WO2024178015A1

WO2024178015A1 - Haptic wetness/fullness indicator pad

Info

Publication number: WO2024178015A1
Application number: PCT/US2024/016554
Authority: WO
Inventors: Tarique PERERA; Sachithra PRATHAPASINGHE; Achala SATHARASINGHE; Udara PULAJITH; Niranjan PITIDUWAMADDUMA
Original assignee: Mas Innovation Pvt Ltd; Piper Michael
Current assignee: Mas Innovation Pvt Ltd; Piper Michael
Priority date: 2023-02-20
Filing date: 2024-02-20
Publication date: 2024-08-29
Anticipated expiration: 2025-08-20

Abstract

Disclosed herein is a wetness indicating pad for use in a garment comprising a substrate material layer; and at least one liquid responsive indicator located on, integrally formed with, or located within a depression in the substrate material layer, wherein: the at least one liquid responsive material is positioned so as to provide an indication of the partial or complete fullness of the substrate material layer by a user when the absorbent pad is worn on a body of the user; and the liquid responsive indicator material changes at least one physical property upon absorbing a liquid, which change is detectable by touch by a user wearing the absorbent pad. Also disclosed herein are garments that comprise said wetness indicating pad.

Description

HAPTIC WETNESS/FULLNESS INDICATOR PAD

Field of Invention

The current invention relates to a wetness indicating pad that can be used in a garment. The pad incorporates a liquid responsive material that material changes at least one physical property upon absorbing a liquid, which change is detectable by touch by a user wearing the absorbent pad and which is located in such a manner to indicate that the pad is full (i.e. saturated with a liquid) or is approaching this status. The invention also relates to garments that incorporate said wetness indicating pad.

Background

The listing or discussion of a prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge.

Current products for indicating the level of wetness or fullness in various products, such as disposable diapers and period winglets/panties, have significant limitations. In the first instance, a user can simply wait until they start to feel wet, meaning that the product has reached its ultimate capacity. This is not ideal, as it may mean that the user needs to quickly change the product and may not be in a place where this is readily possible to do.

Alternatively, simple visual inspection of the product may be used to gauge fullness of the product, but this requires being in a place that allows visual inspection, which may not always be possible. In addition, depending on the fluid that is being tracked, simple visual inspection might not enable one to see the level of fullness of the product. While an irreversible hydrochromic ink may be used that changes colour when a fluid makes contact with it, this is also limited to visual inspection.

Finally, some electronic devices that give an indication based on physical property variations (e.g. resistance, capacitance, ultrasonic, etc,) can be fitted to the garment. These may be bulky or make the user uncomfortable, In addition, if the electronic device is intended to be reusable (in whole or in part), then it may need to be connected to and removed from the product, causing additional inconvenience for the user. It is therefore an objective of the present invention to provide a product that provides a more reliable and accurate means of indicating the level of wetness or fullness in various products.

Summary of Invention

It has been surprisingly found that using strategic, calculated placement of at least one liquid responsive indicator (such as a super absorbent polymer (SAP), like sodium polyacrylate) on and/or around a fabric/substrate layer, the product is able give the wearer an indication of the level of wetness/fullness in the form of a change in haptic properties of the fabric/ substrate during use.

Aspects and embodiments of the invention will now be discussed by reference to the following numbered clauses.

1. A wetness indicating pad for use in a garment comprising: a substrate material layer; and at least one liquid responsive indicator located on, integrally formed with, or located within a depression in the substrate material layer, wherein: the at least one liquid responsive material is positioned so as to provide an indication of the partial or complete fullness of the substrate material layer by a user when the absorbent pad is worn on a body of the user; and the liquid responsive indicator material changes at least one physical property upon absorbing a liquid, which change is detectable by touch by a user wearing the absorbent pad.

2. The wetness indicating pad according to Clause 1 , wherein the at least one physical property is selected from a group consisting of stiffness, hardness and physical dimensions.

3. The wetness indicating pad according to Clause 1 or Clause 2, wherein the at least one liquid responsive indicator is responsive to a liquid comprising water, optionally wherein the liquid is a body fluid discharged from the user, and further optionally the liquid is one or more of the group consisting of water, blood, sweat, tears, milk, and urine.

