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Title:
AN EXCITATION DEVICE FOR AN ELECTRONIC INHALER, A METHOD OF ELECTRONICALLY CONTROLLING AN EXCITATION DEVICE OF AN ELECTRONIC INHALER, AND AN ELECTRONIC CONTROL CIRCUIT THEREFOR
Document Type and Number:
WIPO Patent Application WO/2019/068780
Kind Code:
A2
Abstract:
An excitation device for an electronic inhaler is disclosed. The excitation device is designed to be disposable and is pre-dosed with an amount of a formulation including nicotine which is to be at least partially aerosolised by an excitation device when supplied with an excitation energy. The excitation device consists of a substrate material to one side of which is fixedly applied an excitation means comprising one or more contact portions by means of which an appropriate energy source can be connected and at least one excitation element over which the said amount of formulation is applied, said one or more contact portions being connected or otherwise in communication with said at least one excitation element such that energy received through the one or more contact portions is communicated to the at least one excitation element causing sufficient excitement to cause at least partially aerosolisation of any formulation extant thereon. In accordance with the invention, the formulation is disposed and applied over only the excitation element, as opposed to the contact portions, so as to be in direct physical contact therewith such that at least one measurable physical property of the excitation element, usually an electrical property such as resistance when the excitation element is electrically powered, is modulated to at least some degree by virtue of said direct physical contact so that measuring the physical characteristic provides an indication of the remaining volume of formulation extant on the excitation element. Both the substrate and the at least one excitation element are substantially chemically inert as regards the formulation so that the chemistry of the formulation is not changed between successive excitations. A method of electronically controlling such excitation device of an electronic inhaler, and an electronic control circuit therefor, are also disclosed.

Inventors:
LAWSON DAVID (GB)
DIGNUM MARK (GB)
Application Number:
PCT/EP2018/076935
Publication Date:
April 11, 2019
Filing Date:
October 03, 2018
Export Citation:
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Assignee:
PROJECT PARADISE LTD (GB)
International Classes:
A24F40/46; A24F40/50; A61M11/04; A61M15/00; A61M15/06; B05B17/06; A24F40/10
Other References:
None
Attorney, Agent or Firm:
OPUS IP LIMITED (GB)
Download PDF:
Claims:
CLAIMS

1. An excitation device having been pre-dosed with an amount of a su bstance capable of being at least partially aerosolised, or from which one or more vapours may be released when sufficiently excited by said excitation device when supplied with an excitation energy, said su bstance including at least one active composition which is to form part of the aerosol or vapour as the case may be, said excitation device comprising a substrate material to one side of which is fixedly applied an excitation means comprising one or more contact portions by means of which an appropriate energy source can be connected and at least one excitation element over which the said amount of su bstance is applied, said one or more contact portions being connected or otherwise in communication with said at least one excitation element such that energy received th roug h the one or more contact portions is commu nicated to the at least one excitation element causing excitement thereof which in tu rn sufficiently excites the su bstance above it to at least partially aerosolise it or to cause at least some vapour to be released therefrom,

characterised in that

the said at least one excitation element is distinctly separate from the said one or more contact portions and the said amount of substa nce is disposed over substantially on ly the said excitation element so as to be in contact therewith and in such a manner that at least one measurable physical property of the excitation element is modu lated to at least some degree by virtue of said contact.

2. An excitation device accofrding to claim 1 characterised in that the substrate and the at least one excitation element are substantially chemically inert as regards the substance such that, regardless of the states of excitation of either the excitation element or the adjacent su bstrate material, there is no chemical reaction between them and either the su bstance as a whole, or the chemical constituents components thereof.

3. An excitation device according to any preceding claim wherein the excitation mea ns is electrically conductive and capable of being excited by the application of an electric current.

4. An excitation device according to claim 3 wherein the excitation element is sig nificantly more resistive to the flow of electric current than the contact portions and constituted of a material which rises in temperatu re when an electric current flows throug h it.

5. An excitation device according to claim 3 or 4 wherein the excitation means consists of at least two contact portions in electrical communication with an excitation element connected therebetween.

6. An excitation device according to claim 5 wherein the excitation means comprises th ree distinct contact portions in commu nication with a pair of excitation elements, one of said contact portions fu nctioning as a common ground contact for both excitation elements, and the remaining two contact portions serving to facilitate independent energisation of said excitation elements.

7. An excitation device according to claim 5 wherein the excitation means comprises five distinct contact portions in electrical communication with four separate excitation elements, one of said contact portions fu nctioning as a common ground contact for the said four excitation elements, and the remaining four contact portions serving to facilitate independent energisation of said fou r excitation elements.

8. An excitation device according to any of claims 3-7 wherein the excitation element takes the form of a single conductor arranged in a meandering "back-and-forth" type pattern having a shape which is at least partially defined by portions of said conductor.

9. An excitation device according to claim 8 wherein the overall shape of the conductor pattern is one of: that of any regular or irregu lar polygon, an ellipse, and a circle.

10. An excitation device according to any of claims 3-9 wherein the average width of the conductor in the excitation element is narrower as compared to that of the contact portions by a factor selected from one of the following ranges: 2-3, 3-5, 5- 10.

1 1.An excitation device according to any preceding claim wherein the su bstrate material is selected from one of the following materials, or any combination thereof: glass, a silicate g lass, a borosilicate glass, a soda-based glass, a lime- based glass.

12. An excitation device according to any preceding claim wherein the substance is one of: an essentially liquid formu lation, and a solid, and the active composition therein is nicotine.

13. An excitation device according to claim 12 wherein the su bstance further comprises one or more of the following excipients: g lycerol, polyethylene glycol (PEG), propylene glycol, and Xanthan gu m.

14. An excitation device according to any of claims 12-13 wherein the excitation device is pre-dosed with an amou nt of substance in which the total quantity of nicotine is of the order of one of the following ranges: 0.3mg- 1.5 mg, 0.4mg-1 mg, and 0.5-0.75mg.

15. An excitation device according to any preceding claim wherein the substance is a liquid whose viscosity exhibits some deg ree of one or more: time-dependency and temperatu re- dependency.

16. An excitation device according to any of preceding claim wherein the su bstance is a liquid at room temperatu re, said liquid being at least partially pseudoplastic.

17. An excitation device according to any preceding claim wherein the substance is a liquid formu lation, and the amou nt applied to the excitation element is so small that only a tiny droplet, having a maximum diameter of the order of < = 5 mm is applied over the excitation element.

18. An excitation device according to claim 17 wherein the excitation element is substantially circular in outline or cross-sectional shape over the substrate and of a diametral and circumferential size corresponding to that of a drop of liquid formulation applied thereover.

19. A control circuit for an excitation device having been pre-dosed with an amou nt of an aerosolizable substance or one from which one or more vapours may be released, wherein said control circuit is adapted to selectively and repeated ly provide an excitation energy to said excitation device which, when in a state of excitation, causes at least some degree of aerosolization or vaporisation of said substance, said control circuit comprising switch means for selectively activating said control circuit and thus energising said excitation device, first con nection means whereby said excitation device can be releasably connected to said circuit and second connection means whereby said control circuit is connected to a source of a suitable excitation energy, active measurement means whereby at least one physical characteristic of the excitation device may be measu red du ring energisation thereof, said physical characteristic being one which is at least partially dependent on one or both of the amou nt of substance at any time present on said excitation device, and the specific composition of said formu lation as regards its constituents, and memory means for storing one or more of:

recent historic measu rements of said physical characteristic of the excitation device cu rrently con nected to said control circuit, and

one or more profile data sets describing how the physical characteristic being measured changes for a specific excitation element depending on the amou nt of formulation extant at a particular time on said excitation device, characterised in that

the control circuit further comprises adaptive control means whereby the energy supplied by the control circuit to the excitation device is regulated in a predetermined manner according to at least one of the data previously stored in said memory means.

20. A control circuit according to claim 19 wherein the adaptive control means regulates the su pply of energy to the excitation device in a predetermined manner according to a particu lar one of said stored profile data sets, being that which is most closely correlated to one or both of a current instantaneous measurement of the said physical characteristic for the currently con nected excitation device, and one or more previous measurements of said physical characteristics stored in said memory means for the cu rrently con nected excitation device and which was measured du ring the current or a previous activation of the control circuit.

21.A control circuit accordi ng to either claim 19 or 20 wherein the control circuit includes energy regu lation means which is one of: a seprate component, and integral part of the adaptive control means.

22. A control circuit according to any of claims 19-21 wherein the memory means stores both recent historic measu rements of the measured physical characteristic of the excitation device while being supplied with the excitation energy, and one or more profile data sets.

23. A control circuit according to any of claims 19-22 wherein the memory means maintains a record of the most recently identified and/or selected profile data set.

24. A control circuit according to any of claims 19-23 which additionally includes a source of excitation energy being in the form of a rechargeable battery, and the active measurement means is adapted to measu re one or more of: the electrical current delivered to, electrical potential drop across, the electrical resistance of the excitation device.

25. A control circuit according to claim 19 and any claim dependent thereon wherein the control circuit fu rther comprises indication means being one or more of:: audible and visible, said indication means being caused to be activated by said control circuit when the adaptive control means makes a determination that the or a most recently or instantaneously measu red physical characteristic of the excitation device exists, at, proximate or beyond a terminal data point of the profile data set currently selected and identified as being that most representative of the operating characteristics of the currently con nected excitation device, and being used to regulate the energy supplied thereto.

26. A control circuit according to any of claims 19-25 wherein the second connection means which con nect the control circuit to the sou rce of excitation energy is an electromechanical con nector including cooperating parts.

27. A control circuit according to any of claims 19-25 fu rther including one or more of: ambient air pressu re, temperatu re, humidity sensing means.

28. A method of operating a control circuit as hereinbefore described including the steps of activating the control circuit to initiate the su pply of an excitation energy to an excitation device pre-dosed with an amount of an aerosolizable/vaporisable su bstance applied to a suitable su rface thereof, said excitation energy being transmitted, in transmuted form as may be the case, from said excitation device to said su bstance to cause at least some aerosolisation/vapoursiation thereof, said excitation energy being continued to be su pplied for as long as the control circuit remains activated, repeated ly measu ring at least one physical characteristic of the excitation device while activated, said physical characteristic being dependent, at least to some extent, on at least one of: the amount of substance extant thereon, and the chemical composition of said substance, and which therefore changes prog ressively as the su bstance is aerosolised/vapourised, storing a plurality of the measu rements arising from the preceding step, together with some indicator of time,

characterised in that the control circuit performs the further steps of

comparing a plurality of the previously stored time-dependent measu rements of the physical characteristic with corresponding data in one or more reference performance profile data sets su bstantially completely describing the time-dependent fu nctional performance of excitation elements having amounts of substance thereon in terms of the physical characteristic being measured,

determining at least a particu lar one of said reference performance profile data sets, being that reference performance data set having data points which best fit the data having been most recently measured and stored, and thus being at least partially representative of the amount of su bstance cu rrently extant on the excitation device,

selecting the said particu lar one reference performance profile data sets as that according to which the control circuit should function immediately u pon and subsequent to said selection, regulating the supply of excitation energy in accordance with the particular reference profile data set selected so as to achieve the desired aerosolisation/vapou risation of that amount of su bstance henceforth and which, as a resu lt of the previous steps, said control circuit has determined as being currently extant on the surface of the excitation device.

