Aerosol-generating article comprising a frame

Abstract

An aerosol-generating article (110) for use with an aerosol-generating device to generate an aerosol. The aerosol-generating article (110) comprises a first cavity (33) and a second cavity (34), in which the second cavity (34) is located in series with the first cavity (33). The aerosol-generating article (110) comprises a first aerosol-generating substrate (45) positioned in the first cavity (33) and a second aerosol-generating substrate (46), different to the first aerosol-forming substrate and positioned in the second cavity (34). The aerosol-generating article (110) comprises an air inlet, an air outlet (12), and an airflow passage extending between the air inlet and the air outlet through the first cavity (33) and the second cavity (34). The aerosol-generating article (110) comprises a first planar external surface (21) and a second planar external surface (22). The aerosol-generating article (110) comprises a frame (50) positioned between the first planar external surface (21) and the second planar external surface (22), wherein the frame (50) at least partially defines the first cavity (33) and the second cavity (34).

Description

[0001] AEROSOL-GENERATING ARTICLE COMPRISING A FRAME

[0002] The present disclosure relates to an aerosol-generating article. The present disclosure also relates to an aerosol-generating device for use with the aerosol-generating article. The present disclosure also relates to an aerosol-generating system comprising the aerosol-generating device and the aerosol-generating article.

[0003] A typical aerosol-generating system comprises an aerosol-generating device and an aerosolgenerating article comprising an aerosol-generating substrate. In use, the aerosol-generating device is arranged to heat a heating element that is positioned near, or in contact with, the aerosol-generating substrate which causes the aerosol-generating substrate to heat up and release volatile compounds. These volatile compounds are then entrained in air that is drawn through the aerosol-generating article. As the volatile compounds cool, they condense to form an aerosol that can be inhaled by a consumer.

[0004] A typical aerosol-generating article may appear similar and have similar dimensions to a conventional cigarette. For example, such an aerosol-generating article may be substantially cylindrical and comprise an aerosol-generating substrate in addition to other components such as mouthpiece filter element and a cooling element, which are arranged in the form of a rod and wrapped in a cigarette paper.

[0005] However, a significant portion of the aerosol-generating substrate in these cylindrical aerosolgenerating articles may not be sufficiently heated to form an aerosol during use. This is undesirable since the insufficiently heated portion of the aerosol-generating substrate contributes to the cost of manufacture and transport of the aerosol-generating article but does not contribute to the aerosol delivered to the consumer. Moreover, the components of these cylindrical aerosol-generating articles normally need to have the same or very similar outer diameters so that they can be brought together, accurately positioned in axial alignment and wrapped in a cigarette paper. This can lead to increased cost and complexity of manufacture.

[0006] It is an objective of the present disclosure to provide an aerosol-generating article in which a greater portion of the aerosol-generating substrate is sufficiently heated to form an aerosol during use. It is also an objective of the present disclosure to provide an aerosol-generating article that can be manufactured relatively efficiently and cheaply. It may be desirable to provide an aerosol-generating article that may provide more consistent or controlled delivery of volatile compounds during a puffing session.

[0007] According to the present disclosure, there is provided an aerosol-generating article. The aerosol-generating article is for use with an aerosol-generating device to generate an aerosol. The aerosol-generating article comprises at least one cavity. The aerosol-generating article may comprise a first cavity and a second cavity. The first cavity and the second cavity may be located in series. The aerosol-generating article comprises one or more aerosol-generating substrates. The aerosolgenerating article may comprise a first aerosol-generating substrate. The aerosol-generating article may comprise a second aerosol-generating substrate. The second aerosol-generating substrate may be different to the first aerosol-forming substrate. The first aerosol-generating substrate may be positioned in the first cavity. The second aerosol-generating substrate may be positioned in the second cavity. The aerosol-generating article comprises an air inlet and an air outlet. The aerosol-generating article comprises an airflow passage extending between the air inlet and the air outlet. The airflow passage may extend through the first cavity and the second cavity. The aerosol-generating article comprises a first planar external surface. The aerosol-generating article comprises a second planar external surface. The aerosol-generating article comprises a frame positioned between the first planar external surface and the second planar external surface. The frame may at least partially define the first cavity and the second cavity.

[0008] Advantageously, the frame may allow the aerosol-generating article to be relatively thin whilst maintaining structural rigidity.

[0009] Advantageously, the first planar external surface and the second planar external surface allow for good contact with an external heater, particularly an external heater, of an aerosol-generating device, thereby providing optimum heating of the aerosol-generating substrate.

[0010] Advantageously, aerosol-generating articles of the present disclosure may be heated along substantially their entire length and width, thereby allowing the entire aerosol-generating substrate to be sufficiently heated to generate an aerosol.

[0011] Advantageously, aerosol-generating articles of the present disclosure may be manufactured by layering sheet materials which can be achieved through a continuous manufacturing process, thereby resulting in an aerosol-generating article that is relatively easy and cheap to manufacture.

[0012] Advantageously, the aerosol-generating article of the present disclosure may provide better extraction of aerosol from the aerosol-forming substrate. Therefore, less substrate may be required to generate the required amount of aerosol. Therefore, a cavity in which aerosol-forming substrate is positioned in may be smaller, which may allow multiple cavities, for example the first and second cavity within a defined space of the aerosol-generating article.

[0013] Advantageously, providing the first aerosol-generating substrate and the second aerosolgenerating substrate positioned in the first and second cavities, respectively, may allow the first aerosolgenerating substrate and the second aerosol-generating substrate to be heated separately or together. So aerosol may be generated from one aerosol-generating substrate or two aerosol-generating substrates from a single aerosol-generating article. This may allow a single aerosol-generating article to provide more than one experience. Advantageously, a single aerosol-generating article providing more than one experience may reduce the amount of raw material required to produce two different experiences.

[0014] Advantageously, providing the first aerosol-generating substrate and the second aerosolgenerating substrate positioned in the first and second cavities, respectively, may allow the aerosolgenerating article to provide a longer experience.

[0015] As used herein “in series” refers to the first cavity and second cavity being positioned in series along the airflow passage. That is, in use, air flows sequentially through the first and second cavities (not necessarily in that order) along a single airflow path.

[0016] The frame may be a planar frame.

[0017] The frame may define a frame aperture extending through the thickness of the frame. The frame aperture may define or form the airflow passage of the aerosol-generating article. The frame aperture may define or form the first cavity, the second cavity, or both the first and second cavity of the aerosolgenerating article. For example, the frame may have a hollow cuboid shape or a square hollow tube shape. As a further example, the frame may have a cross-section that is annular in shape, preferably the cross-section in an x / y plane is annular in shape.

[0018] The frame aperture may define or form the first cavity, the second cavity, or both the first and second cavity of the aerosol-generating article.

[0019] The frame may comprise a first frame aperture and a second frame aperture both extending through the thickness of the frame. The first frame aperture and the second frame aperture may least partially define or form the airflow passage of the aerosol-generating article. The first frame aperture may define or form the first cavity. The second frame aperture may define or form the second cavity.

[0020] Preferably, the second cavity is located upstream of the first cavity. Preferably, the aerosolgenerating article may be received by a device such that the second cavity is upstream of the first cavity.

[0021] The airflow passage may comprise a restriction between the first cavity and the second cavity. The restriction may be configured to define a separation between the first cavity and the second cavity while being fluid permeable to allow air and aerosol to flow between the first cavity and the second cavity. Preferably, the restriction is a reduction in the cross-sectional area of the airflow passage.

[0022] Preferably, the frame comprises a dividing wall which separates the first cavity and the second cavity. The dividing wall may extend through the thickness of the frame. Preferably, the dividing wall may be located upstream of the first cavity and downstream of the second cavity. The first cavity and the second cavity may be coaxially aligned with each other. The first cavity and the second cavity may be adjacent to each other and aligned along a longitudinal axis of the aerosol-generating article.

[0023] The dividing wall may define or form an airflow aperture. The airflow aperture may define the restriction of the airflow passage between the air inlet and the air outlet. The airflow aperture may extend between the first cavity and the second cavity. The airflow aperture may extend in a transverse direction to the first aperture and second aperture. The airflow aperture may have any suitable cross-section. Preferably, the airflow aperture has a circular cross-section, an oval cross-section, a square crosssection, or a rectangular cross-section.

[0024] The airflow aperture may have an equivalent diameter greater than or equal to 0.1 millimetres, greater than or equal to 0.4 millimetres, greater than or equal to 0.7 millimetres, or greater than or equal to 1 .0 millimetres.

[0025] The airflow aperture may have an equivalent diameter less than or equal to 3 millimetres, less than or equal to 2.7 millimetres, less than or equal to 2.4 millimetres, less than or equal to 2.1 millimetres. The air inlet may have an equivalent diameter less than or equal to 2.7 millimetres, less than or equal to 1 .8 millimetres, or less than or equal to 1 .5 millimetres.

[0026] The airflow aperture may have an equivalent diameter between 0.1 millimetres and 3 millimetres, between 0.1 millimetres and 2.4 millimetres, between 0.4 millimetres and 2.1 millimetres, between 0.4 millimetres and 1 .8 millimetres, between 0.7 millimetres and 1 .5 millimetres, or between 1 .0 millimetres and 1 .5 millimetres. The airflow aperture may have a width less than a width of the first cavity, the second cavity, or both the first and second cavity. The airflow aperture may have a thickness less than a thickness of the first cavity, the second cavity, or both the first and second cavity.

[0027] The airflow aperture may a width of between 0.3 millimetres and 3 millimetres or between 0.5 millimetres and 2 millimetres. The airflow aperture may have a thickness of between 0.3 millimetres and 3 millimetres or between 0.5 millimetres and 2 millimetres.

[0028] The frame may comprise a frame outer surface. The frame outer surface may extend in a transverse direction, for example between the first planar external surface and the second planar external surface. The frame outer surface may at least partially define or form one or more external surfaces of the aerosol-generating article. For example, the frame outer surface may at least partially define or form one or more external walls of the aerosol-generating article. The frame outer surface may at least partially circumscribe or encircle the frame aperture, for example the first frame aperture and the second frame aperture. The frame outer surface may at least partially circumscribe or encircle the cavity, for example the first cavity and the second cavity.

[0029] The frame may comprise a frame inner surface. The frame inner surface may extend in a transverse direction, for example between the first planar external surface and the second planar external surface. The frame inner surface may define or form a frame aperture outer wall, for example a first frame aperture outer wall and a second frame aperture outer wall. The frame inner surface may define or form a cavity outer wall, for example a first cavity outer wall and a second cavity outer wall. The frame inner surface may at least partially circumscribe or encircle the frame aperture, for example the first frame aperture and the second frame aperture, extending through the thickness of the frame. The frame inner surface may at least partially circumscribe or encircle the cavity, for example the first cavity and the second cavity.

[0030] The frame outer surface may circumscribe or encircle the frame inner surface. The frame inner surface and the frame outer surface may be concentric with one another.

[0031] The aerosol-generating article may comprise one or more external walls extending between the first planar external surface and the second planar external surface. The one or more external walls may collectively define an entire transverse external area of the aerosol-generating article. The frame may at least partially define each of the one or more external walls. The one or more external walls may circumscribe or encircle at least one of the first cavity and the second cavity. The frame may define at least 60 percent, at least 70 percent, at least 80 percent, or at least 90 percent of the entire transverse external area of the aerosol-generating article.

[0032] Preferably, the first cavity has a different length to the second cavity.

[0033] Preferably, the first cavity has a length of at least 5 millimetres, for example a length of at least 6 millimetres, for example a length of at least 7 millimetres. Preferably, the first cavity has a length of at least 9 millimetres, for example a length of at least 10 millimetres, for example a length of at least 1 1 millimetres. Preferably, the first cavity has a length of at least 12 millimetres, for example a length of at least 15 millimetres, for example a length of at least 16 millimetres.

[0034] Preferably, the first cavity has a length of less than 30 millimetres, for example a length of less than 25 millimetres, for example a length less than 22 millimetres, for example a length of less than 20 millimetres. Preferably, the first cavity has a length of less than 18 millimetres, for example a length of less than 16 millimetres, for example a length less than 15 millimetres, for example a length of less than 14 millimetres. Preferably, the first cavity has a length of less than 12 millimetres, for example a length of less than 1 1 millimetres, for example a length less than 10 millimetres.

[0035] The first cavity may have a length between 5 and 20 millimetres. The first cavity may have a length between 6 and 14 millimetres. The first cavity may have a length between 5 and 12 millimetres.

[0036] Preferably, the second cavity has a length of at least 5 millimetres, for example a length of at least 6 millimetres, for example a length of at least 7 millimetres. Preferably, the second cavity has a length of at least 9 millimetres, for example a length of at least 10 millimetres, for example a length of at least 1 1 millimetres. Preferably, the second cavity has a length of at least 12 millimetres, for example a length of at least 15 millimetres, for example a length of at least 16 millimetres.

[0037] Preferably, the second cavity has a length of less than 30 millimetres, for example a length of less than 25 millimetres, for example a length less than 22 millimetres, for example a length of less than 20 millimetres. Preferably, the second cavity has a length of less than 18 millimetres, for example a length of less than 16 millimetres, for example a length less than 15 millimetres, for example a length of less than 14 millimetres. Preferably, the second cavity has a length of less than 12 millimetres, for example a length of less than 1 1 millimetres, for example a length less than 10 millimetres.

[0038] The second cavity may have a length between 5 and 20 millimetres. The second cavity may have a length between 6 and 14 millimetres. The second cavity may have a length between 5 and 12 millimetres.

[0039] The first cavity and the second cavity together may be referred to as a combined cavity. The combined cavity may have a combined cavity length. The combined cavity length is the sum of the length of the first cavity plus the length of the second cavity.

[0040] The combined cavity length may be greater than or equal to 14 millimetres. The combined cavity may have a length equal to a greater than 18 millimetres. The combined cavity may have a length greater than or equal to 22 millimetres. The combined cavity may have a length greater than or equal to 30 millimetres. The combined cavity may have a length greater than or equal to 38 millimetres.

[0041] The combined cavity may have a length less than or equal to 40 millimetres. The combined cavity may have a length less than or equal to 34 millimetres. The combined cavity may have a length less than or equal to 28 millimetres. The combined cavity may have a length less than or equal to 22 millimetres. The combined cavity may have a length less than or equal to 18 millimetres.

[0042] The combined cavity may have a length between 14 millimetres and 40 millimetres. The combined cavity may have a length between 14 millimetres and 34 millimetres. The combined cavity may have a length between 24 millimetres and 28 millimetres.

[0043] Preferably, the first cavity has a different volume to the second cavity.

[0044] Preferably, the volume of the first cavity may be greater than or equal to 30 cubic millimetres, greater than or equal to 100 cubic millimetres, greater than or equal to 200 cubic millimetres, for example greater than 300 cubic millimetres, greater than or equal to 400 cubic millimetres, for example greater than 500 cubic millimetres. Preferably, the volume of the first cavity may be less than or equal to 2000 cubic millimetres, less than or equal to 1500 cubic millimetres, less than or equal to 1000 cubic millimetres, less than or equal to 800 cubic millimetres, less than or equal to 600 cubic millimetres, less than or equal to 500 cubic millimetres, less than or equal to 400 cubic millimetres, less than or equal to 300 cubic millimetres, or less than or equal to 200 cubic millimetres.

[0045] Preferably, the first cavity has a volume between 30 cubic millimetres and 3500 cubic millimetres. The first cavity may have a volume between 30 cubic millimetres and 2500 cubic millimetres. The first cavity may have a volume between 100 cubic millimetres and 1500 cubic millimetres. The first cavity may have a volume between 100 cubic millimetres and 1000 cubic millimetres.