4. The wetness indicating pad according to any one of the preceding clauses, wherein the at least one liquid responsive indicator is formed from a super absorbent polymer, a pH responsive material, or a target protein responsive material. 5. The wetness indicating pad according to any one of the preceding clauses, wherein the at least one liquid responsive indicator is formed from a super absorbent polymer, optionally wherein the superabsorbent polymer is sodium polyacrylate.

6. The wetness indicating pad according to any one of the preceding clauses, wherein the wetness indicating pad comprises two or more liquid responsive indicators that are located at various positions so as to provide a staged indication of fullness of the wetness indicating pad.

7. The wetness indicating pad according to any one of the preceding clauses, wherein the substrate material layer is formed from one or more of a fabric, a plastic sheet, a foam, and a metal foil.

8. The wetness indicating pad according to any one of the preceding clauses, wherein when at least one of the at least one liquid responsive indicators is located within a depression in the substrate material layer then the at least one liquid responsive indicator has: an initial dry thickness that corresponds to the thickness of a surrounding portion of the substrate material layer, so that no perceived difference in thickness is felt by a user; or an initial dry thickness that is thinner than a surrounding portion of the substrate material layer, and when in contact with a liquid the at least one liquid responsive indicator swells to match or exceed a thickness of the surrounding portion of the substrate material layer.

9. The wetness indicating pad according to any one of the preceding clauses, wherein the substrate material layer is an absorbent material layer and the wetness indicating pad further comprises a wicking layer and a liquid impermeable barrier layer, where the absorbent material layer; and the at least one liquid responsive indicator located on, integrally formed with, or located within a depression of the absorbent material layer are sandwiched between the wicking layer and the liquid impermeable barrier layer.

10. The wetness indicating pad according to Clause 9, wherein the at least one liquid responsive indicator faces towards the wicking layer.

11 . The wetness indicating pad according to Clause 9 or Clause 10, wherein the at least one liquid responsive indicator faces towards the liquid impermeable barrier layer. 12. The wetness indicating pad according to any one of the preceding clauses, wherein the pad is treated to have one or more of the group consisting of an anti-microbial property, durability enhancement, an anti-staining property, an anti-odour property and a fit and comfort enhancement.

13. The wetness indicating pad according to any one of the preceding clauses, wherein the pad further comprises a bistable compliant mechanism adapted to work in conjunction with the at least one liquid responsive indicator, where in a dry state the bistable compliant mechanism is provided in a first configuration and adopts a second configuration when the liquid responsive indicator material reaches a threshold value of the at least one physical property upon absorption of a liquid, wherein the change to the second configuration is accompanied by one or more of an audible snap, a an audible click, and a discrete protrusion, optionally wherein the bistable compliant mechanism is a contour clip.

14. The wetness indicating pad according to any one of the preceding clauses, wherein the pad is reusable and machine washable, optionally wherein the pad is capable of surviving at least 25 machine wash and dry cycles.

15. A garment comprising a wetness indicating pad as described in any one of Clauses 1 to 14.

16. The garment according to Clause 14, wherein the garment is selected from a group consisting of underwear and outerwear, such as a period panty, a urinary incontinence underwear, a reusable diapers, and a maternity bra.

Drawings

Figure 1 depicts a wetness indicating pad according to an embodiment of the current invention.

Figure 2 depicts a wetness indicating pad according to an embodiment of the current invention.

Figure 3 depicts a wetness indicating pad according to an embodiment of the current invention.

Figure 4 depicts a wetness indicating pad according to an embodiment of the current invention. Figures 5A-5F depict a wetness indicating pad according to an embodiment of the current invention, and show in cartoon form how the pad enables a wearer to feel when the pad is approaching being full with liquid through touch.

Figures 6A-6G depict various configurations of wetness indicating pad according to embodiments of the current invention.

