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.

TMDCs 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.

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 visible light region 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 wearable devices for attachment to clothing 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.

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.

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, and particularly energy harvesting wearable devices that are readily integrated into fabric and/or articles of clothing.

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 this disclosure there is provided an energy harvesting wearable device comprising: a p-type semiconductor abutting against an n-type semiconductor so as to form p-n junctions there between; a dielectric insulator material abutingly sandwiching the p-type and n-type semiconductors; a first and second pair of electrical contacts abutting against p-type and n-type semiconductors, respectively, such that each of the first and second pair of electrical contracts at least partially abut against the dielectric insulating material; and a pair of supercapacitors abutingly sandwiching the dielectric insulator material and contacting both the first and second pairs of electrical contacts, wherein the pair of supercapacitors is at least partially translucent and/or transparent, such that in use, visible light may pass through the pair of supercapacitors, through the dielectric insulator 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 generation of electrical charge via the piezoelectric effect, wherein the generated electrical charge is conducted via the first and second pair of contacts to power an electronic device and/or charge the pair of supercapacitors.

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 vertical abutment to provide vertical heterostructures or vertical homojunctions.

The energy harvesting wearable device is configured to allow attachment onto fabric, typically, clothing so as to allow an ergonomic, comfortable and unobtrusive wearable device.

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 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 Re (Rhenium). X may typically be, but is not limited to, S (sulphur), Se (selenium) and Te (tellurium).

The TMDCs may be provided as a monolayer or alternatively as an odd number of layers.

The dielectric insulator material may 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 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 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 (typically TMDC) provides both photovoltaic and piezoelectric effects sufficient to power an energy harvesting wearable device that is thin and unobtrusive to a user when attached to a fabric or article of clothing.

The dielectric insulating material further provides, in use, adherence to both the first and second pairs of 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 pairs of contacts.

The first and second pairs of 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. It is to be understood that other conductive materials are envisaged to fall within the ambit of this disclosure.

Each of the pair of supercapacitors includes electrodes and electrolytes, one of the pair of supercapacitors connect to the first pair of contacts, and the second of the pair of supercapacitors connected to the second pair of 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.

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 pairs of contacts in order to power an electronic device, and/or to charge the pair of supercapacitors. Concomitantly, the energy harvesting wearable device allows for visible light penetration through the supercapacitors, 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 supercapacitors. 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. Further, the device may be integrated into clothing and/or fabric.

There is also provided for a smart fabric, the smart fabric including the energy harvesting wearable device as described herein. The fabric may be an item of clothing or part of an item of clothing. The fabric may also be a covering (or partial covering) for an animal or human body.

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

(i) providing the p-type and n-type semiconductors, which are formed via stamping or chemical vapor deposition;

(ii) adhering a first and second pair of electrical contacts to abut against a portion of opposite ends of the p-type and n-type semiconductors;

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

(iv) adhering the pair of supercapacitors to sandwiching abut against the dielectric insulator material and contacting both the first and second pair of 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; and FIGURE 4 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 4. Figure 1 shows a cross-sectional first side view of an energy harvesting wearable device 10.

The energy harvesting wearable device 10 is shown in Figures 1 and 2 to comprise a p-type semiconductor 16 abutting against an n-type semiconductor 18 so as to form p-n junctions 20 therebetween. The device 10 further includes a dielectric insulator material 28 abutingly sandwiching the p-type and n-type semiconductors 16,18. Figures 1 and 2 shows a first pair of electrical contacts 24 abutting against p-type semiconductors 16, and further shows that a second pair of electrical contacts 26 abutting against the n-type semiconductor 18. Each of the first and second pair of electrical contracts 24,26 is shown to at least partially abut against the dielectric insulating material 28. The device 10 further comprises a pair of supercapacitors 30.1, 30.2 abutingly sandwiching the dielectric insulator material 28 and contacting both the first and second pairs of electrical contacts 24,26, wherein the pair of supercapacitors 30.1, 30.2 is at least partially translucent and/or transparent.

