GB2582627A

GB2582627A - Triboelectric generator

Info

Publication number: GB2582627A
Application number: GB1904345.4A
Authority: GB
Inventors: Pillow Jonathan; Venugopalan Vijay
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2019-03-28
Filing date: 2019-03-28
Publication date: 2020-09-30
Also published as: GB201904345D0

Abstract

A triboelectric generator includes at least two different triboelectric materials(TM) 7, 2 having contact surfaces 9, 4 that become charged, with a first conductor 10 mechanically and electrically connected to first TM 7, preferably opposite its contact surface 9, and a second conductor 6 arranged close to the contact surface 4 of the second TM. The conductors 10, 6 are coupled together and comprise the generator output circuit 13. The generator operates to generate opposite charge on the two TM, preferably from friction by sliding. At least the second TM surface 4 and conductor 6 are then moved to be proximate or to engage together so that the TM charge generates a displacement current in conductor 6. The charge at 9 is reflected in conductor 10. A third conductor 5 is preferably connected opposite to the contact surface 4. The extra conductor may enclose the triboelectric charges on the triboelectric surface to generate increased current within the external circuit. Many variations are shown in the figures, many with a further extra conductor (eg 20 in figure 4) operating similarly with surface 9. The variations (figures 5-9) show different ways of arranging the motion of the extra conductors towards and away from the TM surfaces along with the motion of the TM surfaces themselves, preferably in a cyclic manner. Several generator units may be connected in parallel (figures 10-13)

Description

TRIBOELECTRIC GENERATOR

BACKGROUND

Embodiments of the present disclosure, relate to triboelectric generators, and more particularly, but not by way of limitation, to triboelectric nanogenerators (TENGs).

Triboelectric devices convert mechanical energy into electrical energy using the triboelectric effect. These devices have a variety of potential applications, for example as energy-harvesting devices with respect to human motion, and mechanical sensors for touch pads.

In general, a drawback of triboelectric generators is their low power output. Typically, triboelectric generators provide high-voltage and low current outputs. Much research within the field of triboelectric devices is focussed on increasing current output for a given voltage.

A solution to increasing the current output of triboelectric generators consists of increasing the triboelectric charge density between two tribo-active layers within the triboelectric generator. Typically, this is done by improving contact between the tribo-active layers, changing the morphology and/or stability of the tribo-active layers, and/or increasing the inherent charge density of the layers. Additionally, efforts have been made to optimize device impedance matching.

SUMMARY

In some embodiments there is provided a triboelectric generator. The triboelectric generator includes a first section including a first conducting layer and a first triboelectric layer formed of a first triboelectric material, wherein the first triboelectric material includes a first active surface. The triboelectric generator also includes a second section including a second forward section and a second trailing section, wherein the second forward section includes a second triboelectric layer formed of a second triboelectric material and the second trailing section includes a second conducting layer, and wherein the second triboelectric layer includes a second active surface. The triboelectric generator also includes an electrical coupler electrically coupling the second conducting layer with the first conducting layer. The second section is configured in use to move with respect to the first section to provide that the first active surface and the second active surface frictionally engage to generate a first electrical charge in the first triboelectric layer and a second electrical charge in the second triboelectric layer, and to provide that the second conducting layer comes into engagement with, or into proximity to, the first triboelectric layer to generate a displacement current in the second conducting layer of the second trailing section.

The triboelectric generator may include the second forward section including a third conducting layer, and an electrical coupler jointly electrically coupling the second conducting layer and the first conducting layer with the third conducting layer, such that the displacement current is arranged to flow between the second conducting layer and the io first conducting layer and the third conducting layer.

The triboelectric generator may include a fourth conducting layer included in the first or second section, an electrical coupler jointly electrically coupling the third conducting layer and the fourth conducting layer with the second conducting layer and the first conducting layer, the third conducting layer and the fourth conducting layer being jointly electrically coupled. The second section is configured in use to move with respect to the first section to provide that the fourth conducting layer comes into engagement with, or into proximity to, the second triboelectric layer to generate a displacement current in the fourth conducting layer.

The triboelectric generator may include the second trailing second including the fourth conducting layer, wherein the second trailing section is configured in use to move with respect to the second forward section as the second section moves with respect to the first section.

The triboelectric generator may include the second section including a fourth conducting layer, the first section including a third conducting layer and a third triboelectric layer formed of the first triboelectric material, wherein the third triboelectric material incldues a third active surface. The triboelectric generator may also include an electrical coupler jointly electrically coupling the second conducting layer and the first conducting layer with the third conducting layer and the fourth conducting layer, the third conducting layer and the fourth conducting layer being jointly electrically coupled. The second section is configured in use to move with respect to the first section to provide that the second active surface and the third active surface frictionally engage to generate the first electrical charge in the third triboelectric layer and the second electrical charge in the second triboelectric layer, and to provide that the fourth conducting layer comes into engagement with, or into proximity to, the third triboelectric layer to generate a displacement current in the fourth conducting layer.

The triboelectric generator may include the first section including a fifth conducting layer and a fifth triboelectric layer formed of the first triboelectric material, wherein the fifth triboelectric material includes a fifth active surface. The triboelectric generator may also include an electrical coupler jointly electrically coupling the second conducting layer and the first conducting layer with the fifth conducting layer. The second section is configured in use to move with respect to the first section to provide that the second active surface and is the fifth active surface frictionally engage to generate the first electrical charge in the fifth triboelectric layer and the second electrical charge in the second triboelectric layer, and to provide the second conducting layer comes into engagement with, or into proximity to, the fifth triboelectric layer to generate a displacement current in the second conducting layer.

The triboelectric material may be aluminium, polytetrafluoroethylene, or nitrile rubber.

The second conducting layer and/or fourth conducting layer may include a conductor having a conductor surface.

The conductor may be aluminium or indium tin oxide. The second conducting layer and/or the fourth conducting layer may include a dielectric layer having a dielectric surface.

The dielectric may be polytetrafluoroethylene. The second conducting layer and/or the fourth conducting layer may include at least one spacer element provided on a part of the 25 conductor surface.

The second conducting layer and/or the fourth conducting layer may include at least one spacer element provided on a part of the dielectric surface. The spacer element may be a triboelectric material.

A system may include the triboelectric generator and a load arranged to connect to the triboelectric generator, wherein the system is configured to drive a current through the load in response to generation of contact electrification charges in the generator.

The triboelectric generator includes a first section including a first conducting layer, a first triboelectric layer formed of a first triboelectric material, and a fourth conducting layer, wherein the first triboelectric material includes a first active surface. The triboelectric generator also includes a second section including a second forward section and a second trailing section, wherein the second forward section includes a second triboelectric layer formed of a second triboelectric material and a third conducting layer, and the second trailing section includes a second conducting layer, and wherein the second triboelectric layer includes a second active surface. The triboelectric generator also includes an electrical coupler jointly electrically coupling the third conducting layer and the fourth conducting layer with the second conducting layer and the first conducting layer, the third conducting layer and the fourth conducting layer being jointly electrically coupled, and the second conducting layer and the first conducting layer being jointly electrically coupled.