Description

For purposes of brevity and clarity, descriptions of embodiments of the present disclosure are directed to a wetness indicating pad (e.g. for use in a garment), in accordance with the drawings. While aspects of the present disclosure will be described in conjunction with the embodiments provided herein, it will be understood that they are not intended to limit the present disclosure to these embodiments. On the contrary, the present disclosure is intended to cover alternatives, modifications and equivalents to the embodiments described herein, which are included within the scope of the present disclosure as defined by the appended claims. Furthermore, in the following detailed description, specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be recognized by an individual having ordinary skill in the art, i.e. a skilled person, that the present disclosure may be practiced without specific details, and/or with multiple details arising from combinations of aspects of particular embodiments. In a number of instances, known systems, methods, procedures, and components have not been described in detail so as to not unnecessarily obscure aspects of the embodiments of the present disclosure.

In embodiments of the present disclosure, depiction of a given element or consideration or use of a particular element number in a particular figure or a reference thereto in corresponding descriptive material can encompass the same, an equivalent, or an analogous element or element number identified in another figure or descriptive material associated therewith.

References to “an embodiment I example”, “another embodiment I example”, “some embodiments / examples”, “some other embodiments / examples”, and so on, indicate that the embodiment(s) I example(s) so described may include a particular feature, structure, characteristic, property, element, or limitation, but that not every embodiment I example necessarily includes that particular feature, structure, characteristic, property, element, or limitation. Furthermore, repeated use of the phrase “in an embodiment I example” or “in another embodiment I example” does not necessarily refer to the same embodiment I example.

The terms “comprising”, “including”, “having”, and the like do not exclude the presence of other features I elements I steps than those listed in an embodiment. Recitation of certain features I elements I steps in mutually different embodiments does not indicate that a combination of these features I elements I steps cannot be used in an embodiment. The terms “a” and “an” are defined as one or more than one. The use of 7” in a figure or associated text is understood to mean “and/or” unless otherwise indicated. The recitation of a particular numerical value or value range herein is understood to include or be a recitation of an approximate numerical value or value range.

In a first aspect of the invention, there is provided a wetness indicating pad for use in a garment comprising: a substrate material layer; and at least one liquid responsive indicator located on, integrally formed with, or located within a depression in the substrate material layer, wherein: the at least one liquid responsive material is positioned so as to provide an indication of the partial or complete fullness of the substrate material layer by a user when the absorbent pad is worn on a body of the user; and the liquid responsive indicator material changes at least one physical property upon absorbing a liquid, which change is detectable by touch by a user wearing the absorbent pad.

In embodiments herein, the word “comprising” may be interpreted as requiring the features mentioned, but not limiting the presence of other features. Alternatively, the word “comprising” may also relate to the situation where only the components/features listed are intended to be present (e.g. the word “comprising” may be replaced by the phrases “consists of’ or “consists essentially of’). It is explicitly contemplated that both the broader and narrower interpretations can be applied to all aspects and embodiments of the present invention. In other words, the word “comprising” and synonyms thereof may be replaced by the phrase “consisting of’ or the phrase “consists essentially of’ or synonyms thereof and vice versa.

The phrase, “consists essentially of’ and its pseudonyms may be interpreted herein to refer to a material where minor impurities may be present. For example, the material may be greater than or equal to 90% pure, such as greater than 95% pure, such as greater than 97% pure, such as greaterthan 99% pure, such as greaterthan 99.9% pure, such as greaterthan 99.99% pure, such as greater than 99.999% pure, such as 100% pure.

As noted above, the wetness indicating pad of the current invention includes at least one liquid responsive indicator. In embodiments of the invention, the at least one liquid responsive indicator may be responsive to a liquid comprising water. In particular embodiments of the invention that may be mentioned herein, the liquid may be a body fluid discharged from the user. In yet more particular embodiments of the invention that may be mentioned herein, the liquid may be one or more of the group consisting of water, blood, sweat, tears, milk, and urine.

The at least one liquid responsive indicator may be formed from any suitable material that can change at least one physical property upon absorbing a liquid, which change is detectable by touch by a user wearing the absorbent pad. For example, the at least one liquid responsive indicator may be formed from a super absorbent polymer, a pH responsive material, or a target protein responsive material. As will be appreciated, more than one liquid responsive indicator may be used in the pads of the current invention and each may be made from a different material discussed above or, possibly, a blend of the materials discussed above. In particular embodiments of the invention, the at least one liquid responsive indicator may be formed from a super absorbent polymer (SAP). Any suitable SAP may be used herein. An example of a suitable SAP that may be used herein is sodium polyacrylate. Other materials that may be used as the liquid responsive material (alone or in combination with a SAP) include, but are not limited to hydrogels, textile blends, and cellulosic absorbent fibers.

