WO2023031197A2

WO2023031197A2 - Cartridge comprising a thermo-chromatic and thermo-conductive element

Info

Publication number: WO2023031197A2
Application number: PCT/EP2022/074080
Authority: WO
Inventors: Rui Nuno BATISTA; Serge LOPEZ
Original assignee: Philip Morris Products S.A.
Priority date: 2021-08-31
Filing date: 2022-08-30
Publication date: 2023-03-09
Also published as: EP4395582A2; US20240358072A1; JP2024530273A; WO2023031197A3; KR20240058119A; CN117835849A

Abstract

A replaceable cartridge is provided. The replaceable cartridge comprises a liquid storage portion comprising a liquid aerosol-forming substrate. The replaceable cartridge comprises a vaporiser configured to vaporise the liquid aerosol-forming substrate. The replaceable cartridge comprises a thermo-chromatic and thermo-conductive element in thermal contact with the vaporiser, the thermo-chromatic and thermo-conductive element having a temperature threshold beyond which the thermo-chromatic and thermo-conductive element performs a chromatic change.

Description

CARTRIDGE COMPRISING A THERMO-CHROMATIC AND THERMO- CONDUCTIVE ELEMENT

The invention relates to cartridges in which an aerosol is generated by vaporising a liquid aerosol-forming substrate using a vaporiser and to aerosol-generating systems comprising such cartridges.

One type of aerosol-generating system is a system that operates by heating a liquid aerosol-forming substrate to produce a vapour. Such liquid is normally referred to as e-liquid. The vapour then cools to form an aerosol. Most systems of this type use some form of liquid retaining material, such as a wick, to hold the liquid aerosol-forming substrate and typically deliver it to a heating element. However, as the amount of liquid aerosol-forming substrate decreases and the liquid retaining material dries out, less liquid is delivered to the heating element, which may result in a smaller amount of aerosol being delivered and may lead to the heating element being overheated. Also, as the liquid retaining material dries out, it is more prone to charring or burning. This can lead to undesirable compounds in the generated aerosol. This may also generate burning smells or unpleasant flavours. Likewise, a user may refill an unknown e-liquid into the empty cartridge, which may result in contaminating the cartridge by using non-compliant e-liquids.

Cartridges and aerosol-generating systems that comprise a protection against overheating and refilling with non-compliant e-liquids are known. However, this kind of protection may lead to an increase in the cost of the cartridge and the system. It would be desirable to provide a cartridge and an aerosol-generating system that may overcome at least some of the above shortcomings in an efficient and inexpensive manner.

A replaceable cartridge may be provided. The replaceable cartridge may comprise a liquid storage portion comprising a liquid aerosol-forming substrate. The replaceable cartridge may comprise a vaporiser configured to vaporise the liquid aerosol-forming substrate. The vaporiser may comprise a wick configured to absorb the liquid aerosol-forming substrate. The replaceable cartridge may comprise a thermo-chromatic and thermo-conductive element in thermal contact with the vaporiser, the thermo-chromatic and thermo-conductive element having a temperature threshold beyond which the thermo-chromatic and thermo-conductive element performs a chromatic change. The replaceable cartridge may comprise a cartridge air inlet. The replaceable cartridge may comprise a cartridge air outlet, the cartridge air inlet and the cartridge air outlet being arranged to define an air flow route between the cartridge air inlet and the cartridge air outlet, the cartridge air outlet being configured to allow the exit of vaporised liquid aerosol-forming substrate.

A replaceable cartridge may be provided, the replaceable cartridge comprising:

- a liquid storage portion comprising a liquid aerosol-forming substrate; - a vaporiser configured to vaporise the liquid aerosol-forming substrate, the vaporiser comprising a wick configured to absorb the liquid aerosol-forming substrate;

- a thermo-chromatic and thermo-conductive element in thermal contact with the vaporiser, the thermo-chromatic and thermo-conductive element having a temperature threshold beyond which the thermo-chromatic and thermo-conductive element performs a chromatic change;

- a cartridge air inlet;

- a cartridge air outlet, the cartridge air inlet and the cartridge air outlet being arranged to define an air flow route between the cartridge air inlet and the cartridge air outlet, the cartridge air outlet being configured to allow the exit of vaporised liquid aerosol-forming substrate.

As used herein, the term “replaceable cartridge” refers to a cartridge that may not be refillable. Thus, when the liquid in the liquid storage portion has been used up, the cartridge must be disposed of. The cartridge can then be replaced with a new cartridge in the aerosolgenerating system.

Since the cartridge is replaceable, the risk of refilling the liquid storage portion with a liquid aerosol-forming substrate of inferior quality is minimised.

As used herein, the term “aerosol-forming substrate” relates to a substrate capable of releasing volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate.

The liquid aerosol-forming substrate preferably has physical properties, for example boiling point and vapour pressure, suitable for use in the cartridge. If the boiling point is too high, it may not be possible to heat the liquid but, if the boiling point is too low, the liquid may heat too readily.

The liquid aerosol-forming substrate may comprise nicotine. The nicotine containing liquid aerosol-forming substrate may be a nicotine salt matrix. The liquid aerosol-forming substrate may comprise plant-based material. The liquid aerosol-forming substrate may comprise tobacco. The liquid aerosol-forming substrate may comprise homogenised tobacco material. The liquid aerosol-forming substrate may comprise a non-tobacco-containing material. The liquid aerosol-forming substrate may comprise homogenised plant-based material.

The liquid aerosol-forming substrate may comprise at least one aerosol-former. An aerosol-former is any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol. Suitable aerosol-formers are well known in the art and include, but are not limited to: polyhydric alcohols, such as triethylene glycol, 1 ,3-butanediol and glycerine; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Aerosol formers may be polyhydric alcohols or mixtures thereof, such as triethylene glycol, 1 ,3-butanediol and glycerine. The liquid aerosol-forming substrate may comprise other additives and ingredients, such as flavourants.

The liquid aerosol-forming substrate may comprise water.

The liquid aerosol-forming substrate may comprise nicotine and at least one aerosol former. The aerosol former may comprise glycerine. The aerosol-former may comprise propylene glycol. The aerosol former may comprise both glycerine and propylene glycol. The liquid aerosol-forming substrate may have a nicotine concentration of between about 0.1 percent and about 10 percent.

The cartridge may comprise a liquid storage portion for storing the liquid aerosolforming substrate. An advantage of providing a liquid storage portion is that the liquid in the liquid storage portion is protected from ambient air (because air cannot generally enter the liquid storage portion), light or both air and light, so that the risk of degradation of the liquid is significantly reduced. Moreover, a high level of hygiene can be maintained.

