Technical Field

[0001] The present invention broadly relates to a customizable insert for a shoe, corresponding methods of producing personalised shoe inserts, and personalised shoe inserts produced by such methods.

Background of the Invention

[0002] Shoe inserts are useful for enhancing the fit and comfort of a shoe. They can be used to provide increased shock-absorption of a shoe, to provide a more comfortable sole material for contact with the foot, to improve pressure distribution across the sole of a shoe and foot, to improve the fit of a shoe or to enhance the ergonomics of the shoe interior around the shape of the foot.

[0003] Such features may be important for everyday comfort, or they may have further health implications. Poor fitting or uncomfortable shoes can cause, for example, orthopaedic and lower limb conditions. Shoe comfort also has an impact on a wearer’s mobility and their inclination and ability to walk or run, and as such a comfortable and well-fitting shoe can be crucial in encouraging regular walking to promote a healthy lifestyle and prevent health issues such as obesity and type 2 diabetes.

[0004] Given the wide variety in the shape of feet between individuals, the type of shoes worn, and the objectives when using a shoe insert, an off-the-shelf shoe insert will not perfectly suit all potential users and their choice of shoe. It is therefore desirable to be able to customize a shoe insert to suit a user’s particular foot and shoe shape.

[0005] Existing methods of providing customized shoe inserts are lengthy and costly, requiring specialised knowledge and manufacturing facilities. If custom-made insoles are prescribed, approximately 20-30 minutes for casting and several weeks (usually 6-10 weeks) for manufacturing is usually required. This delay can have a negative impact on symptoms and final prognosis.

[0006] It is therefore desirable to provide a shoe insert which may be customized without the need for specialist assistance and without the need for specialized manufacturing facilities, which can be customized quickly and cheaply by a user themselves.

Summary of the Invention

[0007] According to a first aspect, the present invention provides an insert for a shoe comprising: a top layer which, when in use, faces the sole of a user’s foot, and a bottom layer opposing the top layer which, when in use, faces away from the sole of a user’s foot and towards the inner sole of a shoe, the top layer and bottom layer being joined so as to define an intermediate volume therebetween, wherein at least a portion of the top layer defining the intermediate volume is formed form a pliable material. The insert further comprises two discrete compartments contained within the intermediate volume, the first compartment housing a first component and the second compartment housing a second component, wherein the interiors of the first and second compartments are sealed from one another by a frangible seal, arranged such that the frangible seal may be broken to allow the first and second components to mix. Upon mixing, the first component and the second component react to form a solidified material.

[0008] The present invention provides a shoe insert which may be easily customized to comfortably fit a user’s foot without the need for any specialist equipment, clinical assistance or long wait times. The process of customising the insert is straightforward, fast and relatively inexpensive in comparison to customization processes of the prior art which require mould-taking and long manufacturing waits. The customisation of inserts of the present invention can be carried out at the time of purchase by the user themselves, to provide a custom shoe insert which is ready to wear in a matter of minutes. The low cost and facile use of the insert allows almost instant access to shoe inserts to minimise discomfort and health implications from wearing ill-fitting shoes for an extended period. The customizable shoe inserts may be used, for example, to improve lower limb pathologies by improving plantar pressure distribution and providing more under-foot cushioning quickly and easily. Better fitting shoes also improve tendency to walk and exercise, helping to treat obesity and related conditions such as type 2 diabetes. The ease of fitting and low cost of the insert allows a user to easily and affordably fit a new pair of inserts to each of a number of pairs of shoes.

[0009] The solidified material formed from the reaction of the two components may be resiliently deformable. Such a material provides the shoe insert with a degree of flexibility to maximise comfort when walking or running with the insert in a shoe by allowing the insert to conform to the movements of the foot and shoe. However, a resiliently deformable material also maintains a degree of rigidity and returns to its original shape after being bent or deformed, to allow constant support to the desired parts of the foot.

[0010] The first component and the second component may expand as they react to form an expanded solidified material. Such expansion causes the reacting mixture of the components to“force” its way around the contours or a user’s foot, filling cavities and enhancing the customisation and fit of the insert. Such expansion may occur, for example, in the formation of a solidified material which is a foam.

[0011] The solidified material may be a foam. Many foams are resiliently deformable, and thus provide the advantages discussed above. Foams are also particularly suited to use in the present invention since they are lightweight, readily available, and are able to provide a cushioning effect underfoot to enhance the comfort of the insert. Many foams will provide an open-pore structure to encourage aeration of the insert, to provide a“breathable” and moisture-wicking shoe insert.

