Field of the Invention

The present invention relates to a heater assembly, and specifically one most ideally adapted for vaporising, aerosolising, gasefying or otherwise promoting an amount of a volatile liquid, or some formulation predominantly consisting of such a liquid, into the atmosphere immediately surrounding the heater assembly. More specifically, the present invention may find application in any electrically powered and/or electronically controlled aerosol-generating inhalation device, whereby some formulation, being essentially comprised of a volatile liquid and further including some chemically, therapeutically, pharmaceutically active substance, is firstly aerosolised and subsequently or simultaneously inhaled by a user of the device such that said user receives a prescribed or desired dose of the active substance in broadly identical manner to that in which a smoker of conventional tobacco receives an amount of nicotine. Most specifically therefore, the present invention seeks to provide an entirely novel and somewhat revolutionary heater assembly ideally adapted for use in articles such as electronic cigarettes (commonly now known as "eCigs", "vaping" devices, or more generally Electronic Nicotine Delivery Systems or "ENDS") within which a formulation containing nicotine at a prescribed or desired concentration is aerosolised immediately prior to being inhaled by a user of the device.

In the following description, the skilled reader should understand that any use herein of the terms "aerosolize", "aerosol" or similar cognate expressions is to be interpreted as encompassing any physical process whereby any one or more of: a volatile liquid, some formulation predominantly consisting of such a volatile liquid, any constituent component thereof or diluent substance therein, and possibly any complex derivatives thereof, are forcibly promoted, usually by the application of heat, into the surrounding atmosphere, in any phase, i.e. as a gas, a liquid, or a solid, or any phase intermediate thereof. The meaning of such terms could therefore extend to any one or more of: atomization, vapourisation, gasification, nebulisation, and the respective vapours, aerosols, mists, and the like which are created as a result. Furthermore, the term "vaping" as used herein shall be considered to apply to both to the practise of inhaling aerosols including some pharmaceutically active substance for the purpose of drug delivery, and devices adapted for this purpose, and "vaping", and this application more generally, shall not be considered as being limited solely to the delivery of nicotine, despite the following description being largely focused on devices primarily adapted for the delivery of that particular substance.

Background to the Invention

Vaping as a pursuit has experienced explosive growth over the last few years, and there are already now available a vast array of vaping devices available. The globally widespread adoption of vaping devices does of course fundamentally relate to the desire of most smokers of conventional tobacco products (CTPs) to stop smoking, or at least reduce or eliminate their dependency on nicotine and most vaping devices are sold and used as smoking cessation aids. Notwithstanding this primary purpose, it should be mentioned that such devices are often used as lifestyle accessories and also by previously non smoking individuals. In any event, it is largely beyond doubt that the use of vaping devices is significantly less harmful than the smoking of CTPs. As to the efficacy of vaping devices as regards the delivery of nicotine into the bloodstream of users, it is believed that such devices and the formulations used therein are not quite as effective as the smoking of combustible CTPs, but recent prior art and certain scientific studies have addressed this problem, in particular by modifying either the formulations or the inhaled aerosols such that they contain at least one pharmaceutically salt of nicotine, as opposed to only nicotine. See, for example,

US9215895/Juul Labs Inc., entitled Nicotine Salt Formulations For Aerosol Devices And Methods Thereof,

Nicotine & Tobacco Research, 2018, 458-465, doi:10.1093/ntr/ntx093, entitled "Evaluation of Nicotine Pharmacokinetics and Subjective Effects following Use of a Novel Nicotine Delivery System", Teichert, Brossard, Medlin et ai), and

- WO2017108983, WO2017108987, W02017108991, WO2017108992, all in the name of Philip Morris Products SA, and all of which would appear to cover certain aspects of the vaping device discussed in the abovementioned Scientific Article. These latter four International/PCT patent applications in particular relate to a disposable or refillable cartridge for a vaping device, and the cartridge itself has two compartments disposed on either side of a central slot in which a blade-like heater of the device is received when the cartridge is inserted, connected or otherwise fitted to or within the device. Thus the heater blade, when activated, for example when a user presses a button or switch on the device, transfers heat to both compartments and their contents simultaneously. The device generates an aerosol of desired composition by virtue of the fact that each compartment contains an amount of a carrier material which is impregnated, for one of the compartments, with nicotine, or an aqueous or non-aqueous solution thereof, and for the alternate compartment, with a carboxylic acid, such as lactic acid, or an aqueous or non-aqueous solution thereof, and when sufficient heat is applied to the carrier material, and thus to the substances impregnated therein, they are aerosolised into the surrounding atmosphere. Thus the carrier materials act as reservoirs for the fluids impregnated therein, and the amount of fluid the carrier material can retain is stated as being in the range of 1 -40mg, or 2-60mg, depending which particular liquid they are impregnated with. Of course, as is the case for all vaping devices, a user will typically be causing an airflow through the device while it is activated by mouth-applied suction pressure, so the aerosols created as described are entrained in the respective airflows occurring at that time within and through the compartments of the cartridge. At some stage within either the cartridge or the device itself, these respective airflows unite and are mixed together, and the aerosolised nicotine and acid within each airflow react with one another, ideally in stoichiometric manner, such that the resulting combined airflow contains a desired amount of a nicotine salt immediately prior to being inhaled by the user.

In the context of the present invention, the most important aspect of the above discussed prior art, and more standard conventional prior art devices further discussed below, is the carrier material, and the manner in which it is heated. In the applications discussed above, it is of course necessary that the carrier material is porous to at least some degree, because of the requirement that it be impregnated with one or more liquids or liquid solutions. Ideally, it is stated that the porosity of the carrier materials is between about 15% and about 55%. Furthermore, the carrier materials are described as comprising one or more of: glass, cellulose, ceramic, stainless steel, aluminium, polyethylene (PE), polypropylene, polyethylene terephthalate (PET), poly(cyclohexanedimethylene terephthalate) (PCT), polybutylene terephthalate (PBT), polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), and BAREX< ® >. Most specifically, the carrier materials are described as being non-woven sheets of PET/PBT of suitable size and shape (e.g. 4- 6mm wide, 10-20mm long, and 0.5-2.5mm high) , having a density of 0.1 grams/cubic centimetre and about 0.3 grams/cubic centimetre. The most important aspect of these various disclosures as regards the present invention is that the carrier materials described are essentially lightweight absorbent fabrics capable of holding and retaining much more than their own weight of fluid, and in this regard are essentially no different to the more conventional cotton or polymer fibrous wicks used in more conventional so-called wick- and-coil vaping devices. Indeed the only differences between the device discussed above and the now ubiquitous wick-and-coil vaping devices are:

- the absence of any discrete reservoir for containing a supply of liquid formulation to be aerosolised, and within which a conventional wick-and-coil assembly would be disposed with at least some portion of the wick submerged in the liquid so that, by virtue of capillary action and possibly other physical processes, the wick becomes soaked with the liquid, and

- the fact that the heater blade is not in direct contact with the carrier material, as it is generally in most conventional wick-and-coil devices, but is separated therefrom by the compartment walls which inevitably present a thermal barrier to heat flow from the heater blade disposed therebetween.

