Distal airway and alveolar model

Abstract

A breathing simulator is disclosed comprising a rigid porous foam comprising an interconnected open cell network having: (i) macrocells; and (ii) micropores and / or nanopores.

Description

Technical Field

[0001] The present invention discloses a distal airway and alveolar model that can be used to simulate the terminal, transitional and respiratory bronchioles, alveolar ducts and alveolar spaces of the respiratory tract. Specifically, the present invention can be used to simulate the interaction between inhalable agents and the regions of the respiratory tract. Background Art

[0002] Inhalable agents (such as smoke, fumes, aerosolized dust, gas, pollen, bacteria or aerosols produced by medical inhalers) may have neutral, adverse or beneficial effects on the respiratory tract. The nature and amplitude of the observable effects depend on the delivered dose of the inhalant, which is the amount of the test agent or its individual components deposited on or diffused into the respiratory epithelium. The delivered dose is affected by the characteristics of the inhaled test agent and the characteristics of the respiratory tract. The relevant characteristics of the test agent include the physical and chemical characteristics of each component in its concentration, its composition and its components, such as particle size, particle density, vapor pressure, diffusivity or water solubility. The relevant characteristics of the respiratory tract include the geometry and surface characteristics of the respiratory zone gradually changing from the nasal cavity and upper thoracic airway to the distal lung. Therefore, the dose delivered to a given area of ​​the respiratory tract from a given inhalant changes along the respiratory tract. In addition, since the fraction of the inhalant deposited in the upper airway is no longer available for deposition in the distal airway, the composition of the inhalant changes. Therefore, different regions of the respiratory tract are exposed to different test agents, which further increases the heterogeneity of the delivered dose across the respiratory tract.

[0003] The ability to mimic these deposition patterns outside of living organisms will be of great value in the field of in vitro inhalation science. This will allow for physiologically relevant in vitro exposures of cell cultures of respiratory epithelia, such as human respiratory epithelia. Realistic exposure conditions and physiologically relevant dose delivery will increase the in vitro and in vivo translatability of biological responses to such exposures compared to currently applied methods. For example, during the development of inhalable drugs, this will reduce the need for expensive, time-consuming and ethically controversial animal testing and at the same time reduce the risk of failure of candidate drugs during clinical studies.

[0004] There is currently no technology that reliably simulates the interaction between inhaled agents and the entire airway. Idealized or realistic models of the upper airways down to the bronchial bifurcation have been described for several generations and have been constructed and used to study particle deposition during respiration. However, these models are generally not designed to maintain cell cultures for in vitro exposure, do not capture dynamics in the distal airways or alveoli, and do not generate physiologically relevant conditions in terms of respiratory dynamics, surface properties and absorptivity of the airway walls, and humidification of inhaled agents.

[0005] The diameter of the distal airways and alveoli is in the submillimeter range, so gases and small particles present in the inspired air diffuse rapidly and efficiently across the epithelium. In addition, the total cross-sectional area of ​​the airways increases toward more distal regions and eventually reaches approximately 1 m 2 . This design results in a decrease in the flow rate of inspired air towards more distal regions of the respiratory tract from one to ten meters per second in the upper airways to less than 1 cm per second closer to the respiratory zone. The supply of gas (and particles) to the alveoli themselves is driven entirely by diffusion, and convective mass transport does not reach the alveoli. This has profound consequences for the mass transport from inspired air to the respiratory epithelium and blood flow. Specifically, the flow rate in the respiratory zone is optimized to meet the physiological requirement of balancing convective transport of inspired air to and from the alveolar space with diffuse transport of oxygen from the alveolar lumen to and across the alveolar walls in order to optimize blood oxygenation. The distal airways and alveoli are difficult to model due to their structural complexity.

[0006] The apparatus used for in vitro exposure of cell cultures representing the distal airways and alveoli has been described in Tenenbaum-Katan et al. (2018) Biomicrofluidics ( Biomicrofluidics ) 12(4), Stucki et al., (2018) Scientific Reports ( Scientific reports ) 8, 1-3 and Müller et al., (2001) Journal of Insciences ( Insciences J. )》 1, 30-64, but the devices are generally unable to reproduce the physical conditions and / or deposition patterns. On the one hand, this is because the geometry of the device and / or the primary mechanism controlling the deposition of the test material in these devices is not properly aligned with the anatomical structure. On the other hand, these devices may not be connected to a model of the upper airway and therefore cannot shape the physicochemical properties of the test agent in the way used by the respiratory tract, that is, they deliver the test agent independently of the distal airways. In addition, the distal airways and respiratory zone of the respiratory tract are characterized by a large total surface area (e.g., 60-140 m 2In the range of ), the large total surface area can be completely covered by an aqueous solution or liquid lining. The respiratory epithelium separates the volume of air inhaled from the blood circulation supplied from the right ventricle through the pulmonary artery. The thickness of this blood-gas barrier in the respiratory zone is in the micrometer range and below. The full cardiac output of blood in the range of, for example, 4-8 liters / minute reaches the respiratory epithelium through the pulmonary artery. For any compound present in the inhaled air and able to diffuse across the respiratory epithelium, the rapidly exchanging blood acts as an absorbent (sink) that maintains the concentration gradient between the gas and the epithelium at a relatively constant high level. In summary, the large surface area, short diffusion distance, optimized flow rate and relatively high and more or less constant concentration gradient lead to a very efficient gas exchange between the inhaled air and the blood. This is also true for the two gases intended to be exchanged by the lungs - oxygen and carbon dioxide, but obviously also for any other gas present in the inhaled air. The same is true for particles and compounds with low vapor pressure, although they are not dependent on the blood flow for continuous removal from the lung tissue but are delivered at a constant rate; once immersed in the liquid layer lining the epithelium, they will re-enter the gas phase only to a very limited extent, i.e., equilibrium conditions are not reached at all, or only after a very high mass has been transferred to the epithelium.

[0007] WO2019016094 describes a simulated airway, i.e., a device that simulates the macroscopic anatomical features of the airway and can simulate human breathing. WO2020 / 148238 describes a perforated structure that can be inserted into / at a simulated airway, and further refines the anatomical simulation of the airway by adding models of lobar and segmental bronchi and bronchioles. Both WO2019016094 and WO2020 / 148238 can be designed to hold cell cultures, sensors, or microfluidic or mesofluidic devices, and can be used to perform in vitro exposure of biological test systems to test aerosols or gases, and determine the deposition of the test aerosols or gases in vitro under physiologically relevant conditions.

[0008] There is a need in the art for a system that can simulate in vitro the mass transport of aerosols and gases within the distal airways and alveoli of the respiratory zone of the respiratory tract. The present invention seeks to address this need and others. Summary of the invention

[0009] The present disclosure provides a model of the distal airway and alveoli. The model can be used to simulate the terminal, transitional and respiratory bronchioles, alveolar ducts and alveolar spaces of the respiratory tract. The distal airway and alveolar model can be used to simulate the interaction between the inhalable agent and the region of the respiratory tract. To achieve this, the distal airway and alveolar model utilizes a rigid porous foam. The rigid porous foam used in the present disclosure is commercially available and is known to be used in applications including separation technology and filtration (e.g., dust removal, diesel particle filtration, liquid filtration), sound insulation and heat insulation, chemical and thermal process engineering (e.g., catalyst carriers, porous burners), medical technology (e.g., bone substitute materials), and as a carrier for catalysts. It should be understood that rigid porous foams - particularly rigid porous foams containing (i) macropores and (ii) interconnected open-cell networks of micropores and / or nanopores - have not been described for use in the distal airway and alveolar model of the respiratory tract. One reason for this is that its use for this purpose violates the intuition of the technician. This is because the flexible structure will be understood to be more closely similar to the respiratory tract. However, the present inventors have found that rigid porous foams are superior to such flexible structures (such as those made from silicone, rubber, gelatin or similar materials) because such materials do not have the required stability for bimodal or hierarchical pore sizes. This can cause the foam to collapse. Furthermore, reproducible handling and cleaning of flexible structures is difficult to achieve in the laboratory, and strategies for mounting cell cultures within such structures have not been identified to date.

[0010] The rigid porous foam claimed is an open-cell hierarchical network having: (i) macropores; and (ii) micropores and / or nanopores, which represent a model of the distal airways and alveoli in the respiratory tract. One size of the pores (macropores that can simulate the size of the alveoli) can conduct a gas or aerosol supplied to the model, and the other pore sizes (micropores and / or nanopores that can simulate the size of the distal airways) can conduct an aqueous solution, keep this aqueous solution within the network of micropores and / or nanopores, and provide a liquid film on the surface of the macropores. Providing a water film or liquid film on the surface of the macropores allows humidification of the gas that occurs in the alveoli and captures the properties of evaporative mass flow to the gas phase. The liquid film also has the ability to absorb gas, which means that the gas can be dissolved in the liquid lining. Advantageously, this improved model can be configured to match the anatomical and physiological characteristics of the respiratory tract to the greatest extent possible, including: a large and wet surface, an average distance between any location in the test atmosphere and the system wall in the sub-millimeter range, a suitable flow rate, and optimally, active transport of deposited water-soluble materials away from the deposition site. This simulates conditions within the distal region of the respiratory tract, where the diameter of the airways and the diameter of the alveolar sacs are in the sub-millimeter range and the surface is covered by a continuous layer of water or liquid. In one aspect, a breathing simulator is disclosed that includes a rigid porous foam that includes an interconnected open-pore network having: (i) macropores; and (ii) micropores and / or nanopores.

[0011] Suitably, the rigid porous foam is: (i) a ceramic or metal rigid porous foam; or (ii) a ceramic and metal rigid porous foam; preferably, wherein the rigid porous foam is made of: alumina or silicon carbide or oxygen-bonded silicon carbide or sintered silicon carbide or a combination of two or more thereof.

[0012] Suitably, (i) the macropores contain a gas or an aerosol; or (ii) the micropores and / or the nanopores contain an aqueous solution or a liquid; or (iii) the macropores contain a gas or an aerosol and the micropores and / or the nanopores contain an aqueous solution or a liquid.

[0013] Suitably, the micropores and / or the nanopores containing the aqueous solution or the liquid form an aqueous layer or a liquid layer covering a part or the whole of the surface of the macropores.

[0014] Suitably, the rigid porous foam comprises one or more cavities or sockets or recesses or a combination of two or more thereof, preferably wherein the one or more cavities or sockets or recesses or a combination of two or more thereof contain one or more sensing devices or probes or sampling devices or cell cultures.

[0015] Suitably, at least two rigid porous foams are used in the breathing simulator, the at least two rigid porous foams each having a different pore size distribution or each having a different porosity or each having a different material only breathing simulation.

[0016] Suitably, the breathing simulator comprises a pump, and wherein the rigid porous foam is contained or mounted within the pump, preferably wherein the pump is a piston pump.

[0017] In another aspect, disclosed is a use of a rigid porous foam of a breathing simulator for simulating distal airways and alveoli, the rigid porous foam comprising an interconnected open-pore network having: (i) macropores; and (ii) micropores and / or nanopores.

[0018] Suitably, the rigid porous foam is: (i) a ceramic or metal rigid porous foam; or (ii) a ceramic and metal rigid porous foam; preferably, wherein the rigid porous foam is made of: alumina or silicon carbide or oxygen-bonded silicon carbide or sintered silicon carbide or a combination of two or more thereof.

