Methods of forming graphene devices

Abstract

The present invention relates to a method of forming a graphene device, the method comprising: forming a graphene film (100) on a substrate; depositing a polymer material covering the surface of the graphene film (100) by vapor deposition; and removing the substrate from the graphene film (100), wherein the polymer material forms a support (102) for the graphene film (100).

Description

[0001] This application is a divisional of the patent application for invention with international application date of March 9, 2016, Chinese national application number of 201680026619.7, and invention name of "Method of forming a graphene device". TECHNICAL FIELD

[0002] The present disclosure relates to the field of devices formed partially from graphene and methods of forming graphene devices. BACKGROUND

[0003] Graphene is a substance composed of carbon atoms forming a lattice one atom thick. Various applications of graphene have been proposed, including its use in radio frequency transistors and for forming transparent, highly conductive and flexible electrodes, for example for displays. It is particularly beneficial in applications requiring high mobility conductors. Most applications of graphene require graphene layers of macroscopic size, containing one or a few layers of carbon atoms, which are transferred onto a substrate of a material selected based on the particular application.

[0004] Graphene is typically formed using a chemical vapor deposition (CVD) process, in which graphene is deposited on a base substrate such as a copper foil. However, it is difficult to remove the graphene layer from the base substrate without damaging or contaminating the graphene layer and / or reducing its conductivity.

[0005] Furthermore, in some embodiments, it is desirable to provide a method of forming a three-dimensional (3D) graphene device.

[0006] Accordingly, there is a need in the art for an improved method of forming a graphene device and one or more graphene devices formed based on such a method. SUMMARY

[0007] It is an object of embodiments of the present disclosure to at least partially address one or more needs in the art.

[0008] According to one aspect, there is provided a method of forming a graphene device, the method comprising: forming a graphene film on a substrate; depositing a polymeric material covering a surface of the graphene film by vapor deposition; and removing the substrate from the graphene film, wherein the polymeric material forms a carrier for the graphene film.

[0009] According to one embodiment, the polymeric material comprises a polymer from the n-xylylene family.

[0010] According to one embodiment, the polymeric material comprises a parylene.

[0011] According to one embodiment, the polymeric layer is deposited at a thickness of 10 nm to 5 mm.

[0012] According to an embodiment, the graphene film is formed on a three-dimensional surface of the substrate.

[0013] According to an embodiment, removing the substrate from the graphene film is performed by a method of electrochemical delamination or using acid etching.

[0014] According to an embodiment, the method is for forming a sensor device to be placed on a three-dimensional shape, wherein: the substrate on which the graphene film is formed comprises a mold having a three-dimensional shape.

[0015] According to an embodiment, the mold is formed of a first material and at least one second material region; during formation of the graphene film, graphene is selectively formed on the at least one second material region and not on the first material; and the polymeric material is deposited on the graphene film and at least part of the first material.

[0016] According to an embodiment, the method further comprises, after removing the substrate from the graphene film, performing further vapor deposition of the polymeric material to encapsulate the graphene film.

[0017] According to an embodiment, the graphene film is deposited to form a conductive track having a meandering form in a detection region.

[0018] According to an embodiment, the graphene film is deposited in the form of a first graphene plate formed in a detection region and connected to a first conductive track, and the method further comprises: forming a further graphene film covered by further deposition of the polymeric material, wherein the further graphene film is deposited in the form of a second graphene plate; and assembling the first graphene film and the second graphene film such that the first graphene plate and the second graphene plate form a capacitive interface separated by a layer of the polymeric material in the detection region.

[0019] According to another aspect, there is provided a sensor device comprising: a graphene film covered on at least one side by a polymeric material having a detection element formed by the graphene film on a portion of an inner surface thereof, the polymeric material contacting and supporting the graphene film.

[0020] According to an embodiment, the detection element comprises a meandering conductive track formed in a detection region and electrically connecting a first conductive track to a second conductive track.

[0021] According to an embodiment, the detection element comprises a first graphene plate and a second graphene plate at least partially overlapping each other, the first graphene plate connected to a first conductive track and the second graphene plate connected to a second conductive track.

