Sustainable sorting device and method using self-powered teng

Abstract

The present disclosure relates to a self-powered sensing element comprising a triboelectric nanogenerator (TENG) and its use in material identification and / or distinguishing between different materials or different material surfaces. The present disclosure also relates to devices comprising at least one of said sensing elements, said devices being a waste sorting device, a quality testing device or a goods receipt control device. Moreover, the present disclosure relates to a method for material identification and / or distinguishing between different materials or different material surfaces, which utilizes the sensing element(s) or device(s) of the present disclosure.

Description

SUSTAINABLE SORTING DEVICE AND METHOD USING SELF-POWERED TENGBACKGROUND

[0001] The field of the DISCLOSURE lies in sensing elements and devices for material identification and / or sorting.

[0002] The present disclosure relates to a self-powered sensing element comprising a triboelectric nanogenerator (TENG) and its use in material identification and / or distinguishing between different materials or different material surfaces.

[0003] The present disclosure also relates to devices comprising at least one of said sensing elements, said devices being a waste sorting device, a quality testing device or a goods receipt control device.

[0004] Moreover, the present disclosure relates to a method for material identification and / or distinguishing between different materials or different material surfaces, which utilizes the sensing element(s) or device(s) of the present disclosure.DESCRIPTION OF THE RELATED ART

[0005] The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.

[0006] Due to the global issues in waste management, improving old as well as searching new methods of separating / sorting wastes is not only important but crucial. So as a mean to reduce the amount of wasted materials, material recycling plays an important role. For this purpose, a degree of sorting materials in a sustainable way is required.

[0007] There are already some established technologies for separating mixed plastic, such as, identifying density differences or selective dissolution of one component of the mixture to sort. However, these methods themselves are not sustainable since they consume a lot of resources, including power and solvents, and they are only limited to some certain materials.

[0008] New means and methods are needed that are sustainable and complementary to these methods with much broader versatility in terms of materials ranging from organic e.g. plastics to inorganic materials e.g Silicon dioxide.SUMMARY

[0009] In the following, the elements of the invention will be described. These elements are listed with specific embodiments, however, it should be understood that they may be combined in any manner and in any number to create additional embodiments. The variously described examples and preferred embodiments should not be construed to limit the present invention to only the explicitly described embodiments. This description should be understood to support andencompass embodiments which combine two or more of the explicitly described embodiments or which combine the one or more of the explicitly described embodiments with any number of the disclosed and / or preferred elements. Furthermore, any permutations and combinations of all described elements in this application should be considered disclosed by the description of the present application unless the context indicates otherwise.

[0010] The present disclosure provides a self-powered sensing element for material identification and / or distinguishing between different materials or different material surfaces, said sensing element comprising a triboelectric nanogenerator (TENG), said TENG comprising(a) a first conductive electrode material layer,(b) a first triboelectric material layer, attached to (a) and, together with (a) forming a first bilayer (i),(c) a gap, and(d) a second conductive material layer.

[0011] The present disclosure provides a device for material identification and / or distinguishing between materials or different material surfaces, said device comprising at least one sensing element according to the present disclosure, further comprising means for recording a triboelectric signal of the material to be identified and / or distinguished, and means for moving, tapping, contact separation, touching, rubbing, vibrating, sliding, shaking or otherwise mechanically accelerating the sensing element so as to allow any material to be identified and / or distinguished, that is contained within said sensing element, to become temporarily accommodated within said gap (c), and to allow said material to come into sequential or concomitant contact with either said first triboelectric material layer (b) and said second conductive material layer (d) as defined herein; or said first triboelectric material layer (b) and said second triboelectric material layer (e) as defined herein.

[0012] The present disclosure provides the use of the sensing element according to the present disclosure, or the device according to the present disclosure for material identification, distinction and / or sorting, wherein the use comprises comparing a triboelectric signal of the material to be identified and / or distinguished with a triboelectric signal of at least one known material, wherein said comparing of the triboelectric signals occurs preferably by means of the wave form, magnitude and / or polarity of the respective triboelectric signal.

[0013] The present disclosure provides a method for material identification and / or distinguishing between different materials or different material surfaces, comprising the steps of(1) providing at least one sensing element according to the present disclosure, or the device according to the present disclosure;(2) applying a test material, which is the material to be identified and / or distinguished, to at least one sensing element;(3) moving, tapping, contact separation, touching, rubbing, vibrating, sliding, shaking or otherwise mechanically accelerating the sensing element so as to allow the test material, that is contained within said sensing element, to become temporarily accommodated within said gap (c), and to allow said test material to come into sequential or concomitant contact with either- said first triboelectric material layer (b) and said second conductive material layer (d) as defined herein; or- said first triboelectric material layer (b) and said second triboelectric material layer (e) as defined herein;(4) recording the triboelectric signal of the test material;(5) comparing the triboelectric signal recorded in step (4) with a triboelectric signal of at least one known material, wherein in case the triboelectric signal recorded in step (4) is similar or associated to the triboelectric signal of the known material, the test material is identified to be the known material.

[0014] The foregoing paragraphs have been provided by way of general introduction and are not intended to limit the scope of the following claims. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0016] Figure 1A shows shows embodiments of sensing elements according to the present disclosure, wherein the TENG has the geometry of a sandwich. The embodiments can be used in all the modes shown in figures IB, 1C, ID, IE

[0017] Figures IB to IE show embodiments of sensing elements according to the present disclosure, wherein the TENG has the geometry of a sandwich and wherein

[0018] in Figure IB the interaction with the test material is by tapping in different modes;

[0019] in Figure 1C the interaction with the test material is by sliding in different modes;

[0020] in Figure ID the interaction with the test material is by moving to and fro in different modes; and

[0021] in Figure IE the interaction with the test material is by vibrating in different modes.

[0022] Figure 2A shows embodiments of sensing elements according to the present disclosure, wherein the TENG has the geometry of a sandwich, a bipartite grid or a plurality of bipartite grids (also called an array).

[0023] Figure 2B shows embodiments of sensing elements according to the present disclosure, wherein the TENG has the geometry of an arrangment of a ratable first roller and a rotatable second roller, or a cascade arrangment.

[0024] Figure 2C shows embodiments of sensing elements according to the present disclosure, wherein the TENG has the geometry of an arrangment including a rotable first roller, a rotatable second roller, and a rotatable conveyer.

[0025] Figure 3 shows embodiments of sensing elements according to the present disclosure, wherein the TENG has different geometries of a sandwich which is either formed by a first bilayer, a gap and one conductive material layer, or by a first bilayer, a gap and a second bilayer. The conductive electrodes, triboelectric materials, can be the same, as each other, or different from each other. The possible combinations are shown for the sandwich structure.

[0026] Figure 4A shows the embodiment of a sensing element according to the present disclosure, wherein the TENG has the geometry of a sandwich, and its interaction with the test material by opening and tapping.

[0027] Figure 4B shows the embodiment of a sensing element according to the present disclosure, wherein the TENG has the geometry of a gripper or a pair of pliers, and its interaction with the test material by opening and gripping.

[0028] Figure 5 shows the test setup and the triboelectrical signals obtained for tested materials of Example 1.

[0029] Figure 6 shows the triboelectrical signals for the tested materials of Example 2.

[0030] Figures 7A and 7B show the triboelectrical signals for the tested materials of Example 3.

[0031] Figures 8 shows the triboelectrical signals for the tested materials of Example 4.

[0032] Figures 9A and 9B show the triboelectrical signals for the tested materials of Example 5.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] As discussed above, the present disclosure provides a self-powered sensing element for material identification and / or distinguishing between different materials or different material surfaces, said sensing element comprising a triboelectric nanogenerator (TENG).