[0012] The first component may comprise a polyol and the second component may comprise a reactive isocyanate. Such materials produce a polyurethane solidified material when they react and are particularly well suited to use in inserts of the present invention due to their ready reactivity and low reaction times (allowing an insert to be customized quickly), and the suitability and comfort of the solidified material for use in shoe inserts. In particular, the solid polyurethane produced may be a foam, which further provides the advantages of foams described above. Polyurethane foams are suitable for use in the insert since they can provide the desired flexibility, compressibility and durability for use in a shoe insert.

[0013] The first and/or second component may comprise one or more further additives selected from the group consisting of chain extenders, catalysts, cross-linkers, surfactants and blowing agents. Such additives allow the customization process and the properties of the insert to be tailored, in particular by adjusting the structure and quality of the solidified material; the time taken for the solidified material to be produced; and/or the foam structure of the produced solidified material where the material is a foam. [0014] In some embodiments, the insert comprises no greater than one first compartment housing the first component and no greater than one second compartment housing the second component. Such an arrangement is advantageous since it minimises the amount of force and the area to which force is required to be applied to break the frangible seal and initiate the hardening of the insert. A user is only required to apply sufficient pressure to a single point to initiate mixing, as opposed to inserts comprising multiple compartments of each component wherein the user must ensure that each individual seal in the insert is provided with sufficient pressure to allow complete breaking and mixing.

[0015] The insert may be dimensioned such that, in use, the insert extends substantially across the whole interior sole of a shoe. In such cases, the insert may comprise:

- an anterior portion which in use is positioned substantially beneath the metatarsal heads and toes of a user;

- a mid-portion which is positioned substantially beneath the arch of the foot of a user; and

- a posterior portion which is positioned substantially beneath the heel of a user.

[0016] Such an insert, which spans substantially the whole interior sole of a shoe, has the advantage that it may be used to customize the entire sole of the shoe. For example, a user may wish to customize the insert to adapt to the shape of the arch of their foot, as well as around the heel and metatarsal heads. Even where solidified material and shape customization is not desired in certain portions of the insert, the insert can still provide other properties to those portions of the foot, for example a cushioning or antimicrobial effect. Additionally, by spanning the sole of the shoe, the insert sits firmly in place and unwanted movement of the insert within the shoe is minimised.

[0017] In such an insert, the first and second compartments may be arranged in the mid- portion; and the insert may comprise an anterior barrier arranged to prevent the first and second components and the mixture thereof from passing into the anterior portion. Such an arrangement allows the advantages associated with an insert which spans the whole sole of the shoe described above to be realised, without allowing the components to leak under the metatarsal heads and toes and form solidified material in an unwanted place. It may be desirable to avoid allowing solidified material to form under the metatarsal heads and toes to maintain a thin forefoot fitting, in order to prevent unwanted reduction of the space inside the toe box of a shoe and to minimise shearing stress on the digits that may otherwise lead to skin irritation and/or blistering, for example on the dorsal aspect of the phalanges.

[0018] Similarly, the insert may additionally or alternatively comprise a posterior barrier arranged to prevent the first and second components and the mixture thereof from passing into the posterior portion of the insert, under and around the heel of the user. Such a barrier may be desirable where additional material is not required in the posterior region and would otherwise compromise the fit and height of the shoe, and to minimise bulk accumulating around the heel which may otherwise be uncomfortable during gait, especially at the heel strike phase.

[0019] Where some customization is required around the anterior or posterior portions, the anterior and posterior barriers may nonetheless still be present to separate portions of reactive components and ensure that excessive amounts of the mixed components do not pool in one portion of the insert without evenly distributing in other portions of the insert. In such cases, further compartments may be present in the anterior or posterior portions, wherein the barrier(s) ensure that a predetermined amount of the reactive components remain in the desired portions.

[0020] The anterior and/or posterior barrier described above may take the form of a seal bonding the top and bottom layers together. Such an arrangement is simple to construct, and is flat, so that the barrier does not add any additional height to the insert to minimise any effect on the height and therefore the fit and comfort of the insert. Where no customisation is required at all in the anterior or posterior regions, the seals between the top and bottom layers may extend across substantially all of the anterior and/or posterior regions, allowing the entirety of those portions to be flat.

[0021] The first and second compartments may be arranged in the mid portion of the insert so as to be positioned in use substantially underneath the inner arch of the foot of a user. When the frangible seal is broken and the components start to mix and react, such an arrangement encourages the solidified material to collect largely in the space formed under the inner arch of the foot. As the inner arch of the foot is prone to discomfort and is a particularly desirable place to provide support, arranging the compartments in such a position enhances the moulding of the insert around that particular portion of the foot.