The second section is configured in use to move with respect to the first section to provide that the first active surface and the second active surface frictionally engage to generate a first electrical charge in the first triboelectric layer and a second electrical charge in the second triboelectric layer, and to provide that the second conducting layer comes into engagement with, or into proximity to, the first triboelectric layer to generate a displacement current in the second conducting layer of the second trailing section, and to provide that the fourth conducting layer comes into engagement with, or into proximity to, the second triboelectric layer to generate a displacement current in the fourth conducting layer.

DESCRIPTION OF THE DRAWINGS

The disclosed technology and accompanying figures describe some implementations of the disclosed technology.

Figure 1 schematically illustrates a first triboelectric device; Figure 2 schematically illustrates a functioning of the first triboelectric device; Figures 3a to 3d schematically illustrate a conducting layer; Figure 4 schematically illustrates a second triboelectric device; Figure 5 schematically illustrates a functioning of the second triboelectric device; Figure 6 schematically illustrates a third triboelectric device; Figure 7 schematically illustrates a functioning of the third triboelectric device; Figure 8 schematically illustrates a fourth triboelectric device; Figure 9 schematically illustrates a functioning of the fourth triboelectric device; Figure to schematically illustrates a fifth triboelectric device; Figure na schematically illustrates a first view of fourth and fifth regions of the fifth triboelectric device; Figure nb schematically illustrates a second view of fourth and fifth regions of the fifth triboelectric device; Figure 12a schematically illustrates a first view of a sixth region of the fifth triboelectric device; Figure 12b schematically illustrates a second view of the sixth region of the fifth triboelectric device; Figure 13 schematically illustrates a functioning of the fifth triboelectric device; Figure 14 shows a first data plot; Figure 15 shows a second data plot; Figure 16 shows a third data plot; Figure 17 shows a fourth data plot; and Figure 18 schematically illustrates a triboelectric system.

The drawings are not drawn to scale and have various viewpoints and perspectives. The drawings are some implementations and examples. Additionally, some components and/or operations may be separated into different blocks or combined into a single block for the purposes of discussion of some of the embodiments of the disclosed technology. Moreover, while the technology is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the technology to the particular implementations described. On the contrary, the technology is intended to cover all modifications, equivalents, and alternatives falling within the scope of the technology as defined by the appended claims.

DETAILED DESCRIPTION

Unless the context clearly requires otherwise, throughout the description and the claims, 3o the words "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." As used herein, the terms "connected," "coupled," or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, electromagnetic, or a combination thereof. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or," in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. As used herein, by a material "over" a layer is meant that the material is in direct contact with the layer or is spaced apart therefrom by one or more intervening layers. As used herein, by a material "on" a layer is meant that the material is in direct contact with that layer. A layer "between" two other layers as described herein may be in direct contact with each of the two layers it is between or may be spaced apart from one or both of the two other layers by one or more intervening layers.

The teachings of the technology provided herein can be applied to other systems, not necessarily the system described below. The elements and acts of the various examples described below can be combined to provide further implementations of the technology. Some alternative implementations of the technology may include not only additional elements to those implementations noted below, but also may include fewer elements.

These and other changes can be made to the technology in light of the following detailed description. While the description describes certain examples of the technology, and describes the best mode contemplated, no matter how detailed the description appears, the technology can be practiced in many ways. Details of the system may vary considerably in its specific implementation, while still being encompassed by the technology disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the technology should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific examples disclosed in the specification, unless the Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the technology encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the technology under the claims.

To reduce the number of claims, certain aspects of the technology are presented below in certain claim forms, but the applicant contemplates the various aspects of the technology in any number of claim forms. For example, while some aspect of the technology may be recited as a computer-readable medium claim, other aspects may likewise be embodied as a computer-readable medium claim, or in other forms, such as being embodied in a meansplus-function claim.

In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of implementations of the disclosed 10 technology. It will be apparent, however, to one skilled in the art that embodiments of the disclosed technology may be practiced without some of these specific details.

The techniques introduced here can be embodied as special-purpose hardware (e.g., circuitry), as programmable circuitry appropriately programmed with software and/or firmware, or as a combination of special-purpose and programmable circuitry. Hence, embodiments may include a machine-readable medium having stored thereon instructions which may be used to program a computer (or other electronic devices) to perform a process. The machine-readable medium may include, but is not limited to, floppy diskettes, optical disks, compact disc read-only memories (CD-ROMs), magneto-optical disks, ROMs, random access memories (RAMs), erasable programmable read-only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs), magnetic or optical cards, flash memory, or other type of media / machine-readable medium suitable for storing electronic instructions. The machine-readable medium includes non-transitory medium, where non-transitory excludes propagation signals. For example, a processor can be connected to a non-transitory computer-readable medium that stores instructions for executing instructions by the processor.

First triboelectric device 1 Figure 1 is a schematic illustration of a device according to some embodiments of the

present disclosure.

Referring to Figure 1, a first triboelectric device 1 is shown.

The first triboelectric device 1 includes a first region 2, for example in the form of a film or a block, formed of a first triboelectric material ("first triboelectric layer") and having first and second surfaces 3, 4, preferably opposite surfaces. The device 1 also includes a first conducting layer 5, which is provided on the first surface 3. A first section may include the first conducting layer 5 and the first region 2. The device 1 also includes a second conducting layer 6 electrically connected to the first conducting layer 5. The second conducting layer 6 may be in contact with the first region 2. The second conducting layer 6 may be arranged sufficiently dose to the second surface 4 of the first region 2, as will be explained in greater detail hereinafter.

The first region 2 may extend across a direction along the x axis and a direction along the y axis i.e. in the x-y plane. Thus at least one of the first and second surfaces 3, 4 may extend across the x-y plane. At least one of the first and second surfaces 3, 4 may have a surface area of between 1 pm-and 4 m2 for example. The second conducting layer 6 may be separated from the second surface 4 of the first region 2 by a distance S in a direction substantially normal to the second surface 4 (preferably, in a direction along the z axis). The distance S may be no more than lo% of a length 1 of the second surface 4 (length 1 lies /5 along the x axis in Figure 1). The second conducting layer 6 may be in contact with the second surface 4, as will be explained in more detail hereinafter.

The first region 2 may have thickness t, extending in the z direction, which may be parallel to a direction normal to the plane of at least one of the first and second surfaces 3, 4. The 20 first region 2 may have thickness t, of between 1 gm and 4 mm.

The first conducting layer 5 may be directly or indirectly provided on the first surface 3. There may be at least one intermediate layer (not shown) between the first conducting layer 5 and the first surface 3. The at least one intermediate layer (not shown) may be formed of a ferroelectric liquid or a magnetization film or a combination of different materials for example.

The first triboelectric device 1 also includes a second region 7 ("second triboelectric layer") having third and fourth surfaces 8, 9, preferably opposite surfaces. The second region 7 is similar to the first region 2. However the second region 7 is formed of a second, different triboelectric material. The first triboelectric device 1 may also include a third conducting layer lo provided on the third surface 8. The third conducting layer 10 is similar to the first conducting layer 5.The first and third conducting layers 5, 10 may be formed of any suitable conductive material.