[0034] Said TENG comprises(a) a first conductive electrode material layer,(b) a first triboelectric material layer, attached to (a) and, together with (a) forming a first bilayer (i),(c) a gap, and(d) a second conductive material layer.

[0035] In the present disclosure this TENG is also referred to as TENG 1.

[0036] In one embodiment, said gap (c) is situated between said first triboelectric material layer (b) and said second conductive material layer (d) and wherein said gap (c) is configured to accommodate a material to be identified and / or distinguished and to allow said material to come into sequential or concomitant contact with said first triboelectric material layer (b) and said second conductive material layer (d).

[0037] In one embodiment, said TENG comprises a second triboelectric material. In the present disclosure this TENG is also referred to as TENG 2.

[0038] In said embodiment, the TENG preferably comprises the following structure(a) a first conductive electrode material layer,(b) a first triboelectric material layer, attached to (a) and, together with (a) forming a first bilayer (i),(c) a gap,(d) a second conductive material layer, and.(e) a second triboelectric material layer, attached to (d) and, together with (d) forming a second bilayer (ii).

[0039] In one embodiment, said gap (c) is situated between said first triboelectric material layer (b) and said second triboelectric material layer (e) and wherein said gap (c) is configured to accommodate a material to be identified and / or distinguished and to allow said material to come into sequential or concomitant contact with said first triboelectric material layer (b) and said second triboelectric material layer (e).

[0040] Examples of possible modes of interaction of a material to be identified and / or distinguished with a sensing element according to the present disclosure are shown in Figures IB to IE.

[0041] Said TENG can have different geometries. Said geometries can be a sandwich, a plurality of sandwiches, a gripper or pair of pliers, a bipartite grid, a plurality of bipartite grids, a cascade arrangement, a plurality of cascade arrangements, an arrangement of a rotatable first roller and a rotatable second roller or combinations thereof.

[0042] In one embodiment, the TENG has the geometry of a sandwich which is formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined herein, see TENG 1. The gap (c) is situated between the first triboelectric material layer (b) of said first bilayer (i) and said second conductive material layer (d).

[0043] In one embodiment, the TENG has the geometry of a sandwich formed by the first bilayer (i), the gap (c) and the second bilayer (ii), as defined herein, see TENG 2. The gap (c) being situated between the first triboelectric material layer (b) of said first bilayer (i) and the second triboelectric material layer (e) of said second bilayer (ii).

[0044] In one embodiment, the TENG has the geometry of a plurality of said sandwiches.

[0045] Examples of sandwich geometries are shown in Figures 1, 2A and 3.

[0046] In one embodiment, the TENG has the geometry of a gripper or a pair of pliers, having two opposing tongs or pliers. One of said tongs or pliers is formed by the first bilayer (i) as defined herein, see TENG 7, and the other tong or plier is formed by the second conductive material (d) as defined herein. The gap (c) is situated between the two opposing pliers or tongs.

[0047] In one embodiment, the TENG has the geometry of a gripper or a pair of pliers, having two opposing tongs or pliers. One of said tongs or pliers is formed by the first bilayer (i) as defined herein, see TENG 2. and the other tong or plier is formed by the second bilayer (ii) as defined herein. The gap (c) is situated between the two opposing pliers or tongs.

[0048] An example of a gripper geometry is shown in Figure 4B.

[0049] In one embodiment, the TENG has the geometry of a bipartite grid formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined herein, see TENG 1. In such grid, the first bilayer (i) and the second conductive material layer (d) are arranged next to each other in a co-planar fashion. The gap (c) is formed by a space above the first triboelectric material layer (b) of said first bilayer (i) and above said second conductive material layer (d). Said gap (c) allows a material to be identified and / or distinguished to come into sequential contact with said first triboelectric material layer (b) and said second conductive material layer(d), when said material to be identified and / or distinguished is moved from said first triboelectric material layer (b) to said second conductive material layer (d).

[0050] In one embodiment, the TENG has the geometry of a bipartite grid formed by the first bilayer (i), the gap (c) and the second bilayer (ii), as defined herein, see TENG 2. In such grid, the first bilayer (i) and the second bilayer (ii) are arranged next to each other in a co-planar fashion. The gap (c) is formed by a space above the first triboelectric material layer (b) of said first bilayer (i) and above the second triboelectric material layer (e) of said second bilayer (ii). Said gap (c) allows a material to be identified and / or distinguished to come into sequential contact with said first triboelectric material layer (b) and said second triboelectric material layer(e), when said material to be identified and / or distinguished is moved from said first triboelectric material layer (b) to said second triboelectric material layer (e).

[0051] In one embodiment, the TENG has the geometry of a plurality of bipartite grids, as defined herein above. Said bipartite grids are arranged next to each other in a co-planar fashion, and furthermore are arranged such that: either said plurality extends in at least one direction in a linear manner, or said plurality extends in two directions in a planar manner; said plurality of bipartite grids thus forming a multipartite grid. A multipartite grid can also be called an array.

[0052] Examples of bipartite grid geometries are shown in Figure 2A.

[0053] The bipartite grid geometries and array geometries can be used for conveyer belts and sorting lines.

[0054] In one embodiment, the TENG has the geometry of a cascade arrangement formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined herein, see TENG 1. In such cascade, the first bilayer (i) and the second conductive material layer (d) are arranged next to each other in a non-co-planar fashion at an angle such that a material to be identified and / or distinguished can come into sequential contact with said first triboelectric material layer (b) and said second conductive material layer (d), or vice versa, by bouncing off said first triboelectric material layer (b) or said second conductive material layer (d), respectively, and by subsequently contacting said second conductive material layer (d) or said first triboelectric material layer (b), respectively.

[0055] In one embodiment, the TENG has the geometry of a cascade arrangement formed by the first bilayer (i), the gap (c) and the second bilayer (ii), as defined herein, see TENG 2. In such cascade, the first bilayer (i) and the second bilayer (ii) are arranged next to each other in a non- co-planar fashion at an angle such that a material to be identified and / or distinguished can come into sequential contact with said first triboelectric material layer (b) and said second triboelectric material layer (e), or vice versa, by bouncing off said first triboelectric material layer (b) or saidsecond triboelectric material layer (e), respectively, and by subsequently contacting said second triboelectric material layer (e) or said first triboelectric material layer (b), respectively.

[0056] In one embodiment, the TENG has the geometry of a plurality of cascade arrangements, as defined herein above.

[0057] An example of a cascade arrangement is shown in Figure 2B.

[0058] The plurality of cascade arrangements preferably allows to identify and sort the material after each step of the cascade (after each cascade arrangement).

[0059] In one embodiment, the TENG has the geometry of an arrangement of a rotatable first roller and a rotatable second roller next to, but not touching each other, and having parallel axes of rotation. Each of said first roller and said second roller has a defined length, a defined circumference, and a defined lateral surface. Each of said defined lateral surfaces is subdivided into a plurality of separate regions, preferably in strips along said length of the respective roller; wherein some or all of said separate regions are formed or covered by: a first bilayer (i) and / or a second conductive material layer (d), as defined herein, see TENG 1; or a first bilayer (i) and / or a second bilayer (ii), as defined herein, see TENG 2.The forming or covering by a bilayer occurs in such a manner that the respective triboelectric material layer comes to be exposed to the surroundings of the respective roller. Said said gap (c) is formed by a space between said first roller and said second roller; wherein upon rotation of said rollers, different separate regions of said first roller come to lie opposite to and face different separate regions of said second roller, thus forming a temporary TENG as defined herein, see TENG 1 or TENG 2.

[0060] The first and second roller can turn clockwise to each other or anticlockwise. The roller arrangement can be used for hysteresis sorting.