[0022] The top layer of the insert may comprise a microcellular polyurethane. A particularly suitable microcellular polyurethane is Poron®. The top layer may additionally or alternatively comprise a superficial neoprene layer, i.e. neoprene arranged to be the topmost material on at least a portion of the top layer, and arranged to be in contact with the foot in use. Both microcellular polyurethane and neoprene are particularly suitable for use in inserts of the invention since they are pliable and have high stretching properties, thus allowing a user to manipulate the compartments within to initiate the solidification process, and allowing the insert to expand and conform to the shape of a foot. The materials also provide shock-absorption and cushioning to the foot, enhancing support and comfort when wearing a shoe containing the insert, reducing peak pressure on lower limb joints and providing a bouncing sensation when running. The materials are impervious to atmospheric moisture, preventing moisture from damaging the interior of the insert. The microcellular polyurethane may also be provided with antimicrobial properties, for example Microban® technology, to minimise malodour generated by the foot.

[0023] The bottom layer of the insert may comprise ethyl-vinyl acetate, which is particularly suitable for use in the inserts of the invention since it provides durability to the insert during every day walking and running.

[0024] The frangible seal may be breakable in response to manipulation of the insert to increase pressure in one of the compartments and thus the pressure on the frangible seal from the component contained in that compartment. This construction is simple and user friendly, since the user must only press one compartment and need not be overly precise to initiate the mixing and customisation.

[0025] The frangible seal may be breakable in response to a user placing a foot on the insert. Such an arrangement allows for easy and fast use of the insert since a user may, for example, place the insert into a shoe and initiate the solidification simply by placing their foot in the shoe on top of the insert, at which point the solidification will begin, adapting the insert to the shape of the user’s foot in one step. Breaking the frangible seal by placing a foot on the insert also allows components which react and solidify particularly quickly to be used, since the user’s foot is already in position and there is no time needed to place the insert and the foot in the shoe before solidification can begin.

[0026] According to a second aspect, the present invention provides a method of producing a personalized shoe insert comprising the following steps:

a) providing an insert for a shoe comprising:

a top layer which, when in use, faces the sole of a user’s foot; a bottom layer opposing the top layer which, when in use, faces away from the sole of a user’s foot and towards the inner sole of a shoe, the top layer and bottom layer being joined so as to define an intermediate volume therebetween, wherein at least a portion of the top layer defining the intermediate volume is formed form a pliable material, and wherein the insert further comprises two discrete compartments contained within the intermediate volume, the first compartment housing a first component and the second compartment housing a second component, wherein the interiors of the compartments are sealed from one another by a frangible seal, arranged such that the frangible seal may be broken to allow the first and second components to mix together, and wherein, upon mixing together, the first component and the second component react to form a solidified material;

b) breaking the frangible seal, allowing the first component and the second component to mix together;

c) inserting the insert into a shoe

d) placing a foot in the shoe; and

e) allowing the first component and the second component to react to form a solidified material,

wherein step b) may be: performed before steps c) to e); performed after step c) and before step d); or performed after step c) in response to step d). The insert may be an insert according to the first aspect. By the method of the second aspect a user may benefit from the advantages discussed above in association with the first aspect of the invention.

[0027] Step b) may comprise manipulating the pouch to increase pressure in one of the compartments and thus the pressure on the frangible seal from the component contained in that compartment, such that the frangible seal breaks. Such a method has the advantages as discussed above in relation to the first aspect. [0028] Step b) may be performed before steps c) to e), and the method may further comprise the following step b2) after step b) and before step c):

b2) mixing the first component and the second component by kneading the insert.

[0029] Such a method enhances the mixing of the two components, accelerating the reaction between them and promoting even solidification throughout the insert.

[0030] According to a third aspect, the present invention provides a personalized shoe insert produced by a method of the second aspect.

[0031] According to a fourth aspect, the present invention provides a shoe comprising an insert of the first or third aspects.

Brief Description of the Drawings

[0032] Figure 1 shows a schematic cross section of an insert of an embodiment the invention when placed beneath a user’s foot in an operating configuration.

[0033] Figure 2 shows a schematic plan view of an insert of an embodiment of the invention.

[0034] Figure 3 shows two liquid components separated by a breakable seal.

[0035] Figure 4 shows plantar pressure distribution of a user (a) without using an insert of the invention and (b) using an insert of an embodiment of the invention.

Definitions

[0036] The following are some definitions that may be helpful in understanding the description of the present invention. These are intended as general definitions and should in no way limit the scope of the present invention to those terms alone, but are put forth for a better understanding of the following description.

[0037] Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or" comprising", will be understood to imply the inclusion of a stated step or element or integer or group of steps or elements or integers, but not the exclusion of any other step or element or integer or group of elements or integers. Thus, in the context of this specification, the term "comprising" means "including principally, but not necessarily solely".

[0038] In the context of this specification, the terms "a" and "an" refer to one or to more than one (i.e. to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element.

