Method for producing combined touch and force sensor, in particular backlit sensor

Abstract

The invention relates to a sensor assembly comprising an electrically conductive nanoparticle assembly (560) in an insulating ligand on an active region (621, 622), a substrate on which electrically conductive paths (611, 612, 613, 650, 651) and the nanoparticle assembly are deposited, a thin reinforcement (630) extending below the active region, the thin reinforcement being bonded to the substrate by a hardening glue on a first side, and a pressure sensitive adhesive attached to a second side of the thin reinforcement opposite the first side for adhering the microsensor to the surface to be functionalized. The invention also relates to a method for producing such a sensor assembly.

Description

Technical Field

[0001] The present invention is in the field of sensors, and in particular those sensors adapted to detect a touch and to deliver information proportional to the force applied during that touch.

[0002] The above-mentioned sensor can be backlit and can be used to replace control buttons, more specifically, including but not limited to applications in consumer products in the fields of computer terminals, control buttons inside vehicles, home appliances, etc.

[0003] The above-mentioned sensor can integrate tactile control proportional to the applied force on any type of surface (whether rigid or flexible) by simple bonding, thereby advantageously replacing the control traditionally achieved with buttons or mechanical selectors. It has the advantages of low thickness, adjustable sensitivity, simpler integration, no moving parts, and no mechanical closing / opening of contacts. Background Art

[0004] A similar sensor can be realized by means of a nanoparticle assembly as described in document EP 2601491A1.

[0005] The sensor described in this document has a very high sensitivity and, through its operation, can be attached to the surface of any rigid or flexible substrate in order to functionalize this surface.

[0006] As a non-limiting example, such a sensor can be directly adhered to a touch exposed surface or back of an automotive accessory, such as an armrest, dashboard, or console. Pressure applied to the area where the sensor is located can control an action, such as the lowering or raising of a power window, the operation of a windshield wiper, etc., thereby avoiding the need to install any kind of mechanical switch.

[0007] Furthermore, the sensor exhibits a variable response depending on the amount of applied force, and its information can be used directly to control the target device, for example, higher pressure results in higher windshield wiper speed.

[0008] Document EP 4111151A1 provides an example of application of such a sensor in the automotive field.

[0009] According to a specific embodiment, a sensor suitable for this type of application is a combined touch and force type sensor as described in document WO2021170883, which includes a proximity sensor and a force sensor, the sensor including a conductive path to produce a capacitive sensor and a force sensor, the force sensor including a composition of conductive or semiconductor nanoparticles; in a colloidal suspension in an electrically insulating ligand, the nanoparticle assembly is deposited between electrodes, which is conducive to forming an interlacing as described in document WO2023111344, leaving an open or transparent central area, thereby enabling the backlit pictograms to appear.

[0010] These existing sensors have many advantages, but they are not suitable for mass production for at least two reasons:

[0011] attaching a sensor to the surface to be functionalized; and

[0012] The production of a sensor or a set of sensors according to the prior art is carried out by micro-printing.

[0013] In fact, the surface functionalization technology described in document EP287711B1, although effective for the applications mentioned in this document, is not very suitable for installing a large number of sensors dispersed on various flexible and rigid surfaces in crowded, inaccessible environments, such as in the interior of a car (whose components can be sourced from various manufacturers). In addition, the manufacturing method disclosed is not conventional and requires the development of expensive equipment for large-scale implementation.

[0014] It is possible to consider first depositing the sensor on a first substrate, such as a flexible substrate, and then placing the formed assembly on a rigid or flexible surface to be functionalized (including the assembly of the first substrate and the sensor also being bonded to the surface to be functionalized); for example, by using a hardening polymerizable liquid glue of the cyanoacrylate or epoxy resin type to provide firm support and good mechanical coupling between the assembly of the first substrate and the sensor and the aforementioned surface to be functionalized.

[0015] However, such liquid adhesives need to be applied precisely over a small surface area and are not suitable for large-scale manufacturing processes, so pressure-sensitive adhesive (PSA) films are preferred in the automotive industry.