[0061] In one embodiment, the TENG has the geometry of a plurality of roller arrangements, as defined herein above, wherein at least one rotatable roller is a rotatable conveyer.

[0062] An example of an arrangement with a first and a second rotatable roller is shown in Figure 2B.

[0063] An example of an arrangement with a first and a second rotatable roller and a rotatable conveyer is shown in Figure 2C.

[0064]

[0065] Said TENG can have different geometries, which are selected from the group comprising: i. a sandwich formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined herein, see TENG 1 the gap (c) being situated between the first triboelectric material layer (b) of said first bilayer (i) and said second conductive material layer (d); ii. a sandwich formed by the first bilayer (i), the gap (c) and the second bilayer (ii), as defined herein, see TENG 2; the gap (c) being situated between the first triboelectricmaterial layer (b) of said first bilayer (i) and the second triboelectric material layer (e) of said second bilayer (ii); iii. a plurality of sandwiches, as defined in i. and / or ii.; iv. a gripper or a pair of pliers, having two opposing tongs or pliers, wherein one of said tongs or pliers is formed by the first bilayer (i) as defined herein, see TENG 7, and the other tong or plier is formed by the second conductive material (d) as defined in (1), the gap (c) being situated between the two opposing pliers or tongs; v. a gripper or a pair of pliers, having two opposing tongs or pliers, wherein one of said tongs or pliers is formed by the first bilayer (i) as defined herein, see TENG 2. and the other tong or plier is formed by the second bilayer (ii) as defined in (2), the gap (c) being situated between the two opposing pliers or tongs; vi. a bipartite grid formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined herein, see TENG 1; wherein in such grid, the first bilayer (i) and the second conductive material layer (d) are arranged next to each other in a coplanar fashion, and the gap (c) is formed by a space above the first triboelectric material layer (b) of said first bilayer (i) and above said second conductive material layer (d); said gap (c) allowing a material to be identified and / or distinguished to come into sequential contact with said first triboelectric material layer (b) and said second conductive material layer (d), when said material to be identified and / or distinguished is moved from said first triboelectric material layer (b) to said second conductive material layer (d); vii. a bipartite grid formed by the first bilayer (i), the gap (c) and the second bilayer (ii), as defined herein, see TENG 2; wherein in such grid, the first bilayer (i) and the second bilayer (ii) are arranged next to each other in a co-planar fashion, and the gap (c) is formed by a space above the first triboelectric material layer (b) of said first bilayer (i) and above the second triboelectric material layer (e) of said second bilayer (ii); said gap (c) allowing a material to be identified and / or distinguished to come into sequential contact with said first triboelectric material layer (b) and said second triboelectric material layer (e), when said material to be identified and / or distinguished is moved from said first triboelectric material layer (b) to said second triboelectric material layer (e); viii. a plurality of bipartite grids, as defined in vi. and / or vii., said bipartite grids being arranged next to each other in a co-planar fashion, and furthermore being arranged such that: either said plurality extends in at least one direction in a linear manner, or said plurality extends in two directions in a planar manner; said plurality of bipartite grids thus forming a multipartite grid; ix. a cascade arrangement formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined herein, see TENG 1 wherein in such cascade, the first bilayer (i) and the second conductive material layer (d) are arranged next to each other in a non-co-planar fashion at an angle such that a material to be identified and / or distinguished can come into sequential contact with said first triboelectric material layer (b) and said second conductive material layer (d), or vice versa, by bouncing off said first triboelectric material layer (b) or said second conductive material layer (d), respectively,and by subsequently contacting said second conductive material layer (d) or said first triboelectric material layer (b), respectively; x. a cascade arrangement formed by the first bilayer (i), the gap (c) and the second bilayer (ii), as defined herein, see TENG 2; wherein in such cascade, the first bilayer (i) and the second bilayer (ii) are arranged next to each other in a non-co-planar fashion at an angle such that a material to be identified and / or distinguished can come into sequential contact with said first triboelectric material layer (b) and said second triboelectric material layer (e), or vice versa, by bouncing off said first triboelectric material layer (b) or said second triboelectric material layer (e), respectively, and by subsequently contacting said second triboelectric material layer (e) or said first triboelectric material layer (b), respectively; xi. a plurality of cascade arrangements, as defined in ix. and / or x.; xii. an arrangement of a rotatable first roller and a rotatable second roller next to, but not touching each other, and having parallel axes of rotation, each of said first roller and said second roller having a defined length, a defined circumference, and a defined lateral surface; wherein each of said defined lateral surfaces is subdivided into a plurality of separate regions, preferably in strips along said length of the respective roller; wherein some or all of said separate regions are formed or covered by: a first bilayer (i) and / or a second conductive material layer (d), as defined herein, see TENG 1 ; or by a first bilayer (i) and / or a second bilayer (ii), as defined herein, see TENG 2; wherein forming or covering by a bilayer occurs in such a manner that the respective triboelectric material layer comes to be exposed to the surroundings of the respective roller; and wherein said gap (c) is formed by a space between said first roller and said second roller; wherein upon rotation of said rollers, different separate regions of said first roller come to lie opposite to and face different separate regions of said second roller, thus forming a temporary TENG as defined herein, see TENG 1 or TENG 2; and xiii. a plurality of rotatable roller arrangements, as defined in xii., wherein at least one rotatable roller is a rotatable conveyer.

[0066] In one embodiment, the TENG further comprises a third conductive material layer and a third triboelectric material layer.

[0067] Examples for a TENG - in sandwich, bipartite grid, plurality of bipartite grids, cascade, first and second rotatable roller, as well as rotatable roller(s) and conveyer - with different embodiments of first, second and third triboelectric material layers and first, second and third conductive material layers are shown in Figures 2A to 2C.

[0068] In one embodiment, the first, second and, optionally, third conductive material are the same or different.

[0069] The first, second and, optionally, third conductive material can be selected from- metals, such as Cu, and / or- oxides, such as indium tin oxide (ITO), and / or- conductive materials, such as graphene, and / or- conductive polymers, such as PEDOT-PSS.

[0070] In one embodiment, the first, second and, optionally, third triboelectric material are the same or different.

[0071] The first, second and, optionally, third triboelectric material can be electron acceptor materials or electron donor materials.

[0072] In one embodiment, the triboelectric material(s) are selected from- organic materials, preferably dielectric polymers such as polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polystyrene (PS), poly methyl methacrylate (PMMA), polyethylene (PE) (such as linear low-density polyethylene (LLDPE)), polyvinyl chloride (PVC), polyvinyl butyral (PVB), polyvinyl alcohol (PVA), polyacrylonitrile, polyallylamine, poly(4-vinylpyridine), polypyridine, polydimethylsiloxane (PDMS), polyamide (PA), polycarbonate (PC) including their copolymers ; and / or- textiles, such as silk, wool, cotton and synthetic fibers; and / or- metals, such as Ag, Au, Al; and / or- inorganic materials, such as SiCE, indium tin oxide (ITO).

[0073] Examples for a TENG in sandwich geometry with different embodiments of first and second triboelectric material layers and first and second conductive material layers are shown in Figure 3.

[0074] In one embodiment, the sensing element, preferably said TENG, further comprises a material to be identified and / or distinguished.

[0075] The material to be identified and / or distinguished can be an organic material, textile, metal, inorganic material or a mixture thereof.

[0076] The terms “material to be identified and / or distinguished” and “test material” and “material to be tested” are used interchangeably throughout this disclosure, and all refer to the material which is to be applied to the TENG of the sensing elements and which is to be identified and / or distinguished.