By careful placement of at least one liquid responsive indicator (such as a SAP like sodium polyacrylate) on and around the fabric layer, the pad of the current invention is able give the wearer an indication of the level of wetness/fullness in the form of change in haptic properties of the fabric/ substrate during use. This may be achieved through making use of the user’s sense of touch - this may be by the user using their hand to touch the pad (e.g. through their clothing) or simply by the way that the pad feels against the user’s skin. As noted above, at least one physical property of the liquid responsive indicator material changes upon absorbing a liquid. In embodiments of the invention that may be mentioned herein, the at least one physical property may be selected from one or more of a group consisting of stiffness, hardness and physical dimensions. For example, in a product using an SAP in one or more positions, the product is able to provide an indication of fullness to the user via touch as each SAP sections of the pad will start to change stiffness or dimensions as the liquid front makes contact with it. The liquid front may moves over the substrate material as it gets distributed (wicked) around the substrate (e.g. a fabric). Once the liquid front makes contact with the SAP, the SAP absorbs the liquid and starts to change stiffness and/or dimensions. This change of stiffness and/or dimensions can be felt by the wearer from either the surface next-to-skin or the surface from outside the garment, thus informing the wearer of the different levels of wetness/fullness, based on the level of swelling and/or stiffness change of a single or multiple material components.

This invention can be used to indicate a product’s wetness level and how much liquid is contained within itself, and can primarily be used on undergarments such as period panties, urinary incontinence underwear, reusable diapers and maternity bras, where moisture/liquid interaction with the garment is expected. Applications may also include but are not limited to rain and hiking gear and any products where liquid exposure is expected at some point during the product’s use.

As will be appreciated, the wetness indicating pad according to the current invention includes at least one liquid responsive indicator. As such, the wetness indicating pad may comprise two or more (e.g. 2, 3, 4, 5, 6, 7, 8, 9, 10 etc.) liquid responsive indicators that are located at various positions so as to provide a staged indication of fullness of the wetness indicating pad.

The substrate material may be formed from any suitable material or combination of materials. In certain embodiments, the substrate material may be formed from a material that can transfer liquid across itself and to the liquid responsive component. For example, the substrate material layer may be formed from one or more of a fabric, a plastic sheet, a foam, and a metal foil.

The wetness indicating pad may be provided in a variety of configurations. For example, wetness indicating pad according to any one of the preceding claims, wherein when at least one of the at least one liquid responsive indicators is located within a depression in the substrate material layer then the at least one liquid responsive indicator has: an initial dry thickness that corresponds to the thickness of a surrounding portion of the substrate material layer, so that no perceived difference in thickness is felt by a user; or an initial dry thickness that is thinner than a surrounding portion of the substrate material layer, and when in contact with a liquid the at least one liquid responsive indicator swells to match or exceed a thickness of the surrounding portion of the substrate material layer.

In certain embodiments of the invention, the substrate material layer may be an absorbent material layer (e.g. made from a fabric and/or a foam or the like) and the wetness indicating pad may further comprise a wicking layer and a liquid impermeable barrier layer, where the absorbent material layer, and the at least one liquid responsive indicator located on, integrally formed with, or located within a depression of the absorbent material layer are sandwiched between the wicking layer and the liquid impermeable barrier layer. In such embodiments, the at least one liquid responsive indicator may: face towards the wicking layer; or face towards the liquid impermeable barrier layer.

As will be appreciated, when the at least one liquid responsive indicator comprises two or more (e.g. 2, 3, 4, 5, 6, 7, 8, 9, 10 etc.) then each of these may have separate orientations.