[0046] Preferably, the volume of the second cavity may be greater than or equal to 30 cubic millimetres, greater than or equal to 100 cubic millimetres, greater than or equal to 200 cubic millimetres, for example greater than 300 cubic millimetres, greater than or equal to 400 cubic millimetres, for example greater than 500 cubic millimetres.

[0047] Preferably, the volume of the second cavity may be less than or equal to 2000 cubic millimetres, less than or equal to 1500 cubic millimetres, less than or equal to 1000 cubic millimetres, less than or equal to 800 cubic millimetres, less than or equal to 600 cubic millimetres, less than or equal to 500 cubic millimetres, less than or equal to 400 cubic millimetres, less than or equal to 300 cubic millimetres, or less than or equal to 200 cubic millimetres.

[0048] Preferably, the second cavity has a volume between 30 cubic millimetres and 3500 cubic millimetres. The second cavity may have a volume between 30 cubic millimetres and 2500 cubic millimetres. The second cavity may have a volume between 100 cubic millimetres and 1500 cubic millimetres. The second cavity may have a volume between 100 cubic millimetres and 1000 cubic millimetres.

[0049] The combined cavity may have a combined cavity volume.

[0050] The combined cavity may have a combined cavity volume of greater than or equal to 30 cubic millimetres, greater than or equal to 100 cubic millimetres, greater than or equal to 300 cubic millimetres, greater than or equal to 500 cubic millimetres, greater than or equal to 700 cubic millimetres, greater than or equal to 900 cubic millimetres, greater than or equal to 1000 cubic millimetres, greater than or equal to 2000 cubic millimetres, or greater than or equal to 30 cubic millimetres.

[0051] The combined cavity may have a combined cavity volume of less than or equal to 3500 cubic millimetres, less than or equal to 2500 cubic millimetres, less than or equal to 1500 cubic millimetres, less than or equal to 1000 cubic millimetres, less than or equal to 800 cubic millimetres, less than or equal to 600 cubic millimetres, less than or equal to 500 cubic millimetres, less than or equal to 400 cubic millimetres, or less than or equal to 300 cubic millimetres.

[0052] The combined cavity may have a combined cavity volume between 30 cubic millimetres and 3500 cubic millimetres. The cavity may have a volume between 30 cubic millimetres and 2500 cubic millimetres. The cavity may have a volume between 100 cubic millimetres and 1500 cubic millimetres. The cavity may have a volume between 100 cubic millimetres and 1000 cubic millimetres. Advantageously, the first and second cavities having these dimensions may be large enough to hold sufficient aerosol-generating substrate, while being small enough to allow the aerosol-generating substrate to be positioned relatively close to a heater to allow good heating and being small enough to allow the aerosol-generating article to be small and convenient for a user.

[0053] Preferably, the second cavity is located upstream of the first cavity and the second cavity has a greater volume than the first cavity and alternatively or in addition, the mass of the second aerosolforming substrate is greater than the mass of the first aerosol-forming substrate, and alternatively or in addition the volume of the second aerosol-forming substrate is greater than the volume of the first aerosol-forming substrate.

[0054] Preferably, when the second cavity is located upstream of the first cavity, in which the first cavity comprises a flavourant, for example the first aerosol-generating substrate may comprise a flavourant. Preferably, the second aerosol-forming substrate comprises at least one of nicotine and glycerine.

[0055] The second aerosol-generating substrate may be configured to be heated to a higher temperature than the first aerosol-forming substrate. It may be preferably that the second cavity is located upstream of the first cavity so that the second aerosol-generating substrate may be in closer contact with a heater of an aerosol-generating device.

[0056] The first aerosol-forming substrate may be configured to be heated indirectly by the heater of the aerosol-generating device, by conduction through the aerosol-generating article. The first aerosolforming substrate may be configured to be heated by hot aerosol that is formed from the second aerosolgenerating substrate.

[0057] Advantageously, the second cavity having a greater volume than the first cavity if the second aerosol-generating substrate is required to last for longer the first aerosol-generating substrate during a usage session.

[0058] Advantageously, the first cavity being situated down stream of the second cavity and the first cavity comprising the flavourant may prevent aerosol generated from the first aerosol-generating substrate from having to flow through the second aerosol-generating substrate, which may be detrimental to flavour characteristics of the flavourant.

[0059] Preferably, the second cavity is located upstream of the first cavity, and the first cavity has a greater volume than the second cavity and alternatively, or in addition, the mass of the first aerosolforming substrate is greater than the mass of the second aerosol-forming substrate and alternatively, or in addition the volume of the first aerosol-forming substrate is greater than the volume of the second aerosol-forming substrate.

[0060] Preferably, when the second cavity is located upstream of the first cavity, the first cavity comprises a flavourant, for example the first aerosol-generating substrate may comprise a flavourant. Preferably, the second aerosol-forming substrate comprises at least one of nicotine and glycerine.

[0061] Advantageously, the downstream cavity therefore may comprise a large amount flavourant and this may allow a flavourant having a relatively low density to be used. Advantageously, this may lead to reduced filtration by the first aerosol-forming substrate, leading to less condensation of aerosol as the aerosol forming in the second, upstream, cavity travels through the first cavity and the first aerosol- forming substrate. Advantageously, The flavourant having a greater volume and relatively low density may provide a greater surface area of the flavourant for aerosolization of the flavourant.

[0062] Preferably, when the second cavity is located upstream of the first cavity, the second cavity comprises a flavourant, for example the second aerosol-generating substrate may comprise a flavourant. Preferably, the first aerosol-forming substrate comprises at least one of nicotine and glycerine.

[0063] Advantageously, the second cavity being upstream of the first cavity prevents filtration and condensation of aerosol generated from the first aerosol-generating substrate. This is particularly desirable if the second aerosol-generating substrate is more heat resistant than the first aerosolgenerating substrate and the second aerosol-generating substrate would induce a high level of filtration.

[0064] Preferably, the aerosol former content of the first aerosol-generating substrate is different to the aerosol former content of the second aerosol-generating substrate.

[0065] Preferably, the first aerosol-generating substrate has a lower aerosol former content than the second aerosol-generating substrate. Advantageously, this may allow the first aerosol-generating substrate to heat up faster due to the first aerosol-generating substrate having a lower thermal inertia. This may allow the first aerosol-generating substrate to start generating aerosol within a relatively short time, thus reducing the time taken from initiating heating to aerosol generation.

[0066] The first and second aerosol-generating substrates may comprise the same aerosol former or aerosol formers as each other, or different aerosol formers may be used.

[0067] The first and second aerosol-generating substrates may comprise or consist of the first and second aerosol-generating substrates, respectively. The first and second aerosol-generating substrates may comprise non-aerosol-generating material as well as aerosol-generating material.

[0068] Optionally, the first aerosol-generating substrate may have an aerosol-former content between 10 and 80 percent by weight on a dry weight basis, for example between 20 and 70 percent by weight on a dry weight basis. Optionally, the second aerosol-generating substrate has an aerosol-former content of between 10 and 80 percent by weight on a dry weight basis, for example between 20 and 70 percent by weight on a dry weight basis.

[0069] Preferably, the first aerosol-generating substrate has an aerosol-former content of at least 10 percent, for example at least 15 percent, for example at least 18 percent by weight on a dry weight basis. Preferably, the first aerosol-generating substrate has an aerosol-former content of less than 30 percent, for example less than 25 percent, for example less than 20 percent by weight on a dry weight basis.

[0070] Advantageously, such aerosol former content in the first aerosol-generating substrate may provide a good compromise between allowing the first aerosol-generating substrate to generate aerosol quickly and being able to generate a sufficient quantity of aerosol.

[0071] Preferably, the second aerosol-generating substrate has an aerosol-former content at least 40 percent, 45 percent, or 50 percent by weight on a dry weight basis. Preferably, the second aerosolgenerating substrate has an aerosol-former content of no more than 80 percent, 75 percent or 70 percent by weight on a dry weight basis. Optionally, the aerosol former content of the second aerosol- generating substrate is between 40 and 80 percent, preferably between 45 and 75 percent, more preferably between 50 and 70 percent, by weight on a dry weight basis.

[0072] Since the first aerosol-generating substrate may have a relatively small aerosol former content, it may be depleted relatively quickly. As such, it may be advantageous for the second aerosol-generating substrate to have a relatively high aerosol former content. In this way, the first aerosol-generating substrate may be heated quickly to provide aerosol for earlier puffs during a usage session, and the second aerosol-generating substrate may take longer to heat up but then provide aerosol for later puffs during a usage session, after the first aerosol-generating substrate has been depleted.

[0073] Optionally, the aerosol former content of the second aerosol-generating substrate is at least 1 .1 , 1 .2, 1 .5, 2 or 2.5 times the aerosol former content of the first aerosol-generating substrate by weight on a dry weight basis. Optionally, the aerosol former content of the second aerosol-generating substrate is no more than 10, 8, or 6 times the aerosol former content of the first aerosol-generating substrate.

[0074] The first aerosol-generating substrate may have a different bulk density to the second aerosolgenerating substrate.

[0075] Preferably, the first aerosol-generating substrate has a lower bulk density than the second aerosol-generating substrate. Advantageously, this may allow the first aerosol-generating substrate to heat up faster due to the first aerosol-generating substrate having a lower thermal inertia. This may allow the first aerosol-generating substrate to start generating aerosol within a relatively short time, thus reducing the time taken from initiating heating to aerosol generation.

[0076] Preferably, the first aerosol-generating substrate has a bulk density of between 100 and 600 milligrams per cubic centimetre, for example between 200 and 500 milligrams per cubic centimetre, for example between 300 and 400 milligrams per cubic centimetre. Optionally, the first aerosol-generating substrate has a bulk density of no more than 400, 350 or 300 milligrams per cubic centimetre. Optionally, the first aerosol-generating substrate has a bulk density of between 100 and 400 milligrams per cubic centimetre, preferably between 150 and 350 milligrams per cubic centimetre.

[0077] Advantageously, such a bulk density of the first aerosol-generating substrate may provide a good compromise between allowing the first aerosol-generating substrate to generate aerosol quickly and being able to generate a sufficient quantity of aerosol.

[0078] Preferably, the second aerosol-generating substrate has a bulk density of between 100 and 600 milligrams per cubic centimetre, for example between 200 and 500 milligrams per cubic centimetre, for example between 300 and 400 milligrams per cubic centimetre.

[0079] Optionally, the second aerosol-generating substrate has a bulk density of at least 500, 550 or 600 milligrams per cubic centimetre. Optionally, the second aerosol-generating substrate has a bulk density of no more than 1000, 900 or 800 milligrams per cubic centimetre. Optionally, the second aerosol-generating substrate has a bulk density of between 500 and 1000 milligrams per cubic centimetre, preferably between 550 and 900 milligrams per cubic centimetre.

[0080] Since the first aerosol-generating substrate may have a relatively small bulk density, it may be depleted relatively quickly. As such, it may be advantageous for the second aerosol-generating substrate to have a relatively high bulk density. In this way, the first aerosol-generating substrate may be heated quickly to provide aerosol for earlier puffs during a usage session, and the second aerosol- generating substrate may take longer to heat up but then provide aerosol for later puffs during a usage session, after the first aerosol-generating substrate has been depleted.

[0081] Optionally, the bulk density of the second aerosol-generating substrate is at least 1 .1 , 1 .2, 1 .5, 2 or 2.5 times the bulk density of the first aerosol-generating substrate. Optionally, the bulk density of the second aerosol-generating substrate is at least 20, 50, 100, or 200 milligrams per cubic centimetre greater than the bulk density of the first aerosol-generating substrate.

[0082] Optionally, the first aerosol-generating substrate has both a lower aerosol former content and a lower bulk density than the second aerosol-generating substrate. Advantageously, the first aerosolgenerating substrate having both a lower aerosol former content and a lower bulk density than the second aerosol-generating substrate may exaggerate the benefits explained above. This may allow the first aerosol-generating substrate to heat up and generate an aerosol quickly, and the second aerosolgenerating substrate to heat up slowly and continue to generate aerosol after the first aerosolgenerating substrate has been depleted.

[0083] Once the aerosol has been generated from the first aerosol-generating substrate, the remaining depleted first aerosol-generating substrate may have a relatively low weight and density. Thus, the second aerosol-generating substrate being located upstream of the first aerosol-generating substrate may be preferable to the other way around as this may advantageously mean that the first aerosol-generating substrate provides a minimal level of filtration of the aerosol generated from the second, upstream aerosol-generating substrate during the later puffs. This may enable a consistent delivery of aerosol to the user during the usage session.

[0084] Preferably, the first aerosol-generating substrate has a different mass to the second aerosolgenerating substrate.

[0085] Optionally, the first aerosol-generating substrate may have a greater than or equal to 50 milligrams, greater than or equal to 80 milligrams, greater than or equal to 1 10 milligrams, greater than or equal to 150 milligrams, greater than or equal to 170 milligrams, greater than or equal to 180 milligrams, greater than or equal to 200 milligrams, greater than or equal to 230 milligrams.

[0086] Optionally, the first aerosol-generating substrate may have a mass less than or equal to 500 milligrams, less than or equal to 400 milligrams, less than or equal to 300 milligrams, less than or equal to 250 milligrams, or less than or equal to 250 milligrams.

[0087] Optionally, the second aerosol-generating substrate may have a mass greater than or equal to 50 milligrams, greater than or equal to 80 milligrams, greater than or equal to 1 10 milligrams, greater than or equal to 150 milligrams, greater than or equal to 170 milligrams, greater than or equal to 180 milligrams, greater than or equal to 200 milligrams, greater than or equal to 230 milligrams.

[0088] Optionally, the second aerosol-generating substrate may have a mass less than or equal to 500 milligrams, less than or equal to 400 milligrams, less than or equal to 300 milligrams, less than or equal to 250 milligrams, or less than or equal to 250 milligrams.

[0089] The first aerosol-generating substrate may have a mass of between 50 milligrams and 500 milligrams, for example between 80 milligrams and 300 milligrams, for example between 1 10 milligrams and 200 milligrams. The second aerosol-generating substrate may have a mass of between 50 milligrams and 500 milligrams, for example between 80 milligrams and 300 milligrams, for example between 1 10 milligrams and 200 milligrams.

[0090] Advantageously, this amount of the first and second aerosol-generating substrates may provide a good compromise between allowing aerosol to be generated quickly and being able to generate a sufficient quantity of aerosol for a usage session.

[0091] The aerosol-generating article may comprising a third cavity. Preferably, a third aerosolgenerating substrate is positioned in the third cavity. The third aerosol-generating substrate may be different to the first aerosol-generating substrate. The third aerosol-generating substrate may be different to the second aerosol-generating substrate. Preferably, the third cavity is located in series with the first cavity and the second cavity. Preferably, the third cavity is located upstream of the second cavity.

[0092] The third cavity may have any of the features as described herein in relation to the first or second cavity.

[0093] The third aerosol-generating substrate may have any of the features as described herein in relation to the first or second aerosol-generating substrate.

[0094] The aerosol-generating article may comprises two or more aerosol-generating substrates.

[0095] The first aerosol-generating substrate and the second aerosol-generating substrate may comprise or be formed of the same type of substrate as each other. Alternatively, the first aerosolgenerating substrate and the second aerosol-generating substrate may comprise or be formed of different types of substrate to each other.

[0096] Preferably, at least one of the first aerosol-generating substrate and the second aerosolgenerating substrate may comprise a flavourant.

[0097] The aerosol-generating article may have a length extending in an x-direction. The aerosolgenerating article may have a width extending in a y-direction. The aerosol-generating article may have a thickness extending in a z-direction.

[0098] The aerosol-generating article may be a substantially flat aerosol-generating article or a substantially planar aerosol-generating article. In particular, a thickness of the aerosol-generating article may less than 50 percent of both a length and a width of the aerosol-generating article. Advantageously, a smaller thickness may provide a small temperature gradient or difference across the thickness of the aerosol-generating substrate during heating.