[0019] On the other hand, a method for determining the effect of a test atmosphere on simulated distal airways and alveoli of a respiratory tract is disclosed, the method comprising: (i) providing a breathing simulator according to the present disclosure; (ii) contacting the breathing simulator with the test atmosphere; and determining the effect of the test atmosphere on the simulated distal airways and alveoli of the respiratory tract.

[0020] In another aspect, a rigid porous foam is disclosed for use in a model of distal airways and alveoli of the respiratory tract, the rigid porous foam comprising an interconnected open-pore network having: (i) macropores containing a gas or aerosol; and (ii) micropores and / or nanopores containing an aqueous solution or a liquid, wherein the micropores and / or nanopores containing the aqueous solution or the liquid form a water layer or a liquid layer covering part or all of the surface of the macropores.

[0021] Suitably, the rigid porous foam is: (i) a ceramic or metal rigid porous foam; or (ii) a ceramic and metal rigid porous foam; preferably, wherein the rigid porous foam is made of: alumina or silicon carbide or oxygen-bonded silicon carbide or sintered silicon carbide or a combination of two or more thereof.

[0022] Suitably, (i) the macropores contain a gas or an aerosol; or (ii) the micropores and / or the nanopores contain an aqueous solution or a liquid; or (iii) the macropores contain a gas or an aerosol and the micropores and / or the nanopores contain an aqueous solution or a liquid.

[0023] Suitably, the rigid porous foam comprises one or more cavities or sockets or recesses or a combination of two or more thereof, preferably, wherein the one or more cavities or sockets or recesses or a combination of two or more thereof contain one or more modules for containing or storing cell culture medium and / or at least one microsensor for monitoring conditions in the chamber or for gas sampling or for gas characterization.

[0024] Suitably, the rigid porous foam is contained or mounted within a pump, preferably wherein the pump is a piston pump.

[0025] Some advantages

[0026] Advantageously, the present invention provides an improved model of the distal airways and alveoli as discussed herein.

[0027] Advantageously, models of the distal airways and alveoli can improve the accuracy, reliability, and in vitro-to-in vivo translatability of in vitro methods applied in the context of inhalation toxicology, inhalation posology, and development and preclinical testing of drugs for inhalation therapy.

[0028] Advantageously, models of the distal airways and alveoli allow for determination of deposition of inhalable test agents, how interaction with the distal airways and alveolar models affects the physicochemical properties of inhalable test agents, and for evaluation of how in vitro biological test systems respond to inhalable test agents exposed within such models. To achieve this, models of the distal airways and alveoli can be used in systems that can be configured to allow for introduction of one or more modules, e.g., sensing devices, probes, cell cultures and / or sampling devices, etc., including all necessary electrical, optical, and microfluidic and / or mesofluidic connections.

[0029] Advantageously, the model of the distal airways and alveoli can be configured to match the anatomical and physiological characteristics of the respiratory tract to the greatest extent possible: large and wetted surfaces, average distance between any location within the test atmosphere and the system wall in the sub-millimeter range, appropriate flow rates, and optimally, active transport of deposited water-soluble materials away from the deposition site. This reproduces the conditions within the distal region of the respiratory tract, where the diameters of the airways and alveolar sacs are in the sub-millimeter range and the surfaces are covered by a continuous layer of water or liquid.

[0030] Advantageously, the model of the distal airways and alveoli is not limited to simulating the human airway, but can be extended to any type of airway of interest with appropriate parameterization of the design.

[0031] Advantageously, the model of the distal airways and alveoli is not limited to application in combination with those described in WO2019 / 016094 and WO2020 / 148238. One skilled in the art may design embodiments of the present disclosure that are compatible with any other device for simulating the interaction between an inhalable agent and the respiratory tract. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Embodiments of the present disclosure are described in more detail with reference to the accompanying drawings, in which:

[0033] Figure 1 is a schematic visualization of the pore structure of a rigid porous foam according to an embodiment of the present disclosure. The microstructure and macrostructure of a porous foam that can be used in the model of the distal airways and alveoli described herein are shown. The white areas are macropores that can be filled with gas or aerosol; the gray areas show micropores and / or nanopores that can be filled with aqueous solutions or liquids; the black areas show the ceramic or metal struts of the foam. The radius r of the micropores and / or nanopores is n The radius r of the macropore may be between about 0.1 μm and about 20 μm or between about 0.25 μm and about 25 μm. m It may be between about 200 µm and about 2000 µm or between about 0.1 mm and about 0.4 mm, suitably about 0.25 mm.

[0034] Figure 2 A simulated airway as described in WO2019016094 is shown.

[0035] Figure 3 One embodiment is shown in cross-sectional view.The model of the distal airways and alveoli contained a cylindrical rigid porous foam and a cylindrical or disc-shaped structure providing bifurcated channels and was mounted inside a piston pump.

[0036] Figure 4 Another embodiment is shown in a cross-sectional view. The model of the distal airways and alveoli has three separate rigid porous foams that provide more locations where one or more modules (such as one or more sensing devices, one or more sampling devices, or one or more cell cultures, etc. or a combination of two or more thereof) can be installed inside the piston pump to allow fine tuning of the properties of the overall model of the distal airways and alveoli by, for example, incorporating foams with different pore sizes, different porosities, or different materials.

[0037] Figure 5 Another embodiment is shown in cross-sectional view. A connection between a supply of an aqueous solution or liquid to a rigid porous foam, or a discharge of an aqueous solution or liquid present in the micropores and / or nanopores of the rigid porous foam is shown.

[0038] Figure 6 Another embodiment is shown in cross-sectional view. An alternative connection between a supply of aqueous solution or liquid to the rigid porous foam, or a connection between a discharge of aqueous solution or liquid present in the micropores and / or nanopores of the rigid porous foam is shown.

[0039] Figure 7 is an illustration of a system 10 containing a first pump 40, a second pump 80, and a connection structure 50 as described in WO2019016094. In one embodiment, the rigid foam of the present disclosure is contained inside the second pump 80 (not shown). DETAILED DESCRIPTION

[0040] In certain embodiments, the practice of the present disclosure employs conventional techniques of engineering, microbiology, cell biology, and biochemistry. Biological techniques are fully explained in the following literature, such as Molecular Cloning: A Laboratory Manual, 2nd edition (Sambrook et al., 1989) Cold Spring Harbor Press; Oligonucleotide Synthesis (MJ. Gait, ed., 1984); Methods in Molecular Biology, Humana Press; Cell Biology: A Laboratory Notebook (JE CelMs, ed., 1998) Academic Press; Animal Cell Culture (RI Freshney, ed., 1987); Introduction to Cell and Tissue Culture (JP Mather and PE Roberts, 1998) Plenum Press; Cell and Tissue Culture: Laboratory Procedures (J. E. Mather, ed., 1996) Academic Press; and Laboratory Procedures (A. Doyle, IB. Griffiths and DG Newell, eds., 1993-8) John Wiley and Sons; Methods in Enzymology (Academic Press, Inc.); Current Protocols in Molecular Biology, (FM Ausubel et al., eds., 1987); PCR: The Polymerase Chain Reaction (Mullis et al., eds., 1994). Unless otherwise noted, procedures employing commercially available kits and reagents will generally be used according to protocols defined by the manufacturer.

[0041] The technical terms and expressions used herein are generally given the meanings commonly applied thereto in the relevant art. All term definitions used herein apply to the entire content of this application.

[0042] The term "comprising" does not exclude other elements or steps.

[0043] The indefinite article "a" or "an" does not exclude a plurality.

[0044] The term "and / or" means, for example, (a) or (b) or both (a) and (b).

[0045] As used herein, the terms "comprising, comprises and comprised of" are synonymous with "including, includes" or "containing, contains" and are inclusive or open-ended and do not exclude additional, unrecited members, elements or method steps. The term "consisting of is meant to exclude additional components and to have only the listed elements and no more.

[0046] As used herein, when referring to a measurable value such as a parameter, amount, time duration, etc., the term "about" is intended to cover variations from and to the specified value, specifically, variations of + / - 10% or less, preferably + 1-5% or less, more preferably + / - 1% or less, and still more preferably + / - 0.1% or less from the specified value, as long as such variations are suitable for making in the present disclosure. It should be understood that the value to which the modifier "about" refers is itself also explicitly and preferably disclosed.

[0047] The present disclosure may be used for a variety of applications in studying the respiratory tract. For example, embodiments have utility in studying the deposition and / or condensation of one or more components present in a test atmosphere on the internal surfaces of a device. Embodiments also provide for the evaluation of a test atmosphere, which may be studied during its passage through a device to study changes in aerosol concentration and / or aerosol particle growth and / or aerosol particle shrinkage. The effects of a test atmosphere on a biological test system present within a device may be studied in embodiments of the present disclosure.

[0048] The model of the distal airway and alveoli described herein comprises one or more commercially available rigid porous foams. For example, the foam can be purchased from Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Winterbergstr. 28 01277 Dresden, Germany and Ultramet, 12173 Montague Street, Pacoima, CA 91331, USA. The rigid porous foam can be made of ceramic foam or metal foam. It can be manufactured to have various pore sizes, various pore size distributions and different amounts of open and closed porosity. Ceramic foam can be manufactured by several methods fully described in the art, such as replication methods (Boettge et al., (2013) Journal of Materials Research ( Journal of Materials Research )》 28, 2220-2233), direct foaming of ceramic slurries (Zheng et al., (2021) Journal of the Asian Ceramic Society ( Journal of Asian Ceramic Societies ) 9, 24-29), 3D printing (Minas et al., (2016) Advanced Materials ( Advanced Materials )》 28, 9993-9999) or dealloying (Song et al., (2018) Corrosion Science ( Corrosion Science )》 134, 78-98). In one such method, known as the replication method, a component made of open-cell polyurethane foam is impregnated with a ceramic slurry. Excess material is pressed out so that only the surface of the polymer struts is covered with ceramic material. The wet ceramic film is dried and the foam part is debindered, thereby burning out the polymer foam. In a final step, the ceramic is sintered according to the specific sintering conditions of the material. As a result, the ceramic foam component has an almost similar cellular structure and geometry compared to the starting polymer foam part.

[0049] Materials used to make ceramic foams include carbides and nitrides of boron, aluminum, silicon, titanium and zirconium, cordierite. In one embodiment, the use of ceramic foams is preferred.

[0050] Methods for making metal foams are described in Tatt et al., ASM Science Journal ( ASM Sc. J .)”, (2021), 16 and Mooraj et al., (2020) Materials Express ( Scripta Materialia), 177, 146-150. Materials used to make metal foams include gold, titanium or iron.

[0051] Thus, the rigid porous foam may be a ceramic or metal rigid porous foam, or a ceramic and metal rigid porous foam. In one embodiment, the rigid porous foam is made of: alumina or silicon carbide or oxygen-bonded silicon carbide or sintered silicon carbide or a combination of two or more thereof, suitably, an alumina ceramic foam.

[0052] The properties of foams (such as pore size distribution, homogeneity, mechanical stability, surface properties, porosity, flow resistance or capillary activity) are well described in the art and can be fine-tuned by material selection, production methods, surface treatments and coatings (see e.g., Hammel et al., (2014) International Journal of Ceramics (Ceramics)). Ceramics International )” 40, 15351-15370 and Costacurta et al., (2007) Journal of the American Ceramic Society ( J. Am. Ceram. Soc. )》90,2172–2177).

