Aerosol-generating article comprising capsule and susceptor

Abstract

There is provided an aerosol-generating article (10) for generating an inhalable aerosol upon heating, the aerosol-generating article (10) comprising a bladder (14; 414) for a motor vehicle. The bladder (14; 414) includes a bladder outer wall (20) defining a lumen (22) and a plurality of first particles (24) within the lumen (22). Each of the first particles (24) comprises an aerosol-forming substrate. The bladder (14; 414) further comprises only one of the following: a plurality of second particles (25; 225; 225; 325), the second particles (25; 225; 225; 325) comprises a susceptor material and does not comprise an aerosol-forming substrate; or a single susceptor element (425) within the lumen (22). There is also provided an aerosol-generating system (100) comprising an aerosol-generating article (10), and forming a capsule (14; 14 ') for an aerosol-generating article (10). 414) of the method.

Description

Field of the Invention

[0001] The present invention relates to an aerosol-generating article comprising a capsule, the capsule comprising a plurality of first particles of an aerosol-forming substrate and a susceptor. The present invention also relates to an aerosol-generating system comprising the aerosol-generating article, and a method of forming a capsule. Background Art

[0002] Aerosol-generating articles in which an aerosol-forming substrate, such as a tobacco-containing substrate, is heated rather than burned are known in the art. Generally, in such heat-not-burn smoking articles, an aerosol is generated by transferring heat from a heat source to a physically separated aerosol-forming substrate or material, which may be positioned in contact with, inside, around or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-forming substrate by heat transfer from the heat source and entrained in the air drawn through the aerosol-generating article. When the released compounds cool, the compounds condense to form an aerosol.

[0003] Many prior art documents disclose aerosol-generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosol-generating devices, in which an aerosol is generated by transferring heat from one or more electrical heater elements of the aerosol-generating device to the aerosol-forming substrate of a heat-not-burn aerosol-generating article. For example, electrically heated aerosol-generating devices comprising resistive heating elements have been proposed, in which the resistive heating elements generate heat for heating the aerosol-forming substrate. Other electrically heated aerosol-generating devices comprising induction heating systems have been proposed, in which an inductor coil generates a changing magnetic field for heating a susceptor element, the susceptor element being arranged to heat the aerosol-forming substrate. For example, an inductively heatable aerosol-generating article has been proposed in WO 2015 / 176898A1, which comprises an aerosol-forming substrate and a susceptor arranged within the aerosol-forming substrate.

[0004] Certain types of aerosol - forming substrates containing nicotine and a relatively high content of aerosol - forming agents are known, for example, gels and membranes containing nicotine. Such substrates are generally very stable during storage and advantageously provide a very consistent nicotine delivery to the consumer upon heating. They can also advantageously generate an aerosol at a lower temperature than other solid substrates. However, the use of this type of aerosol - forming substrate can also pose problems. The relatively high content of aerosol - forming agents increases the risk of leakage of the aerosol - forming agent from the substrate during storage and during use. Additionally, some substrates such as gel compositions typically melt when heating the aerosol - forming substrate within an aerosol - generating device during use. As a result, the viscosity of the gel composition significantly increases, and it may be more difficult to control the movement of the gel composition and, in particular, more difficult to keep it within the aerosol - generating article. Leakage of the aerosol - forming agent or the melted gel composition from the aerosol - generating article is undesirable because it may leak into the heating chamber of the aerosol - generating device and potentially contaminate the aerosol - generating device. Leakage of the aerosol - forming agent or the gel composition may also be unpleasant for the consumer.

[0005] Furthermore, even solid aerosol - forming substrates can include one or more volatile compounds, such as one or more aerosol - forming agents, which can escape from the aerosol - generating article over time if the aerosol - generating article is not stored correctly.

[0006] Accordingly, it is desirable to provide a novel aerosol - generating article having an arrangement that provides improved retention of the aerosol - forming substrate and volatile compounds within the aerosol - generating article during storage and use. It is also desirable to provide such an aerosol - generating article that enables efficient heating of the aerosol - forming substrate such that an aerosol can be generated from the aerosol - forming substrate in an efficient and consistent manner. Summary of the Invention

[0007] The present disclosure relates to an aerosol - generating article for generating an inhalable aerosol upon heating. The aerosol - generating article can include a capsule. The capsule can include a capsule outer wall defining an inner cavity. The capsule can include a plurality of first particles within the inner cavity. Each of the first particles can include an aerosol - forming substrate. The capsule can also include a single sensor element within the inner cavity. The capsule can further include a plurality of second particles within the inner cavity. Each of the second particles can include a sensor material and does not include an aerosol - forming substrate.

[0008] According to the present invention, there is provided an aerosol-generating article for generating an inhalable aerosol upon heating, the aerosol-generating article comprising a capsule. The capsule comprises a capsule outer wall defining an inner cavity and a plurality of first particles within the inner cavity. Each of the first particles comprises an aerosol-forming substrate. The capsule further comprises only one of: a plurality of second particles within the inner cavity, each of the second particles comprising a sensor material and not comprising an aerosol-forming substrate; or a single sensor element within the inner cavity.

[0009] As used herein, the term "aerosol-generating article" refers to an article comprising an aerosol-forming substrate that is heated to produce and deliver an inhalable aerosol to a consumer. As used herein, the term "aerosol-forming substrate" denotes a substrate capable of releasing volatile compounds upon heating to generate an aerosol.

[0010] As used herein, the term "aerosol-generating device" refers to a device comprising a heater element that interacts with the aerosol-forming substrate of an aerosol-generating article to generate an aerosol.

[0011] As used herein, the term "longitudinal" refers to the direction corresponding to the main longitudinal axis of the aerosol-generating article, which extends between the upstream end and the downstream end of the aerosol-generating article. As used herein, the terms "upstream" and "downstream" describe the relative positions of elements or portions of elements of the aerosol-generating article with respect to the direction in which the aerosol is delivered through the aerosol-generating article during use.

[0012] During use, air is drawn through the aerosol-generating article in the longitudinal direction. The term "transverse" refers to the direction perpendicular to the longitudinal axis.

[0013] The term "length" denotes the dimension of a component of the aerosol-generating article in the longitudinal direction. For example, it can be used to denote the dimension of a hollow tubular element or a capsule in the longitudinal direction.

[0014] As used herein, the term "solid" refers to an aerosol-forming substrate that is not a liquid or a gas and does not flow such that it retains its shape and form at room temperature. In the context of the present invention, the term "solid" encompasses gel materials and compositions.

[0015] As used herein, the terms "sensor", "sensor element" and "sensor material" refer to materials capable of being inductively heated. That is, the sensor material is capable of absorbing electromagnetic energy and converting it into heat.

[0016] Advantageously, providing particles of the receptor material or individual receptor elements in the lumen of the capsule provides direct contact between the receptor and the particles of the aerosol-forming substrate. Advantageously, the direct contact between the receptor and the aerosol-forming substrate provides efficient heating of the aerosol-forming substrate. Advantageously, the direct contact between the receptor and the aerosol-forming substrate facilitates rapid heating of the aerosol-forming substrate at the start of the heating cycle. Advantageously, the rapid heating of the aerosol-forming substrate facilitates rapid delivery of the aerosol to the user.

[0017] Advantageously, providing the aerosol-forming substrate as a plurality of first particles that are different from the receptor material or individual receptor elements can simplify the manufacture of the aerosol-generating article. For example, it may be easier to manufacture the first particles of the aerosol-forming substrate separately from the individual receptor elements or the plurality of second particles of the receptor material.

[0018] Advantageously, positioning the first particles of the aerosol-forming substrate together with the individual receptor elements or the plurality of second particles of the receptor material in the lumen of the capsule can facilitate the uniform distribution of the aerosol-forming substrate relative to the receptor. Advantageously, the uniform distribution of the aerosol-forming substrate relative to the receptor can facilitate the uniform heating of the aerosol-forming substrate and thus facilitate consistent aerosol delivery throughout the heating cycle. Advantageously, the uniform distribution of the aerosol-forming substrate relative to the receptor can facilitate the uniform heating of the aerosol-forming substrate such that the aerosol generation profile of the aerosol-generating article is independent of the orientation of the capsule in the aerosol-generating article and independent of the orientation of the aerosol-generating article in the aerosol-generating device.

[0019] Advantageously, providing the receptor as part of the aerosol-generating article allows the heater to be replaced each time the aerosol-generating article is replaced. Advantageously, this eliminates the heater contamination problem inherent in aerosol-generating devices that include a resistive heater that is repeatedly used to heat a plurality of aerosol-generating articles.

[0020] The capsule may include a plurality of second particles. Preferably, the plurality of second particles are mixed with the plurality of first particles. Advantageously, mixing the second particles with the first particles can facilitate the uniform distribution of the aerosol-forming substrate relative to the receptor material. Advantageously, this can facilitate the efficient transfer of heat from the receptor material to the aerosol-forming substrate.

[0021] The plurality of first particles can have any suitable form. The plurality of first particles can include a plurality of beads, pellets, microparticles, strips, fragments or flakes.

[0022] The plurality of second particles can have any suitable form. The plurality of second particles can include a plurality of beads, pellets, microparticles, strips, fragments or flakes.

[0023] Each of the first particles in the first particle may have an outer surface including a first shape. Each of the second particles in the second particle may have an outer surface including a second shape.

[0024] The first shape and the second shape may be the same.

[0025] The second shape may be different from the first shape. A part of the second shape may be configured to engage with a part of the first shape. In other words, a part of the second shape may be complementary to a part of the first shape. A part of the second shape may be configured to receive a part of the first shape. A part of the second shape may be configured to be received in a part of the first shape. In other words, a part of the first shape may be configured to receive a part of the second shape.

[0026] Advantageously, providing a first shape and a second shape configured to engage with each other may increase or maximize the contact between the first particle and the second particle. Advantageously, increasing or maximizing the contact between the first particle and the second particle may facilitate the effective transfer of heat from the sensor material to the aerosol-forming substrate.

[0027] Preferably, the first shape is configured to reduce or prevent the engagement between the first particles. In other words, preferably, the first shape is configured such that it cannot engage with itself or receive a part of itself. Advantageously, this may facilitate the mixing of the first particle and the second particle.

[0028] Preferably, the second shape is configured to reduce or prevent the engagement between the second particles. In other words, preferably, the second shape is configured such that it cannot engage with itself or receive a part of itself. Advantageously, this may facilitate the mixing of the first particle and the second particle.

[0029] Preferably, each of the second particles in the second particle has at least one of a size and a shape that reduces or minimizes the interlocking of the second particles with each other. Advantageously, reducing or minimizing the interlocking of the second particles with each other may facilitate the mixing of the second particle and the first particle.

[0030] Preferably, each of the second particles in the second particle has at least one of a size and a shape that increases or maximizes the contact between the second particle and the first particle. Advantageously, increasing or maximizing the contact between the second particle and the first particle may facilitate the transfer of heat from the sensor material to the aerosol-forming substrate.

[0031] The first shape may be a convex shape. The first shape may be a sphere, an ellipsoid or an oval. The first shape may be a polyhedral shape. The first shape may be a star polyhedral shape.

[0032] The second shape may be a convex shape. The second shape may be a sphere, an ellipsoid, or an ovoid. The second shape may be a polyhedral shape. The second shape may be a star polyhedral shape.

[0033] Each of the first shape and the second shape may be a sphere, an ellipsoid, or an ovoid. Advantageously, providing a spherical shape, an ellipsoid shape, or an ovoid shape for each of the first particles and the second particles may simplify the manufacture of the first particles and the second particles. Advantageously, providing a spherical shape, an ellipsoid shape, or an ovoid shape for each of the first particles and the second particles may facilitate the mixing of the second particles with the first particles.

[0034] The first shape may be a sphere, an ellipsoid, or an ovoid, and the second shape may be a star polyhedral shape. Advantageously, providing a spherical shape, an ellipsoid shape, or an ovoid shape for each of the first particles and providing a star polyhedral shape for each of the second particles may increase or maximize the contact between the first particles and the second particles.

[0035] Each of the first particles may have a first size, and each of the second particles may have a second size.

[0036] The first size may be different from the second size.

[0037] The first size may be the same as the second size.

[0038] Advantageously, providing the same first size and second size may facilitate the uniform distribution of a plurality of first particles within a plurality of second particles. Advantageously, the uniform distribution of a plurality of first particles within a plurality of second particles may facilitate the efficient transfer of heat from the sensor material to the aerosol-forming substrate.

[0039] Each of the first particles may have a first cross-sectional dimension. The first cross-sectional dimension is a number-average cross-sectional dimension to accommodate intentional or manufacturing-tolerance-induced size variations of the first particles.