[0039] In the context of this specification, the term "about" is understood to refer to a range of numbers that a person of skill in the art would consider equivalent to the recited value in the context of achieving the same function or result.

[0040] In the context of this specification, reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

[0041] As used herein, the term "and/or" means "and" or "or" or both.

[0042] In this specification, the terms“insole” and“insert” are used interchangeable to refer to an insert for a shoe.

Detailed Description of the Invention

[0043] An insert 1 for a shoe in accordance with a first embodiment of the invention is shown in cross section in Figure 1 in an operating configuration against a user’s foot. The same insert 1 is shown in plan view in Figure 2. The insert 1 is shown in Figure 2 prior to customisation. The insert 1 comprises a top layer 2 which, when in use, faces the sole of a user’s foot as shown. The top layer is formed of a 2mm thick Poron® 4708 layer 3 with incorporated Microban® technology, overlaid by a 0.5mm stretchable hypoallergenic neoprene layer 4 which is in direct contact with the foot (or sock or other foot covering). Poron® is a microcellular polyurethane. Poron® 4708 (2mm) is a soft cushioning material with a density of 15 pounds per cubic foot; it is firm, energy absorbing, has a high energy return and excellent impact absorption, and is anti-microbial and anti-fungal. Microban® technology is a built-in antimicrobial Poron® property which gives the material an additional level of protection against malodour generated by the foot; the active Microban® ingredient is benzethonium chloride. These layers provide a stretchable, pliable top layer which is able to contour the user’s foot, and a cushioning effect against the user’s foot. The stretchability of the top layer allows for expansion of the components within the insert during customisation.

[0044] The insert 1 further comprises a bottom layer 5 opposing the top layer 2 which faces away from the sole of a user’s foot and towards the inner sole of a shoe when in use; the shoe into which the insert 1 and foot are inserted is not shown in the Figures. The bottom layer 5 is formed from 2mm high-density ethylene vinyl acetate, which provides flexibility and durability to the insert.

[0045] The insert 1 is dimensioned to compliment the size and shape of the sole of a foot and the interior sole of a shoe. The insert 1 comprises an anterior portion 6, positioned substantially beneath the toes and metatarsal heads of a user’s foot; a mid-portion 7 positioned substantially beneath the arch of the foot of a user; and a posterior portion 8, positioned substantially beneath the heel of a user.

[0046] The top layer 2 and bottom layer 5 are joined so as to define an intermediate volume 9 therebetween. The top layer 2 overlaying the intermediate volume 9 is pliable and can adapt to the shape of the foot placed thereon and around the shape of the intermediate volume 9.

[0047] Two discrete compartments are contained within the intermediate volume and shown in magnification in Figure 3. The compartments are arranged in the mid-portion 7 of the insert 1 substantially under the inner arch of the foot of a user, i.e. under the medial longitudinal arch, as shown in Figures 1 and 2. The first compartment 10 houses 26 ml of a first component comprising a polyol, and the second compartment 11 houses 26ml of a second component comprising a reactive polyisocyanate. The first and second components are present in a volume ratio of 1 : 1. In this embodiment, the outer, second compartment 11 extends across approximately ¾ of the width of the medial longitudinal arch. The compartments are in the form of two adjoined burstable pouches. The interiors of the compartments are sealed from one another by a frangible seal 12, which is formed by a micro-lap seal between the walls of the pouches. Before use, the frangible seal 12 maintains the components separate from one another to allow storage and transport of the insert without the solidification reaction occurring prematurely.

[0048] The insert 1 comprises an anterior barrier 13 defining a limit of the intermediate volume 9 and dividing the mid-portion 7 from the anterior portion 6, and a posterior barrier 14 defining an opposing limit of the intermediate volume 9 and dividing the mid-portion 7 from the posterior portion 8. The barriers 13 and 14 and are formed by sealing the bottom layer 5 and the top layer 2 together with an adhesive. The seals extend across the entire anterior 6 and posterior 8 portions, such that those portions lie substantially flat.

[0049] The insert 1 of the embodiment of the Figures further comprises a frangible compartment barrier 15 sealing the interiors of the first and second compartments from the remainder of the intermediate volume 9 (in the mid-portion 7) and arranged such that the frangible compartment barrier 15 also ruptures when the frangible seal 12 between the first compartment 10 and the second compartment 11 is broken, to allow the mixture resulting from the first and second components mixing to expand beyond the original limit of the frangible compartment barrier 15 to other areas of the intermediate volume. In the embodiment of the Figures, the walls of the pouch compartments 10 and 11 which initially contain the components act as the frangible compartment barrier 15; the pouch-like compartments burst (i.e. the wall/compartment barrier 15 ruptures) when pressure is applied to compartments