[0077] Examples of possible modes of interaction of a material to be identified and / or distinguished with a sensing element according to the present disclosure are shown in Figures IB to IE for a TENG with sandwich geometry.

[0078] The material to be identified and / or distinguished can have different forms, such as pellet or granulate, flake, powder, film or foil, thin top coat, fabric, threads.

[0079] The material to be identified and / or distinguished can also have different surfaces, such as different surface finishes, e.g. e.g. rough, spikey, smooth.

[0080] As discussed above, the present disclosure provides a device for material identification and / or distinguishing between materials or different material surfaces.

[0081] Said device comprises at least one sensing element according to the present disclosure.

[0082] Said device further comprisesmeans for recording a triboelectric signal of the material to be identified and / or distinguished, and means for moving, tapping, contact separation, touching, rubbing, vibrating, sliding, shaking or otherwise mechanically accelerating the sensing element.

[0083] Said means for moving, tapping, contact separation, touching, rubbing, vibrating, sliding, shaking or otherwise mechanically accelerating the sensing element are there to allow any material to be identified and / or distinguished, that is contained within said sensing element, to become temporarily accommodated within said gap (c), and to allow said material to come into sequential or concomitant contact with either- said first triboelectric material layer (b) and said second conductive material layer (d) as defined herein, see TENG 1 ; or- said first triboelectric material layer (b) and said second triboelectric material layer (e) as defined herein, see TENG 2.

[0084] In one embodiment, the device further comprises means for sorting materials after identification.

[0085] As discussed above, the present disclosure provides the use of a sensing element according to the present disclosure, or the device according to the present disclosure for material identification, distinction and / or sorting.

[0086] The use comprises comparing a triboelectric signal of the material to be identified and / or distinguished with a triboelectric signal of at least one known material.

[0087] In one embodiment, the use comprises comparing a triboelectric signal of the material to be identified and / or distinguished with triboelectric signals of a plurality of known materials. Said triboelectric signals of a plurality of known materials can also be called triboelectric signals of a library of known materials or a material library.

[0088] In one embodiment, the comparing of the triboelectric signals occurs by means of the wave form, magnitude and / or polarity of the respective triboelectric signal.

[0089] In one embodiment, the comparing of the triboelectric signals is carried out by using pattern recognition, machine learning and / or artificial intelligence (Al) techniques.

[0090] In one embodiment, the use comprises distinguishing and, optionally, separating the materials depending on their different surfaces, such as different surface finishes, e.g. rough, spikey, smooth.

[0091] As discussed above, the present disclosure provides a device for material identification and / or distinguishing between materials or different material surfaces.

[0092] A device according to the present disclosure can be a waste sorting device.

[0093] A waste sorting device according to the present disclosure can be for separating plastic waste and / or for obtaining pure grade plastics. A waste sorting device according to the presentdisclosure can be for separating plastic waste from metal(s). A waste sorting device according to the present disclosure can be for obtaining sorted metal(s).

[0094] A device according to the present disclosure can be a quality testing device for rapid testing. Such device can be in assembly lines.

[0095] A device according to the present disclosure can be a goods receipt control device. Such device can be for rapid control of incoming goods.

[0096] A device according to the present disclosure can be a metal-waste separating device.

[0097] A device according to the present disclosure can be a material recycling device.

[0098] As discussed above, the present disclosure provides the use of a sensing element according to the present disclosure, or the device according to the present disclosure.

[0099] Such use can be separating plastic waste and obtaining sorted plastic material or pure grade plastics.

[0100] Such use can be separating plastic waste from metal(s).

[0101] Such use can be separating metal(s) from waste and obtaining sorted metal(s).

[0102] Such use can be separating textile(s) waste and obtaining sorted textile type.

[0103] Such use can be rapid testing for quality assurance, e.g. in assembly lines.

[0104] Such use can be rapid goods receipt control.

[0105] As discussed above, the present disclosure provides a method for material identification and / or distinguishing between different materials or different material surfaces.

[0106] Said method comprises the steps of(1) providing at least one sensing element according to the present disclosure, or a device according to the present disclosure;(2) applying a test material, which is the material to be identified and / or distinguished, to at least one sensing element;(3) moving, tapping, contact separation, touching, rubbing, vibrating, sliding, shaking or otherwise mechanically accelerating the sensing element so as to allow the test material, that is contained within said sensing element, to become temporarily accommodated within said gap (c), and to allow said test material to come into sequential or concomitant contact with either- said first triboelectric material layer (b) and said second conductive material layer (d) as defined herein in TENG 1 ; or- said first triboelectric material layer (b) and said second triboelectric material layer (e) as defined herein in TENG 2;(4) recording the triboelectric signal of the test material;(5) comparing the triboelectric signal recorded in step (4) with a triboelectric signal of at least one known material, wherein in case the triboelectric signal recorded in step (4) is similar or associated to the triboelectric signal of the known material, the test material is identified to be the known material.

[0107] In one embodiment, in step (5) the triboelectric signal recorded in step (4) is compared with triboelectric signals of a plurality of known materials,and wherein the test material is identified as the known material whose triboelectric signal is the most similar or associated to the triboelectric signal recorded in step (4).

[0108] In one embodiment, said comparing of the triboelectric signals in step (5) is carried out by using pattern recognition, machine learning and / or artificial intelligence (Al) techniques.

[0109] For example, pattern recognition as method to extract information from a sensor can be carried out as described in US 2013 / 064423 Al.

[0110] In one embodiment, the triboelectric signal recorded in step (4) is compared in step (5) with reference to wave form, magnitude and / or polarity of the respective triboelectric signal(s).

[0111] In one embodiment, the test material is an organic material, textile, metal, inorganic material or a mixture thereof, and can have different forms, such as pellet or granulate, flake, powder, film or foil, thin top coat, fabric, threads.

[0112] In one embodiment, the test material has different surfaces, such as different surface finishes, e.g. e.g. rough, spikey, smooth.

[0113] In one embodiment, test material is waste and the method further comprises the step (6) sorting the material.