29. A method according to claim 28 wherein the storing of the plurality of measu rements is one or both of: temporary and permanent.

30. A method according to any of claims 27-29 further including the steps of

automatically terminating the cu rrent activation of the control circuit after a predetermined activation duration time, stored in persistent memory and which is both u nchanged between, and accessible by the control circuit in, successive activations, has ela psed from the initiation of the cu rrent activation, determined from one of: the time-stamp for the first measu rement of the physical characteristic for the cu rrent activation, and a time-stamp stored by said control circuit immediately u pon any activation thereof.

31.A method according to any of claims 27-30 further including the step of preventing, after any previous activation of the control circuit, the supply of excitation energy to the excitation device unless and until a predetermined amount of time has elapsed since the end of the previous activation determined by comparing one of:

a cu rrent time, and the time stamp of the most recently stored measu rement of the physical characteristic having occurred during the current activation,

with one of:

a time-stamp for the last measurement of the physical characteristic taken du ring the said previous activation and a simple time stored during said previous activation,

and establishing whether the difference in those times exceeds an activation delay time value stored in persistent memory so as to be available to, and unchanging between successive activations of, said control circuit.

32. A method according to any of claims 27-31 including the further step of recognizing, based on a comparison between one or more of the measu rements of the physical characteristics stored du ring a previous activation of the device, and one or more measurements of the said physical characteristic taken during the current activation, whether the excitation device currently connected to the control circuit is that which was con nected to the control circuit du ring said previous activation.

33. A method according to any of claims 27-32 fu rther including the step of determining when the currently connected excitation device is, or is about to become, spent.

34. The method of claim 33 further including the step, upon making a determination that the currently connected excitation device is, or is about to become, spent, communicating the existence of this condition to appropriate indication means.

35. The method of any of claims 27-34 fu rther including the steps of establishing, from a comparison of one or more of:

one or more of the most recently measured values of the physical operating characteristic of the excitation device, and one or more corresponding values obtai ned from the cu rrently selected reference performance profile data set,

whether the amou nt of substance extant on the excitation device is or is becoming neg ligible by determining from said comparison that there is either no difference between a respective pair of values, or that the difference between them is below a th reshold value.

36. A method according to claim 35 and including the further step, if the control circuit establishes that the amount of formu lation extant on the excitation device is or is becoming negligible, of commu nicating the existence of such condition to appropriate indication means.

Description:

Excitation Device of an Electronic Inhaler, and an Electronic Control Circuit therefor

Field of the Invention

The present invention relates to an excitation device for an electronic inhaler, a method of electronically controlling an excitation device of an electronic inhaler, and an electronic control circuit adapted to electronically control said excitation device. More specifically, the present invention is concerned with providing a low-cost excitation device which is an essentially disposable or consu mable item and to which a precisely controlled amou nt of at least one chemically, therapeutically, pharmaceutically or medicinally active compound or substance has been applied, said compou nd or substance usually but not necessarily being dissolved or otherwise supported within a carrier formulation with which the excitation device is precisely and accurately pre-dosed as part of the manufacturing process of said heating element.

For the avoidance of doubt, the electronic inhalation devices with which the present invention is primarily concerned are those that are often considered as "active" in that they include some form of element, usually a heating element but other forms of excitation of the element may be considered, which requires a sou rce of power which is selectively activated as desired, whereu pon the active compou nd or substance (or a formu lation containing it) is heated (or otherwise excited) to such an extent that a non-negligible quantity of the active compound is released into the su rrounding atmosphere in at least one of a vapourized, atomized, aerosolized or gaseous state. By contrast, purely passive inhalation devices do not require a heating element, and operate effectively at room temperatu re and pressure pu rely as a resu lt of the pressure differential capable of being created by the human mouth, i.e. by suction only.

Although active electronic in halation devices may have many purposes, and may be capable of being designed to operate as inhalers for a variety of different active compounds or substances, the most common class of electronic inhalers cu rrently in use today are those known as electronic nicotine delivery systems (EN DS, covering both singu lar and plural), for which a usefu l description has been published by the World Health Orga nisation (WHO) Fra mework Convention on Tobacco Control (FCTC) u nder reference FCTC/COP/6/10 dated 21 Ju ly 2014, easily found at the WHO website. Although the following description is provided with exclusive reference to EN DS, it is to be understood that the present invention is not specifically limited to devices adapted for delivering on ly nicotine, and the term "EN DS" shou ld be interpreted as encompassing devices capable of delivering su bstances other than nicotine to a user.

Background to the Invention

EN DS have been in widespread use now for some years, and although there has been and continues to be little concrete scientific evidence as to how harmfu l they are to human health, in particu lar hu man lungs, it is largely beyond dou bt that the use of any EN DS is significantly less harmful than the smoking of combustible tobacco products, such as cigarettes, cigars, cigarillos, pipes, and hand rolling tobacco. I ndeed, some estimates consider EN DS to be safer, as compared to a corresponding amount of a combustible tobacco product containing effectively the same amou nt of nicotine, by as much as one or two orders of magnitude. The primary reason for the comparative health benefit of EN DS as compared to conventional combustible tobacco products is that the nicotine-containing smoke in haled by users of the latter contains significant levels of carcinogens and other toxicant products of combustion, whereas the so-called vapou r in haled by users of ENDS consists primarily of nicotine, g lycerol and/or propylene g lycol and derivatives of these compou nds, together with natu ral and/or synthetic flavou ring compositions often added to the liquid formulations utilised in EN DS.

Of course, in the case of both EN DS and combustible tobacco products, the chemically active su bstance is nicotine (C 1 0H 14 N2), a potent parasympathomimetic stimulant and alkaloid. In essence, nicotine is a drug and like many d rugs, it is hig hly addictive to hu mans. I n sufficient concentrations, nicotine is also hig hly toxic to humans, and although nicotine only constitutes approximately 0.6- 3.0% of the dry weig ht of tobacco depending on strain, variety and processing tech niques, mere ingestion of only one or two cigarettes, in which there might be as much as 50mg of nicotine and possibly more, can cause quite serious toxic reactions. I n large enough concentrations in the hu man body, nicotine can certainly be fatal, and it is possible to achieve such concentrations with on ly relatively small amounts, e.g. 1 -2g. Those skilled in the art will immediately understand therefore that the dose of nicotine ad ministered by an EN DS is of critical importance - in genera l, the dose must be sufficient to satisfy the physiological cravings experienced by users addicted to nicotine, but (arguably) less than that which is typically delivered by a corresponding combustible tobacco product in a similar time scale so that the EN DS can be effective, at least partially, in reducing an addict's dependency on the drug and thus fu nction as a smoking cessation aid. To expand further on current ENDS, the most common form of device is a so-called vvick-and-coil device wherein an electrical heating coil is disposed adjacent, around, within or otherwise proximate a moisture absorbent wick such that a liquid extant within the wick can be heated sufficiently rapidly and to a sufficient degree to cause at least some of that liquid and/or one or more of its constituents to be vapourised, atomized, aerosolized or be otherwise promoted from the wick into the air surrounding the wick in a gaseous or quasi-gaseous phase. The wick-and-coil arrangement may take many different forms, but most commonly both said components will be located within a cartridge or reservoir (a so-called "cartomizer", such term being a conflation of the words "cartridge" and "atomizer") which also contains the nicotine-containing liquid which has been or is to be drawn into the wick. The cartomizer is provided with a mouthpiece at one end around which a user purses their lips to create a seal and applies a suction pressure to cause a stream of air to flow through the cartomizer, over and around the wick, and particularly in the region of the coil, and it is in this user-initiated airflow that the liquid and/or its constituents in their gaseous or quasi- gaseous states are entrained prior to entering the mouth of the user before being ultimately inhaled into said user's lungs. Of course, in order for the coil to be heated, a source of electrical power is required, and in this regard, often the most dominant component in any modern ENDS is the rechargeable battery which may be either an integral part of the device as a whole, or a removable and/or detachable component thereof, but in any event, the cartomizer, and thus the heating coil is electrically connected to the battery and a simple switch is provided in a convenient location on the device so that the user can selectively apply and remove electrical current to and from the heating coil and essentially activate the device.

At this point, the physical process of smoking, as well as the chemical composition of tobacco smoke, are worth explaining.

The smoking of combustible tobacco products such as cigarettes is generally a three step process. In the first step, the suction step, ambient air is forcibly drawn into and through the burning end of the cigarette when the user applies a suction pressure by sealingly pursing their lips around the alternate end of the cigarette and then using the exterior and interior facial muscles to voiumetricaliy expand the mouth cavity so as to create a drop in pressure therein, thus causing air to flow. As this air passes through the burning end of the cigarette and into the elongate cigarette body behind it, it is polluted with many thousands of compounds (some estimates are in the region of >7000) produced by the combustion of the burning tobacco, some of which are toxic (i.e. "toxicants"), and some of which are carcinogens. In any event, the combustion of tobacco always releases the nicotine from the tobacco, and this along with the various other compounds form the smoke which is ultimately inhaled by the smoker during a second inhalation step. In this second step, the cigarette is withdrawn from the mouth which is then opened slightly to allow ambient air to enter, and at the same time, or immediately thereafter, with the majority of smoke from the first suction step still present in the user's mouth, the user exercises relevant diaphragm muscles to perform an inhalation. In simple terms, the user breathes in through their open mouth and in doing so, causes the volume of smoke present in their mouth to be drawn downwardly through the buccal cavity, into the pharynx and then the trachea, and then ultimately into the lungs. The third and final step is a standard exhalation in which the smoke extant in the user's lungs and which has not been absorbed, adsorbed, or otherwise retained within the lungs is expelled through one or both of the mouth and nose.

Tobacco smoke itself is known to be a highly complex mixture of gaseous, liquid and solid materials. One popular characterisation of tobacco is that of a concentrated aerosol of liquid particles, including water vapour («20%), suspended in an atmosphere consisting mainly of nitrogen, oxygen, carbon monoxide and carbon dioxide. Some studies have attempted to group tobacco smoke into a particulate phase (i.e. total particulate matter or TPM) and a gas/vapour phase, with the term "ta r" (or more recently, "nicotine-free dry particulate matter" or "NFDPM") being used to describe everything in tobacco smoke except nicotine and water. However, it is to be noted that several components of tobacco smoke (e.g., hyd rogen cyanide, formaldehyde, phenanthrene, and pyrene) do not fit neatly into this classification because they are distributed among the solid, liquid and gaseous phases, and importantly such distribution can depend to a greater or lesser extent on temperature. Thus the nature and composition of tobacco smoke is in an almost permanent state of flux, and depends on a wide variety of factors.