When the device 10 is in use, visible light may pass through the pair of supercapacitors 30.1, 30.2, through the dielectric insulator 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 10 provides further generation of electrical charge via the piezoelectric effect, wherein the generated electrical charge is conducted via the first and second pair of contacts 24,26 to power an electronic device (not shown) and/or charge the pair of supercapacitors 30.1, 30.2. 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 are configured to provide homoj unctions 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 vertical abutment to provide vertical heterostructures or vertical homojunctions. The vertical junctions are shown in Figures 1 and 2.

The energy harvesting wearable device 10 is configured to allow attachment onto fabric, typically, clothing so as to allow an ergonomic, comfortable and unobtrusive wearable device.

Typically, 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 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 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 28 changes the dielectric environment of exciton wavefunction. The exciton wavefunction are consequently long enough to penetrate the semiconductors 16,18. 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) 16,18 provides both photovoltaic and piezoelectric effects sufficient to power an energy harvesting wearable device 10 that is thin and unobtrusive to a user when attached to a fabric or article of clothing.

The dielectric insulating material 28 further provides, in use, adherence to both the first and second pairs of contacts and also to the semiconductors 16,18 which reduces 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 pairs of contacts 24,26. The first and second pairs of 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.

Each of the pair of supercapacitors 30.1, 30.2 includes electrodes 32 and electrolytes 34. One of the pair of supercapacitors 30.1 connects to the first pair of contacts 24, and the second of the pair of supercapacitors 30.2 connects to the second pair of contacts 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 34 may be at least partially translucent and/or transparent.

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 pairs of contacts 24,26 in order to power an electronic device (not shown), and/or to charge the pair of supercapacitors 30.1, 30.2. Concomitantly, the energy harvesting wearable device 10 allows for visible light penetration through the supercapacitors 30.1, 30.2, 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 (not shown) whilst any excess is stored in the supercapacitors 30.1, 30.2.

The device 10 may be connected to at least one of a variety of electronic devices consisting of monitoring means and/or communication devices (not shown in the figures). The monitoring means may include for example medical monitoring means. The communication devices may include telecommunication devices, smart device, wireless devices, and the like

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 (not shown) 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. A bottom view will be similar.

Figure 4 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 4, from top to bottom, a portion of the first pair of contacts 24, the p-type semiconductor 16, the n-type semiconductor 18, and a portion of the second pair of contacts 26.

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 wavefunction. 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 dielectric insulating material 28 further provides, in use, adherence to both the first and second pairs of 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 pairs of 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 pairs of contacts 24,26 in order to power an electronic device (not shown), and/or to charge the supercapacitor 30. Concomitantly, the energy harvesting wearable device 10 allows for visible light penetration through the supercapacitors 30.1, 30.2, 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 supercapacitors 30.1, 30.2.

There is also provided for a smart fabric (not illustrated in the accompanying figures), the smart fabric including the energy harvesting wearable device as described herein. The fabric may be an item of clothing or part of an item of clothing. The fabric may also be a covering (or partial covering) for an animal or human body. It is to be understood that numerous different textiles are envisaged. Integration of the device into fabric may be, for example, via sowing, stitching, knitting, or adhesion.

There is also provided for a method of manufacturing the energy harvesting wearable device of this disclosure, the method comprising the following steps:

(i) providing the p-type and n-type semiconductors, which are formed via stamping or chemical vapor deposition;

(ii) adhering a first and second pair of electrical contacts to abut against a portion of opposite ends of the p-type and n-type semiconductors;

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

(iv) adhering the pair of supercapacitors to sandwiching abut against the dielectric insulator material and contacting both the first and second pair of electrical contacts.

Typically, the first and second pair of contacts are manufactured using a stamping technique or via chemical vapor deposition (CVD) for 2D materials, and lithography for types of contacts that include noble metals (usually on a wafer or wafer like substrate). Electrodes are then usually manufactured using stamping or CVD. The electrolytes are deposited together with the dielectric material usually via a stamping process. The p-type and n-type semiconductors are formed in vertical hetero or homo structures with a stamping process or CVD. The supercapacitor is typically deposited according to known means in the art of endeavor.

Once the device has been manufactured is ready to be incorporated or integrated into different sensing or other electronic devices and/or embedded into a fabric to provide the smart fabric.

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.