[0053] In an embodiment of the invention, the rigid porous foam is not made of only carbon.

[0054] The rigid porous foam according to the present disclosure has a hierarchical pore size because the hierarchical pore size includes: (i) macropores; and (ii) micropores and / or nanopores. The foam is structurally rigid to provide the desired stability to the bimodal or hierarchical pore size of the foam. The stiffness must be sufficient to prevent the macropores from collapsing during foam deflation. Since the difference between the capillary activity of the macropores and the micropores and / or nanopores disappears temporarily, the collapse may cause flooding of the macropores. It may also reduce the gas permeability. The amount of stiffness can be measured using Young's modulus. As the skilled person will understand, Young's modulus is a mechanical property that measures the tensile stiffness of a solid material. Various methods are available to measure the Young's modulus of elasticity of a material. For example, the Young's modulus of elasticity can be estimated by acquiring one or more atomic force microscope (AFM) images of the material and applying the Derjaguin-Muller-Toporov (DMT) mechanical contact model to the withdrawal curve. Alternatively, the Young's modulus can be calculated by measuring the slope of the unloading curve of a load-displacement diagram obtained by mechanical compression of the material. For metallic and / or ceramic rigid cellular foams, the minimum value of the Young's modulus of rigid cellular foams (i.e., the value at which significant blocking of the macropores can be expected) is about 20 kPa.

[0055] A rigid porous foam is an open pore network having: (i) macropores; and (ii) micropores and / or nanopores. The macropores are capable of conducting a gas or aerosol (e.g., an inhalable test agent) supplied to the distal airways and alveolar model. The micropores and / or nanopores are capable of being filled with an aqueous solution or liquid, such as water, that can be retained and conducted. The aqueous solution or liquid is retained within the network of micropores and / or nanopores to provide a water film or liquid film on the surface of the macropores. The micropores and / or nanopores are present within the ceramic or metal struts that form the macropores of the rigid porous foam. A schematic visualization of the pore structure of a rigid porous foam is shown in FIG. Figure 1 As shown. The micropores and / or nanopores can be filled with an aqueous solution or liquid, and the macropores can be filled with a gas or an aerosol. Since the ceramic or metal walls of the macropores of the rigid porous foam can be covered with open micropores and / or open nanopores that are open to the macropores, the aqueous solution or liquid present in the micropores and / or nanopores forms a water layer or liquid layer covering all or part of the surface of the macropores. Therefore, both the macropores and the micropores and / or nanopores form an open, interconnected continuous pore network in the foam. In this interconnected network, pairs of macropores are connected by continuous channels formed by macropores; pairs of micropores and / or nanopores are connected by continuous channels formed by micropores and / or nanopores; and micropores and / or nanopores are connected to macropores by continuous channels formed by micropores and / or nanopores and macropores.

[0056] The size of the macropores can simulate the size of the alveoli, and thus the radius of the macropores can correspond to the radius of the alveoli. The radius of the macropores can be between about 0.1 to about 0.4 mm, or between about 0.1 to about 0.3 mm, or between about 0.2 to about 0.4 mm, or between about 0.2 to about 0.3 mm, or about 0.25 mm. The radius of the macropores can be between about 100 μm and about 2000 μm, or between about 200 μm and about 2000 μm.

[0057] The radius of the micropores and / or nanopores is typically between about 0.1 µm and about 50 µm, or between about 0.1 µm and about 40 µm, or between about 0.1 µm and about 30 µm, or between about 0.1 µm and about 20 µm, or between about 0.1 µm and about 10 µm, or between about 0.25 µm and about 25 µm.

[0058] The density of cells in the rigid porous foam can be at least about 30 cells / inch, at least about 45 cells / inch, at least about 60 cells / inch, or at least about 80 cells / inch. In certain embodiments, the density of cells in the rigid porous foam is 40 to 50 cells / inch. In certain embodiments, the density of cells in the rigid porous foam is about 45 cells / inch.

[0059] The total surface area of ​​the rigid porous foam may be at least 70 m 2 , preferably 100 meters 2 or more.

[0060] Without wishing to be bound by theory, it is possible to fill the micropores and / or nanopores but not the macropores with an aqueous solution or liquid due to the capillary action of the foam, which can be described by Equation 1:

[0061]

[0062] Equation 1

[0063] The pressure difference ΔP across the surface of the aqueous liquid present in the capillary container relative to the air above this surface is the surface tension γ (in joules) of the aqueous solution or liquid under consideration. 2 ) and its contact angle θ with the material of the capillary container. r is the radius of the capillary container (in meters). ΔP represents the negative pressure of the aqueous solution or liquid relative to the surrounding air (in the application described herein, atmospheric pressure). The contact angles of solid materials with water vary greatly, and in order to observe capillary rise, the contact angle should be less than 90°. For example, the contact angle of glass is zero, and similar values ​​can be assumed for many ceramic materials. From Equation 1, it can be seen that if, in a stratified foam, the average diameter of the micropores and / or nanopores is an order of magnitude (ten times) smaller than the average diameter of the macropores, it can be estimated (ignoring the effects of surface roughness and irregularities in the foam) that the negative pressure in the aqueous solution or liquid below its surface spanning the micropores and / or nanopores is ten times greater than the negative pressure below the surface of the aqueous solution or liquid spanning the macropores (the pressure and contact angle in the surrounding air are the same for both pore types). Therefore, if the aqueous solution or liquid supplied to the rigid porous foam is maintained at a negative pressure whose absolute value is greater than the negative pressure generated by the capillary action of the macropores but less than the negative pressure generated by the capillary action of the micropores and / or nanopores, the micropores and / or nanopores of the rigid porous foam will be filled with the aqueous solution or liquid but the macropores will not be filled. In one embodiment, the average diameter of the micropores and / or nanopores is about one-tenth of the average diameter of the macropores. In another embodiment, the aqueous solution or liquid supplied to the rigid porous foam is maintained at a negative pressure whose absolute value is greater than the negative pressure generated by the capillary action of the macropores but less than the negative pressure generated by the capillary action of the micropores and / or nanopores.

[0064] Another aspect of the present disclosure relates to a method for filling the micropores and / or nanopores of a rigid porous foam as described herein with an aqueous solution or liquid but not filling the macropores, wherein the rigid porous foam comprises an interconnected open-pore network having: (i) macropores; and (ii) micropores and / or nanopores, the method comprising: (i) supplying the aqueous solution or liquid to the rigid porous foam under a negative pressure whose absolute value is greater than the negative pressure generated by capillary action of the macropores but less than the negative pressure generated by capillary action of the micropores and / or nanopores; and (ii) filling the micropores and / or nanopores of the rigid porous foam with the aqueous solution or liquid but not filling the macropores.

[0065] In the case of a sufficiently large difference between the average size of the micropores and / or nanopores and the average size of the macropores, the drain can be connected to a system (e.g., a pump) containing the foam. If the aqueous solution or liquid present in the drain is set to a negative pressure greater than the negative pressure applied to the supply of the aqueous solution or liquid but less than the negative pressure induced by the capillary action of the micropores and / or nanopores, a flux of the aqueous solution or liquid from the supply to the drain can be induced while keeping the micropores and / or nanopores filled with the aqueous solution or liquid. Such a drain can act as a simulated blood flow and can stabilize the concentration gradient between the gas or aerosol present on the surface of the rigid porous foam and the aqueous solution or liquid lining to a certain extent.

[0066] The capillary action of the 30, 45 and 60 pores / inch metal or ceramic rigid porous foam types is sufficient to maintain a water column greater than 20 cm in height (ΔP greater than 2000 Pascals) without flooding the macropores or increasing the rigid porous foam's resistance to airflow through the microporous network.

[0067] If desired, the distal airway and alveolar model can be a combination of one or more rigid porous foams. In certain embodiments, one or more rigid porous foams can be combined with one or more different foams or structures that accommodate multiple bifurcated channels. One such structure described in WO2020 / 148238 relates to a perforated structure comprising a perforated envelope shell that accommodates one or more branch channels, wherein each perforation is an open end of one or more branch channels. The foam structure providing multiple bifurcated channels is preferably made of a ceramic or metal material that contains micropores and / or nanopores (not macropores) and is capable of holding and / or conducting an aqueous solution or liquid as described herein. The bifurcated channels within the structure preferably summarize the anatomical structure of the lung in terms of channel length, bifurcation pattern, bifurcation angle, and channel diameter. Such structures can be produced by the same method as the layered foams described herein. Due to the low complexity of the 3D geometry of such structures (e.g., there is no layered structure), it is possible to perform 3D printing of ceramic precursors followed by sintering (Minas et al., supra) or 3D printing of metal materials (Mooraj et al., supra).

[0068] Computational and empirical methods can be used to identify the optimal pore size distribution for a specific application. Rigid porous foams can have high (large) porosity and produce the same effects on the flow of gas or aerosol through them as described in WO2019016094A1. Figure 1 The rigid porous foam may provide the same or lower resistance to gas or aerosol flow therethrough than any portion of the conduction of the respiratory tract or the extrathoracic airway.

[0069] The rigid porous foam may be composed of a plurality of individual units that provide a means for establishing a leak-proof connection between them. In embodiments comprising two or more individual units of rigid porous foam (e.g., Figure 4 In the embodiment of ), each individual structure can include the same structure or different structures, such as the same or different pore size distribution. For example, it may be desirable to adjust the pore size distribution based on specific experimental needs (or, for example, simulation of deep lung diseased states). Figure 4 In the embodiment of the present invention, three separate rigid porous foams 401a, 401b and 401c are shown. The presence of two or more separate rigid porous foams allows the introduction of more locations where one or more modules can be inserted, such as one or more sensing devices, sampling devices or cell cultures, etc. The presence of two or more separate rigid porous foams can allow the properties of the overall model of the distal airways and alveoli to be fine-tuned by incorporating rigid porous foams of different pore sizes, porosities or materials, for example.

[0070] The rigid porous foam and / or individual cells of the rigid porous foam may be connected to a source or sources of an aqueous solution or liquid present in the micropores and / or nanopores.

[0071] The rigid porous foam and / or individual cells of the rigid porous foam may be connected to a drain or drains towards which the aqueous solution or liquid supplied from the source or sources may be discarded.

[0072] Rigid porous foam can also be used to contain or hold one or more modules. If multiple modules are used, the modules can be of the same type or different types. Such modules can be used to monitor operations and / or conduct experiments and / or collect samples and / or hold cell cultures, etc. For example, a module can hold or store a cell culture medium containing optional cell cultures, or be used to monitor conditions during an experiment or for gas or liquid sampling or for gas characterization, etc. A module can be a receptacle capable of holding an aqueous solution or liquid, such as a cell culture medium. A module can be a device, such as a probe. Such devices can be used to monitor internal system conditions or for testing atmospheric characterization or for sampling, etc. The operation of a module can be controlled by a computer. A module can be a culture chamber, such as a biological test system such as a cell culture or airway epithelial cells and / or alveolar epithelial cells, can be placed in the culture chamber to test atmospheric exposure. A module that holds a quartz crystal microbalance can be used. As required, a module can be placed in a rigid porous foam or near the surface of a rigid porous foam. One or more cavities, receptacles or recesses may be included in the rigid porous foam in which one or more of the modules may be placed and held or stored.