Modern ENDS are designed to function in a manner which essentially mimics the smoking of a combustible tobacco product, except that instead of producing a largely toxic and carcinogenic and thus harmful inhalable aerosol through a largely unregulated combustion of tobacco which is selectively and repeatedly intensified by a user during the first suction step of the smoking process, ENDS produce an aerosol from a nicotine-containing liquid (commonly referred to as "e-liquid" or "e-liquids") consisting of only relatively few chemicals and optionally one or more natural or synthetic flavourings, at least some of which are capable of being aerosolized when heated by a required amount over a relatively short time period (e.g. < 1 -5s) by a simple heating coil. It is important to note here that both the smoking of combustible tobacco products and the use of ENDS involve an almost identical repetitive "hand-to-mouth" physical action. It is known that this action is one of the physically (as opposed to chemically) addictive aspects of smoking tobacco, and it is no coincidence that EN DS are often also shaped like cigarettes, cigars or pipes so that users find them immediately familiar both in terms of their physical appearance and usage, and in terms of their pharmacology and d rug they deliver. Furthermore, smokers often equate (arguably falsely) the exhalation of the visible smoky aerosol with physiological feelings of satisfaction, and it is therefore desirable that EN DS also produce a similarly visible, smoke-like aerosol containing sufficient nicotine to satiate the cravings experienced by smokers deprived of the d rug, and which is also visible du ring exhalation to provide the user with whatever feelings of satisfaction they may thin k such exhalation provides.

I n terms of the absorption of nicotine into the bloodstream, whether by means of combustible tobacco products, EN DS or other passive nicotine delivery systems and devices, this can occur in the buccal cavity itself, the pharynx, the upper reaches of the trachea and of course the lung itself, and the extent to where and when such absorption occu rs is dictated at least to some extent by particle size. For instance, the majority of the particles present in tobacco smoke have a mass median aerodynamic diameter (M MAD) that is su b-micrometre, and thus such particles are lu ng- respirable by hu mans, meaning that such particles can enter the hu man bloodstream via the lungs. I n EN DS, the range of particle sizes is similar to that of conventiona l cigarettes, with most particles being in the u ltra-fine range (100-200n m), and therefore the chemica ls used in EN DS, including nicotine, will be similarly lu ng-respirable.

One of the major disadvantages of modern wick-and-coil EN DS is the rather crude nature of the heating element, and the concomitant variability in the quality and consistency of the aerosol it produces from the nicotine-containing liquid with which it either comes into contact or with which it is in close proximity. A further disadvantage of such devices is the wick itself, which is prone to progressive degradation as a result of being repeatedly completely or partially saturated with nicotine-containing liquid, and then forcibly and rapidly heated to a temperatu re approaching or in excess of the boiling point of nicotine (247 deg.C), most commonly about 260 deg.C, after which the heating energy is removed and the wick cools similarly rapid ly back down towards ambient temperatu re. A yet fu rther disadvantage arises from the materia l of which the wick is fabricated - most common ly the wick is of a natural or synthetic woven fabric construction, and therefore natu ral ly prone to variabilities in performance in terms of moisture absorption and satu ration, and of course the heating and cooling characteristics of satu rated fabrics can be notoriously variable. Perhaps most disadvantageously, certain ly from a medicines and healthcare products regulatory perspective (in the U , the Medicines and Healthcare Products Agency - M H RA - regulates, approves and licenses compositions for hu man treatment), not only can the quantity of nicotine within the aerosol produced with each activation of the device vary quite considerably, the on ly mechanism by which the amount of nicotine delivered within the aerosols can be controlled is largely if not entirely dependent on the concentration of nicotine within the e- liquid with which the cartomiser is charged. For example, e-liquids available u nder the brand name "Pure Mist® " are commonly provided with 4 different nicotine concentration levels, Omg (i.e. entirely nicotine free), 6mg (per ml), 12mg, and 18mg, and the e-liquids they provide are typically sold in small 10ml bottles. I n terms of the amount of nicotine delivered per in halation from an u nspecified EN DS, it is stated (on the 6mg bottle) that the amou nt of nicotine delivered is 25.82pg "per puff". The skilled reader will immediately appreciate that while the mg concentrations of nicotine liquid may be largely accurate, correct, and ca pable of being precisely measu red and verified, it is practically impossible to verify any claim regarding the "per puff" inhalation amou nt, especially to the microgram level of accu racy prescribed in the case of Pu re Mist® liquids, particularly given the general disadva ntages of EN DS referred to above.

More recently, and in response to ongoing and continuous safety and quality concerns espoused by health orga nisations and medicines regulatory bodies around the world and particu larly in Europe, the Eu ropean U nion has ag reed a revised Tobacco Products Directive (Tobacco and Related Products Regulations 2016). The TPD has i ntroduced regu lations applica ble to smoking-su bstitute devices, in particu lar EN DS, that will: a) limit the risks of inadvertent exposu re to nicotine by setting maximu m sizes for refill reservoirs, containers, tan ks, and ca rtridges (Article 20.3(a))

b) limit the concentration of nicotine in the liquid to 20 mg/ml (Article 20.3(b)).

c) prohibit the use of certain additives in the liquid (Article 20.3(c))

d) require that only hig h-purity ingredients are used in the manufactu re of liquids (Article 20.3(d)).

e) require that all ingredients (except nicotine) do not pose a risk to human health in heated or un heated form (Article 20.3(e))

f) require that all smoking-substitute devices deliver doses of nicotine at consistent levels under normal conditions of use (Article 20.3(f))

g) require that all products include child and tamper-proof labelling, fasteners and opening mechanisms (Article 20.3(g)).

h) require that all products meet certain safety and quality standards and to ensure that products do no break or leak du ring use or refill (penu ltimate and final sentences, paragraph 41 of the recitals). Of these, (f) is particularly relevant to the present invention because as suggested above, this requirement is extremely difficu lt to achieve in conventional wick-and-coil ENDS.

It is therefore an object of the present invention to provide a new type of EN DS, and in particular a new type of heater or other excitation device therefor which is designed to be a low-cost disposable item but which is nevertheless capable of aerosolising an amount of a formu lation containing at least one particu lar active composition or su bstance such that the concentration of the active composition or substance present in the aerosol produced is repeatably consistent.

Fu rther objects of the invention are to provide a control circuit for a heating element which ensures the consistent aerosoiisation of a formulation disposed on the heating element, and a method of controlling the aerosoiisation of a formulation on such a heating element such that the aerosol produced is relatively consistent as regards its constituents.

Summary of the Invention

According to the present invention there is provided an excitation device having been pre-dosed with an amount of a substance capable of being at least partial ly aerosolised, or from which one or more vapours may be released when sufficiently excited by said excitation device when supplied with an excitation energy, said substance including at least one active composition which is to form part of the aerosol or vapou r as the case may be, said excitation device comprising a substrate material to one side of which is fixedly applied excitation means comprising one or more contact portions by means of which an appropriate energy source can be connected and at least one excitation element over which the said amou nt of substance is a pplied, said one or more contact portions being connected or otherwise in communication with said at least one excitation element such that energy received throug h the one or more contact portions is commu nicated to the at least one excitation element causing excitement thereof which in tu rn sufficiently excites the su bstance above it to at least partially aerosolise it or cause at least some vapou r to be released therefrom,

characterised in that

the said at least one excitation element is distinctly sepa rate from the said one or more contact portions and the said amou nt of substance is disposed substantially over on ly the said excitation element so as to be in contact therewith and in such a man ner that at least one measurable physical property of the excitation element is modu lated to at least some degree by virtue of said contact. Preferably, both the substrate and the at least one excitation element are su bstantially chemically inert as regards the substance such that, regard less of the states of excitation of either the excitation element or the adjacent substrate material, one or more chemica l constituents of the substance are su bstantially u naltered by virtue of said direct physical contact.

Thus, by directly pre-dosing su bstantially on ly the excitation element part of the excitation device, as opposed to the contact portions thereof, with an amount of a substance, the physical characteristics of the excitation element are changed in some measu rable way. After such pre- dosing, each and every su bsequent aerosolisation and/or vaporisation caused by the excitation device becoming excited will cause either or both of

- a reduction in the volumetric quantity of the substance and/or one or more components thereof, and

- a change in its chemical characteristics and/or composition, as regards its constituents.

The fact that the substance remaining on the excitation device is in contact with it in such a way as to modu late at least one measurable physical property thereof means that it is thus possible for associated control circuitry to make various determinations as to one or more of

- the volumetric amou nt of substance amou nt remaining, and (possibly) also

- its chemical constitution, or at least a relevant aspect thereof, for example a concentration of one or more of the active compositions remaining in the substance after any aerosolisation or vaporisation.

When it is considered that it is the primary and intended purposed of the excitation device is to repeated ly aerosolise/vaporise the substance, and that with each aerosolisation/vaporisation which occu rs, the amount of substance extant on the excitation element will inevitably either reduce by some non-neg ligible amou nt and/or chemically change, particularly as regards a concentration of an active composition present therein, it can be u nderstood that the excitation device of the present invention can function not on ly to aerosolise/vaporise the substance, but also as a feedback device enabling control circuitry to make the relevant determinations/calcu lations.

I n most preferred embodiments, the su bstance is liquid formu lation, but in other embodiments, the su bsta nce may be solid, semi-plastic, or gel-like in terms of viscosity. Of cou rse, most preferably, the excitation energy will be electric, and the excitation means will be in the form of a conductor of electric current with the excitation element being preferably sig nificantly more resistive to the flow of electric current than the contact portions and thus heat sig nificantly when a suitable electric current flows th rough it. I n this particular case, the physical property of the excitation element which will be modulated as a resu lt of the direct physical contact with the formulation will be electrical resistance (Ω), and of course this property can be very readily measu red by an appropriate electrical control circuit which is most preferably simultaneously providing the electrical energy to said excitation means.

Preferably the su bstance will contain nicotine as the active composition, and will be in the form of an essentially liquid formulation, most preferably a liquid with sufficient viscosity and/or surface tension to be retained on the excitation element and substrate without sliding or dripping therefrom under gravity.

Fu rther preferably, the formu lation will consist of one or more excipients, for example glycerol, polyethylene glycol (PEG), or propylene glycol. Most preferably, the excitation device will be pre- dosed with an a mou nt of formulation in which the total quantity of nicotine is of the order of 0.3 mg- 1.5 mg, more preferably 0.4mg-1 mg, and most preferably 0.5-0.75 mg. I n preferred embodiments, the formu lation applied to the excitation device will be one of: a liquid, a solid, and a semi-plastic liquid. I n certain preferred embodiments, the formulation may be a liquid whose viscosity exhibits some degree of time- and/or temperatu re- dependency.