The wicking layer may be made from fibres or yarns made with fibres, where said fibres and yarns are selected from one or more of the group consisting of polyamide, polyester, polyolefin, polyurethane, polyacrylonitrile, natural cellulose, regenerated cellulose, regenerated cellulose derivatives (i.e. cellulose acetate and cellulose triacetates), natural protein and regenerated protein. The wicking layer may be produced using technologies such as knitting (warp knitting such as raschel Tricot, weft knitting such as circular or flat), weaving, non-woven methods (blow spinning, staple nonwoven, spun laid, air-laid, needle punched, thermal bonded, hydroentangled, chemical bonded and so forth), electro-spinning, force-spinning etc. Additionally, the wicking layer may also include one or more of the coatings, treatments encapsulation or entrapments, which would enhance its liquid and moisture management functionality, such as rate of wicking, wicking capacity, rate of spreading and distribution, one-way liquid transport etc.

The material of the wicking layer may be naturally moisture-wicking and/or be treated to become moisture-wicking. For example, the wicking material may be 100% polyester fabric with French Terry knit and a denier differential across the two faces of the wicking layer that assists in moving the liquid from the skin-facing side of the wicking layer to the internal surface that is in contact with the absorbent layer. Other suitable wicking materials include blends of polyester, polypropylene, and cotton. An advantage associated with the use of a wicking layer having the triangular ridge structures of French Terry knitting facing the user’s skin is that less surface area of the surface of the wicking layer comes into contact with the skin and therefore reduces any sensation of feeling wetness against the skin.

As an example, the wicking layer may comprise a material that is 51 % cotton and one or both of the inner and outer surfaces of the wicking layer may be treated with a hydrophilic composition or material (e.g. polyethylene oxide, polyvinyl alcohol, polyacrylamide, poly acrylic acid, polyvinyl pyrrolidone, hydrophilic silicones, or hydrophilic polyurethanes) and/or a hydrophobic composition or material (e.g. silicones, polyfluoroalkylacrylates, polyacrylates, polyurethanes, or waxes) to create a net hydrophilic gradient across the wicking layer. In other words, the surface in direct contact with the user’s skin may be less hydrophilic (i.e. more hydrophobic) whereas the outer surface may be more hydrophilic. For example, the surface of the wicking layer in direct contact with the user’s skin may be treated with a hydrophobic material and/or the opposing surface may be treated with a hydrophilic material. This results in a combination of a "pushing" force generated by the hydrophobic properties of the surface in direct contact with the user's skin and a "pulling" force generated by the hydrophilic properties of the outer surface that may wick any moisture or liquid through the wicking layer and away from the user. The hydrophilic and hydrophobic compositions may be applied to the wicking layer using any conventional method known to the skilled person.

Additionally, the differential capillary forces on either side can be created bythe fabric structure of the wicking layer where one side of the wicking layer has a smaller pore size in comparison to the opposite side of the wicking layer. Ideally, this pore combination creates funnel-like structures through the wicking layer in cross-section, where the liquid is pulled from the side with the larger pore size to the side with the smaller pore size, due to the differential capillary pressure.

The rate of wicking through the wicking layer may be controlled to be faster or slower. The rate may be set at a maximum rate of absorption of the wicking layer to ensure that all, or a significant percentage of, the liquid is absorbed by the absorbent layer and does not leak beyond the confines of the garment. The rate of wicking may be controlled by the density, thickness, or composition of the wicking layer and/or by the amount and type of hydrophobic and/or hydrophilic material applied to the wicking layer. In another embodiment, the rate of wicking may be set such that the surface of the wicking layer in direct contact with the user feels "dry" or mostly dry to the user while the other surface may feel wet. In some embodiments, the wicking layer may include an antimicrobial agent or substance. For example, the antimicrobial substance may be one or more substances selected from the group consisting of a silver-containing substance, titanium dioxide, a quaternary silane, hydrogen peroxide, triclosan, and zinc pyrithione. Additionally or alternatively, the wicking layer may include an agent or substance that combats odour. For example, the substance that combats odour may be one or more substances selected from the group consisting of nanoparticles with acid-neutralising pockets, high surface area mineral compositions, high surface area ceramic compositions and high surface area clay compositions. Further additionally or alternatively, the wicking layer may include a stain-resistant or stain-proof agent or substance.