The above described device, and wick-and-coil vaping devices in general, both have a variety of fundamental disadvantages, the first and most notable of which is that, for both devices, the heater is essentially a completely separate and discrete component, and therefore its fitting within or to the cartridge or the device is entirely separate and relatively time consuming manufacturing step. Also, the resistive wire(s) or track(s) which constitute the heater can be quite delicate and easily damaged, and it is of course essential for proper functioning that a reliable electrical connection is maintained between the heater and the device battery, and therefore the heater is generally always a permanent and quite protected component of any vaping device, and one which is often manually installed during manufacture. Furthermore, the conventional wicks, or the carrier material in the above described device, are essentially fibrous in nature and therefore highly susceptible to variation in terms of their physical properties, and somewhat difficult to manipulate, at least by automated machinery, as they are effectively quite soft and pliable structures, and the fibres of which they are constituted can very easily be worked loose. This is particularly true for conventional wick-and-coil vaping devices, because wicks used therein are most commonly cylindrical or annular in cross-section, and constituted entirely of many hundreds or thousands of individual elongate fibres of a sorbent material which are compressed together. In most cases, the materials used for creating wicks will either be naturally occurring or created from naturally occurring materials (e.g. cotton and rayon), or the fibres may be entirely chemically synthesised, for example by polymerisation (e.g. nylon, acrylics, polyesters, etc.). In any event, both the sorbency of the materials themselves, and the fact that they are fibrous and can be either compressed or in some cases woven together to create a fibrous mass or fabric which by their nature will possess inherent porosity, and thus have an affinity for liquids which allows them to become easily soaked therewith, have traditionally been important factors in creating useful wicks.

As the skilled reader will appreciate from the above, wick-and-coil devices are essentially quite rudimentary devices, and as such provide very little operative consistency between one activation, i.e. when aerosolisation is occurring, and the next. For example, for conventional wick-and-coil devices, a liquid formulation consisting very simply of only nicotine (usually at a concentration of between about 5 mg/ml and 50mg/ml) and a pharmaceutically acceptable carrier such as polyethylene glycol (PEG), vegetable glycerol (VG), or Propylene Glycol (PG) will be added to a reservoir of the device prior to activation. Once the user activates the device, the heater element rises quickly to a temperature which may be anywehere between 150 deg.C and 270 deg. C (nicotine boils at 247 deg.C), and once the heater reaches a temperature approaching or above the boiling point of the carrier liquid, then at least some aersolisation can begin to occur. However, aerosolisation is an exceedingly complex physio-chemical process, and the quality of aerosolisation as well as the concentrations of constituents in any aerosol produced depends various factors, including the extent to which the wick is soaked with formulation, the heater temperature, and whether the heater is in complete contact with the wick or whether portions of the heater have become separated and to what extent. Importantly, the concentration of nicotine present in any aerosol produced can vary significantly between successive aerosolisations, at least for conventional wick-and-coil vaping devices. For more recent devices, such as described in the abovementioned prior art PCT applications, the dosing consistency is slightly improved, but the heater used is still essentially a simple resistive wire heater prone to hot spots, and the nature of the device is such that the heater must necessarily be entirely separate from the carrier material it is adapted to heat - this is a very inefficient arrangement, and results the device having much shorter active life between battery charges because the heater is required to operate at significantly higher temperatures to ensure rapid aerosolisation, i.e. within 1 -2s of user activation occurring.

It is therefore the primary object of the present invention to address such problems, disadvantages and difficulties, and to provide a novel and revolutionary heater assembly which not only ensures reliable, repeatable and consistent aerosolisation, in particular as regards the concentration of a pharmaceutically active substance within aerosols produced by the said heater assembly, but one which is also relatively much easier to manufacture than existing wick-and-coil heating assemblies, and one which particularly lends itself to entirely automated manufacture without manual involvement.

It is a yet further object of the invention to provide a heater assembly which is inexpensive, and disposable, and which is intrinsically simple and quick to insert within or connect to a suitably designed vaping device in a manner which ensures reliable electrical connections therewith.

Other objects and advantages of the present invention will become apparent from the following description.

Summary of the Invention According to a first aspect of the present invention there is provided a heater assembly comprising a substantially solid, rigid substrate having a body defined by a plurality of exterior surfaces at least one of which is substantially planar, and at least one electrically resistive heater component comprising at least one resistive element portion and at least a pair of contact portions in electrical communication therewith, said heater component being physically secured to or within one or more of the substrate exterior surfaces such that the resistive element portion thereof is substantially disposed on said substantially planar exterior surface of said substrate with at least some part of one surface of said resistive element portion being substantially coplanar with said substantially planar exterior surface, said substrate being formed by sintering a granular or fibrous precursor material in which the average radial dimension of granules or fibres is less than 250pm, and which, after sintering, has a porosity of at least 0.4, and having an absorbency such that the substrate is capable of absorbing a volumetric amount of liquid at least 30% of the volume of the substrate itself,

Characterised in that the substrate is pre-dosed, in that the substrate is substantially saturated with an amount of a formulation containing at least one active composition, being one or more of nicotine, a nicotine salt, nicotine base, or a pharmaceutically active nicotine derivative composition, said active composition being dissolved or mixed with a pharmaceutically acceptable liquid carrier material, the concentration of the active composition in said formulation and one or more of: the dimensions, the porosity, and the absorbency of the substrate being selected so that one substrate is capable of absorbing and retaining, and thus being a self-contained reservoir for, a volumetric amount of formulation containing an amount of active composition which substantially corresponds to the daily nicotine dose of an individual smoker of a conventional tobacco product (CTP) on a multi-use basis.

For the avoidance of doubt, sintering and cognate expressions used herein is to be understood as meaning a process involving at least one of heat and pressure whereby a material, without becoming liquefied, is melded, fused or caused to undergo some other physical or structural change which results in the solidification of an initially granular, particulate or fibrous mass. As such, an amount of an initially loose precursor material becomes essentially bound together by and within itself in a manner which gives rise to significantly enhanced porosity as compared to that initially solid mass of the precursor material, which in most cases would have negligible porosity. Applicants herefor have advantageously discovered that using a sintered material for the su bstrate of the heater assembly allows an essentially solid component to function with at least equal if not actually improved wicking characteristics as compared to conventional fibrous wicks, while offering the further advantage that such solid components can not only be manipulated far more readily and in automated manner than a collection of fibres, whether only loosely held together in clumps or even when woven together as a soft fabric. Importantly, the act of sintering causes a change in the manner in which the precursor material is bonded together at the atomic level, whereas in fibrous masses and woven and non-woven fabrics, there is no such change and therefore any component formed purely therefrom will always possess some degree of inherent softness, rendering it practically impossible to reliably, precisely and uniformly apply anything, whether in liquid or solid form, to the exterior surfaces thereof. By contrast, sintered products and components are solid, and therefore the exterior surfaces thereof can be printed, coated, embossed, and indeed be subjected to a wide variety of surface treatments, including, most particularly, the surface application, mounting and bonding of secondary components, such as resistive heating elements.

It is also to be mentioned that the pore size, which can be an important factor as regards the ease with which fluid can flow within, and be retained by the substrate, can be altered selectively, for example by adjusting the sintering process parameters, for example temperature or pressure, as will be understood by those skilled in the art. Indeed, it is known that for certain materials, the pore size within the sintered article may be dependent on, and capable of being adjusted by, firing the sintered article at different temperatures after sintering.

Thus, as th4e skilled person will readily understand, the present invention effectively provides a disposable, multi-use, daily cartridge which is specifically designed for particular types of smoker, and which is further specifically designed to be largely exhausted at the end of a single day's use in a conventional vaping device. More specifically, after the pre dosed substrate is inserted in a conventional vaping device, for example at the beginning of a day, a conventional smoker will then use that device and the pre-dosed substrate within it to produce a nicotine- or nicotine-salt-bearing aerosol for inhalation, multiple times during that day. Most preferably, the design of the substrate and the relative concentration of active composition within the initial volume of formulation which the substrate retains takes into account the number of times that the said particular type of smoker would, according to his habit, be likely to use his vaping device. For example, a relatively light smoker who smokes 5 relatively mild cigarettes over the course of a single day may undertake a total of 30 inhalations (and corresponding hand-to-mouth gestures) in a single day. This number is a fundamental design parameter, as is the approximated amount of nicotine which would be delivered to that smoker as a result of his/her consuming that number of cigarettes of that strength, in terms of nicotine content. The present invention can thus provide a custom-tailored smoking cessation aid, as the substrate of the present invention, when used in an appropriate vaping device, would deliver multiple discrete aerosols laden with appropriate amounts of said active composition to said smoker. Furthermore, by provide a custom-designed pre-dosed substrate in this way, not only would the substrate would be largely exhausted at the end of said one day, under habitual use conditions, but the smoker's nicotine requirement, as a result of his dependency thereon, would be substantially if not entirely sated.