[0099] The aerosol-generating article may have a quadrilaterally-faced hexahedron shape. The aerosol-generating article may have a rectangular prism shape. The aerosol-generating article may have a cuboid shape. The aerosol-generating article may have a cylindrical shape. The aerosolgenerating article may have a right-angled cylinder shape.

[0100] The aerosol-generating article may have a laminated structure, for example the aerosolgenerating article may comprise or be formed from at least two layers. In particular, the aerosolgenerating article may comprise at least two of: a first external layer, a second external layer, a frame, a first frame layer, a second frame layer, a third frame layer, a first aerosol-generating substrate layer, and a second aerosol-generating substrate layer as discussed in more detail below. Substantially the entirety of the aerosol-generating article, excluding the first and second aerosol-generating substrates and (if present) adhesive, may be paper or cardboard.

[0101] The aerosol-generating article may have a cellulose acetate content of less than 5 percent. The aerosol-generating article may have a cellulose acetate content of less than 3 percent. The aerosolgenerating article may have a cellulose acetate content of less than 1 percent.

[0102] The frame may comprise a peripheral wall. The peripheral wall may circumscribe or encircle at least a portion of the frame first frame aperture and the second frame aperture extending through the thickness of the frame. The peripheral wall may circumscribe or encircle at least a portion of the first cavity and the second cavity. The peripheral wall may circumscribe or encircle the first frame aperture and the second frame aperture extending through the thickness of the frame. The peripheral wall may circumscribe or encircle the first cavity and the second cavity.

[0103] The peripheral wall may be defined or formed by the frame outer surface and the frame inner surface. The peripheral wall may at least partially define or form one or more external surfaces or walls of the aerosol-generating article. The peripheral wall may define or form a frame aperture outer wall. The peripheral wall may define or form a cavity outer wall of at least one of the first cavity and the second cavity.

[0104] The peripheral wall may have a radial thickness. The radial thickness may be defined as the minimum distance between the frame outer surface and the frame inner surface, such as in the x / y plane.

[0105] The peripheral wall may have a radial thickness greater than or equal to 0.5 millimetres. The peripheral wall may have a radial thickness greater than or equal to 1 .5 millimetres. The peripheral wall may have a radial thickness greater than or equal to 2.5 millimetres.

[0106] The peripheral wall may have a radial thickness less than or equal to 3.5 millimetres. The peripheral wall may have a radial thickness less than or equal to 2.5 millimetres.

[0107] The peripheral wall may have a radial thickness between 0.5 millimetres and 3.5 millimetres. The peripheral wall may have a radial thickness between 0.5 millimetres and 2.5 millimetres.

[0108] Advantageously, the peripheral wall having a radial thickness between 0.5 millimetres and 3.5 millimetres has been found to provide good structural strength for the aerosol-generating article whilst not using excess amounts of material which may increase manufacturing costs, and may limit the amount of heat that is undesirably transferred to the frame rather than the aerosol-generating substrate.

[0109] The frame may be made from or comprise a biodegradable material. The frame may be made entirely from a biodegradable material.

[0110] The frame may be made from or comprise a cellulosic material. The cellulosic material may comprise a sheet of cellulosic material. The cellulosic material may comprise cellulose fibres. The cellulosic material may be paper, paperboard, or cardboard. The frame may be made from or comprise a plant material, such as tobacco. The frame may be made entirely from a cellulosic material.

[0111] The aerosol-generating article may comprise one or more susceptor materials. The frame may comprise one or more susceptor materials. The one more susceptor materials may be in thermal contact with the aerosol-generating substrate. The one more susceptor materials may be in thermal contact with at least one of the first cavity and the second cavity. The one or more susceptor materials may be incorporated within the material of the frame. For example, the one or more susceptor material may be incorporated within the peripheral wall of the frame.

[0112] The one or more susceptor materials may be one or more particles, strips, threads, or wires of susceptor material. The one or more susceptor materials may be one or more sheets or layers of susceptor material. The one of more sheets or layers of susceptor material may be in the form of a mesh of susceptor material.

[0113] The susceptor material, in whatever form, may comprise one or more materials selected from the list consisting of: aluminium, iron and iron alloys, nickel and nickel alloys, cobalt alloys, stainless steel alloys, copper alloys, carbon, expanded carbon, and graphite.

[0114] The frame may have a thickness greater than or equal to 50 percent of the thickness of the aerosol-generating article. The frame may have a thickness greater than or equal to 70 percent of the thickness of the aerosol-generating article. The frame may have a thickness greater than or equal to 90 percent of the thickness of the aerosol-generating article. The frame may have a thickness greater than or equal to 95 percent of the thickness of the aerosol-generating article.

[0115] The frame may have a thickness less than or equal to 95 percent of the thickness of the aerosolgenerating article. The frame may have a thickness less than or equal to 90 percent of the thickness of the aerosol-generating article. The frame may have a thickness less than or equal to 70 percent of the thickness of the aerosol-generating article.

[0116] The frame may have a thickness between 50 percent of the thickness of the aerosol-generating article and 95 percent of the thickness of the aerosol-generating article. The frame may have a thickness between 70 percent of the thickness of the aerosol-generating article and 95 percent of the thickness of the aerosol-generating article.

[0117] The frame may have a thickness greater than or equal to 1 millimetre, greater than or equal to 2 millimetres, greater than or equal to 3 millimetres, or greater than or equal to 4 millimetres. The frame may have a thickness less than or equal to 5.5 millimetres, less than or equal to 4.5 millimetres, less than or equal to 3.5 millimetres, less than or equal to 2.5 millimetres, or less than or equal to 1 .5 millimetres. The frame may have a thickness between 1 millimetre and 5.5 millimetres. Preferably, the frame may have a thickness between 1 .5 millimetres and 5.5 millimetres.

[0118] The frame may have a length that is equal to the length of the aerosol-generating article. The frame may have a length that is at least 90 percent of the length of the aerosol-generating article. The frame may have a length that is at least 95 percent of the length of the aerosol-generating article.

[0119] The frame may have a width that is equal to the width of the aerosol-generating article. The frame may have a width that is at least 90 percent of the width of the aerosol-generating article.

[0120] The frame may be a unitary component. Alternatively, the frame may comprise two or more layers. That is, the frame may have a laminated structure. Advantageously, the properties of each layer may be individually optimised depending on the relative distance between the layer and aerosolgenerating substrate or heater of the aerosol-generating device.

[0121] The frame may comprise a first frame layer and a second frame layer. The first frame layer and the second frame layer may be the only layers of the frame. That is, the frame may comprise no more than two layers or may comprise exactly two layers. The frame aperture may be defined through both the first frame layer and the second frame layer.

[0122] The frame may comprise a first frame layer, a second frame layer and a third frame layer. The second frame layer may be positioned between the first frame layer and the third frame layer. The first frame layer, the second frame layer and the third frame layer may be the only layers of the frame. That is, the frame may comprise no more than three layers or may comprise exactly three layers.

[0123] The aerosol-generating article may comprise an aerosol-generating substrate layer. Advantageously, the aerosol-generating substrate layer can be made thin and, therefore, quickly heat up and release volatile compounds to form an aerosol. Advantageously, the aerosol-generating substrate layer can be positioned close to a heater of an aerosol-generating device.

[0124] The aerosol-generating substrate layer may comprise an aerosol-generating material. The aerosol-generating material may be any aerosol-generating material described herein. The aerosolgenerating material may be in the form of a sheet of aerosol-generating material. The sheet of aerosolgenerating material may be any sheet of aerosol-generating material described herein. The aerosolgenerating substrate layer may be, and may be made entirely of, a sheet of aerosol-generating material.

[0125] The aerosol-generating substrate layer may be positioned between the frame and the first planar external surface. The aerosol-generating substrate layer may be positioned between the frame and the second planar external surface. The aerosol-generating substrate layer may be in physical contact with, and may be bonded to, the frame.

[0126] The aerosol-generating substrate layer may be positioned between the frame and the outer wrapper. The outer wrapper is discussed in more detail below. The aerosol-generating substrate layer may in physical contact with, and may be bonded to, both the frame and the outer wrapper.

[0127] The aerosol-generating substrate layer may be positioned between the frame and the first planar external layer. The aerosol-generating substrate layer may be positioned between the frame and the second planar external layer. The first planar external layer and the second planar external layer are discussed in more detail below. The aerosol-generating substrate layer may in physical contact with, and may be bonded to, both the frame and the first planar external layer. The aerosol-generating substrate layer may in physical contact with, and may be bonded to, both the frame and the second planar external layer.

[0128] The aerosol-generating substrate layer may overlie an end of the first cavity, second cavity, or both the first and second cavities. The aerosol-generating substrate layer may define or form a wall of the first cavity, second cavity, or both the first and second cavities, such as the first cavity end wall or the second cavity end wall. Advantageously, the aerosol-generating substrate layer may therefore be in, or at least partially define or form, the airflow passage thereby allowing released volatile compounds to quickly form an aerosol.

[0129] The aerosol-generating article may comprise a first aerosol-generating substrate layer and a second aerosol-generating substrate layer. Advantageously, a first and a second aerosol-generating substrate layer may allow rapid generation of a satisfactory volume of aerosol compared with using a single aerosol-generating substrate layer. The first aerosol-generating substrate layer may comprise an aerosol-generating material. The aerosol-generating material may be any aerosol-generating material described herein. The aerosolgenerating material may be in the form of a sheet of aerosol-generating material. The sheet of aerosolgenerating material may be any sheet of aerosol-generating material described herein. The first aerosolgenerating substrate layer may be, and may be made entirely of, a sheet of aerosol-generating material.

[0130] The second aerosol-generating substrate layer may comprise an aerosol-generating material. The aerosol-generating material may be any aerosol-generating material described herein. The aerosol-generating material may be in the form of a sheet of aerosol-generating material. The sheet of aerosol-generating material may be any sheet of aerosol-generating material described herein. The second aerosol-generating substrate layer may be, and may be made entirely of, a sheet of aerosolgenerating material.

[0131] The first aerosol-generating substrate layer may be positioned between the frame and the first planar external surface. The first aerosol-generating substrate layer may be in physical contact with, and may be bonded to, the frame.

[0132] The first aerosol-generating substrate layer may be positioned between the frame and the outer wrapper. The first aerosol-generating substrate layer may in physical contact with, and may be bonded to, both the frame and the outer wrapper.

[0133] The first aerosol-generating substrate layer may be positioned between the frame and the first planar external layer. The first aerosol-generating substrate layer may in physical contact with, and may be bonded to, both the frame and the first planar external layer.

[0134] The second aerosol-generating substrate layer may be positioned between the frame and the second planar external surface. The second aerosol-generating substrate layer may be in physical contact with, and may be bonded to, the frame.

[0135] The second aerosol-generating substrate layer may be positioned between the frame and the outer wrapper. The second aerosol-generating substrate layer may in physical contact with, and may be bonded to, both the frame and the outer wrapper.

[0136] The second aerosol-generating substrate layer may be positioned between the frame and the second planar external layer. The second aerosol-generating substrate layer may in physical contact with, and may be bonded to, both the frame and the second planar external layer.

[0137] The first aerosol-generating substrate layer and the second aerosol-generating substrate layer may overlie opposing ends of the first cavity, second cavity, or both the first and second cavities. The first aerosol-generating substrate layer and the second aerosol-generating substrate layer may define or form opposing end walls of the first cavity, second cavity, or both the first and second cavities. That is, the frame, the first aerosol-generating substrate layer and the second aerosol-generating substrate layer may collectively define the first cavity, second cavity, or both the first and second cavities.

[0138] One or more of the aerosol-generating substrate layer, the first aerosol-generating substrate layer and the second aerosol-generating substrate layer may have a thickness greater than or equal to 100 micrometres, greater than or equal to 200 micrometres, greater than or equal to 300 micrometres, greater than or equal to 400 micrometres, or greater than or equal to 500 micrometres. One or more of the aerosol-generating substrate layer, the first aerosol-generating substrate layer and the second aerosol-generating substrate layer may have a thickness less than or equal to 600 micrometres, less than or equal to 500 micrometres, less than or equal to 400 micrometres, less than or equal to 300 micrometres, or less than or equal to 300 micrometres.

[0139] One or more of the aerosol-generating substrate layer, the first aerosol-generating substrate layer and the second aerosol-generating substrate layer may have a thickness between 100 micrometres and 600 micrometres, between 200 micrometres and 500 micrometres, between 200 micrometres and 400 micrometres, or between 200 micrometres and 300 micrometres.

[0140] The aerosol-generating substrate layer may have a length substantially the same as the length of the frame. The aerosol-generating substrate layer may have a length substantially the same as the length of the aerosol-generating article.

[0141] The first aerosol-generating substrate layer may have a length substantially the same as the length of the frame. The first aerosol-generating substrate layer may have a length substantially the same as the length of the aerosol-generating article.

[0142] The second aerosol-generating substrate layer may have a length substantially the same as the length of the frame. The second aerosol-generating substrate layer may have a length substantially the same as the length of the aerosol-generating article.

[0143] The aerosol-generating substrate layer may have a width substantially the same as the width of the frame. The aerosol-generating substrate layer may have a width substantially the same as the width of the aerosol-generating article.

[0144] The first aerosol-generating substrate layer may have a width substantially the same as the width of the frame. The first aerosol-generating substrate layer may have a width substantially the same as the width of the aerosol-generating article.

[0145] The second aerosol-generating substrate layer may have a width substantially the same as the width of the frame. The second aerosol-generating substrate layer may have a width substantially the same as the width of the aerosol-generating article.

[0146] The first planar external surface may be a planar upper surface and the second planar external surface may be a planar lower surface. The first planar external surface may be positioned parallel to the second planar external surface. The first planar external surface may extend in the x / y plane. The second planar external surface may extend in the x / y plane. The second planar external surface may be spaced from the first planar external surface in the z-direction or transverse direction. The distance between the first planar external surface and the second planar external surface in the z-direction or transverse direction may define the thickness of the aerosol-generating article.

[0147] The aerosol-generating article may comprise an outer wrapper. The outer wrapper may be hydrophobic. The outer wrapper may comprise a hydrophobic material.

[0148] The outer wrapper may define or form the first planar external surface. The outer wrapper may define or form the second planar external surface. The outer wrapper may define or form both the first planar external surface and the second planar external surface.

[0149] The outer wrapper may circumscribe or encircle the frame. The outer wrapper may be in physical contact with, and may be bonded to, the frame. The outer wrapper may overlie opposing ends of the first cavity, second cavity, or both the first and second cavities. The outer wrapper may define or form opposing end walls of the first cavity, second cavity, or both the first and second cavities, such as the first cavity end wall and the second cavity end wall. That is, the frame and the outer wrapper may collectively define the first cavity, second cavity, or both the first and second cavities.

[0150] The outer wrapper may circumscribe or encircle the frame and the aerosol-generating substrate layer. The outer wrapper may be in physical contact with, and may be bonded to, both the frame and the aerosol-generating substrate layer.

[0151] The outer wrapper may circumscribe or encircle the frame, the first aerosol-generating substrate layer and the second aerosol-generating substrate layer. The outer wrapper may be in physical contact with, and may be bonded to, both the first aerosol-generating substrate layer and the second aerosol-generating substrate layer.

[0152] The aerosol-generating article may comprise a first planar external layer and a second planar external layer. The first planar external layer may be an upper layer and the second planar external layer may be a lower layer.

[0153] The first planar external layer may define or form the first planar external surface. The first planar external layer may extend in the x / y plane. The second planar external layer may define or form the second planar external surface. The second planar external layer may extend in the x / y plane.

[0154] The first planar external layer may be in physical contact with, and may be bonded to, the frame. The first planar external layer may overlie an end of the first cavity and second cavity. The first planar external layer may define or form a wall of the first cavity and second cavity, such as the first cavity end wall.

