FIELD OF INVENTION

This invention relates to an energy harvesting wearable device.

BACKGROUND

Energy harvesting wearable devices are generally known and typically include either a piezoelectric or alternatively a photovoltaic mechanism to generate electricity needed to power said device. Semiconductors of both the p-type and n-type are known as possible energy harvesting means. Semiconductor materials used in electronic devices are routinely doped under controlled conditions in order to control regions of n-type and p-type since the p-n junctions between such regions provide, in use, exploitable electronic behavior.

Transition metal dichalcogenides (TMDC) being in the family of 2D materials are known semiconductors of the type MX2, M being a transition metal and X being a chalcogen atom such that two layers of X surround one layer of M providing a sandwich arrangement. They are typically provided as monolayers, however, can also be provided as multilayers with differently tuned desirable properties.

TMDCs in their odd number of layers form, have been shown to have piezoelectric properties, however, this property alone is not versatile or efficient enough to provide sufficient electricity to power a commercially usable wearable device. This limits their inclusion in wearable devices despite having the advantage of being very thin and therefore unobtrusive to a user thereof. Typical wearable devices are noticeably obtrusive to the user which is inimical especially when the wearable device has a medical application that the user does not want to display and would prefer to keep confidential.

Generally, energy harvesting wearable devices are known. US Patent No. 7,645,246 provides a method for generating power from an exerted energy associated with muscles acting across a joint. US 8,299,634 provides an apparatus for harvesting energy from motion of one or more joints. Movement at or about a human joint is required to generate power. WO2016/187536 provides for an ultra-thin sensing device typically sensing biological signals. In the aforementioned art there is no combination of piezoelectric and photovoltaic effects in generation of energy.

TMDCs have also been shown to have photovoltaic effects but require a rigid substrate that cannot readily be bent or strained. Any bending or strain diminishes their efficacy since the energic band gap of the TMDC is naturally influenced by such bending and strain wherein excitonic and absorbance resonance shifts toward the infra-red region of the light spectrum, and therefore away from the visible region of the light spectrum where the bulk of intensity of natural and artificial light is. and which is required for efficient photovoltaic effect. Consequently, the application of TMDCs in wearable devices as energy harvesters has limited potential since absorbance resonances often shift in order of hundreds of meV per percent strain on the TMDC making them completely unsuitable for wearable photovoltaic device. This is particularly disadvantageous for skin wearable devices and/or clothing wearable devices that require a great deal of mechanical deformation, resilience and/or bending as part of their usual use. Furthermore, deformation of the TMDC creates separation between the n-type and p-type regions which further diminishes charge transfer efficiencies. Consequently, the use of TMDC in photovoltaic applications are limited.

Typically, different TMDC 2D materials are used to provide p-type regions which causes reduced functionality when deformation occurs since the two materials separate to a greater extent when compared to a 2D material that is doped differently to provide different p-type and n-type regions.

There is a need for energy harvesting wearable devices that are thin, unobtrusive to a user, readily deformable and/or resilient, and both have piezoelectric and photovoltaic properties to ensure a constant, sufficient and reliable energy source to power such wearable devices. There is further a need to provide an energy harvesting wearable device that could readily be integrated with other electronic device and/or sensing devices.

There is a need to ameliorate at least one of the problems described above and/or otherwise known in the prior art.

SUMMARY

In accordance with a first aspect of this disclosure there is provided an energy harvesting wearable device comprising: a resilient polymer substrate; a p-type semiconductor abutting against an n-type semiconductor so as to form p-n junctions therebetween, both the p-type and n-type semiconductors being received onto the resilient polymer substrate; a first and second electrical contact abutting against p-type and n-type semiconductors, respectively, such that each of the first and second electrical contacts are at least partially received onto the resilient substrate; a dielectric insulator material superposingly abutting both the p-type and n-type semiconductors and concomitantly abutting against both the first and second electrical contacts; and a supercapacitor superposingly abutting against the dielectric insulator material and contacting both the first and second electrical contacts, wherein the supercapacitor is at least partially translucent and/or transparent, such that in use, visible light may pass through the supercapacitor, through the dielectric material and toward the p-type and n-type semiconductors to provide electrical charge via the photovoltaic effect whilst any mechanical deformation of the device provides further electrical charge via the piezoelectric effect, wherein the generated electrical charge is conducted via the first and second contacts to power an electronic device and/or charge the supercapacitor.