[0114] Note that the present technology can also be configured as described below.(1) A self-powered sensing element for material identification and / or distinguishing between different materials or different material surfaces, said sensing element comprising a triboelectric nanogenerator (TENG), said TENG comprising(a) a first conductive electrode material layer,(b) a first triboelectric material layer, attached to (a) and, together with (a) forming a first bilayer (i),(c) a gap, and(d) a second conductive material layer.(2) The sensing element of (1), wherein said TENG comprises a second triboelectric material, wherein the TENG preferably comprises the following structure(a) a first conductive electrode material layer,(b) a first triboelectric material layer, attached to (a) and, together with (a) forming a first bilayer (i),(c) a gap,(d) a second conductive material layer, and.(e) a second triboelectric material layer, attached to (d) and, together with (d) forming a second bilayer (ii).(3) The sensing element of (1) or (2), wherein said gap (c) is situated either- between said first triboelectric material layer (b) and said second conductive material layer (d) in a TENG as defined in (1); or- between said first triboelectric material layer (b) and said second triboelectric material layer (e) in a TENG as defined in (2); and wherein said gap (c) is configured to accommodate a material to be identified and / or distinguished and to allow said material to come into sequential or concomitant contact with either- said first triboelectric material layer (b) and said second conductive material layer (d) in said TENG as defined in (1); or- said first triboelectric material layer (b) and said second triboelectric material layer (e) in said TENG as defined in (2).(4) The sensing element of any one of (1) to (3), wherein said TENG has a geometry selected from the group comprising: i. a sandwich formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined in (1); the gap (c) being situated between the first triboelectric material layer (b) of said first bilayer (i) and said second conductive material layer (d); ii. a sandwich formed by the first bilayer (i), the gap (c) and the second bilayer (ii), as defined in (2); the gap (c) being situated between the first triboelectric material layer (b) of said first bilayer (i) and the second triboelectric material layer (e) of said second bilayer (ii); iii. a plurality of sandwiches, as defined in i. and / or ii.; iv. a gripper or a pair of pliers, having two opposing tongs or pliers, wherein one of said tongs or pliers is formed by the first bilayer (i) as defined in (1), and the other tong or plier is formed by the second conductive material (d) as defined in (1), the gap (c) being situated between the two opposing pliers or tongs; v. a gripper or a pair of pliers, having two opposing tongs or pliers, wherein one of said tongs or pliers is formed by the first bilayer (i) as defined in (2), and the other tong or plier is formed by the second bilayer (ii) as defined in (2), the gap (c) being situated between the two opposing pliers or tongs; vi. a bipartite grid formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined in (1); wherein in such grid, the first bilayer (i) and the second conductive material layer (d) are arranged next to each other in a co-planar fashion, and the gap (c) is formed by a space above the first triboelectric material layer(b) of said first bilayer (i) and above said second conductive material layer (d); said gap(c) allowing a material to be identified and / or distinguished to come into sequential contact with said first triboelectric material layer (b) and said second conductive material layer (d), when said material to be identified and / or distinguished is moved from said first triboelectric material layer (b) to said second conductive material layer (d); vii. a bipartite grid formed by the first bilayer (i), the gap (c) and the second bilayer (ii), as defined in (2); wherein in such grid, the first bilayer (i) and the second bilayer (ii) arearranged next to each other in a co-planar fashion, and the gap (c) is formed by a space above the first triboelectric material layer (b) of said first bilayer (i) and above the second triboelectric material layer (e) of said second bilayer (ii); said gap (c) allowing a material to be identified and / or distinguished to come into sequential contact with said first triboelectric material layer (b) and said second triboelectric material layer (e), when said material to be identified and / or distinguished is moved from said first triboelectric material layer (b) to said second triboelectric material layer (e); viii. a plurality of bipartite grids, as defined in vi. and / or vii., said bipartite grids being arranged next to each other in a co-planar fashion, and furthermore being arranged such that: either said plurality extends in at least one direction in a linear manner, or said plurality extends in two directions in a planar manner; said plurality of bipartite grids thus forming a multipartite grid; ix. a cascade arrangement formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined in (1); wherein in such cascade, the first bilayer(i) and the second conductive material layer (d) are arranged next to each other in a non- co-planar fashion at an angle such that a material to be identified and / or distinguished can come into sequential contact with said first triboelectric material layer (b) and said second conductive material layer (d), or vice versa, by bouncing off said first triboelectric material layer (b) or said second conductive material layer (d), respectively, and by subsequently contacting said second conductive material layer (d) or said first triboelectric material layer (b), respectively; x. a cascade arrangement formed by the first bilayer (i), the gap (c) and the second bilayer(ii), as defined in (2); wherein in such cascade, the first bilayer (i) and the second bilayer (ii) are arranged next to each other in a non-co-planar fashion at an angle such that a material to be identified and / or distinguished can come into sequential contact with said first triboelectric material layer (b) and said second triboelectric material layer (e), or vice versa, by bouncing off said first triboelectric material layer (b) or said second triboelectric material layer (e), respectively, and by subsequently contacting said second triboelectric material layer (e) or said first triboelectric material layer (b), respectively; xi. a plurality of cascade arrangements, as defined in ix. and / or x.; xii. an arrangement of a rotatable first roller and a rotatable second roller next to, but not touching each other, and having parallel axes of rotation, each of said first roller and said second roller having a defined length, a defined circumference, and a defined lateral surface; wherein each of said defined lateral surfaces is subdivided into a plurality of separate regions, preferably in strips along said length of the respective roller; wherein some or all of said separate regions are formed or covered by: a first bilayer (i) and / or a second conductive material layer (d), as defined in (1); or by a first bilayer (i) and / or a second bilayer (ii), as defined in (2); wherein forming or covering by a bilayer occurs in such a manner that the respective triboelectric material layer comes to be exposed to the surroundings of the respective roller; and wherein said gap (c) is formed by a space between said first roller and said second roller; wherein upon rotation of said rollers, different separate regions of said first roller come to lie opposite to and face differentseparate regions of said second roller, thus forming a temporary TENG as defined in (1) or (2); and xiii. a plurality of rotatable roller arrangements, as defined in xii., wherein at least one rotatable roller is a rotatable conveyer.(5) The sensing element of any one of (1) to (4), wherein said TENG further comprises a third conductive material layer and a third triboelectric material layer.(6) The sensing element of any one of the foregoing embodiments, wherein said sensing element, preferably said TENG, further comprises a material to be identified and / or distinguished.(7) The sensing element of any one of the foregoing embodiments, wherein the first, second and, optionally, third conductive material are the same or different, and are preferably selected from metals, such as Cu, and / or oxides, such as indium tin oxide (ITO), and / or conductive materials, such as graphene, and / or conductive polymers, such as PEDOT-PSS.(8) The sensing element of any of the foregoing embodiments, wherein the first, second and, optionally, third triboelectric material are the same or different, and are preferably electron acceptor materials or electron donor materials.(9) The sensing element of (8), wherein the triboelectric material(s) are selected from- organic materials, preferably dielectric polymers such as polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polystyrene (PS), poly methyl methacrylate (PMMA), polyethylene (PE) (such as linear low-density polyethylene (LLDPE)), polyvinyl chloride (PVC), polyvinyl butyral (PVB), polyvinyl alcohol (PVA), polyacrylonitrile, polyallylamine, poly(4-vinylpyridine), polypyridine, polydimethylsiloxane (PDMS), polyamide (PA), polycarbonate (PC) including their copolymers ; and / or- textiles, such as silk, wool, cotton and synthetic fibers; and / or- metals, such as Ag, Au, Al; and / or- inorganic materials, such as SiOi, indium tin oxide (ITO).(10) The sensing element of any one of (1) to (9), wherein the material to be identified and / or distinguished is an organic material, textile, metal, inorganic material or a mixture thereof, and can have different forms, such as pellet or granulate, flake, powder, film or foil, thin top coat, fabric, threads, and / or wherein the material to be identified and / or distinguished has different surfaces, such as different surface finishes, e.g. e.g. rough, spikey, smooth.(11) A device for material identification and / or distinguishing between materials or different material surfaces, said device comprising at least one sensing element of any one of (1) to (10), further comprising means for recording a triboelectric signal of the material to be identified and / or distinguished, and means for moving, tapping, contact separation, touching, rubbing, vibrating, sliding, shaking or otherwise mechanically accelerating the sensing element so as to allow any material to be identified and / or distinguished, that is contained within said sensing element, to become temporarily accommodated within said gap (c), and to allow said material to come into sequential or concomitant contact with either- said first triboelectric material layer (b) and said second conductive material layer (d) as defined (1); or- said first triboelectric material layer (b) and said second triboelectric material layer (e) as defined (2).(12) The device of (11), further comprising means for sorting materials after identification.(13) Use of the sensing element of any one of (1) to (10), or the device of (11) or (12) for material identification, distinction and / or sorting, wherein the use comprises comparing a triboelectric signal of the material to be identified and / or distinguished with a triboelectric signal of at least one known material, wherein said comparing of the triboelectric signals occurs preferably by means of the wave form, magnitude and / or polarity of the respective triboelectric signal.(14) The use of (13), wherein a triboelectric signal of the material to be identified and / or distinguished is compared with triboelectric signals of a plurality of known materials.(15) The use of (13) or (14), wherein said comparing of the triboelectric signals is carried out by using pattern recognition, machine learning and / or artificial intelligence (Al) techniques.16. The use of any one of (13) to (15), comprising distinguishing and, optionally, separating the materials depending on their different surfaces, such as different surface finishes, e.g. rough, spikey, smooth.(17) The device of (11) or (12), which is a- waste sorting device, in particular for separating plastic waste and for obtaining pure grade plastics, or for separating plastic waste from metal(s) and for obtaining sorted metal(s),- a quality testing device for rapid testing, e.g. in assembly lines,- a goods receipt control device for rapid control of incoming goods,- a metal-waste separating device,- a material recycling device.(18) Use of the device of (17) or the use of any one of (13) to (16), for- separating plastic waste and obtaining sorted plastic material or pure grade plastics,- separating plastic waste from metal(s),- separating metal(s) from waste and obtaining sorted metal(s),- separating textile(s) waste and obtaining sorted textile type,- rapid testing for quality assurance, e.g. in assembly lines,- rapid goods receipt control(19) A method for material identification and / or distinguishing between different materials or different material surfaces, comprising the steps of1) providing at least one sensing element of any one of (1) to (10), or a device of (11) or (12);2) applying a test material, which is the material to be identified and / or distinguished, to at least one sensing element;3) moving, tapping, contact separation, touching, rubbing, vibrating, sliding, shaking or otherwise mechanically accelerating the sensing element so as to allow the test material, that is contained within said sensing element, to become temporarily accommodated within said gap (c), and to allow said test material to come into sequential or concomitant contact with either- said first triboelectric material layer (b) and said second conductive material layer (d) as defined in (1); or- said first triboelectric material layer (b) and said second triboelectric material layer (e) as defined in (2);4) recording the triboelectric signal of the test material;5) comparing the triboelectric signal recorded in step 4) with a triboelectric signal of at least one known material, wherein in case the triboelectric signal recorded in step 4) is similar or associated to the triboelectric signal of the known material, the test material is identified to be the known material.(20) The method of (19), wherein in step 5) the triboelectric signal recorded in step 4) is compared with triboelectric signals of a plurality of known materials, and wherein the test material is identified as the known material whose triboelectric signal is the most similar or associated to the triboelectric signal recorded in step 4).(21) The method of (19) or (20), wherein the triboelectric signal recorded in step 4) is compared in step 5) with reference to wave form, magnitude and / or polarity of the respective triboelectric signal(s).(22) The method of any one of (19) to (21), wherein said comparing of the triboelectric signals in step 5) is carried out by using pattern recognition, machine learning and / or artificial intelligence (Al) techniques.(23) The method of any one of (19) to (22), wherein the test material is an organic material, textile, metal, inorganic material or a mixture thereof, and can have different forms, such as pellet or granulate, flake, powder, film or foil, thin top coat, fabric, threads, and / or wherein the test material has different surfaces, such as different surface finishes, e.g. e.g. rough, spikey, smooth.(24) The method of (23), wherein the test material is waste and the method further comprises the step6) sorting the material.