[0040] Each of the second particles may have a second cross-sectional dimension. The second cross-sectional dimension is a number-average cross-sectional dimension to accommodate intentional or manufacturing-tolerance-induced size variations of the second particles.

[0041] Preferably, the first cross-sectional dimension and the second cross-sectional dimension are the maximum cross-sectional dimensions of the first particles and the second particles, respectively. For particles having a spherical shape, the maximum cross-sectional dimension is the diameter of the sphere. For particles having an ellipsoid or ovoid shape, the maximum cross-sectional dimension is the major axis of the ellipsoid or ovoid shape.

[0042] The first cross-sectional dimension may be different from the second cross-sectional dimension.

[0043] The first cross-sectional dimension may be the same as the second cross-sectional dimension. Advantageously, providing the same first and second cross-sectional dimensions may facilitate the uniform distribution of a plurality of first particles within a plurality of second particles. Advantageously, the uniform distribution of a plurality of first particles within a plurality of second particles may facilitate the efficient transfer of heat from the sensor material to the aerosol-forming substrate.

[0044] The maximum first cross-sectional dimension of the first particles is preferably at least 0.05 mm, more preferably at least 0.1 mm, more preferably at least 0.15 mm, more preferably at least 0.2 mm, more preferably at least 0.25 mm, more preferably at least 0.5 mm, more preferably at least 0.75 mm, more preferably at least 1 mm. Preferably, the maximum first cross-sectional dimension of the first particles does not exceed 10 mm, more preferably does not exceed 9 mm, more preferably does not exceed 8 mm, more preferably does not exceed 6 mm, more preferably does not exceed 5 mm. As described below, when the outer wall of the capsule is provided with holes to form air inlets and outlets, it may be preferable to provide relatively large first particles within these ranges. The relatively large maximum size of the first particles can ensure that the first particles are not lost through the holes in the outer wall of the capsule.

[0045] The maximum second cross-sectional dimension of the second particles is preferably at least 0.05 mm, more preferably at least 0.1 mm, more preferably at least 0.15 mm, more preferably at least 0.2 mm, more preferably at least 0.25 mm, more preferably at least 0.5 mm, more preferably at least 0.75 mm, more preferably at least 1 mm. Preferably, the maximum second cross-sectional dimension of the second particles does not exceed 10 mm, more preferably does not exceed 9 mm, more preferably does not exceed 8 mm, more preferably does not exceed 6 mm, more preferably does not exceed 5 mm. As described below, when the outer wall of the capsule is provided with holes to form air inlets and outlets, it may be preferable to provide relatively large second particles within these ranges. The relatively large maximum size of the second particles can ensure that the second particles are not lost through the holes in the outer wall of the capsule.

[0046] Each of the first particles in the first particles may have a first mass. The first mass is the number-average mass in order to accommodate intentional or manufacturing tolerance-induced variations in the mass of the first particles.

[0047] Each of the second particles in the second particles may have a second mass. The second mass is the number-average mass in order to accommodate intentional or manufacturing tolerance-induced variations in the mass of the second particles.

[0048] The first mass may be different from the second mass.

[0049] Preferably, the difference between the first mass and the second mass is less than 10% of the first mass. Most preferably, the first mass can be the same as the second mass. Advantageously, providing the same first mass and second mass can facilitate the uniform distribution of a plurality of first particles within a plurality of second particles. Advantageously, the uniform distribution of a plurality of first particles within a plurality of second particles can facilitate the efficient transfer of heat from the sensor material to the aerosol-forming substrate.

[0050] The first mass is preferably at least 0.05 micrograms, more preferably at least 0.1 micrograms, more preferably at least 0.2 micrograms, more preferably at least 0.3 micrograms, more preferably at least 0.4 micrograms, more preferably at least 0.5 micrograms, more preferably at least 0.6 micrograms, more preferably at least 0.7 micrograms, more preferably at least 0.8 micrograms, more preferably at least 0.9 micrograms, more preferably at least 1 microgram, more preferably at least 10 micrograms, more preferably at least 100 micrograms, more preferably at least 200 micrograms, more preferably at least 500 micrograms, more preferably at least 1 milligram. The first mass is preferably not more than 600 milligrams, more preferably not more than 500 milligrams, more preferably not more than 400 milligrams, more preferably not more than 300 milligrams, more preferably not more than 200 milligrams, more preferably not more than 100 milligrams, more preferably not more than 50 milligrams, more preferably not more than 10 milligrams.

[0051] The second mass is preferably at least 0.05 micrograms, more preferably at least 0.1 micrograms, more preferably at least 0.2 micrograms, more preferably at least 0.3 micrograms, more preferably at least 0.4 micrograms, more preferably at least 0.5 micrograms, more preferably at least 0.6 micrograms, more preferably at least 0.7 micrograms, more preferably at least 0.8 micrograms, more preferably at least 0.9 micrograms, more preferably at least 1 microgram, more preferably at least 10 micrograms, more preferably at least 100 micrograms, more preferably at least 200 micrograms, more preferably at least 500 micrograms, more preferably at least 1 milligram. The second mass is preferably not more than 600 milligrams, more preferably not more than 500 milligrams, more preferably not more than 400 milligrams, more preferably not more than 300 milligrams, more preferably not more than 200 milligrams, more preferably not more than 100 milligrams, more preferably not more than 50 milligrams, more preferably not more than 10 milligrams.

[0052] Each first particle in the first particles can have a first density. The first density is a number-average density to accommodate intentional or manufacturing-tolerance-induced density variations of the first particles.

[0053] Each second particle in the second particles can have a second density. The second density is a number-average density to accommodate intentional or manufacturing-tolerance-induced density variations of the second particles.

[0054] The first density can be different from the second density.

[0055] Preferably, the difference between the first density and the second density is less than 10% of the first density. Most preferably, the first density may be the same as the second density. Advantageously, providing the same first density and second density can facilitate the uniform distribution of the plurality of first particles within the plurality of second particles. Advantageously, the uniform distribution of the plurality of first particles within the plurality of second particles can facilitate the efficient transfer of heat from the sensor material to the aerosol-forming substrate.

[0056] The first density is preferably at least 0.1 mg / mm3, more preferably at least 0.2 mg / mm3, more preferably at least 0.25 mg / mm3, more preferably at least 0.3 mg / mm3, more preferably at least 0.35 mg / mm3, more preferably at least 0.4 mg / mm3, more preferably at least 0.45 mg / mm3, more preferably at least 0.5 mg / mm3, more preferably at least 0.55 mg / mm3, more preferably at least 0.6 mg / mm3, more preferably at least 0.65 mg / mm3, more preferably at least 0.7 mg / mm3, more preferably at least 0.75 mg / mm3, more preferably at least 0.8 mg / mm3. The first density is preferably not more than 2 mg / mm3, more preferably not more than 1.95 mg / mm3, more preferably not more than 1.9 mg / mm3, more preferably not more than 1.85 mg / mm3, more preferably not more than 1.8 mg / mm3, more preferably not more than 1.75 mg / mm3, more preferably not more than 1.7 mg / mm3, more preferably not more than 1.65 mg / mm3, more preferably not more than 1.6 mg / mm3, more preferably not more than 1.55 mg / mm3, more preferably not more than 1.5 mg / mm3, more preferably not more than 1.45 mg / mm3, more preferably not more than 1.4 mg / mm3, more preferably not more than 1.35 mg / mm3, more preferably not more than 1.3 mg / mm3, more preferably not more than 1.25 mg / mm3, more preferably not more than 1.2 mg / mm3.

[0057] The second density is preferably at least 0.1 mg / mm³, more preferably at least 0.2 mg / mm³, more preferably at least 0.25 mg / mm³, more preferably at least 0.3 mg / mm³, more preferably at least 0.35 mg / mm³, more preferably at least 0.4 mg / mm³, more preferably at least 0.45 mg / mm³, more preferably at least 0.5 mg / mm³, more preferably at least 0.55 mg / mm³, more preferably at least 0.6 mg / mm³, more preferably at least 0.65 mg / mm³, more preferably at least 0.7 mg / mm³, more preferably at least 0.75 mg / mm³, more preferably at least 0.8 mg / mm³. The second density is preferably not more than 2 mg / mm³, more preferably not more than 1.95 mg / mm³, more preferably not more than 1.9 mg / mm³, more preferably not more than 1.85 mg / mm³, more preferably not more than 1.8 mg / mm³, more preferably not more than 1.75 mg / mm³, more preferably not more than 1.7 mg / mm³, more preferably not more than 1.65 mg / mm³, more preferably not more than 1.6 mg / mm³, more preferably not more than 1.55 mg / mm³, more preferably not more than 1.5 mg / mm³, more preferably not more than 1.45 mg / mm³, more preferably not more than 1.4 mg / mm³, more preferably not more than 1.35 mg / mm³, more preferably not more than 1.3 mg / mm³, more preferably not more than 1.25 mg / mm³, more preferably not more than 1.2 mg / mm³.

[0058] Preferably, the ratio of the total number of the first particles to the total number of the second particles in the lumen is between 0.2:1 and 5:1, more preferably between 0.3:1 and 4:1, more preferably between 0.4:1 and 3.5:1, more preferably between 0.5:1 and 3:1, more preferably between 0.6:1 and 2.5:1, more preferably between 0.7:1 and 2:1, more preferably between 0.8:1 and 1.5:1, more preferably between 0.9:1 and 1.1:1, and most preferably about 1:1. Advantageously, providing a ratio of the total number of the first particles to the total number of the second particles within these ranges can facilitate efficient and uniform heating of the aerosol-forming substrate by the sensing material.

[0059] Preferably, the ratio of the total mass of the first particles to the total mass of the second particles in the inner cavity is between 0.2 to 1 and 5 to 1, more preferably between 0.3 to 1 and 4 to 1, more preferably between 0.4 to 1 and 3.5 to 1, more preferably between 0.5 to 1 and 3 to 1, more preferably between 0.6 to 1 and 2.5 to 1, more preferably between 0.7 to 1 and 2 to 1, more preferably between 0.8 to 1 and 1.5 to 1, more preferably between 0.9 to 1 and 1.1 to 1, and most preferably about 1 to 1. Advantageously, providing a ratio of the total mass of the first particles to the total mass of the second particles within these ranges can facilitate efficient and uniform heating of the aerosol-forming substrate by the susceptor material.

[0060] Each of the second particles may have a homogeneous structure. Advantageously, a homogeneous structure can simplify the manufacture of the second particles. Each of the second particles may include solid particles of the susceptor material. Each of the second particles may have a uniform density.

[0061] Each of the second particles may have a heterogeneous structure. Advantageously, a heterogeneous structure can facilitate providing at least one of a desired size, mass, and density to each second particle. Each of the second particles may have a non-uniform density.

[0062] Each of the second particles may include a shell of the susceptor material and a void defined by the shell of the susceptor material. The void may be at least partially filled with a non-susceptor material. The shell of the susceptor material may have a first density, and the non-susceptor material may have a second density, where the second density is less than the first density. The non-susceptor material may include a non-conductive foam. The void may be free of solid or liquid material. The void may be filled with a gas. The gas may include air. The gas may include an inert gas. The void may include a partial vacuum or a vacuum.

[0063] Each of the second particles may include a multi-layer susceptor material. The multi-layer susceptor material may include a first layer and a second layer, the first layer including a first susceptor material and the second layer including a second susceptor material, where the first susceptor material is different from the second susceptor material. The first susceptor material may have a first density, and the second susceptor material may have a second density, where the first density is different from the second density.

[0064] Each of the second particles may have at least one of a size and a shape to increase the surface area of the second particle. Advantageously, increasing the surface area of each second particle can facilitate the transfer of heat from the susceptor material to the aerosol-forming substrate.

[0065] Each of the second particles may include a plurality of fins. Preferably, each fin is formed of a sensor material. Each of the second particles may include a plurality of disks or plates of the sensor material, where each disk or plate forms one of the plurality of fins. The following optional or preferred features for embodiments in which each of the second particles includes a plurality of disks may equally apply to embodiments in which each of the second particles includes a plurality of plates. Preferably, the disks are arranged in a stack. Preferably, the disks are spaced apart from each other. Preferably, the disks are connected to each other by a central post. Preferably, the central post is formed of the sensor material.

[0066] The capsule may include a single sensor element, where the single sensor element includes the sensor material. As used herein, the term "single sensor element" refers to a sensor element that is the sole sensor element within the capsule.

[0067] The first particle may include any of the optional or preferred features described above.

[0068] The single sensor element may have any suitable size or shape. The single sensor element may have a convex shape. The single sensor element may have a planar shape. The single sensor element may have an elongated shape. The single sensor element may have a shape selected from a strip, a pin, a cylinder, a sphere, an ellipsoid, an ovoid, a sheet, a disk, a cone, and a frustum of a cone.