The p-type and n-type semiconductors may be configured to provide heterojunctions wherein the p-type and n-type are different materials. Alternatively, wherein the p-type and n-type semiconductors are configured to provide homojunctions wherein the p-type and n-type semiconductors comprise the same material but doped differently in order to provide in use a p-type region and an n-type region.

The abutment of the p-type and n-type semiconductors may be lateral abutment to provide lateral heterostructures or lateral homojunctions. The lateral abutment, in use, facilitates reduced thickness providing for a thin energy harvesting wearable device that is ergonomic, comfortable and unobtrusive to a user thereof.

The energy harvesting wearable device wherein the p-type and n-type semiconductors may both be transition metal dichalcogenides (TMDC).

The TMDCs may be of the type MX ₂ , M being a transition metal and X being a chalcogen atom such that two layers of X surround one layer of M providing a sandwich arrangement. M may typically be, but is not limited to, Mo (molybdenum), W (tungsten) and/or Re (Rhenium). X may typically be, but is not limited to, S (sulphur), Se (selenium) and/or Te (tellurium).

The TMDCs may be provided as a monolayer or alternatively as an odd number of layers. The dielectric insulator material may, but is not limited to, hexagonal boron nitride (h-BN) and two dimensional 2D materials having dielectric properties whilst concomitantly being optically inert.

The Applicant unexpectedly and surprisingly found that the redshift of absorbance resonances associated with mechanical deformation of the semiconductors when exploiting the photovoltaic effect is ameliorated by the presence of the dielectric insulating material. The dielectric insulating material changes the dielectric environment of exciton wavefunction. The exciton wavefunction are consequently long enough to penetrate the semiconductor monolayers and multilayers. The change in the dielectric environment provides formation of excitons which have bigger intensity and smaller linewidth which overcomes the negative effects of redshift. In so doing, the semiconductor (typically TMDC) provides both photovoltaic and piezoelectric effects sufficient to power an energy harvesting wearable device that is thin, unobtrusive to a user, readily deformable and/or resilient.

The dielectric insulating material further provides, in use, adherence to both the first and second contacts and also to the semiconductors which reduce the likelihood of separation and/or breakage between the p- type and n-type semiconductors and/or separation and/or breakage between the semiconductors and the first and second contacts. The dielectric insulating material also provides efficient strain transfer from substrate in order to deform material to be able to generate electric charge to piezoelectric effect.

The first and second contacts may include a conductive material, typically, but not limited to graphene, Au (gold), Ag (silver), Pt (platinum), Cr (chromium), conductive 2D materials, and argon plasma treated or ozone plasma treated semiconducting 2D materials. The 2D materials may be the same or different to the semiconductors. The 2D materials may be TMDCs as provided herein or different from what is provided herein. It is to be understood that other conductive materials are envisaged to fall within the ambit of this disclosure.

The supercapacitor includes electrodes and electrolytes connected to the first and second contacts. The electrodes and electrolytes are at least partially transparent and/or translucent to allow the passage of visible light therethrough. The electrodes may be, but is not limited to, graphene, graphene oxide and 2D materials. The electrolytes may be at least partially translucent and/or transparent.

The resilient polymer layer may include, but is not limited to, PMMA (polymethyl methacrylate), PET (polyethylene terephthalate), PI (polyimide), PC (polycarbonate), PDMS (polydimethyl siloxane) and PEN (polyethylene naphthalate), and/or combinations of the aforementioned. It is to be understood that the polymer layer may comprise other resilient polymers known in the art. The resilient polymer layer may in use adhere to human skin via electrostatic forces. When the energy harvesting wearable device is in use deformation of the p-type and n-type semiconductors results in generation of an electrical charge since the p-type and n-type semiconductors are non-centrosymmetric and have no inversion symmetry. This piezoelectric effect results in charge transferred to the first and second contacts in order to power an electronic device, and/or to charge the supercapacitor. Concomitantly, the energy harvesting wearable device allows for visible light penetration through the supercapacitor, dielectric insulating material and onto the semiconductors providing an electric charge generation through the photovoltaic effect without the negative red shift normally encountered by deformation of the semiconductors.