Fu rther preferably, the liquid may possess pseudoplastic qualities and include Xanthan gum. I ndeed, the viscosity of the formulation, and the manner in which it changes with time and/or temperatu re may be considered as important because it is desirable that the amount of liquid formulation which is at any time extant on the excitation element does not flow to any sig nificant extent over the surface of the device. In some embodiments, the amount of formulation applied to the excitation element is so small that on ly tiny droplets (for example having a maximum diameter of the order of 3mm or less) are applied over each of the excitation elements and are easily retained in place by virtue solely of liquid surface tension and meniscal effects. It will be appreciated by the skilled reader that when the excitation device is used in an inhalation device which u ndergoes the typical hand -to-mouth action common to smokers, it is important that the amount of formulation present on the excitation means is secu rely anchored in place over the excitation element, because on the one hand, on ly that amount of formu lation over and above the excitation element will be properly excited thereby (leading to proper and consistent products of the required aerosol having a correct dose of the active ing redient), and on the other hand, any reduction in the amou nt of formu lation over and above the excitation element not due to aerosolisation being caused thereby may give rise to erroneous resu lts when the physical characteristics of the excitation element a nd any extant formu lation thereon are measured, particularly if the formu lation flows to such an extent that one or more secondary d roplets form as they are separated from the primary droplet, and those secondary d roplets lie entirely to the outside of the perimeter of the excitation element, and thus have no direct physical i nteraction with it whatsoever.

Preferably, the excitation means will consist of at least two contact portions in electrical communication with a single resistive excitation element therebetween. Further prefera bly, the excitation means will comprise three distinct contact portions in electrical communication with a pair of excitation elements, one of said contact portions functioning as a common grou nd contact for both excitation elements, and the remaining two contact portions serving to facilitate independent energisation of said excitation elements. I n one pa rticular embodiment, the excitation means may comprise five distinct contact portions in electrical communication with four separate excitation elements, one of said contact portions functioni ng as a common g round contact for the said four excitation elements, and the remaining fou r contact portions serving to facilitate independent energisation of said four excitation elements. As prescribed in our co- pending applications, the contact portions and/or the excitation elements may be screen printed using a conducting screen printing ink, and such printing may occu r in a single pass with both contact portions and excitation elements being printed at the same time, or in multiple passes with the contact portions and excitation elements being laid effectively printed on the substrate material at different times, and possibly with different conductive printing inks. Rega rdless of the manner in which the contact portions and the excitation elements are applied to and affixed to the su bstrate material, in preferred embodiments it is desired that the excitation element takes the form of a single conductor arranged in a meandering "back-and-forth" type pattern having a shape which is at least partially, preferably predominantly, defined by portions of said conductor. I n most preferred embodiments, the overall shape of the conductor pattern is a geometrical one, preferably one of a square, a rectangle, a parallelogram, a tra pezium, an ellipse, and (most preferably) a circle. I n the lattermost case, it is to be noted that providing a conductor pattern which is su bstantially circular in appearance can be beneficial because a d roplet of liquid formulation applied over the excitation element will tend also to possess a generally similar and circular cross-sectional shape. I n most preferred embodiments, the application of liquid formu lation to the excitation element will be such that substantially the contact area of the droplet will lie entirely within the perimeter of the shape defined by the conductor pattern of the excitation element, because only in this case can it be assured that the entire droplet of formulation extant on the excitation element will be subject to excitation provided thereby. Most preferably, the excitation element will be of appreciably greater electrical resistance as compared to that of the contact portions, preferably as a result of the average width of the conductor in the excitation element being much reduced as compared to the width of the contact portions. Alternately, and depending on the method of fabrication of the excitation device, the excitation element may be constituted of a different material entirely from that of the contact portions, and preferably one which is significantly more electrically resistive.

I n an alternate embodiment, the contact portions and excitation elements may be metallic in nature, and applied and affixed to the su bstrate by means of a metallic vapou r deposition process, or yet further alternately, or possibly additionally, the substrate may possess or have applied thereto a metallic layer and be subject to an etching or other ablation tech nique such that the contact portions and excitation elements are both distinctly, clearly and separately defined and furthermore in electrical communication with one another. I n fu rther embodiments, the substrate may be structu rally multi-laminar and include at least one electrically conducting layer and at last one electrica lly insu lating layer, the latter being etched or otherwise ablated to reveal requisite portions of the u nderlying electrically conductive layer, as is well known in the manufacture of printed circuit boards (PCBs). I n a yet further embodi ment, the conducting contact portions and excitation elements may be stamped or otherwise compressed onto one surface of the substrate in a manner akin to a foil stamping operation whereby a pattern of a conducting foil may be transferred from a release pa per to the su bstrate.

Preferably, the material of which the su bstrate is constituted is will be a glass, further preferably a silicate, or a borosilicate, or a glass manufactu red using a soda-based or a lime-based precursor. The substrate dimensions will of course be selected according to the recess or cavity within the mouth piece of an inhalation device it is to occu py, but as an example, the substrate may be in the region of 1 -4mm thick, and of su bstantially quadrangu lar primary cross-section, preferably either rectangular or square, with dimensions of 3-1 5mm along either edge.

The skilled reader will appreciate from the foregoing that the excitation element and contact portions thereof are essentially applied directly to one surface of the substrate and therefore, after having been applied, an upper surface of both is essentially exposed, and it is over the exposed su rface of the excitation element that the formulation is applied so that there is direct physical contact between the formulation and the excitation element, and therefore the formu lation can interact with the excitation element, or at least those portion of it which are in contact with the formu lation, and thus the physical characteristics, most notably the electrical resistance (or possibly some other measurable physical property) will be altered as a result of this interaction. For example, the naked excitation element will perform differently when su pplied with an excitation energy as opposed to when there is an amount of formu lation extant over the surface of it, and it is one of the underlying tenets of the present invention that this performance difference, which will change progressively as increasing amou nts of the formu lation are aerosolised and thus removed du ring each excitation, can be advantageously utilised in a variety of different ways, as will now become apparent.

Thus, according to a second aspect of the present invention, there is provided a control circuit for an excitation device having been pre-dosed with an amou nt of an aerosolizable/vaporizable su bstance, wherein said control circuit is adapted to selectively and repeated ly provide an excitation energy to said excitation device which, when in a state of excitation, causes at least some degree of aerosolization/vaporisation of said substance, said control circuit comprising switch means for selectively activating said control circuit a nd thus energising said excitation device, first con nection means whereby said excitation device can be releasably con nected to said circuit a nd second con nection means whereby said control circuit is con nected to a sou rce of a suitable excitation energy, active measurement means whereby at least one physical characteristic of the excitation device may be measu red du ring energisation thereof, said physical characteristic being one which is at least partially dependent on one or both of the amount of substance at any time present on said excitation device, and the specific composition of said formulation as regards its constituents, and memory means for storing at least: recent historic measu rements of said physical characteristic of the excitation device currently connected to said control circuit, and

one or more profile data sets describing how the physical characteristic being measured changes for a specific excitation element depending on the amount of su bstance extant at a particu lar time on said excitation device, characterised in that the control circuit fu rther comprises adaptive control means whereby the energy supplied by the control circuit to the excitation device is regu lated in a predetermined man ner according to at least one of said stored profile data sets, said one profile data set being that which is determined by said adaptive control means as being most closely correlated to one or both of a current instantaneous measu rement of the said physical characteristic for the currently con nected excitation device, and one or more previous measu rements of said physical characteristics stored in said memory means for the currently connected excitation device and which was measured du ring the current or a previous activation of the control circuit.

I n one preferred embodiment, the regulation of the energy supplied by the control circuit to the excitation device is achieved either directly by the adaptive control means which will include energy regu lation means, or alternatively, the control circuit will additionally include separate energy regu lation means with which said adaptive control means communicates for the pu rposes of instruction and control thereof.

Preferably, the memory means stores both recent historic measu rements of the measured physical characteristic of the excitation device while being supplied with the excitation energy, and one or more profile data sets, most preferably multiple profile data sets representing the performance characteristics, in pa rticular as regards the one or more particular physical cha racteristics being measured by the control circuit, of multiple different excitation devices, each having been pre- dosed with a variety of different amounts of different su bstances. As will be appreciated by those skilled in the art, in the case where the memory means stores multiple different profile data sets, it may be necessary for the control circuit, and in particu lar the adaptive control means, to require multiple historic measurements, together with any instantaneous measurement available to it, before an effective correlation can be made with the stored profile data sets and a resulting one of those sets can be identified as being most representative of the operating characteristics of the currently connected excitation device. I n modern signal processing parla nce, a sufficient number of samples must be available to the adaptive control device before a specific profile data set can be identified and then selected as that according to which the excitation device, or more specifically the energy supplied to it, shou ld be subsequently regu lated and/or controlled. Most importantly, once a profile data set has been identified and selected in this manner, the control circuit then functions to deliver excitation energies to the excitation device for the current and preferably also su bsequent activations of the control circuit in a manner entirely or substantially prescribed by the selected profile data set. Thus, in one preferred embodiment, the memory means also maintains a record of the most recently identified and/or selected profile data set, and the control means performs an initial validation and or verification fu nction using one or only relatively few successive instantaneous samples of the measured physical characteristic to ensu re that this particular identified profile data set remains valid. I n alternative embodiments, and because the control circuit must in any event at some point always perform an initial correlation between sample data and the stored profile data sets, the control circuit may for any and all particular activations thereof, always perform the necessary correlation to identify the most appropriate profile data set for that current activation. I n this case, there would of cou rse be no need for the most recently used profile data set, or at least some indication thereof, to be specifically stored in the memory means.

I n preferred embodiments, the control circuit additiona lly includes a source of excitation energy, and most preferably this takes the form of a rechargeable battery, in which case the excitation energy is of course electrical in natu re. Most preferably the physical characteristic which is to be measu red, and which is thus representative of the cu rrent state of the excitation device as regards its specific type and the amou nt and nature of the su bstance currently extant thereon, is the electrical resistance.

Preferably the control circuit fu rther comprises indication means, which may be audible or visible or both, said indication means being caused to be activated by said control circuit when the adaptive control means makes a determination that the or a most recently or instantaneously measu red physical characteristic of the excitation device exists, at, proximate or beyond a terminal data point of the profile data set cu rrently selected and identified as being that most representative of the operating characteristics of the currently connected excitation device, and being used to regu late the energy su pplied thereto, said terminal data point within said profile data set being indicative or representative of the measu red physical characteristics of said excitation device when no substance is extant on the su rface thereof, or when the amount of active composition therein is su bstantially or totally depleted.

Preferably, the second connection means which connect the control circuit to the source of suitable excitation energy establishes a direct physical connection, and may take the form of wires or other simple electrical conduction means, tracks on a printed circuit board (PCB), or an electromechanical con nector, for example a plug and socket or other type of cooperating arrangement of parts whereby both physical and electrical connections are achieved simultaneously as one is connected to the other.

