Patent Publication Number: US-2022211106-A1

Title: Capsules with integrated mouthpieces, heat-not-burn (hnb) aerosol-generating devices, and methods of generating an aerosol

Description:
BACKGROUND 
     Field 
     The present disclosure relates to capsules, heat-not-burn (HNB) aerosol-generating devices, and methods of generating an aerosol without involving a substantial pyrolysis of the aerosol-forming substrate. 
     Description of Related Art 
     Some electronic devices are configured to heat a plant material to a temperature that is sufficient to release constituents of the plant material while keeping the temperature below a combustion point of the plant material so as to avoid any substantial pyrolysis of the plant material. Such devices may be referred to as aerosol-generating devices (e.g., heat-not-burn aerosol-generating devices), and the plant material heated may be tobacco. In some instances, the plant material may be introduced directly into a heating chamber of an aerosol-generating device. In other instances, the plant material may be pre-packaged in individual containers to facilitate insertion and removal from an aerosol-generating device. 
     SUMMARY 
     At least one embodiment relates to a capsule for a heat-not-burn (HNB) aerosol-generating device. In an example embodiment, the capsule may include a base portion, a first cover, a second cover, an aerosol-forming substrate, and a heater. The base portion includes an engagement assembly. The first cover is engaged with the base portion via the engagement assembly. The first cover includes a first interior surface and a first exterior surface. The first interior surface defines a first recess. The second cover is engaged with the base portion and the first cover via the engagement assembly. The second cover includes a second interior surface and a second exterior surface. The second interior surface defines a second recess. The first cover is aligned with the second cover such that the first recess and the second recess collectively form a chamber. The aerosol-forming substrate is within the chamber. The heater is configured to heat the aerosol-forming substrate to generate an aerosol. The heater includes a first end section, an intermediate section, and a second end section. The heater extends from the base portion such that the intermediate section is in the chamber. 
     At least one embodiment relates to a heat-not-burn (HNB) aerosol-generating device. In an example embodiment, the aerosol-generating device may include a capsule and a device body. The capsule includes a housing containing an aerosol-forming substrate and a heater configured to heat the aerosol-forming substrate. The housing includes a base portion, a first cover, and a second cover. The first cover and the second cover jointly define therebetween a chamber, an aerosol channel, and an aerosol outlet. The aerosol-forming substrate is disposed in the chamber. The heater is supported by the base portion and extends into the chamber. The device body is configured to connect to the capsule. The device body includes a power source configured to supply an electric current to the heater. 
     At least one embodiment relates to a method of generating an aerosol. In an example embodiment, the method may include supplying an electric current to a capsule including a housing containing an aerosol-forming substrate and a heater such that the heater undergoes resistive heating. The housing includes a base portion, a first cover, and a second cover. The first cover and the second cover jointly define therebetween a chamber, an aerosol channel, and an aerosol outlet. The aerosol-forming substrate is disposed in the chamber. The heater is supported by the base portion and extends into the chamber. The method may optionally include drawing the aerosol generated by the resistive heating from the chamber and through the aerosol channel and the aerosol outlet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various features and advantages of the non-limiting embodiments herein may become more apparent upon review of the detailed description in conjunction with the accompanying drawings. The accompanying drawings are merely provided for illustrative purposes and should not be interpreted to limit the scope of the claims. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. For purposes of clarity, various dimensions of the drawings may have been exaggerated. 
         FIG. 1  is a first perspective view of a capsule for an aerosol-generating device according to an example embodiment. 
         FIG. 2  is a second perspective view of the capsule of  FIG. 1 . 
         FIG. 3  is a partially exploded view of the capsule of  FIG. 1 . 
         FIG. 4  is a partially exploded view of the capsule of  FIG. 2 . 
         FIG. 5  is a further exploded view of the capsule of  FIG. 3 . 
         FIG. 6  is a further exploded view of the capsule of  FIG. 4 . 
         FIG. 7  is a cross-sectional view of the capsule of  FIG. 1 . 
         FIG. 8  is a first perspective view of another capsule for an aerosol-generating device according to an example embodiment. 
         FIG. 9  is a second perspective view of the capsule of  FIG. 8 . 
         FIG. 10  is a partially exploded view of the capsule of  FIG. 8 . 
         FIG. 11  is a partially exploded view of the capsule of  FIG. 9 . 
         FIG. 12  is a cross-sectional view of the capsule of  FIG. 8 . 
         FIG. 13  is a first perspective view of another capsule for an aerosol-generating device according to an example embodiment. 
         FIG. 14  is a second perspective view of the capsule of  FIG. 13 . 
         FIG. 15  is a partially exploded view of the capsule of  FIG. 13 . 
         FIG. 16  is a partially exploded view of the capsule of  FIG. 14 . 
         FIG. 17  is a cross-sectional view of the capsule of  FIG. 13 . 
         FIG. 18  is a front view of an aerosol-generating device according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Some detailed example embodiments are disclosed herein. However, specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments. Example embodiments may, however, be embodied in many alternate forms and should not be construed as limited to only the example embodiments set forth herein. 
     Accordingly, while example embodiments are capable of various modifications and alternative forms, example embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit example embodiments to the particular forms disclosed, but to the contrary, example embodiments are to cover all modifications, equivalents, and alternatives thereof. Like numbers refer to like elements throughout the description of the figures. 
     It should be understood that when an element or layer is referred to as being “on,” “connected to,” “coupled to,” “attached to,” “adjacent to,” or “covering” another element or layer, it may be directly on, connected to, coupled to, attached to, adjacent to or covering the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. Like numbers refer to like elements throughout the specification. As used herein, the term “and/or” includes any and all combinations or sub-combinations of one or more of the associated listed items. 
     It should be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, regions, layers and/or sections, these elements, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, region, layer, or section from another region, layer, or section. Thus, a first element, region, layer, or section discussed below could be termed a second element, region, layer, or section without departing from the teachings of example embodiments. 
     Spatially relative terms (e.g., “beneath,” “below,” “lower,” “above,” “upper,” and the like) may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It should be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the term “below” may encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The terminology used herein is for the purpose of describing various example embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes,” “including,” “comprises,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, and/or elements, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or groups thereof. 
     When the terms “about” or “substantially” are used in this specification in connection with a numerical value, it is intended that the associated numerical value includes a manufacturing or operational tolerance (e.g., ±10%) around the stated numerical value. Moreover, when the terms “generally” or “substantially” are used in connection with geometric shapes, it is intended that precision of the geometric shape is not required but that latitude for the shape is within the scope of the disclosure. Furthermore, regardless of whether numerical values or shapes are modified as “about,” “generally,” or “substantially,” it will be understood that these values and shapes should be construed as including a manufacturing or operational tolerance (e.g., ±10%) around the stated numerical values or shapes. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, including those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     The processing circuitry may be hardware including logic circuits; a hardware/software combination such as a processor executing software; or a combination thereof. For example, the processing circuitry more specifically may include, but is not limited to, a central processing unit (CPU), an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a System-on-Chip (SoC), a programmable logic unit, a microprocessor, application-specific integrated circuit (ASIC), etc. 