[0155] The second planar external layer may be in physical contact with, and may be bonded to, the frame. The second planar external layer may overlie an end of the first cavity and second cavity. The second planar external layer may define or form a wall of the first cavity and second cavity, such as the second cavity end wall.

[0156] The first planar external layer and the second planar external layer may overlie opposing ends of the first cavity and second cavity. The first planar external layer and the second planar external layer may define or form opposing end walls of the first cavity and second cavity, such as the first cavity end wall and the second cavity end wall. That is, the frame, the first planar external layer and the second planar external layer may collectively define the first cavity and the second cavity.

[0157] The first planar external layer may be spaced, such as in a transverse direction, from the frame. For example, the aerosol-generating substrate layer or the first aerosol-generating substrate layer may be positioned between the first planar external layer and the frame. The first planar external layer may be in physical contact with, and may be bonded to, the aerosol-generating substrate layer or the first aerosol-generating substrate layer.

[0158] The second planar external layer may be spaced, such as in a transverse direction, from the frame. For example, the aerosol-generating substrate layer or the second aerosol-generating substrate layer may be positioned between the second planar external layer and the frame. The second planar external layer may be in physical contact with, and may be bonded to, the aerosol-generating substrate layer or the second aerosol-generating substrate layer. The first planar external layer may be hydrophobic. The first planar external layer may comprise a hydrophobic material. The second planar external layer may be hydrophobic. The second planar external layer may comprise a hydrophobic material.

[0159] One or more of the outer wrapper, the first planar external layer and the second planar external layer may comprise, or be made from, a cellulosic material. The cellulosic material may be paper, cigarette paper, tobacco paper, cardboard, wood, textile, natural fibres or artificial fibres.

[0160] One or more of the outer wrapper, the first planar external layer and the second planar external layer may be an aerosol-generating substrate comprising an aerosol-generating material. The aerosolgenerating material may be any aerosol-generating material described herein. In particular, the aerosolgenerating material may be in the form of a sheet of aerosol-generating material. The sheet of aerosolgenerating material may be any sheet of aerosol-generating material described herein. Alternatively, one or more of the outer wrapper, the first planar external layer and the second planar external layer may not comprise any aerosol-generating material, particularly in embodiments comprising an aerosolgenerating substrate layer, a first aerosol-generating substrate layer, a second aerosol-generating substrate layer. One or more of the outer wrapper, the first planar external layer and the second planar external layer may be substantially nicotine-free.

[0161] One or more of the outer wrapper, the first planar external layer and the second planar external layer may have a thickness greater than or equal to 25 micrometres, greater than or equal to 30 micrometres, greater than or equal to 35 micrometres, greater than or equal to 40 micrometres, or greater than or equal to 45 micrometres.

[0162] One or more of the outer wrapper, the first planar external layer and the second planar external layer may have a thickness less than or equal to 55 micrometres, less than or equal to 50 micrometres, less than or equal to 45 micrometres, less than or equal to 40 micrometres, or less than or equal to 35 micrometres.

[0163] One or more of the outer wrapper, the first planar external layer and the second planar external layer may have a thickness between 25 micrometres and 55 micrometres, between 25 micrometres and 45 micrometres, or between 30 micrometres and 45 micrometres.

[0164] One or more of the outer wrapper, the first planar external layer and the second planar external layer may have a length substantially the same as the length of the frame. One or more of the outer wrapper, the first planar external layer and the second planar external layer may have a length substantially the same as the length of the aerosol-generating article.

[0165] One or more of the first planar external layer and the second planar external layer may have a width substantially the same as the width of the frame. One or more of the first planar external layer and the second planar external layer may have a width substantially the same as the width of the aerosol-generating article.

[0166] The first cavity may have a thickness greater than or equal to 0.5 millimetres. The first cavity may have a thickness greater than or equal to 1 .5 millimetres. The first cavity may have a thickness greater than or equal to 2.5 millimetres. The first cavity may have a thickness greater than or equal to 3.5 millimetres. The first cavity may have a thickness less than or equal to 4.5 millimetres. The first cavity may have a thickness less than or equal to 3.5 millimetres. The first cavity may have a thickness less than or equal to 2.5 millimetres. The first cavity may have a thickness less than or equal to 1 .5 millimetres.

[0167] The first cavity may have a thickness between 0.5 millimetres and 4.5 millimetres. The first cavity may have a thickness between 1 millimetre and 4.5 millimetres. Preferably, the first cavity may have a thickness between 2.8 millimetres and 3.3 millimetres.

[0168] The second cavity may have a thickness greater than or equal to 0.5 millimetres. The second cavity may have a thickness greater than or equal to 1 .5 millimetres. The second cavity may have a thickness greater than or equal to 2.5 millimetres. The second cavity may have a thickness greater than or equal to 3.5 millimetres.

[0169] The second cavity may have a thickness less than or equal to 4.5 millimetres. The second cavity may have a thickness less than or equal to 3.5 millimetres. The second cavity may have a thickness less than or equal to 2.5 millimetres. The second cavity may have a thickness less than or equal to 1 .5 millimetres.

[0170] The first cavity may have a thickness between 0.5 millimetres and 4.5 millimetres. The second cavity may have a thickness between 1 millimetre and 4.5 millimetres. Preferably, the second cavity may have a thickness between 2.8 millimetres and 3.3 millimetres.

[0171] The first cavity may have a width greater than or equal to 4.5 millimetres. The first cavity may have a width greater than or equal to 7 millimetres. The first cavity may have a width greater than or equal to 11 millimetres.

[0172] The first cavity may have a width less than or equal to 13 millimetres. The first cavity may have a width less than or equal to 11 millimetres. The first cavity may have a width less than or equal to 7 millimetres. The first cavity may have a width less than or equal to 5 millimetres.

[0173] The first cavity may have a width between 4.5 millimetres and 13 millimetres. The first cavity may have a width between 7 millimetres and 10 millimetres. The first cavity may have a width between

[0174] 7.5 millimetres and 8.5 millimetres.

[0175] The second cavity may have a width greater than or equal to 4.5 millimetres. The second cavity may have a width greater than or equal to 7 millimetres. The second cavity may have a width greater than or equal to 11 millimetres.

[0176] The second cavity may have a width less than or equal to 13 millimetres. The second cavity may have a width less than or equal to 11 millimetres. The second cavity may have a width less than or equal to 7 millimetres. The second cavity may have a width less than or equal to 5 millimetres.

[0177] The second cavity may have a width between 4.5 millimetres and 13 millimetres. The second cavity may have a width between 7 millimetres and 10 millimetres. The second cavity may have a width between 7.5 millimetres and 8.5 millimetres.

[0178] The first cavity may have a length between 6 millimetres and 16 millimetres, a width between

[0179] 4.5 millimetres and 13 millimetres, and a thickness between 0.5 millimetres and 4.5 millimetres.

[0180] Preferably, the first cavity may have a length between 8 millimetres and 14 millimetres, a width between 7 millimetres and 10 millimetres, and a thickness between 2.5 millimetres and 4 millimetres. Most preferably, the first cavity may have a length of 12 millimetres, a width of 8 millimetres, and a thickness of 3.1 millimetres.

[0181] The second cavity may have a length between 6 millimetres and 16 millimetres, a width between 4.5 millimetres and 13 millimetres, and a thickness between 0.5 millimetres and 4.5 millimetres.

[0182] Preferably, the second cavity may have a length between 8 millimetres and 14 millimetres, a width between 7 millimetres and 10 millimetres, and a thickness between 2.5 millimetres and 4 millimetres.

[0183] Most preferably, the second cavity may have a length of 12 millimetres, a width of 8 millimetres, and a thickness of 3.1 millimetres.

[0184] The first aerosol-generating substrate positioned within the first cavity may fill the first cavity.

[0185] The second aerosol-generating substrate positioned within the second cavity may fill the second cavity.

[0186] The first aerosol-generating substrate, the second aerosol-generating substrate, preferably both the first aerosol-generating substrate and the second aerosol-generating substrate may comprise an aerosol-generating material.

[0187] Preferably, the first aerosol-generating substrate is in the form of a plug. Preferably, the second aerosol-generating substrate is in the form of a plug. The plug of the first aerosol-generating element may comprise aerosol-generating material form into a plug of aerosol-forming material. The plug of the first aerosol-generating element may comprise aerosol-generating material circumscribed by a wrapper to form a plug. The plug of the second aerosol-generating element may comprise aerosol-generating material form into a plug of aerosol-forming material. The plug of the second aerosol-generating element may comprise aerosol-generating material circumscribed by a wrapper to form a plug.

[0188] The aerosol-generating material may be any aerosol-generating material described herein. For example, the aerosol-generating material may be in the form of shredded aerosol-generating material.

[0189] The aerosol-generating material may be in the form of a sheet of aerosol-generating material. The sheet of aerosol-generating material may be any sheet of aerosol-generating material described herein. For example, the sheet of aerosol-generating material may be a sheet of homogenised tobacco material.

[0190] The sheet of aerosol-generating material may extend the entire length of the first cavity, the second cavity or both the first and second cavity. The sheet of aerosol-generating material may extend the entire width of the first cavity, the second cavity or both the first and second cavity.

[0191] The sheet of aerosol-generating material may be a gathered sheet of aerosol-generating material. That is, the sheet of aerosol-generating material may be convoluted, folded, or otherwise compressed or constricted substantially perpendicular to the transverse direction of the aerosolgenerating article.

[0192] The sheet of aerosol-generating material may be a crimped sheet of aerosol-generating material. The sheet of aerosol-generating material may be a corrugated sheet of aerosol-generating material. The crimped sheet of aerosol-generating material or the corrugated sheet of aerosol- generating material may comprise a plurality of parallel corrugations. For example, the crimped sheet of aerosol-generating material may comprise a plurality of substantially parallel peaks and troughs.

[0193] The plurality of parallel corrugations may be defined by a corrugation profile, in which the corrugation profile is sinusoidal, or triangular, or rectangular, or trapezoidal, or toroidal, or parabolic.

[0194] The plurality of parallel corrugations may define, or form, a plurality of channels between the sheet of aerosol-generating material and one or more walls of at least one of the first cavity and the second cavity. The plurality of channels may be a plurality of longitudinally extending channels. The plurality of channels may be a plurality of laterally extending channels. The plurality of channels may defined, or form, at least a portion of the airflow passage extending between the air inlet and air outlet of the aerosol-generating article.

[0195] Preferably, the first aerosol-forming substrate comprises a different aerosol-generating material to the second aerosol-forming substrate.

[0196] The aerosol-generating material may comprise one or more organic materials such as tobacco, mint, tea and cloves. The aerosol-generating material may comprise one or more of: herb leaf, tobacco leaf, fragments of tobacco ribs, reconstituted tobacco, homogenised tobacco such as cast leaf, extruded tobacco, expanded tobacco, aerosol-generating films and gel compositions.

[0197] The aerosol-generating material may be in the form of shredded aerosol-generating material. The shredded aerosol-generating material may comprise one or more of: strips and strands of aerosolgenerating material, such as strips and strands of tobacco or homogenised tobacco material. The shredded aerosol-generating material may be in the form of a shredded sheet of homogenised tobacco material.

[0198] The aerosol-generating material may be cut filler. The aerosol-generating material may be tobacco cut filler. As used herein, the term “cut filler” is used to describe to a blend of shredded plant material, such as tobacco plant material, including, in particular, one or more of leaf lamina, processed stems and ribs, homogenised plant material.

[0199] The aerosol-generating material may be in the form of a sheet of aerosol-generating material. As used herein, the term “sheet” describes a laminar element having a width and length substantially greater than the thickness thereof. The sheet of aerosol-generating material may be a sheet of plant material. The sheet of aerosol-generating material may be a sheet of tobacco material. The sheet of aerosol-generating material may be a sheet of homogenised tobacco material, such as a cast leaf sheet.

[0200] Optionally, the aerosol-forming material comprises hydroxypropylmethyl cellulose. Optionally, the aerosol-forming material comprises one or more cellulose-based strengthening agents. Optionally, the aerosol-forming material comprises hydroxypropyl methyl cellulose and one or more cellulose-based strengthening agents. Optionally, the aerosol-forming material comprises hydroxypropylmethyl cellulose and one or more cellulose-based strengthening agents, and preferably also one or both of: is tobacco-free; and comprises one or more aerosol formers. Thus, optionally, the aerosol-forming material comprises hydroxypropylmethyl cellulose and one or more cellulose-based strengthening agents, is tobacco-free, and also comprises one or more aerosol formers.

[0201] An aerosol-forming substrate that includes hydroxypropylmethyl cellulose and one or more cellulose-based strengthening agent may have a number of advantages. The inclusion of hydroxypropylmethyl cellulose in the aerosol-forming substrate may improve the manufacturing process of the aerosol-forming substrate. For example, hydroxypropylmethyl cellulose may reduce the viscosity of the slurry that is mixed when making the aerosol-forming substrate. A lower viscosity slurry may flow more easily compared to conventional slurries, and a lower viscosity slurry is easier to mix, transfer and handle during the manufacturing process.

[0202] The inclusion of a cellulose-based strengthening agent in the aerosol-forming substrate may increase the tensile strength of the aerosol-forming substrate. This may be particularly beneficial if hydroxypropylmethyl cellulose is present because hydroxypropylmethyl cellulose can reduce the tensile strength of the substrate. An aerosol-forming substrate with a higher tensile strength may be less likely to deteriorate or break, for example during transit or during the manufacturing process.

[0203] Optionally, the aerosol-forming substrate comprises, on a dry weight basis, at least 0.5, 1 , 5, 10, 15 or 20 weight percent hydroxypropylmethyl cellulose. Optionally, the aerosol-forming substrate comprises, on a dry weight basis, no more than 50, 45, 40, 35, 30, 25 or 20 weight percent hydroxypropylmethyl cellulose. It may be preferable for the aerosol-forming substrate to comprise, on a dry weight basis, between 5 and 50, more preferably between 10 and 50, most preferably between 20 and 50 weight percent hydroxypropylmethyl cellulose.

[0204] Optionally, the aerosol-forming substrate comprises, on a dry weight basis, at least 0.5, 1 , 5, 10, 15 or 20 weight percent of the one or more cellulose-based strengthening agents.

[0205] Optionally, the aerosol-forming substrate comprises, on a dry weight basis, no more than 50, 45, 40, 35, 30, 25 or 20 weight percent of the one or more cellulose-based strengthening agents. It may be preferable for the aerosol-forming substrate to comprise, on a dry weight basis, between 5 and 50, more preferably between 10 and 50, most preferably between 20 and 50 weight percent of the one or more cellulose-based strengthening agents.

[0206] The one or more cellulose-based strengthening agents may comprise or consist of one or more of: cellulose fibres, microcrystalline cellulose, and cellulose powder. Advantageously, such cellulose- based strengthening agents may be particularly effective at increasing the tensile strength of an aerosolforming substrate.

[0207] Preferably, the first aerosol-forming substrate comprises tobacco and the second aerosolforming substrate is substantially free of tobacco. Preferably, the second aerosol-forming substrate comprises tobacco and the first aerosol-forming substrate is substantially free of tobacco.

[0208] The aerosol-generating material may comprise one or more aerosol-formers. Suitable aerosolformers are well known in the art and include, but are not limited to, one or more aerosol-formers selected from: polyhydric alcohols, such as propylene glycol, polyethylene glycol, 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. It may be particularly preferable for the aerosol-former to be or comprise one or both of glycerine and propylene glycol. The aerosol former may consist of glycerine or propylene glycol or of a combination of glycerine and propylene glycol.