A second section includes a second trailing section and a second forward section. The second trailing section may include the second conducting layer 6. The second forward section may include the second region 7 and, optionally, the third conducting layer 10.

The second surface 4 faces the fourth surface 9. The direction normal to the plane of the second surface 4 may be substantially parallel to the direct normal to the plane of the fourth surface 9 (the planes are shown to lie along the x-axis). The first and second regions 2, 7 may be provided between the first conducting layer 5 and the third conducting layer 10.

The first conducting layer 5 and the second conducting layer 6 may be jointly electrically connected to the third conducting layer 10 (the joint electrical connection between the first and second conducting layers 5, 6 and the third conducting layer 10 is not shown in Figure 1). Alternatively, the first conducting layer 5 and the second conducting layer 6 may be jointly electrically connected to ground (not shown).

A load (not shown) may be electrically connected to the first triboelectric device 1 such that the device 1 powers the load. Specifically, the load (not shown) may be electrically connected between the first and second conducting layers 5, 6 and the third conducting layer 10. Alternatively, the load (not shown) may be electrically connected between the first and second conducting layers 5, 6 and ground. In an example where the load (not shown) is electrically connected between the first and second conducting layers 5, 6 and ground, the third conducting layer lo may not be present. The third conducting layer lo is present when the load (not shown) is connected between the first and second conducting layers 5, 6 and the third conducting layer 10.

The first region 2 (and second region 7) is formed of triboelectric material; examples of triboelectric materials include aluminium, polytetrafluoroethylene (Teflon RTM), nitrile rubber, and other tribo-active materials.

An electrical coupler may provide an electrical connection between conducting layers 5, 6, 10, or other conducting layers described herein, where necessary.

Referring to Figures 1 and 2, the operation of the first triboelectric device 1 will now be briefly described.

Certain materials may exchange electrons when brought into contact, such that the contact surfaces of each material become charged. This contact electrification is due to the triboelectric effect. Thus, triboelectric charges 11 may be generated on surfaces of triboelectric material included in the first triboelectric device 1.

For example, first triboelectric charges n,, n ("contact electrification charges") are generated on the fourth surface 9 ("second active surface") and second, oppositely charged triboelectric charges 112, 11 are generated on the second surface 4 ("first active surface") when the second region 7 and the first region 2 are brought into contact such that the fourth surface 9 and the second surface 4 are frictionally engaged (Si, also known as Stage 1, in Figure 2). For example, the second region 7 may move relative to the first region 2 so that the second and fourth surfaces 4, 9, become frictionally engaged. The first triboelectric charges 11, may be negative and the second triboelectric charges ih may be positive.

/5 The triboelectric charges ii give rise to an electric field 12. The strength of the electric field 12 changes when the relative positions of the second surface 4 and the fourth surface 9 change (S2 in Figure 2). The second region 7 may move with respect to the first region 2 so that the fourth surface 9 moves with respect to the second surface 4. The fourth surface 9 may move laterally ("lateral direction L") with respect to the second surface 4 (the lateral direction L is shown to lie along the x axis in Figure 2).

The second conducting layer 6 moves concurrently with the second region 7. The second conducting layer 6 moves so that the conducting layer 6 is brought into contact with, or sufficiently close to, the first region 2 such that the second conducting layer 6 couples to the electric field 12 generated by the triboelectric charges 11 at the second surface 4. The first conducting layer 5 is in contact with the first region 2 for coupling to the electric field 12 generated by the triboelectric charges 11 at the second surface 4. The third conducting layer 10 (if present) is in contact with the second region 7 for coupling to the electric field 12 generated by the triboelectric charges ii at the fourth surface 9.

When the electric field strength changes, the electric field 12 generates a potential difference. As the second and first conducting layers 5, 6 are arranged to couple to the electric field, the potential difference induces a displacement current C to flow in the first and second conducting layers 5, 6 (S2 in Figure 2). The first and second conducting layers 5, 6 are shorted electrically. When the third conducting layer 10 is included in the first triboelectric device 1 (as shown in Figure 2), the displacement current C may also flow in the third conducting layer 10.

The displacement current C may flow between the first and second conducting layers 5, 6 and the third conducting layer 10. For example, the displacement current C may flow from the first and second conducting layers 5, 6 to the third conducting layer 10 (S2 in Figure 2). If the load 13 is electrically connected between the first and second conducting layers 5, 6 and the third conducting layer 10, the displacement current C flows through the load 13.

As hereinbefore described, as an alternative the first conducting layer 5 and the second conducting layer 6 may be jointly electrically connected to ground (not shown) such that the displacement current C runs from the first and second conducting layers 5, 6 to ground. If the load 13 is electrically connected between the first and second conducting layers 5, 6 and ground, the displacement current C may run through it. The first triboelectric device 1 powers the load 13 when the displacement current C runs through it.

As the displacement current C flows (S2 in Figure 2), there is a gradual build-up of displacement charges 14 on the first, second, and, if present, third conducting layers 5, 6, 10. The displacement charges 14 on the first and second conducting layers 5, 6 are of an opposite charge to the displacement charges 14 on the third conducting layer 10.

As a result of the relative movement between the second and fourth surfaces 4, 9, these surfaces 4, 9 may become completely separated. Thus, no further triboelectric charges n are generated. The displacement charges 14 have the effect of compensating for or cancelling the generation of triboelectric charges 11 on each of the separated second and fourth surfaces 4, 9. The displacement current C ceases to flow when a sufficient amount of displacement charges 14 have built up on the conducting layers 5, 6, ao so as to cancel out the effect of the triboelectric charges 11 (S3 in Figure 2).

In typical triboelectric devices, a single conducting layer only is arranged in contact or close to the tribo-active surface for coupling to the changing electric field. As electric fields are produced in 4Th directions, a limited section of the field will intersect the single conducting layer. As such, the changing electric field arising from the triboelectric charges is not completely harnessed in a typical triboelectric device.

The second conducting layer 6 may help to partially, or even completely, enclose the triboelectric charges 11. A greater section of the electric field 12 compared to the electric field in a typical triboelectric device intersects the conducting layers 5, 6 (see, for example, S2 of Figure 2). Thus, a greater section of the electric field 12 may be harnessed for displacement current generation compared to a typical triboelectric device. This has the effect of improving the current output of the first triboelectric device 1 compared to a typical triboelectric device for a given voltage.

Referring to Figures 3a to 3d, different example structures 15 of the second conducting layer 6 will now be described in more detail.

A first structure 15, 15, of the second conducting layer 6 (Figure 1) may consist of a conductor 16. The conductor 16 may be formed of any suitable conducting material or combination of conducting materials, for example aluminium or indium tin oxide. Other /5 examples of suitable conducting materials include metals, doped oxides, carbon nanotubes, carbon paste, conducting polymers, and 2D conductors.

A second structure 15,15, of the second conducting layer 6 may consist of the conductor 16 and a dielectric 17 in contact with the conductor 16. The dielectric 17 may be, for example, polytetrafluoroethylene (i.e., Teflon (RTM)). The second conducting layer 6 may be positioned relative to the first region 2 such that the dielectric 17 is situated in between the conductor 16 and the first region 2.