The absorbent layer may include any liquid absorbent I absorbing material known in the art (e.g. cotton, a cotton blend, foam, a synthetic material, absorbent polymeric foam, a nanotechnology-based or -produced material, or any other moisture-absorbent material). The material may have a weight of 50 to 500 g/m², such as 180 to 300 g/m². For example, the absorbent layer may be made from an 80:20 blend of polyester: nylon fabric with a microfiber double terry knit. Other suitable materials include polypropylene or any cellulose-based fabric and their blends including cotton, bamboo etc.

In some embodiments, the absorbent layer may be a 100% polyester double terry fabric. This material is approximately 90% air and so allows for a higher absorbent capacity, as moisture fills up the air gaps of the polyester terry fabric without significant expansion of the polyester fibres. This does not translate into significantly thicker absorbent pad 100.

In some embodiments, the absorbent layer may be made from a blended fibre comprising two or more of superabsorbent polymer (SAP), hydrogel and polyester, or at least part (e.g. the surface facing towards the fabric body 200 of the garment) of the absorbent layer may have been treated with SAP and/or hydrogel. In these embodiments, the use of these materials may result in increased liquid absorbent capacity, with a reduced thickness and weight for the absorbent pad 100, and in an improved dry feel on the surface of the wicking component 102 in contact with the user’s skin, due to an increased affinity in the absorbent layer.

The liquid impermeable barrier layer is leak-proof and may include any known wholly or partially liquid-blocking material. Preferably, the barrier layer is breathable, so that liquid may not pass through it, but gases (including water vapour) can do so. For example, the barrier layer may include one or more layers of a thermoplastic or thermoset film, where the thermoplastic or thermoset film is selected from one or more of the group consisting of polyurethane, polyester, polyolefin, and silicone. Particular examples of liquid impermeable materials include layers made from a liquid impermeable polymer or a thermoplastic polyurethane film.

In some embodiments, the barrier layer may be a liquid-proof membrane (such as a liquidproof membrane material supplied by Dingzing Advanced Materials Inc, Taiwan). The barrier layer may provide the advantage of being fully breathable in dry form, while providing an effective barrier material upon exposure to liquid.

In certain embodiments, the wetness indicating pad may be treated to have one or more of the group consisting of an anti-microbial property, durability enhancement, an anti-staining property, an anti-odour property and a fit and comfort enhancement.

In certain embodiments, the wetness indicating pad according to any one of the preceding claims, wherein the pad may further comprise a bistable compliant mechanism adapted to work in conjunction with the at least one liquid responsive indicator, where in a dry state the bistable compliant mechanism is provided in a first configuration and adopts a second configuration when the liquid responsive indicator material reaches a threshold value of the at least one physical property upon absorption of a liquid, wherein the change to the second configuration is accompanied by one or more of an audible snap, a an audible click, and a discrete protrusion. For example, the bistable compliant mechanism may be a contour clip.

For example, in a dry state, the bistable compliant mechanism is positioned in the pad such that its properties can be affected by the at least one liquid responsive indicator. Once the liquid responsive indicator absorbs liquid and changes its physical properties (e.g. its stiffness and/or its hardness) it forces the bistable compliant mechanism into its secondary stable position/orientation/shape, which would be detectable by the user in the form of a haptic or auditory feedback. For example if the bistable mechanism is a contour clip, this may be an audible snap.

In certain embodiments of the invention, the wetness indicating pad may be disposable. However, in further embodiments of the invention, the wetness indicating pad may be reusable and machine washable. In such embodiments, the pad may be capable of surviving at least 25 machine wash and dry cycles. An embodiment of the current invention is displayed in Fig. 1. In this figure, the wetness indicating pad 10 comprises a non-woven substrate 15 and a liquid responsive indicator 20 sandwiched inside the non-woven substrate 15. This pad may be bonded 35 to a body fabric of a garment 30 using any suitable bonding method (e.g. stitching, an adhesive, ultrasonic bonding or the like).