Fu rther preferably, the control circuit includes or is commu nication with one or more of: ambient air pressure, temperature, hu midity sensing means. The skilled reader will understand that these ambient properties can have a significant impact on any aerosol isation/vaporisation process, or indeed any other process wherein any substance or formulation is required to cha nge state, either from solid to liquid, or from liquid to a vapou r or gaseous phase. I n the particular case of aerosolisation of a formu lation, especially one containing an active ingredient such as nicotine, ambient properties such as these can have significant implications on the aerosolisation process, and it is further considered within the ambit of this invention that the values of one or more of said ambient properties be used by the control circuit, and in a particu larly preferred embodiment, a programmable element thereof, to apply one or more scalar, vector or functional correction factors to one or more, preferably all, of the value(s) of the instantaneously measured physical characteristic, the data within the reference profile data sets, and any stored value of the measured physical characteristic at some point earlier in time. As will be apparent from the foregoing, it thus desirable that any storage in memory means of anything measured by said control circuit be performed not on ly together with some indication of the time the measurement was taken, but also with some indication of the ambient air properties at the relevant time, and the third aspect of the invention below relating to a method of operating a control circuit should be considered similarly expanded to include this type of operation.

The skilled reader will u nderstand that the primary advantages of such a control circuit are at least twofold. Firstly, the control circuit is capable of effectively identifying the particular excitation device currently connected and, provided enough sample data are collected, the amou nt and indeed the actual constitution of a formu lation currently extant over the surface of an excitation element thereof, by comparing the sampled data with the previously stored "reference" profile data sets. Second ly, once an appropriate and representative profile data set has been selected as that which shou ld direct and characterise the ongoing operation of the control circuit, the control circuit can then dynamically adjust its ongoing operating characteristics according to the profile, and in turn the operating characteristics of the excitation device can be similarly dynamically altered - in effect, the control circuit is capable of controlling and regulating the energy supplied to the excitation device and thus can very effectively and accurately control the aerosolisation/vaporisation of the substance extant at any time on the surface of the excitation device according to both the appropriate profile data set, and the ongoing instantaneous measu rements being taken by said control circuit. This is of particu lar advantage where the excitation device is desired to aerosolise/vaporise a substance applied over its su rface, and in particular to aerosolise/vaporise a substance including an active ingredient such as nicotine such that the concentration of the active ing redient in the aerosol/vapour is maintained at a desired level, because the data in the profile data sets are likely to have mostly been empirically or experimentally determined and thus be la rgely incomplete, and precise adaptive control of the excitation device and the energy supplied to it according to the insta ntaneously measured physical operating characteristics will therefore require some interpolation and/or extrapolation, which the control circuit of the present invention is perfectly suited to perform. I n a third aspect of the present invention, there is provide a method of operating a control circuit as hereinbefore described including the steps of activating the control circuit to initiate the su pply of an excitation energy to an excitation device pre-dosed with an amou nt of an aerosolizable or vaporisable substance applied to a suitable surface thereof, said excitation energy being transmitted, in transmuted form as may be the case, from said excitation device to said substance to cause at least some aerosolisation or vaporisation thereof, said excitation energy being continued to be su pplied for as long as the control circuit remains activated,

repeated ly measuring at least one physical characteristic of the excitation device while activated, said physical characteristic being dependent, at least to some extent, on one of: the amount of su bstance extant thereon, and a concentration of a chemical constituent thereof, either or both of which may change progressively as the su bstance is aerosolised/vaporised,

storing a plurality of the measu rements arising from the preceding step, together with some indicator of time, cha racterised in that the control circuit performs the further steps of comparing a plurality of the previously stored time-dependent measu rements of the physical characteristic with corresponding data in one or more reference performance profile data sets substantially completely describing the time-dependent functional performance of excitation elements having amou nts of su bstance thereon in terms of the physical characteristic being measu red,

determining at least a particu lar one of said reference performance profile data sets, being that reference performance data set having data points which best fit the data having been most recently measu red and stored, and thus being at least partially representative of the amount of substance currently extant on the excitation device or a concentration of at least one chemical constituent thereof,

selecting the said particular one reference performance profile data sets as that according to which the control circuit should fu nction immediately upon and subsequent to said selection,

regulating the supply of excitation energy in accordance with the pa rticular reference profile data set selected so as to achieve a desired subsequent aerosolisation/vaporisation of the remaining amou nt of substance.

Preferably, the storing of the plu rality of measurements is one or both of: temporary or transient, in that the measurements are only stored for the current activation of the control circuit, and are discarded upon or immediately after de-activation, such storage for example occurring in volatile memory means, and

permanent, in that the measurements are stored in a memory which is accessible in both the cu rrent activation and a subsequent activation, such storage for example occurring in su bstantially non-volatile memory means.

Most preferably, the method includes the further steps of automatically terminating the current activation of the control circuit after a predetermined time, herein an activation du ration time which is preferably persistently stored and which is both u nchanged between, and accessible by the control circuit in, successive activations, has elapsed from the initiation of the current activation, determined, as may be the case either from the time-stamp for the first measurement of the physical characteristic for the current activation, or more simply directly from a time-stamp stored by said control circuit immediately upon any activation thereof.

Fu rther preferably, the method includes the further step of preventing, after any previous activation of the control circuit, the su pply of excitation energy to the excitation device un less and u ntil a predetermined amount of time has elapsed since the end of the previous activation determined, as may be the case, by comparing a current time or the time stamp of the most recently stored measu rement of the physical characteristic having occurred du ring the cu rrent activation with one of a time-stamp for the last measurement of the physical characteristic taken during the said previous activation and a simple time stored during said previous activation, and establishing whether the difference in those times exceeds an activation delay time value stored in a persistent man ner so as to be available to, and unchanging between successive activations of, said control circuit.

The reader will immediately understand that the above preferred method steps require that the control circuit be provided with appropriate clock means or other timing means, and therefore the statements of invention (and any claims) hereof may be appropriately extended to include such means as may be appropriate to facilitate such (and su bsequent) additional functionalities of the control circuit.

I n the case where the instantaneous measurements of the physical characteristic persist between activations of the control circuit, preferably the method of operation can be extended to provide a facility whereby the control circuit is capable of automatically recognizing, based on a comparison between one or more of the measu rements of the physical characteristics stored during a previous activation of the device, and one or more measurements of the said physical characteristic taken du ring the current activation, whether the excitation device currently connected to the control circuit is that which was con nected to the control circuit during said previous activation. The particular functionality can be readily achieved because the physical operating characteristics of an excitation device, including any amount of formulation thereon, as they were at the end of a previous activation shou ld, excepting exceptional circu mstances, be largely identical to those at the commencement of an immediately su bsequent activation because the amount of formulation extant on the excitation device will not change substantially between successive activations, especially when the time between successive activations is relatively short, for example of the order of only a few seconds, e.g. 1 -30s, because no aerosolisation of that amount of formulation will occu r when the excitation device is not energised. Of course, i n the event that the excitation device con nected to the control circuit during a previous excitation is or becomes spent in that any and all of the formu lation previously extant on the excitation device at the begin ning of that previous activation is aerosolised so that none or on ly negligible amou nts of the formulation remain, and that excitation device is swapped between activations for a new excitation device having a non- negligible amount of formu lation thereon, then the control circuit will immediately recognise, from the large discrepancy between the last measu red value of the physical operating characteristic and the most recent or instantaneously measured value thereof, that a new excitation device has been con nected, and its operating mode can be changed accordingly. I n this regard, the skilled reader will u nderstand that the control circuit can be largely self-sufficient and self-regulating.

From the above, it will also be u nderstood that the control circuit is also capable of determining when the currently connected excitation device is, or is about to become, spent, the method of operating the control circuit further preferably extends to include the steps of determining such a condition, and fu rther preferably commu nicating the existence of this condition to appropriate indication means as previously mentioned above. I n one preferred embodiment, the method includes the fu rther steps of establishing, from a comparison of one or more most recently measu red values of the physical operating characteristic of the excitation device and one or more corresponding values obtained from the currently selected reference performance profile data set whether the amount of formu lation extant on the excitation device is or is becoming neg ligible, such condition being indicated generally if there is little cha nge in that value between successive activations and/or if the last measured value is at or proximate a maximu m or minimum, or an initial or terminal, value of the characteristic within the reference profile data set. Further prefera bly, the method includes the further step, if the control circuit establishes the existence of this condition, of commu nicating the existence of such condition externally of the control circuit, for example by communicating with suitable indicating means as previously described.

For the avoidance of doubt, the following features shou ld be considered as preferable for any and all aspects of the present invention: the most preferable form of the excitation energy su pplied by the control circuit is electrical energy, which will preferably emanate and be supplied from a battery, most preferably a rechargeable one, and which will be fu rther preferably be substantially comprised of Lithium ion cells,

the most preferable form of the excitation device is one which includes both contact portions and one or more separate excitation elements, both of which are applied to one side of a chemically inert substrate material, the former being appropriately electrically con nected to the latter and also being sig nificantly more electrically conductive tha n the latter, such that each excitation element is essentially an electrically resistive heating element by means of which the supplied electrical energy is tra nsmuted to heat energy which in turn transferred to the amount of formulation extant thereon to cause aerosolisation thereof;

the material of which excitation element is made and the formulation, in particu lar the chemical constituents thereof, are preferably chemically inert as regards one another, but when they are in direct physica l contact, the formulation has a non- neg ligible effect on one or more measureable physical characteristics of the excitation device, most preferably the electrical resistance thereof;

the excitation device is initially, prior to any use thereof, pre-dosed with an amount of a formulation which includes nicotine as an active ingredient thereof, and which the excitation device is capable of aerosolising when the electrically resistive excitation element reaches a most preferred operating temperatu re of 125- 135 deg.C, most preferably 130 deg.C,

the excitation is most preferably supported and retained within a mouthpiece component adapted for releasable con nection to one end or side of an electronic in halation device which preferably includes one or more and preferably all of: the control circuit, the battery, the activation switch, and any ambient air sensing means which may be provided; most preferably the electrical connection between the excitation device within the mouthpiece component and corresponding electrical con nectors provided at the said end or side of the inhalation device is achieved both simultaneously with their intercon nection, and by means of a plu rality of so-called (well known) pogo pins provided at the said one end or side of said inhalation device and adapted to slide contactingly over and into their desired and correct position on the various contact portions provided on the excitation device;

the substrate material on which the contact portions and excitation element are provided most preferably possesses a low thermal conductivity and a low thermal diffusivity such that on the one hand the substrate fu nctions largely as a heat insulator and on the other hand, even when heat from the hot resistive excitation element does pass into the substrate material thus warming it, the su bstrate material also acts in a man ner which tends to locally contain such heat, or in other words, it prevents or at least restricts the diffusion of the heat it does possess throughout its body; by selecting the material of the su bstrate carefu lly, with these properties in mind, not only can the substrate be efficient in that the vast majority of heat from the excitation element passes directly into the amount of formulation extant thereon, and any heat which does pass into the substrate material remains largely localised immediately beneath the excitation element which provided that heat; in some preferred arrangements, the thermal conductivities, and further preferably the thermal diffusivities, of the formulation and the substrate material are specifically selected and/or desig ned, and in particular it is preferable that the thermal conductivity and/or diffusivity of the formu lation are at least one, preferably 2 and ideally 3 orders of magnitude g reater than that of the su bstrate material;

the excitation device, and most preferably each excitation element thereof, is preferably pre-dosed with an amou nt of formu lation sufficient to allow for repeated aerosolisations, preferably 4- 10, more preferably 5-9, and most preferably 6-8, which is most a kin to the nu mber of times a smoker will puff on a cigarette, pipe, cigarillo or other conventional combustible tobacco product; the formu lation will ideally be applied in an accurate computer-controlled fashion, for example by a computer-controlled printing or other suitable hig h-accuracy liquid application technique to ensure that the amou nts of formu lation which are applied are in precise registration with, and disposed directly over and above each and every excitation element present on any one excitation device; in most embodiments, the formulation will preferably be applied in liquid or semi- plastic solid form, and after application, certain preferred formulationss may completely or partially alter state (i.e. partly or totally solidify, or become increasingly viscous).