In a preferred embodiment, the energy generated via either the piezoelectric or photovoltaic effect is sufficient to power an electronic device whilst any excess is stored in the supercapacitor. It is to be understood that the stored excess may in use be utilized when there is no active energy generation, for example when the user of the device is in the dark and/or motionless.

The energy harvesting wearable device may be connected to at least one of a variety of monitoring means and/or communication devices. The monitoring means may include for example medical monitoring means. The communication devices may include telecommunication devices, smart device, wireless devices, and the like. The aforementioned may include 2D materials or classic electronics.

There is also provided for a skin patch comprising the device of this disclosure described herein. The skin patch for use on an animal or human body wherein the skin patch may adhere to a for example, but not limited to, a finger, a hand, an arm, a foot, a leg, a chest, a back, a face or other portion of the animal or human anatomy. The skin patch may be configured to provide vertical dimensions (height or thickness) of between about lOOnm to about 500nm. The skin patch may be configured to provide a variety of lateral dimensions. Lateral of the skin patch (when considering a top view) may be from about 5mm x about 5mm (as a square) to about 30cm x about 30cm (and anything therebetween). It is to be understood that the dimensions may even be smaller or greater depending on the application in use.

Typically the skin patch includes the energy harvesting wearable device of this disclosure, wherein said skin patch includes a vertical height (or thickness) of between lOOnm to 500nm, such that in use, the skin patch is applied to the skin of a human or animal body.

There is also provided for a method of manufacturing the energy harvesting wearable device as described herein, the method comprising the following steps:

(i) providing the resilient polymer substrate; (ii) adhering the p-type and n-type semiconductors, which are formed via for example stamping, chemical vapor deposition (CVD) and/or engineering of p and n type regions in same material, onto the resilient polymer substrate;

(iii) providing the first contact to abut against the p-type semiconductor and the second contract to abut against the n-type semiconductor whilst concomitantly providing contract between the first and second contacts with the resilient polymer substrate;

(iv) adhering the dielectric insulator material to superposingly abut against both the p-type and n-type semiconductors and concomitantly abutting against both the first and second electrical contacts; and

(v) adhering the supercapacitor to superposingly abut against the dielectric insulator material and contacting both the first and second electrical contacts.

There is further provided for energy harvesting wearable device according to this disclosure substantially as herein described, illustrated and/or exemplified with reference to any one of the accompanying diagrammatic drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described below by way of example only and with reference to the accompanying diagrammatic drawings in which:

FIGURE 1 shows a cross-sectional first side view of an energy harvesting wearable device according to this disclosure;

FIGURE 2 shows a three dimensional view of the energy harvesting wearable device;

FIGURE 3 shows a top view of the energy harvesting wearable device;

FIGURE 4 shows a bottom view of the energy harvesting wearable device; and

FIGURE 5 shows a cross-sectional second side view of the energy harvesting wearable device.

DETAIUED DESCRIPTION

The Summary of the disclosure is repeated hereunder by way of reference thereto only to avoid repetition. Like structural elements in the different embodiments are provided with like or corresponding reference numerals in as far as is possible.

This disclosure provides an energy harvesting wearable device 10 shown generally in Figures 1 to 5. Figure 1 shows a cross-sectional first side view of an energy harvesting wearable device 10. The device 10 is shown to comprise a resilient polymer substrate 12. Adhering to a region of a top surface 14 of the polymer substrate 12 is a p-type semiconductor 16 abutting against an n-type semiconductor 18 so as to form p-n junctions 20 therebetween. Both the p-type 16 and n-type 18 semiconductors being received onto the top surface 14 of the resilient polymer substrate 12. In use the bottom surface 22 of the resilient polymer substrate 12 is placed onto a user typically the users skin (not shown). Typically, the device 10 may be placed onto a skin surface of a user which is conventionally a human being. The skin surface may be in numerous parts of the human body such as the arm, leg, hand, and the like. The skilled person would appreciate that various placements would be possible without departing from the overall ambit of this disclosure.

The device 10 further comprises a first and second electrical contact 24,26 abutting against p-type and n- type semiconductors 16,18, respectively, such that each of the first and second electrical contacts 24,26 are at least partially received onto the top surface 14 of the resilient polymer substrate 12.

Figures 1 and 2 further show that the device 10 further comprises a dielectric insulator material 28 superposingly abutting both the p-type and n-type semiconductors 16,18 and concomitantly abutting against both the first and second electrical contacts 24,26.