An embodiment of the current invention is displayed in Fig. 2. In this figure, the wetness indicating pad 10 comprises a substrate 15 and a liquid responsive indicator 20 laid at an end of the substrate layer. The liquid responsive indicator 20 may be bonded or attached to the substrate layer using any suitable means (e.g. stitching, adhesives, ultrasonic bonding or the like). In use, the liquid responsive indicator 20 will change its properties upon exposure to a liquid.

An embodiment of the current invention is displayed in Fig. 3. In this figure, the wetness indicating pad 10 comprises a substrate and a liquid responsive indicator 40 that are integrally formed as a single material. As will be noted, by reference to Fig. 2, the liquid responsive indicator material is integrated into the substrate layer at a particular position in order to provide an indication of fullness. This integration may be achieved through the use of any suitable means to achieve an integrated material formation. For example, the liquid responsive indicator material may be impregnated or form part of the substrate later material in the locations that it is desired to be present. This may be achieved by coating the liquid responsive indicator material onto the substrate material in such locations, by using knitting or weaving (e.g. coating the liquid responsive indicator material onto strands/yarns of the substrate layer material or using separate strands of the liquid responsive indicator material in conjunction with strands/yarns of the substrate material layer material).

An embodiment of the current invention is displayed in Fig. 4. In this figure, the wetness indicating pad 10 comprises a substrate in the form of an absorbent layer 15, a liquid responsive indicator 20 attached to the absorbent layer, a wicking layer 50 on one face of the absorbent layer and a liquid impermeable barrier layer 55 on the opposite face of the absorbent layer 20. The liquid responsive indicator 20 is shown as being attached to the face of the absorbent layer facing the liquid impermeable barrier layer 55, but it may also be attached to the surface facing the wicking layer 50. Indeed, in embodiments where there is more than one liquid responsive indicator 20, then a first liquid responsive indicator may be on the surface of the absorbent layer facing the liquid impermeable barrier layer, while a second liquid responsive indicator may be on the surface of the absorbent layer facing the wicking layer. An embodiment of the current invention is displayed in Figs. 5A-5F. In these figures, the wetness indicating pad 10 comprises a substrate layer 15, two liquid responsive indicators 20 and 25 are attached to the substrate layer. Fig. 5A represents an essentially unused/unsoiled pad. In use, the pad will be exposed to a liquid 60, initially in a small amount (Fig. 5B), but over time the amount of liquid expelled from the user onto the pad increases (Fig. 5C). As the liquid expelled from the user into the pad increases further the first liquid responsive indicator starts to undergo the physical transformation discussed hereinbefore. As depicted in Fig. 5D, only the region of the first liquid responsive indicator 20 in contact with the liquid (e.g. blood) undergoes a physical transformation, thereby starting to alert the wearer that the pad is starting to fill up. Similarly, when the liquid level increases further (Fig. 5E), the second liquid responsive indicator 25 only the portions in contact with the liquid undergoes a physical transformation, thereby indicating to the wearer that the pad is getting very full and should be changed soon. As show in Fig. 5F, the pad will continue to fill after the first and second liquid responsive indicators have undergone their physical transformations and give a strong indication to the wearer that the pad needs to be changed immediately.

Figures 6A to 6G provide various construction layups of the liquid responsive indicators on a substrate layer. In the embodiments shown, there may be one (Fig. 6F), two (Figs 6C, 6D and 6E), or four liquid responsive indicators (Figs. 6A, 6B and 6G) attached to the substrate layer in these embodiments. The black lines or circles represent the liquid responsive indicator materials. As can be seen, these can be provided in a line configuration or as a circle, combinations thereof or entirely different shapes, depending on what is seens as working best for the wearers.

In embodiments of the invention where the at least one liquid responsive indicator is not integrated into the substrate layer, then the at least one liquid responsive indicator may be encapsulated in a material similar to the substrate layer (or other component) so as to feel similar to a user. As will be appreciated, if the pad includes a wicking layer, or the at least one liquid responsive indicator is positioned so that it faces away from the body of a user while in use, then this is not something that is required.