[0115] The present disclosure discloses a new complementary technique for detecting / or sorting materials in a sustainable way. The invention is based on using triboelectric nanogenerators (TENGs) as a self-powered sensing element for identification and / or sorting the materials based on their triboelectric series. In a pre-step, a TENG stack with fixed materials is required. All the materials which need to be sorted, should be used as additional triboelectric material separately to build up a library of all possible triboelectrical signals which can be generated by TENG based on these materials. Then the TENG (stack or different geometry, as defined herein) as sensor is designed in a way that when a test material is brought into contact with the fix known triboelectric materials, the obtained triboelectrical signals can be compared with the triboelectrical signals available in the material library in terms of wave form, magnitude, and polarity by preferably using pattern recognition, machine learning and Al techniques. By finding the similar triboelectrical signal characterization, the unknown touched material can be detected and identified.

[0116] The self-powered TENG detection / sorting sensor solution disclosed herein provides a sustainable complementary technique to the methods of the prior art with much broader versatility in terms of materials ranging from organic e.g plastics to inorganic materials e.g silicon dioxide. Using Al and machine learning techniques can help significantly to improve the accuracy of the detection functionality of the TENG sorting sensor.

[0117] According to the present disclosure, “similarity” of triboelectric signals or “association” of triboelectric signals is preferably determined with reference to wave form, magnitude and / or polarity of the respective triboelectric signals and / or by means of pattern recognition, machine learning and / or artificial intelligence (Al) techniques.

[0118] “Pattern recognition” as used herein refers to the process of recognizing patterns by using a machine learning algorithm. Pattern recognition can be defined as the classification of data based on knowledge already gained or on statistical information extracted from patterns and / or their representation.

[0119] For example, in a typical pattern recognition application, the raw data is processed and converted into a form that is amenable for a machine to use. Pattern recognition involves the classification and cluster of patterns. In “classification”, an appropriate class label is assigned toa pattern based on an abstraction that is generated using a set of training patterns or domain knowledge. Classification is used in supervised learning. “Clustering” generates a partition of the data which helps decision making, wherein said specific decision-making activity can be applied in the method of the present disclosure. For example, clustering is used in unsupervised learning. Features may be represented as continuous, discrete, or discrete binary variables. A feature is a function of one or more measurements, computed so that it quantifies some significant characteristics of the object.

[0120] Learning is a phenomenon through which a system gets trained and becomes adaptable to give results in an accurate manner. Learning is the most important phase as to how well the system performs on the data provided to the system depends on which algorithms are used on the data. The entire dataset is divided into two categories, one which is used in training the model i.e. Training set, and the other that is used in testing the model after training, i.e. Testing set.

[0121] Training set: The training set is used to build a model or, as in the present disclosure, a library. It consists of the set of images that are used to train the system. Training rules and algorithms are used to give relevant information on how to associate input data with output decisions. The system is trained by applying these algorithms to the dataset, all the relevant information is extracted from the data, and results are obtained.

[0122] Testing set: Testing data is used to test the system. It is the set of data that is used to verify whether the system is producing the correct output after being trained or not. Testing data is used to measure the accuracy of the system.EXAMPLESEXAMPLE 1:

[0123] A TENG stack based on cupper and ITO as the bottom and top electrodes was used. The TENG stack was in the “two materials mode”, wherein one fix triboelectric material 1, namely PET, is used and the TENG stack is filled with different test materials as the second triboelectric material 2, namely PA 66, LLDPE and SiOi, all in forms of granulates / pellets.

[0124] The stack was fixed on a vortex mechanical shaker to bring the pellets in contact with first triboelectric material and the bottom electrode by vibrating. The test setup and the electrical signals obtained for tested materials are illustrated in Figure 5.

[0125] The wave form obtained from each material has its unique characterization in terms of amplitude, magnitude, polarity, and shape.EXAMPLE 2:

[0126] A TENG stack based on cupper and ITO as the bottom and top electrodes was used. The TENG stack was in the “two materials mode”, wherein one fix triboelectric material 1, namely PET is used and the TENG stack is filled with test material as the second triboelectric material 2: PC from 2 different supplier and having different trade name all in forms of granulates / pellets .

[0127] The stack was fixed on a vortex mechanical shaker to bring the pellets in contacts with first triboelectric material and the bottom electrode by vibrating. The electrical signals obtained for the 2 tested materials are shown in Figure 6.EXAMPLE 3:

[0128] A TENG stack based on cupper and ITO as the bottom and top electrodes was used. The TENG stack was in the “two materials mode”, wherein one fix triboelectric material 1, namely PET, is used and the TENG stack is filled with test material as the second triboelectric material 2: a mixture of two different materials SiO and PA66 in forms of granulates / pellets.