The second conducting layer 6 may include an at least one spacer element 18. A third structure 15, 153 may consist of the conductor 16 and at least one spacer element 18 provided on a part of a conductor surface 16,, of the conductor 16. Alternatively, a fourth structure 15, 154 may consist of the conductor 16, the dielectric 17 in contact with the conductor 16, and the at least one spacer element 18 provided on a part of a dielectric surface 170 of the dielectric 17, such that the dielectric 17 is provided between the conductor 16 and the at least one spacer element 18.

The second conducting layer 6 may be positioned relative to the first region 2 such that the at least one spacer element 18 is situated in between the conductor 16 (and, if present, the dielectric 17) and the first region 2.

The at least one spacer element 18 is preferably formed of the second triboelectric material (which the second region 7 is formed from), or preferably a material with similar triboelectric properties to the second triboelectric material. The at least one spacer 18 may be formed of other suitable material.

The at least one spacer element 18 may be a discrete piece of suitable triboelectric material. Two spacer elements 18 may be provided on the conductor 16 and spaced apart by a distance d (shown to lie along the x direction in Figure 3c). Three or more spacer elements 18 may be positioned along the conductor 16; the three or more spacer elements 18 may be uniformly or non-uniformly spaced apart in the direction of distance d.

Certain example structures 15 of the second conducting layer 6 may help to generate higher displacements currents. For example, the second conducting layer 6 having the second structure 15,, may help to prevent the transfer of triboelectric charges 11 (Figure 2) from the /5 second surface 4 if the conducting layer 6 is in contact with the first region 2 (Figure 1).

This is because the dielectric 17 acts a triboelectric charge barrier. This allows the conducting layer 6 to be placed in very close proximity to the first region 2 (Figure 1) such that coupling with the electric field 12 (Figure 2) is maximised.

Certain example structures 15 of the second conducting layer 6 which include the at least one spacer element 18 may give rise to a number of other advantageous effects. For example, the at least one spacer element 18 may provide, or at least enhance, spatial stability to the first triboelectric device 1. Furthermore, the spacer element 18 may provide separation, or at least partial separation, between the conductor 16 and the first region 2.

For example, when pressure is applied to the device 1, the second conducting layer 6 and the first region 2 may be made to contact. However, the spacer element 18 in this example may significantly reduce, or even prevent, direct contact between the conductor 16 and the first region 2. Consequently, friction and corrosion of the second surface 4 may be reduced. The operational stability of the first triboelectric device 1 may not be adversely affected by the inclusion of the second conducting layer 6.

The separation or at least partial separation between the conductor 16 and the first region 2 reduces, or even prevents, the possibility of shorting between the conductor 16 and the second surface 4. Thus, the inclusion of at least one spacer element 18 in the second conducting layer 6 may help to increase the power performance of the first triboelectric device 1. This is because shorting between the conductor 16 and the second surface 4 would reduce the density of the triboelectric charges 112 on the second surface 4, which would lead to a reduced power performance of the first triboelectric device 1.

The second conducting layer 6 may have thickness extending in the z direction of between 5 10 nm to 10 mm. The addition of the second conducting layer 6 within the triboelectric device 1 may be used in other arrangements of triboelectric devices.

Second triboelectric device 17 Figure 4 is a schematic illustration of a device according to some embodiments of the /a present disclosure. Referring to Figure 4, a second triboelectric device 19 is shown.

The second triboelectric device 19 is similar to the first triboelectric device 1 (Figure 1). Thus, the second triboelectric device 19 includes the first region 2 having the first surface 3 and the second surface 4, the first conducting layer 5 provided on the first surface 3, and /5 the second conducting layer 6 electrically connected to the first conducting layer 5. The second triboelectric device 19 also includes the second region 7 having the third and fourth surfaces 8, 9, as well as the third conducting layer 10 provided on the third surface 8.

The second triboelectric device 19 further includes a fourth conducting layer 20 which may be arranged sufficiently close to or in contact with the second region 7, as will be described in more detail hereinafter. The first section may include the fourth conducting layer 20, the first conducting layer 5 and the first region 2. The fourth conducting layer 20 is electrically connected to the third conducting layer 10. The third and fourth conducting layers 10, 20 are shorted electrically. The third and fourth conducting layers 10, 20 are jointly electrically connected to the first and second conducting layers 5, 6. When the second triboelectric device 19 is in operation, the displacement current flows between the third and fourth conducting layers 10, 20 and the first and second conducting layers 5, 6. This will be described in more detail hereinafter.

The fourth conducting layer 20 may have any one of the same example structures 15 (Figures 3a to 3d) as in the second conducting layer 6. The at least one spacer element 18 (Figures 3c and 3d) in the fourth conducting layer zo is preferably formed of the first triboelectric material (which the first region 2 is formed from), or preferably a material with similar triboelectric properties to the first triboelectric material. However, the spacer element 18 (Figures 3c and 3d) in the fourth conducting layer 20 may be formed of other suitable material. The power performance of an example of the device 1 (Figure I), 17 may be increased by having the spacer elements 18 in the second and fourth conducting layers 6, 20 be formed of the second and first triboelectric materials respectively.

Referring to Figures 4 and 5, operation of the second triboelectric device, 19 will now be described.

The second triboelectric device 19 operates in a similar way to the first triboelectric device 1 (Figure 1). When the first region 2 and the second region 7 are brought into contact such that the second and fourth surfaces 4, 9, frictionally engage, triboelectric charges 11 may be generated on the second and fourth surfaces 4, 9 of the first and second regions 2, 7 respectively. The second surface 4 may become positively charged and the fourth surface 9 may become negatively charged (Si in Figure 5). An electric field (not shown) arises due to the triboelectric charges 11.

/5 To change the strength of the electric field, the second surface 4 and the fourth surface 9 are moved relative to each other (in other words, the first and second regions 2, 7 are moved relative to each other). The fourth surface 9 may move relative to the second surface 4, for example in the lateral direction L (the direction of movement is shown to lie along the x-axis in Figure 5). The first conducting layer 5 is in contact with the first region 2, and so moves concurrently with the first region 2. Likewise, the third conducting layer 10 moves concurrently with the second region 7.

The second conducting layer 6 moves concurrently with the second region 7 as hereinbefore described. Thus, the second conducting layer 6 is arranged to gradually overlie the second surface 4 as the conducting layer 6 moves. In a similar way, the fourth conducting layer 20 moves concurrently with the first region 2 and is arranged to gradually overlie the fourth surface 9 as the layer 20 moves (S2 in Figure 5). The fourth conducting layer 20 moves so that it is arranged sufficiently close to or in contact with the second region 7 such that the fourth conducting layer 20 couples to the electric field (not shown) generated by the triboelectric charges 11 on the fourth surface 9.

As a result of the change in strength of the electric field, a displacement current C is generated in the conducting layers 5, 6, 10, 20 in a similar way as hereinbefore described in reference to the first triboelectric device 1 (Figure 2). For example, the displacement current C flows from the first and second conducting layers 5, 6 to the third and fourth conducting layers 10, 20.