[0022] According to one embodiment, the graphene device further comprises a detection circuit coupled to the first conductive track and the second conductive track. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The foregoing and other features and advantages will become apparent from the following detailed description of embodiments given by way of illustration and not limitation with reference to the accompanying drawings in which:

[0024] Figure 1 is a cross-sectional view of a graphene device according to an example embodiment of the present disclosure;

[0025] Figure 2 schematically illustrates an apparatus for forming a graphene device according to an example embodiment of the present disclosure;

[0026] Figure 3 A to 3C are cross-sectional views of a graphene forming apparatus according to one embodiment of the present disclosure;

[0027] Figure 4 A to 4C are cross-sectional views of forming a 3D graphene device according to one embodiment of the present disclosure;

[0028] Figure 5 Figure A shows a sensing device including graphene according to an example embodiment of the present disclosure;

[0029] Figure 5 B and 5D are diagrams showing the formation of Figure 5 A cross-sectional view of a step in the method of the sensing device of FIG.

[0030] Figure 6 According to an exemplary embodiment, the Figure 5 A sensing element of the sensing device;

[0031] Figure 7 shows a virtual keyboard arrangement according to an exemplary embodiment;

[0032] Figure 8 A shows in more detail according to an alternative embodiment Figure 5 A plan view of a sensing element of the sensing device of A; and

[0033] Figure 8 B is an exemplary embodiment according to the present disclosure including Figure 8 A sensor element Figure 5 A cross-sectional view of the sensing device.

[0034] For ease of illustration, the figures are not drawn to scale. DETAILED DESCRIPTION

[0035] In this specification, the term "connected" is used to indicate a direct electrical connection between two elements, while the term "coupled" is used to indicate an electrical connection between two elements, which may be direct or may be via one or more other components, such as resistors, capacitors, or transistors. Additionally, as used herein, the term "substantially" is used to indicate a range of + / - 10% of the value in question.

[0036] Figure 1 is a cross-sectional view of a graphene device comprising a graphene film 100 that is, for example, only one atom thick, or in some embodiments can have a thickness of up to 8 atomic layers, depending on the application and the desired conductivity. In particular, the graphene film 100 is formed, for example, by a plurality of graphene monolayers connected together. In certain embodiments, the graphene film 100 is doped, for example, with a P dopant (such as AuCl3 and / or HNO3) to reduce its surface resistance. Additionally or alternatively, a layer of one or more dopants, such as FeCl3, can be inserted between one or more of the graphene layers to reduce the resistance of the element. For example, such techniques are described in more detail in a publication entitled “Novel Highly Conductive and Transparent Graphene-Based Conductors” by I. Khrapach et al. in Advanced Materials 2012, 24, 2844-2849, the contents of which are incorporated herein by reference.

[0037] In the plan ( Figure 1 In the embodiment shown in FIG, the graphene film 100 may have any shape according to the application and may have a thickness between 1 μm and 2 μm, for example. 2 and 10cm 2 The surface area of ​​any value between .

[0038] The graphene film 100 is covered by a carrier 102 in the form of a layer of a polymer material. The polymer material is, for example, selected from the orthoxylene family and, in one embodiment, includes parylene. Parylene has the advantage of being able to stretch up to 200% before breaking and can remain flexible over a wide temperature range. In one example, the polymer material includes parylene C or parylene N. Parylene C and parylene N have the advantage of being relatively elastic, while parylene N has a slightly lower Young's modulus than parylene C and, therefore, has higher elasticity.

[0039] As will be described in more detail below, the polymeric carrier 102 is formed, for example, by a vapour deposition technique or by a spin-on deposition technique. The polymeric carrier 102 has, for example, a thickness of 10 nm to several tens or hundreds of pm, or up to 5 mm, depending on the application. In some embodiments, the thickness of the polymeric carrier 102 can be as low as 5 nm, for example in the range of 5 to 40 nm.

[0040] Although in the examples described below the polymeric carrier is in the form of a layer having a substantially uniform thickness, as will become apparent from the embodiments described below, the polymeric carrier can take other forms depending on the particular application. Figure 1

[0041] The combination of the graphene film 100 and the polymeric carrier 102 provides a multilayer which can have a relatively high electrical conductivity while retaining flexibility and strength. Of course, although in the multilayer described below there are only two layers - the graphene layer and the parylene layer forming a bilayer, in alternative embodiments there can be one or more further layers. For example, the graphene layer can be sandwiched between parylene layers on each side, and / or one or more further layers of material can be formed in contact with the graphene or parylene layers. Figure 1

[0042] Furthermore, the use of a polymer such as parylene results in a biocompatible device, making the device suitable for various applications in which it can, for example, come into contact with human or animal tissue.