[0016] However, using a pressure-sensitive adhesive film to achieve such bonding will, on the one hand, reduce the sensor's ability to detect applied force, thereby significantly reducing the sensitivity of the sensor; on the other hand, it will cause relaxation phenomena, affecting the response of the sensor. Summary of the invention

[0017] The above-mentioned problems of the prior art are overcome by a sensor assembly, which comprises:

[0018] A microsensor having an assembly of conductive nanoparticles in insulating ligands over an active area;

[0019] a substrate on which the conductive tracks and the nanoparticle assembly are deposited;

[0020] a thin reinforcement member bonded to the substrate on the first side of the thin reinforcement member by a hardened adhesive and extending below the active area; and

[0021] A pressure sensitive adhesive, attached to a second side of the thin reinforcement opposite the first side, is used to bond the microsensor to the surface to be functionalized.

[0022] Thus, the thin reinforcement allows the sensor assembly to be attached to the surface to be functionalized (whether flexible or rigid) by means of a pressure-sensitive adhesive, avoiding the disadvantages of the relaxation phenomenon.

[0023] The nanoparticle-based technology achieves low sensitivity to deformations in the active area, which can be kept sufficiently high despite the presence of thin reinforcements.

[0024] The sensor assembly of the present invention can be implemented according to the following embodiments and modifications, which can be applied alone or in any technical combination.

[0025] According to some exemplary embodiments, the thin reinforcement may be formed of polycarbonate having a thickness between 0.05 mm and 0.2 mm.

[0026] According to some exemplary embodiments, the substrate may be transparent, and the material of the substrate may be selected from polyethylene terephthalate, cycloolefin (co)polymer, and polyimide.

[0027] The conductive path may include a metal path selected from copper, gold, nickel, and cupronickel.

[0028] The conductive path may include a transparent conductive region made of a material selected from the group consisting of indium-doped tin oxide and a conductive transparent polymer.

[0029] According to some exemplary embodiments, the sensor assembly may further include a transparent central region, and the active region includes the nanoparticle assembly located at the edge of the central transparent region. This embodiment enables the backlit graphic text to be positioned in the central transparent region.

[0030] A method for manufacturing a combined proximity and force sensor assembly may include the following steps:

[0031] a laminate obtaining step of obtaining a laminate including a conductive metal layer disposed on a polymer substrate;

[0032] a path fabrication step, fabricating paths in the conductive metal layer by photolithography;

[0033] a deposition step of depositing at least one conductive nanoparticle assembly in the insulating ligands above and between the paths in the active area by micro-printing to obtain a force sensor;

[0034] a reinforcing step of bonding a thin reinforcing member extending below the active area to the polymer substrate with a hardening adhesive; and

[0035] The attaching step attaches the pressure sensitive adhesive film to the thin reinforcement member.

[0036] Compared to microprinting on substrates, this approach can use lamination and printed circuit board lithography to manufacture large quantities of modular sensor components and precisely manufacture conductive paths.

[0037] According to some embodiments, the conductive metal layer can be made of a metal selected from copper, gold, nickel and white copper alloy, the polymer substrate can be transparent, and the conductive metal layer is removed in the central transparent area by photolithography, so that the combined proximity and force sensor assembly has a transparent central area.

[0038] According to a first variation of this embodiment, the laminate comprises a transparent conductive film below the conductive metal layer, and the method further comprises the step of photolithography of the transparent conductive film in a central transparent region to obtain at least one transparent conductive region configured as a capacitive sensor.

[0039] According to another variation of this embodiment, the manufacturing method may further include: a micro-printing step of micro-printing at least one transparent conductive region in the transparent central region with a transparent conductive polymer to obtain a capacitive sensor.

[0040] Microprinting can be performed in the transparent central area by inkjet.

[0041] Alternatively, micro-printing can also be performed in the transparent central area by screen printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The sensor assembly of the present invention and the exemplary manufacturing method thereof can be described as follows, with reference to Figure 1-9 The non-limiting embodiment shown is implemented in which:

[0043] Figure 1 Related to the prior art, a microsensor mounted on a surface to be functionalized is shown in cross-section;

[0044] Figure 2 In the prior art, it is shown that in the case of bonding with hardening glue and bonding with pressure-sensitive adhesive film, Figure 1 Comparison of the time response of the microsensors under load steps;

[0045] Figure 3 The sensor assembly is shown in cross-section bonded to the surface to be functionalized via a pressure-sensitive adhesive film;

[0046] Figure 4 The following diagram shows the bonding conditions when using a hardening adhesive and a pressure-sensitive adhesive film. Figure 3 Comparison of the temporal response of the sensor assembly under load steps is shown;

[0047] Figure 5 Two examples of manufacturing an active area (force sensor) of a sensor assembly including a transparent central area are schematically shown in a top view and a partial enlarged view;