The liquid storage portion may have a capacity of between about 1 ml to 5 ml.

The vaporizer of the replaceable cartridge may comprise a wick for absorbing the liquid aerosol-forming substrate.

The wick may be arranged to be in contact with the liquid aerosol-forming substrate in the liquid storage portion. The wick may extend into the liquid storage portion. The liquid aerosol-forming substrate may have any suitable physical properties, including surface tension and viscosity, which allow the liquid to be transported through the wick by capillary action or by any other physical principle.

The wick may be a capillary wick designed for conveying the liquid aerosol-forming substrate by capillary action. When the wick is a capillary wick, the wick may have a fibrous or spongy structure. The capillary wick may comprise a bundle of capillaries. The capillary wick may comprise a plurality of fibres or threads or other fine bore tubes. The capillary wick may comprise sponge-like or foam-like material formed into a rod shape. The structure of the capillary wick may form a plurality of small bores or tubes, through which the liquid can be transported by capillary action. The capillary wick may comprise any suitable material or combination of materials. The suitable materials may be capillary materials, such as a sponge or foam material, ceramic- or graphite-based materials in the form of fibres or sintered powders, foamed metal or plastics material, a fibrous material, for example made of spun or extruded fibres, such as cellulose acetate, polyester, or bonded polyolefin, polyethylene, terylene or polypropylene fibres, nylon fibres or ceramic. The capillary wick may have any suitable capillarity and porosity so as to be used with liquid aerosol-forming substrates having different physical properties. The liquid aerosol-forming substrate may have physical properties, including but not limited to viscosity, surface tension, density, thermal conductivity, boiling point and vapour pressure, which allow the liquid to be transported through the capillary device by capillary action. The capillary wick must be suitable so that the required amount of liquid can be absorbed.

The wick may comprise a porous interface different from a capillary material for absorbing and conveying the desired amount of liquid aerosol-forming substrate.

The liquid aerosol-forming substrate may be adsorbed, coated, impregnated of otherwise loaded onto any suitable carrier or support.

The wick may comprise a porous ceramic. The wick may comprise a solid-open-cell porous ceramic. The porous ceramic allows the liquid aerosol-forming substrate to flow into the wick.

The vaporiser may comprise at least one heating element. The at least one heating element may heat the liquid aerosol-forming substrate by one or more of conduction, convection and radiation.

The at least one heating element may be powered by a non-electric power supply, such as a combustible fuel. The at least one heating element may comprise a thermally conductive element, also known as thermo-conductive element, that is heated by combustion of a gas fuel. The at least one heating element may heat the aerosol-forming substrate by means of conduction and may be at least partially in thermal contact with the wick in which the substrate is absorbed.

As used herein, “thermo-conductive” and "thermally conductive" refers to a material having a thermal conductivity of at least 10 W/m.k, preferably at least 40 W/m.k, more preferably at least 100 W/m.k, at 23 degrees Celsius and a relative humidity of 50%. Preferably, the thermally conductive material has a thermal conductivity of at least 40 W/m.k, preferably at least 100 W/m.k, more preferably at least 150 W/m.k, even more preferably at least 200 W/m.k, at 23 degrees Celsius and a relative humidity of 50%.

The heat from the at least one heating element may be conducted to the wick and the wick may heat the liquid aerosol-forming substrate. The heat from the at least one heating element may be conducted to the wick by means of an intermediate heat conductive element. The heat from the at least one heating element may be directly conducted to the wick without any intermediate heat conductive element.

The replaceable cartridge may be electrically operated and the vaporizer may comprise an electric heating element for heating the aerosol-forming substrate. The electric heating element may be powered by an electric power supply.

The electric heating element may comprise a single heating element. The electric heating element may comprise more than one heating element for example two, or three, or four, or five, or six or more heating elements. The heating element or heating elements may be arranged appropriately so as to most effectively heat the liquid aerosol-forming substrate.

When the at least one heating element comprises an electric heating element, the electric heating element may comprise an electrically resistive material. Suitable electrically resistive materials include but are not limited to: semiconductors such as doped ceramics, electrically “conductive” ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys and composite materials made of a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Suitable doped ceramics may include doped silicon carbides. Suitable metals may include titanium, zirconium, tantalum and metals from the platinum group. Suitable metal alloys may include stainless steel, Constantan, nickel-, cobalt-, chromium-, aluminium- titaniumzirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese- and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, Timetai®, iron-aluminium based alloys and iron-manganese-aluminium based alloys. Timetai® is a registered trade mark of Titanium Metals Corporation, 1999 Broadway Suite 4300, Denver Colorado. In composite materials, the electrically resistive material may optionally be embedded in, encapsulated or coated with an insulating material or vice-versa, depending on the kinetics of energy transfer and the external physicochemical properties required. The heating element may comprise a metallic etched foil insulated between two layers of an inert material. In that case, the inert material may comprise Kapton®, all-polyimide or mica foil. Kapton® is a registered trade mark of E.l. du Pont de Nemours and Company, 1007 Market Street, Wilmington, Delaware 19898, United States of America.

When the at least one heating element comprises an electric heating element, the electric heating element may comprise an infra-red heating element, a photonic source or an inductive heating element.

The electric heating element may be a disk heating element. The electric heating element may comprise a flexible sheet of material. The electric heating element may include a heating wire or filament, for example a nickel-chromium (Ni-Cr), platinum, tungsten or alloy wire, or a heating plate. The electric heating element may be deposited in or on a rigid carrier material.

The electric heating element may comprise a heat sink, or heat reservoir, comprising a material capable of absorbing and storing heat and subsequently releasing the heat over time to heat the liquid aerosol-forming substrate. The heat sink may be formed of any suitable material, such as a suitable metal or ceramic material. The material may have a high heat capacity (sensible heat storage material), or may be a material capable of absorbing and subsequently releasing heat via a reversible process, such as a high temperature phase change. Suitable sensible heat storage materials include but are not limited to: silica gel, alumina, carbon, glass mat, glass fibre, ceramics minerals, a metal or alloy such as aluminium, silver or lead and a cellulose material. Other suitable materials which release heat via a reversible phase change include but are not limited to: paraffin, sodium acetate, naphthalene, wax, polyethylene oxide, a metal, metal salt, a mixture of eutectic salts or an alloy.