[0073] The rigid porous foam may contain one or more bifurcated channels. The bifurcated channels may bifurcate. The bifurcated channels may exist within a structure made of a rigid ceramic or metal material containing micropores and / or nanopores. Figure 3 An embodiment containing bifurcated channels can be seen in WO2020 / 148238. In this embodiment, the distal airway and alveolar model contains a cylindrical rigid porous foam 301 and a proximal cylindrical or disc-shaped structure 302 that provides a bifurcated channel. There is also an additional more proximal airway model 307, such as the airway model described in WO2020 / 148238, and is connected to the disc-shaped structure 302. The openings of the more proximal airway model 307 bifurcate to terminate in a limited number of smaller distal openings.

[0074] The rigid porous foam may be mounted within the breathing simulator in such a manner that sufficient space is left at a suitable location at the surface of the rigid porous foam to place and retain one or more of the various modules.

[0075] If the model of the distal airways and alveoli comprises multiple rigid porous foams or a combination of rigid porous foams and one or more structures that provide multiple bifurcated channels, the model of the distal airways and alveoli can be connected in a manner that leaves sufficient space to place and retain one or more of the various modules between the separate parts.

[0076] For ease of use, the rigid porous foam can be formed into any desired shape. This can facilitate the intended use of the rigid porous foam, such as in a breathing simulator. Non-limiting examples of suitable shapes are cylindrical or disc-shaped or rectangular. The rigid porous foam shape can be surrounded by radial walls to contain the shaped foam. The radial walls are typically composed of a different material than the foam. In one embodiment, the different material is non-porous. In another embodiment, the different material is a synthetic material, such as epoxy resin or metal or a combination thereof.

[0077] Elements that can contact the rigid porous foam include a bridging structure that can contact the rigid porous foam. This bridging structure can be used for any intended purpose, such as facilitating contact of an aqueous solution or liquid circuit with the foam. The circuit can be configured to supply or drain an aqueous solution or liquid from the rigid porous foam. The contact can be achieved by gluing or welding the bridging structure to the foam, or it can be part of a 3D printed design of the foam. Figure 5 Embodiments can be seen in which there is a connection between a supply of an aqueous solution or liquid to a rigid porous foam, or a connection between a discharge port for an aqueous solution or liquid present in the micropores and / or nanopores of the rigid porous foam. The bridging structure 503 provides a connection to, for example, a microfluidic or mesofluidic conduit 504, which originates from a reservoir of an aqueous solution or liquid or another aqueous solution or liquid that may be located outside the pump. The connection to the microfluidic and / or mesofluidic system establishes a constant supply of an aqueous solution or liquid driven by capillary action of the micropores and / or nanopores of the rigid porous foam, evaporation of water inside the rigid porous foam, and / or negative pressure applied at the discharge port.

[0078] An example of a bridging structure is a microporous and / or nanoporous bridge between an aqueous or liquid circuit and a foam. The microporous and / or nanoporous bridge can be made of various materials, such as fibers or sponge materials (such as cellulose acetate fibers), and preferably a flexible and easily deformable material, so that the shape of the microporous and / or nanoporous bridge adapts to the shape of the rigid porous foam at the connection site and thereby maximizes the contact area with the foam. Figure 6Such an embodiment can be seen in . A bridging structure 602 (which can be glued or welded to the rigid porous foam 601, for example, or it can be part of a 3D printed design of the foam) allows the connection of a circuit (supply or discharge of aqueous solutions or liquids) through microfluidic and / or mesofluidic conduits 603. A microporous and / or nanoporous bridge 604 is inserted into the bridging structure 602 to establish contact with the rigid porous foam 601.

[0079] An example of a rigid porous foam that can be used according to the present disclosure is an alumina ceramic rigid porous foam having a pore density of 45 pores / inch and an accessible pore volume of 19347 mm 3 , the separation pore volume is 5 mm 3 , and the total pore volume is 19352 mm 3 The accessible porosity is 85.65%, the isolated porosity is 0.024%, and the total porosity is 85.67%. The average pore size is 0.82 ± 0.15 mm. The total volume of the rigid porous foam is 31487 mm 3 . The rigid porous foam was highly homogeneous with negligible isolated porosity. The flow resistance of the rigid porous foam was measured before and after foam wetting. The ΔP across the foam was found to be in the range of 2-10 Pa and physiologically relevant flow rates within the range of pressure differences established between the conducting airways and the alveolar space in the human lung during normal breathing. Flooding of the macropores was limited. Efficient water transfer from less than 3% to greater than 75% rH to the gas phase (10 L / min) was achieved in about 0.6 seconds, indicating excellent air humidification and excellent capillary activity in the foam. The capillary ΔP was greater than 2.5 kPa, indicating efficient water supply for humidification. Particle retention in the rigid porous foam was found to meet the requirements with respect to particle size and number.

[0080] Another aspect of the present disclosure relates to a rigid porous foam used as a model of the distal airways and alveoli of the respiratory tract, the rigid porous foam comprising an interconnected open-pore network having the following: (i) macropores, the macropores containing a gas or aerosol; and (ii) micropores and / or nanopores, the micropores and / or the nanopores containing an aqueous solution or a liquid, and wherein the micropores and / or the nanopores containing the aqueous solution or the liquid form a water layer or a liquid layer covering part or all of the surface of the macropores. The rigid porous foam generally has the characteristics of the rigid porous foam previously described. It will be understood that this rigid porous foam can be integrated or incorporated into a breathing simulator, such as the pump of the breathing simulator previously described. The pump can be a piston pump. As previously described, the use of this rigid porous foam in a breathing simulator for simulating distal airways and alveoli is also disclosed.

[0081] Models of distal airways and alveoli comprising rigid porous foam may be conveniently incorporated into a breathing simulator, such as a component of a breathing simulator, which component may be a pump, etc. Breathing simulators are described in the art, such as in WO2019016094, WO2020 / 148238, WO2022040247 and WO2016118935. Figure 3 , Figure 4 , Figure 5 and Figure 6 An exemplary embodiment in which a model of distal airways and alveoli is incorporated into the interior of a pump of a breathing simulator is shown. For example, if the breathing simulator contains a pump, then the model of the distal airways and alveoli can be incorporated into the interior of the pump, which can be a piston pump. Advantageously, this can be achieved without affecting the functionality of the breathing simulator or its components. A leak-proof connection can be conveniently established between the model of the distal airways and alveoli and the breathing simulator. In one embodiment, one or more rigid porous foams described herein can be coupled to a model of the lungs, such as the model of the lungs described in WO2019 / 016094A1. According to this embodiment, the rigid porous foam can be placed such as Figure 2 The pump shown in Section 5 is compatible with the bronchial tree model and the more proximal airway model ( Figure 2 The more proximal airway model connects the lung model to the trachea model ( Figure 2 The model can be used to fix it in the lung pump ( Figure 2 5) and used to build a bronchial tree model ( Figure 2 The model of the distal airway and alveoli can be connected to a supply of aqueous solution or liquid and / or a drain of aqueous solution or liquid.

[0082] An embodiment of the present disclosure is now described in which a rigid porous foam is mounted inside a piston pump 300. The piston pump 300 may form part of a breathing simulator. Figure 3306, a centrally located opening 306 is provided to which an airway model 307, such as the airway model described in WO2020 / 148238A1, is connected, and the airway model can be used to simulate the effect of a conducting airway tree. The airway model 307 provides a proximal opening 308, to which one or more additional proximal airways, such as a model of a bronchus, can be connected, if desired. The opening of the more proximal airway model 307 is bifurcated to terminate at a limited number of smaller distal openings at or very close to the inner plane of the piston pump base plate 304. Optionally, the base plate 304 of the piston pump provides additional openings 309 through which one or more sensors, probes, electronic connections or microfluidic or mesofluidic connections can be inserted. There may be multiple such openings or a single opening. The opening provides a structure that hermetically seals the internal volume of the pump from the surrounding environment. Such structures have been fully described in the art, and in the simplest case, such structures include perforated silicon plugs, through which the connector passes and seals the perforations in the pump base plate 304. Optionally, the base plate 304 of the piston pump may also provide yet additional openings 310, through which the rigid porous foam 301 and / or structure 302 can be connected to a supply of an aqueous solution or liquid (e.g., water), and / or to a discharge port for an aqueous solution or liquid and / or to electronic devices required for, for example, heating and / or monitoring temperature. The rigid porous foam 301 is centrally located within the piston pump and is mounted, for example, by means of screws 311 which protrude through the walls 312 of the rigid porous foam 301, the disc-shaped structure 302 and the base plate 304. The screws may, for example, be stuck in nuts 313 by which the rigid porous foam 301 and the disc-shaped structure 302 are pressed against the base plate 304. In the depicted embodiment, the radial walls 312 of the rigid porous foam 301 preferably have a different texture and / or a different material than the core of the rigid porous foam. For example, the radial walls 312 may be made of a ceramic or metal material that is the same as the core of the rigid porous foam 301 but does not provide macropores, only micropores and / or nanopores, and therefore does not conduct aerosols or gases and provides high capillary action. Alternatively, the radial walls 312 of the rigid porous foam 301 may be made of a synthetic material, such as epoxy resin or metal. As Figure 3The radial wall 312 depicted in the figure provides mechanical stability for fixing the rigid porous foam by screws 311, but alternative embodiments may omit the radial wall 312 in order to increase the total cross-sectional area of ​​the flow path through the foam. The contact between the rigid porous foam 301 and the disc-shaped structure 302 and between the disc-shaped structure 302 and the pump base plate 304 can be sealed, for example, by gaskets or O-rings 314. In this configuration, the suction stroke of the piston 304 forces the gas and aerosol to pass through the more proximal airway model 307, and the distal airway and alveolar model containing the rigid porous foam 301 and the distal airway model 302 into the pump cylinder, and the compression stroke of the piston forces the gas and aerosol present in the pump through the rigid porous foam 301, the distal airway model 302, and the more proximal airway model 307. Between the pump base plate 304 or the more proximal airway model 306 and the more distal airway model 302, and between the more distal airway model 302 and the rigid porous foam 301, a gasket or O-ring 314 introduces a gap 315. The gap between the more proximal airway model 306 and the more distal airway model 302 is used to connect the channels present in the two models, because the channels are not necessarily located at the same radial and tangential positions in the two models. The gap between the more distal airway model 302 and the rigid porous foam 301 is used to evenly connect the foam to the channels present in the airway model ,Right now The test agent is prevented from entering the rigid porous foam 301 to locally limit the location of the channels present in the more distal airway model 302. In addition, the gap 315 between the pump base plate 304 or the more proximal airway model 306 and the more distal airway model 302, and the gap between the more distal airway model 302 and the rigid porous foam 301 provide locations (not shown) where one or more modules of appropriate size and shape, such as cell culture, sampling devices, probes or sensing devices, etc., can be placed.