       FIG. 1  is a first perspective view of a capsule for an aerosol-generating device according to an example embodiment.  FIG. 2  is a second perspective view of the capsule of  FIG. 1 . Referring to  FIGS. 1-2 , a capsule  100  includes a housing configured to hold an aerosol-forming substrate and to accommodate a heater configured to heat the aerosol-forming substrate to generate an aerosol. The housing of the capsule  100  includes a base portion  130 , a first cover  110 , and a second cover  120 . The base portion  130  includes an engagement assembly  136  configured to facilitate a connection with the first cover  110  and the second cover  120 . Once connected to the base portion  130 , the first cover  110  and the second cover  120  are configured to be received by an end cap  170 . The end cap  170  defines at least one aerosol outlet  174 . As a result, the end cap  170  may be regarded as a mouthpiece that is integrated with the housing to produce a capsule  100  that is of a 4-piece construction. 
     Additionally, when connected, the base portion  130  and the first cover  110  define a first air inlet  152  therebetween. Similarly, the base portion  130  and the second cover  120 , when connected, define a second air inlet  154  therebetween. The first air inlet  152  and the second air inlet  154  are in fluidic communication with the aerosol outlets  174 . As a result, air drawn into the first air inlet  152  and the second air inlet  154  will flow through the capsule  100  to the aerosol outlets  174 . A heater is configured to extend through the base portion  130  such that the first end section  142  and the second end section  146  are visible while the intermediate section of the heater is hidden from view when the capsule  100  is assembled. The heater will be discussed in further detail in connection with subsequent drawings. 
       FIG. 3  is a partially exploded view of the capsule of  FIG. 1 .  FIG. 4  is a partially exploded view of the capsule of  FIG. 2 . Referring to  FIGS. 3-4 , the first cover  110  and the second cover  120  are configured to engage with each other and with the base portion  130  such that their adjacent surfaces are substantially flush. For instance, when engaged, the main external surface of the first cover  110  may be flush with the front surface of the base portion  130  (e.g.,  FIG. 3 ). Similarly, in another instance, the main external surface of the second cover  120  may be flush with the rear surface of the base portion  130  (e.g.,  FIG. 4 ). Additionally, in yet another instance, the opposing side surfaces of the base portion  130  may be flush with the adjoining side surfaces of the first cover  110  and the second cover  120 . Furthermore, in yet another instance, the downstream end surface of the first cover  110  may be flush with the downstream end surface of the second cover  120 . 
     When the first cover  110 , the second cover  120 , and the base portion  130  are coupled together, the resulting structure (e.g., housing) may have a form resembling a cuboid with a front face, an opposing rear face, a first side face, an opposing second side face, an upstream end face, and an opposing downstream end face. As used herein, “upstream” (and, conversely, “downstream”) is in relation to a flow of the aerosol, and “proximal” (and, conversely, “distal”) is in relation to an adult operator of the device during aerosol generation. With a form resembling a cuboid, the resulting structure (from the coupling of the first cover  110 , the second cover  120 , and the base portion  130 ) may have a rectangular cross-section. Alternatively, in other instances, the cuboid form of the resulting structure may have a square cross-section. However, it should be understood that example embodiments are not limited thereto. For instance, in lieu of a cuboid form, the resulting structure may have a form resembling a cylinder (e.g., elliptic cylinder, circular cylinder). For an elliptic cylinder, the resulting structure may have an elliptical cross-section. On the other hand, for a circular cylinder, the resulting structure may have a circular cross-section. 
     With regard to the cuboid form resulting from the coupling of the first cover  110 , the second cover  120 , and the base portion  130  as shown in the drawings, the main external surface of the first cover  110  and the front surface of the base portion  130  may be jointly regarded as the front face (e.g., which defines the first air inlet  152 ). Similarly, the main external surface of the second cover  120  and the rear surface of the base portion  130  may be jointly regarded as the opposing rear face (e.g., which defines the second air inlet  154 ). Additionally, the opposing side surfaces of the base portion  130  and the corresponding side surfaces of the first cover  110  and the second cover  120  may be jointly regarded as the first side face and the opposing second side face of the housing. Moreover, the underside or bottom of the base portion  130  may be regarded as the upstream end face (e.g., from which the first end section  142  and the second end section  146  of the heater extend). Furthermore, the downstream end surface of the first cover  110  and the corresponding downstream end surface of the second cover  120  may be jointly regarded as the downstream end face of the housing. 
     As shown in  FIG. 3 , the downstream end face of the housing defines a passageway  166 . The passageway  166  is in fluidic communication with the first air inlet  152  and the second air inlet  154 . As a result, when the capsule  100  is fully assembled, the air drawn into the first air inlet  152  and the second air inlet  154  will flow through the passageway  166  en route to the aerosol outlets  174 . In an example embodiment, the first air inlet  152 , the second air inlet  154 , and the passageway  166  are dimensioned so as to be small enough to retain the aerosol-forming substrate within the housing while large enough to permit an adequate inflow of air via the first air inlet  152  and the second air inlet  154  and to permit an adequate outflow of aerosol via the passageway  166 . 
     Although the drawings illustrate the end cap  170  as defining four aerosol outlets  174 , it should be understood that example embodiments are not limited thereto. For instance, the end cap  170  may define less than four (e.g., 1-3) aerosol outlets  174 . In another instance, the end cap  170  may define more than four (e.g., 5-8) aerosol outlets  174 . The form of the end cap  170  may correspond to the form of the housing formed by the first cover  110 , the second cover  120 , and the base portion  130  (e.g., cuboid form for both the end cap  170  and the housing). Alternatively, the form of the end cap  170  may differ from the form of the housing formed by the first cover  110 , the second cover  120 , and the base portion  130  (e.g., cuboid form for the end cap  170  and cylindrical form for the housing or vice versa). Additionally, the aerosol outlets  174  may be arranged in a linear/sequential manner, in a radial manner, or in an array of rows and columns depending on the number of aerosol outlets  174  as well as the form and available space of the end cap  170 . Furthermore, the shape of each of the aerosol outlets  174  may be circular, elongated (e.g., elliptical), polygonal (e.g., rounded rectangular), or of another suitable shape. 
     As shown in  FIG. 4 , the end cap  170  defines a cavity  172  configured to receive the first cover  110  and the second cover  120  of the housing during the assembly of the capsule  100 . In an example embodiment, when the capsule  100  is assembled, the main external surfaces of the first cover  110  and the second cover  120  will interface with the corresponding main internal surfaces of the end cap  170 . In lieu of (or in addition to) such an interfacial engagement, the external side surfaces of the first cover  110  and the second cover  120  may interface with the corresponding internal side surfaces of the end cap  170 . Such interfacial engagements may be via an interference fit (which may also be referred to as a press fit or friction fit). However, it should be understood that other attachment techniques may also be utilized. For instance, the attachment technique may include an adhesive (e.g., tape, glue) that has been deemed food-safe or otherwise acceptable by a regulatory authority. In another instance, the attachment technique may involve ultrasonic welding. 
       FIG. 5  is a further exploded view of the capsule of  FIG. 3 .  FIG. 6  is a further exploded view of the capsule of  FIG. 4 . Referring to  FIGS. 5-6 , the first cover  110  defines a first notch  112 , a first recess  114 , and a first downstream rim  116 . Similarly, the second cover  120  defines a second notch  122 , a second recess  124 , and a second downstream rim  126 . In some instances, the first cover  110  and the second cover  120  may be identical parts. In such instances, orienting the first cover  110  and the second cover  120  to face each other for mating with the base portion  130  will result in a complementary arrangement. As a result, one part may be used interchangeably as the first cover  110  or the second cover  120 , thus simplifying the method of manufacturing. 