The heat sink may be arranged such that it is directly in contact with the liquid aerosolforming substrate and can transfer the stored heat directly to the substrate. The heat stored in the heat sink or heat reservoir may also be transferred to the liquid aerosol-forming substrate by means of a heat conductor, such as a metallic tube.

The wick may comprise a thermo-conductive material. This may allow the wick to receive heat so as to vaporise the liquid aerosol-forming substrate absorbed by the wick. The heat may be received from a heating element in thermal contact with the wick.

The wick may be a heating element. When the wick is a heating element, it may be the sole heating element of the vaporiser. Likewise, when the wick is a heating element, the vaporiser may comprise one or more heating elements in addition to the wick. When the wick is a heating element, the wick may comprise an electrically conductive material that may be heated when supplied with an electric current from a power supply. The electrically conductive material may be a porous ceramic.

As used herein, “electrically conductive” refers to materials having an electrical resistivity of less than or equal to 1 x10-4 ohm metres (Q.m), at 20 degrees Celsius.

The wick may be arranged to function as a heat sink.

In use, the liquid aerosol-forming substrate may be transferred from the liquid storage portion into the wick and vaporized by the vaporiser to form a supersaturated vapour. The supersaturated vapour is mixed with air entering the replaceable cartridge through the cartridge air inlet and carried within the air flow route. During the flow, the vapour condenses to form the aerosol and the aerosol is carried towards the mouth of a user through the cartridge air outlet.

The replaceable cartridge may comprise a thermo-chromatic and thermo-conductive element in thermal contact with the vaporiser, the thermo-chromatic and thermo-conductive element having a temperature threshold beyond which the thermo-chromatic and thermo- conductive element performs a chromatic change.

The thermo-chromatic and thermo-conductive element may be in thermal contact with the wick. The thermo-chromatic and thermo-conductive element may be in thermal contact with the at least one heating element.

Since the thermo-chromatic and thermo-conductive element has a temperature threshold beyond which it performs a chromatic change and is in thermal contact with the vaporiser, the temperature threshold may be selected to correspond to a temperature beyond which the vaporiser overheats, for example due to an insufficient amount of liquid aerosolforming substrate in the liquid storage portion. Therefore, the chromatic change may be an indication of the vaporiser being overheated. As a result, the thermo-chromatic and thermo- conductive element may provide a reliable and inexpensive solution for preventing overheating of the vaporiser and insufficient amounts of liquid aerosol-forming substrate in the liquid storage portion. Since overheating of the vaporiser and an insufficient amount of liquid aerosol-forming substrate may give rise to undesirable compounds, smells, flavours or a combination of them in the generated aerosol, and it may also give rise to an aerosol with an undesired particle size, the provision of the thermo-chromatic and thermo-conductive element may be beneficial to improve a user’s experience.

The chromatic change may be irreversible. This is beneficial to ensure that the indication of the vaporiser being overheated is not reversed by refilling the replaceable cartridge, thus reducing the risk of using non-compliant aerosol-forming substrates in the cartridge.

The liquid storage portion may be annular and may define an inner passageway surrounded by the liquid storage portion.

An annular liquid storage portion that defines an inner passageway may allow for a more compact replaceable cartridge, as the inner passageway is intended for the flow of vaporised liquid aerosol-forming substrate whilst the surrounding liquid storage portion comprises the liquid aerosol-forming substrate prior to vaporisation.

The cartridge air outlet may be disposed at a downstream end of the inner passageway.

The replaceable cartridge may comprise a mouthpiece. The mouthpiece may comprise the cartridge air outlet. The replaceable cartridge may comprise any suitable number of cartridge air outlets. The replaceable cartridge may comprise a plurality of cartridge air outlets.

The replaceable cartridge may comprise any suitable number of cartridge air inlets. The replaceable cartridge may comprise a plurality of cartridge air inlets.

The vaporiser may be disposed at an upstream end of the inner passageway. This arrangement is beneficial to facilitate the absorption of liquid aerosol-forming substrate in the wick and the entrainment of vaporised liquid aerosol-forming substrate into the air flow along the inner passageway.

As used herein, the terms “upstream”, “front”, “downstream” and “rear” are used to describe the relative positions of components or portions of components of the replaceable cartridge and the aerosol-generating system in relation to the direction in which a user draws on the replaceable cartridge or the aerosol-generating system during use. Likewise, these terms are also used to describe the relative positions of components or portions of components of the aerosol-generating device in relation to the direction of the aerosolgenerating device when assembled in the aerosol-generating system.

The replaceable cartridge and the aerosol-generating system comprise a downstream end through which, in use, an aerosol exits the cartridge and the system for delivery to a user. The aerosol-generating device comprises a downstream end, which is the end configured to be the closest to the downstream end of the aerosol-generating system when the aerosolgenerating device is assembled in the aerosol-generating system. The proximal end of the replaceable cartridge, the aerosol-generating system and the aerosol-generating device may also be referred to as the mouth end. In use, a user draws on the mouth end of the replaceable cartridge and the aerosol-generating system. The mouth end is downstream of the distal end and is opposite the distal end. The distal end is also known as upstream end. Components, or portions of components, of the replaceable cartridge, the aerosol-generating system and the aerosol-generating device may be described as being upstream or downstream of one another based on their relative positions between the proximal end and the distal end of the cartridge, the aerosol-generating system and the aerosol-generating device. The distal end of a component, or portion of a component, of the cartridge, the aerosol-generating system and the aerosol-generating device is the portion at the end closest to the upstream end of the cartridge, the aerosol-generating system and the aerosol-generating device. The proximal end of a component, or portion of a component, of the cartridge, the aerosol-generating system and the aerosol-generating device is the portion at the end closest to the downstream end of the cartridge, the aerosol-generating system and the aerosol-generating device.

As used herein, the term “longitudinal” refers to the direction corresponding to the main longitudinal axis of the replaceable cartridge, the aerosol-generating system and the aerosolgenerating device which extends between the upstream and downstream ends of the replaceable cartridge, the aerosol-generating system and the aerosol-generating device.

During use, air is drawn through replaceable cartridge, the aerosol-generating system and the aerosol-generating device in the longitudinal direction. The term “transverse” refers to the direction that is perpendicular to the longitudinal axis. Any reference to the “cross-section” of the replaceable cartridge, the aerosol-generating system and the aerosol-generating device or a component of the replaceable cartridge, the aerosol-generating system and the aerosolgenerating device refers to the transverse cross-section unless stated otherwise.

The term “length” denotes the dimension of a component of the replaceable cartridge, the aerosol-generating system and the aerosol-generating device in the longitudinal direction.