[0129] The stack was fixed on a vortex mechanical shaker to bring the pellets in contacts with first triboelectric material and the bottom electrode by vibrating. The electrical signals obtained for the tested materials are shown in Figure 7.

[0130] It can be seen that the mixture of SiO and PA66 give a signal that is equivalent to the sum of the signal of the two individual single materials (Figure 7B).EXAMPLE 4:

[0131] A TENG stack based on cupper and ITO as the bottom and top electrodes was used. The TENG stack was in the “three materials mode”, wherein two fix triboelectric materials 1 and 2, namely PET and PDMS, are used and the TENG stack is filled with different test materials as the third triboelectric material, namely PC, PA 66 and LLDPE in forms of granulates / pellets (training set). The stack was fixed on a vortex mechanical shaker to bring the pellets in contacts with first triboelectric material and the second triboelectric material by vibrating. The electrical signals obtained for the tested materials are shown in Figure 8. The wave form recorded from each material has its unique characterization in terms of polarity, amplitude, magnitude, and shape.

[0132] In this subsequent stage, the materials which are already available in the library and extrapolated from the library and prior knowledge can be tested anonymously.

[0133] The TENG stack with 2 triboelectric materials is used as sensing element and will be filled with the pellets of unknown material as triboelectric material (testing set).

[0134] The electrical signal from each unknown material is recorded separately.

[0135] The recorded electrical signals are compared with the available signals for known materials in the material library to find similar signal patterns match by using pattern recognition technique.

[0136] The anonymous material is detected and sorted based on these matching results (Figure 8).EXAMPLE 5: Textile detection

[0137] Pneumatic hammer setup was adapted to TENG stack. An open TENG stack based on ITO as the bottom “anvil” and top “hammer” electrodes was used. The TENG stack was in the “three materials mode”, wherein two fix identical triboelectric materials 1 and 2, namely PET, is used and the different textile test materials placed on either hammer or the anvil as the thirdtriboelectric material, namely Wool, NITEX (Nylon-based textile) and PTFE, all in forms of textile sheets.

[0138] Pneumatic hammer setup was run to periodically bring the open TENG stack in close state.

[0139] The wave form obtained from each material has its unique characterization in terms of polarity, amplitude, magnitude, and shape as it’s shown in Figure 9 A and it can be observed better in the zoomed-in of the graphs, in Figure 9 B.

[0140] Thus, the foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure. As will be understood by those skilled in the art, the present disclosure may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present disclosure is intended to be illustrative, but not limiting of the scope of the disclosure, as well as other claims. The disclosure, including any readily discernible variants of the teachings herein, define, in part, the scope of the foregoing claim terminology such that no inventive subject matter is dedicated to the public.

Claims

CLAIMS1. A self-powered sensing element for material identification and / or distinguishing between different materials or different material surfaces, said sensing element comprising a triboelectric nanogenerator (TENG), said TENG comprising(a) a first conductive electrode material layer,(b) a first triboelectric material layer, attached to (a) and, together with (a) forming a first bilayer (i),(c) a gap, and(d) a second conductive material layer.

2. The sensing element of claim 1, wherein said TENG comprises a second triboelectric material, wherein the TENG preferably comprises the following structure(a) a first conductive electrode material layer,(b) a first triboelectric material layer, attached to (a) and, together with (a) forming a first bilayer (i),(c) a gap,(d) a second conductive material layer, and.(e) a second triboelectric material layer, attached to (d) and, together with (d) forming a second bilayer (ii).

3. The sensing element of claim 1 or 2, wherein said gap (c) is situated either- between said first triboelectric material layer (b) and said second conductive material layer (d) in a TENG as defined in claim 1; or- between said first triboelectric material layer (b) and said second triboelectric material layer (e) in a TENG as defined in claim 2; and wherein said gap (c) is configured to accommodate a material to be identified and / or distinguished and to allow said material to come into sequential or concomitant contact with either- said first triboelectric material layer (b) and said second conductive material layer (d) in said TENG as defined in claim 1; or- said first triboelectric material layer (b) and said second triboelectric material layer (e) in said TENG as defined in claim 2.

4. The sensing element of any one of claims 1 to 3, wherein said TENG has a geometry selected from the group comprising:i. a sandwich formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined in claim 1; the gap (c) being situated between the first triboelectric material layer (b) of said first bilayer (i) and said second conductive material layer (d); ii. a sandwich formed by the first bilayer (i), the gap (c) and the second bilayer (ii), as defined in claim 2; the gap (c) being situated between the first triboelectric material layer (b) of said first bilayer (i) and the second triboelectric material layer (e) of said second bilayer (ii); iii. a plurality of sandwiches, as defined in i. and / or ii.; iv. a gripper or a pair of pliers, having two opposing tongs or pliers, wherein one of said tongs or pliers is formed by the first bilayer (i) as defined in claim 1, and the other tong or plier is formed by the second conductive material (d) as defined in claim 1, the gap (c) being situated between the two opposing pliers or tongs; v. a gripper or a pair of pliers, having two opposing tongs or pliers, wherein one of said tongs or pliers is formed by the first bilayer (i) as defined in claim 2, and the other tong or plier is formed by the second bilayer (ii) as defined in claim 2, the gap (c) being situated between the two opposing pliers or tongs; vi. a bipartite grid formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined in claim 1; wherein in such grid, the first bilayer (i) and the second conductive material layer (d) are arranged next to each other in a co-planar fashion, and the gap (c) is formed by a space above the first triboelectric material layer(b) of said first bilayer (i) and above said second conductive material layer (d); said gap(c) allowing a material to be identified and / or distinguished to come into sequential contact with said first triboelectric material layer (b) and said second conductive material layer (d), when said material to be identified and / or distinguished is moved from said first triboelectric material layer (b) to said second conductive material layer (d); vii. a bipartite grid formed by the first bilayer (i), the gap (c) and the second bilayer (ii), as defined in claim 2; wherein in such grid, the first bilayer (i) and the second bilayer (ii) are arranged next to each other in a co-planar fashion, and the gap (c) is formed by a space above the first triboelectric material layer (b) of said first bilayer (i) and above the second triboelectric material layer (e) of said second bilayer (ii); said gap (c) allowing a material to be identified and / or distinguished to come into sequential contact with said first triboelectric material layer (b) and said second triboelectric material layer (e), when said material to be identified and / or distinguished is moved from said first triboelectric material layer (b) to said second triboelectric material layer (e); viii. a plurality of bipartite grids, as defined in vi. and / or vii., said bipartite grids being arranged next to each other in a co-planar fashion, and furthermore being arranged such that: either said plurality extends in at least one direction in a linear manner, or said plurality extends in two directions in a planar manner; said plurality of bipartite grids thus forming a multipartite grid; ix. a cascade arrangement formed by the first bilayer (i), the gap (c) and the second conductive material layer (d), as defined in claim 1; wherein in such cascade, the first bilayer (i) and the second conductive material layer (d) are arranged next to each other ina non-co-planar fashion at an angle such that a material to be identified and / or distinguished can come into sequential contact with said first triboelectric material layer (b) and said second conductive material layer (d), or vice versa, by bouncing off said first triboelectric material layer (b) or said second conductive material layer (d), respectively, and by subsequently contacting said second conductive material layer (d) or said first triboelectric material layer (b), respectively; x. a cascade arrangement formed by the first bilayer (i), the gap (c) and the second bilayer (ii), as defined in claim 2; wherein in such cascade, the first bilayer (i) and the second bilayer (ii) are arranged next to each other in a non-co-planar fashion at an angle such that a material to be identified and / or distinguished can come into sequential contact with said first triboelectric material layer (b) and said second triboelectric material layer (e), or vice versa, by bouncing off said first triboelectric material layer (b) or said second triboelectric material layer (e), respectively, and by subsequently contacting said second triboelectric material layer (e) or said first triboelectric material layer (b), respectively; xi. a plurality of cascade arrangements, as defined in ix. and / or x.; xii. an arrangement of a rotatable first roller and a rotatable second roller next to, but not touching each other, and having parallel axes of rotation, each of said first roller and said second roller having a defined length, a defined circumference, and a defined lateral surface; wherein each of said defined lateral surfaces is subdivided into a plurality of separate regions, preferably in strips along said length of the respective roller; wherein some or all of said separate regions are formed or covered by: a first bilayer (i) and / or a second conductive material layer (d), as defined in claim 1; or by a first bilayer (i) and / or a second bilayer (ii), as defined in claim 2; wherein forming or covering by a bilayer occurs in such a manner that the respective triboelectric material layer comes to be exposed to the surroundings of the respective roller; and wherein said gap (c) is formed by a space between said first roller and said second roller; wherein upon rotation of said rollers, different separate regions of said first roller come to lie opposite to and face different separate regions of said second roller, thus forming a temporary TENG as defined in claim 1 or 2; and xiii. a plurality of rotatable roller arrangements, as defined in xii., wherein at least one rotatable roller is a rotatable conveyer.