Preferably, the pore size within the sintered substrate is in the region of 25-170pm, and most preferably between 30-100 pm.

In certain embodiments, the heating component is directly printed, for example by screen printing, lithography, or a gravure printing technique, on the substantially planar exterior surface of the substrate, said printing including the use of an electrical ly conducting printing ink. In other embodiments, the heating component is an entirely separate article, for example a conducting foil in having a predetermined pattern in which are defined resistive heating element and (separate and distinct) contact portions, and which is bonded to the exterior substantially planar surface of the substrate, by any one or more of: adhesive, pressure, heat, light (e.g. by laser), ultrasound. In the preferred case where an adhesive is used, critically the adhesive must (a) be capable of withstanding the operating temperature range of the heating element when in use (e.g. 100 deg.C to 200-250 deg.C), and (b) the adhesive layer which bonds heater component to substrate is of a pattern which is substantially identical to the shape and configuration of the heater component so that other areas of the exterior substantially planar surface of the substrate remain essentially uncovered, free of both adhesive the heater component. The reasons for this will become clear from the further description provided below.

In other embodiments, the heater component may be formed in place on the at least one exterior substantially planar surface of the substrate, for example by firstly applying one or more uniform layers of one or more substances, at least one of which is electrically conducting, for example by printing, coating, dipping, or a more precise chemical deposition technique, and then subsequently performing a selective removal technique, such as etching, ablation, whether by laser or chemically, photolithography and photoengraving, such that what remains on the relevant substrate surface is a desired pattern of an electrically conducting substance.

In a particularly preferred embodiment, an initially separate heater component, for example consisting of a flat or flattened electrically conducting element having contact portions at either end thereof is disposed on top of the initially granular or fibrous precursor material prior to sintering, which thus results in said heater component being partially embedded within one substantially planar surface of the sintered porous substrate. In some embodiments, as the skilled person will appreciate, one or more further heater components may be embedded in different, possibly opposing, surfaces of the resulting sintered substrate, if desired. In most preferred embodiments, the sintering of the initially granular or fibrous precursor material is conducted with the said one or more heater components already in place within the sintering mould or other receptacle within which the sintering is carried out.

Most preferably, the sintering mould or receptacle defines an essentially cuboid, trapezoidal or parallelepiped-shaped interior such that the resulting sintered substrate is correspondingly shaped, and the disposition of the one or more heater components within the resulting sintered substrate is such that a substantially flat resistive element portion of the heater component, constituting by far the majority of the heater component as a whole, is partially embedded within one of a pair of the largest substantially flat surfaces of the sintered substrate, whereas end or contact portions of the heater component, usually being integrally formed with the resistive element portion therof and provided at each opposing terminal end thereof, are disposed on and preferably also partially embedded within either one substantially planar smaller surface of the substrate body so that the contacts portions are disposed separate from but adjacent one another on and partially within that surface, or alternately, with each one of the two contact portions being disposed on and preferably also partially embedded within different, preferably oppositely disposed, smaller, substantially planar surfaces of the substrate body so that the two contact portions each lie on opposite sides of the substrate body. This particular arrangement is particularly advantageous because, when the substrate functions as a pre-dosed cartridge to be inserted within a suitably configured aperture, slot, opening or other appropriate recess within a vaping device adapted to receive such a cartridge, it is generally much simple r, both from a design perspective and an efficacy perspective, not only to create corresponding electrical contacts within the vaping device which come into contact with the corresponding contact portions provided on the sides of the substrate body, but also to provide aerosolization chambers within the vaping device which lie above and/or below the largest surfaces of the substrate body, and those over which the resistive element portions of the heater component are substantially disposed. As the skilled person will appreciate, it is of course sensible that the largest surfaces of an essentially cuboid substrate be those from and through which the majority of the aerosols being formed beneath and on the said surfaces permeate, because the volume of aerosol produced is directly dependent on the surface area from which that aerosol emanates. However, what is not immediately obvious is that by providing the heater component contact portions on one or more of the smaller side surfaces of the substrate, not only can a reliable electrical connection be ensured, but also, such electrical connection, and indeed the contacts themselves, need not, and most preferably do not, interfere with the aerosolization, which occurs most preferably only on or more of the largest surfaces of the substrate. In most preferred embodiments therefore, the terminal contact portions provided at the ends of the resistive element portion are either formed of a conductive material (as opposed to a resistive one), or are alternatively significantly, e.g. by one or two orders of magnitude, more conductive than the resistive element portion of the heater component. Preferably, the precursor material is a polymer and selected from the group comprising: polyethylene (PE), polyamide (PA), polyphenylene sulphide (PPS), any liquid crystal polymers (LCP), polypropylene, polyethylene terephthalate (PET), poly(cyclohexanedimethylene terephthalate) (PCT), polybutylene terephthalate (PBT), polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), or a ceramic (including glasses or glass-like ceramics), in one of fibrous, granular, particulate, or powdered, form.

In particularly preferred embodiments, and to enhance the thermal conductivity of the resulting sintered substrate in instances where the predominant precursor polymer material is not intrinsically thermally conducting (i.e. has a thermal conductivity less than 0.6 W/mK), the precursor material preferably includes an amount of a thermal conductivity enhancing substance, in particulate form, most preferably in nanoparticulate form (particle size < 100nm). For example, the precursor material may contain an amount, preferably evenly mixed throughout said precursor material, of a thermally conducting metal or alloy thereof, for example Aluminium, Titanium, Copper, Silver, Manganese, Zinc, Cobalt, Molybdenum, Iron/Steel, Bronze, Brass, Nickel, or any oxide of such metals, for example AI2O3 and/or TiC>2. Yet further preferably, the thermal conductivity enhancing substance is at most one half, and further preferably at most one third, and most preferably at most one fifth of the electrical conductivity of Silver (6.30x10 ⁷ S/m at 293K) such that the presence of the thermal conductivity enhancing material does not, to any material extent, cause the substrate material to become electrically conductive. In preferred embodiments, the concentration, by volume, of any thermal conductivity enhancing substance added to and mixed with the precursor material is in the range 5-15% by total volume, more preferably 7-10%, and further preferably less than 8%.

Most preferably, the sintered substrate has a thermal conductivity of at least 0.6 W/mK at 293K. More preferably, the sintered substrate thermal conductivity is at least 1 W/mK, and yet further preferably the thermal conductivity of the sintered substrate is in the range 1 - 10W/mK. Preferably, the porosity of the substrate is in the range 0.45-0.8, more preferably in the range 0.6-0.8, and most preferably in the range 0.65-0.75.

Preferably, the precursor material is essentially dielectric or otherwise substantially completely electrically insulating and thus non-conducting. Most preferably, the electrical conductivity of the precursor material is at least one, and preferably 2 orders of magnitude less than the conductivity of the resistive heater element portion of the heater component.