[0048] Figure 6 An example of a sensor assembly is schematically shown in top view, the sensor assembly including a force sensor and a proximity sensor located in a central transparent area thereof;

[0049] Figure 7 Two examples of laminates suitable for making conductive paths by photolithography are shown from a cross-sectional view;

[0050] Figure 8 according to Figure 6 A simplified view of a defined partial section AA shows an exemplary embodiment of a sensor assembly;

[0051] Fig. 9 is a flow chart of an exemplary embodiment of the method of the present invention. DETAILED DESCRIPTION

[0052] Figure 1 Referring to the prior art, it shows the bonding of a microsensor 110 on a surface to be functionalized 101. The microsensor 110 is bonded to the surface to be functionalized by means of a hardening polymerizable glue 120 of the cyanoacrylate or epoxy type applied in liquid state.

[0053] However, such liquid adhesives must be applied precisely on a small area during application, which is not suitable for mass production manufacturing processes such as the automotive industry, and the microsensor 110 needs to remain in contact with the surface to be functionalized 101 during the polymerization time of the adhesive. Even robots find it difficult to achieve such a process, so pressure-sensitive adhesives (PSAs) in the form of films are more suitable for this implementation.

[0054] However, if Figure 2 As shown, if a pressure-sensitive adhesive film is used instead Figure 1 The adhesive layer 120 will, on the one hand, reduce the sensor's ability to detect applied force, thereby significantly reducing the sensitivity of the sensor; on the other hand, it will cause relaxation, causing the sensor's response to change.

[0055] Figure 2 The time-output curve 202 shows an example of the time response 210 of a microsensor bonded with a hardened adhesive to a loading step. Figure 1 As shown in; Figure 2 Also shown is an example of the time response 220 of the same microsensor, but in which the hardened glue layer (ie Figure 1120) has been replaced by a pressure sensitive adhesive film. In both cases, the loading levels are similar.

[0056] A hardening glue is a glue that, once applied in liquid form, cures and hardens through a polymerization process, forming strong polymer chains that tightly bind the materials together.

[0057] A pressure-sensitive adhesive is an adhesive that adheres to a surface when pressure is applied. When pressure is applied, the adhesive flows, covering the surface area it contacts, creating sufficient adhesion. Pressure-sensitive adhesives do not cure or crosslink after application, but remain in a viscoelastic state.

[0058] The output curves 210, 220 are independent of the nature of the object carrying the surface 101 to be functionalized, whether it is flexible (such as fabric) or rigid (such as metal, wood), whether the microsensor 110 is directly exposed to the touch or mounted on the back of the touch surface.

[0059] like Figure 3 As shown, according to some exemplary embodiments, the sensor assembly 350 of the present invention includes a micro sensor 110, which is bonded to a thin reinforcement member 310 by a hardening glue (such as epoxy resin or cyanoacrylate type glue, not shown in the figure) during manufacturing. The thin reinforcement member 310 is made of, for example, polycarbonate with a thickness between 0.05 mm and 0.2 mm.

[0060] The sensor assembly 350 further comprises a pressure-sensitive adhesive film 330 attached to the underside of the thin reinforcement 310 , enabling the sensor assembly 350 to be adhered to the surface 101 to be functionalized.

[0061] Figure 4 Compared with Figure 1 The time response 210 of the microsensor 110 shown mounted on the surface to be functionalized 101 by means of hardened glue, and the time response 420 of the sensor assembly 350 adhered to the same surface to be functionalized 101 by means of a pressure sensitive adhesive film 330, the continuous loading process experienced in both cases being the same.

[0062] Thus, the thin reinforcement 310 greatly reduces relaxation phenomena in the temporal response 420 of the sensor assembly 350 adhered to the surface to be functionalized 101 via the pressure sensitive adhesive film 330 .

[0063] The output curve 420 is independent of the nature of the object bearing the surface 101 to be functionalized, whether it is flexible (such as fabric) or rigid (such as metal, wood), whether the microsensor 350 is directly exposed to the touch or mounted on the back of the touch surface.

[0064] like Figure 5As shown, according to some embodiments, microsensors 501 , 502 include a transparent central region 590 .

[0065] In particular, this arrangement allows the backlit graphic text to be displayed in the transparent central area 590 when the sensor assembly is adhered to a surface to be functionalized having such graphic text.