[0209] The aerosol-generating material may have an aerosol-former content greater than or equal to 1 , 2, 5, 10, or 15 percent by weight on a dry weight basis. The aerosol-generating material may have an aerosol-former content greater than or equal to 15 percent by weight on a dry weight basis, for example greater than 20 by weight on a dry weight basis, or greater than 25 by weight on a dry weight basis, or greater than 30 by weight on a dry weight basis, or greater than 40 by weight on a dry weight basis, or greater than 50 by weight on a dry weight basis.

[0210] The aerosol-generating material may have an aerosol-former content less than or equal to 30 percent by weight on a dry weight basis, less than or equal to 25 percent by weight on a dry weight basis, or less than or equal to 20 percent by weight on a dry weight basis.

[0211] The aerosol-generating material may have an aerosol-former content between 5 percent and 30 percent by weight on a dry weight basis, between 5 percent and 25 percent by weight on a dry weight basis, or between 5 percent and 20 percent by weight on a dry weight basis.

[0212] The aerosol-generating material may have an aerosol-former content between 10 percent and 30 percent by weight on a dry weight basis, between 10 percent and 25 percent by weight on a dry weight basis, or between 10 percent and 20 percent by weight on a dry weight basis.

[0213] The aerosol-generating material may comprise nicotine. The aerosol-generating material may comprise natural nicotine, or synthetic nicotine, or a combination of natural nicotine and synthetic nicotine.

[0214] The aerosol-generating material may comprise at least 0.5 percent by weight of nicotine, at least 1 percent by weight of nicotine, at least 1 .5 percent by weight of nicotine, or at least 2 percent by weight of nicotine. That is, the aerosol-generating material may have a nicotine content of at least 0.5 percent by weight, at least 1 percent by weight, at least 1 .5 percent by weight, or at least 2 percent by weight.

[0215] The aerosol-generating material may be in the form of a plurality of beads. The plurality of beads may have an average particle diameter of between 0.1 mm and 4 mm, for example between 0.5 mm and 4 mm.

[0216] The term “bead” refers to a discrete, solid particle formed of the aerosol-generating substrate. A bead may have a rounded, typically spherical, form. Other terms may be used to define the substrate such as, for example, “granule”.

[0217] Providing the aerosol-generating material as a plurality of beads may provide certain advantages. Beads can be easily handled compared to other aerosol-forming substrates such as fine powders or cut filler. The beads flow easily, and so can reliably and consistently fill at least one of the first cavity and the second cavity of the aerosol-generating article during manufacture. This may allow a consistent and reproducible amount of aerosol-forming substrate to be loaded into each article during manufacture. Beads may also be cleaner to handle than powders and cut fillers, which may cause dust in factories, and may leak from aerosol-generating articles in transit or in use. By selecting beads with appropriate bead sizes and appropriate particle size distributions, air flow through the first cavity and the second cavity of the aerosol-generating article may be controlled more reproducibly than would be the case for, say, a cut filler substrate.

[0218] Where a particle is not perfectly spherical, but a diameter of the particle is referred to, the term “diameter” may refer to a largest dimension of the particle. Alternatively, the term “diameter” may refer to the diameter of a perfectly spherical particle having the same volume as the not perfectly spherical particle.

[0219] The term “average particle diameter”, as used herein, may refer to a number average particle diameter. Other methods of determining average particle diameter are known. Thus, the average particle diameter may be, for example, a volume average particle diameter.

[0220] The aerosol-forming substrate may comprise one or more flavourants. The one or more flavourants may comprise one or more of: one or more essential oils such as eugenol, peppermint oil and spearmint oil; one or both of menthol and eugenol; one or both of anethole and linalool; and a herbaceous material. Suitable herbaceous material includes herb leaf or other herbaceous material from herbaceous plants including, but not limited to, mints, such as peppermint and spearmint, lemon balm, basil, cinnamon, lemon basil, chive, coriander, lavender, sage, tea, thyme, and caraway. The one or more flavourants may comprise a tobacco material.

[0221] The aerosol-forming substrate may comprise one or more botanicals. For example, the aerosolforming substrate may comprise about 1 to 90 %, for example about 15 to 55 %, preferably of about 20 to 35 %, of botanicals such as Clove, Echinacea sp., Fennel, Ginger, Hawthorn berry, Elderberry, Monarda, Mullein leaves, Nettle, Plantain, Turmeric, Yarrow, Rooibos, Star Anise, Thyme, Anethum, Chamomile and compounds of those.

[0222] The aerosol-forming substrate may have a moisture content of about 5 to 25%, preferably of about 7 to 15%, at final product state. For example, the aerosol-forming substrate may be a homogenised tobacco material with a moisture of about 5 to 25%, preferably of about 7 to 15%, at final product state.

[0223] The aerosol-forming substrate may comprise a binder. For example, the aerosol-forming substrate may comprise about 1 to 10%, preferably of about 1 to 5%, of a binder such as any of common gums or pectins used in food and beverage (F&B) industries. Preferred binders may be natural pectins, such as fruit, for example citrus, or tobacco pectins; guar gums, land locust bean gums, such as hydroxyethyl and / or hydroxypropyl of those; starches, such as modified or derivatized starches; alginate; methyl, ethyl, ethylhydroxymethyl and carboxymethyl, celluloses; dextran; and xanthan gum. A preferable binder is guar.

[0224] The aerosol-forming substrate may comprise, or consist of, a solid aerosol-forming material. The aerosol-forming substrate may comprise a liquid aerosol-forming material, for example a liquid aerosolforming material retained within a porous matrix. The aerosol-forming substrate may comprise a gel aerosol-forming material.

[0225] All of the features above relating to an aerosol-forming substrate, such as what the aerosolforming substrate may comprise, are equally applicable to the first aerosol-forming substrate, the second aerosol-forming substrate, and the third aerosol-forming substrate. The aerosol-forming substrate, the second aerosol-forming substrate, and the third aerosol-forming substrate may have substantially identical or different compositions. For example, the aerosol-forming substrate and the second aerosol-forming may comprise different flavourants. The aerosol-generating material may be in form of a wrapped body of aerosol-generating material, the wrapped body comprising a wrapper at least partially enclosing aerosol-generating material.

[0226] The wrapped body of aerosol-generating material may occupy between 15% and 100% of the interior volume of the first cavity or the second cavity. The wrapped body of aerosol-generating material may occupy between 30% and 100% of the interior volume of the first cavity or the second cavity. The wrapped body of aerosol-generating material may occupy between 50% and 100% of the interior volume of the first cavity or the second cavity. The wrapped body of aerosol-generating material may occupy between 50% and 80% of the interior volume of the first cavity or the second cavity. The wrapped body of aerosol-generating material may occupy between 50% and 70% of the interior volume of the first cavity or the second cavity.

[0227] The air inlet may be defined by a front wall of the aerosol-generating article. The air inlet may be defined by, and may extend through, the frame. The air inlet may be defined by the peripheral wall of the frame. The air inlet may extend through the peripheral wall of the frame. The air outlet may be defined by a back wall of the aerosol-generating article. The air outlet may be defined by, and may extend through, the frame. The air outlet may be defined by the peripheral wall of the frame. The outlet may extend though the peripheral wall of the frame.

[0228] The air inlet may have a round cross-section, a circular cross-section, an oval cross-section, a square cross-section, or a rectangular cross-section. The air outlet may have a round cross-section, a circular cross-section, an oval cross-section, a square cross-section, or a rectangular cross-section.

[0229] The air inlet may be defined by, and may extend through, the first planar external surface. The air inlet may be defined by, and may extend through, the outer wrapper. The air inlet may be defined by, and may extend through, the outer wrapper and the aerosol-generating substrate layer. The air inlet may be defined by, and may extend through, the outer wrapper and the first aerosol-generating substrate layer. The air inlet may be defined by, and may extend through, the first planar external layer and the aerosol-generating substrate layer. The air inlet may be defined by, and may extend through, the first planar external layer and the first aerosol-generating substrate layer.

[0230] The air inlet may be defined by, and may extend through, the second planar external surface. The air inlet may be defined by, and may extend through, the outer wrapper and the second aerosolgenerating substrate layer. The air inlet may be defined by, and may extend through, the second planar external layer and the aerosol-generating substrate layer. The air inlet may be defined by, and may extend through, the second planar external layer and the second aerosol-generating substrate layer.

[0231] The air outlet may be defined by, and may extend through, the first planar external surface. The air outlet may be defined by, and may extend through, the outer wrapper. The air outlet may be defined by, and may extend through, the outer wrapper and the aerosol-generating substrate layer. The air outlet may be defined by, and may extend through, the outer wrapper and the first aerosol-generating substrate layer. The air outlet may be defined by, and may extend through, the first planar external layer and the aerosol-generating substrate layer. The air outlet may be defined by, and may extend through, the first planar external layer and the first aerosol-generating substrate layer. The air outlet may be defined by, and may extend through, the second planar external surface. The air outlet may be defined by, and may extend through, the outer wrapper and the second aerosolgenerating substrate layer. The air outlet may be defined by, and may extend through, the second planar external layer and the aerosol-generating substrate layer. The air outlet may be defined by, and may extend through, the second planar external layer and the second aerosol-generating substrate layer.

[0232] One or both of the air inlet and the air outlet may have an equivalent diameter greater than or equal to 0.1 millimetres, greater than or equal to 0.4 millimetres, greater than or equal to 0.7 millimetres, or greater than or equal to 1 .0 millimetres.

[0233] One or both of the air inlet and the air outlet may have an equivalent diameter less than or equal to 3 millimetres, less than or equal to 2.7 millimetres, less than or equal to 2.4 millimetres, less than or equal to 2.1 millimetres. The air inlet may have an equivalent diameter less than or equal to 2.7 millimetres, less than or equal to 1 .8 millimetres, or less than or equal to 1 .5 millimetres.

[0234] One or both of the air inlet and the air outlet may have an equivalent diameter between 0.1 millimetres and 3 millimetres, between 0.1 millimetres and 2.4 millimetres, between 0.4 millimetres and 2.1 millimetres, between 0.4 millimetres and 1 .8 millimetres, between 0.7 millimetres and 1 .5 millimetres, or between 1 .0 millimetres and 1 .5 millimetres.

[0235] The air inlet may have a width less than a width of the first cavity, the second cavity, or both the first and second cavity. The air outlet may have a width less than a width of the first cavity, the second cavity, or both the first and second cavity. The air inlet may have a thickness less than a thickness of the first cavity, the second cavity, or both the first and second cavity. The air outlet may have a thickness less than a thickness of the first cavity, the second cavity, or both the first and second cavity.

[0236] One or both of the air inlet and the air outlet may a width of between 0.3 millimetres and 3 millimetres or between 0.5 millimetres and 2 millimetres.

[0237] One or both of the air inlet and the air outlet may have a thickness of between 0.3 millimetres and 3 millimetres or between 0.5 millimetres and 2 millimetres.

[0238] Preferably, the air inlet may have a width of between 0.3 millimetres and 3 millimetres, and a thickness of between 0.3 millimetres and 3 millimetres.

[0239] Preferably, the air outlet may have a width of between 0.3 millimetres and 3 millimetres, and a thickness of between 0.3 millimetres and 3 millimetres.

[0240] Advantageously, an aerosol-generating article having an air outlet or air inlet with a width of between 0.3 millimetres and 3 millimetres and a thickness of between 0.3 millimetres and 3 millimetres may provide for a relatively large inlet or outlet opening while allowing for improved retention of the aerosol-generating substrate within the aerosol-generating article. Improved retention of the aerosolgenerating substrate within the aerosol-generating article may reduce the risk of aerosol-generating substrate falling out of the aerosol-generating article.

[0241] A ratio of the width of the air inlet to the thickness of the air inlet may be between 0.33 and 3. A ratio of the width of the air inlet to the thickness of the air inlet may be between 0.5 and 1 .5. A ratio of the width of the air inlet to the thickness of the air inlet may be between 0.75 and 1 .25. A ratio of the width of the air outlet to the thickness of the air outlet may be between 0.33 and 3. A ratio of the width of the air outlet to the thickness of the air outlet may be between 0.5 and 1 .5. A ratio of the width of the air outlet to the thickness of the air outlet may be between 0.75 and 1 .25.

[0242] The aerosol-generating article may comprise a plurality of air inlets. One or each of the air inlets may have one or more of the features of the air inlet described herein.

[0243] The aerosol-generating article may comprise a plurality of air outlets. One or each of the air outlets may have one or more of the features of the air outlet described herein.

[0244] The aerosol-generating article may comprise a filter element positioned downstream of the first and second aerosol-forming substrates. The aerosol-generating article may comprise a filter element positioned downstream of the first cavity. The aerosol-generating article may comprise a filter element at least partially positioned within the air outlet. The aerosol-generating article may comprise a filter element positioned within, and may be positioned at a downstream end of, the first cavity.

[0245] The aerosol-generating article may comprise a filter element positioned upstream of the first and second aerosol-forming substrates. The aerosol-generating article may comprise a filter element positioned upstream of the second cavity. The aerosol-generating article may comprise a filter element at least partially positioned within the air inlet. The aerosol-generating article may comprise a filter element positioned within, and may be positioned at an upstream end of, the second cavity.

[0246] The filter element may comprise one or more segments of a fibrous filtration material. Suitable fibrous filtration materials would be known to the skilled person. The filter element may comprise a cellulose acetate.

[0247] A ratio between the length and the thickness of the aerosol-generating article, and between the width and the thickness of the aerosol-generating article may be greater than 2:1 , greater than 5:1 , greater than 10:1 , greater than 12:1 , or greater than 15:1 .

[0248] A ratio between the length and the thickness of the aerosol-generating article, and between the width and the thickness of the aerosol-generating article may be less than 15:1 , less than 12:1 , less than 10:1 , less than 5:1 , or less than 2.5:1

[0249] A ratio between the length and the thickness of the aerosol-generating article, and between the width and the thickness of the aerosol-generating article may be between 2:1 and 15:1 , between 2:1 and 12:1 , between 2:1 and 10:1 , or between 5:1 and 10:1 .

[0250] A ratio between the length and the width of the aerosol-generating article may be greater than 1 :1 , greater than 2:1 , greater than 3:1 , greater than 4:1 , or greater than 5:1 .

[0251] A ratio between the length and the width of the aerosol-generating article may be less than 10:1 , less than 8:1 , less than 5:1 , less than 4:1 , less than 3:1 , or less than 2:1 .

[0252] A ratio between the length and the width of the aerosol-generating article may be between 1 :1 and 10:1 , between 1 :1 and 5:1 , between 1 :1 and 4:1 , between 1 :1 and 3:1 , between 2:1 and 4:1 , or between 2:1 and 3:1 .

[0253] The aerosol-generating article may have a length greater than or equal to 15 millimetres, greater than or equal to 20 millimetres, greater than or equal to 25 millimetres, greater than or equal to 30 millimetres, greater than or equal to 35 millimetres, or greater than or equal to 40 millimetres. The aerosol-generating article may have a length less than or equal to 45 millimetres, less than or equal to 40 millimetres, less than or equal to 35 millimetres, or less than or equal to 30 millimetres.

[0254] The aerosol-generating article may have a length between 15 millimetres and 45 millimetres, between 20 millimetres and 40 millimetres, between 20 millimetres and 35 millimetres, or between 25 millimetres and 30 millimetres.

[0255] The aerosol-generating article may have a width equal to greater than 3 millimetres, greater than 5 millimetres, greater than 7.5 millimetres, greater than 9 millimetres, greater than 11 millimetres, or greater than 13 millimetres.

[0256] The aerosol-generating article may have a width less than or equal to 17 millimetres, less than or equal to 15 millimetres, less than or equal to 12.5 millimetres, less than or equal to 11 millimetres, or less than or equal to 9 millimetres.

[0257] The aerosol-generating article may have a width between 3 millimetres and 17 millimetres, between 5 millimetres and 15 millimetres, between 7.5 millimetres and 12.5 millimetres, or between 9 millimetres and 11 millimetres.