     In an example embodiment, the first notch  112  may be defined as a pair of notches at the upstream corners of the first cover  110 , wherein each notch may be adjacent to/exposed by the upstream end surface of the first cover  110  and also adjacent to/exposed by a side surface of the first cover  110  (e.g.,  FIG. 6 ). Likewise, the second notch  122  may be defined as a pair of notches at the upstream corners of the second cover  120 , wherein each notch may be adjacent to/exposed by the upstream end surface of the second cover  120  and also adjacent to/exposed by a side surface of the second cover  120  (e.g.,  FIG. 5 ). During assembly, the first notch  112  and the second notch  122  collectively form a T-shaped notch configured to mate with the engagement assembly  136  when the first cover  110  and the second cover  120  are coupled with the base portion  130 . 
     Additionally, the first recess  114  of the first cover  110  and the second recess  124  of the second cover  120  collectively form a chamber (e.g., chamber  164  in  FIG. 7 ) configured to accommodate the intermediate section  144  of the heater  140  when the first cover  110  and the second cover  120  are coupled with the base portion  130 . As illustrated in  FIGS. 5-6 , a first aerosol-forming substrate  160   a  and a second aerosol-forming substrate  160   b  may also be accommodated within the chamber so as to be in thermal contact with the intermediate section  144  of the heater  140  when the capsule  100  is assembled. 
     In one instance, each of the first aerosol-forming substrate  160   a  and the second aerosol-forming substrate  160   b  may be in a consolidated form (e.g., sheet, pallet, tablet) that is configured to maintain its shape so as to allow the first aerosol-forming substrate  160   a  and the second aerosol-forming substrate  160   b  to be placed in a unified manner within the first recess  114  of the first cover  110  and the second recess  124  of the second cover  120 , respectively. In such an instance, the first aerosol-forming substrate  160   a  may be disposed on one side of the intermediate section  144  of the heater  140  (e.g., side facing the first cover  110 ), while the second aerosol-forming substrate  160   b  may be disposed on the other side of the intermediate section  144  of the heater  140  (e.g., side facing the second cover  120 ) so as to substantially fill the first recess  114  of the first cover  110  and the second recess  124  of the second cover  120 , respectively, thereby sandwiching/embedding the intermediate section  144  of the heater  140  in between. Alternatively, one or both of the first aerosol-forming substrate  160   a  and the second aerosol-forming substrate  160   b  may be in a loose form (e.g., particles, fibers, grounds, fragments, shreds) that does not have a set shape but rather is configured to take on the shape of the first recess  114  of the first cover  110  and/or the second recess  124  of the second cover  120  when introduced. 
     As discussed herein, an aerosol-forming substrate is a material or combination of materials that may yield an aerosol. An aerosol relates to the matter generated or output by the devices disclosed, claimed, and equivalents thereof. The material may include a compound (e.g., nicotine, cannabinoid), wherein an aerosol including the compound is produced when the material is heated. The heating may be below the combustion temperature so as to produce an aerosol without involving a substantial pyrolysis of the aerosol-forming substrate or the substantial generation of combustion byproducts (if any). Thus, in an example embodiment, pyrolysis does not occur during the heating and resulting production of aerosol. In other instances, there may be some pyrolysis and combustion byproducts, but the extent may be considered relatively minor and/or merely incidental. 
     The aerosol-forming substrate may be a fibrous material. For instance, the fibrous material may be a botanical material. The fibrous material is configured to release a compound when heated. The compound may be a naturally occurring constituent of the fibrous material. For instance, the fibrous material may be plant material such as tobacco, and the compound released may be nicotine. The term “tobacco” includes any tobacco plant material including tobacco leaf, tobacco plug, reconstituted tobacco, compressed tobacco, shaped tobacco, or powder tobacco, and combinations thereof from one or more species of tobacco plants, such as  Nicotiana rustica  and  Nicotiana tabacum.    
     In some example embodiments, the tobacco material may include material from any member of the genus  Nicotiana . In addition, the tobacco material may include a blend of two or more different tobacco varieties. Examples of suitable types of tobacco materials that may be used include, but are not limited to, flue-cured tobacco, Burley tobacco, Dark tobacco, Maryland tobacco, Oriental tobacco, rare tobacco, specialty tobacco, blends thereof, and the like. The tobacco material may be provided in any suitable form, including, but not limited to, tobacco lamina, processed tobacco materials, such as volume expanded or puffed tobacco, processed tobacco stems, such as cut-rolled or cut-puffed stems, reconstituted tobacco materials, blends thereof, and the like. In some example embodiments, the tobacco material is in the form of a substantially dry tobacco mass. Furthermore, in some instances, the tobacco material may be mixed and/or combined with at least one of propylene glycol, glycerin, sub-combinations thereof, or combinations thereof. 
     The compound may also be a naturally occurring constituent of a medicinal plant that has a medically-accepted therapeutic effect. For instance, the medicinal plant may be a  cannabis  plant, and the compound may be a cannabinoid. Cannabinoids interact with receptors in the body to produce a wide range of effects. As a result, cannabinoids have been used for a variety of medicinal purposes (e.g., treatment of pain, nausea, epilepsy, psychiatric disorders). The fibrous material may include the leaf and/or flower material from one or more species of  cannabis  plants such as  Cannabis sativa, Cannabis indica , and  Cannabis ruderalis . In some instances, the fibrous material is a mixture of 60-80% (e.g., 70%)  Cannabis sativa  and 20-40% (e.g., 30%)  Cannabis  indica. 
     Examples of cannabinoids include tetrahydrocannabinolic acid (THCA), tetrahydrocannabinol (THC), cannabidiolic acid (CBDA), cannabidiol (CBD), cannabinol (CBN), cannabicyclol (CBL), cannabichromene (CBC), and cannabigerol (CBG). Tetrahydrocannabinolic acid (THCA) is a precursor of tetrahydrocannabinol (THC), while cannabidiolic acid (CBDA) is precursor of cannabidiol (CBD). Tetrahydrocannabinolic acid (THCA) and cannabidiolic acid (CBDA) may be converted to tetrahydrocannabinol (THC) and cannabidiol (CBD), respectively, via heating. In an example embodiment, heat from a heater (e.g., heater  140  shown in  FIG. 5 ) may cause decarboxylation so as to convert the tetrahydrocannabinolic acid (THCA) in the capsule  100  to tetrahydrocannabinol (THC), and/or to convert the cannabidiolic acid (CBDA) in the capsule  100  to cannabidiol (CBD). 
     In instances where both tetrahydrocannabinolic acid (THCA) and tetrahydrocannabinol (THC) are present in the capsule  100 , the decarboxylation and resulting conversion will cause a decrease in tetrahydrocannabinolic acid (THCA) and an increase in tetrahydrocannabinol (THC). At least 50% (e.g., at least 87%) of the tetrahydrocannabinolic acid (THCA) may be converted to tetrahydrocannabinol (THC) during the heating of the capsule  100 . Similarly, in instances where both cannabidiolic acid (CBDA) and cannabidiol (CBD) are present in the capsule  100 , the decarboxylation and resulting conversion will cause a decrease in cannabidiolic acid (CBDA) and an increase in cannabidiol (CBD). At least 50% (e.g., at least 87%) of the cannabidiolic acid (CBDA) may be converted to cannabidiol (CBD) during the heating of the capsule  100 . 