[0043] Figure 2 An apparatus 200 for forming a graphene device such as the device 100 described above is shown according to one example embodiment. Figure 1

[0044] The step of forming the graphene film 100 involves, for example, the use of the apparatus 200 to form a single layer of graphene. A similar apparatus is described in the publication by Z. Han et al. entitled "Homogeneous Optical and Electronic Properties of Graphene Due to the Suppression of Multilayer Patches During CVD on Copper Foils", Adv. Funct. Mater., 2013, DOI: 10.1002 / adfm.201301732, the contents of which are incorporated herein by reference.

[0045] The apparatus 200 comprises a reaction chamber 202 in which the graphene film is formed. For example, the reaction chamber 202 is a tube furnace or other type of chamber which can be heated.

[0046] ​​​A substrate 204, for example formed of a copper foil having a thickness of 0.1 to 100 μιη, is placed inside the chamber 202. The substrate 204 provides a surface suitable for graphene formation. In particular, the material of the substrate 204 is for example selected as a material providing a catalyst for graphene formation, and for example has a relatively low carbon solubility. Other possible materials for forming the substrate 204 include for example other metals such as nickel, cobalt, or ruthenium or copper alloys, for example copper / nickel alloys, copper / cobalt alloys, copper / ruthenium alloys, or dielectric materials, for example zirconium dioxide, hafnium oxide, boron nitride and aluminum oxide. In some embodiments, the substrate 204 can have a 3D form instead of a foil.

[0047] The dimensions of such a substrate 204 can be anywhere from 0.1 μιη to several cm or more. Moreover, the substrate 204 can be formed on a planar or 3D surface of another substrate, for example of copper or another material such as sapphire.

[0048] An inlet 206 of the reaction chamber 202 allows for introducing a gas into the chamber, and an outlet 208 allows for withdrawing a gas from the chamber. The inlet 206 is for example supplied with gas by three gas reservoirs 210A, 210B and 210C, which store hydrogen gas (H2), argon gas (Ar) and methane (CH4), respectively, in the example. In alternative embodiments discussed in more detail below, different gases can be used. In particular, as an alternative to hydrogen gas, a different etching gas, in other words a gas that can react with carbon, such as oxygen, can be used. As an alternative to argon gas, another inert gas, such as helium, can be used. This gas is for example used to control the total pressure in the reaction chamber 202, and can in certain embodiments be omitted entirely. As an alternative to methane, a different organic compound, such as butane, ethylene or acetylene, can be used. Figure 2

[0049] The inlet 206 is coupled to the reservoir 210A via a tube 212A comprising a valve 214A; to the reservoir 210B via a tube 212B comprising a valve 214B; and to the reservoir 210C via a tube 212C comprising a valve 214C. The valves 214A to 214C control the flow rate of the respective gas into the chamber.

[0050] The valves 214A to 214C are for example electronically controlled by a computing device 216. The computing device 216 for example comprises a processing device 218 storing program code for controlling at least part of the graphene formation process under control of an instruction memory 220.

[0051] ​An outlet 208 is coupled to a vacuum pump 224, e.g., via a tube 222, to evacuate gas from the reaction chamber 202. The evacuation rate of the pump 224 is also controlled by the computing device 216, for example. The computing device can also control one or more heating elements of the reaction chamber 202 to heat the interior of the chamber during the graphene formation process, as represented by arrow 226.

[0052] A method of forming a graphene film using the above-described apparatus is discussed in more detail, for example, in U.S. Patent Application published as US 2014 / 0326700, the contents of which are incorporated herein by reference.

[0053] Further, a deposition chamber 228 is provided, for example, to deposit a polymer layer on the graphene film. In Figure 2 In embodiments, a flap door 230 in one wall of the chamber 202 and a passage 231 between the chambers 202, 228 allows the substrate 204 with the graphene film to be transferred between the chambers 202 and 228 without being exposed to the atmosphere. In alternative embodiments, the deposition chambers 202 and 228 can be separate from each other, and the substrate 204 with the graphene film can be transferred without using a passage.

[0054] The deposition chamber 228 includes, for example, an inlet 232 coupled to a supply chamber 234 via another valve 214D for providing a precursor for depositing a polymer material to cover the graphene film. The valve is controlled by the computing device 216, for example. As mentioned above, the polymer material is deposited, for example, using a vapor deposition method. The term "vapor deposition" is considered herein to include physical vapor deposition (PVD), chemical vapor deposition (CVD), and atomic layer deposition (ALD). The precursor is heated, for example, to between 100°C and 500°C in the supply chamber 234 before being introduced as a vapor into the chamber 228 through the valve 214D.