[0066] In the two exemplary embodiments described above, the microsensor 501, 502 at the top of the sensor assembly comprises a force sensor extending around and outside a transparent central area 590 and also comprises two conductive paths 511, 512 or 521, 522 at least partially interlaced and made of copper, for example.

[0067] According to some embodiments, the two conductive paths 511, 512 of the microsensor 501 located at the top of the sensor assembly are staggered around the transparent central area 590; according to another embodiment, the two conductive paths 521, 522 of the microsensor 502 located at the top of the sensor assembly are staggered in two areas on both sides of the transparent central area 590.

[0068] Therefore, the effective area constituting the force sensor is at least one area extending below the interleaved area of ​​the conductive paths 511 , 512 or 521 , 522 .

[0069] The above embodiments are only examples of transparent central region 590 being substantially rectangular. Those skilled in the art will appreciate that the region may be of any other shape, and the number of interlaced regions of electrodes surrounding the transparent central region may be any number depending on the intended application scenario.

[0070] To fabricate a force sensor, the conductive nanoparticle assembly in the insulating ligand 560 is deposited in the interdigitated region between the conductive pathways 521 , 522 , such that the nanoparticle assembly 560 extends between the two interdigitated pathways 521 , 522 and is in electrical contact with both.

[0071] As non-limiting examples, the nanoparticles of the component may be gold, copper, carbon or indium doped tin oxide (ITO) nanoparticles. The ligand is for example based on phosphonic acid.

[0072] The nanoparticle assembly 560 is deposited, for example, by a micro-printing technique such as inkjet or screen printing.

[0073] The micro sensors 501, 502 are located on top of the sensor assembly and are bonded to a thin reinforcement member extending below the effective area where the conductive paths intersect by hardening adhesive, and the pressure-sensitive adhesive film is adhered to the underside of the thin reinforcement member by hardening adhesive, and the sensor assembly is attached to the surface to be functionalized so that the sensor assembly is exposed to touch, or attached to the back of the touch surface.

[0074] According to some exemplary embodiments, the thin reinforcement may or may not cover the transparent central area, and when the thin reinforcement extends over the transparent central area, it is also made of a transparent material.

[0075] like Figure 6 As shown, according to some other exemplary embodiments, the microsensor 601 on the top of the sensor assembly includes a transparent central area 690 and at least two conductive paths 611, 612, the conductive paths 611, 612 include effective areas 621, 622, the two conductive paths 611, 612 in the effective areas 621, 622 are staggered with each other, and the nanoparticle assembly is deposited between the conductive paths to form a force sensor.

[0076] Furthermore, the microsensor may include at least one conductive path 650, 651 that extends into the transparent central region 690 and forms a capacitive sensor capable of detecting the proximity of an object hovering a short distance above the sensor.

[0077] By detecting this proximity, a potential touch can be detected before the object actually touches the functionalized surface, which is further confirmed by the touch sensor.

[0078] This early detection of a touch event, before the touch actually occurs, enables resetting the zero value of the force sensor (whose output values ​​may drift over time).

[0079] Thus, according to an exemplary embodiment, the transparent central area 690 includes a connection path located at the periphery of the transparent central area. The connection path is made of copper by photolithography, for example, and the conductive path 651 is made by micro-printing of transparent conductive ink (for example, PEDOT type), covering most of the transparent central area 690 and the connection path 650.

[0080] The advantages of this combination of proximity sensor and force sensor are particularly explained in document WO2021170883.

[0081] The conductive pathway 651 in the transparent central region 690 may be connected to the electrical connection terminal 640 of the sensor assembly through the connection pathway 650 and at least one other conductive pathway 613 .

[0082] To make the sensor assembly, a thin reinforcement is first bonded to the microsensor, e.g. Figure 6 The thin reinforcement member is provided below the shaded area 630 and a pressure sensitive adhesive film is adhered below the thin reinforcement member.

[0083] Figure 7One or more micro sensors are shown to be placed on top of a sensor assembly, each of which comprises a transparent central area including a transparent proximity sensor and a force sensor on the edge of the transparent central area, which can be economically and massively produced by techniques used to manufacture printed circuits, starting from a laminate 701, 702 comprising a conductive metal layer 711 located on a transparent polymer substrate 710.

[0084] As non-limiting examples, the polymer substrate 710 is composed of polyethylene terephthalate (PET), cyclic olefin (co)polymer (COP, COC), or polyimide with a thickness between 100 μm and 300 μm.