[0050] In use, the insert 1 of Figure 1 is placed into a shoe such that it lies on the sole of the shoe with the bottom layer 5 against the interior sole of the shoe, and the top layer 2 facing upwards to receive a user’s foot. The user places their foot into the shoe in a usual manner, on top of the insert 1. The weight of the user imparts pressure on the compartments via the user’s foot. The increased pressure of the liquid components inside the compartments imparts perpendicular pressure on the frangible seal 12 and the seal breaks. In addition, pressure is imparted on the walls of the pouch-like compartment and the compartments burst, i.e. the frangible compartment barrier 15 breaks. [0051] Once the frangible seal 12 has broken, the liquid components of the two compartments flow into one another and begin to mix and react. As the polyol and the polyisocyanate of each of the components react to form a solid polyurethane foam, the reacting mixture expands. The shape of the intermediate volume 9 is adapted to the shape the user’s foot by virtue of the pliable top layer 2 covering the intermediate volume 9; the reacting mixture expands to fill the available spaces and voids in the intermediate volume 9 around the contour of the user’s foot, for example the inner arch.

[0052] The expanding foam, as it expands beyond the original limit of the now-broken frangible compartment barrier (the now-burst pouch), expands across the remainder of the intermediate volume between the anterior and posterior barriers. This arrangement maintains the two components in initial close proximity by way of the compartment barrier 15 to encourage thorough initial mixing. The mixture then begins to expand as it reacts and fill the remainder of the intermediate volume, as indicated by the arrow in Figure 2. Maintaining the liquid components in a smaller initial volume also reduces the pressure required to be imposed by the user on the compartments in order to break the frangible seal 12, making initiation of the process easier for the user. The fact that the components are initially contained under the medial longitudinal arch and expand outwards across the insert also allows precise customisation; the solidifying mixture will only extend across the mid-portion as far as allowed by the lateral longitudinal arch of the foot. For example, in a user with a cavus foot type (i.e. arched sole) the solidified material can extend across the whole mid-portion, whereas when used with other foot types the expansion of the material may be limited by the lateral longitudinal arch. The anterior 13 and posterior 14 barriers prevent expansion of the reacting mixture into the anterior 6 or posterior 8 portions, so that the mixture does not expand around the toes, metatarsal heads or heel.

[0053] As the mixture reacts, it begins to solidify and cure as it forms a solidified polyurethane. The solidification takes place within 1 minute, after which the insert is customised to the contours of the user’s foot. If a user removes their foot, the polyurethane foam will maintain the shape of the impression of their foot. The polyurethane produced is resiliently deformable, and so flexes as necessary when walking or running with the insert in position, as well as providing compressibility, whilst still maintaining rigidity and therefore support for the foot as well as durability of the insert. The insert thus provides personalised fitting and support to an off-the-shelf shoe or pair of shoes, wherein the personalisation process can be carried out within minutes and without professional assistance.

[0054] In some embodiments, the shoe insert spans substantially the whole of the interior sole of a shoe. The outer perimeter of the insert may be shaped to compliment the perimeter of the interior sole of a shoe to enhance fitting and coverage of the sole. In some alternative embodiments, the shoe insert is dimensioned so as to sit only on a portion of the interior sole of the shoe, for example under the arch of the foot, under the toes, or under or around the heel. In some embodiments, the insert may comprise an adhesive layer on the bottom layer to adhere the insert to the sole of the shoe, to minimise movement from the desired location. In some embodiments, the insert may comprise peripheral portions which may be trimmed, for example with scissors, to customise the shape and width of the insert so that it fits the desired location, for example so that it fits the perimeter of the interior sole of the shoe. The inserts may be provided in varying pre-determined sizes corresponding, for example, to different shoe sizes or to“small”,“medium” and“large” sizes, and may be provided in different widths, for example to cater for the differing widths between men’s and women’s shoes.

[0055] The“top layer” and“bottom layer” as they are referred to herein may be a single layer of a single material in some embodiments, or they may comprise multiple different layers bonded together in alternative embodiments. For example, a“top layer” may comprise a base layer, a mid-layer (for example to provide a property such as cushioning or shock absorption) and a superficial layer in contact with the foot (for example to provide sweat-wicking or anti-odour properties). For example, the top layer may comprise a polymer base layer, bonded to a layer of microcellular polyurethane as a mid-layer, bonded to a layer of neoprene as a superficial layer at least partially in contact with the foot of a user during use. Each layer may entirely cover the layer beneath it, or a layer may cover only a portion of the layer beneath.

