate comprises at least one first circuit layer and at least one first conductive hole, wherein 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 comprises at least one second circuit layer and at least one second conductive hole, wherein 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 according to claim 1, characterized in that: The first flexible sensing layer includes first convex portions and first concave portions alternately arranged in a direction perpendicular to the thickness, and the second flexible sensing layer includes second convex portions and second concave portions alternately arranged in a direction perpendicular to the thickness, the first convex portions and the second concave portions are arranged correspondingly, and the first concave portions and the second convex portions are arranged correspondingly.

3. The embedded flexible sensor according to claim 1, characterized in that: The first substrate further includes a first insulating layer, a first adhesive layer and a first covering film sequentially stacked along the thickness direction, the first circuit layer is arranged 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 covering film sequentially stacked along the thickness direction, the second circuit layer is arranged 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.

4. The embedded flexible sensor according to claim 3, 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 materials.

5. The embedded flexible sensor according to claim 4, characterized in that: The material of the flexible sensor element includes poly(ethylene glycol)thiophene and polystyrene sulfonic acid, and the material of the first insulating layer, the first covering film, the second insulating layer and the second covering film are all polyethylene naphthalate.

6. The embedded flexible sensor according to claim 1, characterized in that: The first circuit layer includes a first copper layer stacked on a first black layer on a side of the first copper layer away from the flexible sensor, and the second circuit layer includes a second copper layer and a second black layer stacked on a side of the second copper layer away from the flexible sensor.

7. A method for manufacturing an embedded flexible sensor, characterized in that: The following steps are involved: A first substrate and a second substrate are provided, wherein 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 exposed from a surface of the first substrate; 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 exposed from 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 end exposed from 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 end exposed from the second substrate; Providing an adhesive layer, wherein the adhesive layer is provided with at least one through hole, the adhesive layer is provided between the first substrate and the second substrate, and the first flexible sensing layer and the second flexible sensing layer are provided 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 flexible sensing layer and the second flexible sensing layer are overlapped through the through hole to form a flexible sensing element, and the adhesive layer covers the flexible sensing element.

8. The method according to claim 7, characterized in that: The step of "disposing at least one first flexible sensing layer on one side of the first substrate" includes: Applying a mixed solution of polydioxyethylthiophene and polystyrene sulfonic acid on a glass substrate to form the first flexible sensing layer; soaking the glass substrate in sulfuric acid and then drying it; The first substrate is attached to the dried first flexible sensing layer, and the first flexible sensing layer is transferred to the first substrate by using van der Waals force.

9. The method according to claim 7, characterized in that: The first flexible sensing layer includes first convex portions and first concave portions alternately arranged in a direction perpendicular to the thickness, and the second flexible sensing layer includes second convex portions and second concave portions alternately arranged in a direction perpendicular to the thickness; The step of "pressing the first substrate, the adhesive layer and the second substrate together along the thickness direction" includes: The first convex portion corresponds to the second concave portion, and the first concave portion and the second convex portion overlap to form an interlocking structure.

10. The method according to claim 7, characterized in that: The method for manufacturing the first substrate comprises the following steps: Providing a copper-clad laminate, the copper-clad laminate comprising a first insulating layer and a first copper layer stacked along the thickness direction, and a first conductive hole penetrating the copper-clad laminate; Oxidizing a portion of the first copper layer away from the first insulating layer to form a first blackened layer; The first copper layer and the first blackened 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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