[0083] Figure 4 An alternative embodiment of a positioning pump 400 comprising three separate rigid porous foams is shown. The elements of the pump body, namely the radial walls of the rigid porous foams, the gaskets or O-rings and the gaps between the separate elements are similar in function and structure to the more proximal airway model. Figure 3The piston pump embodiment 300 shown has the same function and structure as described. The presence of three separate rigid porous foams 401a, 401b and 401c provides the introduction of more locations, where one or more modules, such as one or more sensing devices, sampling devices or cell cultures, etc., can be inserted, and at the same time allows the characteristics of the overall model of the distal airways and alveoli to be fine-tuned by incorporating foams with, for example, different pore sizes, porosities or materials. The piston pump 400 has a cylinder wall 403, a base plate 404 and a piston 405. The base plate 404 provides a centrally positioned opening 406, through which an airway model 407 as described in WO2020 / 148238 is connected. The airway model 407 provides a proximal opening 408, to which one or more additional proximal airways, such as a model of a bronchus, can be connected if desired. The opening of the more proximal airway model 407 is bifurcated to terminate at a limited number of smaller distal openings at or very close to the inner plane of the piston pump base plate 404. Optionally, the base plate 404 of the piston pump provides additional openings 409 through which one or more sensors, probes, electronic connections or microfluidic or mesofluidic connections can be inserted. There may be multiple such openings or a single opening. The opening provides a structure that hermetically seals the internal volume of the pump from the surrounding environment. Such structures have been fully described in the art, and in the simplest case, such structures include perforated silicon plugs, through which the connector passes and seals the perforations in the pump base plate 404. Optionally, the base plate 404 of the piston pump may also provide additional openings 410, through which the foam 401a, 401b and 401c and / or the structure 402 can be connected to a supply of an aqueous solution or liquid (e.g., water), and / or to a discharge port for an aqueous solution or liquid and / or to electronic devices required for, for example, heating and / or monitoring temperature. The rigid porous foam 401a, 401b and 401c is centrally located in the piston pump and is mounted, for example, by screws 411, which protrude through the walls 412 of the foams 401a, 401b and 401c, the disc-shaped structure 402 and the bottom plate 404. The screws can, for example, be stuck in nuts 413, by which the foams 401a, 401b and 401c and the disc-shaped structure 402 are pressed against the bottom plate 404. In the depicted embodiment, the radial walls 412 of the foams 401a, 401b and 401c preferably have a different texture and / or a different material than the core of the rigid porous foam. For example, the radial walls 412 can be made of a ceramic or metal material that is the same as the core of the foams 401a, 401b and 401c but does not provide macropores, only micropores and / or nanopores, and therefore does not conduct aerosols or gases and provides high capillary action. Alternatively, the radial walls 412 of the foams 401a, 401b, and 401c may be made of a synthetic material, such as epoxy or metal. Figure 4The radial wall 412 depicted in FIG. 4 provides mechanical stability for fixing the rigid porous foam by screws 411, but alternative embodiments may omit the radial wall 412 in order to increase the total cross-sectional area of ​​the flow path through the foam. The contact between the rigid porous foam 401a, 401b, and 401c and the disc-shaped structure 402 and between the disc-shaped structure 402 and the pump base plate 404 can be sealed, for example, by gaskets or O-rings 414. In this configuration, the suction stroke of the piston 404 forces the gas and aerosol to pass through the more proximal airway model 407, and the distal airway and alveolar model composed of the foam 401a, 401b, and 401c and the distal airway model 402 into the pump cylinder, and the compression stroke of the piston forces the gas and aerosol present in the pump through the foam 401a, 401b, and 401c, the distal airway model 402, and the more proximal airway model 407. Between the pump base plate 404 or the more proximal airway model 406 and the more distal airway model 402, and between the more distal airway model 402 and the rigid porous foam 401a, 401b, and 401c, a gasket or O-ring 414 introduces a gap 415. The gap between the more proximal airway model 406 and the more distal airway model 402 is used to connect the channels present in the two models, because the channels are not necessarily located at the same radial and tangential positions in the two models. The gap between the more distal airway model 402 and the rigid porous foam 401a, 401b, and 401c is used to evenly connect the rigid porous foam to the airway model. The channel in The test agent is prevented from entering the foams 401a, 401b, and 401c to locally limit the location of the channels present in the more distal airway model 402. In addition, the gap 415 between the pump base plate 404 or the more proximal airway model 406 and the more distal airway model 402, and the gap between the more distal airway model 402 and the rigid porous foams 401a, 401b, and 401c provide locations (not shown) where one or more modules of appropriate size and shape can be placed, such as one or more cell cultures, sampling devices, probes or sensing devices, etc.

[0084] Figure 5 An embodiment of a connection between a supply of an aqueous solution or liquid to a rigid porous foam, or a discharge port for an aqueous solution or liquid present in the micropores and / or nanopores of the rigid porous foam is shown. The figure shows an enlarged section of a cross-sectional view of a lung model 500 containing a distal airway and alveolar model. In the depicted embodiment, the radial wall 501 of the rigid porous foam 502 is made of a porous material (e.g. ，The rigid porous foam is made of the same material as the rigid porous foam itself, but the porous material does not contain macropores but only micropores and / or nanopores. The micropores and / or nanopores form a continuous porous connection between the rigid porous foam and the pump volume located between the pump cylinder wall and the distal airway and alveolar model. The bridging structure 503 provides a connection with, for example, a microfluidic or mesofluidic conduit 504, which originates from a reservoir of an aqueous solution or liquid located outside the pump. The bridging structure can, for example, be glued or welded to the surface of the radial wall 501 of the rigid porous foam. Alternatively, it can be part of a 3D printed design of the rigid porous foam. The bridging structure 503 preferably provides an inner cavity 505, thereby increasing the contact area between the fluid present in the bridging structure 503 and the radial wall 501 of the rigid porous foam. The connection with the microfluidic or mesofluidic system establishes a constant supply of aqueous solution or liquid driven by the capillary action of the micropores and / or nanopores of the foam, the evaporation of water inside the rigid porous foam, and / or the negative pressure applied at the discharge port. When the aqueous solution or liquid in the microfluidic or mesofluidic conduit is set to an appropriate negative pressure relative to the surrounding air, the capillary action of the micropores and / or nanopores present in the radial walls 501 of the rigid porous foam 502 and the pillars of the rigid porous foam prevents or reduces the entry of air into the micropores and / or nanopores, and establishes a water or liquid continuum from the reservoir through the supplied microfluidic or mesofluidic conduit, the micropores and / or nanopores of the distal airway and alveolar model, and the microfluidic or mesofluidic conduit of the discharge port to the reservoir of the discharge port.

[0085] Figure 6 An alternative possible embodiment of a connection between a supply of an aqueous solution or liquid to a rigid porous foam, or a discharge port for an aqueous solution or liquid present in the micropores / nanopores of the rigid porous foam is shown. This figure shows an enlarged section 600 of a cross-sectional view of a lung model containing an embodiment of a distal airway and alveolar model, wherein the layered rigid porous foam 601 is not surrounded by radial walls, but allows gas or aerosol on its entire surface. Such embodiments cannot be used in Figure 5The method shown is connected to a source and / or discharge port of an aqueous solution or liquid because the direct connection of the aqueous solution or liquid to the macropores of the rigid porous foam eliminates the closed contact between the capillary activity of the micropores and / or nanopores, which causes air to enter the water or liquid circuit. In order to overcome this limitation, it is necessary to establish a microporous and / or nanoporous bridge between the water or liquid circuit and the rigid porous foam. This can be established, for example, by providing a bridging structure 602, which can be, for example, glued or welded to the rigid porous foam 601, or can be part of the foam 3D printing design. The bridging structure 602 allows the water or liquid circuit (supply or discharge port of the aqueous solution or liquid) to be connected through a microfluidic or mesofluidic conduit 603. The microporous and / or nanoporous bridge 604 is inserted into the bridging structure 602 so that it establishes contact with the rigid porous foam 601. The microporous and / or nanoporous bridges may be composed, for example, of a fiber or sponge material (e.g., cellulose acetate), and are preferably flexible and easily deformable, so that the shape of the microporous and / or nanoporous bridges adapts to the shape of the rigid porous foam at the connection site and thereby maximizes the contact area with the microporous and / or nanoporous network in the foam. A combination of a bridge made of a dense cellulose acetate fiber bundle of about 2 cm in length and an alumina ceramic hierarchical rigid porous foam having a macropore density of 45 pores / inch, an average macropore size of 820 μm, and a micropore and / or nanopore size of less than 30 μm was successfully tested. The bridge can maintain a closed water or liquid circuit at a negative pressure of more than 2000 Pascals and allows a continuous supply of water to the alumina foam driven by evaporation.

[0086] In another aspect, a system for determining the interaction between a test atmosphere and a simulated respiratory tract is described, the system comprising: (a) a first pump, the first pump comprising: (i) a chamber, the chamber being configured to hold a first volume of gas including the test atmosphere; (ii) a first port, the first port being suitable for receiving and outputting gas and comprising a valve for regulating gas flow through the first port, the valve being movable between an open position and a closed position, wherein in the open position the valve is open to the test atmosphere or ambient air; (iii) a second port, the second port being suitable for outputting and receiving gas and comprising a valve for regulating gas flow through the second port, the valve being movable between an open position and a closed position; and (iv) a motor for controlling operation of the first pump; (b) a second pump, the second pump comprising: (i) a chamber, the chamber being configured to hold a second volume of gas, wherein the first volume of gas and the second volume of gas are different; and (ii) a port, the port (iii) a piston plate in the chamber, the piston plate comprising one or more orifices for taking in or flowing gas into the chamber, wherein one or more of the orifices or each orifice comprises a valve, the valve being movable between an open position and a closed position and being capable of regulating the taking in or the flowing in of gas; (iv) an airway and alveolar model of the present disclosure, the airway and alveolar model of the present disclosure being housed in the second pump; and (iv) a motor, the motor being used to control the operation of the second pump; (c) a connecting structure, the connecting structure being operable to transfer the gas from the first pump to the second pump; and (d) one or more openings, the one or more openings being located in a wall of the first pump or the second pump or the connecting structure or a combination of two or more thereof, the opening being capable of receiving a module, the module being used to hold or store a matrix comprising a cell culture medium and / or for monitoring conditions in the chamber or for gas sampling or for at least one microsensor for gas characterization.