[0258] The aerosol-generating article may have a thickness equal to greater than 1 millimetre, greater than or equal to 1 .5 millimetres, greater than or equal to 2 millimetres, greater than or equal to 2.5 millimetres, greater than or equal to 3 millimetres, greater than or equal to 3.5 millimetres, greater than or equal to 4 millimetres, or greater than or equal to 4.5 millimetres.

[0259] The aerosol-generating article may have a thickness less than or equal to 5.5 millimetres, less than or equal to 5 millimetres, less than or equal to 4.5 millimetres, less than or equal to 4 millimetres, less than or equal to 3.5 millimetres, less than or equal to 3 millimetres, less than or equal to 2.5 millimetres, or less than or equal to 2 millimetres.

[0260] The aerosol-generating article may have a thickness between 1 millimetres and 5 millimetres, between 1 .5 millimetres and 5 millimetres, between 2 millimetres and 4.5 millimetres, between 2.5 millimetres and 4 millimetres, or between 3 millimetres and 3.5 millimetres.

[0261] Preferably, the aerosol-generating article comprises an engagement element configured to engage with a portion of an aerosol-generating device when the aerosol-generating article is received by the aerosol-generating device.

[0262] The engagement element may be formed or situated on or at an external surface of the aerosolgenerating article. For example, the engagement element may be formed or situated on or at the frame outer surface.

[0263] The engagement element may comprise at least one protrusion, at least one depression, or both at least one protrusion, and at least one depression. The at least one protrusion, the at least one depression, or both the at least one protrusion, and the at least one depression may be configured to engage with corresponding protrusions and depressions formed or situated on the aerosol-generating device.

[0264] Advantages of, the engagement element may provide a more secure engagement between the aerosol-generating article and the aerosol-generating device.

[0265] Preferably, the engagement element is configured to provide at least two stable positions for the aerosol-generating article within an aerosol-generating device. Preferably, the engagement element is configured to provide a first stable position in which the first aerosol-generating substrate is aligned with a heater of the aerosol-generating device. In the first stable position, the first aerosol-generating substrate is configured to be heated by the heater to generate an aerosol from the first aerosol-generating substrate. Preferably, in the first stable position the second aerosol-generating substrate is not aligned with the heater of the aerosol-generating device and so the second aerosol-generating substrate is not configured to be heated in the first stable position.

[0266] Preferably, the engagement element is configured to provide a second stable position in which the second aerosol-generating substrate is aligned with the heater of the aerosol-generating device. In the second stable position, the second aerosol-generating substrate is configured to be heated by the heater to generate an aerosol from the second aerosol-generating substrate. Preferably, in the second stable position the first aerosol-generating substrate is not aligned with the heater of the aerosolgenerating device and so the first aerosol-generating substrate is not configured to be heated in the second stable position.

[0267] According to the present disclosure, there is provided an aerosol-generating device for receiving an aerosol-generating article as disclosed herein. The aerosol-generating device comprises a cavity dimensioned to receive at least a portion of the aerosol-generating article. The aerosolgenerating device comprises a heater or heating means, a power source for supplying power to the heater or heating means, and a controller to control a supply of power to the heater or heating means. The aerosol-generating device is configured to heat at least one of the one or more aerosol-generating substrates to form an aerosol, for example an inhalable aerosol. The aerosol-generating device may be configured to heat each of the one or more aerosol-generating substrates to form an aerosol, for example an inhalable aerosol.

[0268] Preferably, the aerosol-generating device is configured to heat the first aerosol-generating substrate, the second aerosol forming substate, or both the first aerosol-generating substrate and the second aerosol forming substate. The aerosol-generating device may be configured to heat both the first aerosol-generating substrate and the second aerosol forming substate together or separately.

[0269] According to the present disclosure, an aerosol-generating system comprises an aerosolgenerating device as disclosed herein and an aerosol-generating article as disclosed herein. The system may comprise a plurality of such articles for use with the aerosol-generating device.

[0270] The aerosol-generating device may be configured to engage with, and generate an aerosol from, the aerosol-generating article.

[0271] Preferably, the aerosol-generating device comprises a heater configured to heat at least one of the first aerosol-generating substrate and the second aerosol-generating substrate. Preferably, the heater is configured to heat both the first aerosol-generating substrate and the second aerosol forming substate together or separately.

[0272] Preferably, the aerosol-generating system is actuatable between a first stable position in which the heater is aligned with, and configured to generate aerosol from, the first aerosol-forming substrate and a second stable position, in which the heater is aligned with, and configured to generate aerosol from, the second aerosol-forming substrate. As used herein, the term “aerosol-generating article” refers to an article comprising an aerosolgenerating substrate. The article may be heated in use to produce and deliver an inhalable aerosol to a consumer.

[0273] As used herein, the term “aerosol-generating substrate” refers to a substrate capable of releasing volatile compounds upon heating, for example compounds which, in use, cool and condense to generate an aerosol.

[0274] As used herein, the term “aerosol-generating device” refers to a device that, in use, interacts with, for example heats, an aerosol-generating substrate of an aerosol-generating article to generate an aerosol.

[0275] As used herein, the term “planar” refers to a feature generally formed in a single Euclidean plane and not wrapped around or otherwise conformed to fit a curved or other non-planar shape. A planar surface may extend in two dimensions in a single Euclidean plane. A planar object may extend in two dimensions in a single Euclidean plane substantially more than in a third dimension perpendicular to the plane. More specifically, a planar object may extend in a first dimension and a second dimension perpendicular to the first dimension at least two, five or ten times further than the object extends in a third dimension perpendicular to the first and second dimensions.

[0276] As used herein, the term “transverse” refers to a direction extending between the first planar external surface and the second planar external surface. The transverse direction may also be referred to as the “z-direction”.

[0277] As used herein, the term “longitudinal” refers to a direction that is perpendicular to the transverse direction. For example, a direction between a front wall and a backwall of the aerosol-generating article. The longitudinal direction may also be referred to as the “x-direction”.

[0278] As used herein, the term “lateral” refers to a direction that is perpendicular to the transverse direction and the longitudinal direction. For example, a direction from a first side wall to a second side wall of the aerosol-generating article. The lateral direction may also be referred to as the “y-direction”.

[0279] As used herein, the term “thickness” refers to a maximum dimension of the aerosol-generating article or a component of the aerosol-generating article in the transverse direction.

[0280] As used herein, the term “length” refers to a maximum dimension of the aerosol-generating article or a component of the aerosol-generating article in the longitudinal direction.

[0281] As used herein, the term “width” refers to a maximum dimension of the aerosol-generating article or a component of the aerosol-generating article in the lateral direction.

[0282] As used herein, the terms “upstream” and “downstream” refer to the relative positions of components, or portions of components, of the aerosol-generating article in relation to the direction in which the air or aerosol is transported through the aerosol-generating article during use.

[0283] As used herein, the term “bulk density” may refer to the total weight of the aerosol-generating substrate divided by the bulk volume of the aerosol-generating substrate.

[0284] As used herein, the term “aerosol former” may refer to any suitable known compound or mixture of compounds that, in use, facilitates formation of an aerosol. The aerosol may be a dense and stable aerosol. The aerosol may be substantially resistant to thermal degradation at the operating temperature of the aerosol-generating substrate or aerosol-generating article. As used herein, the term “aerosol former content” may refer to aerosol former content in percent on a dry weight basis, unless otherwise specified.

[0285] As used herein, a "susceptor" refers to a conductive element that heats up when subjected to a changing magnetic field. This may be the result of eddy currents induced in the susceptor element and / or hysteresis losses.

[0286] As used herein, the term “hydrophobic” refers to a surface exhibiting water repelling properties. One useful way to determine this is to measure the water contact angle. The “water contact angle” is the angle, conventionally measured through the liquid, where a liquid / vapour interface meets a solid surface. It quantifies the wettability of a solid surface by a liquid via the Young equation.

[0287] As used herein, the term “equivalent diameter” of an opening or an aperture is used herein to denote the diameter of a circular opening or aperture having the same cross-sectional area as the opening or aperture.

[0288] 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 aspect described herein.

[0289] Ex1 . An aerosol-generating article for use with an aerosol-generating device to generate an aerosol, the aerosol-generating article comprising: a first cavity and a second cavity, in which the second cavity is located in series with the first cavity; a first aerosol-generating substrate positioned in the first cavity; a second aerosol-generating substrate different to the first aerosol-forming substrate and positioned in the second cavity; an air inlet, an air outlet, and an airflow passage extending between the air inlet and the air outlet through the first cavity and the second cavity; a first planar external surface and a second planar external surface; and a frame positioned between the first planar external surface and the second planar external surface, wherein the frame at least partially defines the first cavity and the second cavity.

[0290] Ex1 a. The aerosol-generating article according to example Ex1 , in which the second cavity is located upstream of the first cavity;

[0291] Ex1 b. The aerosol-generating article according to example Ex1 , in which the airflow passage comprises a restriction between the first cavity and the second cavity.

[0292] Ex2. The aerosol-generating article according to example Ex1 b, in which the frame comprises a dividing wall which separates the first cavity and the second cavity, in which the dividing wall defines or forms an aperture, and in which the aperture defines the restriction of the airflow passage between the air inlet and the air outlet.

[0293] Ex3. The aerosol-generating article according to any preceding example, in which the first cavity has a different volume to the second cavity.

[0294] Ex4. The aerosol-generating article according to any preceding example, in which the volume of the first cavity is greater than 100 cubic millimetres, for example greater than 200 cubic millimetres, for example greater than 300 cubic millimetres. Ex5. The aerosol-generating article according to any preceding example, in which the volume of the first cavity is less than 600 cubic millimetres, for example less than 500 cubic millimetres, for example less than 400 cubic millimetres.

[0295] Ex6. The aerosol-generating article according to any preceding example, in which the volume of the second cavity is greater than 100 cubic millimetres, for example greater than 200 cubic millimetres, for example greater than 300 cubic millimetres.

[0296] Ex7. The aerosol-generating article according to any preceding example, in which the volume of the second cavity is less than 600 cubic millimetres, for example less than 500 cubic millimetres, for example less than 400 cubic millimetres.

[0297] Ex8. The aerosol-generating article according to any preceding example, in which the first cavity has a different length to the second cavity.

[0298] Ex9. The aerosol-generating article according to any preceding example, in which the first cavity has a length of at least 5 millimetres, for example a length of at least 6 millimetres, for example a length of at least 7 millimetres.

[0299] Ex10. The aerosol-generating article according to any preceding example, in which the first cavity has a length of less than 30 millimetres, for example a length of less than 25 millimetres, for example a length less than 20 millimetres, for example a length of less than 12 millimetres.

[0300] Ex11 . The aerosol-generating article according to any preceding example, in which the second cavity has a length of at least 5 millimetres, for example a length of at least 6 millimetres, for example a length of at least 7 millimetres.

[0301] Ex12. The aerosol-generating article according to any preceding example, in which the second cavity has a length of less than 30 millimetres, for example a length of less than 25 millimetres, for example a length less than 20 millimetres, for example a length of less than 12 millimetres.

[0302] Ex13. The aerosol-generating article according to any preceding example, in which the first aerosolgenerating substrate has a different aerosol former content than the second aerosol-generating substrate.

[0303] Ex14. The aerosol-generating article according to example Ex13, in which the first aerosol-generating substrate has a lower aerosol former content than the second aerosol-generating substrate.

[0304] Ex15. The aerosol-generating article according to any preceding example, in which the first aerosolgenerating substrate has an aerosol-former content between 10 and 80 percent by weight on a dry weight basis, for example between 20 and 70 percent by weight on a dry weight basis and in which the second aerosol-generating substrate has an aerosol-former content of between 10 and 80 percent by weight on a dry weight basis, for example between 20 and 70 percent by weight on a dry weight basis. Ex16. The aerosol-generating article according to any preceding example, in which the first aerosolgenerating substrate has an aerosol-former content of at least 10 percent, for example at least 15 percent, for example at least 18 percent by weight on a dry weight basis.

[0305] Ex17. The aerosol-generating article according to any preceding example, in which the first aerosolgenerating substrate has an aerosol-former content of less than 30 percent, for example less than 25 percent, for example less than 20 percent by weight on a dry weight basis. Ex18. The aerosol-generating article according to any preceding example, in which the second aerosol-generating substrate has an aerosol-former content at least 40 percent, 45 percent, or 50 percent by weight on a dry weight basis.

[0306] Ex19. The aerosol-generating article according to any preceding example, in which the second aerosol-generating substrate has an aerosol-former content of less than 80 percent, 75 percent or 70 percent by weight on a dry weight basis.

[0307] Ex20. The aerosol-generating article according to any preceding example, in which the first aerosolgenerating substrate has a different bulk density to the second aerosol-generating substrate.

[0308] Ex21 . The aerosol-generating article according to example Ex20, in which the first aerosol-generating substrate has a lower bulk density than the second aerosol-generating substrate.

[0309] Ex22. The aerosol-generating article according to any preceding example, in which the first aerosolgenerating substrate has a bulk density of between 100 and 600 milligrams per cubic centimetre, for example between 200 and 500 milligrams per cubic centimetre, for example between 300 and 400 milligrams per cubic centimetre, and in which the second aerosol-generating substrate has a bulk density of between 100 and 600 milligrams per cubic centimetre, for example between 200 and 500 milligrams per cubic centimetre, for example between 300 and 400 milligrams per cubic centimetre.

[0310] Ex23. The aerosol-generating article according to any preceding example, in which the first aerosolgenerating substrate has a different mass to the second aerosol-generating substrate.

[0311] Ex24. The aerosol-generating article according to any preceding example, which the first aerosolgenerating substrate has a mass of between 80 milligrams and 500 milligrams, for example between 1 10 milligrams and 400 milligrams, for example between 200 milligrams and 300 milligrams

[0312] Ex25. The aerosol-generating article according to any preceding example, which the second aerosolgenerating substrate has a mass of between 80 milligrams and 500 milligrams, for example between 1 10 milligrams and 400 milligrams, for example between 200 milligrams and 300 milligrams.

[0313] Ex26. The aerosol-generating article according to any preceding example, in which at least one of the first aerosol-generating substrate and the second aerosol-generating substrate comprises a flavourant. Ex27. The aerosol-generating article according to any preceding claim, comprising a third cavity and a third aerosol-generating substrate positioned in the third cavity, in which the third cavity is located upstream of the second cavity.

[0314] Ex28. An aerosol-generating system comprising: an aerosol-generating article according to any preceding example; and an aerosol-generating device configured to engage with, and generate an aerosol from, the aerosol-generating article.