     Furthermore, the compound may be or may additionally include a non-naturally occurring additive that is subsequently introduced into the fibrous material. In one instance, the fibrous material may include a synthetic material. In another instance, the fibrous material may include a natural material such as a cellulose material (e.g., non-tobacco and/or non- cannabis  material). In either instance, the compound introduced may include nicotine, cannabinoids, and/or flavorants. The flavorants may be from natural sources, such as plant extracts (e.g., tobacco extract,  cannabis  extract), and/or artificial sources. In yet another instance, when the fibrous material includes tobacco and/or  cannabis , the compound may be or may additionally include one or more flavorants (e.g., menthol, mint, vanilla). Thus, the compound within the aerosol-forming substrate may include naturally occurring constituents and/or non-naturally occurring additives. In this regard, it should be understood that existing levels of the naturally occurring constituents of the aerosol-forming substrate may be increased through supplementation. For example, the existing levels of nicotine in a quantity of tobacco may be increased through supplementation with an extract containing nicotine. Similarly, the existing levels of one or more cannabinoids in a quantity of  cannabis  may be increased through supplementation with an extract containing such cannabinoids. 
     The first downstream rim  116  of the first cover  110  and the second downstream rim  126  of the second cover  120  jointly define the passageway  166  (e.g.,  FIG. 3 ) when the first cover  110  and the second cover  120  are coupled with the base portion  130 . The first downstream rim  116  of the first cover  110  and the second downstream rim  126  of the second cover  120  are dimensioned to be small or narrow enough to retain the first aerosol-forming substrate  160   a  and the second aerosol-forming substrate  160   b  within the chamber but yet large or wide enough to permit a passage of an aerosol therethrough when the first aerosol-forming substrate  160   a  and the second aerosol-forming substrate  160   b  are heated by the heater  140 . 
     As noted supra, the base portion  130  includes an engagement assembly  136  configured to facilitate a connection with the first cover  110  and the second cover  120  via the first notch  112  and the second notch  122 , respectively. The engagement assembly  136  may be an integrally formed part of the base portion  130 . In an example embodiment, the engagement assembly  136  of the base portion  130  includes a pair of mating members. The pair of mating members of the engagement assembly  136  may be adjacent to opposite edges of the base portion  130 . Each of the pair of mating members of the engagement assembly  136  may have a head section and a body section, wherein the head section is wider than the body section. For instance, each of the pair of mating members of the engagement assembly  136  may have a T shape corresponding to the T-shaped notch collectively formed by the first notch  112  of the first cover  110  and the second notch  122  of the second cover  120 . 
     As illustrated in  FIGS. 5-6 , the base portion  130  defines a first indentation  132  and a second indentation  134 . As a result, when assembled, the surface of the base portion  130  defining the first indentation  132  and a corresponding surface of the first cover  110  jointly define the first air inlet  152  (e.g.,  FIG. 3 ). Similarly, the surface of the base portion  130  defining the second indentation  134  and a corresponding surface of the second cover  120  jointly define the second air inlet  154  (e.g.,  FIG. 4 ). The first air inlet  152  and the second air inlet  154  are in fluidic communication with the chamber (e.g., chamber  164  in  FIG. 7 ) where the first aerosol-forming substrate  160   a  and the second aerosol-forming substrate  160   b  are disposed along with the intermediate section  144  of the heater  140 . 
     A sheet material may be cut or otherwise processed (e.g., stamping, electrochemical etching, die cutting, laser cutting) to produce the heater  140 . The sheet material may be formed of one or more conductors configured to undergo Joule heating (which is also known as ohmic/resistive heating). Suitable conductors for the sheet material include an iron-based alloy (e.g., stainless steel, iron aluminides), a nickel-based alloy (e.g., nichrome), and/or a ceramic (e.g., ceramic coated with metal). For instance, the stainless steel may be a type known in the art as SS316L, although example embodiments are not limited thereto. The sheet material may have a thickness of about 0.1-0.3 mm (e.g., 0.15-0.25 mm). 
     The heater  140  has a first end section  142 , an intermediate section  144 , and a second end section  146 . The first end section  142  and the second end section  146  are configured to receive an electric current from a power source during an activation of the heater  140 . When the heater  140  is activated (e.g., so as to undergo Joule heating), the temperature of the first aerosol-forming substrate  160   a  and the second aerosol-forming substrate  160   b  may increase, and an aerosol may be generated and drawn or otherwise released through the aerosol outlets  174  of the capsule  100 . The first end section  142  and the second end section  146  may each define an aperture to facilitate an electrical connection with the power source, although example embodiments are not limited thereto. Additionally, because the heater  140  may be produced from a sheet material, the first end section  142 , the second end section  146 , and the intermediate section  144  may be coplanar. Furthermore, the intermediate section  144  of the heater  140  may have a planar and winding form resembling a compressed oscillation or zigzag with a plurality of parallel segments (e.g., eight to twelve parallel segments). However, it should be understood that other forms for the intermediate section  144  of the heater  140  are also possible (e.g., spiral form, flower-like form). 
     In an example embodiment, the heater  140  extends through the base portion  130 . In such an instance, the first end section  142  and the second end section  146  may be regarded as external segments of the heater  140  disposed on an opposite side of the base portion  130  from the engagement assembly  136 . In particular, the intermediate section  144  of the heater  140  may be on the downstream side of the base portion  130 , while the terminus of each of the first end section  142  and the second end section  146  may be on the upstream side of the base portion  130 . During manufacturing, the heater  140  may be embedded within the base portion  130  via injection molding (e.g., insert molding, over molding). For instance, the heater  140  may be embedded such that the intermediate section  144  is between the pair of mating members of the engagement assembly  136 . 
     Although the first end section  142  and the second end section  146  of the heater  140  are shown in the drawings as projections extending from the upstream side of the base portion  130 , it should be understood that, in some example embodiments, the first end section  142  and the second end section  146  of the heater  140  may be configured so as to constitute parts of the upstream end face of the capsule  100 . For instance, the exposed portions of the first end section  142  and the second end section  146  of the heater  140  may be dimensioned and oriented so as to be situated/folded against (e.g., substantially coplanar with) the underside or bottom of the base portion  130 . As a result, the first end section  142  and the second end section  146  may constitute a first electrical contact pad and a second electrical contact pad, respectively, as well as parts of the upstream end face of the capsule  100 . 
       FIG. 7  is a cross-sectional view of the capsule of  FIG. 1 . Referring to  FIG. 7 , when the capsule  100  is assembled, the upstream portions of the first cover  110  and the second cover  120  are coupled with the base portion  130 , while the downstream portions of the first cover  110  and the second cover  120  are received by the end cap  170 . In addition to defining the aerosol outlets  174  (e.g.,  FIG. 1 ), the end cap  170  also defines a cavity  172 . The cavity  172  is downstream from and in fluidic communication with the chamber  164  via the passageway  166 . Specifically, the first air inlet  152 , the second air inlet  154 , the chamber  164 , the passageway  166 , the cavity  172 , and the aerosol outlets  174  (e.g.,  FIG. 1 ) are all in fluidic communication with each other so as to permit a flow of air/aerosol therethrough. 