[0087] The gas may be the test atmosphere, or the gas may comprise the test atmosphere. Figure 7A system 10 according to this aspect of the present disclosure is shown. The system 10 includes at least two pumps 40, 80. Two or more pumps 40, 80 are connected to each other. In some embodiments, the two or more pumps 40, 80 are connected to each other by a branching hollow structure 50. Each pump 40, 80 can be operated by its own separate motor 41, 81, or two or more pumps can be operated by the same motor 41, 81 as needed. The entire system 10 can be located in a climate housing 11 equipped with a thermostat 12 to control the temperature in the housing 11. The chambers of the pumps 40, 80 can be configured to represent the internal volumes of different compartments of the respiratory tract (e.g., the respiratory tract of a human or animal). They can be configured to provide a displacement at least as large as the maximum achievable volume intake in the corresponding compartment of the respiratory tract. Specifically, one (first) pump 40 can represent the volume of the oral cavity and oropharyngeal cavity (e.g., the oral cavity and oropharyngeal cavity of a human or animal). Another second pump 80 can represent the volume of a lung cavity or a portion thereof (such as the lumen of an individual lung lobe or a smaller subunit), in particular a lung cavity or a portion thereof of a human or animal. The airway and alveolar model of the present disclosure can be housed inside the second pump 80. The branched hollow connection structure 50 can represent the size of a conducting airway, in particular a conducting airway of a human or animal, such as one or more of the nasopharyngeal cavity, hypopharynx, larynx, trachea, bronchi, and bronchiolar structures directly reaching the respiratory bronchioles. The branched hollow connection structure 50 can represent the size of a conducting airway, including the nasopharyngeal cavity, hypopharynx, larynx, trachea, bronchi, and bronchiolar structures directly reaching the respiratory bronchioles. The sizes (e.g., diameters and lengths) of the different sub-portions of the connection structure 50 and the branching pattern can be similar to a tree of a conducting airway. The branched hollow structure 50 can be connected to the central openings 43, 83 in the base 44, 84 of the chambers 42, 82 of each pump 40, 80. In certain embodiments, a plurality of openings, holes or spigots 51 may be present on the base 44, 84 of the chamber 42, 82, which may be arranged symmetrically around the central opening 43, 83. A valve 44a directly at the connection between the pump 40 and the connecting structure 50 may be used to allow the pump 40 to be sealed with all other system parts. The pump 40 representing the oral cavity may have one or more openings 43 through which the test atmosphere and dilution air may leave the pump 40 toward the branch hollow structure 50. The inlet and outlet points of the test atmosphere 90 are generally located on the piston plate 45 of the pump 40, appropriately located at its center. It may run through the hollow piston axis 46, and a valve 44a, such as a three-way valve, may be present on the top of the hollow piston axis. In an embodiment, the valve 44a may be closed or opened toward a test atmosphere source or ambient air. An array of one or more (e.g., multiple) orifices 47 through which ambient air may enter the system is optionally arranged on the piston plate 45 in a radial arrangement.One or more valves 48 (e.g., multiple) on one or more or all of the orifices can be used to allow one or more of these orifices 47 to be opened or closed. In some embodiments, each orifice 47 is controlled by a valve 48. In some embodiments, an array of one or more orifices (e.g., multiple) through which ambient air can enter the system can be optionally arranged in a radial arrangement on the piston plate 84 of the second pump. One or more valves (e.g., multiple) can be used to allow one or more of these orifices to be opened or closed. In some embodiments, each orifice is controlled by a valve. In some embodiments, an array of one or more orifices (e.g., multiple) through which ambient air can enter the system can be optionally arranged in a radial arrangement on the piston plates of the first pump and the second pump. Advantageously, the branch hollow structure 50 can be disconnected from the pump 40, 80. Advantageously, the branch hollow structure 50 can be disassembled into its main parts. This can allow easy access to replace or remove the test system and / or for cleaning. The base 44, 84 of the pump 40, 80 can be removed to replace / remove the test system and for cleaning. In the base 44, 84 of each pump 40, 80, and in different parts of the connecting structure 50, an opening, hole or socket 51, such as a threaded or unthreaded opening, a threaded or unthreaded hole or a threaded or unthreaded socket 113, 213 can be located therein. The opening, hole or socket 51 can be located in various positions, such as on the base 44, 84 of one or more of the pumps 40, 80, or can be arranged around the central opening 43, 83 or at various selected positions in the branch hollow structure 50, appropriately on the lower side of the branch hollow structure 50 or any combination thereof. The opening, hole or socket 51 can be used to allow various modules 112, 212 or devices to be installed therein or thereon, which can be used to monitor the operation of the system 10 and / or conduct experiments and / or collect samples, etc. Examples of such modules are described herein. Advantageously, therefore, the pumps 40, 80 used in the system 10 can not only be used to deliver the test atmosphere, but also can be used as an exposure chamber.

[0088] Depending on the requirements of the configured system, the modules used may be suitable for various purposes. For example, the module may be suitable for accommodating or storing cell culture media or for monitoring conditions in chambers 42, 82, or for gas or liquid sampling or for gas characterization, etc. The module may be located on the base 44, 84 of the first pump 40 and / or the second pump 80 and / or in the wall of the connecting structure 50. In a specific embodiment, one or more modules may be configured to accommodate or store a matrix containing a cell culture medium. According to this embodiment, one or more modules may be a receptacle capable of holding a liquid or solution. The cell culture medium may contain or may contact a cell culture, such as a 2-dimensional or 3-dimensional cell culture. In certain embodiments, one or more modules may be capable of holding or positioning at least one microsensor as a substitute or supplement for a cell culture medium matrix. In certain embodiments, a module suitable for accommodating or storing a matrix including a cell culture medium and / or at least one microsensor further comprises a microfluidic channel and a microfluidic pump optionally connected thereto. The module will generally be positioned in a horizontal plane of one or more of the walls of the first pump 40 or the second pump 80 or the connecting structure 50.

[0089] Test atmospheres such as gases and aerosols can be studied, and test atmospheres can be generated by various methods. For many applications, for example, for testing tobacco products or universal medical inhalers, etc., the test atmosphere generation can be driven by a pump that may be present in a breathing simulator to generate the negative pressure required for generating and extracting the test atmosphere, which means that advantageously there is no need to use an aerosol generator / smoking machine. The test atmosphere can be an aerosol, such as smoke, or the aerosol can be derived from smoke. As used herein, the term 'smoke' is used to describe a type of aerosol generated by smoking articles such as cigarettes or by burning aerosol-forming materials. Smoke includes a variety of reagents, which can be provided as separate compounds for study when required. Examples of such agents include nicotine-free dry particulate matter, carbon monoxide, formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, methyl-ethyl ether ketone, butyraldehyde, benzo[a]pyrene, phenol, m-cresol, o-cresol, p-cresol, catechol, resorcinol, hydroquinone, 1,3-butadiene, isoprene, acrylonitrile, benzene, toluene, pyridine, quinoline, styrene, N'-nitrosonornicotine (NNN), N'-nitrosoanatabine (NAT), N'-nitrosoanabasine (NAB), 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone (NNK), 1-aminonaphthalene, 2-aminonaphthalene, 3-aminobiphenyl, 4-aminobiphenyl, nitric oxide (NO), nitrous oxide (NOx), cyanhydric acid, ammonia, arsenic, cadmium, chromium, lead, nickel, selenium, and mercury.

[0090] When the aerosol is smoke, a smoking machine may be used to generate the aerosol. The smoking machine may be attached to the breathing simulator. Thus, the smoking machine contains and lights a cigarette and provides the aerosol directly to the breathing simulator. A defined number of puffs per cigarette and a defined number of puffs per minute of exposure may be used, and the number of cigarettes may be varied to accommodate the exposure time. A reference cigarette (such as reference cigarette 3R4F) may be used as a source of smoke and smoked on a smoking machine that substantially complies with the International Organization for Standardized Smoking Protocols (ISO 2000).

[0091] The use of a control atmosphere, such as an atmosphere that does not contain the test atmosphere, is also contemplated. The use of a control atmosphere can help determine the impact of the test atmosphere compared to the control atmosphere.

[0092] The breathing simulator may be connected to the smoking machine by a suitable conduit which provides a flow path for the smoke to the breathing simulator. The smoke may be delivered by the conduit with or without a carrier gas (e.g. air). Where a carrier gas is used, the conduit preferably comprises an inlet for introducing the carrier gas into the conduit to mix with the smoke flow. The conduit may comprise at least one inlet for introducing or injecting a standard reference (e.g. nicotine) into the breathing simulator for calibration purposes. The smoke flow will typically be controlled by the breathing simulator.

[0093] The smoking machine may be a linear or rotary smoking machine. Suitably, the smoking machine is operated to smoke a plurality of smoking articles simultaneously so that cumulative smoke from the plurality of smoking articles can be collected and analysed. Suitable smoking machines for use with the present disclosure are well known to the skilled person.

[0094] The present disclosure may be used to analyse mainstream smoke produced by a smoking article during a smoking test."Mainstream smoke" refers to the smoke drawn through a smoking article and inhaled by a consumer during use.

[0095] The test atmosphere may come from an "aerosol generating device", which is a device that interacts with an aerosol-forming substrate to generate an aerosol. An example of an aerosol is smoke. The aerosol-forming substrate may be part of an aerosol-generating article. The aerosol generating device may comprise one or more components suitable for generating an aerosol from an aerosol-generating substrate. The aerosol generating device may be an electrically heated aerosol generating device, which is an aerosol generating device comprising a heater that is operated by electricity to heat the aerosol-forming substrate of an aerosol-generating article to generate an aerosol. The aerosol generating device may be a gas-heated aerosol generating device, i.e., a device heated by a carbon-containing heat source, other exothermic chemical reactions, or a heat sink. Other suitable methods of generating aerosols are well known in the art. The aerosol generating device may be a device that interacts with the aerosol-forming substrate of an aerosol-generating article to generate an aerosol that can be directly inhaled into the lungs of a user through the user's mouth.

[0096] Another example of an 'aerosol generating device' is an inhalation device (inhaler), which is typically used to deliver an aerosol containing an active ingredient, such as a medically active compound. Such inhalation devices are typically used to deliver an aerosolized

[0097] Drugs. They can be used to treat respiratory and other diseases. Such inhalers are well known in the art and are typically of the pressurized metered type, dry powder type or atomizer type. Typically, the medicament is in the form of a pressurized formulation containing fine particles of one or more drug compounds suspended in a liquefied propellant, or a solution of one or more compounds dissolved in a propellant / cosolvent system. Such formulations are well known in the art.

[0098] As used herein, the term 'aerosol-forming substrate' relates to a substrate capable of releasing volatile compounds that can form an aerosol. Such volatile compounds can be released by heating the aerosol-forming substrate. The aerosol-forming substrate can be adsorbed, coated, impregnated or otherwise loaded onto a carrier or support. The aerosol-forming substrate can suitably be part of an aerosol-generating article or a smoking article. In certain applications, the aerosol-forming substrate is included in an aerosol-generating article, such as a rod-shaped aerosol-generating article, such as a heated aerosol-generating article or a heated cigarette. The aerosol-generating article has a suitable size and shape for engagement with an aerosol-generating device so that the aerosol-forming substrate is in contact with the heater.

[0099] The aerosol-forming substrate may comprise a medically active compound or medicament, such as an antibiotic or anti-inflammatory agent that can be delivered to a patient through the respiratory tract.Numerous medical inhalation devices (inhalers) are known and are routinely prescribed for the treatment of a variety of respiratory and non-respiratory related diseases.

[0100] Aerosol forming substrate can comprise nicotine.Aerosol forming substrate can comprise tobacco.Aerosol forming substrate can comprise tobacco-containing material containing volatile tobacco aroma compounds, for example, which is released from aerosol forming substrate when heated.In certain embodiments, aerosol forming substrate can comprise homogenized tobacco material, for example, fallen leaf tobacco.As used herein, "homogenized tobacco material" refers to the material formed by agglomerating particle tobacco.Homogenized tobacco can be in the form of sheet material.Homogenized tobacco material can have an aerosol forming agent greater than 5% by dry weight content.Alternately, homogenized tobacco material can have an aerosol forming agent between 5 % by weight and 30 % by weight by dry weight content.The sheet material of homogenized tobacco material can be formed by agglomerating particle tobacco, which is obtained by grinding or otherwise pulverizing one or both of tobacco leaf blade and tobacco leaf stem.Alternately or in addition, the sheet material of homogenized tobacco material can be included in one or more of tobacco dust, broken cigarette and other particle tobacco byproducts formed during the processing, operation and transportation of tobacco. The sheet of homogenized tobacco material may contain one or more inherent binders that are endogenous binders of tobacco, one or more external binders that are exogenous binders of tobacco, or a combination thereof to help agglomerate the particulate tobacco; alternatively or in addition, the sheet of homogenized tobacco material may contain other additives, including but not limited to tobacco and non-tobacco fibers, aerosol formers, humectants, plasticizers, flavorings, fillers, aqueous solvents and non-aqueous solvents, and combinations thereof.