[0315] Ex29. The aerosol-generating system according to example Ex28, comprising a heater configured to heat at least one of the first aerosol-generating substrate and the second aerosol-generating substrate. Ex30. The aerosol-generating system according to example Ex29, in which the aerosol-generating device is configured to engage with the aerosol-generating article in a first position, in which the heater is aligned with, and configured to generate aerosol from, the first aerosol-forming substrate, and in a second position, in which the heater is aligned with, and configured to generate aerosol from, the second aerosol-forming substrate. Examples will now be further described with reference to the figures in which:

[0316] Figure 1 shows a perspective view of an aerosol-generating article according to the present disclosure;

[0317] Figure 2 shows an exploded perspective view of the aerosol-generating article of Figure 1 ;

[0318] Figure 3 shows an exploded perspective view of an aerosol-generating article according to the present disclosure;

[0319] Figure 4 shows a perspective view of an aerosol-generating article according to the present disclosure;

[0320] Figure 5 shows a perspective view of an aerosol-generating article according to the present disclosure;

[0321] Figure 6 shows an exploded perspective view of an aerosol-generating article according to the present disclosure;

[0322] Figure 7 shows a perspective view of an aerosol-generating article according to the present disclosure;

[0323] Figure 8 shows a perspective view of an aerosol-generating article according to the present disclosure;

[0324] Figure 9 shows an exploded perspective view of the aerosol-generating article of Figure 8;

[0325] Figure 10 shows an exploded perspective view of an aerosol-generating article according to the present disclosure;

[0326] Figure 1 1 shows an exploded perspective view of an aerosol-generating article according to the present disclosure;

[0327] Figure 12 shows an exploded perspective view of an aerosol-generating article according to the present disclosure;

[0328] Figure 13 shows an exploded perspective view of an aerosol-generating article according to the present disclosure;

[0329] Figure 14 shows an exploded perspective view of an aerosol-generating article according to the present disclosure;

[0330] Figure 15 shows an exploded perspective view of an aerosol-generating article according to the present disclosure;

[0331] Figure 16 shows an exploded perspective view of an aerosol-generating article according to the present disclosure;

[0332] Figure 17 shows an exploded perspective view of an aerosol-generating article according to the present disclosure;

[0333] Figure 18 shows a perspective view of an aerosol-generating article according to the present disclosure;

[0334] Figure 19 shows perspective view of an aerosol-generating article according to the present disclosure;

[0335] Figure 20 shows a plan view of the aerosol-generating article of Figure 19;

[0336] Figure 21 shows a schematic cross-sectional view of an aerosol-generating device according to the present disclosure; and Figure 22 shows a schematic cross-sectional view of the aerosol-generating device of Figure 21 in engagement with an aerosol-generating article of the present disclosure.

[0337] Figure 1 shows an aerosol-generating article 10 comprising a first planar external layer 24 forming a first planar external surface 21 , a second planar external layer 25 forming a second planar external surface 22, and a frame 50 positioned between the first planar external layer 24 and the second planar external layer 25. The first planar external layer 24 and the second planar external layer 25 both comprise an aerosol-generating substrate comprising an aerosol-generating material, namely tobacco. However, it will be understood that in some embodiments only one of the first planar external layer 24 and the second planar external layer 25 may comprise an aerosol-generating substrate. Alternatively, or additionally, the aerosol-generating substrate may be positioned elsewhere within the aerosolgenerating article 10.

[0338] The aerosol-generating article 10 has a length extending in the x-direction, a width extending in the y-direction and a thickness extending in the z-direction. The aerosol-generating article 10 has a length of 30 millimetres, a width of 10 millimetres, and a thickness of 3.1 millimetres.

[0339] The aerosol-generating article 10 is substantially flat aerosol-generating article or substantially planar aerosol-generating article. In particular, the thickness of the aerosol-generating article 10 is less than 50 percent of both the length and the width of the aerosol-generating article. The aerosolgenerating article 10 has a generally rectangular cuboid shape and a laminated structure formed by the first planar external layer 24, the frame 50 and the second planar external layer 25. The first planar external layer 24, the frame 50 and the second planar external layer 25 are bonded together with an adhesive, in particular guar gum, as discussed in more detail below in relation to Figure 2.

[0340] Figure 2 shows an exploded view of the aerosol-generating article 10 of Figure 1 .

[0341] The frame 50 has a length of 30 millimetres, a width of 10 millimetres, and a thickness of 2.7 millimetres. The frame 50 is made from cardboard and defines a frame aperture extending through the thickness of the frame 50. The frame aperture at least partially forms a cavity 30. The cavity 30 has length of 26 millimetres, a width of 6 millimetres, and a thickness of 2.7 millimetres. Therefore, the cavity 30 has a volume of about 421 .2 cubic millimetres. In this embodiment, the cavity 30 is substantially empty.

[0342] The frame 50 has a frame inner surface 52 extending in the z-direction or the transverse direction between the first planar external surface 21 and the second planar external surface 22. The frame inner surface 52 defines a cavity outer wall. The frame 50 has a frame outer surface 53 extending in the z-direction or the transverse direction between the first planar external surface 21 and the second planar external surface 22. The frame outer surface 53 at least partially defines one or more external surfaces of the aerosol-generating article, such as the front wall 13 and the back wall 14.

[0343] The frame 50 comprises a peripheral wall 51 that circumscribes the cavity 30. In more detail, the peripheral wall 51 is defined by the frame inner surface 52 and the frame outer surface 52. The peripheral wall 51 has a radial thickness, as measured between the frame inner surface 52 and the frame outer surface 53 in the x / y plane, of about 2 millimetres.

[0344] The first planar external layer 24 and the second planar external layer 25 have a thickness of 200 micrometres and are in physical contact with the frame 50. The first planar external layer 24 and the second planar external layer 25 are bonded to the frame with an adhesive 15. The first planar external layer 24 defines at least a portion of the cavity 30. The second planar external layer 25 defines at least a portion of the cavity 30.

[0345] The aerosol-generating article 10 comprises an air inlet 11 and an air outlet 12. The air inlet 11 and the air outlet 12 are defined by, and extend through, the peripheral wall 51 of the frame 50. The air inlet 11 and the air outlet 12 each have a rectangular cross-section, a width of 2 millimetres, and a thickness of 0.9 millimetres. An airflow passage extends between the air inlet 11 and the air outlet 12 through the cavity 30.

[0346] Figure 3 shows an exploded view of an aerosol-generating article 10 that is similar to the aerosol-generating article 10 of Figure 1 except that the first planar external layer 24 and the second planar external layer 25 do not comprise an aerosol-generating substrate. Instead, an aerosolgenerating substrate 40 is positioned within the cavity 30. The aerosol-generating substrate 40 comprises an aerosol-generating material in the form of tobacco cut filler and has an aerosol-former content of 5 percent by weight on a dry weight basis. As shown, the aerosol-generating substrate 40 fills the entire volume of the cavity 30. In the example of Figure 3, the aerosol-generating substrate 40 has a packing density of about 0.87, a density of about 0.3 grams per cubic centimetre, and a mass of about 110 milligrams. In another example, the aerosol-generating substrate 40 may have a different packing density, a different density and a different mass. For example, aerosol-generating substrate may have a packing density of 0.64, a density of 0.35 grams per cubic centimetre, and a mass of about 95 milligrams.

[0347] Figure 4 shows an aerosol-generating article 10 similar to the aerosol-generating article 10 of Figures 1 and 3 except that the aerosol-generating article 10 of Figure 4 comprises an outer wrapper 23 defining the first planar external surface 21 and the second planar external surface 22 instead of the first planar external layer 24 and the second planar external layer 25.

[0348] Figure 5 shows an aerosol-generating article 10 similar to the aerosol-generating article 10 of Figure 1 except that the aerosol-generating article 10 of Figure 5 further comprises a first aerosolgenerating substrate layer 41 and a second aerosol-generating substrate layer 42. The first aerosolgenerating substrate layer 41 and the second aerosol-generating substrate layer 42 are formed from a sheet of aerosol-generating material. In particular, a sheet of homogenised tobacco material having an aerosol-former content of 5 percent by weight on a dry weight basis. The first aerosol-generating substrate layer 41 and the second aerosol-generating substrate layer 42 each have a length equal to the length of the aerosol-generating article 10, a width equal to the width of the aerosol-generating article 10 and a thickness of 200 micrometres. That is, the aerosol-generating article 10 has a length of 30 millimetres, a width of 10 millimetres, and a thickness of 3.5 millimetres.

[0349] The first aerosol-generating substrate layer 41 and the second aerosol-generating substrate layer 42 are in physical contact with the frame 50 and are bonded to the frame with an adhesive 15. The first aerosol-generating substrate layer 41 defines at least a portion of the cavity 30. The second aerosol-generating layer 42 defines at least a portion of the cavity 30.

[0350] The first planar external layer 24 is in physical contact with the first aerosol-generating substrate layer 41 and are bonded together with an adhesive 15. The second planar external layer 25 is in physical contact with the second aerosol-generating substrate layer 42 and are bonded together with an adhesive 15.

[0351] Figure 6 shows an exploded view of an aerosol-generating article 10 that is similar to the aerosol-generating article 10 of Figure 5 except that an aerosol-generating substrate 40 is positioned within the cavity 30 as described in relation to Figure 3. The aerosol-generating substrate 40 comprises an aerosol-generating material in the form of tobacco cut filler and has an aerosol-former content of 5 percent by weight on a dry weight basis. As shown, the aerosol-generating substrate 40 fills the entire volume of the cavity 30.

[0352] Figure 7 shows an aerosol-generating article 10 similar to the aerosol-generating article 10 of Figure 5 except that the aerosol-generating article 10 of Figure 7 comprises an outer wrapper 23 defining the first planar external surface 21 and the second planar external surface 22 instead of the first planar external layer 24 and the second planar external layer 25.

[0353] Figure 8 shows an aerosol-generating article 110 that is similar to the aerosol-generating article 10 of Figure 1 except that the aerosol-generating article 110 of Figure 8 comprises a first cavity 33 and a second cavity 34. The features of the aerosol-generating article 110 that are the same as the features of the aerosol-generating article 10 are denoted with the same reference numerals.

[0354] Figure 9 shows an exploded view of the aerosol-generating article 110 of Figure 8. In Figure 9, the first cavity 33 is substantially empty and the second cavity 34 is substantially empty. The second cavity 34 is located upstream of the first cavity 33.

[0355] The first cavity 33 has length of 12 millimetres, a width of 6 millimetres, and a thickness of 2.7 millimetres. The second cavity 34 has length of 12 millimetres, a width of 6 millimetres, and a thickness of 2.7 millimetres.

[0356] The frame 50 defines a first frame aperture extending through the thickness of the frame 50 and the first frame aperture at least partially forms the first cavity 33. The frame 50 defines a second frame aperture extending through the thickness of the frame 50 and the second frame aperture at least partially forms the second cavity 34.

[0357] The frame 50 comprises dividing wall 57 which separates the first cavity 33 and the second cavity 34. The dividing wall 57 defines an aperture extending from the first cavity 33 to the second cavity 34. The aperture of the dividing wall 57 defines at least a portion of the airflow passage between the air inlet 11 and the air outlet 12.

[0358] The first planar external layer 24 overlies an end of the first cavity 33 and the second planar external layer 25 overlies an opposite end of the first cavity 33. That is, the frame 50, the first planar external layer 24 and the second planar external layer 25 collectively define the first cavity 33. The first planar external layer 24 overlies an end of the second cavity 34 and the second planar external layer 25 overlies an opposite end of the second cavity 34. That is, the frame 50, the first planar external layer 24 and the second planar external layer 25 collectively define the second cavity 34.

[0359] Figure 10 shows an exploded view of an aerosol-generating article 110 that is similar to the aerosol-generating article 110 of Figures 8 and 9 except that a first aerosol-generating substrate 45 is positioned within the first cavity 33 and a second aerosol-generating substrate 46 is positioned within the second cavity 34. The first aerosol-generating substrate 45 comprises an aerosol-generating material in the form of tobacco cut filler and comprises 15 percent by weight on a dry weight basis of an aerosol-former, in this case glycerol. The first aerosol-generating substrate 45 fills the entire volume of the first cavity 33. The first aerosol-forming substrate has a mass of 100 milligrams. The bulk density of the first aerosolgenerating substrate is about 500 mg per cubic centimetre. The second aerosol-generating substrate 46 comprises an aerosol-generating material in the form of cast-leaf tobacco and comprises 50 percent by weight on a dry weight basis of an aerosol-former, in this case glycerol. The second aerosolgenerating substrate 46 fills the entire volume of the second cavity 34. The second aerosol-forming substrate has a mass of 100 milligrams. The bulk density of the second aerosol-generating substrate is about 500 mg per cubic centimetre.

[0360] Figure 11 shows an exploded view of an aerosol-generating article 210 that is similar to the aerosol-generating article 110 of Figure 10 except that the first aerosol generating substrate 245 is in the form of a plug of aerosol-generating material. The second aerosol-generating substrate 246 is in the form of a plug of aerosol-generating material. The plugs substantially fill the first and second cavities. The features of the aerosol-generating article 210 that are the same as the features of the aerosol-generating article 110 are denoted with the same reference numerals.

[0361] Figure 12 shows an exploded view of an aerosol-generating article 310 that is similar to the aerosol-generating article 210 of Figure 11 except that the first cavity 333 is a different size to the second cavity 334. The features of the aerosol-generating article 310 that are the same as the features of the aerosol-generating article 210 are denoted with the same reference numerals. In this embodiment, the second cavity 334 has a greater volume than the first cavity 333. However, it will be appreciated that in other embodiments, the first cavity can have a greater volume than the second cavity. The first cavity

[0362] 333 has length of 8 millimetres, a width of 6 millimetres, and a thickness of 2.7 millimetres. The second cavity 334 has length of 16 millimetres, a width of 6 millimetres, and a thickness of 2.7 millimetres. Therefore, the first cavity 333 has a volume of approximately 130 cubic millimetre and the second cavity

[0363] 334 has a volume of approximately 260 cubic millimetres.

[0364] The first aerosol-generating substrate 345 is in the form of a plug of aerosol-generating substrate comprising a flavourant, for example menthol. The first aerosol-generating substrate 345 has a volume that is about 85 to 95 percent of the volume of the first cavity.

[0365] The second aerosol-generating substrate 346 is in the form of a plug of aerosol-generating material. The second aerosol-generating substrate 346 comprises a plug of an aerosol-generating material in the form of cast-leaf tobacco and comprises 50 percent by weight on a dry weight basis of an aerosol-former, in this case glycerol. The second aerosol-generating substrate 346 a volume that is about 85 to 95 percent of the volume of the second cavity.

[0366] The first aerosol-generating substrate 345 is positioned immediately upstream of the air outlet 12.

[0367] Figure 13 shows an exploded view of an aerosol-generating article 410 that is similar to the aerosol-generating article 110 of Figure 10. The features of the aerosol-generating article 410 that are the same as the features of the aerosol-generating article 110 are denoted with the same reference numerals. A filter element 60 is positioned within the air outlet 12. The filter element 60 is made from cellulose acetate and has the same dimensions as the air outlet 12.

[0368] The first aerosol-generating substrate 45 is positioned in the first cavity 33. The first aerosolgenerating substrate 45 is identical to the first aerosol-generating substrate described in relation to Figure 10.

[0369] The second aerosol-generating substrate 446 is positioned in the second cavity 34. The second aerosol-generating substrate 446 has one of the compositions (Examples A, B, C, D and E) shown in Table 1 .

[0370] Figure 14 shows an exploded perspective view of an aerosol-generating article 510 that is similar to the aerosol-generating article 110 of Figure 10 except that the second aerosol-generating substrate 546 is in the form of a sheet of aerosol-generating material, in particular a corrugated sheet of homogenised tobacco material. The features of the aerosol-generating article 510 that are the same as the features of the aerosol-generating article 110 are denoted with the same reference numerals.

[0371] The first cavity aerosol-generating substrate 45 is identical to the first cavity aerosol-generating substrate 45 described in relation to Figure 10.

[0372] The corrugated sheet of homogenised tobacco material in the second cavity comprises a plurality of parallel corrugations having a plurality of substantially parallel peaks and troughs. The plurality of parallel corrugations are defined by a corrugation profile which, is sinusoidal. The plurality of parallel corrugations have a corrugation wavelength of about 0.92 millimetres. The corrugation amplitude is approximately the same as the thickness of the cavity.

[0373] The plurality of parallel corrugations form a plurality of channels between the sheet of aerosolgenerating material and the first planar external layer 24, and a plurality of channels between the sheet of aerosol-generating material and the second planar external layer 25. The plurality of channels extend in a longitudinal direction of the aerosol-generating article 510 and form at least a portion of the airflow passage extending between the air inlet 11 and the air outlet 12.