     As a result, when an electric current is supplied to the heater  140  and air is drawn into the capsule  100 , the air may enter the capsule  100  through the first air inlet  152  and the second air inlet  154  (e.g., through the front face and the rear face of the capsule  100 ). After being drawn into the capsule  100 , the air may flow longitudinally along the intermediate section  144  of the heater  140  and through the aerosol-forming substrate within the chamber  164  (e.g., the first aerosol-forming substrate  160   a  and the second aerosol-forming substrate  160   b  in  FIGS. 5-6 ). Inside the chamber  164 , volatiles are released by the aerosol-forming substrate heated by the intermediate section  144  of the heater  140  to produce an aerosol which is entrained by the air flowing through the chamber  164 , the passageway  166 , and the cavity  172  before exiting the capsule  100  through the aerosol outlets  174 . 
     In an example embodiment, at least one of a filter or a flavor medium may be optionally disposed in the cavity  172  of the end cap  170 . In such an instance, a filter and/or a flavor medium may be disposed in the cavity  172  within the end cap  170  so as to be downstream from the first cover  110  and the second cover  120  such that the aerosol generated within the chamber  164  passes through at least one of the filter or the flavor medium in the cavity  172  before exiting through the at least one aerosol outlet  174 . The filter may reduce or prevent particles from the aerosol-forming substrate from being inadvertently drawn from the capsule  100 , while the flavor medium may release a flavorant when the aerosol passes therethrough so as to impart the aerosol with a desired flavor. The flavorant may be the same as described above in connection with the aerosol-forming substrate. Furthermore, the filter and/or the flavor medium may have a consolidated form or a loose form as described supra in connection with the aerosol-forming substrate. 
       FIG. 8  is a first perspective view of another capsule for an aerosol-generating device according to an example embodiment.  FIG. 9  is a second perspective view of the capsule of  FIG. 8 . Referring to  FIGS. 8-9 , a capsule  200  includes a housing configured to hold an aerosol-forming substrate and to accommodate a heater configured to heat the aerosol-forming substrate to generate an aerosol. The housing of the capsule  200  includes a base portion  230 , a first cover  210 , and a second cover  220 . The base portion  230  includes an engagement assembly (e.g., engagement assembly  236  in  FIG. 10 ) configured to facilitate a connection with the first cover  210  and the second cover  220 . Once connected to the base portion  230 , the first cover  210  and the second cover  220  jointly define an aerosol outlet  274  therebetween. As a result, the capsule  200  may be regarded as one that is of a 3-piece construction. 
     Additionally, when connected, the base portion  230  and the first cover  210  define a first air inlet  252  therebetween. Similarly, the base portion  230  and the second cover  220 , when connected, define a second air inlet  254  therebetween. The first air inlet  252  and the second air inlet  254  are in fluidic communication with the aerosol outlet  274 . As a result, air drawn into the first air inlet  252  and the second air inlet  254  will flow through the capsule  200  to the aerosol outlet  274 . In an example embodiment, the downstream sector of the capsule  200  may taper to a mouth end (e.g., cylindrical end) defining the aerosol outlet  274 . A heater is configured to extend through the base portion  230  such that the first end section  242  and the second end section  246  are visible while the intermediate section of the heater is hidden from view when the capsule  200  is assembled. The heater will be discussed in further detail in connection with subsequent drawings. 
     Although the drawings illustrate the aerosol outlet  274  as a single outlet, it should be understood that example embodiments are not limited thereto. For instance, the aerosol outlet  274  may be defined as a plurality of outlets (e.g., 2-4 outlets). The aerosol outlet  274  may be defined by the first cover  210  and the second cover  220  or, alternatively, by a separate insert or end cap. Additionally, the aerosol outlet  274 , when provided as a plurality of outlets, may be arranged in a linear/sequential manner, in a radial manner, or in an array of rows and columns. Furthermore, the shape of the aerosol outlet  274  (or each of the outlets when a plurality are provided) may be circular, elongated (e.g., elliptical), polygonal (e.g., rounded rectangular), or of another suitable shape. 
       FIG. 10  is a partially exploded view of the capsule of  FIG. 8 .  FIG. 11  is a partially exploded view of the capsule of  FIG. 9 . Referring to  FIGS. 10-11 , the first cover  210  and the second cover  220  are configured to engage with each other and with the base portion  230  during the assembly of the capsule  200 . In an example embodiment, to facilitate an engagement of the first cover  210  with the second cover  220 , the first cover  210  includes a first protrusion  213  and defines a first orifice  215 , while the second cover  220  includes a second protrusion  223  and defines a second orifice  225 . As a result, during assembly, the first protrusion  213  of the first cover  210  will mate with the second orifice  225  of the second cover  220 , while the second protrusion  223  of the second cover  220  will mate with the first orifice  215  of the first cover  210 . The resulting engagement between the first cover  210  and the second cover  220  may be via an interference fit. 
     As illustrated, the first cover  210  also defines one or more of a first notch  212 , a first recess  214 , a first groove  216 , and a first channel  218 . Similarly, the second cover  220  defines one or more of a second notch  222 , a second recess  224 , a second groove  226 , and a second channel  228 . In some instances, the first cover  210  and the second cover  220  may be identical parts. In such instances, orienting the first cover  210  and the second cover  220  to face each other for mating (as well as for coupling with the base portion  230 ) will result in a complementary arrangement. As a result, one part may be used interchangeably as the first cover  210  or the second cover  220 , thus simplifying the method of manufacturing. 
     When the capsule  200  is assembled, the first recess  214  of the first cover  210  and the second recess  224  of the second cover  220  collectively form a chamber  264  (e.g.,  FIG. 12 ) configured to accommodate both an aerosol-forming substrate and an intermediate section  244  of the heater  240 . Additionally, the first interior surface of the first cover  210  further defines a first channel  218  downstream from the first recess  214 , and the second interior surface of the second cover  220  further defines a second channel  228  downstream from the second recess  224 . The first channel  218  and the second channel  228  are configured to collectively form an aerosol channel  268  (e.g.,  FIG. 12 ). Moreover, the first interior surface of the first cover  210  further defines first grooves  216  connecting the first recess  214  to the first channel  218 , and the second interior surface of the second cover  220  further defines second grooves  226  connecting the second recess  224  to the second channel  228 . The first grooves  216  and the second grooves  226  are aligned and dimensioned so as to collectively form passageways  266  (e.g.,  FIG. 12 ) configured to retain the aerosol-forming substrate within the chamber  264  while allowing the aerosol generated to pass through to the aerosol channel  268 . The number of passageways  266  may range from four to eight (e.g., six), although example embodiments are not limited thereto. 
     The first notch  212  in the first cover  210  may be defined as a pair of notches at the upstream corners of the first cover  210 , wherein each notch may be adjacent to/exposed by the upstream end surface of the first cover  210  while bounded/obscured by a corresponding side surface of the first cover  210  (e.g.,  FIG. 11 ). Likewise, the second notch  222  may be defined as a pair of notches at the upstream corners of the second cover  220 , wherein each notch may be adjacent to/exposed by the upstream end surface of the second cover  220  while bounded/obscured by a corresponding side surface of the second cover  220  (e.g.,  FIG. 10 ). Alternatively, the first notch  212  and the second notch  222  may be provided as discussed in connection with the first notch  112  (e.g.,  FIG. 6 ) and the second notch  122  (e.g.,  FIG. 5 ), respectively, so as to also be exposed by a corresponding side surface of the first cover  210  and the second cover  220 , respectively. During assembly, the first notch  212  and the second notch  222  collectively form a T-shaped notch configured to mate with the engagement assembly  236  when the first cover  210  and the second cover  220  are coupled with the base portion  230 . 