As briefly mentioned above, applicants herefor have found that substrate components having such increased porosity levels can advantageously have very significant wicking characteristics, and in particular, the simple dipping of substrates according to the invention in standard nicotine-containing formulations can result in rapid substantially complete saturation of the substrate component. Furthermore, when the heater assembly is active and the heater element directly (and, importantly, predominantly thermally conductively) heats the saturated substrate, one or both of the following can occur:

- the rate of loss of formulation from the exterior planar surface of the substrate as a result of aerosolisation can be offset, at least to some extent by the rate of internal flow within the body of the substrate as a result of its porosity and wicking characteristics, and

- after any single aerosolisation, the formulation can quickly (i.e. well before any subsequent aerosolisation, e.g. < 1 -2s) flow internally within the substrate from regions of the substrate which are relatively saturated with formulation to regions which are relatively depleted, in particular such regions as are most proximate, i.e. above or below, the heater element(s) which have become depleted as a result of the aerosolisation caused thereby. To explain such replenishment features further, the internal flow rate of formulation within the substrate is fundamentally dependent on, among other factors (including gravity), both its porosity and wicking characteristics (which can, individually or in combination, and in some preferred embodiments, outweigh gravitational effects), and the constituent composition of the formulation, in particular the viscosity thereof. Applicants for the present invention have realised that modern formulations are relatively viscous fluids, and meniscal and other surface tension effects of such fluids lend themselves very well to being contained within a sintered porous body having the characteristics as already mentioned, and further described below. Thus while a sintered substrate can become saturated with, for example, a typical VG, PG, PEG + nicotine/nicotine salt formulation, and that formulation can flow within such a substrate, the formlation is nevertheless prevented from escaping from the substrate by virtue of its own viscosity, and other meniscal and surface tension effects - thus, the sintered substrate can function as its own reservoir.

As regards the internal flow rate of formulation within the substrate, this can be readily calculated, or at least quite accurately estimated. Similarly, the rate of loss of formulation as a result of aerosolisation (and possibly also evaporation, although this will always be significantly smaller) is also relatively straightforward to calculate, estimate, or experimentally measure. Therefore, as the skilled person will readily understand, it is possible to design a substrate of suitable dimensions (e.g. if the substrate is of cuboid shape, preferably 5-25mm wide, 0.4-3.5 mm thick, and 5-50mm long) having sufficient porosity, suitable for a particular nicotine- or nicotine-salt-containing formulation, such that, during aerosolisation wherein formulation extant in the substrate in regions thereof immediately proximate, adjacent or at least in the vicinity of the heater element is promoted into the surrounding atmosphere, formulation extant in other more distant regions of the substrate can flow or "wick" into those regions rendered somewhat drier by aerosolisation, and either at a specific desired speed, or at least sufficiently quickly. Hence the distribution of the formulation within the substrate can be regarded as being in a state of equilibrium, and after (and indeed during) any single aerosolization, whereby an amount of formulation formerly present in the substrate is lost to the surrounding atmosphere and the volumetric quantity of formulation remaining within the substrate is correspondingly reduced, the porosity and wicking characteristics of substrate are such that the distribution of formulation within the substrate largely if not completely equalises throughout the substrate, and furthermore sufficiently quickly, i.e. within 1 -2s and before any subsequent aerosolization is likely to commence.

As the skilled reader will of course appreciate from the above, the volumetric amount of formulation remaining in the substrate decreases with every aerosolization, and therefore (because the substrate effectively also functions the reservoir), not only is the formulation progressively depleted from the substrate, but also, and notably quite advantageously, the volume of aerosol produced by successive aerosolisations progressively reduces, as of course does the amount of any pharmaceutical or medically active composition present in the formulation). Thus, the present invention provides a restricted multi-use, disposable, self-contained component which simultaneously functions as a heater, a wick and a reservoir, and which automatically reduces the amount of any pharmaceutically or medically active composition present in the formulation between successive aerosolisations.

Additionally of course, it would be possible to design the heater element(s) with specific thermal transfer characteristics such that the rate of aerosolisation caused thereby was at least appropriately controlled, or most preferably matched to the rate of equalisation of the distribution of the formulation within and throughout the substrate, as this would preclude the creation of substantially or completely dry regions within the substrate immediately adjacent or in the vicinity of the heater elements during or immediately after any single aerosolization has occurred.

Preferably, the sintered solid substrate is one of: rigid, semi-rigid, and flexible. Most preferably, the sintered solid substrate is substantially rigid. In some preferred embodiments, a doping composition applied to one or more surfaces of the substrate, said doping composition possessing at least one physical or chemical characteristic which is incompatible with a corresponding physical or chemical characteristic of said formulation, such that doping composition and formulation are inherently phobic. For example, and most preferably, the doping composition may be hydrophobic, and the formulation may be aqueous or hydrophilic. Alternatively, one of the doping composition and the formulation may be polar, and the other non -polar. Persons skilled in the art will understand that a wide variety of physical and/or chemical properties and characteristics may be contemplated, but in all cases their presence or absence in one or other of the doping composition and the formulation shou ld be such that one should be relatively repellent as regards the other. Preferably the doping composition is one which penetrates the particular surface to which it is applied such that said one or more surfaces become impregnated therewith, preferably to a depth of < 1 mm, more preferably 0.5mm or less, most preferably 0.1 -0.5mm, and yet further preferably between 25pm and 100pm.

Preferably the doping composition is applied to the one or more surfaces of the substrate either uniformly over the entirety of any surface, non-uniformly in that the composition is applied only to particular areas of any surface and not to others, or the amount of hydrophobic composition applied to the said one or more surfaces varies over the surface. Most preferably, the hydrophobic composition is applied to any one or more surfaces of the substrate in patterned fashion.

Thus, by doping certain surfaces of the inherently absorbent and porous substrate, especially one which is essentially cuboid in shape, it can be possible to both

- ensure that any formulation, whether aqueous or otherwise, with which the substrate is impregnated or soaked can escape from only relatively few of the substrate exterior surfaces, preferably only one surface and further preferably only a portion thereof, that being the exterior substantially planar surface to and over which the heating element is bondingly mounted, and on and from which aerosolisation will thus occur, and

- at least partially constrain formulation extant within the substrate, and the flow thereof, such that it occupies, and can flow between, only particular internal regions thereof, such being defined at least partially by doped regions thereof.

In a particularly preferred embodiment where contact portions and the resistive element portion of the heater are provided on different surfaces of the substrate, it may be desirable to dope the one or more smaller surfaces of the sintered substrate on which the contact portions of the heater component are disposed, while of course retaining the largest one or more surfaces of the substrate on which the resistive element of the heater component is/are disposed substantially or comparatively undoped.

As the skilled reader will further appreciate from the above, it is thus possible to limit or prevent the escape of any aqueous formulation, whether during aerosolisation or otherwise, from one or more surfaces of the substrate, or portions thereof, by uniformly coating such surfaces with a doping composition. Furthermore, it may also be possible to define flow pathway regions, reservoir regions and the like within the interior of the substrate by doping exterior surfaces of the substrate to different extents. Thus on one hand, a doped substrate is significantly more efficient, and possesses much improved directionality as regards aerosolization and the subsequent flow of formulation within and through the substrate, and on the other, it particular preferred embodiments when reservoir regions and flow pathways are defined internally of the substrate, it can be possible to restrict the flow rate of formulation within the substrate while aerosolisation is occurring, should this be desirable. Of course, as mentioned above, flow of formulation within the substrate will naturally occur, as a result of the relative high porosity and wicking characteristics of the substrate material, from wetter or soaked regions within the substrate to relatively drier regions and the distribution of formulation within the substrate will thus tend to become equaslised, but a substrate which possess one or more edge regions which are doped can better constrain this physical process, directionally and possibly also quantitatively.

In one preferred embodiment, the doping composition is applied over the exterior planar surface of the substrate in regions outwith those regions occupied by the one or more element portions of the heater component, such that during aerosolisation of formulation extant within the substrate, the aerosol produced thereby is constrained to emerge from the exterior planar surface of the substrate only in the regions thereof occupied by said element portion of the heater component. Alternately, and oppositely, the doping composition may be applied precisely in regions which directly coincide with the heater element portions so that the aerosol produced when the heater elements are active is constrained to emerge only from regions of the substrate lying on to one or other side of the individual heater element portions of the heater.

In the most preferred arrangement, wherein the heater element portion substantially covers the exterior substantially planar surface of the substrate, and this particular surface is arranged so that it is horizontal and thus faces directly upwards or downwards during aerosolisation, any formulation extant within the substrate can then either percolate upwards or downwards within the body of the substrate, in some embodiments at a suitable, appropriate or desired rate, so as to mitigate against the situation where all the formulation within the substrate immediately below (or above) the heater element has been depleted and that region of the substrate is therefore is effectively dry and no formulation exists in that region which can be aerosolised. In the case where the exterior substantially planar surface of the substrate (to which the heater element is bonded) is arranged downwardly during aerosolisation, then the inherent wicking of the substrate would of course be advantageously assisted by gravity.