[0055] Figure 3 A to C are cross-sectional views of a graphene apparatus during its manufacture, for example, using Figure 2 the apparatus of Fig. 1.

[0056] As shown in Fig. A, it is initially assumed that a graphene film 100 has been formed on a substrate 204, for example, a copper foil, by CVD. Figure 3

[0057] Figure 3 B shows the operation of depositing a polymer carrier that covers the graphene film 100. In Figure 3 ​In embodiments of B, graphene is deposited on a relatively flat substrate 204 and a polymer material is deposited as a conformal layer 302 of substantially uniform thickness encapsulating the device including the substrate 204. For example, the device is suspended so that polymer is deposited on all faces of the device. Alternatively, the device can be flipped over during the deposition process. In further alternative embodiments, the polymer material can be deposited only on the graphene film 100. Furthermore, as will be described in more detail below, the polymer material is not deposited in the form of a layer, but in other forms.

[0058] Figure 3 C shows a subsequent operation in which the substrate 204 is removed, for example by an etching step or by delaminating the polymer layer having the graphene film 100 from the substrate 204. For example, the etching step comprises removing the polymer coating covering the substrate 204, for example using plasma etching or by scraping with a sharp blade, to expose the surface of the substrate. The substrate is then removed, for example using a suitable etch, for example an acid etch, or using an electrolytic technique. For example, an electrochemical delamination process can be carried out as described in detail in the publication by Yu Wang et al, entitled "Electrochemical delamination of CVD-Grown Graphene Film: Toward the recyclable use of copper catalyst", the contents of which are incorporated herein by reference to the extent legally permitted.

[0059] This leaves the graphene film 100 with a polymer carrier 102. The inventors have found that this polymer carrier 102 not only repairs any defects in the graphene film 100 to some extent, but also limits further degradation of the graphene film 100 during separation of the graphene film 100 from the substrate 204.

[0060] An advantage of the method described herein is that no transfer operation is required, reducing the risk that the properties of the graphene film will be degraded.

[0061] In fact, graphene is typically formed using a chemical vapour deposition (CVD) process in which graphene is formed on a base substrate such as a copper foil. However, it is difficult to remove the graphene layer from the base substrate without damaging or contaminating the graphene layer and / or degrading its conductivity.

[0062] By depositing the polymer material in contact with the graphene film by vapour deposition, the polymer can remain attached to the graphene while the substrate is removed, for example by etching or by a delamination process, without a transfer step.

[0063] For example, the graphene film 100 is formed on a substrate 204, for example a copper foil, as described above. The graphene film 100 is then removed from the substrate 204, for example by etching or by delamination, as described above. The graphene film 100 is then deposited on a substrate 204, for example a flexible substrate, as described above. Figure 3The method of graphene devices described in A to 3C can be adapted to form several specific graphene devices, such as now with reference to Figures 4 to 8 described.

[0064] Figure 4 A to 4C are cross-sectional diagrams showing steps in a method of forming a graphene device comprising a three-dimensional graphene film according to exemplary embodiments. Such a device is suitable for placement on or over a 3D form or device or part of a device, such as a human or animal member, and for example provides a sensor, protective barrier functionality, etc.

[0065] Figure 4 A shows an example of a cross-section of a mold 402 over which a graphene device is to be formed. Figure 4 The 3D form of this mold 402 shown in A is merely one example for illustration, and many different forms will be possible depending on the specific application. The mold is formed of a material that supports graphene growth, such as copper.

[0066] Figure 4 B shows operations in which a graphene film 100 is formed over the mold 402 and then a polymer (e.g., parylene) coating is deposited over the graphene film 100.

[0067] Figure 4 C shows subsequent operations to remove the mold, for example by an etching step or by delaminating the polymer layer with the graphene film 100 from the substrate 204, for example using a delamination operation as described above.