[0069] Another optional and preferred feature described below applies to embodiments in which the capsule includes a plurality of second particles and to embodiments in which the capsule includes a single sensor element.

[0070] Preferably, the sensor material includes at least one metal. The sensor material may include at least one metal alloy. The sensor material may include a foam.

[0071] Preferably, the sensor material includes a ferromagnetic metal material. The sensor material may include at least one of ferrite iron, ferromagnetic steel, stainless steel, and aluminum. Different materials will generate different amounts of heat when positioned within an electromagnetic field having similar frequency and field strength values. Thus, the sensor material can be selected to provide a desired power dissipation within a known electromagnetic field.

[0072] In embodiments in which the sensor material includes stainless steel, the sensor material may include at least one 400 series stainless steel. Suitable 400 series stainless steels include grade 410, grade 420, and grade 430.

[0073] The sensor material may include metal wool. The metal wool may be formed of any of the metal sensor materials described herein.

[0074] The sensor material may include metal foam. The metal foam may be formed of any of the metal sensor materials described herein.

[0075] The sensor material may include a protective coating that encapsulates the surface of the sensor material. The protective coating can prevent direct contact between the sensor material and the aerosol-forming substrate. Advantageously, this can prevent unwanted chemical reactions between the sensor material and the aerosol-forming substrate. The protective coating may include at least one of glass and ceramic.

[0076] Preferably, each of the first particles does not include the sensor material. Advantageously, providing first particles that do not include the sensor material can simplify the manufacture of the first particles.

[0077] Preferably, the aerosol-forming substrate includes a solid aerosol-forming substrate.

[0078] Preferably, the aerosol-forming substrate includes at least one of nicotine and tobacco. Preferably, the aerosol-forming substrate includes nicotine.

[0079] As used herein in reference to the present invention, the term "nicotine" is used to describe nicotine, nicotine base, or nicotine salts. In embodiments where the aerosol-forming substrate contains nicotine base or nicotine salts, the amounts of nicotine recited herein are the amounts of free-base nicotine or protonated nicotine, respectively.

[0080] The aerosol-forming substrate may include natural nicotine or synthetic nicotine. Nicotine may include one or more nicotine salts. One or more nicotine salts may be selected from: nicotine lactate, nicotine citrate, nicotine pyruvate, nicotine hydrogen tartrate, nicotine benzoate, nicotine pectinate, nicotine alginate, and nicotine salicylate.

[0081] Nicotine may include tobacco extracts.

[0082] Preferably, the aerosol-forming substrate contains at least 0.5 wt% nicotine by dry weight. More preferably, the aerosol-forming substrate contains at least 1 wt% nicotine by dry weight. Even more preferably, the aerosol-forming substrate contains at least 2 wt% nicotine by dry weight. Additionally, or alternatively, the aerosol-forming substrate preferably includes less than 10 wt% nicotine by dry weight. More preferably, the aerosol-forming substrate includes less than 8 wt% nicotine by dry weight. Even more preferably, the aerosol-forming substrate includes less than 6 wt% nicotine by dry weight.

[0083] The aerosol-forming substrate may contain one or more carboxylic acids. Advantageously, including one or more carboxylic acids in the aerosol-forming substrate can produce nicotine salts.

[0084] The one or more carboxylic acids include one or more of lactic acid and levulinic acid. Advantageously, the inventors have found that lactic acid and levulinic acid are particularly good carboxylic acids for producing nicotine salts.

[0085] Preferably, the aerosol-forming substrate comprises at least 0.5% by weight of carboxylic acid based on dry weight. More preferably, the aerosol-forming substrate comprises at least 1% by weight of carboxylic acid based on dry weight. More preferably, the aerosol-forming substrate comprises at least 2% by weight of carboxylic acid based on dry weight.

[0086] Additionally, or alternatively, the aerosol-forming substrate preferably comprises less than 15% by weight of carboxylic acid based on dry weight. More preferably, the aerosol-forming substrate preferably comprises less than 10% by weight of carboxylic acid based on dry weight. More preferably, the aerosol-forming substrate preferably comprises less than 5% by weight of carboxylic acid based on dry weight. For example, the aerosol-forming substrate may comprise between 0.5% and 15% by weight of carboxylic acid, or between 1% and 10% by weight of carboxylic acid, or between 2% and 5% by weight of carboxylic acid.

[0087] The aerosol-forming substrate may include at least one aerosol-forming agent. The aerosol-forming substrate may comprise at least 15% by weight of aerosol-forming agent based on dry weight. Preferably, the aerosol-forming substrate comprises at least 20% by weight of aerosol-forming agent based on dry weight. More preferably, the aerosol-forming substrate comprises at least 25% by weight of aerosol-forming agent based on dry weight. More preferably, the aerosol-forming substrate comprises at least 30% by weight of aerosol-forming agent based on dry weight. More preferably, the aerosol-forming substrate comprises at least 35% by weight of aerosol-forming agent based on dry weight. More preferably, the aerosol-forming substrate comprises at least 40% by weight of aerosol-forming agent based on dry weight. More preferably, the aerosol-forming substrate comprises at least 45% by weight of aerosol-forming agent based on dry weight. More preferably, the aerosol-forming substrate comprises at least 50% by weight of aerosol-forming agent based on dry weight.

[0088] Preferably, the aerosol-forming substrate comprises no more than 80% by weight based on dry weight. More preferably, the second aerosol-forming substrate comprises no more than 75% by weight based on dry weight. More preferably, the second aerosol-forming substrate comprises no more than 70% by weight based on dry weight.

[0089] Suitable aerosol-forming agents included in the aerosol-forming substrate are known in the art and include, but are not limited to: polyols such as triethylene glycol, propylene glycol, 1,3-butanediol, and glycerol; esters of polyols such as glycerol mono-, di-, or triacetate; and aliphatic esters of mono-, di-, or polycarboxylic acids such as dimethyl dodecanedioate and dimethyl tetradecanedioate.

[0090] The aerosol-forming substrate may comprise a gel composition containing nicotine, at least one gelling agent, and an aerosol-forming agent. The gel composition is preferably substantially tobacco-free.

[0091] The gel composition preferably contains at least 50% by weight, more preferably at least 60% by weight, and even more preferably at least 70% by weight of the aerosol-forming agent, based on dry weight. The gel composition may contain up to 80% by weight of the aerosol-forming agent. The aerosol-forming agent in the gel composition is preferably glycerol.

[0092] The gel composition preferably contains at least one gelling agent. Preferably, the total amount of the gelling agent contained in the gel composition is in the range of about 0.4% to about 10% by weight, or about 0.5% to about 8% by weight, or about 1% to about 6% by weight, or about 2% to about 4% by weight, or about 2% to about 3% by weight.

[0093] The term "gelling agent" refers to a compound that, when added to a 50% by weight water / 50% by weight glycerol mixture in an amount of about 0.3% by weight, homogeneously forms a solid medium or support matrix that results in a gel. Gelling agents include, but are not limited to, hydrogen bond crosslinking gelling agents and ionic crosslinking gelling agents.

[0094] The term "hydrogen bond crosslinking gelling agent" refers to a gelling agent that forms non-covalent crosslinking bonds or physical crosslinking bonds via hydrogen bonds.

[0095] The hydrogen bond crosslinking gelling agent may include one or more of galactomannan, gelatin, agarose, konjac gum, or agar. The hydrogen bond crosslinking gelling agent may preferably include agar.

[0096] The term "ionic crosslinking gelling agent" refers to a gelling agent that forms non-covalent crosslinking bonds or physical crosslinking bonds via ionic bonds.

[0097] The ionic crosslinking gelling agent may include low acyl gellan gum, pectin, κ-carrageenan, ι-carrageenan, or alginate. The ionic crosslinking gelling agent may preferably include low acyl gellan gum.

[0098] The gelling agent may include one or more biopolymers. The biopolymers may be formed from polysaccharides.

[0099] Biopolymers include, for example, gellan gum (natural, low acyl gellan gum, high acyl gellan gum, preferably low acyl gellan gum), xanthan gum, alginate (algic acid), agar, guar gum, etc. The composition may preferably include xanthan gum. The composition may include two biopolymers. The composition may include three biopolymers. The composition may include two biopolymers in substantially equal weights. The composition may include three biopolymers in substantially equal weights.

[0100] The gel composition may further comprise a thickening agent. A thickening agent in combination with a hydrogen bond crosslinked gelling agent and an ionic crosslinked gelling agent surprisingly appears to support a solid medium and maintain the gel composition, even when the gel composition comprises a high level of glycerol.

[0101] The term "thickening agent" refers to a compound that, when homogeneously added in an amount of 0.3% by weight to a mixture of 50% by weight water / 50% by weight glycerol at 25 degrees Celsius, increases the viscosity without causing gel formation and the mixture remains or retains its fluidity.

[0102] The gel composition preferably comprises a thickening agent in the range of from about 0.2% to about 5% by weight, or from about 0.5% to about 3% by weight, or from about 0.5% to about 2% by weight, or from about 1% to about 2% by weight.

[0103] The thickening agent may include one or more of xanthan gum, carboxymethyl cellulose, microcrystalline cellulose, methyl cellulose, gum arabic, guar gum, lambda-carrageenan or starch. The thickening agent may preferably include xanthan gum.

[0104] The gel composition may further comprise a divalent cation. Preferably, the divalent cation includes calcium ions, such as calcium lactate in solution. For example, divalent cations (such as calcium ions) can help form the gel of a composition comprising a gelling agent such as an ionic crosslinked gelling agent. The ionic effect can assist in gel formation. The divalent cation may be present in the gel composition in the range of from about 0.1% to about 1% by weight or about 0.5% by weight.

[0105] The gel composition may further comprise an acid. The acid may include a carboxylic acid. The carboxylic acid may include a keto group. Preferably, the carboxylic acid may include a keto group having less than about 10 carbon atoms, or less than about 6 carbon atoms, or less than about 4 carbon atoms, such as levulinic acid or lactic acid. Preferably, the carboxylic acid has three carbon atoms (such as lactic acid).

[0106] The gel composition preferably includes some water. When the gel composition includes some water, the gel composition is more stable.

[0107] Preferably, the gel composition includes water in the range of from about 8% to about 32% by weight, or from about 15% to about 25% by weight, or from about 18% to about 22% by weight, or about 20% by weight.

[0108] The outer wall of the capsule may be formed of any suitable material. Preferably, the outer wall of the capsule is formed of an air-impermeable material, most preferably an air-impermeable polymeric material. This ensures that air does not pass through the outer wall of the capsule except through the pores provided specifically for the airflow during use. Thus, the airflow through the capsule during use can be effectively controlled.

[0109] The outer wall of the capsule may comprise a polymeric material or a cellulose-based material. For example, the outer wall of the capsule may be made of one or more polymers compatible with nicotine, including medical-grade polymers such as medical resin polymethyl methacrylate (PMMA), Chevron Phillips K- styrene-butadiene copolymer (SBC), Arkema specialty polymers and Clear, DOW (Health+ TM ) low-density polyethylene (LDPE), DOW TM LDPE 91003, DOW TM LDPE 91020 (MFI 2.0; density 923), ExxonMobil TM polypropylene (PP) PP1013H1, PP1014H1 and PP9074MED, Trinseo CALIBRE TM polycarbonate (PC) 2060-SERIES.

[0110] Alternatively, the outer wall of the capsule may be formed from one or more materials selected from: polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polylactic acid (PLA), cellulose acetate (CA), gelatin, and hydroxypropyl methylcellulose (HPMC).

[0111] The capsule is preferably of a capsule shape in the form of a spherical-cylinder, having a cylindrical portion defined by a cylindrical wall and rounded hemispherical end walls at each end of the cylindrical portion. This type of capsule is commonly used in the pharmaceutical industry. Alternatively, the capsule may be spherical or oval.

[0112] Preferably, the capsule is a two-part capsule having two separate parts that fit together to enclose the capsule and retain the contents. The two separate parts may fit together by friction fit without the need for an adhesive. Alternatively, an adhesive may be used to seal the two parts together.

[0113] Preferably, the capsule comprises a first part and a second part, wherein the second part has a smaller outer diameter than the first part such that the end of the second part can be inserted into the open end of the first part to enclose the capsule. Preferably, when the capsule is installed within a hollow tubular element, the second part of the capsule is disposed downstream of the first part.

[0114] In such embodiments, the outer diameters of the first and second portions of the bladder may be adapted such that only the second portion of the bladder can be received within the hollow tubular element. The outer diameter of the first portion of the bladder is adapted to be greater than the inner diameter of the hollow tubular element such that the first portion of the bladder cannot be received within the hollow tubular element and remains outside the hollow tubular element at the upstream end. Preferably, the second portion of the bladder is retained within the hollow tubular element by a friction fit. The first portion prevents the bladder from being further pushed into the hollow tubular element.