[0085] The conductive metal layer 711 is made of, for example, copper, gold, nickel or alloys thereof (such as white copper alloy) and has a thickness between 150 nm and 15 μm (1 nm = 10 -9 m, 1μm=10 -6 m).

[0086] According to some exemplary embodiments, the laminate 702 may include an intermediate transparent conductive layer 712 located between the transparent polymer substrate 710 and the conductive metal layer 711 and disposed below the conductive metal layer 711. The intermediate transparent conductive layer 712 is made of, for example, indium-doped tin oxide (ITO), and its thickness may also be between 150 nm and 15 μm.

[0087] Using such a laminate 701, 702, all conducting paths can be produced in an economical manner by photolithography, just as printed circuits are mass produced.

[0088] Back to Figure 6 According to an exemplary embodiment, all opaque conductive paths 611, 612, 613, 650 may be photolithographically formed. Figure 7 In the copper layer of the laminate shown, if the laminate includes a transparent conductive layer 712, the transparent conductive region 651 can be etched into the transparent conductive layer 712 ( Figure 7 ), and the conductive layer is removed by photolithography outside the conductive paths 611, 612 and 613, 650.

[0089] Multiple such microsensors 601 can be photolithographically fabricated simultaneously on a single laminate.

[0090] Precision lithography can achieve an accuracy of 10μm while still being suitable for volume production.

[0091] The laminates 701, 702 may include a coating of a conductive metal layer 711 and, according to this embodiment, a transparent conductive layer 712 is coated on both sides thereof, which makes it possible, for example, to manufacture a proximity sensor on one side and a force sensor on the other side, or to manufacture a force sensor on each side to achieve thermal compensation, as described in U.S. Patent No. 11366029B2.

[0092] By micro-printing using inkjet or screen printing in the active area, the nanoparticle assembly is deposited between and on the conductive paths.

[0093] Screen printing also enables each nanoparticle to be deposited at once on a photolithographic laminate containing multiple microsensors with a positional accuracy of approximately ±50 μm.

[0094] According to another exemplary embodiment, starting from a laminate 701 that does not comprise a transparent conductive layer 712 , the transparent conductive areas 651 are also produced by microprinting techniques, for example using a transparent conductive polymer of the PEDOT (poly(3,4-ethylenedioxythiophene)) type.

[0095] Microprinting can be done by inkjet or screen printing.

[0096] The surface of the laminate receiving microprinting may be previously treated with plasma in order to clean and activate it prior to microprinting.

[0097] One or more protective films, for example made of polyimide or PET, with a thickness between 25 μm and 50 μm, may be deposited on each microsensor made on the laminate by screen printing.

[0098] According to some exemplary embodiments, to manufacture the sensor assembly, a laminate including micro sensors is attached and bonded to a surface of a plate for manufacturing a thin reinforcement, and then a pressure-sensitive adhesive film including a peelable protective layer is attached under the thin reinforcement.

[0099] Individual microsensors can then be cut from the board.

[0100] Therefore, if Figure 8 As shown, each sensor component 801 is in the form of a sandwich, including a transparent polymer substrate 710, which is rigidly bonded to a thin reinforcement 830 at the active area position through one of its faces, and a pressure-sensitive adhesive film 840 is attached to the thin reinforcement 830, so that the sensor component can be bonded to the surface to be functionalized.

[0101] On the reverse side, the transparent polymer substrate 710 comprises conductive paths 611, 612, 650 obtained by photolithography. In the active area, nanoparticle assemblies 560 are deposited on and between these conductive paths by microprinting techniques.

[0102] A transparent conductive region 651 is formed in the transparent central region by photolithography or micro-printing technology.

[0103] The first protective layer 851 is deposited by, for example, screen printing, and the second protective layer 852 is deposited on the first protective layer 851 .

[0104] The total thickness 890 of the sensor assembly thus manufactured is between 0.15 mm and 0.3 mm.

[0105] like Fig. 9 As shown, the manufacturing method first starts with the laminate 910 to be obtained.

[0106] The laminate comprises a transparent polymer substrate and a conductive metal layer on top of the substrate, and may or may not comprise an intermediate transparent conductive layer.

[0107] In the path making step 920, conductive paths are engraved in the top conductive layer of the laminate by photolithography to form an active area, while forming a transparent center area where the top conductive layer is completely removed.