[0068] Figure 5 A shows a sensor device 500, which in this example is designed to be worn by a user over their index finger or other body part. Of course, the technology represented in relation to A can be applied to various different types of sensor, with one or more sleeves or tubes adapted to suitably surround a human or animal body part. For example, the sensor can be in the form of a glove with a sensor in each finger of the glove, in order to detect finger movement. Figure 5

[0069] Figure 5 The sensor device 500 of A includes a polymer (e.g., parylene) layer in the form of a sleeve or tube 502 that is sized to fit closely over a user’s index finger. In Figure 5 In the example of A, the sleeve 502 is closed at one end to form a finger. A graphene thin film is formed on a portion of the inner surface of the sleeve 502, and electrodes 504 and conductive tracks 506 are provided. The electrodes 504 are positioned to contact a portion of the underside of the finger near the tip of the finger. The electrodes 504 are coupled to an end 508 of the sleeve 502 opposite the tip of the finger via the conductive tracks 506. Although in the example of A the graphene film is formed on the inside of the sleeve 502, it is also possible to form the graphene film on the outside of the sleeve 502, or to form the graphene film on both the inside and outside of the sleeve 502. Figure 5 ​Not shown in A, but the end of the conductive track can be coupled to the monitoring device via a wire, or the monitoring device can be implemented by an integrated circuit mounted on one side of the sleeve 502.

[0070] Figure 5 B to 5D are during the process steps of forming Figure 5 A of the sensor device Figure 5 A of the sensor device 500. Figure 5 B to 5D correspond, for example, to Figure 5 A shown in line A-A, which passes through the part of the sleeve 502 close to the fingertip and through the electrode 504.

[0071] As Figure 5 B shows, a finger-shaped mold 510 is formed, for example, from a material that does not support graphene growth, such as aluminum oxide, which is the same size or approximately the same size as the index finger used in the sensor device 500. In the area in which the electrode 504 and the conductive track 506 are to be formed, a thin plating layer 512 of a material such as copper is formed, which supports graphene growth.

[0072] For example, to form the plating material 508 of copper or other material, one of two methods can be used.

[0073] The first method is described in more detail, for example, in the publication by J. Zhang et al. entitled "Electron Beam Lithography on Irregular Surfaces Using an Evaporated Resist", ACS Nano 2014, 8(4), pp. 3483-3489, the content of which is incorporated by reference to the extent legally permissible. According to such a lithography method, an electron- or photon-sensitive resist is evaporated depending on the type of lithography used and the resolution desired. Such a resist can be applied to the non-planar surface in the desired pattern, followed by a lithography operation.

[0074] The second method is described in more detail, for example, in the publication by J. Chang et al. entitled "Facile electron-beam lithography technique for irregular and fragile substrates", Applied Physics Letters 105, 173109 (2014), the content of which is incorporated by reference to the extent legally permissible. According to this technique, a resist film is prepared beforehand by spin coating and annealing. After this annealing, the resist film becomes firm and flexible and can be transferred to a non-planar surface and follow its 3D form. A lithography step can then be performed.

[0075] like Figure 2 C, and then place the mold in a Figure 5 The CVD chamber of the chamber 202 of the device is placed in the CVD chamber, and the graphene film 100 is selectively formed on the coating layer 512. The polymer layer is then applied to the mold (including the graphene film 100) to form a polymer layer in the form of a sleeve 502. The polymer coating has a thickness of, for example, 50 to 500 μm. When the polymer coating is in contact with the graphene film 100, it provides a polymer support for the graphene film 100.

[0076] like Figure 5 As shown in FIG. 4D , the polymer sleeve 502 and the graphene film 100 are removed from the mold, for example, by a delamination process or an electrochemical delamination process as described above.

[0077] Although Figure 6 In the example of A, the sensing device 500 comprises a single graphene conductive track 506 leading to a graphene sheet forming an electrode 504, but many other arrangements will be possible, as will now be described with reference to FIG. Figure 6 Just as described.

[0078] Figure 5 Shown according to an example Figure 5 A sensing device 500 is in the form of a graphene film 100, wherein two conductive tracks 602, 604 leading to electrodes are provided, and the electrodes are implemented in the form of meandering tracks, which electrically connect the track 602 to the track 604 and form a detection area 606. The tracks 602, 604 and the meandering tracks are for example used as described above with reference to Figure 6 B is formed by the photolithography or spin coating process described in FIG.

[0079] Conductive tracks 602, 604 are coupled to, for example, a detection circuit 608 for detecting a change in the resistance of the conductive tracks formed in the detection region. For example, circuit 608 is adapted to apply a substantially constant current through conductive tracks 602, 604 and monitor a voltage drop between conductive tracks 602, 604. Pressure applied to the graphene film in region 606 causes a change in the resistance of the graphene film, for example by deforming the graphene film and / or causing a short circuit between portions of the meandering conductive track. This change in resistance results in a corresponding change in the voltage across the conductive track, which is detected by detection circuit 608.