The replaceable cartridge may have a length of between about 1.5 cm and 2.75 cm. The replaceable cartridge may have a diameter of between about 0.3 cm and 0.7 cm.

The thermo-chromatic and thermo-conductive element is a separate element to the liquid aerosol-forming substrate and is not suspended or dissolved in the liquid aerosolforming substrate. The thermo-chromatic and thermo-conductive element may comprise a main body. The main body may comprise a porous ceramic. The thermo-chromatic and thermo-conductive element may comprise a layer of thermo-chromatic material on the main body. The thermo-chromatic and thermo-conductive element may comprise a layer of thermo- chromatic material printed on the main body. The layer of thermo-chromatic material may comprise inorganic materials or Leuco dyes. The layer of thermo-chromatic material may comprise Chromium (III) oxide.

The thermo-chromatic and thermo-conductive element may comprise a porous layer. The porous layer may comprise a temperature-sensitive material, such as a PTC thermistor or an NTC thermistor.

PTC thermistors and NTC thermistors are thermally sensitive resistors which may be heated when an electric current is supplied to them. When the PTC thermistor or NTC thermistor is heated, the temperature and the resistance of the PTC thermistor or NTC thermistor may vary according to a function which relates both parameters.

In a PTC thermistor, there is a stabilised temperature range in which the resistance of the PTC thermistor increases when the temperature of the PTC thermistor increases within the stabilised temperature range. Likewise, in an NTC thermistor, there is a stabilised temperature range in which the resistance of the NTC thermistor decreases when the temperature of the at least one PTC thermistor increases within the stabilised temperature range.

Within the stabilised temperature range, the increase or decrease in the resistance of the PTC thermistor or NTC thermistor when its temperature increases is normally sharp enough to allow for a very slow variation in the temperature of the PTC thermistor or NTC thermistor. As used herein, “stabilised temperature range” should be construed as a range of temperatures of a PTC thermistor or NTC thermistor in which the temperature is not necessarily constant, even if the variation in the temperature of the PTC thermistor or NTC thermistor may be negligible with respect to the variation in the resistance of the PTC thermistor or NTC thermistor.

Therefore, the at least one PTC thermistor may stabilise at substantially the reference temperature (or at a temperature slightly above or below the reference temperature) within the stabilised temperature range for periods of time that may be longer than the normal operating time of the replaceable cartridge of the present disclosure.

The thermo-chromatic and thermo-conductive element comprising a porous layer having a temperature-sensitive material (such as a PTC thermistor or an NTC thermistor) may be less prone to overheating, since the temperature of the temperature-sensitive material may not significantly exceed the reference temperature. The reference temperature of the thermo- chromatic and thermo-conductive element may be chosen to be similar to, and preferably slightly greater than, the temperature threshold of the thermo-chromatic and thermo- conductive element. This may avoid overheating of the thermo-chromatic and thermo- conductive element when the vaporiser is overheated. The wick may have a peripheral wall extending along the longitudinal direction of the replaceable cartridge. The thermo-chromatic and thermo-conductive element may be disposed at least partially around the peripheral wall of the wick.

By disposing the thermo-chromatic and thermo-conductive element at least partially around the peripheral wall of the wick, the thermal contact between the thermo-chromatic and thermo-conductive element and the wick may be facilitated.

The thermo-chromatic and thermo-conductive element may comprise an absorbing material. This may allow the liquid aerosol-forming substrate to flow from the liquid storage portion to the wick through the thermo-chromatic and thermo-conductive even if the thermo- chromatic and thermo-conductive element is disposed at least partially around the peripheral wall of the wick.

The replaceable cartridge may comprise a housing. The housing may comprise a transparent portion, the transparent portion allowing the thermo-chromatic and thermo- conductive element to be seen from the exterior of the replaceable cartridge.

The transparent portion may allow a user to perceive the chromatic change of the thermo-chromatic and thermo-conductive and thus interpret that the vaporiser is overheated.

The transparent portion may correspond to a section of the housing. The transparent portion may correspond to the entire housing.

An aerosol-generating system may be provided. The aerosol-generating system may comprise any of the above replaceable cartridges and a reusable aerosol-generating device. The reusable aerosol-generating device may comprise a power supply configured to provide power to the vaporiser.

As used herein, the term “aerosol-generating device” refers to a device comprising a power supply configured to interact with an aerosol-forming substrate of a cartridge to generate an aerosol. A “reusable aerosol-generating device” denotes an aerosol-generating device that is configured to form an aerosol-generating system with a replaceable cartridge, such that the reusable aerosol-generating device can be combined with a new replaceable cartridge when a replaceable cartridge is used up and disposed of.

As used herein, the term “aerosol-generating system” refers to the combination of an aerosol-generating device and the cartridge comprising the aerosol-forming substrate.

Since the aerosol-generating system comprises the replaceable cartridges described above, the advantages specified above for the replaceable cartridges also apply to the system itself.

The aerosol-generating device may comprise a control unit.

The control unit may be any suitable control unit. The control unit may comprise any suitable electric circuitry and electrical components. The control unit may comprise a processor and a memory. The control unit may be configured to control the supply of power, such as an electric current, from the power supply to the vaporiser of the replaceable cartridge.

The control unit may comprise electric circuitry connected to the power supply and the vaporiser. The electric circuitry may comprise a microprocessor. The microprocessor may be a programmable microprocessor, a microcontrol unit, an application specific integrated chip (ASIC) or other electronic circuitry capable of providing control. The electric circuitry may comprise further electronic components. The control unit may be configured to supply power continuously to the vaporiser following activation of the aerosol-generating device. The control unit may be configured to supply power intermittently to the vaporiser. The control unit may be configured to supply power to the vaporiser on a puff-by-puff basis.

The control unit may be configured to determine or estimate the temperature of the vaporiser, the thermo-chromatic and thermo-conductive element or both the vaporiser and the thermo-chromatic and thermo-conductive element and to stop the supply of power from the power supply to the vaporiser when the determined or estimated temperature exceeds a predetermined threshold stored in the control unit.

The determination or estimation of the temperature of the vaporiser, the thermo- chromatic and thermo-conductive element or both the vaporiser and the thermo-chromatic and thermo-conductive element and stopping the supply of power when a determined or estimated temperature exceeds a pre-determined threshold stored in the control unit may be beneficial to ensure that the aerosol-generating system is not operative when the vaporiser is overheated. This may reduce the risk of using the aerosol-generating system when the vaporiser is overheated, for example due to an insufficient supply of liquid-aerosol-forming substrate to the wick. This may diminish the risk of inhaling undesirable compounds, aerosols with undesired smell, flavour or particle size, or a combination of them, thus improving a user’s experience.