I n a fourth aspect of the invention, there is provided an inhalation device incorporating either or both of an excitation element as herein before described, and a control circuit as hereinbefore described. I n a further aspect of the invention, there is provided a method of operating such an inhalation device in which a control circuit as hereinbefore described is provided, and which is to be operated according to the method of operation thereof as also hereinbefore described.

Although the skilled reader might question

(a) whether it is possible to repeatedly aerosolise a liquid or solid, semi-plastic or other viscous formu lation applied to the excitation devices of the present invention with the required degree of consistency and accu racy as regards the active ingredient within said formulation, particularly when, after each aerosolisation, the volume of the formulation remaining after each aerosoliation will have inevitably and appreciably decreased, and

(b) whether a formu lation in a liquid or other state is sufficiently stable, both physically and chemically, after having been applied to excitation devices, so as to be capable of both remaining in position without appreciable fluid flow (which of course negatively affect the measu rements physical resistance of the excitation element which wou ld tend to indicate that less of the formu lation remained than was actually the case), and remaning chemically and constitutionally intact, when it is of cou rse possible that one or more of the constituents of the formu lation could be volatile and thus be prone to at least some evaporation, the applicants herefor have discovered, beneficially, that

(a) not on ly is repeated consisted aerosolisation possible, but that also that the aerosols thus produced can be accurately controlled in that within each aerosol, the required concentration of nicotine can be consistently and reliably achieved, and

(b) provided that the excitation devices are suitably packaged an inert atmosphere which is opened on ly immediately prior to use, a nd that that use occu rs within a reasonably time frame such as 0.5- 1 days, then the formulation applied to excitation devices in this manner can be both physically and chemically stable.

The skilled reader might also question whether, during aerosolisation, any formu lation extant on the excitation device in the liquid phase and in a state of excitation, for example being hot, might have a tendency to flow over and beyond the perimeter of the cu rrently energised excitation element. Applicants herefor have also discovered, again beneficially, that this is not the case to any material or substantial degree, and any formu lation not currently being aerosolised remains su bstantially in situ on the excitation element notwithstanding its current state of energisation. 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

Figures 1 A, 1 B 1 C respectively show a perspective view, side and end elevations of an excitation device according to the present invention,

Figure 2 shows a partial schematic plan view of the contact portions and excitation element as mig ht be applied to a modified excitation device according to the present invention,

Figures 3A, 3B 3C respectively show an inhalation device in assembled form, and the mouthpiece component of said in halation device in disassembled and assembled form,

Figure 4 provides a schematic cross-sectional view of the device of Figu re 3A taken along the line A-A in that Figure,

Figures 5A, 5B, 5C, 5D show schematically a single activation of the excitation device of Figures 1 A, 1 B, 1 C, and how an amount of a formu lation extant on said excitation device is aerosolised as a resu lt of said activation,

Figure 6 provides a schematic representation, in block diagra m form, of one embodiment of a control circuit according to the present invention.

Figure 7 is schematic graph representative of a plurality of data with a nu mber of different profile data sets which may be utilised in the method according to the present i nvention;

Detailed Description

Referring firstly to Figures 1A, 1 B, 1 C, there is shown an excitation device 100 indicated generally at 100 and comprising a cuboid substrate 102 of a su bstantially chemically inert material, such as a silicate, lime, soda or borosilicate glass material though of course other similarly chemically inert materials may be considered. Ideally, the su bstrate material is one which is also physically inert that it possess relatively low thermal conductivity, expansivity, emissivity, and diffusivity characteristics - most glasses fu lfil these requirements adequately. To provide some idea of the required dimensions of the excitation device, dimensions a, b, and c are shown, and ideally a and b are of the order of a 5-50mm, whereas the thickness dimension c is sig nificantly smaller, perhaps of the order of 0.5-5 mm. Su bstrate 102 possesses upper and lower su rfaces 104, 106 respectively, and over the u pper surface 104 is applied an electrical conductor indicated generally at 108 which comprises 2 distinct and separate portions, namely contact portions 1 10A, 1 10B, 1 10C, and excitation elements 1 12A, 1 12B in which the conductor follows a generally meandering but generally u niform (in that the conductor lengths within the pattern are rough ly equal) pattern similar to that of a well-known square wave. In the embodiment depicted, the excitation device comprises only two excitation elements 1 12A, 1 12B arranged adjacently at towards the end of the su bstrate remote from the contact portions, but of cou rse there could be easily be another number, e.g. 1 , 4, 6, 8, and where an even nu mber is provided, they would ideally be sized and arranged symmetrically of the substrate so that any heat transfer into the substrate resu lting from the energisation of the excitation elements would be largely similarly symmetrical, at least as regards one axis of symmetry of the underlying su bstrate. Ideally, the contact portions of the electrical conductor will be one or more orders of magnitude less resistive to the flow of electrical cu rrent than the excitation elements such that the temperature of the latter effectively rapid ly rises when a suitable electrical current is applied thereto throug h the contact portions. I n the terms of the man ner of application and affixing of the excitation element and its respective portions, and whether this is done in a single pass or in separate operations is beyond the scope of this application, suffice it to say that it is of course fundamental that the contact portions and the excitation element be electrically connected. Fu rthermore, althoug h the excitation device of Figure 1 is shown having a pair of excitation elements 1 12A, 1 12B, and three contact portions 1 10A, 1 10B, 1 10C, with contact portions 1 10A and 1 10C providing independently variable and or different electrical currents to respective excitation elements 1 12A, 1 12B respectively, each of which is con nected to contact portion 1 0B which wou ld act as a common g round in well known man ner, other arrangements are of equally cou rse possible, such as providing each and every excitation element with its own entirely independent pair of contact portions.

I mportantly as far as the present invention is concerned, each of the excitation elements 1 12A, 1 12B is pre-dosed with a suitable amount of an aerosolisable formulation ideally including at least one active ingredient, such as nicotine. I n the Figu re, such pre-dosing is manifested in the at least partial, and preferably substantial covering of each excitation element with respective g lobules 1 14 A, 1 14B of said formulation, which can thus be su bsequently aerosolised by the underlying excitation elements when they become energised. Globules 1 14A, 1 14B can be more clearly seen in Figures 1 B, 1 C. Also to be noted from the Figures is that globu les 1 14A 1 14B are entirely separate from one another, as befits the independently controllable excitation elements said globules substantially overlie. Such separation of the globules is a preferable feature of the invention, although it is of course possible to apply only a single globule of formulation over substantially the entire area occupied by both excitation elements, particularly if the excitation elements are controlled in unison, or combined into only a single excitation element (in which case common ground contact portion 110B would not of course be required).

Referring briefly to Figure 2, there is shown one possible alternate embodiment of an excitation device 208 wherein the excitation element 212A connected between contact portions 21 OA, 210B is approximately circular as shown by and within dotted line 220. When it is considered that a globule, particularly of a liquid or semi-plastic solid, will generally have a similarly circular perimeter, the provision of a circular excitation element such as that shown in Figure 2 may prove significantly more efficient, both in terms of the transfer of excitation energy to the superimposed globule of formulation, and also in terms of the accuracy of the feedback measurement of the physical characteristic of the excitation element and extant formulation superimposed thereon (being indicative of the volumetric quantity of said formulation extant at the instant of measurement). As can be seen, by comparison, in Figure 1 A, there are areas of the (essentially square or rectangular) excitation elements which lie outwith the contact perimeter of the globules, are therefore largely redundant and thus only contribute to operational inefficiencies.

Turning now to Figure 3A, there is shown an inhalation device 300 according to one embodiment of the present invention comprising a main body part 302 and a mouthpiece component part 304. The mouthpiece component 304 is releasably attachable to the main body part 302 such that it can be easily disconnected, both physically and electrically, from the body 302 and quickly disposed and/or exchanged. Furthermore, the mouthpiece component 304 may comprise first and second parts 304A, 304B respectively which in some embodiments may be separable as more clearly seen in Fig.3B. The first part 304A, and in particular a free end 304A-A thereof, is that around which a user's lips (not shown) are pursed during usage of the inhalation device, and as a result of a suction pressure applied at that free end by the user's mouth while the user's lips are so pursed, air is caused to flow through and within the mouthpiece component from an air inlet 304B-B provided in the second component towards and eventually out through an opening (not shown) provided at the extremity of the said free end 304A-A.

Figure 3B shows the mouthpiece component 304 in disassembled form. One or other, and preferably both first and second parts 304 A, 304B will internally define a horizontal recess of a size appropriate to receive an excitation device 100 according to the present invention. Furthermore, preferably, first and second parts will include one or more internal detents (not shown) within said recess by means of which the excitation device is retained within said recess in both the correct position and orientation as regards an air flow guidance formation indicated generally at 306 which functions to ensure that air flowing through and within the mouthpiece component from the air inlet 304B-B towards the extremity of the free end 304A-A of the first part 304 A is guided internally of the mouthpiece component immediately above and over the excitation device 100, and most importantly immediately above and over globule(s) 114 A, 114B which, if the device is currently in an active state, will be being aerosolised as a result of the heat being applied by the excitation elements underneath them at that instant. The aerosol being thus produced will therefore be automatically entrained in the air flow and automatically be delivered as part of it into the user's mouth.

Finally as regards Figure 3B, first and second parts 304A, 304B are also provided with protrusions 308, 310 respectively which cooperate with corresponding recesses (not shown) provided in the alternate component so as to enable the first and second parts to be connected together in snap- fit manner, and in some embodiments, releasably so. Second part 304B additionally may contain protrusions 312 which enable secure connection of that part, and thus the mouthpiece component when assembled to the body 303 of the device as fu rther explained below.