[0101] Cell cultures for the present disclosure include 2-dimensional cell cultures and 3-dimensional cell cultures. As described herein, cell cultures may be included in one or more foams in the foam. Cell cultures may be exposed to a test atmosphere so that the effect of the test atmosphere on the cell culture may be determined. Two or more cell cultures may be located at different locations in a rigid porous foam so that the impact of the test atmosphere on the cell cultures at these different locations of the simulated respiratory tract may be determined. 2-dimensional cell cultures involve growing cells in a flat layer on a plastic surface, which allows the study of several aspects of cell physiology and responses to stimuli (such as test atmospheres), but they do not reflect the true structure and architecture of an organ. In a 2-dimensional monolayer, the extracellular matrix, intercellular and cell-matrix interactions are lost, which are essential for differentiation, proliferation and cell function. 3-dimensional culture systems may form functional tissues with features similar to those observed in vivo. Compared to 2-dimensional culture systems, 3-dimensional cell cultures allow cells to interact with their surroundings in all three dimensions and are more physiologically relevant. Such cells can show improvements in terms of viability, proliferation, differentiation, morphology, response to stimulation, drug metabolism, gene expression and protein synthesis. 3D cell cultures can produce specific tissue-like structures in a more physiologically relevant way than traditional 2D cell monolayers, and simulate the functions and responses of real tissues. Several 3D tissues that simulate human organs are commercially available. Lung 3D organotypic tissues can be prepared using primary human cells grown at an air-liquid interface (ALI), where these cells will differentiate and form functional tissues. These 3D tissues have close morphological similarities and metabolic characteristics to human bronchial tissues. They are composed of basal cells, goblet cells and ciliated cells arranged in a pseudostratified structure. Similar to the lungs, there are actively beating cilia, allowing the study of their function and activity. Compared with human lungs, similar levels of mRNA encoding xenobiotic enzymes have been found in these 3D ALI cultures. In addition, these tissues can be maintained for a long time in vitro.

[0102] According to the present disclosure, this distal airway and alveolar model is an appropriate model for exploring the effects of test atmospheres, etc. The term '3-dimensional cell culture' includes any method of providing cell culture in 3 dimensions with or without the use of a matrix or scaffold. A variety of different 3-dimensional cell culture methods have been developed, including spheroid culture and organotypic culture.

[0103] Cells used in the present disclosure can be separated from tissues or fluids using methods well known in the art. The cells can be differentiated from stem cells, such as embryonic stem cells or induced pluripotent stem cells, or directly differentiated from somatic cells. Cells and cell lines can be or can be derived from human or animal subjects or human or animal cells, including any of a variety of mammalian species, appropriately, humans, but including rats, mice, pigs, rabbits and non-human primates, etc. Cells and cell lines can be obtained from commercial sources. In certain embodiments, human cells need to be used. Lung cells including lung epithelial cells are the cell types of interest. Bronchial and / or airway epithelial cells can be used in the present disclosure. Human bronchial epithelial cells can be collected by brushing donor lungs during bronchoscopy procedures. In one embodiment, lung cells are normal human bronchial epithelial (Normal Human Bronchial Epithelial, NHBE) cells. Lung epithelial cells can be cultured into a monolayer of undifferentiated cells, or further developed into organotypic lung epithelial cell-like tissues at the air-liquid interface. Cells can be established at the air-liquid interface using the following method. Briefly, epithelial cells can be cultured in flasks to increase the cell number. After the incubation period, the cells are detached from the flasks, counted and plated onto inserts. On these inserts, the cells are incubated with culture medium on the apical and basal sides. This stage ensures that the cells will divide and completely cover the insert, thus forming epithelial cells. Next, the apical culture medium is removed, the basal culture medium is retained, and replaced with a more complete culture medium. The culture is incubated like this for another period of time. In the meantime, the cells will differentiate into three cell types: basal cells, goblet cells and ciliated cells. At the end of maturation, the culture is ready for use. The use of an air-liquid interface to culture human nasal epithelial cells is described in the Journal of Visualized Experiments ( J Vis Exp .) (2013), 80, 50646. Lung epithelial cells can be obtained from human or animal subjects with various pathologies, including subjects classified as smokers or non-smokers.

[0104] Airway and alveolar cell cultures were published in the European Respiratory Journal ( European Respiratory Journal)》, (2019)54: 1900742. Adult tracheal, bronchial, and small airway epithelial cells can be isolated from donor lungs obtained from transplant procedures, from surgically resected tissue, or from bronchial brushings obtained during bronchoscopy. Nasal epithelial cells can be obtained from nasal brushings. Airway epithelial cells are commercially available from companies such as Lonza and Epitheliix as frozen vials or cultures. Epithelial cells can be dissociated (separating cells from each other and from the extracellular matrix and from unwanted cells) by protease treatment. Selective culture media can be used to inhibit the outgrowth of other cell types (such as fibroblasts). Most procedures utilize cells immersed in culture medium and culture tissue culture plastics coated with extracellular matrix (such as collagen). Culturing epithelial cells in Transwells on microporous membranes at the air-liquid interface promotes the differentiation of airway basal epithelial cells into mucosal epithelial cultures similar to in situ airway epithelium, while enabling relevant exposure protocols to study substances in the air. Alveolar epithelial cells can be collected from adult lung tissue from normal appearing tissue following surgery. Isolation of AEC2s typically includes additional steps (such as differential adhesion and magnetic bead sorting) to separate these AEC2s from other cells (such as macrophages and fibroblasts). Primary alveolar epithelial cells are also available from commercial suppliers. Culturing lung epithelial cells in Transwells allows for culture at an air-liquid interface. Epithelial cells can also be grown on collagen layers embedded with fibroblasts. A variety of methods can be used to characterize epithelial cell cultures based on the structure, morphology, and expression of unique cell-specific markers, including electron and confocal microscopy, immunostaining, and gene expression analysis by RT-PCR. Unique functional features include ciliary beat frequency of airway cells and surfactant synthesis by AEC2. Alveolar epithelial cells are derived from induced pluripotent stem cells (iPSCs) and are able to form 3D structures under organotypic culture (see, for example, E Life ( Elife )”, 4(2015), p. e05098; ​​Stem Cell Reports ( Stem Cell Rep )》, 3(2014), pp. 394-403; Cell Stem Cell ( Cell Stem Cell )”, 21(2017), pp. 472-488.e10, and Nature Methods ( Nat. Methods )》, 14(2017), pp.1097-1106). iScience )》, (2022), 25, 2, 10378 describes an alveolar epithelial-derived distal lung cell line.

[0105] 3D lung epithelial cells have been derived from airway basal cells (see Proceedings of the National Academy of Sciences of the United States of America Proc Natl Acad Sci USA)”, (2009) 106, 12771-5) and from alveolar cells (see Journal of Clinical Research ( J Clin Invest )”, (2013) 123, 3025-3036) and from iPSC-derived airway or alveolar cells (see Development ( Development )”, (2017), 144, 986-997 and Current Pathobiology Reports ( Curr Pathobiol Rep )”, (2017) 5, 223-231).

[0106] The present disclosure can be used for a variety of applications to study the effects of test atmospheres on terminal, transitional and respiratory bronchioles, and / or the effects on the alveolar ducts and / or the effects on the alveolar spaces of the respiratory tract, and optionally the effects on other parts of the respiratory tract as needed. For example, the present disclosure can be used to study the in vitro inhalation toxicology of one or more of the bronchioles and / or alveolar ducts and / or alveolar spaces of the respiratory tract. For example, the present disclosure can be used to study aerosol dynamics (e.g., aerosol particle deposition and gas absorption into cell culture) or study the metabolic activity or transport of test atmospheres (e.g., aerosol molecules) across bronchioles and / or alveolar ducts and / or alveolar spaces of the respiratory tract. The present disclosure can be used to test the effects of aerosols, smoke or tobacco products, or the effects of inhalers (such as medical inhalers). The present disclosure can be used to test the effects of aerosols, smoke or tobacco products, or the effects of medical inhalers on cells at one or more parts of the respiratory tract.

[0107] One aspect relates to a method for determining the effect of a test atmosphere on a cell culture (such as one or more cell cultures) contained in a simulated respiratory tract, the method comprising: (a) providing a respiratory simulator as described herein, wherein the system contains a cell culture; and (b) comparing the cell culture before and / or after exposure to the test atmosphere, wherein a difference between the cell culture before and / or after exposure to the test atmosphere indicates that the test atmosphere affects the cell culture.

[0108] In embodiments where differences between cell cultures are determined after the cells are exposed to a test atmosphere, cell cultures exposed to the test atmosphere can be compared to cell cultures that have not been exposed to the test atmosphere or to cell cultures exposed to a control atmosphere (e.g., an atmosphere that does not contain the test atmosphere). According to this embodiment, differences between cell cultures exposed to the test atmosphere and cell cultures that have not been exposed to the test atmosphere, or differences between cell cultures exposed to the test atmosphere and cell cultures exposed to a control atmosphere (e.g., an atmosphere that does not contain the test atmosphere), indicate that the test atmosphere affects the cell cultures.

[0109] The effects of the test atmosphere can be studied in the presence of one or more agents. Agents can include, but are not limited to, drugs, toxins, pathogens, proteins, nucleic acids, antigens, antibodies, and compounds, etc. Examples of effects that can be measured include oxygen consumption, carbon dioxide production, cell viability, protein expression, enzyme activity, permeation, permeability barrier function, surfactant production, response to cytokines, transporter function, cytochrome P450 expression, albumin secretion, toxicity, etc.

[0110] Multiple assays may be run in parallel with varying concentrations of test atmospheres and / or reagents to obtain differential responses to the various concentrations.

[0111] The reagent can be any test compound of interest and includes small organic compounds, polypeptides, peptides, higher molecular weight carbohydrates, polynucleotides, fatty acids and lipids, aerosols or one or more components of aerosols, etc. The test compound can be screened individually, or with a collection of compounds or combinatorial libraries. Test compounds can be obtained from various sources including libraries of synthetic or natural compounds. Libraries of natural compounds in the form of bacteria, fungi, plants and animal extracts can be used. Libraries produced naturally or synthetically and compounds modified by conventional chemical, physical and biochemical means can be used to produce combinatorial libraries. Known agents can be subjected to directed or random chemical modifications, such as acylation, alkylation, esterification, acidification to produce structural analogs for screening.

[0112] The one or more variables that can be measured include elements of cells, subcellular materials, subcellular components, or cell products. For example, the toxicology of the test atmosphere can be measured. Aerosol dynamics (e.g., aerosol particle deposition and gas absorption into cell culture) can be measured. By further example, the metabolic activity and / or transport of molecules can be studied.

[0113] Further aspects of the disclosure are set out in the following numbered paragraphs:

[0114] 1. A breathing simulator comprising a rigid porous foam comprising an interconnected open-pore network having: (i) macropores; and (ii) micropores and / or nanopores.