In a most preferred embodiment, the substrate is essentially cuboid in shape, and its dimensions are selected so that it is capable of absorbing and retaining a predetermined amount of a nicotine containing formulation, most preferably an amount thereof in the range of 15mg to 100mg, further preferably in the range 20mg-80mg, and further preferably in the range 25mg-45mg. Preferably, the nicotine-containing formulation comprises propylene glycol (PG) and one of: nicotine, nicotine base, and a pharmaceutically acceptable nicotine salt such that the concentration of nicotine and/or nicotine salt, in weight-by-weight % terms, is between 10-60%, further preferably 15-55%, and most preferably 40-50%. In a most ideal embodiment, the dimensions of the substrate are about 5mm wide, about 1.5mm thick, and about 15mm long, and one of the pair of largest surfaces (a rectangle of about 5mm by 15mm) is that to, over or within which the heater component, or at least the resistive element portion thereof, is bondingly applied or otherwise secured. In this particular case the total volume of the substrate would be 1 12.5mm ³ , and with a preferred porosity of the substrate material of 0.4-0.5, the total theoretical maximum volume of liquid formulation retainable would be, e.g. 0.4 x 1 12.5mm ³ = 45mm ³ , and with an approximate density of the formulation of 1 g/cm ³ , this amounts to a theoretical maximum mass of formulation of 45mg. In practice, however, this theoretical maximum cannot be achieved, and a more realistic practical achievable amount of formulation which is absorbed into a substrate of these dimensions is of the order of 30- 35mg, of which (most preferably) nicotine (or other active ingredient) would constitute 15- 17.5mg, i.e. about 50% of the weight.

To provide some context as regards the smoking of CTPs, and in particular cigarettes, one cigarette may typically contain approximately 8-20mg of nicotine depending on their strength, but only approximately 5-10% of the total nicotine present actually enters the bloodstream of a cigarette smoker through inhalation. The remaining amount is either lost to the atmosphere as the cigarette burns, decomposes or is pyrolised within the burning end of the cigarette, or is simply exhaled after any inhalation. Therefore, a total amount of nicotine per cigarette smoked may only be of the order of 0.5mg, and totalling to 10mg for a 20-a-day smoker.

Thus from the above, the skilled reader will understand that the present invention is quite radically different from the conventional wick-and-coil vaping devices, which incorporate substantial reservoirs capable of easily containing 2-5mL of formulation, approximately equivalent to 2-5g, and which include relatively much higher rated heater elements capable of aerosolising comparatively much larger quantities of formulation when activated. In terms of the amount of nicotine present in most currently available liquid formulatio ns, this is often in the region of 6-18mg/mL (in weight-by-weight % terms, only 0.6-1.8%), so only a relatively very small amount, e.g. apprx. 20-50mg, of nicotine is present, with the vast majority of the formulation being constituted of the aerosolisable liquid, PG. Thus, and as the skilled reader will be aware, users of conventional devices can often be seen exhaling voluminous plumes of smoke, constituted almost entirely of aerosolised PG, only 0.6-1.8% of which will be constituted of nicotine. By contrast, the substrate of the present invention is relatively much smaller and can only absorb, depending on physical dimensions, only of the order of 30-50pL of formulation (apprx. 30-50mg), in which will be provided a relatively much greater concentration of nicotine, e.g. 15-25mg. Thus, when aerosolisation of such a formulation within the substrate of the present invention is caused to occur, the amount of PG which is aerosolised is significantly less, so much so in fact that there is practically no evidence, in terms of plumes of smoke generated, that any aerosolisation has occurred. Notwithstanding this fact, the nicotine concentration within each aerosol so generated is still sufficient to provide an equivalent effect to a single inhalation of smoke generated from a single puff on a conventional cigarette, e.g. 0.04- 0.05mg nicotine per inhalation, or 0.4-0.5mg per dose, where this "dose" is equivalent to the 8-10 aerosol inhalations commonly undertaken if the vaping device is used instead of smoking of that single cigarette. Also, from the above, it can be seen that the substrate of the present invention is capable of being, and is most preferably, overloaded with an excess of formulation, preferably in one of the ranges: 2-10%, 5-20%, 8-30%, 10-40%, 15-50%, 20-60% as compared to what would theoretically be required by a smoker who conventionally consumed 20 cigarettes a day, and thus had a minimum requirement over that period for an amount of at least 10mg of nicotine, delivered in 20 doses of 0.5mg. Thus the substrate of the present invention is designed to absorb e.g., a 20-60% excess of the amount of nicotine-containing formulation that is required, and therefore, particularly if the substrate is required to be discarded after having delivered 20 doses, there is very little likelihood that the substrate will ever be depleted of formulation to such an extent that it ever remotely approaches a state where it is completely "dry".

Thus, in it's most preferred arrangement, the heater assembly of the present invention is pre-dosed, for example by being submerged in and thus soaked with a nicotine-containing formulation, with an amount of formulation which would provide an amount of nicotine, were all the formulation aerosolised and inhaled, 20-60% in excess of that which would be theoretically consumed by a 20-a-day smoker of medium strength cigarettes (e.g. 8-12mg nicotine per cigarette). Of course, the substrate may be dimensioned differently, and the concentration of formulation correspondingly modified, to accommodate the needs of heavier or lighter users of cigarettes or other conventional tobacco products. Most preferably and advantageously the substrate dimensions and the relative concentration of nicotine in the formulation with which the appropriately sized substrate is initially substantially saturated and thus contains, are carefully selected so that the total amount of nicotine initially present in the substrate is slightly in excess of that required by any type of smoker, of any type of tobacco product, over the course of one single day or 24 hour period. The skilled reader will immediately understand the benefits of this type of dosing, and the possibly marketing benefits of being able to provide, for example, a dedicated "one-day", multi-use component for a smoker who habitually smokes, for example, only 10 mild (i.e. containing only a relatively low amount of nicotine) cigarettes per day, and one for a different type of smoker, for example one who only smokes two relatively higher strength cigars in the evening. It is generally understood in the art, at least as far as conventional wick-and-coil devices are concerned, that it is very important that vaping devices never run dry, i.e. the device should not be activated when either their reservoirs are empty, or the amount of formulation therein is so minimal that the wick is not completely soaked. In either case, the wicks may contain dry spots which, being fibrous in nature, can decompose very rapidly and possibly even begin to combust if heated directly by the resistive coil heating element, leading to an immediately recognisable and exceedingly unpleasant taste in the aerosol created, if subsequently inhaled. The present invention, by contrast, overcomes this well known, so-called "dry burn" situation. Firstly, even if the substrate of the present invention is over-used such that there is little or no formulation remaining within the substrate, then, very simply, there is nothing which can be aerosolised, and nothing is produced. The relatively much lower rating of the heater element employed (typically only rising to temperatures of 120-160 deg. C, as opposed to the 200 deg. C or more to which heater coils in conventional wick-and-coil devices are heated), and the fact that the substrate is a solid material which is much less prone to combustion or even any heat-based decomposition of any kind, and therefore significantly more temperature resistant than conventional fibrous wicks, are contributing factors to this improvement. Of course, as the skilled reader will immediately understand, it is desirable that any vaping device in which the heater assembly of the present invention is to be used would ideally include appropriate control electronics which could indicate to the user when the heater assembly was nearing depletion, or had been used to deliver 20 doses or so (or more or less, depending on the "rating" of the cartridge and whether the smoker makes heavy or light use thereof), so that it could be replaced afresh.