The load 13 (Figure 2) may be connected between the first and second conducting layers 5, 6 and the third and fourth conducting layers 10, 20. Thus the displacement current C may flow through the load 13 such that the second triboelectric device 19 powers it.

A greater portion of the changing electric field is harness in the second triboelectric device 19 compared to a typical triboelectric device. As hereinbefore described, the second conducting layer 6 helps to partially, or even completely, enclose the triboelectric charges 11 on the second surface 4. Additionally, the fourth conducting layer 20 helps to partially, or even completely, enclose the triboelectric charges 11 on the fourth surface 9. Thus, a greater section of the electric field (not shown) is harnessed for displacement current generation in the second triboelectric device 19 compared to a typical triboelectric device. Thus, the displacement current C generable in the triboelectric device 19 is increased for a given voltage compared to a typical triboelectric device.

As the displacement current C flows, there is a gradual build-up of displacement charges 14 on the conducting layers 5, 6, 10, zo. Specifically, there is a build-up of negative charge on the second conducting layer 5 and a build-up of positive charge on the fourth conducting layer 20 due to the direction of the displacement current C. The relative movement between the first and second regions 2, 7 may be terminated when the second and fourth surfaces 4, 9, do not-partially or otherwise-overlie each other. The second and fourth conducting layers 6, 20 may completely overlie the second and fourth surfaces 4, 9 respectively.

As hereinbefore described, the displacement charges 14 have the effect of compensating/cancelling the generation of triboelectric charges it Thus, the displacement current C ceases to flow (S3 in Figure 5) when a sufficient amount of displacement charges 14 have built up on the conducting layers 5, 6, 10, 20.

Si to S3 constitute one cycle of the operation of the second triboelectric device 19.

A proceeding cycle is instigated (S4 in Figure 5) by the relative movement of the first and second regions 2, 7, in a similar way as described in Si. However, the relative movement is 35 in opposite direction D as compared to the relative movements in Si. Thus, the direction of displacement current C is reversed in this preceding cycle.

Third triboelectric device 21 Figure 6 is a schematic illustration of a device according to some embodiments of the present disclosure. Referring to Figure 6, a third triboelectric device 21 is shown.

The third triboelectric device 21 is very similar to the second triboelectric device 19 (Figure 4). However, the third triboelectric device includes a support structure 22 that is not present in the second triboelectric device 19 (Figure 4).

The support structure 22 may be connected separately to the second region 7 or the third conducting layer 10, or both the second region 7 and the third conducting layer 10. The support structure is connected to the second region 7 and/or third conducting layer 10 so that the support structure 22 moves concurrently with the second region 7 and/or third conducting layer 10. Alternatively, the support structure may be connected to the first /5 region 2, the first conducting layer 5, or both in a similar way. The support structure 22 is not electrically connected to any one of the regions 2, 7 or conducting layers 5, 10.

The support structure 22 is also separately connected to the second conducting layer 6 and the fourth conducting layer 20, such that the conducting layers 6, 20 are not in contact with each other. The support structure 22 does not electrically connect either the second conducting layer 6 or the fourth conducting layer 20. The support structure 22 is configured to change the position of the second and fourth conducting layers 6, 20 relative to the second and fourth surface 4, 9, as will be explained in more detail hereinafter. The second trailing section may include the second conducting layer 6 and the fourth conducting layer 20.

The support structure 22 may be formed of non-conducting, rigid material.

Referring to Figures 6 and 7, operation of the third triboelectric device 21 will now be 3o described.

The third triboelectric device 21 operates in a similar way to the second triboelectric device 19 (Figure 4; Si in Figure 5). When the first region 2 and the second region 7 are brought into contact such that the second and fourth surfaces 4, 9 frictionally engage, triboelectric charges ii may be generated on the second and fourth surfaces 4, 9 of the first and second regions 2, 7 respectively (Si in Figure 7).

To change the strength of the electric field, the first and second regions 2, 7 are moved apart from one another. At the same time, the second and fourth conducting layers 6, 20 are brought closer to the second and fourth surfaces 4, 9 so that the second and fourth conducting layers 6, 20 couple to the electric field as hereinbefore described. Preferably, the second and fourth conducting layers 6, 20 are arranged between the second and fourth surfaces 4, 9 (Sz in Figure 7).

The supporting structure 22 is responsible for the movement of the second and fourth conducting layers 6, 20 during 52. Preferably, the supporting structure 22 rotates in the direction R normal to the plane of the fourth surface 9 (along the z direction in Figure 7) to arrange the second and fourth conducting layers 6, zo between the second and fourth surfaces 4, 9.

/5 As a result of the change in strength of the electric field, the displacement current C is generated. This is because the conducting layers 5, 6, 10, zo couple to the electric field as hereinbefore described. The displacement current C flows from the first and second conducting layers 5, 6 to the third and fourth conducting layers to, 20, as seen in the second triboelectric device 19 (S2 in Figure 5). Furthermore, there is a gradual build-up of displacement charges 14 on the conducting layers 5, 6, 10, 20.

The load 13 (Figure 2) may be connected between the first and second conducting layers 5, 6 and the third and fourth conducting layers 10, 20. Thus the displacement current C may flow through the load 13 such that the third triboelectric device 21 powers it.

As hereinbefore described, the displacement charges 14 have the effect of compensating/cancelling the generation of triboelectric charges 11. Thus, the displacement current C ceases to flow (S3 in Figure 5) when a sufficient amount of displacement charges 14 have built up on the conducting layers 5, 6, 10, 20 (53 in Figure 7).

Once the displacement current C ceases to flow, the supporting structure rotates in the direction opposite to the direction R. Thus, the second and fourth conducting layers 6, zo are moved away from the second and fourth surfaces 4, 9 such that the second and fourth conducting layers 6, 20 are not coupled to the electric field (S4 in Figure 7).

Si to S4 constitute one cycle of the operation of the third triboelectric device 21.

A proceeding cycle may be instigated by bringing the first and second regions 2, 7 closer together.

Fourth triboelectric device 23 Figure 8 is a schematic illustration of a device according to some embodiments of the present disclosure. Referring to Figure 8, a fourth triboelectric device 23 is shown.

The fourth triboelectric device 23 is similar to the second triboelectric device 19. Thus, the fourth triboelectric device 23 includes the first region 2 having the first surface 3 and the second surface 4, the first conducting layer 5 provided on the first surface 3, and the second conducting layer 6 electrically connected to the first conducting layer 5. The fourth triboelectric device 23 further includes the second region 7 (which may be referred to as a "third triboelectric layer" in this example) having the third and fourth surfaces 8, 9, the /5 third conducting layer lo provided on the third surface 8, and the fourth conducting layer 20. The fourth conducting layer 20 is electrically connected to the third conducting layer 10. The first section may include the second region 7, the third conducting layer 10, and the first region 2 and the first conducting layer 5.

The second surface 4 and the fourth surface 9 lie substantially adjacent and along substantially parallel directions (surfaces 4, 9 lie along the x direction in Figure 8). In the fourth triboelectric device 23, the second region 7 is formed of the first triboelectric material.

The fourth triboelectric device 23 also includes a third region 24 having a fifth surface 25. The third region 24 is similar to the first and second regions 2, 7 and the third region 24 is formed of the second triboelectric material.