The temperature of the vaporiser, the thermo-chromatic and thermo-conductive element or both the vaporiser and the thermo-chromatic and thermo-conductive element may be determined or estimated as a function of the conductivity of a component of the vaporiser, the thermo-chromatic and thermo-conductive element or both the vaporiser and the thermo- chromatic and thermo-conductive element, relying on the known relationship between conductivity and temperature of a certain material. This may provide for a precise and inexpensive manner of determining or estimating the temperature of the vaporiser, the thermo- chromatic and thermo-conductive element or both the vaporiser and the thermo-chromatic and thermo-conductive element.

The component of the thermo-chromatic and thermo-conductive element on which conductivity is measured may be the porous layer. The component of the vaporiser on which conductivity is measured may be the heating element. The component of the vaporiser, the thermo-chromatic and thermo-conductive element or both the vaporiser and the thermo-chromatic and thermo-conductive element on which conductivity is measured may form a feedback loop with the control unit. This may facilitate the measurement of the conductivity of the component and, as a result, the determination or estimation of the temperature of the component.

The aerosol-generating device may comprise a display or audible alarm. The control unit being may be configured to change a warning signal emitted by the display or audible alarm when the determined or estimated temperature exceeds the pre-determined threshold stored in the control unit.

The change in the warning signal may be advantageous to provide a user with an indication that the replaceable cartridge needs to be replaced. The warning signal may be used in addition to the provision of the thermo-chromatic and thermo-conductive element, thus providing a double indication about the suitability of the replaceable cartridge.

The pre-determined temperature threshold stored in the control unit maybe substantially the same as the temperature threshold of the thermo-chromatic and thermo- conductive element. This may provide for a coherent double indication about the suitability of the replaceable cartridge.

The temperature threshold of the thermo-chromatic and thermo-conductive element may be between about 240 degrees Celsius and 250 degrees Celsius, preferably 245 degrees Celsius.

The pre-determined temperature threshold stored in the control unit may be between about 240 degrees Celsius and 250 degrees Celsius, preferably 245 degrees Celsius.

The electric circuitry may be operable to disable the replaceable cartridge in a permanent manner when the determined or estimated temperature exceeds the predetermined threshold stored in the control unit.

Permanently disabling the replaceable cartridge may provide for a greater user safety. There may be a danger that cartridges could be refilled with inferior and possibly non- compliant substances - by disabling the replaceable cartridge in a permanent manner, the cartridge cannot be refilled and reused.

The power supply may be any suitable type of power supply. The power supply may be a DC power supply. The power supply may be a battery, such as a rechargeable lithium ion battery. The power supply may be another form of charge storage device, such as a capacitor. The power supply may require recharging. The power supply may have a capacity that allows for the storage of enough energy for one or more uses of the device. For example, the power supply may have sufficient capacity to allow for the continuous generation of aerosol for a period of around six minutes, corresponding to the typical time taken to smoke a conventional cigarette, or for a period that is a multiple of six minutes. In another example, the power supply may have sufficient capacity to allow for a predetermined number of uses of the device or discrete activations. The power supply may be a DC power supply having a DC supply voltage in the range of about 2.5 Volts to about 4.5 Volts and a DC supply current in the range of about 1 Amp to about 10 Amps (corresponding to a DC power supply in the range of about 2.5 Watts to about 45 Watts).

The aerosol-generating device may advantageously comprise a DC/AC inverter, which may comprise a Class-C, Class-D or Class-E power amplifier.

The aerosol-generating device may further comprise a DC/DC converter between the power supply and the DC/AC inverter.

The aerosol-generating device may comprise a device housing. The device housing may be elongate. As used herein, the term “elongate” means that an element has a length dimension that is greater than its width dimension or its diameter dimension, for example twice or more its width dimension or its diameter dimension.

The device housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics or composite materials containing one or more of those materials, or thermoplastics that are suitable for food or pharmaceutical applications, for example polypropylene, polyetheretherketone (PEEK) and polyethylene. The material may be light and non-brittle.

The device housing may comprise a device air inlet. The device air inlet may be configured to enable ambient air to enter the device housing. The device may comprise any suitable number of device air inlets. The device may comprise a plurality of device air inlets.

The device housing may comprise a device air outlet. The device air outlet may be configured to enable air to exit the device housing for delivery to the air inlet of the replaceable cartridge. The device may comprise any suitable number of device air outlets. The device may comprise a plurality of device air outlets.

The device air inlet may constitute the air inlet of the aerosol-generating system. The cartridge air outlet may constitute the air outlet of the aerosol-generating system.

The aerosol-generating device may comprise an airflow sensor to detect airflow indicative of a user taking a puff. The airflow sensor may be an electro-mechanical device. The airflow sensor may be any of: a mechanical device, an optical device, an opto-mechanical device and a micro electro-mechanical systems (MEMS) based sensor. The aerosolgenerating device may comprise a manually operable switch for a user to initiate a puff.

The aerosol-generating device may comprise an indicator for indicating when the at least one heating element is activated. The indicator may comprise a light, activated when the at least one heating element is activated.

The aerosol-generating device may comprise at least one electrical connector. The at least one electrical connector may be configured to charge the power supply. The at least one electrical connector may be configured to be connected to another electrical device. The at least one electrical connector may comprise an external plug or socket comprising at least one external electrical contact allowing the aerosol-generating device to be connected to another electrical device. For example, the aerosol-generating device may comprise a USB plug or a USB socket to allow connection of the aerosol-generating device to another USB- enabled device. For example, the USB plug or USB socket may allow the connection of the aerosol-generating device to a USB charging device to charge a rechargeable power supply within the aerosol-generating device. The USB plug or USB socket may support the transfer of data to or from, or both to and from, the aerosol-generating device. Likewise, the aerosolgenerating device may be connected to a computer to transfer data to the device, such as new heating profiles.

When the aerosol-generating device comprises a USB plug or USB socket, the aerosol-generating device may further comprise a removable cover that covers the USB plug or USB socket when not in use. When the USB plug or USB socket is a USB plug, the USB plug may be selectively retractable within the device.

The invention is defined in the claims. However, below there is provided a non- exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment or disclosure described herein.

Ex1. A replaceable cartridge comprising:

- a liquid storage portion comprising a liquid aerosol-forming substrate;

- a vaporiser configured to vaporise the liquid aerosol-forming substrate;

- a cartridge air inlet;

Ex2. The replaceable cartridge of Ex1 , wherein the vaporiser comprises a wick.