5. The sensing element of any one of claims 1 to 4, wherein said TENG further comprises a third conductive material layer and a third triboelectric material layer.

6. The sensing element of any one of the foregoing claims, wherein said sensing element, preferably said TENG, further comprises a material to be identified and / or distinguished.

7. The sensing element of any one of the foregoing claims, wherein the first, second and, optionally, third conductive material are the same or different,and are preferably selected from metals, such as Cu, and / or oxides, such as indium tin oxide (ITO), and / or conductive materials, such as graphene, and / or conductive polymers, such as PEDOT-PSS.

8. The sensing element of any of the foregoing claims, wherein the first, second and, optionally, third triboelectric material are the same or different, and are preferably electron acceptor materials or electron donor materials.

9. The sensing element of claim 8, wherein the triboelectric material(s) are selected from- organic materials, preferably dielectric polymers such as polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polystyrene (PS), poly methyl methacrylate (PMMA), polyethylene (PE) (such as linear low-density polyethylene (LLDPE)), polyvinyl chloride (PVC), polyvinyl butyral (PVB), polyvinyl alcohol (PVA), polyacrylonitrile, polyallylamine, poly(4-vinylpyridine), polypyridine, polydimethylsiloxane (PDMS), polyamide (PA), polycarbonate (PC) including their copolymers ; and / or- textiles, such as silk, wool, cotton and synthetic fibers; and / or- metals, such as Ag, Au, Al; and / or- inorganic materials, such as SiCE, indium tin oxide (ITO).

10. The sensing element of any one of claims 1 to 9, wherein the material to be identified and / or distinguished is an organic material, textile, metal, inorganic material or a mixture thereof, and can have different forms, such as pellet or granulate, flake, powder, film or foil, thin top coat, fabric, threads, and / or wherein the material to be identified and / or distinguished has different surfaces, such as different surface finishes, e.g. e.g. rough, spikey, smooth.

11. A device for material identification and / or distinguishing between materials or different material surfaces, said device comprising at least one sensing element of any one of claims 1 to 10, further comprising means for recording a triboelectric signal of the material to be identified and / or distinguished, and means for moving, tapping, contact separation, touching, rubbing, vibrating, sliding, shaking or otherwise mechanically accelerating the sensing element so as to allow any material to be identified and / or distinguished, that is contained within said sensing element, to become temporarily accommodated within said gap (c), and to allow said material to come into sequential or concomitant contact with either- said first triboelectric material layer (b) and said second conductive material layer (d) as defined in claim 1 ; or- said first triboelectric material layer (b) and said second triboelectric material layer (e) as defined in claim 2.

12. The device of claim 11, further comprising means for sorting materials after identification.

13. Use of the sensing element of any one of claims 1 to 10, or the device of claim 11 or 12 for material identification, distinction and / or sorting, wherein the use comprises comparing a triboelectric signal of the material to be identified and / or distinguished with a triboelectric signal of at least one known material, wherein said comparing of the triboelectric signals occurs preferably by means of the wave form, magnitude and / or polarity of the respective triboelectric signal.

14. The use of claim 13, wherein a triboelectric signal of the material to be identified and / or distinguished is compared with triboelectric signals of a plurality of known materials.

15. The use of claim 13 or 14, wherein said comparing of the triboelectric signals is carried out by using pattern recognition, machine learning and / or artificial intelligence (Al) techniques.

16. The use of any one of claims 13 to 15, comprising distinguishing and, optionally, separating the materials depending on their different surfaces, such as different surface finishes, e.g. rough, spikey, smooth.

17. The device of claim 11 or 12, which is a- waste sorting device, in particular for separating plastic waste and for obtaining pure grade plastics, or for separating plastic waste from metal(s) and for obtaining sorted metal(s),- a quality testing device for rapid testing, e.g. in assembly lines,- a goods receipt control device for rapid control of incoming goods,- a metal-waste separating device,- a material recycling device.

18. Use of the device of claim 17 or the use of any one of claims 13 to 16, for- separating plastic waste and obtaining sorted plastic material or pure grade plastics,- separating plastic waste from metal(s),- separating metal(s) from waste and obtaining sorted metal(s),- separating textile(s) waste and obtaining sorted textile type,- rapid testing for quality assurance, e.g. in assembly lines,- rapid goods receipt control19. A method for material identification and / or distinguishing between different materials or different material surfaces, comprising the steps of(1) providing at least one sensing element of any one of claims 1 to 10, or a device of claim 11 or 12;(2) applying a test material, which is the material to be identified and / or distinguished, to at least one sensing element;(3) moving, tapping, contact separation, touching, rubbing, vibrating, sliding, shaking or otherwise mechanically accelerating the sensing element so as to allow the test material, that is contained within said sensing element, to become temporarily accommodated within said gap (c), and to allow said test material to come into sequential or concomitant contact with either- said first triboelectric material layer (b) and said second conductive material layer (d) as defined in claim 1 ; or- said first triboelectric material layer (b) and said second triboelectric material layer (e) as defined in claim 2;(4) recording the triboelectric signal of the test material;(5) comparing the triboelectric signal recorded in step (4) with a triboelectric signal of at least one known material, wherein in case the triboelectric signal recorded in step (4) is similar or associated to the triboelectric signal of the known material, the test material is identified to be the known material.

20. The method of claim 19, wherein in step (5) the triboelectric signal recorded in step (4) is compared with triboelectric signals of a plurality of known materials, and wherein the test material is identified as the known material whose triboelectric signal is the most similar or associated to the triboelectric signal recorded in step (4).

21. The method of claim 19 or 20, wherein the triboelectric signal recorded in step (4) is compared in step (5) with reference to wave form, magnitude and / or polarity of the respective triboelectric signal(s).

22. The method of any one of claims 19 to 21, wherein said comparing of the triboelectric signals in step (5) is carried out by using pattern recognition, machine learning and / or artificial intelligence (Al) techniques.

23. The method of any one of claims 19 to 22, wherein the test material is an organic material, textile, metal, inorganic material or a mixture thereof, and can have different forms, such as pellet or granulate, flake, powder, film or foil, thin top coat, fabric, threads, and / or wherein the test material has different surfaces, such as different surface finishes, e.g. e.g. rough, spikey, smooth.

24. The method of claim 23, wherein the test material is waste and the method further comprises the step(6) sorting the material.

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