[0115] Alternatively, in such embodiments, the bladder may be fully inserted into the hollow tubular element, and the outer diameters of the first and second portions of the bladder may be adapted such that the outer diameter of the second portion is less than the inner diameter of the hollow tubular element. This provides a space between the second portion of the bladder and the wall of the hollow tubular element such that an air flow can pass around the second portion of the bladder. As described below, such an arrangement may be beneficial in embodiments where it is desired to locate an air outlet on the cylindrical wall of the bladder. The outer diameter of the first portion of the bladder is preferably adapted such that the first portion of the bladder is retained within the hollow tubular article by a friction fit. Alternatively, the first portion of the bladder may be retained in place by a suitable adhesive. Any of these arrangements preferably substantially prevents an air flow around the first portion of the bladder downstream of the second portion of the bladder.

[0116] Preferably, the lumen of the bladder has a volume of at least 250 cubic millimeters corresponding to 0.25 millimeters. This corresponds to the internal volume, or capacity, of the bladder. Preferably, the lumen of the bladder has a volume of at least 400 cubic millimeters (0.4 milliliters), more preferably at least 500 cubic millimeters (0.5 milliliters), more preferably at least 600 cubic millimeters (0.6 milliliters). The lumen of the bladder may be less than 2000 cubic millimeters (2 milliliters), or less than 1500 cubic millimeters (1.5 milliliters) or less than 1000 cubic millimeters (1 milliliter). For example, standard bladder sizes 000, 00, 0, 0, 1, 2, and 3 may be suitable.

[0117] The bladder preferably has a length of at least 10 millimeters, more preferably at least 12 millimeters, more preferably at least 15 millimeters, more preferably at least 18 millimeters. The length of the bladder is preferably less than 30 millimeters, more preferably less than 28 millimeters, more preferably less than 25 millimeters. For example, the bladder length may be between 10 millimeters and 30 millimeters, or between 12 millimeters and 28 millimeters, or between 15 millimeters and 25 millimeters, or between 18 millimeters and 25 millimeters. The bladder length may be about 20 millimeters.

[0118] The sac preferably has a maximum diameter of at least 5 mm, more preferably at least 5.5 mm, more preferably at least 6 mm, more preferably at least 6.5 mm. The maximum diameter of the sac is preferably less than 9 mm, more preferably less than 8.5 mm, more preferably less than 8 mm, more preferably less than 7.5 mm. For example, the maximum diameter of the sac can be between 5 mm and 9 mm, or between 5.5 mm and 8.5 mm, or between 6 mm and 8 mm, or between 6.5 mm and 7.5 mm. The maximum diameter of the sac can be about 7 mm.

[0119] The inner cavity of the sac preferably contains at least 50 mg of the aerosol-forming substrate, more preferably at least 100 mg of the aerosol-forming substrate, more preferably at least 150 mg of the aerosol-forming substrate. The inner cavity can contain up to 1000 mg of the aerosol-forming substrate, or up to 750 mg of the aerosol-forming substrate, or up to 500 mg of the aerosol-forming substrate, or up to 250 mg of the aerosol-forming substrate. For example, the inner cavity of the sac can contain the aerosol-forming substrate between 50 mg and 1000 mg, or between 100 mg and 750 mg, or between 150 mg and 500 mg, or between 150 mg and 250 mg.

[0120] Preferably, the weight of the aerosol-forming substrate in the sac corresponds to at least 0.1 mg / mm³ of the inner cavity. This corresponds to the total weight of the aerosol-forming substrate divided by the total volume of the inner cavity. Preferably, the weight of the aerosol-forming substrate in the sac corresponds to at least 0.15 mg / mm³ of the inner cavity, more preferably at least 0.2 mg / mm³ of the inner cavity. The weight of the aerosol-forming substrate in the sac can correspond to less than 2 mg / mm³ of the inner cavity, or less than 1 mg / mm³ of the inner cavity, or less than 0.5 mg / mm³ of the inner cavity. For example, the weight of the aerosol-forming substrate in the sac can correspond to the inner cavity between 0.1 mg / mm³ and 2 mg / mm³, or between 0.15 mg / mm³ and 1 mg / mm³, or between 0.2 mg / mm³ and 0.5 mg / mm³.

[0121] The filling percentage of the first particles and the second particles or the first particles and the single sensor element in the sac is preferably at least 50%, more preferably at least 60%, more preferably at least 70%. The filling percentage is preferably less than 90%. The filling percentage corresponds to the percentage of the inner cavity of the sac occupied by the first particles and the second particles or the first particles and the single sensor element. In other words, the filling percentage corresponds to the percentage of the volume of the inner cavity occupied by the first particles and the second particles or the first particles and the sensor element. It may be advantageous to maintain some empty space in the inner cavity to allow the airflow through the inner cavity and allow the aerosol-forming substrate to be uniformly heated.

[0122] The capsule can be configured to provide one or more air flow paths through the capsule during heating. Advantageously, the one or more air flow paths enable the aerosol generated from the aerosol-forming substrate to be drawn through the aerosol-generating article and delivered to the consumer.

[0123] The capsule can be initially sealed and airtight, but is adapted to create an air flow path when the aerosol-generating article is inserted into the aerosol-generating device, for example, by inserting an internal heating element or a piercing element that pierces the outer wall of the capsule.

[0124] Alternatively and preferably, the capsule includes at least one air inlet and at least one air outlet in the outer wall of the capsule. Preferably, the at least one air inlet and the at least one air outlet define one or more air flow paths through the lumen of the capsule between the at least one air inlet and the at least one air outlet. The at least one air outlet is disposed downstream of the at least one air inlet.

[0125] Preferably, each of the first particles is larger than each of the at least one air inlet and the at least one air outlet. Advantageously, this can prevent the first particles from being lost from the capsule through the at least one air inlet and the at least one air outlet.

[0126] Preferably, each of the second particles is larger than each of the at least one air inlet and the at least one air outlet. Advantageously, this can prevent the second particles from being lost from the capsule through the at least one air inlet and the at least one air outlet.

[0127] Preferably, the capsule includes a plurality of air inlets. For example, the capsule can include between 2 and 6 air inlets.

[0128] Preferably, the capsule includes a plurality of air outlets. For example, the capsule can include between 2 and 6 air outlets. The number of air outlets can be the same as or different from the number of air inlets. It may be advantageous to provide a greater number of air outlets than air inlets because the air outlets need to allow the aerosol generated within the capsule to flow out of the capsule into the hollow tubular element.

[0129] The number and size of the air inlets and air outlets can be adjusted to control the air flow through the capsule and also to control the draw resistance (RTD) of the aerosol-generating article. In some embodiments, the capsule will provide the main RTD source within the article, and thus the overall RTD of the aerosol-generating article may be highly dependent on the RTD of the capsule.

[0130] Each air inlet and each air outlet is preferably in the form of a hole through the outer wall of the capsule. Preferably, each hole is cylindrical, although other shapes may be suitable. The diameter of each hole should be large enough such that the hole cannot be easily blocked, for example, by dust. However, the diameter of each hole should also be adjusted depending on the form and nature of the aerosol-forming substrate such that the aerosol-forming substrate does not escape from the lumen through the hole.

[0131] Preferably, each hole forming an air inlet or an air outlet has a diameter of at least 0.2 mm, more preferably at least 0.25 mm, more preferably at least 0.3 mm, more preferably at least 0.35 mm, more preferably at least 0.4 mm, more preferably at least 0.5 mm. The diameter of each hole may be less than 2 mm, or less than 1.8 mm, or less than 1.7 mm, or less than 1.6 mm, or less than 1.5 mm, or less than 1.4 mm, or less than 1.3 mm, or less than 1.2 mm, or less than 1.1 mm, or less than 1 mm, or less than 0.9 mm, or less than 0.8 mm. For example, the diameter of each hole may be between 0.2 mm and 2 mm, or between 0.25 mm and 1.8 mm, or between 0.3 mm and 1.6 mm, or between 0.35 mm and 1.4 mm, or between 0.4 mm and 1.2 mm, or between 0.45 mm and 1 mm, or between 0.5 mm and 0.9 mm, or between 0.5 mm and 0.8 mm.

[0132] In cases where multiple air inlets or air outlets are provided, the corresponding holes should be spaced sufficiently apart such that the presence of the holes does not adversely affect the structural integrity of the capsule. For example, the holes are preferably spaced at least 1 mm apart from each other.

[0133] At least one air outlet is preferably at least 5 mm downstream of at least one air inlet, more preferably at least 8 mm downstream of at least one air inlet, and more preferably at least 10 mm downstream of at least one air inlet. This spacing enables the length of the airflow path through the capsule to be maximized.

[0134] At least one air outlet is preferably located at the downstream end of the capsule. In cases where the capsule has a conventional capsule shape (the conventional capsule shape having an elongate cylindrical body and rounded end walls), at least one air outlet is preferably provided on the downstream end wall.

[0135] At least one air inlet may be located at the upstream end of the capsule. For example, in the case where the capsule has the conventional capsule shape as described above, at least one air inlet may be provided on the upstream end wall. However, in some embodiments, it may be advantageous to locate at least one air inlet a certain distance downstream of the upstream end. For example, at least one air inlet may be provided at least 2 millimeters downstream of the upstream end of the capsule, or at least 3 millimeters downstream of the upstream end of the capsule, or at least 4 millimeters downstream of the upstream end of the capsule, or at least 5 millimeters downstream of the upstream end of the capsule. In the case where multiple air inlets are provided, all air inlets should be provided at least this distance from the upstream end, even when the position of the air inlets varies along the length of the capsule.

[0136] In a preferred embodiment, the capsule includes a cylindrical wall and rounded end walls at the upstream and downstream ends of the cylindrical wall (such as in the conventional capsule shape), and at least one air inlet may advantageously be provided in the cylindrical wall downstream of the upstream end wall.

[0137] This positioning of at least one air inlet away from the upstream end of the capsule may be particularly beneficial when the aerosol-forming substrate is in the form of a gel composition or any other substrate type that melts or becomes more viscous upon heating. By locating at least one air inlet away from the upstream end of the chamber (where the molten substrate can accumulate), this reduces or minimizes the risk of leakage of the aerosol-forming substrate from the capsule. The risk of the aerosol-forming substrate blocking the air inlet is also reduced or minimized.

[0138] The aerosol-generating article may include a hollow tubular element. The capsule may be located within the hollow tubular element. The capsule may be retained within the hollow tubular element by an interference fit.

[0139] The capsule may be located within the hollow tubular element such that at least one air inlet is not covered or blocked by the wall of the hollow tubular element, particularly in the case where at least one air inlet is provided on the cylindrical wall of the capsule (as described above). As described below, there are various suitable ways to achieve this.

[0140] The hollow tubular element may include one or more holes extending through the outer peripheral wall of the hollow tubular element, wherein the one or more holes are positioned to coincide with one or more air inlets on the capsule. With this arrangement, air can pass through the outer peripheral wall of the hollow tubular element from the outside of the hollow tubular element and into at least one air inlet.

[0141] The sac can be installed within a hollow tubular element such that a portion of the sac extends from the upstream end of the hollow tubular element, such that at least one air inlet is positioned outside the hollow tubular element. Preferably, at least 20% of the length of the sac, more preferably at least 30% of the length of the sac, protrudes from the hollow tubular element. Preferably, no more than 50% of the length of the sac protrudes from the hollow tubular element. Preferably, most of the sac is within the hollow tubular element such that the sac can be firmly held within the hollow tubular element. The hollow tubular element can include a flange or projection that extends inwards from the inner surface at the downstream end of the sac to prevent the sac from being pushed further downstream into the hollow tubular element. For example, the hollow tubular element can include an annular flange extending from the inner surface.

[0142] The sac can be provided with an outer diameter that is smaller than the inner diameter of the hollow tubular element. This arrangement provides a space between the outer surface of the sac and the inner surface of the hollow tubular element such that air can be transferred between the sac and the hollow tubular element to the at least one air inlet. In such embodiments, it may be desirable to block the flow of air from the upstream end of the hollow tubular element to at least one air outlet in the sac wall. In this way, the main air flow path is defined as passing through the sac and not around the outside of the sac. This can be achieved, for example, by providing an annular seal ring within the hollow tubular element around the sac that seals the space between the sac and the inner surface of the hollow tubular element at a position downstream of the at least one air inlet. Advantageously, the annular seal ring also facilitates holding the sac within the hollow tubular element.