Ex3. The replaceable cartridge of Ex2, wherein the wick comprises a capillary material.

Ex4. The replaceable cartridge of any one of Ex2 to Ex3, wherein the wick comprises a porous interface.

Ex5. The replaceable cartridge of any one of Ex2 to Ex4, wherein wick comprises a thermo-conductive material. Ex6. The replaceable cartridge of any one of Ex2 to Ex5, wherein the wick comprises a porous ceramic.

Ex7. The replaceable cartridge of any one of Ex6, wherein the porous ceramic is a solid-open-cell porous ceramic.

Ex8. The replaceable cartridge of any one of Ex1 to Ex7, wherein the liquid storage portion is annular and defines an inner passageway surrounded by the liquid storage portion, wherein the air flow route comprises the inner passageway and wherein the cartridge air outlet is disposed at a downstream end of the inner passageway.

Ex9. The replaceable cartridge of Ex8, wherein vaporiser is disposed at an upstream end of the inner passageway.

Ex10. The replaceable cartridge of any one of Ex1 to Ex9, wherein the vaporiser comprises at least one heating element.

Ex11. The replaceable cartridge of Ex10, wherein the at least one heating element comprises an electric heating element.

Ex12. The replaceable cartridge of Ex11 , wherein the electric heating element is a resistive heating element.

Ex13. The replaceable cartridge of any one of Ex11 to Ex12, wherein the electric heating element is a disk heating element.

Ex14. The replaceable cartridge of any one of Ex11 to Ex13, wherein the electric heating element comprises a heat sink or heat reservoir.

Ex15. The replaceable cartridge of any one of Ex10 to Ex14 when depending on claim 2, wherein the wick is a heating element of the at least one heating element.

Ex16. The replaceable cartridge of any one of Ex1 to Ex15, wherein the thermo- chromatic and thermo-conductive element comprises a main body and preferably wherein the thermo-chromatic and thermo-conductive element comprises a layer of thermo-chromatic material printed on the main body.

Ex17. The replaceable cartridge of Ex16, wherein the main body comprises a porous ceramic.

Ex18. The replaceable cartridge of any one of Ex1 to Ex17, wherein the thermo- chromatic and thermo-conductive element comprises a porous layer.

Ex19. The replaceable cartridge of Ex18, wherein the porous layer comprises a temperature-sensitive material.

Ex20. The replaceable cartridge of Ex19, wherein the temperature-sensitive material is a positive temperature coefficient material or a negative temperature coefficient material.

Ex21. The replaceable cartridge of any one of Ex2 to Ex20 when depending on Ex2, wherein thermo-chromatic and thermo-conductive element is in thermal contact with the wick. Ex22. The replaceable cartridge of any one of Ex10 to Ex21 when depending on Ex10, wherein the thermo-chromatic and thermo-conductive element is in thermal contact with the at least one heating element.

Ex23. The replaceable cartridge of any one of Ex1 to Ex22, wherein the chromatic change is irreversible.

Ex24. The replaceable cartridge of any one of Ex1 to Ex23, wherein the thermo- chromatic and thermo-conductive element comprises an absorbing material.

Ex25. The replaceable cartridge of any one of Ex2 to Ex24 when depending on Ex2, wherein the wick comprises a peripheral wall extending along the longitudinal direction of the replaceable cartridge and wherein the thermo-chromatic and thermo-conductive element is disposed at least partially around the peripheral wall of the wick.

Ex26. The replaceable cartridge of any one of Ex1 to Ex25, further comprising a housing that comprises a transparent portion, the transparent portion allowing the thermo- chromatic and thermo-conductive element to be seen from the exterior of the replaceable cartridge.

Ex27. The replaceable cartridge of any one of Ex1 to Ex26, wherein the liquid aerosolforming substrate comprises nicotine.

Ex28. The replaceable cartridge of Ex27, wherein the liquid aerosol-forming substrate comprises a nicotine salt matrix.

Ex29. The replaceable cartridge of any one of Ex1 to Ex28, wherein the liquid aerosolforming substrate comprises a plant-based material.

Ex30. The replaceable cartridge of any one of Ex29, wherein the plant-based material is a homogenised plant-based material.

Ex31 . The replaceable cartridge of any one of Ex1 to Ex30, wherein the liquid aerosolforming substrate comprises non-tobacco material.

Ex32. The aerosol-generating article of Ex1 to Ex31 , wherein the liquid aerosol-forming substrate comprises tobacco material.

Ex33. The replaceable cartridge of any one of Ex1 to Ex32, wherein the liquid aerosolforming substrate comprises water.

Ex34. The replaceable cartridge of any one of Ex1 to Ex33, wherein the liquid aerosolforming substrate comprises an aerosol-former.

Ex35. The replaceable cartridge of Ex34, wherein the aerosol-former comprises glycerine, propylene glycol or both glycerine and propylene glycol.

Ex36. A reusable aerosol-generating device comprising a power supply configured to provide power to a vaporiser of the replaceable cartridge of any one of Ex1 to Ex35. Ex37. The reusable aerosol-generating device of Ex36, wherein the power supply is configured to be electrically connected to the vaporiser of the replaceable cartridge of any one of Ex1 to Ex35.

Ex38. The reusable aerosol-generating device of any one of Ex36 to Ex37, further comprising a control unit.

Ex39. The reusable aerosol-generating device of any one of Ex36 to Ex38, further comprising a device housing.

Ex40. The reusable aerosol-generating device of any one of Ex36 to Ex39, further comprising a device air inlet and a device air outlet.

Ex41. The reusable aerosol-generating device of Ex40 when depending on Ex39, wherein the device housing comprises the device air inlet and the device air outlet.

Ex42. The reusable aerosol-generating device of any one of Ex36 to Ex41 when depending on Ex38, wherein the control unit is configured to control the supply of power from the power supply to the vaporiser of the replaceable cartridge of any one of Ex1 to Ex35.

Ex43. The reusable aerosol-generating device of any one of Ex36 to Ex42, further comprising a sensor configured detect airflow indicative of a user taking a puff.

Ex44. The reusable aerosol-generating device of any one of Ex36 to Ex43, further comprising at least one electrical connector.

Ex45. The reusable aerosol-generating device of any one of Ex44, wherein the at least one electrical connector comprises an external plug or socket, such as a USB plug or a USB socket.