A supercapacitor 30 is shown to superposingly abut against the dielectric insulator material 28 and contacting both the first and second electrical contacts 24,26. In a preferred embodiment the supercapacitor 30 is at least partially translucent and/or transparent. The supercapacitor 30 includes electrodes 32 and electrolytes 34 connected to the first and second contacts 24,26. The electrodes 32 and electrolytes 34 are at least partially transparent and/or translucent to allow the passage of visible light therethrough. The electrodes 32 may be, but is not limited to, graphene, graphene oxide and 2D materials. The electrolytes may be at least partially translucent and/or transparent.

When the device 10 is in use, visible light may pass through the supercapacitor 30, through the dielectric material 28 and toward the p-type and n-type semiconductors 16,18 to provide electrical charge via the photovoltaic effect whilst any mechanical deformation of the device provides further electrical charge via the piezoelectric effect. The generated electrical charge is conducted via the first and second contacts 24,26 to power another electronic device (not shown) and/or charge the supercapacitor 30. It is to be understood that another electronic device may be attached to the device 10 and may include at least one of a variety of monitoring means and/or communication devices (not shown). The monitoring means may include for example medical monitoring means. The communication devices may include telecommunication devices, smart device, wireless devices, and the like. The p-type and n-type semiconductors 16,18 may be configured to provide heterojunctions wherein the p-type and n-type are different materials. Alternatively, wherein the p-type and n-type semiconductors 16,18 are configured to provide homojunctions wherein the p-type and n-type semiconductors 16,18 comprise the same material but doped differently in order to provide in use a p-type region and an n-type region. The abutment of the p-type and n-type semiconductors 16,18 may be lateral abutment to provide lateral heterostructures or lateral homojunctions. The lateral abutment, in use, facilitates reduced thickness providing for a think energy harvesting wearable device that is ergonomic, comfortable and unobtrusive to a user thereof.

The p-type and n-type semiconductors 16,18 may both be transition metal dichalcogenides (TMDC). The TMDCs may be of the type MX2, M being a transition metal and X being a chalcogen atom such that two layers of X surround one layer of M providing a sandwich arrangement. M may typically be, but is not limited to, Mo (molybdenum), W (tungsten) and/or Re (Rhenium). X may typically be, but is not limited to, S (sulphur), Se (selenium) and/or Te (tellurium). The TMDCs may be provided as a monolayer or alternatively as an odd number of layers.

The dielectric insulator material 28 may be include, but is not limited to, hexagonal boron nitride (h-BN) and two dimensional 2D materials having dielectric properties whilst concomitantly being optically inert.

The first and second contacts 24,26 may include a conductive material, typically, but not limited to graphene, Au (gold), Ag (silver), Pt (platinum), Cr (chromium), conductive 2D materials, and argon or ozone plasma treated semiconducting 2D materials. The 2D materials may be the same or different to the semiconductors. The 2D materials may be TMDCs as provided herein or different from what is provided herein. It is to be understood that other conductive materials are envisaged to fall within the ambit of this disclosure.

The resilient polymer layer 12 may include, but is not limited to, PMMA (polymethyl methacrylate), PET (polyethylene terephthalate), PI (polyimide), PC (polycarbonate), PDMS (polydimethyl siloxane) and PEN (polyethylene naphthalate), and/or combinations of the aforementioned. It is to be understood that the polymer layer 12 may comprise other resilient polymers known in the art. The resilient polymer layer 12 may in use adhere to human skin via electrostatic forces.

It is to be understood that a variable number of devices 10 may be joined together in series and/or in parallel in order to generate electric charge as required for a specific monitoring means or communication means linked to the device 10. Figure 2 shows a three dimensional view of the energy harvesting wearable device 10. Figure 3 shows a top view of the energy harvesting wearable device 10 showing the supercapacitor 30 including electrodes 32 and electrolytes 34 (typically at least partially translucent and/or transparent). Figure 4 shows a bottom view of the device 10 which shows the bottom surface 22 of the resilient polymer layer 12 which typically in use will adhere to the skin of a user.