As can be seen in Figure 3C, when the first and second parts 304A, 304B are assembled, the excitation device 100 will be securely retained within the mouthpiece component 304, and in the correct disposition as regards the airflow guidance formation (not shown in Figure 3C) disposed immediately above it. Also seen in this Figure is one end of the body 302 of the inhalation device and to which the mouthpiece component is to be connected, in some embodiments by means of cooperating projections 312, 314 provided on the second part 304B and body 302 respectively. The body 302 is additionally provided with an electrical connection arm 320 which projects beyond the end of the body 302 and which is designed so as to be substantially completely received within a corresponding recess (not shown) within the second part 304B during and on completion of the attachment of that part, and thus the mouthpiece component to the body. As a result of this attachment, a plurality of electrical connectors 322, being of suitable number and arrangement and provided on the lowermost surface of the connection arm 320 are brought into contacting relationship with all the appropriate contact portions (not shown) of the excitation device 100. Thus, when the mouthpiece component is completely attached to the body, all the correct electrical connections are automatically made with the between the electrical connectors 322 and the contact portions of the excitation device. In preferred embodiments, the electrical connectors 322 may be spring-loaded so they can be resiliently deflected in a vertical or other direction during the attachment process, and most ideally said electrical connectors are pogo pins commonly used in electrical connections of this type.

Figure 4 shows a cross-section through inhalation device 300 along the line A-A in Figure 3 A. Mouthpiece component 304 containing an excitation device 100 is connected to main body part 302. The excitation device 100 shown in this Figure is a slightly modified version of that shown in Figure 1 A, because it is provided with 4 discrete excitation elements, arranged in 2 rows of 2 as can be seen in the Figure, the forward-most of these two being referenced as 112A, 114A and 112B, 114B respectively, such referencing of course representing both the relevant excitation element and the globule of formulation applied over it. Also seen more clearly in this Figure is the electrical connection arm 320 and the arrangement and number of the electrical connectors 322 which of course are required to electrically connect the excitation device 100 to the control circuitry (not shown) provided in the body 302.

Ideally, the main body 302 has a first interior space 402 for accommodating an electric power source, ideally a rechargeable battery (not shown) and a second interior space 404 for containing a control unit (not shown) for controlling electrical activation of the excitation elements (112 A, 112B). Electrical contacts 322 are connected to the electric power source via the control unit. An activation button 406 is also provided on the main body part 302 to enable a user to activate the control circuit, which in turns will initiate and maintain (for as long as the button is depressed) the supply of electrical energy from the battery through the control circuit, into the electrical contacts 322 and thence into the excitation device itself through the contact portions thereof so that the excitation elements will heat up to operating temperature, ideally quite rapidly (< 1 -2s, preferably < < 1 -2s). In some embodiments, activation of the control circuit may be achieved by sensing means provided in an appropriate location, either interiorly or exteriorly on one or other part of the mouthpiece component, and which are adapted to sense either to the pursing of a user's lips around the free end of the first part 304 A, or alternatively the initiation of a flow of air through the mouthpiece component, this being indicative of the user applying a suction pressure to the device immediately prior to or in conjunction with an inhalation.

It may also be seen from Figure 4 that the air flow guidance formation 306 of the second part 304B is provided with a pair of air flow channels 306A which cause air drawn in through the inlet (not shown) to flow in an essentially linear manner through said channels over and importantly immediately above the excitation elements and globu les of formu lation which overlie them, 1 12A, 1 14 A, for the reasons already described. When air flowing within these chan nels ultimately emerges from them, provided the in halation device has been activated, it will contain and carry the required amount of an aerosol of the formu lation applied to the excitation device. I n order to created desired fluid flow conditions within said channels, at the appropriate position, for example immediately before, after or immediately above a respective pair of excitation elements, the channels may include interior formations (not shown) such as Ventu ri-effect inducing constrictions or other suitable formations which may assist the entrainment of the aerosolised formu lation in the airflow.

It is to be noted that the inhalation device 300 of Figu res 3-4 is configu red to be highly accu rate in terms of the amount of the active ingredient (most preferably nicotine) present in the formulation which is aerosolised along with the other constituents thereof. I n short, it is high ly desirable that, regardless of the amount of formu lation extant on the surface of the excitation elements, any activation of the device causes the creation of an aerosol which contains precisely the desired concentration of the active ingredient. Devices which are capable of performing repeatedly in this man ner are capable of complying with the medicines and healthcare regulatory frameworks implemented in the majority of the developed world. In the U K at least, where the regulator body responsible for the approval of medicines and human treatments is the Medicines and Healthcare products Regu latory Agency (M H RA), an inhalation device approved by this body and functioning to deliver nicotine in a precisely controlled fashion as is now achievable by the present invention may be advertised and sold as a "nicotine replacement therapy".

As regards the specific composition of the formu lations considered as being within the scope of the present invention, the following example formu lations have been suggested:

i. Glycerol Formulation: 50% wt Nicotine, 50% wt Glycerol

ii. Xanthan Gu m with G lycerol: 50% wt Nicotine, 45% wt Glycrol, 3.75% wt Water, 1.25% wt Xantha n Gu m

iii. Porpylene Glycol: 50% wt Nicotine, 50% wt Propylene G lycol

iv. Propylene Glycol with Xanthan Gu m: 50% wt Nicotine, 45% wt Propylene G lycol, 3.75% wt Water, 1.25% wt Xanthan Gum

v. Glycerol with Menthol: 50% wt Nicotine, 45% wt Glycerol, 5% wt Menthol

vi. Propylene Glycol with Menthol: 50% wt Nicotine, 45% Propylene G lycol, 5% Menthol Ideally, the specific amount of any of the above formulations which is applied, in terms of the weight of any one globule thereof applied over one of the excitation elements, is of the order of 1 -2mg, preferably about 1 mg, which may be represented in volumetric terms having regard to the average densities of the said formulations, which are in the range of 1.0 g/cm 3 to 1.5 g/cm 3 .

Referring now to schematic Figures 5A, 5B, 5C, 5D, an excitation device 100 is shown on the surface of which has been applied a globule 114A of a formulation to be aerosolised and which is thus is direct physical contact with an electrical conductor 108 as previously described. Globule 114A overlies the excitation element portion of electrical conductor 108, which is shown in the figures as being electrically connected to a control circuit 500 consisting schematically of at least a switch 502 and a source of electrical power, in essence a battery, 504. In the state shown in Figure 5 A, the switch 502 is open, and thus the excitation device 100 is inactive. In Figure 5B, switch 502 is closed, and electrical current flows from the battery into the excitation device and ultimately to the excitation element, causing a rapid heating thereof to a desired temperature, in some embodiments around 130 deg.C. When the excitation element becomes hot, heat is transferred directly into the globule 114A to such an extent that it causes a rapid shift in the equilibrium vapor pressure above the uppermost surface of the globule 114A such that there is a concomitant increase in the vapourisation of at least some of the constituent component compositions present within the formulation from its uppermost surface, indicated generally at 506. In addition to this increase in vapourisation, there may be other constituent component compositions present within the formulation which, although inevitably undergoing a shift in their equilibrium vapour pressure, may not be entirely or even partially vapourised in the same manner or to the same extent as other compositions present within the formulation, but which may nevertheless still be promoted from the globule into the air above it along with other vapours. In the particularly preferred embodiment where the active ingredient present in the formulation is nicotine, and the maximum temperature of the excitation element driving heat into the globule is 130 deg.C which is significantly below the boiling point of nicotine at 247 deg.C, nicotine can nevertheless be promoted along with one or more of the other and significantly more volatile compositions present in the formulation, and furthermore at precisely and accurately controllable concentration levels. Thus what is created immediately above the hot globule of formulation is considered herein as an aerosol consisting of both vapours of the more volatile constituents of the formulation as well as a colloidal or other type of suspension or dispersion of droplets or other particles of the less volatile constituent components of said formulation, and the terms "aerosolisation" and other cognate terms should be interpreted accordingly. In some preferred embodiments, and depending on the particular nature and constituent composition of the formulation, the globule thereof may actually begin to boil, releasing yet further vapours of the more volatile constituents of the formulation from its uppermost surface, and yet further increasing the promotion of other less volatile constituents. Depending on the viscosity of the formulation, an effect similar to that exhibited by natural geysers may occur. At substantially the same time as this is occurring, or immediately prior to or subsequent to the activation, a user will apply a suction pressure at the free end of the mouthpiece component (not shown) which will in turn initiate an air flow indicated generally at 508.

In terms of the aerosol created during the activation, its constituent chemical composition and its physical properties may also depend, at least to some extent, on potentially many factors, most notable of which are: the temperature of the excitation element, the temperature gradient within the globule as well as the rate of change thereof, one or more ambient properties of the ambient air surrounding the globule, such as temperature, pressure, and humidity, as well as (possibly) the concentration and nature of any impurities in that air, as well as the flow velocity of that air induced as a result of user-applied suction. Notwithstanding these variables, and by virtue of the precise feedback-based electronic control of the excitation element and most particularly its temperature as will be further described below, the present invention can reliably deliver a consistent aerosol in which the concentration of an active ingredient such as nicotine is both remarkably consistent between activations.

In Figure 5C, the excitation device remains active, and the globule 114A of formulation continues to be appropriately and precisely heated, but in this case, aerosol 506 is shown as having now been entrained in the airflow 508 such that it is now carried thereby for ultimately delivery to a user as part of an inhalation he or she will subsequently perform.

Finally, in Figure 5D, the excitation device is shown as having returned to a passive state in which the switch 502 has been reopened, no current flows to or through the electrical conductor 108 or the different portions thereof, the substrate 104 of the excitation device, the electrical conductor 108, and in particular the excitation element portion thereof, and the remaining globule of formulation extant thereon are all allowed to cool, and the excitation device as a whole thus returns to steady state conditions. Of course, after every activation, a certain quantity of the globule of formulation will be lost to the atmosphere as a result of the forced aerosolisation which occurs during such activations, and therefore in the Figure globule 114A appears smaller than that appearing in "pre-activation" Figure 5A. This is important, because the amount of heat now required to heat the reduced size globu le 1 14A shown in in Figu re 5 D wil l inevitably now be less than that was required for the pre-activation globule shown Figure 5A, and therefore the characteristics of each activation, for example in terms of the heat applied by the excitation elements, will need to be different for each successive activation, and this will depend entirely on the volumetric quantity of formu lation extant on the excitation device at the time any such activation is commenced. Thus, the invention additiona lly provides a suitable control circuit and method of control thereof which overcomes this particu lar issue, and as will now be more fu lly described.