[0143] In such embodiments, the outer diameter of the sac is preferably at least 0.2 millimeters smaller than the inner diameter of the hollow tubular element, more preferably at least 0.5 millimeters smaller than the inner diameter of the hollow tubular element, and more preferably at least 0.8 millimeters smaller than the inner diameter of the hollow tubular element. The outer diameter of the sac can be at most 2 millimeters smaller than the inner diameter of the hollow tubular element.

[0144] The inner surface of the hollow tubular element can be corrugated at the upstream end of the hollow tubular element to define a plurality of longitudinal channels circumferentially arranged to substantially coincide with the at least one air inlet. With this arrangement, air can enter the hollow tubular element through the longitudinal channels defined by the corrugated surface and travel along the sac to the at least one air inlet. The hollow tubular element is preferably corrugated only along a portion of its length from the upstream end and not along its entire length. Thus, the longitudinal channels preferably extend to a position upstream of the at least one air outlet such that there is no flow of air from the upstream end of the hollow tubular element to the at least one air outlet. In this way, the main air flow path is defined as passing through the sac and not around the outside of the sac.

[0145] Preferably, the hollow tubular element extends to the downstream end of the aerosol-generating article.

[0146] As used herein, the term "hollow tubular element" refers to a generally elongated element that defines a lumen or passage along a longitudinal axis of the hollow tubular element. In particular, the term "tubular" is used herein to refer to a tubular element having a substantially cylindrical cross-section and defining at least a passage extending between an upstream end and a downstream end of the tubular element. However, it should be understood that alternative geometries (e.g., alternative cross-sectional shapes) of the tubular element may be possible.

[0147] As described above, the capsule can be positioned at the upstream end of the hollow tubular element. The hollow tubular element can define a cavity downstream of the capsule, where the cavity extends along a part or all of the length of the hollow tubular element. The cavity can extend from the capsule to the downstream end of the aerosol-generating article. In such embodiments, the aerosol-generating article can thus be formed of only two elements: the capsule and the hollow tubular element. Alternatively, as described in more detail below, one or more filter segments can be provided within the hollow tubular element, at the downstream end of the hollow tubular element, or adjacent to the downstream end of the hollow tubular element.

[0148] The cavity defined within the hollow tubular element downstream of the capsule preferably has a length of at least 10 millimeters, more preferably at least 12 millimeters, and even more preferably at least 14 millimeters. The length of the cavity can be up to 40 millimeters, or up to 30 millimeters, or up to 25 millimeters. For example, the cavity can have a length between 10 millimeters and 40 millimeters, or between 12 millimeters and 30 millimeters, or between 14 millimeters and 25 millimeters.

[0149] The hollow tubular element preferably has a total length of at least 25 millimeters, more preferably at least 28 millimeters, more preferably at least 30 millimeters, more preferably at least 32 millimeters, more preferably at least 34 millimeters. The length of the hollow tubular element can be less than 50 millimeters, or less than 48 millimeters, or less than 45 millimeters, or less than 42 millimeters, or less than 40 millimeters. For example, the total length of the hollow tubular element can be between 25 millimeters and 50 millimeters, or between 28 millimeters and 48 millimeters, or between 30 millimeters and 45 millimeters, or between 32 millimeters and 42 millimeters, or between 34 millimeters and 40 millimeters.

[0150] The hollow tubular element can have an outer diameter between 5 millimeters and 12 millimeters, such as between 5 millimeters and 10 millimeters or between 6 millimeters and 8 millimeters. In a preferred embodiment, the hollow tubular element has an external diameter of 7.2 millimeters ± 10%.

[0151] The internal diameter of the hollow tubular element is preferably constant along the length of the hollow tubular element. The lumen or cavity of the hollow tubular element can have any cross-sectional shape. The lumen of the hollow tubular element can have a circular cross-sectional shape.

[0152] Preferably, the inner diameter of the hollow tubular element is at least 5 mm, more preferably at least 5.5 mm, more preferably at least 6 mm, more preferably at least 6.5 mm. The inner diameter of the hollow tubular element is preferably less than 9 mm, more preferably less than 8.5 mm, more preferably less than 8 mm, more preferably less than 7.5 mm. For example, the inner diameter may be between 5 mm and 9 mm, or between 5.5 mm and 8.5 mm, or between 6 mm and 6 mm, or between 6.5 mm and 7.5 mm. The inner diameter may be about 7 mm.

[0153] The hollow tubular element preferably has a wall thickness of at least 100 μm, more preferably at least 150 μm, more preferably at least 200 μm, more preferably at least 250 μm, more preferably at least 500 μm. The wall thickness of the hollow tubular element may be less than 2 mm, preferably less than 1.5 mm, and even more preferably less than 1.25 mm. The wall thickness of the hollow tubular element may be less than 1 mm. For example, the wall thickness of the hollow tubular element may be between 100 μm and 2 mm, or between 150 μm and 1.5 mm, or between 200 μm and 1.25 mm, or between 250 μm and 1 mm, or between 500 μm and 1 mm.

[0154] The hollow tubular element may comprise a paper-based material. The hollow tubular element may comprise at least one paper layer. The paper may be very hard paper. The paper may be curled paper, such as curled heat-resistant paper or curled parchment paper. Advantageously, the curled paper may form one or more air flow channels extending around the outside of the capsule. In embodiments where the capsule includes at least one of an air inlet and an air outlet in the cylindrical wall of the capsule, the one or more air flow channels may be particularly advantageous.

[0155] Preferably, the hollow tubular element is formed of cardboard. The hollow tubular element may be a cardboard tube. Advantageously, cardboard is a cost-effective material that provides a balance between being deformable to facilitate insertion of the article into the aerosol-generating device and being rigid enough to provide proper engagement of the article with the interior of the device. Thus, the cardboard tube may provide a suitable resistance to deformation or compression during use.

[0156] The hollow tubular element may be a paper tube. The hollow tubular element may be a tube formed by helically winding paper. The hollow tubular element may be formed of multiple paper layers. The paper may have a basis weight of at least about 50 g / m², at least about 60 g / m², at least about 70 g / m², or at least about 90 g / m².

[0157] The hollow tubular element may comprise a polymeric material. For example, the hollow tubular element may comprise a polymeric film. The polymeric film may comprise a cellulose film. The hollow tubular element may comprise high-density polyethylene (HDPE) or polyhydroxyalkanoate (PHA) fibers. The hollow tube may comprise a cellulose acetate tow.

[0158] In the case where the hollow tubular element comprises a cellulose acetate tow, the cellulose acetate tow may have a denier per filament between about 2 and about 4 and a total denier between about 25 and about 40.

[0159] In the aerosol-generating article according to the present invention, the hollow tubular element preferably provides a negligible draw resistance (RTD) level. The term "negligible RTD level" is used to describe a hollow tubular element or a hollow tubular element having a length of less than 1 mmHg / 10 mm, preferably less than 0.4 mmHg / 10 mm 2 of the hollow tubular element or a hollow tubular element, more preferably less than 0.1 mmHg / 10 mm 2 of the hollow tubular element or a hollow tubular element, even more preferably less than 0.1 mmHg / 10 mm 2 of the hollow tubular element or a hollow tubular element.

[0160] The RTD of the hollow tubular element is preferably less than or equal to about 10 mmHg 2 O. More preferably, the RTD of the hollow tubular element is less than or equal to about 5 mmHg 2 O. Even more preferably, the RTD of the hollow tubular element is less than or equal to about 2.5 mmHg 2 O. Even more preferably, the RTD of the hollow tubular element is less than or equal to about 2 mmHg 2 O. Even more preferably, the RTD of the hollow tubular element is less than or equal to about 1 mmHg 2 O.

[0161] The RTD of the hollow tubular element can be at least 0 mmHg 2 O, or at least about 0.25 mmHg 2 O, or at least about 0.5 mmHg 2 O, or at least about 1 mmHg 2 O.

[0162] In some embodiments, the RTD of the hollow tubular element is from about 0 mmHg 2 O to about 10 mmHg 2 O, preferably about 0.25 mmHg 2 O to about 10 mmHg 2 O, preferably about 0.5 mmHg 2 O to about 10 mmHg 2 O. In other embodiments, the RTD of the hollow tubular element is from about 0 mmHg 2 O to about 5 mmHg 2 O, preferably about 0.25 mmHg 2 O to about 5 mmHg 2 O, preferably about 0.5 mmHg 2 O to about 5 mmHg 2O. In other embodiments, the RTD of the hollow tubular element is about 1 millimeter H 2 O to about 5 millimeters H 2 O. In additional embodiments, the RTD of the hollow tubular element is about 0 millimeter H 2 O to about 2.5 millimeters H 2 O, preferably about 0.25 millimeter H 2 O to about 2.5 millimeters H 2 O, preferably about 0.5 millimeter H 2 O to about 2.5 millimeters H 2 O. In additional embodiments, the RTD of the hollow tubular element is about 0 millimeter H 2 O to about 2 millimeters H 2 O, preferably about 0.25 millimeter H 2 O to about 2 millimeters H 2 O, preferably about 0.5 millimeter H 2 O to about 2 millimeters H 2 O. In a particularly preferred embodiment, the RTD of the hollow tubular element is about 0 millimeter H 2 O.

[0163] As described above, the aerosol-generating article may include a downstream filter segment. The downstream filter segment may be installed within the hollow tubular element at the downstream end of the hollow tubular element. The downstream filter segment may extend to the downstream end of the hollow tubular element. The downstream end of the downstream filter segment may define the downstream end of the aerosol-generating article. Including the downstream filter segment within the hollow tubular element may be useful for providing a desired level of RTD to the aerosol-generating article.

[0164] The downstream filter segment is located downstream of the capsule. Preferably, the capsule and the downstream filter segment are spaced apart in the longitudinal direction such that a cavity is defined between the capsule and the downstream filter segment. Preferably, the downstream filter segment is located at least 5 millimeters downstream of the downstream end of the capsule, more preferably at least 8 millimeters downstream of the downstream end of the capsule, more preferably at least 10 millimeters downstream of the downstream end of the capsule, more preferably at least 15 millimeters downstream of the downstream end of the capsule. Preferably, the downstream filter segment is located less than 30 millimeters downstream of the downstream end of the capsule, more preferably less than 25 millimeters downstream of the downstream end of the capsule. The distance defined between the downstream end of the capsule and the downstream filter segment corresponds to the length of the cavity between the capsule and the downstream filter segment.

[0165] The downstream filter segment is preferably a solid rod, which may also be described as a "plain" rod and is non-tubular. The filter segment preferably has a substantially uniform cross-section.

[0166] The downstream filter segment is preferably formed of a fibrous filter material. The fibrous filter material can be used to filter the aerosol generated from the aerosol-forming substrate. Suitable fibrous filter materials will be known to those skilled in the art. Particularly preferably, at least one downstream filter segment includes a cellulose acetate filter segment formed of a cellulose acetate tow.

[0167] The downstream filter segment may optionally include a flavorant, which can be provided in any suitable form. For example, the downstream filter segment may include one or more capsules, beads or microparticles of the flavorant, or one or more wires or filaments carrying the flavor.

[0168] Preferably, the downstream filter segment has a low particulate filtration efficiency.

[0169] The downstream filter segment preferably has an outer diameter that is substantially equal to the inner diameter of the hollow tubular element, such that the downstream filter segment is held within the hollow tubular element by a friction fit.

[0170] Preferably, the outer diameter of the downstream filter segment is between 5 mm and 12 mm, more preferably between 6 mm and 10 mm, and even more preferably between 7 mm and 8 mm.

[0171] Unless otherwise stated, the draw resistance (RTD) of the component or the aerosol-generating article is measured according to ISO 6565-2015. RTD refers to the pressure required to force air through the full length of the component. The terms "pressure drop" or "draw resistance" of the component or article may also refer to "resistance to draw". Such terms generally refer to the measurement according to ISO 6565-2015, typically in a test at a temperature of 22 °C, a pressure of 101 kPa (about 760 Torr), and a relative humidity of 60%, at a volumetric flow rate of 17.5 ml / s at the output or downstream end of the component being measured. The conditions for smoking and the specifications of the smoking machine are set out in ISO standard 3308 (ISO 3308:2000). The conditioning and testing atmosphere are set out in ISO standard 3402 (ISO 3402:1999).

[0172] The draw resistance (RTD) of the downstream filter segment can be at least 0 mmH 2 O, or at least 3 mmH 2 O, or at least 6 mmH 2 O.

[0173] The RTD of the downstream filter segment can be no greater than 12 mmH 2 O, or no greater than 11 mmH 2 O, or no greater than 10 mmH 2 O.