In a some embodiments, the heater component is applied entirely to and over one exterior substantially planar surface of the substrate, and in other preferred embodiments, the heater component is applied to the substrate such that the resistive element portion thereof is applied over and bonded to the said exterior substantially planar surface, and one or more or all of the contact portions thereof are applied over and bonded to one or more substantially planar edges surfaces disposed substantially perpendicularly to the said exterior substantially planar first surface. Thus in this arrangement, the contact portions are provided on an edge surface, and only the resistive heating element portion of the heater component is applied to, and thus acts on the larger first surface. In a most preferred arrangement, the heater assembly comprises two heater components, and the substrate is essentially cuboid in shape such that there are defined therein relatively larger upper and lower exterior substantially planar surfaces to and over which a respective one of the heater components, or the resistive element heating portions thereof can be bondingly applied. In preferred arrangements wherein only the resistive heater element portions are applied to and over the upper and lower larger surfaces, the respective contact portions of the respective heater components would ideally be bondingly applied to and over either: one the same edge surface, or oppositely disposed side or edge surfaces, of the substrate.

Most preferably, the or each resistive heating element portion of the heater component consists of a single track, conductor, or wire which meanders back-and-forth substantially uniformly over and within a discrete area within which adjacent elements thereof are substantially evenly spaced, such that the overall heating effected provided thereby is substantially uniform within that particular area.

In second aspect of the present invention, there is provided heater assembly comprising a substantially rigid substrate having a body defined by a plurality of exterior surfaces at least one of which is substantially planar,

Characterised in that the substrate is formed by sintering a granular or fibrous dielectric or otherwise electrically insulating precursor material in which the average radial dimension of granules or fibres is less than 250pm, and within which there is disposed, prior to sintering, a heating component comprising at least one resistive element portion disposed entirely within said precursor material remote from any exterior surfaces thereof, and at least a pair of contact portions in electrical communication with said resistive element portion and which are disposed exactly at one or a pair of sides of the precursor material prior to sintering such that, after sintering, the heater component is essentially embedded within an essentially solid, rigid substrate body except for said pair of contact portions, and further characterised in that the porosity of the substrate is at least 0.4.

This second aspect of the invention is particularly advantageous because embedding a suitable heater component within the precursor material prior to sintering eliminates the requirement for later application of a heater component. In the most preferred arrangement when the heater component is essentially flat (i.e. the depth of the electrically resistive element portions at least are very much less than their width, typically 1 -2 orders of magnitude less), heat generated can be conducted very efficiently to the surrounding sintered substrate material, and effectively twice as efficiently as the heater component of the first aspect of the invention, which of course is only capable of directly applying heat to the substrate in one direction, i.e. directly to and through the surface to which it is bondingly applied. Of course, in the first aspect of the invention, it may be possible to provide a second heater on an opposite exterior substantially planar surface of the substrate so that it was effectively sandwiched between two heaters, the above second aspect of the invention is always going to be a more efficient arrangement.

In a third aspect of the invention, there is provided a disposable heating assembly as previously described and which has been pre-dosed with an amount of an aerosolisable formulation containing an amount of a therapeutically or pharmaceutically effective medicament at a prescribed concentration and which is adapted for use in a aerosolising device, and which is, preferably, provided within an initially sea led package, wrapper, or container, and within which the atmosphere has either been substantially withdrawn by means of vacuum pressure, or has been substantially displaced with a non-toxic inert gas or one which has preservative qualities as regards the formulation, for example a Noble gas or Nitrogen.

For the avoidance of doubt, any one or more or and all the preferred features of the first aspect may apply equally and be considered as dependent to, subsequent aspects of the invention. It is merely in the interests of brevity that they are not repeated here.

A specific embodiment of the invention is now described by way of example and with reference to the accompanying drawings wherein:

Brief Description of the Drawings Figure 1 shows an exploded perspective view of a mouthpiece and cartomizer (a conflation of the words cartridge and atomizer) assembly, of prior art construction,

Figure 2 shows a plan view of a heater assembly according to a first aspect of the present invention, including a sintered substrate having a heating component printed, embedded within, bonded or otherwise applied to an upper planar surface thereof,

Figure 3 shows a schematic perspective view of the heater assembly of Figure 2, including representative dimensions, and in which the heater component is schematically illustrated,

Figure 3A shows a perspective view of an alternative embodiment of a heater assembly according to the present invention,

Figures 4, 5 show a perspective views of heater assemblies according to further alternative embodiments of the present invention, wherein the heater component is substantially entirely embedded within the substrate, and

Figure 6 shows a side elevation of a yet further modified embodiment of the present invention wherein a heater assembly comprising a substrate and a heater component further comprises a reservoir component.

Detailed Description

Referring firstly to Figure 1, there is shown an exploded perspective view of a prior art mouthpiece and cartomizer assembly 2, in particular a cartomizer forming part of a prior art vaping device sold under the trade name "SMOK®" and manufactured by Shenzhen IVPS Technology Co. Ltd.

Cartomizer 2 consists of a cylindrical cartridge 4 within which a cylindrical wick and coil arrangement 4A, 4B, 4C is centrally disposed. In place, coil 4B is wound internally of the annular wick 4A so that its coils contact the interior cylindrical surface thereof, and one free contact end 4B-1 of the coil is maintained in electrical contact with an end plug 4C behind which the wick-and-coil arrangement is disposed within cartridge 4 when assembled. The end of the coil remote from electrically conducting plug 4C passes over the top of the wick (not as shown in the figure but when assembled) and passes down the exterior cylindrical surface of the wick, ultimately terminating at free contact end 4B-2. Contact ends 4B-1 and 4B-2 are electrically isolated from one another by means of a flexible rubber insulating ferrule (not shown), and the assembled arrangement is such that the electrically conducting plug 4C is of one polarity, and the cartridge itself is of opposite polarity, and no part of the coil comes into contact with any other part so there is no likelihood of any short circuit arising.

Once the wick-and-coil assembly has been assembled, it is inserted within the cartridge 4 in a hollow cylindrical interior defined internally thereof and which is open at first and second ends 6, 8. The cylindrical cartridge 4 is provided with a plurality of axial slots, two of which are referenced at 10, 12 and it is by means of such slots that exterior surfaces of the absorbent wick are exposed to an aerosolisable liquid nicotine- (or some other pharmaceutically or therapeutically effective medicament) containing formulation (not shown) which the cartomizer is adapted to receive prior to use. Screw threaded portions 14, 16 are provided at either end of the cartridge which facilitate secure connections to, on the one hand, an air flow regulator component 20 and on the other hand a mouthpiece and liquid charging assembly 22. Air flow regulator 20 and mouthpiece assembly are provided with corresponding threaded portions 22, 24 respectively, and a plurality of rubber or other suitable material O-ring seals are provided (not shown) as required to ensure that the connection between screw-threaded connection between these parts is essentially sealed and fluid- impregnable. The cartomizer assembly further includes a clear plastics material cylindrical outer sleeve 30 which, during assembly, is clamped between air flow regulator 20 and mouthpiece assembly 22, and again, appropriately sized and positioned O-ring seals (not shown) are provided to ensure that reliable fluid impregnable seals are created between both annular ends 32, 34 of the sleeve and the air flow regulator 20 and the mouthpiece assembly 22 respectively. Thus, when completely assembled, two separate chambers are defined within the cartomizer 2, the first consisting essentially of the cylindrical hollow interior of the cylindrical cartridge 4, and the second being the generally annular cavity defined between said cartridge and the interior surface of the cylindrical sleeve 30 and it is into this annular cavity that the nicotine-containing liquid is deposited prior to use through the mouthpiece and charging assembly 30 through an appropriate charging slot (not shown) provided in assembly 22. Thus the outer annular cavity functions as a reservoir which perpetually feeds the wick 4A disposed in the interior chamber as long as there is fluid in the reservoir and which thus submerges at least some of one end of the wick, when the arrangement is assembled and is vertically orientated, as it would most commonly be when not being used (in the figure, the various components are shown horizontally, purely for illustration purposes).