[0056] In some embodiments, the top and bottom layers are joined by sealing the top and bottom layers together, for example by heat sealing. Any other plausible sealing mechanism may be used, for example adhesive or stitching. In some alternative embodiments, the top and bottom layers are joined by virtue of being continuous with one another, i.e. the insert comprises a pouch, the interior of which is the intermediate volume. The top and bottom layers may thus comprise the same material, and they may have one or more further materials overlaid on the“base” material of the pouch. The“bottom layer” of the pouch, i.e. the face of the pouch in contact with the interior sole of the shoe, may be bare or may have one or more further layers overlaid, for example a strengthening layer for durability (for example high density ethyl vinyl acetate) and/or an adhesive layer for bonding to the sole of the shoe. Alternatively or additionally, the“top layer” i.e. the face of the pouch oriented to the sole of the user’s foot in use, may have one or more further layers overlaid, such as a cushioning layer, a shock absorbing layer, an anti-microbial layer, or a layer of a material intended to provide a pleasant sensation against a user’s foot, for example fleece. For example, the top layer may comprise an overlaid layer of microcellular polyurethane, for example Poron®, for example 2mm Poron ® with Microban® technology, for example Poron® 4708 (2mm) and a further superficial layer of neoprene, for example 0.5mm stretchable hypoallergenic neoprene directly facing the user’s foot.

[0057] In some embodiments, the top and/or bottom layers comprise one or more materials selected from the group consisting of: an antimicrobial material, an anti-odour material, a sweat-wicking material, an absorbent material, a cushioning material, a shock absorbing material, a soft material for example fleece, an insulating material, a textured or massaging material, or another material otherwise intended to provide a pleasant sensation or other advantage to the user.

[0058] In some embodiments, only a portion of the top layer defining the intermediate volume is pliable, such that a part of the insert may mould to a contour of at least part of a user’s foot. In some embodiments, the entire top layer is pliable. In some embodiments, the entire insert is formed from pliable materials such that the whole insert may mould to the contours of a user’s foot.

[0059] In some preferred embodiments, the top and/or bottom layers are impervious to moisture.

[0060] In some embodiments, only a single first compartment containing a first component is provided, and only a single second compartment containing a second component is provided. In some embodiments, more than one of each compartment is provided, for example two or three of each compartment. In some embodiments, different portions of the insert are each provided with a first and second compartment; for example, the anterior portion under the toes of a user may be provided with a first and second component, the mid-portion under the arch of the foot may be provided with a further first and second compartment, and the posterior portion under the heel may be provided with a further still first and second compartment.

[0061] The compartments may be formed from one or more separate sub-containers, for example pouches, housed within the intermediate volume. The compartments may alternatively be formed from the intermediate volume and top and bottom layers, wherein the frangible seal divides the intermediate volume into two compartments, and a further seal may optionally form a frangible compartment barrier which partially defines a wall of one or both of the compartments and further divides the intermediate volume into three compartments. The compartments may be independent from the remainder of the insert, i.e. not formed from the top and/or bottom layers, or they may be defined partially by the top or bottom layer, together with an internal sub-layer within the intermediate volume. The compartments may be arranged in manners other than that shown in Figures 1 to 3; for example, either of the compartments may be disposed to the inner or outer aspect of the arch of the foot.

[0062] At least the surfaces defining the intermediate volume, usually the top and bottom layers in the regions defining the intermediate volume, should be impervious to the components contained in the compartments to prevent leakage of the components out of the insert. Preferably the surfaces are also impervious to water to prevent leakage of moisture into the insert which may damage the components or the solidified material. Where the components and solidified material are contained within a separate sub- container within the intermediate volume, for example pouches, those sub -containers may be additionally or alternatively impervious to the components and moisture.

[0063] In some embodiments, the frangible seal sealing the interiors of the compartments from one another is breakable by imparting pressure on one of the compartments. In such embodiments, the increased pressure of the component in the compartment on the frangible seal causes the seal to rupture. In some embodiments, the frangible seal is breakable by applying pressure directly to the seal itself, i.e. not as a consequence of increased pressure in one of the compartments; for example, the seal may comprise a wall or rigid membrane between the compartments which, when pressure is applied to the wall e.g. the user presses down on the seal, breaks and allows the components to mix. In some embodiments, the seal may be breakable by bending or twisting the insert. In some embodiments, the insert may comprise a trigger, such as a button or pull-tab, configured to break the seal when the trigger is activated.

[0064] The frangible seal may comprise a wall or membrane, for example which may be ruptured by increased pressure from one of the components, or which may be broken by pushing on the seal, or bending or twisting the insert. The seal may be a micro-lap seal. The frangible seal between the compartment interiors may alternatively be in the form of a seal which bonds the top and bottom layers together. The seal may be formed by, for example, an adhesive between the layers or by heat-sealing the layers together. Such a seal may be frangible for example by increasing the pressure in one of the compartments to force the layers to separate, or for example by pulling a pull-tab disposed on the exterior of the insert to separate the layers.