[0174] As described above, the downstream filter segment may be formed of a fibrous filter material. The downstream filter segment may be formed of a porous material. The downstream filter segment may be formed of a biodegradable material. The downstream filter segment may be formed of a cellulose material such as cellulose acetate. For example, the downstream filter segment may be formed of a bundle of cellulose acetate fibers having a denier per filament between 10 and 15. For example, the downstream filter segment is formed of a relatively low density cellulose acetate tow (such as a cellulose acetate tow including fibers having a denier per filament of 12).

[0175] The downstream filter segment may be formed of a polylactic acid-based material. The downstream filter segment may be formed of a bioplastic material (preferably a starch-based bioplastic material). The downstream filter segment may be manufactured by injection molding or by extrusion. The bioplastic-based material is advantageous because it can provide a downstream filter segment structure that is simple and inexpensive to manufacture, has a specific and complex cross-sectional profile, which may include a plurality of relatively large air flow channels extending through the downstream filter segment material, which provides suitable RTD characteristics.

[0176] The length of the downstream filter segment may be at least 5 mm, or at least 8 mm, or at least 10 mm. The length of the downstream filter segment may be less than 20 mm, or less than 15 mm, or less than 12 mm. For example, the length of the downstream filter segment may be between 5 mm and 20 mm, or between 8 mm and 15 mm, or between 8 mm and 12 mm, or between 10 mm and 12 mm.

[0177] The downstream filter segment may be disposed downstream of the hollow tubular element. The downstream filter segment may extend between the hollow tubular element and the downstream end of the aerosol-generating article. The downstream filter segment may be connected to the hollow tubular element by means of a tipping wrapper.

[0178] The overall RTD of the aerosol-generating article may be at least 1 mm H 2 O. For example, the overall RTD of the aerosol-generating article may be at least 2 mm H 2 O, at least 3 mm H 2 O, at least 4 mm H 2 O, at least 5 mm H 2 O, at least 6 mm H 2 O, at least 7 mm H 2 O, at least 8 mm H 2 O, at least 9 mm H 2 O, at least 10 mm H 2 O, at least 15 mm H 2 O, at least 20 mm H 2 O, at least 30 mm H 2 O, at least 40 mm H2 O or at least 50 mm H 2 O.

[0179] The overall RTD of the aerosol - generating article may not exceed 180 mm H 2 O. For example, the overall RTD of the aerosol - generating article may not exceed 170 mm H 2 O, not exceeding 160 mm H 2 O, not exceeding 150 mm H 2 O or not exceeding 140 mm H 2 O.

[0180] The overall RTD of the aerosol - generating article may be between 1 mm H 2 O and 180 mm H 2 O. For example, the overall RTD of the aerosol - generating article may be between 5 mm H 2 O and 170 mm H 2 O, between 10 mm H 2 O and 160 mm H 2 O, between 20 mm H 2 O and 150 mm H 2 O, or between 50 mm H 2 O and 140 mm H 2 O.

[0181] The aerosol - generating article may have a total length of at least 40 mm, or at least 50 mm, or at least 60 mm.

[0182] The total length of the aerosol - generating article may be less than or equal to 90 mm, or less than or equal to 85 mm, or less than or equal to 80 mm.

[0183] In some embodiments, the total length of the aerosol - generating article is preferably from 40 mm to 70 mm, more preferably from 45 mm to 70 mm. In other embodiments, the total length of the aerosol - generating article is preferably from 40 mm to 60 mm, more preferably from about 45 mm to about 60 mm. In further embodiments, the total length of the aerosol - generating article is preferably from 40 mm to 50 mm, more preferably from 45 mm to 50 mm. In an exemplary embodiment, the total length of the aerosol - generating article is about 45 mm.

[0184] The aerosol - generating article may have an outer diameter of at least 5 mm, or at least 6 mm, or at least 7 mm.

[0185] The aerosol - generating article may have an outer diameter of less than or equal to about 12 mm, or less than or equal to about 10 mm, or less than or equal to about 8 mm.

[0186] In some embodiments, the aerosol-generating article has an outer diameter of from about 5 millimeters to about 12 millimeters, preferably from about 6 millimeters to about 12 millimeters, more preferably from about 7 millimeters to about 12 millimeters. In other embodiments, the aerosol-generating article has an outer diameter of from about 5 millimeters to about 10 millimeters, preferably from about 6 millimeters to about 10 millimeters, more preferably from about 7 millimeters to about 10 millimeters. In further embodiments, the aerosol-generating article has an outer diameter of from about 5 millimeters to about 8 millimeters, preferably from about 6 millimeters to about 8 millimeters, more preferably from about 7 millimeters to about 8 millimeters. In other embodiments, the aerosol-generating article has an outer diameter of less than 7 millimeters.

[0187] The outer diameter of the aerosol-generating article may be substantially constant throughout the length of the article. As an alternative, different portions of the aerosol-generating article may have different outer diameters.

[0188] According to any of the embodiments described herein, the present invention also relates to an aerosol-generating system comprising an aerosol-generating article according to the present invention. The aerosol-generating system further comprises an aerosol-generating device, the aerosol-generating device comprising a device chamber for receiving the aerosol-generating article and an induction heating device for inductively heating a plurality of second particles of a single susceptor element.

[0189] The aerosol-generating device may have a distal end and a mouth end opposite the distal end. The aerosol-generating device may comprise a housing. The housing of the aerosol-generating device may define a device chamber. Preferably, the device chamber is located at the mouth end of the aerosol-generating device.

[0190] The device chamber may be referred to as the heating chamber of the aerosol-generating device. The device chamber may extend between the distal end and the mouth end or proximal end. The distal end of the device chamber may be a closed end, and the mouth end or proximal end of the device chamber may be an open end. The aerosol-generating article may be inserted into the device chamber via the open end of the device chamber. The device chamber may be cylindrical in shape to conform to the same shape of the aerosol-generating article.

[0191] The expression "received within" may refer to the fact that a component or element is received completely or partially within another component or element. For example, the expression "the aerosol-generating article is received within the device chamber" means that the aerosol-generating article is received completely or partially within the device chamber of the aerosol-generating article. When the aerosol-generating article is received within the device chamber, the aerosol-generating article may abut the distal end of the device chamber. When the aerosol-generating article is received within the device chamber, the aerosol-generating article may be substantially close to the distal end of the device chamber. The distal end of the device chamber may be defined by an end wall. When the aerosol-generating article is received within the device chamber, the mouth end of the aerosol-generating article may project from the mouth end of the device chamber.

[0192] The length of the device cavity can be between 15 millimeters and 80 millimeters, or between 20 millimeters and 70 millimeters, or between 25 millimeters and 60 millimeters, or between 25 millimeters and 50 millimeters.

[0193] The length of the device cavity can be between 25 millimeters and 29 millimeters, or between 26 millimeters and 29 millimeters, or between 27 millimeters and 28 millimeters.

[0194] When the aerosol - generating article is received within the device cavity, the capsule is preferably entirely within the device cavity to optimize heating of the aerosol - forming substrate within the capsule. Accordingly, the length of the device cavity is preferably greater than the length of the capsule.

[0195] The diameter of the device cavity can be between 4 millimeters and 10 millimeters. The diameter of the device cavity can be between 5 millimeters and 9 millimeters. The diameter of the device cavity can be between 6 millimeters and 8 millimeters. The diameter of the device cavity can be between 6 millimeters and 7 millimeters.

[0196] The diameter of the device cavity can be substantially equal to or greater than the diameter of the aerosol - generating article. The diameter of the device cavity can be the same as the diameter of the aerosol - generating article to establish a tight fit with the aerosol - generating article.

[0197] The device cavity can be configured to establish a tight fit with the aerosol - generating article received within the device cavity. A tight fit can refer to a snug fit. The aerosol - generating device can include an outer peripheral wall. This outer peripheral wall can define the device cavity or the heating chamber. The outer peripheral wall defining the device cavity can be configured to engage the aerosol - generating article received within the device cavity in a tight - fit manner such that when the aerosol - generating article is received within the device, there is substantially no gap or void space between the outer peripheral wall defining the device cavity and the aerosol - generating article.

[0198] Such a tight fit can establish an air - tight fit or configuration between the device cavity and the aerosol - generating article received therein.

[0199] With the air - tight configuration, there is substantially no gap or void space for air to flow through between the outer peripheral wall defining the device cavity and the aerosol - generating article.

[0200] The tight fit with the aerosol - generating article can be established along the entire length of the device cavity or along a portion of the length of the device cavity.

[0201] An aerosol generating device may include an air flow channel extending between an inlet and an outlet of the channel. The air flow channel may be configured to establish fluid communication between the interior of the device cavity and the exterior of the aerosol generating device. The air flow channel of the aerosol generating device may be defined within the housing of the aerosol generating device to enable fluid communication between the interior of the device cavity and the exterior of the aerosol generating device. When an aerosol generating article is received within the device cavity, the air flow channel may be configured to supply an air flow into the article to deliver the generated aerosol to a user who sucks from the mouth end of the article.

[0202] The air flow channel of the aerosol generating device may be defined within or by the outer peripheral wall of the housing of the aerosol generating device. In other words, the air flow channel of the aerosol generating device may be defined within the thickness of the outer peripheral wall or by the inner surface of the outer peripheral wall, or a combination of both. The air flow channel may be partially defined by the inner surface of the outer peripheral wall and may be partially defined within the thickness of the outer peripheral wall. The inner surface of the outer peripheral wall defines the outer perimeter of the device cavity.

[0203] The air flow channel of the aerosol generating device may extend from an inlet located at the mouth end or proximal end of the aerosol generating device to an outlet remote from the mouth end of the device. The air flow channel may extend in a direction parallel to the longitudinal axis of the aerosol generating device.

[0204] An induction heating device may include an inductor coil and a power source configured to supply a high-frequency oscillating current to the inductor coil. As used herein, "high-frequency oscillating current" means an oscillating current having a frequency between about 500 kHz and about 30 MHz. The aerosol generating device may include a DC / AC inverter for converting a DC current supplied by a DC power source into an alternating current. The inductor coil may be arranged to generate a high-frequency oscillating electromagnetic field when receiving the high-frequency oscillating current from the power source. During use, the high-frequency oscillating electromagnetic field inductively heats the susceptor material of the aerosol generating article. Preferably, the inductor coil is arranged to generate a high-frequency oscillating electromagnetic field within the device cavity. The inductor coil may substantially define the device cavity. The inductor coil may at least partially extend along the length of the device cavity.

[0205] During use, the induction heating device may be controlled to heat the susceptor material within a defined operating temperature range below the maximum operating temperature. An operating temperature range between about 150 degrees Celsius and about 300 degrees Celsius within the heating chamber (or device cavity) is preferred. The operating temperature range of the heater may be between about 150 degrees Celsius and about 250 degrees Celsius.

[0206] An aerosol-generating device may include a power source. The power source may be a DC power source. In some embodiments, the power source is a battery. The power source may be a nickel-metal hydride battery, a nickel-cadmium battery, or a lithium-based battery, such as a lithium-cobalt battery, a lithium iron phosphate battery, or a lithium polymer battery. However, in some embodiments, the power source may be another form of charge storage device, such as, for example, a capacitor. The power source may need to be recharged and may have a capacity that allows sufficient energy to be stored for one or more user operations (e.g., one or more aerosol-generating experiences).

[0207] The aerosol-generating device may include a piercing device for piercing the capsule when the aerosol-generating article is inserted into the device cavity. As described above, it may be necessary to pierce the capsule in order to establish one or more air flow paths through the capsule.

[0208] The present invention also relates to a method of forming a capsule for an aerosol-generating article for generating an inhalable aerosol upon heating. The method includes providing a plurality of first particles, each first particle including an aerosol-forming substrate; and providing a plurality of second particles, each second particle including a receptor material and not including an aerosol-forming substrate. The method further includes mixing the plurality of first particles with the plurality of second particles to form a particle mixture. The method further includes providing a capsule outer wall defining an inner cavity, and inserting the particle mixture into the inner cavity to form a capsule, the capsule including the capsule outer wall and the particle mixture within the inner cavity. The capsule may include any one of the preferred or optional features of the above-described capsules.

[0209] The present invention also relates to another method of forming a capsule for an aerosol-generating article for generating an inhalable aerosol upon heating. The method includes providing a plurality of first particles, each first particle including an aerosol-forming substrate; and providing a single receptor element. The method further includes providing a capsule outer wall defining an inner cavity, and inserting the plurality of first particles and the single receptor element into the inner cavity to form a capsule, the capsule including the capsule outer wall and the plurality of first particles and the single receptor element within the inner cavity. The capsule may include any one of the preferred or optional features of the above-described capsules.