The wick4A is typically fabricated using fibres of a highly absorbent material such as cotton or some organic or inorganic synthetic equivalent material which are compacted, and/or spun, wound, or otherwise clumped together. As briefly mentioned above, in order that the aerosolizable liquid may soak into the wick, a plurality of slots 10, 12 are provided so that portions of the wick layer are exposed thereby, and liquid contained within the annular cavity surrounding the wick and coil arrangement is in direct contact with said exposed wick layer portions which thus absorb and become soaked with the said liquid beneath the level of said liquid. As the name suggests, the wicking nature of the absorbent material wick encourages the flow of liquid within the wick from the soaked regions to other regions not ordinarily submerged in liquid, and while the distribution of liquid throughout the wick is far from uniform, in general the wicking effect is sufficient to ensure that the majority of the wick is at least moist if not entirely soaked with the aerosolizable nicotine-containing liquid formulation.

There are further aspects of prior art cartomizers which deserve mention. Firstly, the coil of the wick and coil assembly must of course be electrically connected to the battery, and such electrical connection is most commonly achieved by means of a simple two-pole screw thread connection indicated generally at 38 provided on a distal closed end of the air flow regulator. For example, the screw thread connection may comprise firstly an exterior screw thread by means of which an electrical connection is achieved to one pole of the battery, and secondly an interior spigot or pin by which electrical connection is achieved to the second pole of the battery. Thus, as the cartomizer is screwingly connected to the battery, reliable and robust electric and mechanical connections therebetween are automatically achieved. It is generally desirable, though not always achievable, that there is some segregation within the cartomizer between the liquid within the cartomizer and the coil such that the coil is not entirely or partially submerged in liquid, and that the heating action of said coil is thus directed predominantly on the wick and the liquid absorbed therein. As will be understood from the above, the various O-ring seals provided as part of the cartomizer assembly ensure that the annular liquid-containing cavity to the exterior of the wick and coil assembly is effectively isolated from its hollow interior in which the coil is disposed. One of the fundamental reasons behind such isolation relates to the required airflow which is to occur within the cartomizer assembly when the vaping device is active and heat from the coil is causing aerosolization of the absorbed liquid in the wick.

To explain further, modern cartomizers such as that illustrated in Figure 1 provide not only a confined chamber in which aerosolization of a nicotine-containing liquid can occur (this chamber most commonly being the interior of the wick and coil assembly), but also air inlet and outlet regions between which air can be caused to flow along a predefined path into, through and out of the cartomizer assembly during each and every user inhalation. Thus, referring again to Figure 1, the cartomizer assembly includes a mouthpiece component 26 consisting of a short hollow plastic tube or plug which is sealingly inserted into, or which forms an integral part of the mouthpiece assembly 22. For most prior art wick-and-coil vaping devices, the mouthpiece component is nothing more than a simple hollow tube which merely functions as an extension of the cartomizer assembly and which is in communication with the interior aerosolisation chamber through a suitable aperture (not shown) provided in the mouthpiece assembly, and also as a means around which a user can purse his lips easily and quickly prior to and during an inhalation. At the opposite end of the cartomizer assembly, the air flow regulator 20 includes an adjustable regulator indicated generally at 23 by means of which the circumferential dimension of slot 23A can be enlarged or reduced, in the latter case to a zero, in which case ambient atmosphere is largely precluded from entering the cartomizer assembly with the result that the resistance to suction applied at the mouthpiece as hereinafter described will be very high. Of course, air flow regulator 20 can be adjusted to according to user preference. As will be appreciated from the foregoing, modern cartomizers can be quite intricate in terms of their constituent components and the assembly thereof, but in essence they are relatively rudimentary devices - all that is required is a reservoir for nicotine-containing formulation, a wick to absorb it, and a coil to heat the soaked wick up to, in most cases, between 150-250 deg.C to cause aerosolisation of the liquid soaked in the wick, and a mouthpiece and appropriate air passageways to allow a user to suck the aerosol from the cartomizer. Despite their rudimentary nature, cartomizer assembly is time consuming, largely manual, and thus costly, and furthermore the vast majority of modern cartomizers are not disposable, and simply provide a reservoir for a relatively large quantity (maybe 3- 4 or more days worth, depending on frequency of use) of nicotine containing formulation, which is repeatedly aerosolised when the vaping device, and thus the coil, is activated. There is very little care taken to ensure any consistency of aerosolisation, and indeed the resulting aerosols can vary significantly between successive aerosolisations, both as regards their constituents and the respective phases or intermediates thereof in which those constituents exist within the aerosol, and of course the temperature thereof.

The present invention adopts a very different, indeed somewhat revolutionary, approach and seeks to provide a different type of vaping device wherein an essentially disposable substrate component is pre-dosed with a relatively much smaller amount of a nicotine- containing formulation, for example being equivalent to that which a smoker of a conventional tobacco product, in particular a cigarette, might be expected to consume during a single day, if that smoker consumed some largely constant number, e.g. 5, 10, 15, 20 etc., of the generally the same, or same strength cigarettes on each and every such day.

In particular, the present invention, in some embodiments, provides a sintered plastics material substrate having a porosity which renders them at least if not more absorbent than conventional cotton wicks, and having significant porosity and wicking characteristics at least comparable to, if not actually significantly better than such conventional wicks. Furthermore, the present invention seeks to provide a solid, rigid generally cuboid shaped substrate to one or more surfaces of which can be automatically bonded, deposited, printed or otherwise applied an appropriately rated heater component in automated fashion and which can thus directly thermally conductively apply heat to the substrate and whatever formulation said substrate may have previously been impregnated with. Yet further, the invention provides a substrate of suitable dimensions and physical characteristics (e.g. porosity, absorbency, wicking etc.) such that the substrate can be "pre dosed" during manufacture so that the substrate can function not only as a heater, but simultaneously as a reservoir for any conventional or modern nicotine containing formulations, with both the dimensions of the substrate and the nature of the formulation, particularly as regards its concentration of nicotine, being carefully selected so as to correspond to the daily requirement for nicotine of smokers of conventional tobacco products.

Referring now to Figure 2, there is shown a plan view of a substrate according to the present invention and indicated generally at 40 and having been printed, for example as described in Applicant's own International application, PCT/EP2019/050533, with a single continuous pattern of an electrically conductive material and indicated generally at 42 and which is usefully separated into two distinct portions 44, 46 lying on either side of a notional dividing line shown in dotted at 45. Portions 44, 46 together constitute the entirety of the heating component which is applied to the substrate in accordance with the present invention, and in the illustrated arrangement represent approximately two thirds and one third of the total substrate surface area respectively. The first portion 44 comprises three separate contact portions 44A, 44B, 44C, whereas the second portion 46 comprises two separate areas 46A, 46B, being heating element portions, of the each consisting of a plurality of adjacent substantially linear parallel parts, some of which are referenced at 46C.

As can be seen in Figure 2, areas 46A, 46B each comprise 10 individual linear parallel parts 46C which are each connected to respective adjacent linear parallel parts at their distal ends so that said adjacent parallel linear parts together form an essentially meandering serpentine pattern of individual conductors in each of areas 46A, 46B, whereas area 44 comprises only three single very much larger conductors which form electrical contacts and by means of which an electrical current can be easily applied (and importantly without any great lateral precision) to the printed conductive pattern as a whole. Although the single substrate 40 of Figure 4 is shown as having only three contact portions 44A-C and 2 intervening and interconnected patterned areas 46A, 46B, alternative arrangements are possible, in particular wherein 5 contact portions and 4 similarly intervening and interconnected patterned areas are printed, preferably arranged either adjacently in a single row, or yet more preferably, arranged in 2 rows, each row containing a pair of adjacent patterned areas.

In Figure 3, various dimensions are provided, both of the substrate itself, and the printed areas thereof. However, it should be understood by the skilled reader that the dimensions of the substrate can be selected as required, depending on requisite operating parameters, as well as (a) the amount of formulation which the substrate is required to be absorb and be pre-dosed with, (b) the concentration of nicotine in that formulation, and (c) the daily nicotine requirement of the type of smoker that the pre-dosed substrate is designed for.