[0065] The first and second components are two materials which, when mixed react to form a solid or semi-solid resin or a gel. A“solidified material” in the context of the present specification means that the solid, semi-solid resin or gel is sufficiently solid to maintain its desired shape around the contours of a foot whether the foot is present or not. The components may be solid, liquid or gas, or mixtures or suspensions thereof. The components may comprise for example, two monomers in separate components which react to form a polymer; a composition and a catalyst which causes a solidification reaction; or a polymer and a cross-linking agent. The first and second components may comprise, for example, a polyol and a polyisocyanate. The polyol may be, for example, a polyether polyol or a polyester polyol. The first and second components may comprise a polyol and a reactive isocyanate respectively, and one or both of the first and second components may optionally further comprise a catalyst. In some embodiments, the components may comprise a liquid polyurethane and a solidification catalyst, wherein the reaction is the hardening of the polyurethane to a solid, semi-solid or gel. In some embodiments, one of the components may comprise a polyurethane resin and the other component may comprise a cross-linking agent, wherein the reaction is cross-linking of the polyurethane to produce a solid, semi-solid resin or a gel. Other resins which may be included in one of the compartments include silicone resins, epoxy resins, melamine resins and polyurea resins.

[0066] The first and second components may be present in any suitable volume ratio, depending on the nature of the components chosen and the desired reaction. For example, the volume ratio between the components may be from about 10: 1 to about 1 : 10, for example from about 5: 1 to about 1 :5, for example from about 3: 1 to 1 :3, for example from about 2: 1 to about 1 :2. For example, the components may be present in a ratio of about 1 : 1. In some embodiments, the first and second components may comprise a polyol and a reactive isocyanate respectively and may be present in the insert in a 1 : 1 volume ratio.

[0067] One or both of the components may comprise one or more further additives. Such additives may be included to impart a desired effect on the reaction or final solidified material. For example, an additive may be a catalyst to accelerate the rate of the reaction and time taken to solidity. The additive may be a cross-linking agent or a chain-extender to tailor the degree of solidification and physical properties of the solidified material, for example of a polyurethane. The additive may be a surfactant to enhance the reaction rate and modify the characteristics of the solidified material, for example of a polyurethane foam, by emulsifying liquid components, regulating cell size in a foam, stabilizing the cell structure and preventing collapse of the foam voids. The additive may be a blowing agent to enhance the formation of a foam. Additives may impart a detectable change on the reaction to allow the extent of reaction to be observed, for example an additive may impart a colour change of chemoluminescence (e.g. by mixing of luminal and hydrogen peroxide additives).

[0068] The reaction of the components may be exothermic or endothermic. However, when the reaction is exothermic, the increase in temperature should be within a tolerable range for human skin. For example, the exothermic reaction should not raise the temperature of the insert or a surface thereof to above 90 °C, preferably not above 80 °C, 75°C, 70°C, 65°C or 60°C. Preferably at least the surface of the insert contacting the foot remains at a temperature below 50°C throughout the solidification reaction. Similarly, in cases where the reaction is endothermic, the temperature of at least the surface of the insert in contact with the foot should not be reduced to below 0°C. Preferably the temperature of the surface of the insert in contact with the foot remains above lO°C, for example above 20°C.

[0069] In some embodiments the components may react to solidification in the desired shape and form within 1 hour of mixing, preferably within 45 minutes, within 30 minutes, within 20 minutes, within 15 minutes, within 10 minutes, within 5 minutes, within 3 minutes, or within 2 minutes of mixing. Preferably, the components react to solidification within 2 minutes or within 1 minute of mixing. Mixing may begin as soon as the frangible seal is broken, or, for example, may begin once a user has kneaded the insert to mix the components. The components may react and solidify to their full extent within the time frames described above. Alternatively, the components may react and solidify to an extent sufficient to maintain the desired shape and form within the time frames mentioned above, and they may continue to cure or harden to solidify to their full extent over an extended period.

[0070] In some embodiments, the frangible compartment barrier is not present and the components react and solidify within the volume initially occupied by the compartments, for example the whole of the intermediate volume, the mid portion, or a subsection thereof. In some embodiments, the frangible compartment barrier is a seal, for example a heat seal or an adhesive seal, which bonds the top and bottom layers together, or bond the walls of the compartments together. The frangible compartment barrier may be breakable in the same manner and at the same time as the frangible seal between the compartments is broken; for example the frangible compartment barrier may be breakable by a user standing on the insert and imparting pressure on the frangible compartment barrier via the compressed components, so as to burst the compartments. Alternatively, the frangible compartment barrier may be breakable by the expansion of the reacting components, wherein as the components react and expand, they force the top and bottom layers apart to break the seal; in such an embodiment, the seal may extend across an area into which the solidified material will expand, for example the mid-portion, or it may only separate the volume into which the solidified material will expand from the volume in which the components are initially contained. Alternatively, the compartment barrier may be a wall or membrane (i.e. not a seal bonding two layers together) which separates the volume into which the solidified material will expand from the volume in which the components are initially contained, and which is ruptured by the expanding reacting components or by pressure from the components, for example as a result of a user standing on the insert. For example, the wall or membrane may be a wall of one of the compartments, which ruptures when pressure is applied. In one such embodiment, the compartments may be in the form of pouches which burst upon application of pressure, and the wall of the pouches constitutes the frangible compartment barrier. The frangible compartment barrier may be a micro-lap seal.