     The engagement assembly  236  may be an integrally formed part of the base portion  230 . In an example embodiment, the engagement assembly  236  of the base portion  230  includes a pair of mating members. The pair of mating members of the engagement assembly  236  may be adjacent to and slightly spaced away from the corresponding opposite edges of the base portion  230 . As a result, the engagement assembly  236  may be hidden/obscured from view by the first cover  210  and the second cover  220  when the capsule  200  is assembled. Alternatively, the pair of mating members of the engagement assembly  236  may be positioned against (e.g., flush with) the corresponding opposite edges of the base portion  230 , such as that disclosed in connection with the engagement assembly  136  of capsule  100  (e.g.,  FIG. 5 ). In such an instance, the engagement assembly  236  will still be partially visible when the capsule  200  is assembled. Each of the pair of mating members of the engagement assembly  236  may have a head section and a body section, wherein the head section is wider than the body section. For instance, each of the pair of mating members of the engagement assembly  236  may have a T shape corresponding to the T-shaped notch collectively formed by the first notch  212  of the first cover  210  and the second notch  222  of the second cover  220 . 
     As illustrated in  FIGS. 10-11 , the base portion  230  defines a first indentation  232  and a second indentation  234 . As a result, when the capsule  200  is assembled, the surface of the base portion  230  defining the first indentation  232  and a corresponding surface of the first cover  210  jointly define the first air inlet  252  (e.g.,  FIG. 8 ). Similarly, the surface of the base portion  230  defining the second indentation  234  and a corresponding surface of the second cover  220  jointly define the second air inlet  254  (e.g.,  FIG. 9 ). The first air inlet  252  and the second air inlet  254  are in fluidic communication with the chamber (e.g., chamber  264  in  FIG. 12 ) where the aerosol-forming substrate is disposed along with the intermediate section  244  of the heater  240 . The aerosol-forming substrate (not illustrated) for the capsule  200  may be as described in connection with any of the forms/formats for the first aerosol-forming substrate  160   a  and/or the second aerosol-forming substrate  160   b  of the capsule  100  (e.g.,  FIG. 5 ). As a result, the relevant disclosures above with regard to aerosol-forming substrates should be understood to apply to this section and may not have been repeated in the interest of brevity. 
     A sheet material may be cut or otherwise processed (e.g., stamping, electrochemical etching, die cutting, laser cutting) to produce the heater  240 . The sheet material may be formed of one or more conductors configured to undergo Joule heating (which is also known as ohmic/resistive heating). Suitable conductors for the sheet material include an iron-based alloy (e.g., stainless steel, iron aluminides), a nickel-based alloy (e.g., nichrome), and/or a ceramic (e.g., ceramic coated with metal). For instance, the stainless steel may be a type known in the art as SS316L, although example embodiments are not limited thereto. The sheet material may have a thickness of about 0.1-0.3 mm (e.g., 0.15-0.25 mm). 
     The heater  240  has a first end section  242 , an intermediate section  244 , and a second end section  246 . The first end section  242  and the second end section  246  are configured to receive an electric current from a power source during an activation of the heater  240 . When the heater  240  is activated (e.g., so as to undergo Joule heating), the temperature of the aerosol-forming substrate may increase, and an aerosol may be generated and drawn or otherwise released through the aerosol outlet  274  of the capsule  200 . The first end section  242  and the second end section  246  may each define an aperture to facilitate an electrical connection with the power source, although example embodiments are not limited thereto. Additionally, because the heater  240  may be produced from a sheet material, the first end section  242 , the second end section  246 , and the intermediate section  244  may be coplanar. Furthermore, the intermediate section  244  of the heater  240  may have a planar and winding form resembling a compressed oscillation or zigzag with a plurality of parallel segments (e.g., eight to twelve parallel segments). However, it should be understood that other forms for the intermediate section  244  of the heater  240  are also possible (e.g., spiral form, flower-like form). 
     In an example embodiment, the heater  240  extends through the base portion  230 . In such an instance, the first end section  242  and the second end section  246  may be regarded as external segments of the heater  240  disposed on an opposite side of the base portion  230  from the engagement assembly  236 . In particular, the intermediate section  244  of the heater  240  may be on the downstream side of the base portion  230 , while the terminus of each of the first end section  242  and the second end section  246  may be on the upstream side of the base portion  230 . During manufacturing, the heater  240  may be seated within a slot extending through the base portion  230 . To enhance the seating (e.g., via an interference fit), the heater  240  may be provided with a base insert which covers segments of the heater  240  between the intermediate section  244  and the terminus of each of the first end section  242  and the second end section  246 . As a result, when the heater  240  is introduced through the slot in the base portion  230 , the base insert will be between the heater  240  and the base portion  230  so as to create a relatively close-fit arrangement, thus allowing the base portion  230  to grip the heater  240  in a relatively secure manner. Alternatively, the heater  240  may be embedded within the base portion  230  via injection molding (e.g., insert molding, over molding). For instance, the heater  240  may be embedded such that the intermediate section  244  is between the pair of mating members of the engagement assembly  236 . 
     Although the first end section  242  and the second end section  246  of the heater  240  are shown in the drawings as projections extending from the upstream side of the base portion  230 , it should be understood that, in some example embodiments, the first end section  242  and the second end section  246  of the heater  240  may be configured so as to constitute parts of the upstream end face of the capsule  200 . For instance, the exposed portions of the first end section  242  and the second end section  246  of the heater  240  may be dimensioned and oriented so as to be situated/folded against (e.g., substantially coplanar with) the underside or bottom of the base portion  230 . As a result, the first end section  242  and the second end section  246  may constitute a first electrical contact pad and a second electrical contact pad, respectively, as well as parts of the upstream end face of the capsule  200 . 
     In an example embodiment, the first cover  210  and the second cover  220  are configured to engage with each other and with the base portion  230  such that their adjacent surfaces are substantially flush. For instance, when engaged, the main external surface of the first cover  210  may be flush with the front surface of the base portion  230  (e.g.,  FIG. 8 ). Similarly, in another instance, the main external surface of the second cover  220  may be flush with the rear surface of the base portion  230  (e.g.,  FIG. 9 ). Additionally, in yet another instance, the opposing side surfaces of the base portion  230  may be flush with the adjoining side surfaces of the first cover  210  and the second cover  220 . Furthermore, in yet another instance, the downstream end surface of the first cover  210  may be flush with the downstream end surface of the second cover  220 . 
     When the first cover  210 , the second cover  220 , and the base portion  230  are coupled together, the resulting structure (e.g., housing) of the capsule  200  may have an upstream sector with a form resembling a cuboid with a front face, an opposing rear face, a first side face, an opposing second side face, and an upstream end face. With a cuboid form, the upstream sector of the capsule  200  may have a rectangular cross-section. Alternatively, in other instances, the cuboid form of the upstream sector of the capsule  200  may have a square cross-section. However, it should be understood that example embodiments are not limited thereto. For instance, in lieu of a cuboid form, the upstream sector of the capsule  200  may have a form resembling a cylinder (e.g., elliptic cylinder, circular cylinder). For an elliptic cylinder, the upstream sector of the capsule  200  may have an elliptical cross-section. On the other hand, for a circular cylinder, the upstream sector of the capsule  200  may have a circular cross-section. 