Of course, if the particular vaping device is adapted to receive a substrate of fixed dimensions, then the porosity and absorbency of the substrate may require to be altered so that the substrate can absorb a sufficient volume of fluid, and the concentration of nicotine within that formulation can also be selected so that the substrate still remains suitable for a particular type of smoker, e.g. a heavy or light user, of cigarettes, pipe tobacco, cigars etc.

Also, although the foregoing description relates to a sintered highly porous substrate which is to which a heating component is applied by printing an electrically conductive ink, the present invention is to be considered as extending to other types of heating components and other methods of application thereof, the only requirement being that the heating component, or at one surface of the generally resistive heating element(s) thereof, is disposed in substantially co-planar relationship with the larger exterior essentially planar surfaces of the substrate.

As can be appreciated from Figures 2 and 3, the substrate is essentially cuboid in shape, with substantially planar upper and lower surfaces 50A, 50B, which are relatively much larger than the parallel pairs of edge surfaces 51 A, 51 B and 52A, 52B respectively, and the heater element portions 46A, 46B (at least) of the heater component as a whole are applied to surface 50A. In some embodiments, an identical heater component may be similarly bonded to the lower surface 50B, so that the substrate is effectively sandwiched between two heater components.

As previously suggested, as the substrate is a sintered component, it is possible and indeed preferred in some embodiments, that an initially separate heater component be placed atop the initially granular or fibrous precursor material within the sintering mould prior to sintering such that when the sintering process is carried out, the heater component becomes physically bound to and partially within the sintered substrate as the precursor material physically changes state as a result of the sintering. In an alternative embodiment, an initially separate heater component may be bondingly applied, for example with a suitable adhesive, directly to and over one of the largest surfaces of a previously sintered substrate, such bonding application of the heater component to the substrate thus being carried out entirely separately from and subsequent to the sintering. In any case, however, the result is always that at least one surface of at least the resistive element portion of the heater component is disposed in substantially co-planar relationship with the surface of one of the largest planar surfaces of the substrate. As illustrated in Figures 2 and 3, it can be seen that the contact portions of the heater component are also disposed on and over one of the largest planar surfaces 50A of the substrate, and that said contact portions cover an area which is greater than that covered by the heater element portions 46A, 46B. In some preferred embodiments, the heater element portions may cover a much larger area of the substrate surface in or on which they are disposed. For example, that or those portion(s) of the substrate in or on which one or more heater element portions 46A, 46B are provided, in the illustrated example defined between notional dividing line 45 and one free end of the substrate, may be substantial in that it may be more than 50% of the substrate surface area, with the remaining area being that within, on or over which the two or more contact portions 44A, 44B, 44C are disposed. In preferred arrangements, this percentage may lie anywhere between 50-100%, and in the lattermost case, where only heater element portions 46A, 46B are provided on, in or over the said substrate surface, the two or more contact portions 44A, 44B, 44C would be provided on one or more of the adjacent, perpendicularly disposed edge surfaces of the substrate, as further explained below with reference to Figure 3A. As can be seen in Figure 3A, again substrate 55 is essentially cuboid in shape, with substantially planar upper and lower surfaces 56A, 56B, which are relatively much larger than the parallel pairs of edge surfaces 57A, 57B and 58A, 58B respectively. In the arrangement shown, the heater component consists of a single meandering heater element portion 59A arranged over substantially the entire length and width of the substrate surface 56A and covering anywhere between 30-80% of the total area thereof, with each remote end thereof terminating in a contact portion 59B which, in the illustrated arrangement, are each disposed on opposite edge surfaces 57A, 57B respectively, though of course said contact portions may both be disposed on one and the same edge surface, on any pair of edge surfaces, or even in some preferred embodiments, one the opposing large surface 56B of the substrate. In these particular embodiments, it is preferred that the heater component is initially a completely separate and discrete article, and either embedded into and over the relevant surfaces by being present in the sintering mould when sintering occurs, and thus naturally and automatically physically bonded to the sintered substrate, or bondingly applied, for example using a suitable adhesive, to the substrate after sintering thereof has occurred. As with other embodiments, an identical heater component may be similarly applied to, within, and/or over the lower surface 56B, so that the substrate is effectively sandwiched between two heater components. In this case, of course, the contact portions for each such heater component would be arranged discretely and electrically separate from one another in any one or more of the edge surfaces 57A, 57B, 58A, 58B.

One particular advantage of the embodiment illustrated in Figure 3A is that electrical connection of the heater assembly can be achieved directly and only by appropriate interaction with one or more of the edge surfaces of the substrate, for example when a pre-dosed substrate is inserted into a vaping device ready for use, and thus without any interference with the relatively much larger upper and or lower surfaces of the substrate from and through which aerosolization of formulation extant within the substrate will predominantly occur when the heater elements become hot. This arrangement is preferable because in this case, aerosolization can occur on and over substantially the entire surface of the substrate on which those heater element portions are provided, and is not restricted or otherwise hindered by the contact portions which may have a comparatively significant surface area.

Turning now to Figure 4, this shows a substrate 60, formed by sintering an initially particulate, granular, powdered or fibrous pre-cursor material, and within which a heating component indicated generally at 62 is substantially completely embedded. In some embodiments, the heater component may be an initially separate article, for example in the form of a thin conducting foil or film, or even simply a conducting wire, ideally flattened so as to be substantially planar in configuration, and comprising distinct separate contact portions and resistive heating element portions 64, 66 respectively which electrically connected together. In order to fabricate a substrate as illustrated in the Figure, an appropriately shaped and sized sintering die (not shown) would first be half-filled with pre cursor material, and then the heating component would be disposed on top of the precursor material so that free ends 64A of the contact portions 64 were disposed adjacent and contiguous with the die walls, before the remaining vacant die half subsisting above the heater component was filled up with precursor material, whereupon the sintering process could be carried out. Fabrication in this manner would of course ensure that the contact portion free ends 64A would be disposed within one of the various side walls as illustrated in the Figure, and a reliable and effective electrical connection could be achieved therewith, as required.

As regards the relevant dimensions of the heater element portions 46A, 46B, 66, relative to those of the contact portions 44A, 44B, 44C, 64, in the embodiments shown in Figures 2, 3, 4, it can be seen that the heater element portions are significantly less in area than the contact portions. This of course need not be the case, and in some embodiments, the size of the contact portions, in particular their length dimension, may be very much smaller than the corresponding dimensions of the heater element portions, for example one or more orders of magnitude less. In some particularly preferred embodiments, one or both of the length and width of the heater element portions may be similar, but slightly (e.g. 0.2-2mm) less than the corresponding dimensions of the substrate so that the heater element portion (including interstitial areas between individual elements thereof) occupies more than 30-35%, preferably more than 50%, and most preferably between 60-80% of the relevant cross-sectional area of the substrate, and the contact portions electrically connected thereto are very much smaller by comparison.

Such an arrangement is illustrated in Figure 5, wherein reference numbers 70-76 identify corresponding parts to references 60-66 used in Figure 4. Of course, although not specifically illustrated, this configuration could apply equally to earlier embodiments shown in Figures 2-4 and described above, wherein the heater component is printed, embedded, or otherwise secured to, within, and/or over a relevant surface of the substrate, and such arrangements should be understood as being within the scope of the present invention. As the skilled reader will understand, enlarging the heating element portions will result in a larger area or volume of the substrate being heated when the vaping device in which the substrate is used is activated, which will in turn result in more of the absorbed formulation extant within the substrate being aerosolised, and a more voluminous aerosol being produced. The skilled person will also understand that the selection of the dimensions of the heater element portions of the heater component will thus depend on operative requirements, and may be adjusted accordingly.

As prescribed herein, the present invention provides a heater assembly comprising both a substrate and heater component as described above.