Figure 5 shows a cross-sectional second side view of the device 10. The device 10 is shown in Figures 1 to 4 to be rectangular. The second side view is a cross-sectional side view of the shorter sides of the rectangular formation and shows in Figure 5 the electrode 32, first contact 24 and resilient polymer layer 12

The Applicant unexpectedly and surprisingly found that the redshift of absorbance resonances associated with mechanical deformation of the semiconductors when exploiting the photovoltaic effect is ameliorated by the presence of the dielectric insulating material 28. The dielectric insulating material 28 changes the dielectric environment of exciton wavefimction. The exciton wavefimctions are consequently long enough to penetrate the semiconductors. The change in the dielectric environment provides formation of excitons which have bigger intensity and smaller linewidth which overcomes the negative effects of redshift. In so doing, the semiconductor 16,18 (typically TMDC) provides both photovoltaic and piezoelectric effects sufficient to power an energy harvesting wearable device and any other device linked thereto. The device 10 is thin, unobtrusive to a user, readily deformable and/or resilient.

The dielectric insulating material 28 further provides, in use, adherence to both the first and second contacts 24,26 and also to the semiconductors 16,18 which reduce the likelihood of separation and/or breakage between the p-type and n-type semiconductors 16,18 and/or separation and/or breakage between the semiconductors 16,18 and the first and second contacts 24,26.

When the energy harvesting wearable device 10 is in use deformation of the p-type and n-type semiconductors 16,18 results in generation of an electrical charge since the p-type and n-type semiconductors 16,18 are non-centrosymmetric and have no inversion symmetry. This piezoelectric effect results in charge transferred to the first and second contacts 24,26 in order to power an electronic device, and/or to charge the supercapacitor 30. Concomitantly, the energy harvesting wearable device 10 allows for visible light penetration through the supercapacitor 30, dielectric insulating material 28 and onto the semiconductors 16,18 providing an electric charge generation through the photovoltaic effect without the negative red shift normally encountered by deformation of the semiconductors 16,18. In a preferred embodiment, the energy generated via either the piezoelectric or photovoltaic effect is sufficient to power an electronic device whilst any excess is stored in the supercapacitor 30.

There is also provided for a skin patch comprising the device 10 of this disclosure described herein (although it is not specifically illustrated in the figures). The skin patch may be for use on an animal or human body, wherein the skin patch may adhere to a for example, but not limited to, a finger, a hand, an arm, a foot, a leg, a chest, a back, a face or other portion of the animal or human anatomy. The skin patch may be configured to provide vertical dimensions (height or thickness) of between about lOOnm to about 500nm. The skin patch may be configured to provide a variety of lateral dimensions. Lateral of the skin patch (when considering a top view) may be from about 5mm x about 5mm (as a square) to about 30cm x about 30cm (and anything therebetween). It is to be understood that the dimensions may even be smaller or greater depending on the application in use.

There is also provided for a method of manufacturing the energy harvesting wearable device 10 as described and/or illustrated herein, the method comprising the following steps:

(i) providing the resilient polymer substrate;

(ii) adhering the p-type and n-type semiconductors, which are formed via stamping, chemical vapor deposition (CVD) and/or engineering of p and n type regions in same material, onto the resilient polymer substrate;

(iii) providing the first contact to abut against the p-type semiconductor and the second contract to abut against the n-type semiconductor whilst concomitantly providing contract between the first and second contacts with the resilient polymer substrate;.

(iv) adhering the dielectric insulator material to superposingly abut against both the p-type and n-type semiconductors and concomitantly abutting against both the first and second electrical contacts; and

(v) adhering the supercapacitor to superposingly abut against the dielectric insulator material and contacting both the first and second electrical contacts..

In a certain embodiment, when the contacts comprise 2D materials (and different 2D material from the semiconductors) they may be formed by a stamping or CVD method. Where the contacts are the same 2D material as the semiconductors they can be treated with for example, argon plasma to change their phase from semiconducting to mettalic-conductive. In the event that the contacts comprise noble metals they are made with lithographic techniques and evaporation of the said noble metals.

It is to be understood that dielectric insulators are adhered semiconductors via a stamping or CVD method. Supercapacitors are typically manufactured using a stamping process or CVD. The Applicant has surprisingly and unexpected found that the device according to this disclosure ameliorates at least some of the disadvantages known from the prior art. While the disclosure has been described in detail with respect to specific embodiments and/or examples thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily conceive of alterations to, variations of and equivalents to these embodiments. Accordingly, the scope of the present disclosure should be assessed as that of the claims and any equivalents thereto, which claims are appended hereto.