[0108] If the laminate comprises an intermediate transparent conductive layer a, in a first alternative step 925 the capacitive sensor is produced in the transparent central area by photolithography in the transparent conductive layer 925 of the laminate.

[0109] If the laminate does not include an intermediate transparent conductive layer, a capacitive sensor may be deposited in a second optional step 930 in the transparent central area by micro-printing a transparent conductive polymer such as PEDOT.

[0110] In a nanoparticle deposition step 940, conductive nanoparticle assemblies in an insulating ligand are deposited between and on the conductive pathways of the active area.

[0111] In a protection step 950, one or more protection layers are deposited on top of the component by micro-printing.

[0112] In the reinforcing step 960, a thin reinforcement is bonded to the lower surface of the substrate by hardening glue.

[0113] Finally, the method further comprises the step of attaching 970 a pressure sensitive film beneath the thin reinforcement member.

Claims

1. A sensor assembly (350), characterized in that: include: A microsensor (110, 501, 502, 601) having a conductive nanoparticle assembly (560) in an insulating ligand on an active area (621, 622); a substrate on which conductive tracks (511, 512, 521, 522, 611, 612, 613, 650, 651) and nanoparticle assemblies are deposited; a thin reinforcement member (330, 630, 830) bonded to the substrate on the first surface of the thin reinforcement member by hardening adhesive and extending below the active area; as well as A pressure sensitive adhesive (840) is attached to a second side of the thin reinforcement (330, 630, 830) opposite to the first side, for bonding the microsensor to the surface to be functionalized.

2. The sensor assembly according to claim 1, characterized in that: in, The thin reinforcement (330, 630, 830) is made of polycarbonate with a thickness between 0.05 mm and 0.2 mm.

3. The sensor assembly according to claim 1, characterized in that: in, The substrate is a transparent substrate (710), and the material of the substrate is selected from polyethylene terephthalate, cycloolefin (co)polymer and polyimide.

4. The sensor assembly according to claim 1, characterized in that: in, The conductive paths (511, 512, 521, 522, 611, 612, 613, 650) include metal paths selected from copper, gold, nickel and white copper alloy.

5. The sensor assembly according to claim 1, characterized in that: in, The conductive path includes a transparent conductive region (651) made of a material selected from the group consisting of indium-doped tin oxide and conductive transparent polymers.

6. The sensor assembly according to claim 1, characterized in that Also includes: A transparent central region (590, 690), the active region comprising nanoparticle assemblies located at the edge of the central transparent region.

7. A method for manufacturing a combined proximity and force sensor assembly (801), characterized in that: The following steps are involved: a laminate obtaining step (910) of obtaining a laminate including a conductive metal layer (711) disposed on a polymer substrate; a path making step (920) of making a path in the conductive metal layer by photolithography; a deposition step (940) of depositing, in the active area (621, 622), at least one conductive nanoparticle (560) component in the insulating ligands above and between the paths by micro-printing to obtain a force sensor; a reinforcing step (960) of bonding a thin reinforcing member (330, 630, 830) extending below the active area (621, 622) to the polymer substrate (710) using a hardening adhesive; as well as The attaching step (970) attaches a pressure sensitive adhesive (840) film to the thin reinforcement (330, 630, 830).

8. The manufacturing method according to claim 7, characterized in that: in, The laminate (621, 622) includes a conductive metal layer, the conductive metal layer is made of a metal selected from copper, gold, nickel and white copper alloy, the polymer substrate (710) is a transparent substrate, and the conductive metal layer (711) is removed in the central transparent area (690) by photolithography, so that the combined proximity and force sensor assembly has a transparent central area (690).

9. The manufacturing method according to claim 8, characterized in that: in, The laminate (702) includes a transparent conductive film (712) located below the conductive metal layer, and the method also includes a step (925) of photolithography of the transparent conductive film in the central transparent area (690) to obtain at least one transparent conductive area (651) configured as a capacitive sensor.

10. The manufacturing method according to claim 8, characterized in that: Also includes: A micro-printing step (930) is performed to micro-print at least one transparent conductive region (651) in the transparent central region (690) with a transparent conductive polymer to obtain a capacitive sensor.

11. The manufacturing method according to claim 10, characterized in that: in, The micro-printing is performed in the transparent central area (690) by inkjet.

12. The manufacturing method according to claim 10, characterized in that: in, The micro-printing is performed in the transparent central area (690) by screen printing.

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