Ex46. An aerosol-generating system comprising the replaceable cartridge of any one of Ex1 to Ex35 and the reusable aerosol-generating device of any one of Ex36 to Ex45.

Ex47. The aerosol-generating system of Ex46 when depending on Ex38, wherein the control unit is configured to determine or estimate the temperature of the vaporiser and to stop the supply of power from the power supply to the vaporiser when the determined or estimated temperature exceeds a pre-determined threshold stored in the control unit.

Ex48. The aerosol-generating system of Ex47, wherein the temperature of the vaporiser is determined or estimated as a function of the conductivity of a component of the vaporiser.

Ex49. The aerosol-generating system of Ex48 when depending on Ex10, wherein the component of the vaporiser is the at least one heating element.

Ex50. The aerosol-generating system of any one of Ex48 to Ex49, wherein the component of the vaporiser and the control unit form a feedback loop.

Ex51 . The aerosol-generating system of any one of Ex46 to Ex50 when depending on Ex38, wherein the control unit is configured to determine or estimate the temperature of the thermo-chromatic and thermo-conductive element and to stop the supply of power from the power supply to the vaporiser when the determined or estimated temperature exceeds a predetermined threshold stored in the control unit.

Ex52. The aerosol-generating system of Ex51 , wherein the temperature of the thermo- chromatic and thermo-conductive element is determined or estimated as a function of the conductivity of a component of the thermo-chromatic and thermo-conductive element.

Ex53. The aerosol-generating system of Ex52 when depending on Ex18, wherein the component of the thermo-chromatic and thermo-conductive element is the porous layer.

Ex54. The aerosol-generating system of any one of Ex52 to Ex53, wherein the component of the thermo-chromatic and thermo-conductive element and the control unit form a feedback loop.

Ex55. The aerosol-generating system of any one of Ex47 to Ex54, wherein the predetermined threshold stored in the control unit is substantially the same as the temperature threshold of the thermo-chromatic and thermo-conductive element.

Ex56. The aerosol-generating system of any one of Ex47 to Ex55, wherein the aerosolgenerating device comprises a display or audible alarm, the control unit being configured to change a warning signal emitted by the display or audible alarm when the determined or estimated temperature exceeds the pre-determined threshold stored in the control unit.

Ex57. The aerosol-generating system of any one of Ex47 to Ex56, wherein the control unit comprises electric circuitry that may be operable to disable the replaceable cartridge in a permanent manner when the determined or estimated temperature exceeds the predetermined threshold stored in the control unit.

These and other features and advantages of the invention will become more evident in the light of the following detailed description of preferred embodiments, given only by way of illustrative and non-limiting example, in reference to the attached figures:

Figure 1 shows a replaceable cartridge comprising a thermo-chromatic and thermo- conductive element.

Figure 2 illustrates the replaceable cartridge of figure 1 at an instant when the thermo- chromatic and thermo-conductive element has performed a chromatic change.

Figure 3 depicts an aerosol-generating system comprising the replaceable cartridge of figures 1 and 2.

Figure 4 represents the aerosol-generating system of figure 3 at an instant when the thermo-chromatic and thermo-conductive element has performed a chromatic change and a display emits a warning signal. Figure 1 shows a replaceable cartridge 1 comprising a liquid storage portion 2, a vaporiser 10 and a thermo-chromatic and thermo-conductive element 20. The liquid storage portion 2 comprises a liquid aerosol-forming substrate 3.

The vaporiser 10 is configured to vaporise the liquid aerosol-forming substrate 3 and comprises a wick 11 configured to absorb the liquid aerosol-forming substrate 3 and deliver the liquid aerosol-forming substrate 3 to the region of the vaporiser 10 in which it is vaporised. In this embodiment, the vaporiser 10 comprises a disk resistive heating element 12 in thermal contact with the wick 11. The resistive heating element 12 is electrically connected to a first 13 and a second 14 electric pin configured to be supplied with electric current from an electric power supply. The wick 11 comprises a thermo-conductive material, such as a thermo- conductive porous ceramic. Thus, heat generated by the resistive heating element 12 when supplied with electric current is transferred to the wick 11 by thermal conduction and the liquid aerosol-forming substrate 3 absorbed by the wick 11 is vaporised.

The thermo-chromatic and thermo-conductive element 20 is in thermal contact with the vaporiser 10. In particular, in the embodiment of figure 1 , the wick 11 comprises a peripheral wall 15 extending along the longitudinal direction of the replaceable cartridge 1 and the thermo-chromatic and thermo-conductive element 20 is disposed partially around the peripheral wall 15 of the wick 11 , in thermal contact with the wick 11.

In the embodiment of figure 1 , the liquid storage portion 2 is annular and defines an inner passageway 7 surrounded by the liquid storage portion 2. A cartridge air outlet 4 is disposed at a downstream end of the inner passageway 7 and the vaporiser 10 is disposed at an upstream end of the inner passageway 7.

The replaceable cartridge 1 has a cartridge air inlet 5, the cartridge air inlet 5 and the cartridge air outlet 4 being arranged to define an air flow route between the cartridge air inlet 5 and the cartridge air outlet 4. The air flow route goes through the wick 11 , such that the liquid aerosol-forming substrate 3 vaporised at the wick 11 is entrained with air entering the replaceable cartridge 1 through the cartridge air inlet 5 and flows along the inner passageway 7 towards the cartridge air outlet 4. The cartridge air outlet 4 allows the exit of vaporised liquid aerosol-forming substrate 3.

The thermo-chromatic and thermo-conductive element 20 comprises a main body 21 , comprising a porous ceramic, and a layer of thermo-chromatic material 22 printed on the main body. The thermo-chromatic and thermo-conductive element 20 also comprises a porous layer (not represented) comprising a temperature-sensitive material.

Figure 2 illustrates the replaceable cartridge 1 of figure 1 at an instant when the liquid storage portion 2 comprises a reduced amount of liquid aerosol-forming substrate 3. In such case, when the replaceable cartridge 1 is in use, an insufficient amount of liquid aerosolforming substrate 3 is absorbed by and heated in the wick 11 , which causes the vaporiser 10 to overheat. Since the thermo-chromatic and thermo-conductive element 20 is in thermal contact with the wick 11 and the resistive heating element 12, the temperature of the thermo- chromatic and thermo-conductive element 20 rises. The thermo-chromatic and thermo- conductive element 20 has a temperature threshold beyond which the thermo-chromatic and thermo-conductive element 20 performs a chromatic change. The chromatic properties of the thermo-chromatic and thermo-conductive element 20 are chosen such that the thermo- chromatic and thermo-conductive element 20 performs a chromatic change when the temperature of the thermo-chromatic and thermo-conductive element 20 corresponds to a temperature of the vaporiser 10 (such as a temperature of the wick 11 or the resistive heating element 12) at which the vaporiser 10 overheats.