     With regard to the cuboid upstream sector resulting from the coupling of the first cover  210 , the second cover  220 , and the base portion  230  as shown in the drawings, the main external surface of the first cover  210  and the front surface of the base portion  230  may be jointly regarded as the front face (e.g., which defines the first air inlet  252 ). Similarly, the main external surface of the second cover  220  and the rear surface of the base portion  230  may be jointly regarded as the opposing rear face (e.g., which defines the second air inlet  254 ). Additionally, the opposing side surfaces of the base portion  230  and the corresponding side surfaces of the first cover  210  and the second cover  220  may be jointly regarded as the first side face and the opposing second side face of the housing. Moreover, the underside or bottom of the base portion  230  may be regarded as the upstream end face (e.g., from which the first end section  242  and the second end section  246  of the heater extend). As to the housing as a whole, the downstream end surface of the first cover  210  and the corresponding downstream end surface of the second cover  220  may be jointly regarded as the downstream end face. 
     As illustrated, the downstream sector of the capsule  200  may taper to a cylindrical end defining the aerosol outlet  274 . However, it should be understood that example embodiments are not limited thereto. For instance, in lieu of a cylindrical end with a circular or elliptical cross-section, the downstream sector of the capsule  200  may taper to a polygonal end, which may be a cuboidal end with a rectangular or square cross-section. In another instance, the downstream sector of the capsule  200  may taper to a flattened end resembling a wedge, chisel, duckbill shape. 
       FIG. 12  is a cross-sectional view of the capsule of  FIG. 8 . Referring to  FIG. 12 , when the capsule  200  is assembled, the upstream portions/ends of the first cover  210  and the second cover  220  are coupled/engaged with the base portion  230 , while the downstream portions/ends of the first cover  210  and the second cover  220  form a mouth end defining an aerosol channel  268  and an aerosol outlet  274  (e.g.,  FIG. 8 ). The aerosol channel  268  is downstream from and in fluidic communication with the chamber  264  via the passageways  266 . Specifically, the first air inlet  252 , the second air inlet  254 , the chamber  264 , the passageways  266 , and the aerosol channel  268  are all in fluidic communication with each other so as to permit a flow of air/aerosol therethrough. 
     As a result, when an electric current is supplied to the heater  240  and air is drawn into the capsule  200 , the air may enter the capsule  200  through the first air inlet  252  and the second air inlet  254  (e.g., through the front face and the rear face of the capsule  200 ). After being drawn into the capsule  200 , the air may flow longitudinally along the intermediate section  244  of the heater  240  and through the aerosol-forming substrate (not illustrated) within the chamber  264 . Inside the chamber  264 , volatiles are released by the aerosol-forming substrate heated by the intermediate section  244  of the heater  240  to produce an aerosol which is entrained by the air flowing through the chamber  264 , the passageways  266 , and the aerosol channel  268  before exiting the capsule  200  through the aerosol outlet  274 . 
       FIG. 13  is a first perspective view of another capsule for an aerosol-generating device according to an example embodiment.  FIG. 14  is a second perspective view of the capsule of  FIG. 13 . The capsule  300  in  FIGS. 13-14  may resemble the capsule  200  in  FIGS. 8-9  while differing with regard to the internal slots defined by the first cover  310  and the second cover  320  as well as the corresponding external protuberances, which will be discussed in more detail herein. As a result, the relevant disclosures above of the features in common should be understood to apply to this section and may not have been repeated in the interest of brevity. 
     The capsule  300  includes a housing configured to hold an aerosol-forming substrate as described herein and to accommodate a heater configured to heat the aerosol-forming substrate to generate an aerosol. The housing of the capsule  300  includes a base portion  330 , a first cover  310 , and a second cover  320 . The base portion  330  includes an engagement assembly (e.g., engagement assembly  336  in  FIG. 15 ) configured to facilitate a connection with the first cover  310  and the second cover  320 . Once connected to the base portion  330 , the first cover  310  and the second cover  320  jointly define an aerosol outlet  374  therebetween. As a result, the capsule  300  may be regarded as one that is of a 3-piece construction. 
     Additionally, when connected, the base portion  330  and the first cover  310  define a first air inlet  352  therebetween. Similarly, the base portion  330  and the second cover  320 , when connected, define a second air inlet  354  therebetween. The first air inlet  352  and the second air inlet  354  are in fluidic communication with the aerosol outlet  374 . As a result, air drawn into the first air inlet  352  and the second air inlet  354  will flow through the capsule  300  to the aerosol outlet  374 . In an example embodiment, the downstream sector of the capsule  300  may taper to a mouth end (e.g., cylindrical end) defining the aerosol outlet  374 . A heater is configured to extend through the base portion  330  such that the first end section  342  and the second end section  346  are visible while the intermediate section  344  of the heater  340  (e.g.,  FIG. 15 ) is hidden from view when the capsule  300  is assembled. The aerosol outlet  374 , the first air inlet  352 , the second air inlet  354 , the base portion  330 , the first end section  342 , and the second end section  346  in  FIGS. 13-14  may be the same as described in connection with the aerosol outlet  274 , the first air inlet  252 , the second air inlet  254 , the base portion  230 , the first end section  242 , and the second end section  246  in  FIGS. 8-9 . As a result, the relevant disclosures above of the features in common should be understood to apply to this section and may not have been repeated in the interest of brevity. 
       FIG. 15  is a partially exploded view of the capsule of  FIG. 13 .  FIG. 16  is a partially exploded view of the capsule of  FIG. 14 . Referring to  FIGS. 15-16 , the first interior surface of the first cover  310  defines a first slot  317  oriented orthogonally to the first channel  318 , while the second interior surface of the second cover  320  defines a second slot  327  oriented orthogonally to the second channel  328 . Each of the first slot  317  and the second slot  327  may be a half-disk-shaped concavity, although example embodiments are not limited thereto. Additionally, the first cover  310  may have a first external protuberance corresponding to the first slot  317 . Similarly, the second cover  320  may have a second external protuberance corresponding to the second slot  327 . Alternatively, it should be understood that the thicknesses of the first cover  310  and the second cover  320  may be increased such that the depths of the first slot  317  and the second slot  327  do not result in corresponding external protuberances in the first cover  310  and the second cover  320 . 
     When the first cover  310  and the second cover  320  are engaged, the first slot  317  and the second slot  327  collectively form a compartment (e.g., compartment  367  in  FIG. 17 ). The compartment is configured to accommodate at least one of a filter or a flavor medium as described herein. The compartment may be a disk-shaped concavity. However, it should be understood that other shaped compartments (and, thus, other shaped slots) may be provided. For instance, the compartment may be a polygon-shaped (e.g., square-shaped, hexagon-shaped, octagon-shaped) concavity configured to accommodate a similarly shaped filter and/or flavor medium. 
     Unless otherwise described and/or illustrated with regard to differentiating features, it should be understood that the other aspects of the first cover  310  and the second cover  320  in  FIGS. 15-16  may be the same as described in connection with the first cover  210  and the second cover  220  in  FIGS. 10-11 . In particular, the first notch  312 , the first protrusion  313 , the first recess  314 , the first orifice  315 , the first groove  316 , and the first channel  318  in  FIG. 16  may be the same as described in connection with the first notch  212 , the first protrusion  213 , the first recess  214 , the first orifice  215 , the first groove  216 , and the first channel  218  in  FIG. 11 . Similarly, the second notch  322 , the second protrusion  323 , the second recess  324 , the second orifice  325 , the second groove  326 , and the second channel  328  in  FIG. 15  may be the same as described in connection with the second notch  222 , the second protrusion  223 , the second recess  224 , the second orifice  225 , the second groove  226 , and the second channel  228  in  FIG. 10 . 