[0080] In one embodiment, Figure 7 The sensing device is used in a key stroke detection system, as will now be referred to Figure 7 Described in more detail.

[0081] Figure 7A virtual keyboard system is shown in which a projector 702 is provided, in this example mounted on top of a display 704. The projector 702 projects an image 706 of a user interface onto a surface. In Figure 5 the example, the user interface is a keyboard, but in alternative embodiments other types of user interface can be projected. For example, a screen image can be projected to provide the functionality of a touch screen. In this case, the display 704 can be omitted.

[0082] The system also includes, for example, a 3D ranging camera for detecting typing events made by a user on the projected image of the keyboard. Such virtual keyboard systems are discussed, for example, in the publication by Huan Du et al. entitled "A Virtual Keyboard Based on True-3D Optical Ranging", Proceedings of the British Machine Vision Conference, Volume 1, pages 220-229, the contents of which are incorporated herein by reference to the extent legally permitted.

[0083] A difficulty with such virtual keyboard systems is to confirm that a typing event has been visually detected. For example, a user can move a finger towards a key position with the intention of making a typing strike, but then pull back before touching the key position. Such an incomplete keystroke can be interpreted as an actual keystroke based on visual data alone.

[0084] To address this problem, the user has, for example, one or more sensing devices similar to those in Figure 6 and Figure 6 attached to one or more fingers. For example, the user wears gloves 708, 710 on his right and left hands respectively, which include such sensing devices in one, several or all of the fingers.

[0085] Although the meandering graphene tracks of Figure 8 provide one possible approach to detecting pressure applied in the detection region 606, other techniques can be employed, as will now be described with reference to Figure 8 A and 8B.

[0086] Figure 8 A is a plan view of a sensing device comprising a pair of graphene films, which include conductive tracks 802 and 804 respectively. One end of the conductive track 802 is connected to a graphene plate 806, while one end of the conductive track 804 is connected to a graphene plate 808. The graphene plates 806, 808 are arranged so that they overlap, and they are separated by a deformable insulating layer 810. Figure 8A) are separated so that they have an associated capacitance. An external compressive force applied to the plates 806, 808, for example caused by a finger striking the surface, will therefore change the distance between the plates and cause their capacitance to change, which can be detected by a detection circuit 809 coupled to the conductive tracks 802, 804.

[0087] Figure 5 B is similar to Figure 8 A cross-sectional view of a sensing device 800 of the device 500, but adapted to include Figure 8 A's sensing device.

[0088] The device 800 includes, for example, an outer polymer sleeve 810 having formed therein plates 808 and conductive tracks 804 extending along the length of the sleeve ( Figure 5 B). Such a structure is for example referred to Figure 8 B to 5D. The device 800 also has an inner polymer sleeve 812 having a graphene plate 806 formed on its outer surface (located near the graphene plate 808) and a conductive track 802 ( Figure 5 B). This structure can also be achieved by Figure 8 B to 5D, and then by turning the fingers inward so that the graphene sheet 806 is located outside the inner polymer sleeve 812. The polymer sleeve 812 is then positioned as an inner lining of the polymer sleeve 810 to achieve ​ Structure of B. The graphene sheets 806 , 808 are separated by an insulating layer 814 formed of, for example, a polymer, and may include a polymer coating formed on the graphene sheet 806 and / or a polymer coating formed on the graphene sheet 808 .

[0089] In use, the sensing device 800 is placed on a finger or other body part. A charge is then stored on one of the plates 806, 808, for example, by applying a voltage between the conductive tracks 802, 804, for example, via a detection circuit 809. The graphene plates 806, 808 then form a detection region, such that if pressure is applied in this region, the capacitance of the plates 806, 808 will change, resulting in a change in the voltage across the conductive tracks 802, 804. This voltage change can be detected by the detection circuit 809.

[0090] An advantage of the graphene devices described herein is that the polymer layer supports the graphene film 100 , helping to maintain the relatively high electrical conductivity of the graphene film 100 when removed from the mold.