Therefore, at the instant of figure 2, in which the insufficient amount of liquid aerosolforming substrate 3 leads to the overheating of the wick 11 and the resistive heating element 12, the thermo-chromatic and thermo-conductive element 20 has performed a chromatic change, which in figure 2 is represented with dots. The chromatic change is interpreted by a user as an indication of the replaceable cartridge 1 being no longer suitable for providing a satisfactory user’s experience. The user can thus proceed to dispose of the replaceable cartridge 1 and replace it with a new cartridge in an aerosol-generating system.

In the embodiment of figure 2, the replaceable cartridge 1 comprises a housing 6 that comprises a transparent portion, the transparent portion allowing the thermo-chromatic and thermo-conductive element 20 to be seen from the exterior of the replaceable cartridge 1. In figure 2, the transparent portion is an outer peripheral wall of the housing 6.

Figure 3 illustrates an aerosol-generating system 200 comprising the replaceable cartridge 1 of figures 1 and 2 and a reusable aerosol-generating device 100. The reusable aerosol-generating device 100 comprises a power supply 101 configured to provide an electric current to the resistive heating element 12 via the first 13 and second 14 electric pins.

The aerosol-generating device 100 comprises a control unit 102 configured to control the supply of electric current from the power supply 101 to the resistive heating element 12.

The power supply 101 and the control unit 102 are all housed within a device housing 107. The control unit 102 is arranged at the proximal end of the device 100. An electrical connector 103 is arranged at a distal end of the device housing 107.

The control unit 102 comprises a DC/AC inverter, including a Class-D power amplifier. The control unit 102 is also configured to control recharging of the power supply 101 from the electrical connector 103. The control unit 102 further comprises a sensor (not shown) configured to sense when a user is drawing on the aerosol-generating system 200.

The control unit 102 is configured to determine or estimate the temperature of the vaporiser 10, the thermo-chromatic and thermo-conductive element 20 or both the vaporiser 10 and the thermo-chromatic and thermo-conductive element 20, and to stop the supply of electric current from the power supply 101 to the vaporiser 10 when the determined or estimated temperature exceeds a pre-determined threshold stored in the control unit 102.

The aerosol-generating device 100 comprises a display 104. The control unit 102 is configured to change a warning signal emitted by the display 104 when the determined or estimated temperature exceeds the pre-determined threshold stored in the control unit 102.

Figure 4 shows the aerosol-generating system of figure 3 at an instant when there is an insufficient amount of liquid aerosol-forming substrate 3 in the liquid storage portion 2. This leads to an overheating of the vaporiser 10. As explained above, the thermo-conductive element 20 performs a chromatic change and the display 104 emits a warning signal, represented with flashing lines in figure 4. Therefore, two independent systems for indicating overheating of the vaporiser 10 are provided in the aerosol-generating system 200. This improves the robustness of the protection against overheating.

Advantageously, the pre-determined temperature threshold stored in the control unit 102 is substantially the same as the temperature threshold of the thermo-chromatic and thermo-conductive element 20. This may provide for a coherent double indication about the suitability of the replaceable cartridge by means of the chromatic change of the thermo- chromatic and thermo-conductive element 20 and the warning signal emitted by the display 104.

Furthermore, since the control unit 102 stops the supply of electric current from the power supply 101 to the vaporiser 10, the risk of using the aerosol-generating system 200 when the vaporiser 10 is overheated is further reduced, even if a user overlooks or ignores the chromatic change of the thermo-chromatic and thermo-conductive element 20 and the warning signal of the display 104.

Claims

1 . A replaceable cartridge comprising:

- a liquid storage portion comprising a liquid aerosol-forming substrate;

- a vaporiser configured to vaporise the liquid aerosol-forming substrate, the vaporiser comprising a wick configured to absorb the liquid aerosol-forming substrate;

- a cartridge air inlet;

2. The replaceable cartridge of claim 1 , wherein the liquid storage portion is annular and defines an inner passageway surrounded by the liquid storage portion, wherein the air flow route comprises the inner passageway and wherein the cartridge air outlet is disposed at a downstream end of the inner passageway.

3. The replaceable cartridge of claim 2, wherein vaporiser is disposed at an upstream end of the inner passageway.

4. The replaceable cartridge of any one of the preceding claims, wherein the thermo- chromatic and thermo-conductive element comprises a main body.

5. The replaceable cartridge of claim 4, wherein the thermo-chromatic and thermo- conductive element comprises a layer of thermo-chromatic material printed on the main body.

6. The replaceable cartridge of claim 4 or 5, wherein the main body comprises a porous ceramic.

7. The replaceable cartridge of any one of the preceding claims, wherein the thermo- chromatic and thermo-conductive element comprises a porous layer, the porous layer comprising a temperature-sensitive material.

8. The replaceable cartridge of any one of the preceding claims, wherein wick comprises a thermo-conductive material.

9. The replaceable cartridge of any one of the preceding claims, wherein the thermo- chromatic and thermo-conductive element comprises an absorbing material.

10. The replaceable cartridge of any one of the preceding claims, wherein the wick comprises a peripheral wall extending along the longitudinal direction of the replaceable cartridge and wherein the thermo-chromatic and thermo-conductive element is disposed at least partially around the peripheral wall of the wick.

11 . The replaceable cartridge of any one of the preceding claims, wherein the chromatic change is irreversible.

12. An aerosol-generating system comprising:

- the replaceable cartridge of any one of the preceding claims,

- a reusable aerosol-generating device comprising a power supply configured to provide power to the vaporiser.

13. The aerosol-generating system of claim 12, wherein the aerosol-generating device comprises a control unit configured to control the supply of power from the power supply to the vaporiser.

14. The aerosol-generating system of claim 13, wherein the control unit is configured to determine or estimate the temperature of the vaporiser, the thermo-chromatic and thermo- conductive element or both the vaporiser and the thermo-chromatic and thermo-conductive element and to stop the supply of power from the power supply to the vaporiser when the determined or estimated temperature exceeds a pre-determined threshold stored in the control unit.

15. The aerosol-generating system of claim 14, wherein the aerosol-generating device comprises a display or audible alarm, the control unit being configured to change a warning signal emitted by the display or audible alarm when the determined or estimated temperature exceeds the pre-determined threshold stored in the control unit.