The fifth surface 25 of the third region 24 may be arranged to face the second surface 4 and/or fourth surface 9. The fifth surface 25 may move relative to the second and fourth surfaces 4, 9 or the second and fourth surfaces 4, 9 may move relative to the fifth surface 25. The third region 24 may move in the lateral direction L (shown to lie along the x-axis in Figure 8) such that the fifth surface 25 completely, partially, or does not overlie the second surface 4 and such that the fifth surface 25 completely, partially, or does not overlie the fourth surface 9.This will be explained in more detail hereinafter.

Referring to Figures 8 and 9, operation of the fourth triboelectric device 23 will now be described.

When the first region 2 and the third region 24 are brought into contact such that the second and fifth surfaces 4, 25 frictionally engage, triboelectric charges 11 may be generated on the second and fifth surfaces 4, 25 of the second and third regions 1, 24 respectively. The second surface 4 may become positively charged and the fifth surface 25 may become negatively charged (Si in Figure 9). An electric field (not shown) arises due to the triboelectric charges it.

To change the strength of the electric field, the first and third regions 2, 24 move relative to each other. For example, the third region 24 moves relative to the first region 2, for example in the lateral direction L (shown to lie along the x-axis in Figure 9).

/5 As a result of the relative movement, the fifth surface 25 begins to only partially overlie the second surface 4. As the fourth surface 9 lies adjacent to the second surface 4 as hereinbefore described, the fifth surface 25 begins to partially overlie the fourth surface 9. The third region 24 begins to contact the second region 7 such that the fourth and fifth surfaces 9, 25 frictionally engage. The triboelectric charges 11 are generated on the fourth surface 9 (which may be referred to as a "third active surface" in this example), which are of the same polarity as the triboelectric charges 11 generated on the second surface 4 in Si.

The second conducting layer 6 moves concurrently with the third region 24. Thus the second conducting layer 6 is arranged to gradually overlie the second surface 4. In a similar way, the fourth conducting layer 20 moves concurrently with the third region 25. Thus the fourth conducting layer 20 is arranged to gradually decrease the extent to which the fourth conducting layer 20 overlies the fourth surface 9 (S2 in Figure 9). This is similar to the functioning of the second triboelectric device 19 (Figure 4) during S2.

In a similar way as hereinbefore described in reference to the first triboelectric device 1 (Figure 2), the conducting layers 5, 6, to, zo are arranged so that they couple to the electric field. Thus, the displacement current C flows between the first and second conducting layers 5, 6 to the third and fourth conducting layers to, 20. For example the displacement current C flows from the first and second conducting layers 5, 6 to the third and fourth conducting layers 10, 20 (S2 in Figure 9). Thus, there is a gradual build-up of displacement charges 14 on the conducting layers 5, 6, 10, 20.

The load 13 (Figure 2) may be connected between the first and second conducting layers 5, 6 and the third and fourth conducting layers 10, 20. Thus the displacement current C may flow through the load 13 (Figure 2) such that the fourth triboelectric device 23 powers the load 13 (Figure 2).

As hereinbefore described, the displacement charges 14 have the effect of compensating/cancelling the generation of triboelectric charges 11. Thus, the displacement current C ceases to flow when a sufficient amount of displacement charges 14 have built up io on the conducting layers 5, 6, 10, 20 (S3 in Figure 9). At this stage, the fifth surface 25 may completely overlie the fourth surface 9.

Sr to S3 constitute one cycle of the operation of the fourth triboelectric device 23.

In a similar way to the functioning of the second triboelectric device 19, a proceeding cycle is instigated (S4 in Figure 9) by the relative movement of the regions 2, 7, 24 in the opposite direction as compared to the relative movements in Si. For example, the third region 24 may move in the lateral direction D (which is opposite to the lateral direction T,) as the first and second regions 2, 7 remain stationary. Thus, the direction of displacement current C is reversed in this preceding cycle.

Fifth triboelectric device 26 Figure to is a schematic illustration of a device according to some embodiments of the present disclosure. Referring to Figures ro to 12, a fifth triboelectric device 26 will now be 25 described.

The fifth triboelectric device 26 includes a fourth region 27 having sixth and seventh surfaces 28, 29 and a fifth region 3o having eighth and ninth surfaces 31, 32. The fourth region 27 is formed of the first triboelectric material and is similar to the first region 2. The 3o fifth region 3o ("fifth triboelectric layer") is also formed of the first triboelectric material.

The fourth and fifth regions region 27, 3o may extend across a direction along the x axis and a direction along the y axis i.e. in the x-y plane. Thus at least one of the sixth and seventh surfaces 28, 29 and at least one of the eighth and ninth surfaces 31, 32 may extend 35 in the x-y plane. The directions normal to the planes of the seventh surface 29 and the ninth surface 32 are substantially parallel (the direction normal to the planes lies along the z axis in Figure io).

The fourth region 27 includes at least one first finger region 33, preferably a plurality of first finger regions 33, connected to a first strip region 34. The first strip region 34 extends in the x direction and each first finger region 33 individually protrudes from the first strip region 34 in the y direction. Each first finger region 33 is spaced apart from the other first finger regions 33 in the x direction. Likewise, the fifth region 30 is includes at least one second finger region 35, preferably a plurality of second finger regions 35, connected to a io second strip region 36. The second strip region 36 extends in the x direction and each second finger region 35 individually protrudes from the second strip region 36 in the y direction. Each second finger region 35 is spaced apart from the other second finger regions 35 in the x direction. The fourth region 27 and the fifth region 3o form an interdigitated arrangement such that the first and second finger regions 33, 35 are interleaving.

Due to their interdigitated arrangement, each first finger region 33 lies substantially adjacent in the x direction to each second finger region 35 (see Figure jib, which shows the view taken along line AB in Figure na). The directions normal to the planes of the seventh surface 29 and the ninth surface 32 are substantially parallel (this direction lies along the z axis in Figure rib).

The fifth triboelectric device 26 further includes a fifth conducting layer 37 in contact with the sixth surface 28, and a sixth conducting layer 38 in contact with the eighth surface 31.

The fifth conducting layer 37 follows the layout of the fourth region 27 such that the fourth region 27 completely covers the fifth conducting layer 37. The sixth conducting layer 38 follows the layout of the fifth region 30 such that the fifth region 30 completely covers the sixth conducting layer 38. The fifth conducting layer 37 and the sixth conducting layer 38 are not contacting and are not shorted electrically.

The fifth triboelectric device 26 further includes a sixth region 39 having a tenth surface 4o. The sixth region 39 is formed of the second, different triboelectric material. The sixth region 39 may extend across a direction along the x axis and a direction along the y axis i.e. in the x-y plane. The sixth region 39 includes at least one grating segment region 41.

Preferably, the sixth region 39 includes a plurality of grating segment regions 41. The grating segment regions 41 may lie along the y direction and may be spaced apart in the x direction. Thus, grating holes 42 are formed between the grating segment regions 41. The grating segment regions 41 lie substantially adjacent to each other in the x direction (see Figure 12b, which shows the view taken along line EF in Figure 12a).