[0091] Furthermore, by using vapor deposition to deposit the polymer layer, the conductive properties and mechanical properties of the graphene film can be particularly preserved upon removal of the mold. Indeed, vapor deposition allows for the application of a thin polymer coating of relatively uniform thickness that highly conforms to the roughness of the surface of the graphene film by closely following the contours of the graphene film. This polymer layer exhibits lower stress on the graphene layer than would be possible using other deposition techniques such as spin coating, given its high conformity and uniformity.

[0092] Furthermore, vapor deposition allows for the realization of a support polymer layer that strictly conforms to the three-dimensional shape of the graphene film at the nanometer and micrometer scales, respectively, contributing to the preservation of the integrity of the film by matching the wrinkles and thereby providing good conductivity and contributing to the maintenance of the global 3D shape of the graphene film after mold removal, allowing for deposition on complex shapes such as gloves, etc.

[0093] An advantage of the sensing device described herein is that the polymer coating provides a carrier layer that retains flexibility while holding the graphene electrode in place for detecting events such as keystrokes.

[0094] Having thus described at least one illustrative embodiment, various alterations, modifications, and improvements will occur to those skilled in the art.

[0095] For example, it will be apparent to those skilled in the art that although various devices including graphene have been described above and shown in the drawings, there are many alternative applications of the method of forming multilayers of graphene and polymer as described herein.

[0096] Furthermore, in alternative embodiments, various features described with respect to various embodiments can be combined in any combination.

[0097] Such alterations, modifications, and improvements are intended to be within the scope of the application. Accordingly, though described in detail above, the descriptions are not intended to limit the present application. The application is limited only by the following claims and the equivalents thereof.

Claims

1. A method for forming a graphene device, the method comprising: forming a graphene film (100) on a substrate (204); depositing a polymer material covering the surface of the graphene film (100) by vapor deposition; and The substrate (204) is removed from the graphene film (100), wherein the polymer material forms a support (102) for the graphene film (100).

2. The method of claim 1, wherein the polymeric material comprises a polymer from the orthoxylene family.

3. The method of claim 1 or 2, wherein the polymer material comprises parylene.

4. The method according to any one of claims 1 to 3, wherein the polymer layer is deposited to have a thickness between 10 nm and 5 mm.

5. The method according to any one of claims 1 to 4, wherein the graphene film (100) is formed on a three-dimensional surface of the substrate (204).

6. The method according to any one of claims 1 to 5, wherein removing the substrate (204) from the graphene film (100) is performed by an electrochemical delamination method or using acid etching.

7. Method according to any one of claims 1 to 6, for forming a sensor device (500) to be placed on a three-dimensional shape, wherein: The substrate on which the graphene film (100) is formed includes a mold (510) having a three-dimensional shape.

8. The method according to claim 7, wherein: A mold (510) is formed of a first material and at least one region (504, 506) of a second material; During formation of the graphene film (100), graphene is selectively formed on the at least one second material region but not on the first material; and A polymer material is deposited on the graphene film (100) and at least a portion of the first material.

9. The method according to claim 7 or 8, further comprising, after removing the substrate from the graphene film, performing a further vapor deposition of a polymer material to encapsulate the graphene film (100).

10. The method according to claim 8 or 9, wherein the graphene film (100) is deposited to form a conductive track having a meandering form in the detection area (606).

11. The method according to claim 8 or 9, wherein the graphene film is deposited in the form of a first graphene sheet (806) formed in the detection area and connected to a first conductive track (802), and wherein the method further comprises: forming an additional graphene film covered by a further deposit of polymer material, wherein the additional graphene film is deposited in the form of a second graphene sheet (808); and The first graphene membrane and the second graphene membrane are assembled such that the first graphene plate and the second graphene plate (806, 808) form a capacitive interface separated by a layer (814) of polymer material in a detection region.

12. A sensor device comprising: A graphene film (100) having at least one side covered by a polymer material, wherein the polymer material has a detection element (504, 606, 806, 808) formed of the graphene film (100) on a portion of its inner surface, and the polymer material contacts and supports the graphene film (100).

13. The sensor device according to claim 12, wherein the detection element comprises a meandering conductive track formed in the detection area (606) and electrically connecting the first conductive track (602) to the second conductive track (604).

14. The sensor device according to claim 12, wherein the detection element comprises a first graphene plate and a second graphene plate (806, 808) at least partially overlapping each other, the first graphene plate (806) being connected to the first conductive track and the second graphene plate (808) being connected to the second conductive track.

15. The sensor device of claim 13 or 14, further comprising a detection circuit (608, 809) coupled to the first and second conductive tracks.

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