[0071] In some embodiments, no anterior or posterior barriers are present and the insert comprises a single open intermediate volume. In some embodiments, only one of the anterior or posterior barriers is present. In some embodiments, the anterior and/or posterior barriers are a seal bonding the top and bottom layers together, for example a heat seal or an adhesive seal. In some embodiments, the anterior and/or posterior barriers are walls or membranes extending between the top and bottom layers. In some embodiments, the anterior or posterior barriers are seals which extend across the entirety of the anterior and posterior portions, such that the insert comprises a single intermediate volume in the mid- portion. In some alternative embodiments, the intermediate volume is instead confined to the anterior portion, or to the posterior portion, for example if customisation is only required in those regions but where it is still desirable to provide an insert of greater surface area to enhance fit of the insert within the shoe or to provide other properties to other parts of the foot, for example cushioning. In some alternative embodiments, the anterior and/or posterior barrier does not extend across the whole of those portions, and instead further compartments are provided in the anterior and/or posterior portions; in such embodiments, the anterior and/or posterior barriers may function to prevent components pooling disproportionately in certain portions of the insert.

[0072] In some embodiments, the components do not expand as they react. In such embodiments, the components mould to the contours of the foot by flowing through the intermediate volume and pooling in cavities formed by the foot. Further barriers may be present to further subdivide the insert, for example to divide left and right portions of the insert.

[0073] In use, the frangible seal may be broken to initiate customisation before placing the insert in the shoe, either by placing a foot on the insert or by otherwise breaking the frangible seal as described above. Alternatively, the frangible seal may be broken once the insert is placed in the shoe, either by placing a foot in the shoe on top of the insert or by manually breaking the seal as described above.

[0074] Once the frangible seal has been broken, the components may be allowed to mix freely. Alternatively, they may be mixed manually by kneading the insert, either before the insert is inserted into the shoe or after it is inserted into the shoe. The insert may be kneaded by hand, or by rocking a foot on top of the insert.

[0075] The insert may be customized by allowing the components to react and solidify whilst in position in a shoe with a user’s foot placed on top of the insert. Alternatively, a user’s foot may be placed on top of an insert and allowed to solidify without first placing the insert in a shoe; the insert can subsequently be placed in the shoe once the insert has been customised to the shape of the foot.

[0076] The insert may be provided alone, either as a single insert or, more commonly, as a pair of inserts. The insert may also be provided in combination with a shoe. The insert may be provided inserted into the shoe by being placed on the surface of the interior sole, or the insert may be enclosed in a compartment within the shoe, either removably or irremovably.

[0077] The insert may be integrated in an item of self-customizable footwear. For example, the“bottom layer” of the insert may be formed from the shoe itself, in which embodiments the top layer of the insert functions as the interior sole of the shoe. The features of the insert described above may be applied to such a shoe mutatis mutandis. The shoe may be customized by the process as described above for the insert mutatis mutandis.

[0078] The insert or shoes described above may be used in the treatment or prevention of lower limb pathologies, improvement of plantar pressure distribution, and in the treatment and prevention of obesity and related conditions such as Type 2 diabetes. The inserts or shoes described above may also be used to enhance the comfort of a shoe, to prevent blisters, or to provide other concurrent effects such as anti-microbial or anti-odour properties, sweat-wicking or insulation.

[0079] This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Examples

[0080] The invention will now be described in more detail, by way of illustration only, with respect to the following examples. The examples are intended to serve to illustrate this invention and should in no way be construed as limiting the generality of the disclosure of the description throughout this specification.

Example 1

[0081] Figure 4 shows the changes in plantar pressure distribution achieved when using an insert of the invention. Figure 4 (a) shows the pressure distribution without an insert, while Figure 4 (b) shoes the pressure distribution with the insert. It can be seen that pressure is greatly reduced in the arch area of the foot. In addition, pressure is reduced underneath the 2 ^nd metatarsal (outlined in a square).

[0082] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications.

[0083] The reference in this specification to any prior publication (or information derived from the prior publication), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from the prior publication) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.