Referring to Figure 10, the tenth surface 4o faces both the seventh and ninth surfaces 29, 32. The direction normal to the plane of the tenth surface 4o is substantially parallel to the direction normal to the planes of the seventh surface 29 and the ninth surface 32.

The fourth, fifth and sixth regions 27, 3o, 39 have the same periodicity. In other words, the /a sixth region 39 may be arranged to overlie the fourth and fifth regions 27, 3o so that each grating segment region 41 overlies one of the finger regions 33, 35.

The fifth conducting layer 37 is electrically connected to the sixth conducting layer 38. For example, each section of the fifth conducting layer 37 underlying the first finger regions 33 /5 (Figure (la) is jointly electrically connected at a node G. Each section of the sixth conducting layer 38 underlying the second finger regions 35 is jointly electrically connected at a node H. Nodes G and H are electrically connected.

The fifth triboelectric device 26 further includes at least one seventh conducting layer 43.

Preferably, the fifth triboelectric device 26 includes a plurality of seventh conducting layers 43. Each seventh conducting layer 43 is arranged in between the grating segment regions 41 such that the seventh conducting layers 43 and grating segment regions 41 are interleaving. Each seventh conducting layer 43 may be arranged in or near the grating holes 42.

Each seventh conducting layer 43 is connected in series. The plurality of seventh conducting layers 43 may be jointly electrically connected to the sixth conducting layer 38 (for example at node H in Figure io). In this example, the plurality of seventh conducting layers 43 and the sixth conducting layer 38 are electrically shorted. Alternatively, the 3o plurality of seventh conducting layers 43 may be jointly electrically connected to the fifth conducting layer 37 (for example at node G in Figure (o). In this example, the plurality of seventh conducting layers 43 and the sixth conducting layer 38 are electrically shorted.

Each seventh conducting layer 43 is similar to the second and fourth conducting layers 6, 35 20 as hereinbefore described. For example, each seventh conducting layer 43 may have any one of the same example structures 15 (Figures 3a to 3d) as hereinbefore described.

The fifth and sixth conducting layers 37, 38 are similar to the first and third conducting layers 5, 10 as hereinbefore described. For example, the fifth and sixth conducting layers 37, 38 may be formed of the same material.

Referring to Figures io to 13, operation of the fifth triboelectric device 26 will now be described.

The fifth triboelectric device 26 functions in a similar way to the fourth triboelectric device 23. As hereinbefore described, the sixth region 39 may be arranged to overlie, for example, the fifth region 30. Thus, the tenth surface 40 and the ninth surface 32 are brought into contact such that the ninth and tenth surface 32, 4o frictionally engage. As a result, triboelectric charges 11 are generated on the ninth and tenth surfaces 32, 4o (Si in Figure 13). The triboelectric charges 11 on the ninth surface 32 ("fifth active surface") have an /5 opposite polarity to the triboelectric charges 11 on the tenth surface 40. An electric field (not shown) arises due to the triboelectric charges ii.

The sixth region 39 moves relative to the fourth and fifth regions 27, 3o or the fourth and fifth regions 27, 3o move relative to the sixth region 39. For example, the sixth region may move in a lateral direction L (shown to lie along the x axis in Figure 13) relative to the fourth and fifth regions 27, 30.

As a result of the relative movement, the sixth region 39 begins to partially overlie the fourth region 27 rather than the fifth region 3o. Thus, the sixth region 39 begins to contact the fourth region 27 such that the tenth surface 40 and the seventh surface 29 frictionally engage. As a result, triboelectric charges 11 are generated on the seventh surface 29, which are of the same polarity as the triboelectric charges 12 on the ninth surface 32.

Each seventh conducting layer 43 moves concurrently with the sixth region 39 in the same direction. Thus, each seventh conducting layer 43 moves to gradually decrease the extent to which it overlies one of the finger regions 33, 35, for example one of the first finger regions 33, and moves to gradually increase the extent to which it overlies a different finger region 33, 35, for example one of the second finger regions 35. Each seventh conducting layer 43 is moved so that each seventh conducting layer 43 is sufficiently close to or contacting at least one of the seventh or ninth surfaces 29, 32 so as to couple to the electric

field (not shown).

As hereinbefore described, the relative movement changes the strength of the electric field-which generates a potential difference. The potential difference across at least the fifth, sixth, and seventh conducting layers 37, 38, 43, induces the displacement current C. In this example, the displacement current C flows between the fifth conducting layer 37 and the sixth and seventh conducting layer 38, 43 (S2 in Figure 13).

The load 13 may be connected between nodes G and H. Thus the displacement current C may flow through the load 13 such that the fifth triboelectric device 26 powers the load 13.

As hereinbefore described, the displacement charges 14 have the effect of compensating/cancelling the generation of triboelectric charges 11. Thus, the displacement current C ceases to flow (not shown) when a sufficient amount of displacement charges 14 have built up on the conducting layers 37, 38, 43.

In a similar way to the fourth triboelectric structure 23 (Figure 9), the displacement current C in the fifth triboelectric device 26 may be instigated again by reversing the movement direction (not shown) of the sixth region 39 relative to the fourth and fifth regions 27,30.

Experimental Results Experimental results further illustrate how the addition of at least one of the second, fourth, or seventh conducting layers 6 (Figure 2), 20 (Figure 5), 43 (Figure 13) produces an increase in the displacement current of the triboelectric device 1, 19, 21, 23, 26 (Figure 1; Figure 4; Figure 6; Figure 8; Figure lo) compared to a typical triboelectric device for a given voltage.

Figure 14 shows a first data plot 44, 44, of measured current values over time for a triboelectric device. The data plots between o seconds and 3o seconds correspond to measurements taken of the typical triboelectric device in operation. The data plots taken between 3o seconds and 52 seconds correspond to measurements taken of the first triboelectric device 1 (Figure 2) in operation.

The first data plot 44, shows an approximate increase of factor 2 in the displacement current over one cycle of the device 1, as compared to a typical triboelectric device.

Referring to Figures 2, 3b, and 14, the first triboelectric device 1 used to collect the results shown in the first data plot 44, includes the second conducting layer 6 having the second structure 15, 152. The conductor 16 is aluminium and the dielectric 17 is Teflon.

The first region 2 is formed of Teflon and the second region 7 is formed of aluminium. The dielectric 17 included in the second conducting layer 6 may help to completely remove, or at least reduce, the possibility that the triboelectric charges 11 are discharged by the conductor 16. Furthermore, the second conducting layer 6 and the second surface 4 do not generate additional triboelectric charges 11 on contact, as the dielectric 17 and the first region 2 are both formed of Teflon. Therefore, frictional engagement between the dielectric 17 and the second surface 4 does not induce any additional displacement current C. Figure 15 shows a second data plot 44, 442 of measured current values over time for a triboelectric device. The data plots between o seconds and 27 seconds correspond to measurements taken of the typical triboelectric device in operation. The data plots taken between 27 seconds and 54 seconds correspond to measurements taken of the first triboelectric device 1 (Figure 2) in operation.