     In some instances, the first cover  310  and the second cover  320  may be identical parts. In such instances, orienting the first cover  310  and the second cover  320  to face each other for mating (as well as for coupling with the base portion  330 ) will result in a complementary arrangement. As a result, one part may be used interchangeably as the first cover  310  or the second cover  320 , thus simplifying the method of manufacturing. 
     Additionally, the base portion  330  and the heater  340  in  FIGS. 15-16  may be the same as described in connection with the base portion  230  and the heater  240  in  FIGS. 10-11 . In particular, the first indentation  332 , the second indentation  334 , and the engagement assembly  336  of the base portion  330  in  FIGS. 15-16  may be the same as described in connection with the first indentation  232 , the second indentation  234 , and the engagement assembly  236  of the base portion  230  in  FIGS. 10-11 . Likewise, the first end section  342 , the intermediate section  344 , and the second end section  346  of the heater  340  in  FIGS. 15-16  may be the same as described in connection with the first end section  242 , the intermediate section  244 , and the second end section  246  of the heater  240  in  FIGS. 10-11 . As a result, the relevant disclosures above of the features in common should be understood to apply to this section and may not have been repeated in the interest of brevity. 
       FIG. 17  is a cross-sectional view of the capsule of  FIG. 13 . Referring to  FIG. 17 , when the capsule  300  is assembled, the upstream portions/ends of the first cover  310  and the second cover  320  are coupled/engaged with the base portion  330 , while the downstream portions/ends of the first cover  310  and the second cover  320  form a mouth end defining an aerosol channel  368  and an aerosol outlet  374  (e.g.,  FIG. 13 ). The aerosol channel  368  is downstream from and in fluidic communication with the compartment  367 . The compartment  367 , in turn, is in fluidic communication with the chamber  364  via the passageways  366 . Specifically, the first air inlet  352 , the second air inlet  354 , the chamber  364 , the passageways  366 , the compartment  367 , and the aerosol channel  368  are all in fluidic communication with each other so as to permit a flow of air/aerosol therethrough. 
     As a result, when an electric current is supplied to the heater  340  and air is drawn into the capsule  300 , the air may enter the capsule  300  through the first air inlet  352  and the second air inlet  354  (e.g., through the front face and the rear face of the capsule  300 ). After being drawn into the capsule  300 , the air may flow longitudinally along the intermediate section  344  of the heater  340  and through the aerosol-forming substrate (not illustrated) within the chamber  364 . The aerosol-forming substrate for the capsule  300  may be as described in connection with any of the forms/formats for the first aerosol-forming substrate  160   a  and/or the second aerosol-forming substrate  160   b  of the capsule  100  (e.g.,  FIG. 5 ). As a result, the relevant disclosures above with regard to aerosol-forming substrates should be understood to apply to this section and may not have been repeated in the interest of brevity. 
     Inside the chamber  364 , volatiles are released by the aerosol-forming substrate heated by the intermediate section  344  of the heater  340  to produce an aerosol which is entrained by the air flowing through the chamber  364 , the passageways  366 , the compartment  367 , and the aerosol channel  368  before exiting the capsule  300  through the aerosol outlet  374 . Optionally, at least one of a filter or a flavor medium as described herein may be provided within the compartment  367  such that the aerosol generated in the chamber  364  passes through at least one of the filter or the flavor medium before flowing through the aerosol channel  368 . 
       FIG. 18  is a front view of an aerosol-generating device according to an example embodiment. Referring to  FIG. 18 , an aerosol-generating device  1000  (e.g., heat-not-burn aerosol-generating device) may include a capsule  400  and a device body  1025 . In a non-limiting manner, the capsule  400  may be the same as described in connection with the capsule  100 , the capsule  200 , and/or the capsule  300  so as to cover various combinations of the disclosed features. For instance, the capsule  400  may include a housing containing an aerosol-forming substrate and a heater that undergoes resistive heating when activated. The housing may include a base portion, a first cover, and a second cover. The first cover and the second cover may jointly define therebetween a chamber, an aerosol channel, and an aerosol outlet, wherein the aerosol-forming substrate is disposed in the chamber. The heater is supported by the base portion and extends into the chamber. 
     The device body  1025  may define a socket or concavity configured to receive the capsule  400  such that the device body  1025  is mechanically and electrically engaged with the capsule  400 . For instance, the socket or concavity of the device body  1025  may be configured to grip at least two opposite external surfaces (e.g., opposing sidewalls) of the capsule  400 . Alternatively, the device body  1025  and/or the capsule  400  may include a magnet configured to establish a magnetic arrangement such the device body  1025  will attract and retain the capsule  400 . In addition, the device body  1025  may include a first electrode  1055   a  and a second electrode  1055   b  within the socket or concavity that are configured to electrically contact a first end section and a second end section, respectively, of a heater of the capsule  400 . 
     A power source  1035  and control circuitry  1045  may be disposed within the device body  1025  of the aerosol-generating device  1000 . The power source  1035  may include one or more batteries (e.g., lithium ion rechargeable battery). When the capsule  400  is engaged with the device body  1025 , the control circuitry  1045  may instruct the power source  1035  to supply an electric current to the capsule  400  via the first electrode  1055   a  and the second electrode  1055   b  of the device body  1025 . 
     The supply of current from the power source  1035  may be in response to a manual operation (e.g., button-activation) or an automatic operation (e.g., puff-activation when an incoming airflow via the air inlet  1065  is detected). As a result of the current, the aerosol-forming substrate within the capsule  400  may be heated to generate an aerosol. In addition, the change in resistance of the heater may be used by the control circuitry  1045  to monitor and control the aerosolization temperature. The aerosol generated may be drawn from the aerosol-generating device  1000  via the aerosol outlet at the mouth end of the capsule  400 . 
     Thus, during an operation of the aerosol-generating device  1000 , ambient air may be pulled into the device body  1025  via the air inlet  1065 , and a method of generating an aerosol may include supplying an electric current to the capsule  400  so as to heat (e.g., via resistive heating) an aerosol-forming substrate therein. The method may additionally include drawing the aerosol generated within the chamber of the capsule  400  such that the aerosol flows through the aerosol channel and exits the aerosol outlet of the capsule  400 . 
     Further to the non-limiting embodiments set forth herein, additional details of the substrates, capsules, devices, and methods discussed herein may also be found in U.S. application Ser. No. 16/909,131, filed Jun. 23, 2020, titled “CAPSULES INCLUDING INTERNAL HEATERS, HEAT-NOT-BURN (HNB) AEROSOL-GENERATING DEVICES, AND METHODS OF GENERATING AN AEROSOL,” Atty. Dkt. No. 24000NV-000603-US; “U.S. application Ser. No. 16/451,662, filed Jun. 25, 2019, titled “CAPSULES, HEAT-NOT-BURN (HNB) AEROSOL-GENERATING DEVICES, AND METHODS OF GENERATING AN AEROSOL,” Atty. Dkt. No. 24000NV-000522-US; and U.S. application Ser. No. 16/252,951, filed Jan. 21, 2019, titled “CAPSULES, HEAT-NOT-BURN (HNB) AEROSOL-GENERATING DEVICES, AND METHODS OF GENERATING AN AEROSOL,” Atty. Dkt. No. 24000NV-000521-US, the disclosures of each of which are incorporated herein in their entirety by reference. 
     While a number of example embodiments have been disclosed herein, it should be understood that other variations may be possible. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.