Referring now to Figu re 6, there is schematically depicted a control circuit indicated generally at 600, the various components of which are shown as fu nctional blocks, and which in one embodiment at least may include an activation switch 602 which may be mechanical, electromechanical, or purely electronic, and which serves to connect or disconnect an electrical power source 604 with a an excitation device 100 according to the present invention and as previously described. Switch 602 is currently shown in a disconnected or de-activated state, but when activated or connected, electrical cu rrent is permitted to flow between the power source 604 and excitation device 100 u nder the control of a control u nit 606 which may communicate directly with said power sou rce via control line 610 to effect such control. Excitation device 100 will preferably be releasably connectable to said control circuit as previously described so as to be capa ble of being exchanged when spent (i.e. when no, or only a neg ligible, un-detectable amount of formulation remains), and therefore excitation device 100 is not to be considered as forming part of the control circuit, even although said control circuit cannot fu nction properly without fi rst con necting an excitation device as such con nection effectively completes the electrical circuit required before any activation of the control circuit can occur. Also, as regards the con nection of the control circuit to the excitation device, although such connection is represented in Figure 6 by on ly a pair of conductors 604A, 604B, the skilled reader will of course understand that a different nu mber of such conductors may be required depending on the configu ration of the excitation device, in particular generally corresponding to the nu mber of excitation elements provided on said excitation device, which will in tu rn generally dictate the number of separate contact portions provided thereon. Also, in the case where an excitation device comprises multiple excitation elements, and some or all of these excitation elements are to be controlled independently, then the electrical connection of the excitation device to the control circuit may be correspondingly more complex, but for the purposes of clarity and simplicity, the reader is to u nderstand that Figu re 6 and the description provided in relation thereto is considered to be representative of all such possible con nections and arrangements, and the functionality of the various components of the control circuit may easily be extended to cover more complex connection configurations. I mportantly, control circuit 600 further includes measu rement and/or feed back circuitry 612 disposed between conductors 604A, 604B for actively measu ring one or more of the electric, electronic, or other physical characteristics of the excitation element during any activation thereof when it is being supplied with power. Preferably the characteristic which will be measured will be the instantaneous electrical resistance (Ω) of the excitation device, which may either directly measured or derived from the instantaneous measu rements of the electric current flowing into and out of the excitation device th rough conductors 604 A, 604B, and the electric potential drop between them. As previously mentioned, such measurement, particularly if taken frequently or periodically, can provide a good indication of, most preferably, the volumetric quantity of formu lation extant on the surface of the excitation device, if any, and also (possibly) the type of formu lation cu rrently in use, as well as the type of excitation device currently in use. For example, where multiple different types of excitation device are capable of being connected to the control circuit, and multiple different formu lations, in terms of their component constituents, may be applied to said excitation devices, then repeated hig h-frequency sampling of the instantaneous values of, for example, the electric resistance can provide a relevant indication to the control circuit, which can then adapt accordingly, as will be fu rther explained below. I n any event, any measurement of the instantaneous characteristic or property of the excitation device is communicated, at 614, to the control u nit 606 which is adapted, prog rammed or otherwise configu red to dynamica lly change the supply of power to said excitation device in response thereto so as to ensure a consistent aerosolisation of whatever amount of whatever type of formulation is determined by said control circuit as being extant on the surface of said excitation device.

I n order that the control circuit can achieve such dynamic control, the control circuit may additionally comprise either or both of volatile and non-volatile memory 616, 618 respectively, the control u nit 606 being in direct commu nication with each as required, and fu rthermore, in particularly advanced embodiments, the control circuit may fu rther include ambient air measu rement means 620, again in direct commu nication with the control unit 606.

Also provided as part of the control circuit is a clock or timer 622 capable of providing an indication of time to the control unit 606 and whereby said control u nit, in conjunction with historical data stored in either memory 616, 618 relating to either a cu rrent or a previous activation, can establish various parameters necessary for effective operation. Also, said clock can provide a suitable time- stamp to said control circuit when storing measu red data so that such data is stored capable of being queried in historic fashion. Finally, in order that the control circuit can provide some indication to a user of, for example, an alarm condition, the control u nit 606 is in commu nication with an indicator 624, which may be a simply a light.

A typical activation of the control circuit will now be described with reference to Figures 6 and 7.

Activation of the control circuit commences when, typically, a user depresses the switch 602, such action being immediately recog nised by the control u nit 606, which, in certain embodiments, may either be permanently connected to and powered by the power source 604, or alternatively the depressing the switch may initiate only the su pply of electrical power to said control unit, which then subsequently and separately effects and controls the delivery of power to the excitation device 100. I n any event, once the control circuit is so activated, a first step in the operation may be for an instantaneous time measurement from clock 622 to be taken and stored in, preferably, the volatile memory 616. Once the control u nit is in possession of a current time, the volatile or non-volatile memories 616, 618 may be queried to establish an elapsed time since the immediately previous activation. If this elapsed time is insufficient as compared to an activation time delay value stored ideally in the non-volatile memory (typically a time in the range of 3-8s is required between successive activations to allow the excitation element and formu lation thereof to retu rn to cool sufficiently), then the control u nit enters a wait cycle until such time has elapsed.

I n a second operation, the control circuit may take instantaneous measu rements of one or more of the ambient air properties by interrogating the ambient air measu rement mea ns 620 (if present) and temporarily storing such measurements in the one of the memories 616, 618. The control unit may then effect a comparison between such measurement and any recent similar measurement or other more static data as to whether the ambient conditions are within the standard operating parameters for the control circuit, or whether u nusual ambient conditions prevail which wou ld necessitate the control u nit performing some additional compensatory actions. Assuming for the time being and for simplicity that ambient conditions are not unusual, then the next operation may be for the control circuit either to commence the supply power from the battery to the excitation device if such has not already commenced, and then to retrieve an initial measurement from the measurement circuitry 612, which will then be immediately time-stamped and stored in either or both of the memories 616, 618. This initial measurement can, in certain embodiments, be compared by the control u nit with the last stored similar measu rement from a previous activation having been stored in non -volatile memory, and if the measurements are approximately the same, then this comparison would indicate that the excitation device present du ring the previous activation is still con nected to the control circuit for the current activation. Alternately, any large discrepancy between the previous and current measured values would indicate that some significant change had occu rred, most probably that the excitation device previously used had been exchanged for a new one. I n this event, any historical measured data stored from previous activations would be invalid and would be immediately discarded, and the control unit wou ld continue operation as if no such historic measu red data was available. I n any event, the next operation of the control unit may be to take one, two, th ree or possibly more fu rther measurements from the measu rement circuitry, each of which will be immediately time-stamped and stored in either or both of the memories 616, 618. If there is no or on ly negligible change between the initial measu rement value and one or more of the subsequently measu red values, the control circuit may, in certain embodiments, determine that no formu lation remains extant on the connected excitation device and either or both of suspend the power supply to the excitation device, and issue an alarm signal to the indicator 624, which would then be activated.

Provided that the control circuit establishes that there is an amount of formulation cu rrently extant on the excitation device, and now that the control circuit is in possession of sufficient sample data, the next operation performed is the comparison of that sample data against the data within one or more profile data sets stored in non -volatile memory 618, such being essentially a characterisation of how the values of the measured physical characteristic for excitation elements vary over time. As will be u nderstood, said profile data sets are essentially simple graphs as depicted in Figu re 7.

I n this Figure, fou r separate curves F1 , F2, F3, F4 are shown, each essentially representing, for four different formulations, how the resistance (R, Ω) of one particular type of excitation device (or excitation element) changes over time (t) that electric power is delivered to that device. Of course, after a certain amount of time, all of the formulation will be aerosolised and none will remain, after which the resistance of the excitation element will remain essentially constant, and hence it can be seen from the Figure that each curve eventually reaches a constant resistance value. What is less immediately obvious is that each profile data set or cu rve will have been created empirically or experimentally based on a standardised initial volume of formu lation, which wou ld of course exist at t=0, or before any aerosolisation thereof had occurred. There may be many cu rves, representing (possibly) not only different formulations and volu metric quantities thereof, but also different types of excitation device (heating, u ltrasonic, ionic etc.), and having differing numbers of excitation elements. Thus provided with at least two (and preferably more) recently measured historic data values of resistance, the control circuit ca n firstly effect a mapping operation to determine which of the curves F1 -F4 most appropriately fits the measured data, and then once an appropriate set of data has been identified and selected, an interpolation and/or extrapolation operation can then be effected using the standardised volume value represented by the curves, as modified by where on that particular curve the instantaneously measured data appear. For instance, if instantaneously measured values of resistance P1 and P2 were available to the control unit, P2 being later in time than PI by an amount At, then the control unit could establish readily that such points best fit curve F4 in Figure 7. Of course, there may be many 10s or hundreds of possible curves or profile data sets, and the more sample data available to the control unit, the better the fit of such dfata which can be achieved. Once a best-fit has been obtained and a particular curve or profile data set is identified, not only is this curve capable of providing an indication to the control unit as to the specific nature and composition of the formulation currently being used, but also the specific data points provide a precise indication to the control circuit of the volume of that formulation remaining. Indeed, it is a relatively simple matter for the control unit to calculate the current volume of formulation remaining, assuming of course that the curves in Figure 7 were all based on a standard initial dose amount of, say 1mm 3 , should such be required.

Perhaps most importantly for the present invention, the identification and selection of the most appropriate or "best-fit" curve also subsequently dictates, possibly after the control unit performs a further look-up operation for the corresponding operation profile data set, as to how the excitation energy should be supplied to the particular excitation device currently connected for the current activation so as to ensure correct, reliable and consistent aerosolisation of that amount of formulation which is currently extant thereon. Thus the supply of that excitation energy, most commonly electrical power, is actively and dynamically controlled during the activation, both in terms of magnitude and, in certain circumstances, profile.

In addition to the above operations, the control circuit may additional perform a perpetual timing operation during the current activation to ensure that it does not extend beyond a maximum activation time period value again stored ideally in the non-volatile memory. In the event that the current activation time is longer than the stored value, then the control circuit may immediately halt the current activation, either by suspending the delivery of power to the excitation device or by forcibly opening the switch 602 if electromechanical, with essentially the same result.

It will also be seen from Figure 7 that curve F1 has an analogue curve Fi x shown as a dotted line translated which is translated slightly upwardly of curve F1. This curve represents the performance of the particular formulation and excitation device represented by curve F1 at conditions other than ambient, for example if the one or more of the ambient humidity, temperatu re or pressu re as determined by ambient air measurement means 620 were different by some threshold value stored in memory from standardised values thereof. I n such case, the control circuit wou ld automatically apply some functional correction, for example the upward translation of cu rve F1 shown in Figure 7, and then any curve fitting of current data samples from the cu rrent activation would be against curve Fi x. I n this man ner the control circuit could automatically adjust for variations in ambient conditions.

Once the switch 602 is released and by whatever means, the power supply to the excitation device is immediately interrupted, and the excitation device, in particular the excitation elements thereof immediately begin to cool, as does any formu lation remaining extant thereon, and the system as a whole returns, relatively quickly (typically after 3 -4s) to steady state conditions after which a su bsequent activation ca n be commenced.