[0210] A non-exhaustive list of non-limiting examples is provided below. Any one or more features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0211] Example 1: An aerosol-generating article for generating an inhalable aerosol upon heating, the aerosol-generating article including a capsule, the capsule including:

[0212] A capsule outer wall defining an inner cavity; and

[0213] A plurality of first particles within the inner cavity, each of the first particles comprising an aerosol-forming substrate;

[0214] wherein the capsule further comprises only one of the following:

[0215] A plurality of second particles within the inner cavity, each of the second particles comprising a sensor material and not comprising an aerosol-forming substrate; or

[0216] A single sensor element within the inner cavity.

[0217] Example 2: An aerosol-generating article according to Example 1, wherein the capsule comprises the plurality of second particles.

[0218] Example 3: An aerosol-generating article according to Example 2, wherein the plurality of second particles are mixed with the plurality of first particles.

[0219] Example 4: An aerosol-generating article according to Example 2 or 3, wherein each of the first particles has an outer surface comprising a first shape, wherein each of the second particles has an outer surface comprising a second shape, and wherein a portion of the second shape is configured to engage a portion of the first shape.

[0220] Example 5: An aerosol-generating article according to Example 4, wherein a portion of the first shape is configured to receive a portion of the second shape.

[0221] Example 6: An aerosol-generating article according to Example 4 or 5, wherein a portion of the second shape is configured to receive a portion of the first shape.

[0222] Example 7: An aerosol-generating article according to any one of Examples 2 to 6, wherein each of the first particles has a first cross-sectional dimension, wherein each of the second particles has a second cross-sectional dimension, and wherein the first cross-sectional dimension and the second cross-sectional dimension are the same.

[0223] Example 8: An aerosol-generating article according to Example 7, wherein each of the first particles has a spherical shape, wherein each of the second particles has a spherical shape, wherein the first cross-sectional dimension is the diameter of each of the first particles, and wherein the second cross-sectional dimension is the diameter of each of the second particles.

[0224] Example 9: An aerosol-generating article according to any one of Examples 2 to 8, wherein each of the first particles has a first mass, each of the second particles has a second mass, and wherein the first mass and the second mass are the same.

[0225] Example 10: An aerosol-generating article according to any one of Examples 2 to 9, wherein each of the first particles has a first density, each of the second particles has a second density, and wherein the first density and the second density are the same.

[0226] Example 11: An aerosol-generating article according to any one of Examples 2 to 10, wherein the ratio of the total number of first particles to the total number of second particles is between 0.9 to 1 and 1.1 to 1.

[0227] Example 12: An aerosol-generating article according to any one of Examples 2 to 11, wherein each of the second particles has a homogeneous structure.

[0228] Example 13: An aerosol-generating article according to any one of Examples 2 to 11, wherein each of the second particles has a heterogeneous structure.

[0229] Example 14: An aerosol-generating article according to any one of Examples 2 to 11, wherein each of the second particles comprises a multi-layer sensor material.

[0230] Example 15: An aerosol-generating article according to Example 14, wherein the multi-layer sensor material comprises a first layer and a second layer, the first layer comprises a first sensor material, the second layer comprises a second sensor material, and wherein the first sensor material is different from the second sensor material.

[0231] Example 16: An aerosol-generating article according to any one of Examples 2 to 15, wherein each of the second particles has a non-uniform density.

[0232] Example 17: An aerosol-generating article according to any one of Examples 2 to 16, wherein each of the second particles comprises a shell of sensor material.

[0233] Example 18: An aerosol-generating article according to Example 17, wherein the shell of sensor material defines a void inside the shell of sensor material.

[0234] Example 19: An aerosol-generating article according to Example 18, wherein the void is filled with one of air, an inert gas, a partial vacuum, and a vacuum.

[0235] Example 20: An aerosol-generating article according to Example 18, wherein the void is filled with a non-sensor material.

[0236] Example 21: An aerosol-generating article according to Example 20, wherein the shell of the sensor material has a first density, wherein the non-sensor material has a second density, and wherein the second density is less than the first density.

[0237] Example 22: An aerosol-generating article according to Example 20 or 21, wherein the non-sensor material comprises a non-conductive foam.

[0238] Example 23: An aerosol-generating article according to any one of Examples 2 to 22, wherein each of the second particles has at least one of a size and a shape that increases the surface area of the second particle.

[0239] Example 24: An aerosol-generating article according to any one of Examples 2 to 23, wherein each of the second particles comprises a plurality of fins.

[0240] Example 25: An aerosol-generating article according to Example 24, wherein each fin is formed of the sensor material.

[0241] Example 26: An aerosol-generating article according to Example 24 or 25, wherein each of the second particles comprises a plurality of discs, and wherein each disc forms one of the plurality of fins.

[0242] Example 27: An aerosol-generating article according to Example 26, wherein the discs are arranged in a stack.

[0243] Example 28: An aerosol-generating article according to Example 27, wherein the discs are connected to each other by a central column.

[0244] Example 29: An aerosol-generating article according to Example 28, wherein the central column is formed of the sensor material.

[0245] Example 30: An aerosol-generating article according to any one of Examples 26 to 29, wherein the discs are spaced apart from each other.

[0246] Example 31: An aerosol-generating article according to any one of Examples 2 to 30, wherein each of the second particles has at least one of a size and a shape that minimizes the interlocking of the second particles with each other.

[0247] Example 32: An aerosol-generating article according to any one of Examples 2 to 31, wherein each of the second particles has at least one of a size and a shape that maximizes the contact between the second particles and the first particles.

[0248] Example 33: An aerosol-generating article according to any one of Examples 2 to 32, wherein each of the first particles has a first size, wherein each of the second particles has a second size, and wherein the second size is different from the first size.

[0249] Example 34: An aerosol-generating article according to any one of Examples 2 to 32, wherein each of the first particles has a first size, wherein each of the second particles has a second size, and wherein the second size is the same as the first size.

[0250] Example 35: An aerosol-generating article according to any one of Examples 2 to 34, wherein each of the first particles has a first shape, wherein each of the second particles has a second shape, and wherein the second shape is different from the first shape.

[0251] Example 36: An aerosol-generating article according to any one of Examples 2 to 34, wherein each of the first particles has a first shape, wherein each of the second particles has a second shape, and wherein the second shape is the same as the first shape.

[0252] Example 37: An aerosol-generating article according to any one of Examples 2 to 36, wherein each of the first particles has a first mass, wherein each of the second particles has a second mass, and wherein the difference between the first mass and the second mass is less than 10% of the first mass.

[0253] Example 38: An aerosol-generating article according to any one of Examples 2 to 37, wherein each of the first particles has a first density, wherein each of the second particles has a second density, and wherein the difference between the first density and the second density is less than 10% of the first density.

[0254] Example 39: An aerosol-generating article according to any of the preceding examples, wherein each of the first particles has a convex shape.

[0255] Example 40: An aerosol-generating article according to any of the preceding examples, wherein each of the first particles has a spherical shape, an ellipsoidal shape or an ovoid shape.

[0256] Example 41: An aerosol-generating article according to any one of Examples 2 to 40, wherein each of the second particles has a convex shape.

[0257] Example 42: An aerosol-generating article according to any one of Examples 2 to 41, wherein each of the second particles has a spherical shape, an ellipsoidal shape or an oval shape.

[0258] Example 43: An aerosol-generating article according to any one of Examples 2 to 40, wherein each of the second particles has a star-shaped polyhedron shape.

[0259] Example 44: An aerosol-generating article according to Example 1, wherein the capsule comprises the single sensor element, and wherein the single sensor element comprises a sensor material.

[0260] Example 45: An aerosol-generating article according to any one of the preceding examples, wherein the sensor material comprises at least one metal.

[0261] Example 46: An aerosol-generating article according to any one of the preceding examples, wherein the sensor material comprises at least one metal alloy.

[0262] Example 47: An aerosol-generating article according to any one of the preceding examples, wherein the sensor material comprises a foam.

[0263] Example 48: An aerosol-generating article according to any one of the preceding examples, wherein each of the first particles does not comprise a sensor material.

[0264] Example 49: An aerosol-generating article according to any one of the preceding examples, wherein the aerosol-forming substrate comprises a solid aerosol-forming substrate.

[0265] Example 50: An aerosol-generating article according to any one of the preceding examples, wherein the aerosol-forming substrate comprises at least one of tobacco and nicotine.

[0266] Example 51: An aerosol-generating article according to any one of the preceding examples, wherein the outer wall of the capsule is formed of an air-impermeable material.

[0267] Example 52: An aerosol-generating article according to any one of the preceding examples, wherein the capsule comprises at least one air inlet extending through the outer wall of the capsule and at least one air outlet extending through the outer wall of the capsule.

[0268] Example 53: An aerosol-generating article according to Example 52, wherein the at least one air inlet and the at least one air outlet are positioned to define at least one airflow path through the inner cavity between the at least one air inlet and the at least one air outlet.

[0269] Example 54: An aerosol-generating article according to Example 52 or 53, wherein each of the first particles is larger than each of the at least one air inlet and the at least one air outlet.

[0270] Example 55: An aerosol-generating article according to Example 52, 53 or 54 in combination with Example 2, wherein each of the second particles is larger than each of the at least one air inlet and the at least one air outlet.

[0271] Example 56: An aerosol-generating article according to any one of the preceding examples, wherein the inner cavity of the capsule has a volume, and wherein the first particles and the second particles or the single sensor element together occupy at least 70% of the volume of the inner cavity.

[0272] Example 57: An aerosol-generating article according to any one of the preceding claims, further comprising a hollow tubular element, wherein the capsule is positioned within the hollow tubular element.

[0273] Example 58: An aerosol-generating article according to Example 57, wherein the capsule is positioned at the upstream end of the hollow tubular element.

[0274] Example 59: An aerosol-generating article according to Example 57 or 58, wherein the hollow tubular element is formed of at least one of paper and cardboard.

[0275] Example 60: An aerosol-generating article according to Example 57, 58 or 59, wherein the capsule is retained within the hollow tubular element by an interference fit.

[0276] Example 61: An aerosol-generating article according to any one of Examples 57 to 60, further comprising a filter element positioned downstream of the hollow tubular element.

[0277] Example 62: An aerosol-generating article according to Example 61, wherein the filter element is positioned adjacent to the downstream end of the hollow tubular element.

[0278] Example 63: An aerosol-generating article according to Example 61 or 62, wherein the filter element is positioned at the downstream end of the aerosol-generating article.

[0279] Example 64: An aerosol-generating article according to Example 61, 62 or 63, wherein the filter element is spaced from the capsule to define a cavity between the capsule and the filter element.

[0280] Example 65: An aerosol-generating system, the aerosol-generating system comprising:

[0281] An aerosol-generating article according to any one of the preceding examples; and

[0282] An aerosol-generating device, the aerosol-generating device comprising:

[0283] a device cavity for receiving at least a portion of the aerosol-generating article; and

[0284] an induction heating device for inductively heating the plurality of second particles or the single susceptor element.

[0285] Example 66: A method of forming a capsule for an aerosol-generating article, the aerosol-generating article being adapted to generate an inhalable aerosol upon heating, the method comprising:

[0286] providing a plurality of first particles, each first particle comprising an aerosol-forming substrate;

[0287] providing a plurality of second particles, each second particle comprising a susceptor material and not comprising an aerosol-forming substrate;

[0288] mixing the plurality of first particles with the plurality of second particles to form a particle mixture;

[0289] providing a capsule outer wall defining an inner cavity; and

[0290] inserting the particle mixture into the inner cavity to form a capsule, the capsule comprising the capsule outer wall and the particle mixture within the inner cavity.

[0291] Example 67: A method of forming a capsule for an aerosol-generating article, the aerosol-generating article being adapted to generate an inhalable aerosol upon heating, the method comprising:

[0292] providing a plurality of first particles, each first particle comprising an aerosol-forming substrate;

[0293] providing a single susceptor element;

[0294] providing a capsule outer wall defining an inner cavity; and

[0295] inserting the plurality of first particles and the single susceptor element into the inner cavity to form a capsule, the capsule comprising the capsule outer wall and the plurality of first particles and the single susceptor element within the inner cavity.