Referring to Figures 2, 3a, and 15, the first triboelectric device 1 used to collect the results shown in the second data plot 442 includes the second conducting layer 6 having the first structure 15, 15,. The conductor 16 is aluminium. The first region 2 is formed of Teflon and the second region 7 is formed of aluminium. The second data plot 44, shows an approximate increase in the displacement current of factor 2 over one cycle of the device 1, as compared to the typical triboelectric device.

Thus, use of a conductor 16 only in the conducting layer 6 is also shown to increase current in the triboelectric device 1. In this example of the first triboelectric device 1 used to collect the results, there is no discharge of triboelectric charges 11 from the second surface 4 to the conducting layer 6.

Figure 16 shows a third data plot 44, 443 of measured current values over time for a triboelectric device. The data plots between o seconds and 100 seconds correspond to measurements taken of the typical triboelectric device. The data plots taken between 100 seconds and 210 seconds correspond to measurements taken of the first triboelectric device 1 (Figure 2).

Referring to Figures 2 and 16, the first triboelectric device 1 used in relation to the results in the third data plot 443 is the same as the device 1 used in relation to the results shown in the second data plot 442 (Figure 15). However, the conducting layer 6 is formed of indium tin oxide, rather than aluminium. The third data plot 443 shows an approximate increase in the displacement current of factor 2 over one cycle of the device 1, as compared to the typical triboelectric device.

Figure 17 shows a fourth data plot 44, 444 of measured current values over time for a triboelectric device. The data plots between o seconds and 15 seconds correspond to measurements taken of the typical triboelectric device. The data plots taken between 15 seconds and 27 seconds correspond to measurements taken of the first triboelectric device 1 (Figure 2).

Referring to Figures 2 and 17, the first triboelectric device 1 used in relation to the results /5 in the fourth data plot 444 is the same as device 1 used in relation to the results shown in the second data plot 44.2 (Figure 15). However, the first region 2 is formed of nitrile rubber and the second region 7 is formed of Teflon. The fourth data plot 444 shows an approximate increase in the displacement current of factor 2 over one cycle of the device 1, as compared to a typical triboelectric device.

Triboelectric system 45 Referring to Figure 18, a triboelectric system 45 will now be described.

The triboelectric system 45 includes the triboelectric device 1; 19; 21; 23; 26 and the load 13. The load 13 is electrically connected to the triboelectric device 1; 19; 21; 23; 26. As hereinbefore described, the load 13 is connect in such a way that when the device 1; 19; 21; 23; 26 is in operation, the displacement current C (see, for example, Figure 5) may be driven through the load 13 to power the load 13.

Claims

Claims 1. A triboelectric generator, comprising: a first section comprising a first conducting layer and a first triboelectric layer formed of a first triboelectric material, wherein the first triboelectric material comprises a first active surface; a second section comprising a second forward section and a second trailing section, wherein the second forward section comprises a second triboelectric layer formed of a second triboelectric material and the second trailing section comprises a second conducting layer, and wherein the second triboelectric layer comprises a second active surface; and an electrical coupler electrically coupling the second conducting layer with the first conducting layer, wherein: the second section is configured in use to move with respect to the first section to provide that the first active surface and the second active surface frictionally engage to generate a first electrical charge in the first triboelectric layer and a second electrical charge in the second triboelectric layer, and to provide that the second conducting layer comes into engagement with, or into proximity to, the first triboelectric layer to generate a displacement current in the second conducting layer of the second trailing section.
2. The triboelectric generator of claim 1, the generator comprising: the second forward section comprising a third conducting layer; an electrical coupler jointly electrically coupling the second conducting layer and the first conducting layer with the third conducting layer, such that the displacement current is arranged to flow between the second conducting layer and the first conducting 25 layer and the third conducting layer.
3. The triboelectric generator of claim 2, the generator comprising: a fourth conducting layer comprised in the first or second section; an electrical coupler jointly electrically coupling the third conducting layer and the fourth conducting layer with the second conducting layer and the first conducting layer, the third conducting layer and the fourth conducting layer being jointly electrically coupled, wherein: the second section is configured in use to move with respect to the first section to provide that the fourth conducting layer comes into engagement with, or into proximity to, the second triboelectric layer to generate a displacement current in the fourth conducting layer.
4 The triboelectric generator of claim 3, wherein the second trailing second comprises the fourth conducting layer, wherein: the second trailing section is configured in use to move with respect to the second forward section as the second section moves with respect to the first section.
5. The triboelectric generator of claim 1, the triboelectric generator comprising: the second section comprising a fourth conducting layer; the first section comprising a third conducting layer and a third triboelectric layer formed of the first triboelectric material, wherein the third triboelectric material comprises a third active surface; an electrical coupler jointly electrically coupling the second conducting layer and the first conducting layer with the third conducting layer and the fourth conducting layer, the third conducting layer and the fourth conducting layer being jointly electrically coupled, wherein: the second section is configured in use to move with respect to the first section to provide that the second active surface and the third active surface frictionally engage to generate the first electrical charge in the third triboelectric layer and the second electrical charge in the second triboelectric layer, and to provide that the fourth conducting layer comes into engagement with, or into proximity to, the third triboelectric layer to generate a displacement current in the fourth conducting layer.
6. The triboelectric generator of claim 1, the triboelectric generator comprising: the first section comprising a fifth conducting layer and a fifth triboelectric layer formed of the first triboelectric material, wherein the fifth triboelectric material comprises a fifth active surface; an electrical coupler jointly electrically coupling the second conducting layer and the first conducting layer with the fifth conducting layer, wherein: the second section is configured in use to move with respect to the first section to provide that the second active surface and the fifth active surface frictionally engage to generate the first electrical charge in the fifth triboelectric layer and the second electrical charge in the second triboelectric layer, and to provide the second conducting layer comes into engagement with, or into proximity to, the fifth triboelectric layer to generate a displacement current in the second conducting layer.
7. The triboelectric generator of any one of claims i to 6, wherein the triboelectric material is aluminium, polytetrafluoroethylene, or nitrile rubber.
8. The triboelectric generator of any one of claims 1 to 7, wherein the second 15 conducting layer and/or fourth conducting layer comprises a conductor having a conductor surface.
9. The triboelectric generator of claim 8, wherein the conductor is aluminium or indium tin oxide.
10. The triboelectric generator of claim 8 or 9, wherein the second conducting layer and/or the fourth conducting layer comprises a dielectric layer having a dielectric surface.it.
The triboelectric generator of claim 10, wherein the dielectric is polytetrafluoroethylene.
12. The triboelectric generator of any one of claims 8 or 9, wherein the 25 second conducting layer and/or the fourth conducting layer comprises at least one spacer element provided on a part of the conductor surface.
13. The triboelectric generator of any one of claims 10 or 11, wherein the second conducting layer and/or the fourth conducting layer comprises at least one spacer element provided on a part of the dielectric surface.
14. The triboelectric generator of any one of claims 12 or 13, wherein the spacer element is a triboelectric material.
15. A system comprising: the triboelectric generator of any one of claims 1 to 14; and a load arranged to connect to the triboelectric generator; wherein the system is configured to drive a current through the load in response to generation of contact electrification charges in the generator.