[0374] Figure 15 shows an exploded view of an aerosol-generating article 610 similar to the aerosolgenerating article 110 of Figure 11 except that the aerosol-generating article 610 comprises a first cavity 633, a second cavity 634 and a third cavity 635. The second cavity 634 is located upstream of the first cavity 633. The third cavity 635 is located upstream of the first cavity 633 and the second cavity 634.

[0375] The first cavity 633 has length of 6 millimetres, a width of 6 millimetres, and a thickness of 2.7 millimetres. The second cavity 634 has length of 6 millimetres, a width of 6 millimetres, and a thickness of 2.7 millimetres. The third cavity 635 has length of 6 millimetres, a width of 6 millimetres, and a thickness of 2.7 millimetres. It should be appreciated that in other embodiments, the first, second and third cavities may have different dimensions.

[0376] The frame 50 defines a frame first aperture extending through the thickness of the frame 50 and the frame first aperture at least partially forms the first cavity 633. The frame 50 defines a second frame aperture extending through the thickness of the frame 50 and the second frame aperture at least partially forms the second cavity 34. The frame 50 defines a third frame aperture extending through the thickness of the frame 50 and the third frame aperture at least partially forms the third cavity 634.

[0377] The frame 50 comprises a first dividing wall 657 which separates the first cavity 633 and the second cavity 634. The first dividing wall 657 defines an aperture extending from the first cavity 633 to the second cavity 634. The aperture of the dividing wall 657 defines at least a portion of the airflow passage between the air inlet 11 and the air outlet 12.

[0378] The frame 50 comprises a second dividing wall 658 which separates the second cavity 634 and the third cavity 635. The second dividing wall 658 defines an aperture extending from the second cavity 634 to the third cavity 635. The aperture of the dividing wall 658 defines at least a portion of the airflow passage between the air inlet 11 and the air outlet 12.

[0379] The first planar external layer 24 overlies an end of the first cavity 633 and the second planar external layer 25 overlies an opposite end of the first cavity 633. That is, the frame 50, the first planar external layer 24 and the second planar external layer 25 collectively define the first cavity 633. The first planar external layer 24 overlies an end of the second cavity 634 and the second planar external layer 25 overlies an opposite end of the second cavity 634. That is, the frame 50, the first planar external layer 24 and the second planar external layer 25 collectively define the second cavity 634. The first planar external layer 24 overlies an end of the third cavity 635 and the second planar external layer 25 overlies an opposite end of the third cavity 635. That is, the frame 50, the first planar external layer 24 and the second planar external layer 25 collectively define the third cavity 635.

[0380] A first aerosol-generating substrate 645 is positioned within the first cavity 633, a second aerosol-generating substrate 646 is positioned within the second cavity 634, and a third aerosolgenerating substrate 647 is positioned within the third cavity 635. The first aerosol-generating substrate 645, the second aerosol-generating substrate 646, and the third aerosol-generating substrate 647 are each in the form of a plug of aerosol-generating material. The plugs substantially fill the first, second and third cavities.

[0381] The first aerosol-generating substrate 645 comprises an aerosol-generating material in the form of tobacco cut filler and comprises 15 percent by weight on a dry weight basis of an aerosol-former, in this case glycerol. The first aerosol-generating substrate 45 substantially fills the volume of the first cavity 633. The first aerosol-forming substrate has a mass of 50 milligrams. The bulk density of the first aerosol-generating substrate is about 500 mg per cubic centimetre. The second aerosol-generating substrate 646 comprises an aerosol-generating material in the form of cast-leaf tobacco and comprises 50 percent by weight on a dry weight basis of an aerosol-former, in this case glycerol. The second aerosol-generating substrate 646 substantially fills the volume of the second cavity 634. The second aerosol-forming substrate has a mass of 50 milligrams. The bulk density of the second aerosolgenerating substrate is about 500 mg per cubic centimetre. The third aerosol-generating substrate 47 comprises an aerosol-generating material in the form of tobacco cut filler and comprises 15 percent by weight on a dry weight basis of an aerosol-former, in this case glycerol. The third aerosol-generating substrate 647 substantially fills the volume of the third cavity 635. The first aerosol-forming substrate has a mass of 50 milligrams. The bulk density of the first aerosol-generating substrate is about 500 mg per cubic centimetre. In this embodiment, the first aerosol-generating substrate 645 is substantially identical to the third aerosol-generating substrate 647, so that the same aerosol may be produced, regardless of the direction of insertion of the aerosol-generating article 910 into an aerosol-generating device to generate an aerosol. In other words, the same aerosol may be generated irrespectively of whether the first aerosol-generating substrate 645 is located upstream of the second aerosol-generating substrate 646, or if the second aerosol-generating substrate 647 is located upstream of the second aerosol-generating substrate 646. However, it will be appreciated that other embodiments, the first aerosol-generating substrate 645 may be different to the third aerosol-generating substrate 647, for example the first aerosol-generating substrate and the second aerosol-generating substrate may have a different mass, volume, bulk density, aerosol former or aerosol former content, in which case a different aerosol may be experienced depending on the direction of insertion of the aerosol-generating article into an aerosol-generating device.

[0382] Figure 16 shows an exploded view of an aerosol-generating article 110 that is similar to the aerosol-generating article 110 of Figure 9 except that the aerosol-generating article 10 further comprises a first aerosol-generating substrate layer 41 and a second aerosol-generating substrate layer 42 as described in relation to Figure 5.

[0383] The first aerosol-generating substrate layer 41 and the second aerosol-generating substrate layer 42 are in physical contact with the frame 50 and are bonded to the frame with an adhesive 15. The first aerosol-generating substrate layer 41 overlies an end of the first cavity 33 and the second aerosol-generating substrate layer 42 overlies an opposite end of the first cavity 33. That is, the frame 50, the first aerosol-generating substrate layer 41 and the second aerosol generating substrate layer 42 collectively define the first cavity 33. The first aerosol-generating substrate layer 41 overlies an end of the second cavity 34 and the second aerosol-generating substrate layer 42 overlies an opposite end of the second cavity 34. That is, the frame 50, the first aerosol-generating substrate layer 41 and the second aerosol-generating substrate layer 42 collectively define the second cavity 34.

[0384] Figure 17 shows an exploded view of an aerosol-generating article 110 similar to the aerosolgenerating article 110 of Figure 16 except that a first cavity aerosol-generating substrate 45 is positioned within the first cavity 33 and a second cavity aerosol-generating substrate 46 is positioned within the second cavity 34.

[0385] The first aerosol-generating substrate 45 comprises an aerosol-generating material in the form of tobacco cut filler and comprises 15 percent by weight on a dry weight basis of an aerosol-former, in this case glycerol. The first cavity aerosol-generating substrate 45 fills the entire volume of the first cavity 33. The first aerosol-forming substrate has a mass of 60 milligrams. The bulk density of the first aerosol-generating substrate is about 300 mg per cubic centimetre. The second aerosol-generating substrate 46 comprises an aerosol-generating material in the form of cast-leaf tobacco and comprises 50 percent by weight on a dry weight basis of an aerosol-former, in this case glycerol. The second aerosol-generating substrate 46 fills the entire volume of the second cavity 34. The second aerosolforming substrate has a mass of 60 milligrams. The bulk density of the second aerosol-generating substrate is about 300 mg per cubic centimetre.

[0386] Figure 18 shows an aerosol-generating article 710 similar to the aerosol-generating article 10 of Figures 16 and 17 except that the aerosol-generating article 710 of Figure 18 comprises an outer wrapper 23 defining the first planar external surface 21 and the second planar external surface 22 instead of the first planar external layer 24 and the second planar external layer 25. The features of the aerosol-generating article 710 that are the same as the features of the aerosol-generating article 10 are denoted with the same reference numerals.

[0387] Figure 19 shows perspective view of an aerosol-generating article 810 according to the present disclosure. The aerosol-generating article 810 is similar to the aerosol-generating of any of Figure 8 to 15, except that the aerosol-generating article 810 of Figure 19 comprises depressions configured to engage with an aerosol-generating device. The aerosol-generating article 810 comprises a first depression 51 and a second depression 52. The first and second depressions 51 , 52 are configured to engage with corresponding first and second protrusions of an aerosol-generating device.

[0388] Figure 20 shows a plan view of the aerosol-generating article of Figure 19.

[0389] In use, the aerosol-generating article 810 is inserted into an aerosol-generating device for generating an aerosol. The aerosol-generating article 810 with the air inlet end first. The aerosolgenerating article 810 may be inserted until the second depression 52 is aligned with and engaged with a corresponding first protrusion of the aerosol-generating device. In this position the second cavity and the second aerosol-generating substrate are aligned with a heater of the aerosol-generating device, which is configured to heat the second aerosol-generating substrate. After usage of the aerosolgenerating article 810 and aerosol-generating device in this position, in which the second aerosolgenerating substrate generates an aerosol. The aerosol-generating article 810 may be inserted further into the aerosol-generating device until the first depression 51 is aligned with and engaged with the first protrusion of the aerosol-generating device. Preferably, the second depression 52 is aligned with and engaged with a second protrusion of the aerosol-generating device. In this position, the first cavity and the first aerosol-generating substrate are aligned with a heater of the aerosol-generating device, which is configured to heat the first aerosol-generating substrate to generate an aerosol.

[0390] Figure 21 shows a schematic cross-sectional view of an aerosol-generating device 90 configured for use with an aerosol-generating article, for example any of aerosol generating articles 10, 110, 210, 310, 410, 510, 610, 710, or 810, described herein. The aerosol-generating device 90 is an elongate aerosol-generating device extending between a proximal end 91 and a distal end 92. The aerosol-generating device 90 comprises a battery 93, a controller 94, a first heater 95 and a second heater 96 located within a housing 97. The controller 94 controls supply of power from the battery 93 to the first heater 95 and the second heater 96. A cavity 1000 is defined in the device 90, the cavity 1000 having an opening 1010 defined in the proximal end 91 of the device 90. The opening 1010 is rectangular in shape and is dimensioned to accommodate the transverse cross-section of the aerosolgenerating article 10. The cavity 1000 comprises an upper planar surface 1020 and a lower planar surface 1030. The first heater 95 is located in the upper planar surface 1020 to heat the first planar external surface 21 of an aerosol-generating article 10 inserted into the cavity 1000, and the second heater 96 is located in the lower planar surface 1030 to heat the second planar external surface 22 of an aerosol-generating article 10 inserted into the cavity 1000. The device 90 comprises an air inlet 98 defining an air-flow path configured to allow air to flow into the cavity 1000 from outside the device.

[0391] Figure 22 shows a schematic cross-sectional view of the aerosol-generating device 90 of Figure 21 in engagement with the aerosol-generating article 110 of Figure 10. However, it will be appreciated that the device may engage with any of the aerosol-generating articles as described herein. There is little tolerance between the first planar external surface 21 and the second planar external surface 22 of the aerosol-generating article 110 and the internal surfaces 1020, 1030 of the cavity 1000. Thus, there is a snug fit between the aerosol-generating article 110 and the aerosol-generating device 90. When a consumer has inserted the aerosol-generating article 110 into the cavity 1000, the device can be operated. The first heater 95 heats the first planar external surface 21 of the aerosol-generating article 110 and the second heater 96 heats the second planar external surface 22 of the aerosolgenerating article, and as a result the first aerosol-generating substrate and second aerosol-generaing substrate are heated. Volatile components of the first aerosol-generating substrate are evaporated and condense in the first cavity 33 of the aerosol-generating article 110 to form an aerosol. Volatile components of the second aerosol-generating substrate are evaporated and condense in the second cavity 34 of the aerosol-generating article 110 to form an aerosol. The consumer inhales the aerosol from the first cavity and second cavity by drawing on the end of the aerosol-generating article 110 comprising the air outlet 12. Once the aerosol-generating substrate has been depleted of volatile components, the aerosol-generating article 110 is removed from the cavity 1000 and disposed of.

[0392] For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 10% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

Claims1 . An aerosol-generating article for use with an aerosol-generating device to generate an aerosol, the aerosol-generating article comprising: a first cavity and a second cavity, in which the second cavity is located in series with the first cavity; a first aerosol-generating substrate positioned in the first cavity; a second aerosol-generating substrate different to the first aerosol-forming substrate and positioned in the second cavity; an air inlet, an air outlet, and an airflow passage extending between the air inlet and the air outlet through the first cavity and the second cavity; a first planar external surface and a second planar external surface; and a frame positioned between the first planar external surface and the second planar external surface, wherein the frame at least partially defines the first cavity and the second cavity.

2. The aerosol-generating article according to claim 1 , in which the first cavity has a different volume to the second cavity.

3. The aerosol-generating article according to claim 1 or 2, in which the volume of the first cavity is greater than 100 cubic millimetres, for example greater than 200 cubic millimetres, for example greater than 300 cubic millimetres, and in which the volume of the second cavity is greater than 100 cubic millimetres, for example greater than 200 cubic millimetres, for example greater than 300 cubic millimetres.

4. The aerosol-generating article according to any preceding claim, in which the first cavity has a different length to the second cavity.

5. The aerosol-generating article according to any preceding claim, in which the first aerosolgenerating substrate has a lower aerosol former content than the second aerosol-generating substrate.

6. The aerosol-generating article according to any preceding claim, in which the first aerosolgenerating substrate has an aerosol-former content between 10 and 80 percent by weight on a dry weight basis, for example between 20 and 70 percent by weight on a dry weight basis and in which the second aerosol-generating substrate has an aerosol-former content of between 10 and 80 percent by weight on a dry weight basis, for example between 20 and 70 percent by weight on a dry weight basis.

7. The aerosol-generating article according to any preceding claim, in which the first aerosolgenerating substrate has a lower bulk density than the second aerosol-generating substrate.

8. The aerosol-generating article according to any preceding claim, in which the first aerosolgenerating substrate has a bulk density of between 100 and 600 milligrams per cubic centimetre, for example between 200 and 500 milligrams per cubic centimetre, for example between 300 and 400 milligrams per cubic centimetre, and in which the second aerosol-generating substrate has a bulk density of between 100 and 600 milligrams per cubic centimetre, for example between 200 and 500 milligrams per cubic centimetre, for example between 300 and 400 milligrams per cubic centimetre.

9. The aerosol-generating article according to any preceding claim, in which the first aerosolgenerating substrate has a different mass to the second aerosol-generating substrate.

10. The aerosol-generating article according to any preceding claim, in which the first aerosolgenerating substrate has a mass of between 80 milligrams and 500 milligrams, for example between 1 10 milligrams and 400 milligrams, for example between 200 milligrams and 300 milligrams, and in which the second aerosol-generating substrate has a mass of between 80 milligrams and 500 milligrams, for example between 1 10 milligrams and 400 milligrams, for example between 200 milligrams and 300 milligrams.1 1 . The aerosol-generating article according to any preceding claim, in which at least one of the first aerosol-generating substrate and the second aerosol-generating substrate comprises a flavourant.

12. The aerosol-generating article according to any preceding claim, in which the frame comprises a dividing wall which separates the first cavity and the second cavity, in which the dividing wall defines or forms an aperture, and in which the aperture defines or forms a portion of the airflow passage between the air inlet and the air outlet.

13. The aerosol-generating article according to any preceding claim comprising a third cavity and a third aerosol-generating substrate positioned in the third cavity, in which the third cavity is located in series with the second cavity.

14. An aerosol-generating system comprising: an aerosol-generating article according to any preceding claim; and an aerosol-generating device configured to engage with, and generate an aerosol from, the aerosol-generating article.

15. The aerosol-generating system according to claim 14, comprising a heater configured to heat at least one of the first aerosol-generating substrate and the second aerosol-generating substrate, wherein the aerosol-generating device is configured to engage with the aerosol-generating article in a first position, in which the heater is aligned with, and configured to generate aerosol from, the first aerosol-forming substrate, and in a second position, in which the heater is aligned with, and configured to generate aerosol from, the second aerosol-forming substrate.

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