In certain embodiments of the invention, the substrate layer may be the same material as the at least one liquid responsive indicator material. In such embodiments the areas that essentially act as the at least one liquid responsive indicator may be determined by said area reacting in a different or more exaggerated manner to the introduction of the liquid. This may be by the inclusion of physical restrictions on the rest of the substrate layer or by some form of shielding of the substrate layer (e.g. physical shielding or by a chemical coating, e.g. a hydrophobic treatment), such that only particular areas designated to act as liquid responsive indicators areas are susceptible to the ingress of liquid.

In a further aspect of the invention, there is provided a wetness indicating pad as described hereinbefore. In this aspect, the garment may be selected from a group consisting of underwear and outerwear. For example, a period panty, a urinary incontinence underwear, a reusable diapers, and a maternity bra. Other examples may include rain and hiking gear.

Claims

2. The wetness indicating pad according to Claim 1 , wherein the at least one physical property is selected from a group consisting of stiffness, hardness and physical dimensions.

3. The wetness indicating pad according to Claim 1 , wherein the at least one liquid responsive indicator is responsive to a liquid comprising water, optionally wherein the liquid is a body fluid discharged from the user, and further optionally the liquid is one or more of the group consisting of water, blood, sweat, tears, milk, and urine.

4. The wetness indicating pad according to Claim 1 , wherein the at least one liquid responsive indicator is formed from a super absorbent polymer, a pH responsive material, or a target protein responsive material.

5. The wetness indicating pad according to Claim 1 , wherein the at least one liquid responsive indicator is formed from a super absorbent polymer, optionally wherein the superabsorbent polymer is sodium polyacrylate.

6. The wetness indicating pad according to Claim 1 , wherein the wetness indicating pad comprises two or more liquid responsive indicators that are located at various positions so as to provide a staged indication of fullness of the wetness indicating pad.

7. The wetness indicating pad according to Claim 1 , wherein the substrate material layer is formed from one or more of a fabric, a plastic sheet, a foam, and a metal foil.

8. The wetness indicating pad according to Claim 1 , wherein when at least one of the at least one liquid responsive indicators is located within a depression in the substrate material layer then the at least one liquid responsive indicator has: an initial dry thickness that corresponds to the thickness of a surrounding portion of the substrate material layer, so that no perceived difference in thickness is felt by a user; or an initial dry thickness that is thinner than a surrounding portion of the substrate material layer, and when in contact with a liquid the at least one liquid responsive indicator swells to match or exceed a thickness of the surrounding portion of the substrate material layer.

9. The wetness indicating pad according to Claim 1 , wherein the substrate material layer is an absorbent material layer and the wetness indicating pad further comprises a wicking layer and a liquid impermeable barrier layer, where the absorbent material layer; and the at least one liquid responsive indicator located on, integrally formed with, or located within a depression of the absorbent material layer are sandwiched between the wicking layer and the liquid impermeable barrier layer.

10. The wetness indicating pad according to Claim 9, wherein the at least one liquid responsive indicator faces towards the wicking layer.

11. The wetness indicating pad according to Claim 9, wherein the at least one liquid responsive indicator faces towards the liquid impermeable barrier layer.

12. The wetness indicating pad according to Claim 1 , wherein the pad is treated to have one or more of the group consisting of an anti-microbial property, durability enhancement, an antistaining property, an anti-odour property and a fit and comfort enhancement.

13. The wetness indicating pad according to Claim 1 , wherein the pad further comprises a bistable compliant mechanism adapted to work in conjunction with the at least one liquid responsive indicator, where in a dry state the bistable compliant mechanism is provided in a first configuration and adopts a second configuration when the liquid responsive indicator material reaches a threshold value of the at least one physical property upon absorption of a liquid, wherein the change to the second configuration is accompanied by one or more of an audible snap, a an audible click, and a discrete protrusion, optionally wherein the bistable compliant mechanism is a contour clip.

14. The wetness indicating pad according to Claim 1 , wherein the pad is reusable and machine washable, optionally wherein the pad is capable of surviving at least 25 machine wash and dry cycles.

15. A garment comprising a wetness indicating pad as described in Claim 1 .

16. The garment according to Claim 14, wherein the garment is selected from a group consisting of underwear and outerwear, such as a period panty, a urinary incontinence underwear, a reusable diapers, and a maternity bra.