[0296] Example 68: The method according to Example 66 or Example 67, wherein the capsule is a capsule comprising the features of any one of Examples 1 to 64. Description of the Drawings

[0297] The present invention will be further described with reference to the accompanying drawings, in which:

[0298] Figure 1 a cross-sectional view of an aerosol-generating article according to an embodiment of the present invention is shown;

[0299] Figure 2 shows a Figure 1 cross-sectional view of a capsule of an aerosol-generating article;

[0300] Figure 3 shows a cross-sectional view of an aerosol-generating system that includes an aerosol-generating device and an Figure 1 aerosol-generating article received within the aerosol-generating device;

[0301] Figure 4 shows a Figure 2 cross-sectional view of an alternative second particle of a capsule;

[0302] Figure 5 shows a Figure 4 perspective view of a second particle;

[0303] Figure 6 shows a Figure 2 perspective view of another alternative second particle of a capsule;

[0304] Figure 7 shows a Figure 6 perspective view of a second particle that nests multiple first particles, each first particle having a spherical shape; and

[0305] Figure 8 shows a Figure 1 cross-sectional view of an alternative capsule of the aerosol-generating article in Detailed Description

[0306] Figure 1 Shows an aerosol-generating article 10 that includes a hollow tubular element 12 and a capsule 14 mounted at an upstream end of the hollow tubular element 12. The aerosol-generating article 10 extends from an upstream end or distal end 16 to a downstream end or mouth end 18. The upstream end 16 coincides with the upstream end of the capsule 14. The downstream end 18 coincides with the downstream end of the hollow tubular element 12.

[0307] The aerosol-generating article 10 has a total length of approximately 45 millimeters and an outer diameter of approximately 7.2 mm.

[0308] The hollow tubular element 12 is formed of a cylindrical cardboard tube having a wall thickness of approximately 0.25 millimeters. The hollow tubular element 12 defines an internal channel. The hollow tubular element 12 has a length of approximately 45 millimeters, an outer diameter of approximately 7.2 millimeters, and an inner diameter of approximately 6.7 millimeters. The capsule 14 is mounted within the internal channel of the hollow tubular element 12 at the upstream end.

[0309] Figure 2 Shows a more detailed cross-sectional view of the capsule 14 of the aerosol-generating article 10 suitable for Figure 1 the aerosol-generating article 10.

[0310] The capsule 14 is a two-part capsule formed from an air-impermeable polymer such as HPMC. The capsule 14 has an elongate capsule (spherical-cylindrical) shape with a circular cross-section. The capsule includes a capsule outer wall 20 defining an inner cavity 22 that contains a plurality of first particles 24 and a plurality of second particles 25 mixed with the plurality of first particles 24. Each of the first particles 24 includes an aerosol-forming substrate, which is a solid aerosol-forming substrate including nicotine. Each of the second particles 25 includes a sensor material, which includes stainless steel. The capsule outer wall 20 is defined by a cylindrical wall 26 and opposing hemispherical end walls 28, 29, which are integrally formed with the cylindrical wall 26. The capsule 14 has a length of approximately 20 millimeters and an outer diameter of approximately 6.7 millimeters. Thus, the outer diameter of the capsule 14 is similar to the inner diameter of the hollow tubular element 12 such that the capsule is held within the hollow tubular element 12 by a friction fit.

[0311] The downstream filter segment 50 is spaced from the capsule 14 to define a cavity 52 within the hollow tubular element 12. The cavity 52 has a length of approximately 25 millimeters. The downstream filter segment 50 extends to the downstream end of the hollow tubular element 12 such that the downstream end of the downstream filter segment 50 substantially coincides with the downstream end 18 of the aerosol-generating article 10.

[0312] The downstream filter segment 50 has a length of approximately 10 millimeters and includes a low-density cellulose acetate filter segment. The RTD of the downstream filter segment 50 is approximately 10mmH 2 O.

[0313] The capsule 14 is mounted within the hollow tubular element 12 such that approximately 30% of the capsule 14 extends beyond the upstream end of the hollow tubular element 12. Thus, the capsule 14 projects from the upstream end of the hollow tubular element 12, and the upstream end of the capsule 14 defines the upstream end 16 of the aerosol-generating article 10.

[0314] The capsule has an internal volume of approximately 600 cubic millimeters and contains approximately 200 milligrams of aerosol-forming substrate. Thus, the capsule contains approximately 0.33 milligrams of aerosol-forming substrate per cubic millimeter of the inner cavity 22.

[0315] The capsule 14 includes a plurality of air outlets 30, each air outlet in the form of a hole extending through the capsule outer wall 20 and each having a diameter of approximately 0.5 millimeters. The plurality of air inlets 30 are spaced apart in a circular configuration on the upstream end wall 28 of the capsule 14.

[0316] The capsule 14 further includes a plurality of air outlets 32, each air outlet being in the form of a hole extending through the outer wall 20 of the capsule and each having a diameter of approximately 0.5 millimeters. The plurality of air outlets 32 are spaced apart in a circular configuration on the downstream end wall 29 of the capsule 14.

[0317] The protrusion of the capsule 14 from the upstream end of the hollow tubular element 12 means that the air inlet 30 is located outside the hollow tubular element 12.

[0318] The air inlet 30 and the air outlets 32 are arranged to be substantially symmetric with each other at opposite ends of the capsule 14.

[0319] The arrangement of the air inlet 30 and the air outlets 32 defines a plurality of air flow paths through the lumen 22 of the capsule 14 such that during heating, ambient air can be drawn through the capsule 14 and contacted with the first particles 24 of the solid first aerosol-forming substrate. The aerosol generated by the first particles 24 of the solid first aerosol-forming substrate during heating will be withdrawn from the capsule 14 together with the ambient air, pass through the air outlets 32 and be drawn along the hollow tubular element 12 to the downstream end 18 of the aerosol-generating article 10.

[0320] Each of the first particles 24 of the solid first aerosol-forming substrate contained within the capsule 14 is in the shape of an ellipsoid having a major axis of 0.8 millimeters. Those skilled in the art will appreciate that other shapes and sizes of the first particles 24 can be used. For example, in an alternative embodiment, each of the first particles is in a substantially spherical shape having a diameter of 0.8 millimeters. Each of the first particles 24 of the aerosol-forming substrate is formed from a gel composition having the following composition:

[0321] Component wt% Glycerol 76.8 Alginate 3.8 Nicotine 2.4 Levulinic acid 2.1 Water 14.4 Calcium chloride 0.5

[0322] Figure 3Figure 100 shows an aerosol-generating system 100 according to an embodiment of the present invention. The aerosol-generating system 100 includes an aerosol-generating article 10 as described above. The aerosol-generating system 100 also includes an aerosol-generating device 102. The aerosol-generating device 102 includes a device housing 145. The device housing 145 defines a device chamber 142 for receiving an upstream end of the aerosol-generating article 10. The device chamber 142 has an inner diameter that substantially corresponds to the outer diameter of the aerosol-generating article 10. The aerosol-generating device 102 also includes an inductive heating device 141 that includes an inductor surrounding a portion of the device chamber 142. When the aerosol-generating article 10 is received within the device chamber 142, the capsule 14 is positioned within the inductor coil. During use, a controller (not shown) supplies an alternating current from a power source (not shown) to the inductor coil such that the inductor coil generates a changing magnetic field. The changing magnetic field inductively heats a susceptor material of the second particles 25, which in turn heats the first particles 24 to generate an aerosol from the solid aerosol-forming substrate. The device housing 145 defines a plurality of device air inlets 150 that communicate with the device chamber 142. Thus, the aerosol-generating system 100 includes an airflow path that extends from the device air inlets 150, through the capsule 14 via the capsule air inlet 30 and the capsule air outlet 32, and through the hollow tubular element 12 and the downstream filter section 50 to deliver the aerosol to the user.

[0323] Figure 4 and Figure 5 Figure 10 shows an alternative form of the second particles of the capsule 14. In particular, Figure 4 and Figure 5 Figure 11 shows second particles 225 that include a plurality of spaced-apart discs 227, each disc 227 being formed from a susceptor material that includes stainless steel. The discs 227 are connected to each other by a central post 229, which is preferably also formed from a susceptor material such as stainless steel. The stacking of the spaced-apart discs 227 significantly increases the surface area of the second particles 225 compared to spherical particles of the same size. The increased surface area increases the rate of heat emission from the second particles 225, which provides more efficient heating of the first particles 24.

[0324] Figure 6 and Figure 7 Figure 12 shows another alternative form of the second particles of the capsule 14. In particular, Figure 6 and Figure 7 Figure 13 shows second particles 325 having a star-shaped polyhedron shape formed from a susceptor material that includes stainless steel. As Figure 7, which shows a second particle 325 and a plurality of first particles 24 each having a spherical shape, the star-shaped polyhedron shape of the second particle 325 facilitates nesting of the second particle 325 between the plurality of first particles 24. The increased nesting facilitates mixing of the second particles 325 with the first particles 24 in the capsule 14, and facilitates heat transfer from the second particles 325 to the first particles 24.

[0325] Figure 8 Shown for Figure 1 A cross-sectional view of an alternative capsule 414 of an aerosol-generating article 10 is shown. Figure 8 The capsule 414 is similar to Figure 2 The present invention relates to a capsule 14 of the present invention, and like reference numerals represent like parts. The capsule 414 includes a single susceptor element 425 formed of a susceptor material including stainless steel instead of the plurality of second particles 25. The single susceptor element 425 is strip-shaped and extends along almost the entire length of the inner cavity 22 of the capsule 414. The single susceptor element 425 is surrounded by the plurality of first particles 24 so that during use, heat is transferred from the single susceptor element 425 to the first particles 24.

Claims

1. An aerosol - generating article for generating an inhalable aerosol upon heating, the aerosol - generating article comprising a capsule, the capsule comprising: a capsule outer wall defining an inner cavity; and a plurality of first particles within the inner cavity, each of the first particles comprising an aerosol - forming matrix; and a plurality of second particles within the inner cavity, each of the second particles comprising a sensor material and not comprising an aerosol - forming matrix; wherein the capsule further comprises at least one of the following: Each of the first particles has a first cross - sectional dimension, and each of the second particles has a second cross - sectional dimension, wherein the first cross - sectional dimension and the second cross - sectional dimension are the same, wherein each of the first particles has a spherical shape, wherein each of the second particles has a spherical shape, wherein the first cross - sectional dimension is the diameter of each of the first particles, and wherein the second cross - sectional dimension is the diameter of each of the second particles; Each of the first particles has a first mass, and each of the second particles has a second mass, wherein the first mass and the second mass are the same; Each of the first particles has a first density, and each of the second particles has a second density, wherein the first density and the second density are the same; The ratio of the total number of first particles to the total number of second particles is between 0.2 to 1 and 5 to 1; or The ratio of the total mass of first particles to the total mass of second particles is between 0.2 to 1 and 5 to 1.

2. The aerosol - generating article according to claim 1, wherein the plurality of second particles are mixed with the plurality of first particles.

3. The aerosol - generating article according to claim 1 or 2, wherein each of the first particles has an outer surface including a first shape, wherein each of the second particles has an outer surface including a second shape, and wherein a part of the second shape is configured to engage with a part of the first shape.

4. The aerosol - generating article according to claim 3, wherein a part of the first shape is configured to receive a part of the second shape.

5. The aerosol - generating article according to claim 3 or 4, wherein a part of the second shape is configured to receive a part of the first shape.

6. The aerosol - generating article according to any one of the preceding claims, wherein each of the first particles does not comprise a sensor material.

7. An aerosol - generating system, the aerosol - generating system comprising: an aerosol - generating article according to any one of the preceding claims; and an aerosol - generating device, the aerosol - generating device comprising: a device cavity for receiving at least a part of the aerosol - generating article; and an induction heating device for inductively heating the plurality of second particles or a single sensor element.

8. A method of forming a capsule for an aerosol-generating article, the aerosol-generating article being adapted to generate an inhalable aerosol upon heating, the method comprising: providing a plurality of first particles, each first particle comprising an aerosol-forming substrate; providing a plurality of second particles, each second particle comprising a sensor material and not comprising an aerosol-forming substrate; mixing the plurality of first particles with the plurality of second particles to form a particle mixture; providing a capsule outer wall defining an inner cavity; and inserting the particle mixture into the inner cavity to form a capsule, the capsule comprising the capsule outer wall and the particle mixture within the inner cavity, the capsule further comprising at least one of the following: each first particle of the first particles has a first cross-sectional dimension, and each second particle of the second particles has a second cross-sectional dimension, wherein the first cross-sectional dimension and the second cross-sectional dimension are the same, wherein each first particle of the first particles has a spherical shape, wherein each second particle of the second particles has a spherical shape, wherein the first cross-sectional dimension is the diameter of each first particle of the first particles, and wherein the second cross-sectional dimension is the diameter of each second particle of the second particles; each first particle of the first particles has a first mass, and each second particle of the second particles has a second mass, wherein the first mass and the second mass are the same; each first particle of the first particles has a first density, and each second particle of the second particles has a second density, wherein the first density and the second density are the same; the ratio of the total number of first particles to the total number of second particles is between 0.2 to 1 and 5 to 1; or the ratio of the total mass of first particles to the total mass of second particles is between 0.2 to 1 and 5 to 1.

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