[0115] 2. A breathing simulator according to paragraph 1, wherein the rigid porous foam is: (i) a ceramic or metal rigid porous foam; or (ii) a ceramic and metal rigid porous foam.

[0116] 3. A breathing simulator according to paragraph 2, wherein the rigid porous foam is made of: aluminum oxide or silicon carbide or oxygen-bonded silicon carbide or sintered silicon carbide or a combination of two or more thereof.

[0117] 4. A breathing simulator according to any one of the preceding paragraphs, wherein the rigid porous foam contains walls and pillars, and wherein the pillars of the rigid porous foam contain micropores and / or nanopores, and wherein the walls of the macropores of the rigid porous foam are covered with the micropores and / or the nanopores that are open toward the macropores.

[0118] 5. A breathing simulator according to any of the preceding paragraphs, wherein the macropores are capable of conducting a gas or aerosol supplied to the rigid porous foam.

[0119] 6. A breathing simulator according to any one of the preceding paragraphs, wherein the micropores and / or the nanopores are capable of: (i) conducting an aqueous solution or a liquid supplied to the rigid porous foam; and (ii) retaining the aqueous solution or the liquid within the micropores and / or the nanopores.

[0120] 7. A breathing simulator according to any of the preceding paragraphs, wherein: (i) the macropores contain gas or aerosol; or (ii) the micropores and / or the nanopores contain an aqueous solution or a liquid; or (iii) the macropores contain gas or aerosol, and the micropores and / or the nanopores contain an aqueous solution or a liquid.

[0121] 8. A breathing simulator according to paragraph 7, wherein the aqueous solution or the liquid present in the micropores and / or the nanopores forms a water layer or a liquid layer covering a part or all of the surface of the macropores.

[0122] 9. A breathing simulator according to any of the preceding paragraphs, wherein the rigid porous foam contains a first connector capable of establishing a leak-proof connection with the breathing simulator.

[0123] 10. A breathing simulator according to any of the preceding paragraphs, wherein the rigid porous foam contains a second connector capable of connecting the rigid porous foam to an aqueous solution or liquid source.

[0124] 11. A breathing simulator according to any of the preceding paragraphs, wherein the rigid porous foam contains a third connector capable of connecting the rigid porous foam to a discharge port.

[0125] 12. A breathing simulator according to any of the preceding paragraphs, comprising one or more cavities or sockets or recesses or a combination of two or more thereof in the rigid porous foam, wherein the one or more cavities or sockets or recesses or a combination of two or more thereof are capable of accepting one or more sensing devices or probes or sampling devices or cell cultures.

[0126] 13. A breathing simulator according to paragraph 12, wherein the one or more cavities or sockets or recesses or a combination of two or more thereof contain the one or more sensing device probes or sampling devices or cell cultures.

[0127] 14. A breathing simulator according to any one of the preceding paragraphs, wherein the rigid porous foam comprises one or more bifurcated channels, suitably, wherein the bifurcated channel is bifurcated, more suitably, wherein the rigid porous foam forming the bifurcated channel contains micropores and / or nanopores.

[0128] 15. A breathing simulator according to any of the preceding paragraphs, wherein the interconnected network of macropores and micropores and / or nanopores comprises:

[0129] (i) pairs of macropores connected by a continuous channel formed by the macropores; and

[0130] (ii) pairs of micropores and / or nanopores, the pairs of micropores and / or nanopores being connected by a continuous channel formed by the micropores and / or the nanopores; and

[0131] (iii) micropores and / or nanopores, which are connected to any macropores through a continuous channel formed by the micropores and / or nanopores and the macropores.

[0132] 16. A breathing simulator according to any of the preceding paragraphs, wherein the radius of the macropore is between about 0.1 and about 0.4 mm, or between about 0.1 and about 0.3 mm, or between about 0.2 and about 0.4 mm, or between about 0.2 and about 0.3 mm, or the diameter is between about 200 µm and about 2000 µm, or the diameter is about 820 µm ± 150 µm.

[0133] 17. A breathing simulator according to any of the preceding paragraphs, wherein the radius of the micropores and / or the nanopores is between about 0.01 µm and about 50 µm in diameter, suitably, less than about 30 µm, or between about 0.25 µm and about 25 µm.

[0134] 18. A breathing simulator according to any of the preceding paragraphs, wherein the total surface area of ​​the rigid porous foam is at least about 70 square meters, suitably at least about 100 square meters.

[0135] 19. A breathing simulator according to any one of the preceding paragraphs, comprising at least two rigid porous foams, each of the at least two rigid porous foams having a different pore size distribution or each having a different porosity or each having a different material.

[0136] 20. A breathing simulator according to any one of paragraphs 7 to 19, wherein the absolute value of the negative pressure of the aqueous solution or the liquid below the surface across the micropores and / or the nanopores relative to the environment is greater than the absolute value of the negative pressure of the aqueous solution or the liquid below the surface across the macropores relative to the environment.

[0137] 21. A breathing simulator according to any one of the preceding paragraphs, wherein the rigid porous foam has a cylindrical shape or a disc shape or a rectangular parallelepiped shape.

[0138] 22. A breathing simulator according to paragraph 21, wherein the cylindrical or disc-shaped or cuboid-shaped rigid porous foam comprises radial walls made of a material different from that of the rigid porous foam.

[0139] 23. A breathing simulator according to paragraph 22, wherein the different material does not contain macropores, or wherein the different material is a synthetic material, preferably an epoxy resin or a metal or a combination thereof.

[0140] 24. A breathing simulator according to any of the preceding paragraphs, wherein a bridging structure contacts the rigid porous foam, preferably wherein a bridge is joined to the bridging structure, preferably wherein the bridge is flexible.

[0141] 25. A breathing simulator according to any of the preceding paragraphs, comprising a pump, and wherein the rigid porous foam is contained within the pump.

[0142] 26. A breathing simulator according to any of the preceding paragraphs, wherein the pump is a piston pump.

[0143] 27. Use of a rigid porous foam in a breathing simulator for simulating distal airways and alveoli, the rigid porous foam comprising an interconnected open-pore network having: (i) macropores; and (ii) micropores and / or nanopores.

[0144] 28. The use according to paragraph 27, wherein the rigid porous foam is: (i) a ceramic or metal rigid porous foam; or (ii) a ceramic and metal rigid porous foam.

[0145] 29. The use according to paragraph 28, wherein the rigid porous foam is made of: aluminum oxide or silicon carbide or oxygen-bonded silicon carbide or sintered silicon carbide or a combination of two or more thereof.

[0146] 30. The use according to any one of paragraphs 27 to 29, wherein the rigid porous foam contains walls and pillars, and wherein the pillars of the rigid porous foam contain micropores and / or nanopores, and wherein the walls of the macropores of the rigid porous foam are covered with the micropores and / or the nanopores that are open to the macropores.

[0147] 31. The use according to any of paragraphs 27 to 30, wherein the macropores are capable of conducting a gas or aerosol supplied to the rigid porous foam.

[0148] 32. The use according to any one of paragraphs 27 to 31, wherein the micropores and / or the nanopores are capable of: (i) conducting an aqueous solution or a liquid supplied to the rigid porous foam; and (ii) retaining the aqueous solution or the liquid within the micropores and / or the nanopores.

[0149] 33. The use according to any one of paragraphs 27 to 32, wherein: (i) the macropores contain a gas or an aerosol; or (ii) the micropores and / or the nanopores contain an aqueous solution or a liquid; or (iii) the macropores contain a gas or an aerosol, and the micropores and / or the nanopores contain an aqueous solution or a liquid.

[0150] 34. The use according to paragraph 33, wherein the micropores and / or the nanopores containing the aqueous solution or the liquid form a water layer or a liquid layer covering a part or the whole of the surface of the macropore.

[0151] 35. The use according to any one of paragraphs 27 to 34, wherein the rigid porous foam comprises one or more cavities or sockets or recesses or a combination of two or more thereof in the rigid porous foam, wherein the one or more cavities or sockets or recesses or a combination of two or more thereof are capable of receiving one or more sensing devices or probes or sampling devices or cell cultures.

[0152] 36. The use according to paragraph 35, wherein said one or more cavities or receptacles or recesses or a combination of two or more thereof contain said one or more sensing device probes or sampling devices or cell cultures.

[0153] 37. The use according to any one of paragraphs 27 to 36, wherein the rigid porous foam comprises one or more branched channels, suitably, wherein the branched channels are bifurcated, more suitably, wherein the branched channels are located in the micropores and / or the nanopores.

[0154] 38. The use according to any one of paragraphs 27 to 37, wherein the interconnected network of macropores and micropores and / or nanopores comprises:

[0155] (i) pairs of macropores connected by a continuous channel formed by the macropores; and

[0156] (ii) pairs of micropores and / or nanopores, the pairs of micropores and / or nanopores being connected by a continuous channel formed by the micropores and / or the nanopores; and

[0157] (iii) micropores and / or nanopores, which are connected to any macropores through a continuous channel formed by the micropores and / or nanopores and the macropores.

[0158] 39. The use according to any one of paragraphs 27 to 38, wherein the macropores have a radius between about 0.1 and about 0.4 mm, or between about 0.1 and about 0.3 mm, or between about 0.2 and about 0.4 mm, or between about 0.2 and about 0.3 mm, or a diameter between about 200 μm and about 2000 μm.

[0159] 40. The use according to any one of paragraphs 27 to 39, wherein the radius of the micropores and / or the nanopores is between about 0.01 µm and about 50 µm or between about 0.25 µm and about 25 µm in diameter.

[0160] 41. The use according to any of paragraphs 27 to 40, wherein the total surface area of ​​the rigid cellular foam is at least about 70 square meters, suitably at least about 100 square meters.

[0161] 42. The use according to any one of paragraphs 27 to 41, comprising at least two rigid porous foams, each of the at least two rigid porous foams having a different pore size distribution or each having a different porosity or each having a different material.

[0162] 43. The use according to any one of paragraphs 33 to 42, wherein the absolute value of the negative pressure of the aqueous solution or the liquid below the surface across the micropores and / or the nanopores relative to the environment is greater than the negative pressure of the aqueous solution or the liquid below the surface across the macropores relative to the environment.

[0163] 44. The use according to any one of paragraphs 27 to 43, wherein the rigid porous foam has a cylindrical shape, a disc shape, or a rectangular parallelepiped shape.

[0164] 45. The use according to paragraph 44, wherein the cylindrical or disc-shaped or cuboid-shaped rigid porous foam comprises radial walls made of a material different from that of the rigid porous foam.

[0165] 46. ​​The use according to paragraph 45, wherein the different material does not contain macropores, or wherein the different material is a synthetic material, preferably an epoxy resin or a metal or a combination thereof.

[0166] 47. The use according to any of paragraphs 27 to 46, wherein a bridging structure contacts the rigid porous foam, preferably wherein bridges are joined to the bridging structure, preferably wherein the bridges are flexible.

[0167] 48. The use according to any one of paragraphs 27 to 47, wherein the breathing simulator comprises a pump, and wherein the rigid porous foam is contained inside the pump.

[0168] 49. The use according to paragraph 48, wherein the pump is a piston pump.

[0169] 50. A method for determining the effects of a test atmosphere on simulated distal airways and alveoli of a mammalian respiratory tract, the method comprising:

[0170] (i) providing a breathing simulator according to any one of paragraphs 1 to 26;

[0171] (ii) contacting the breathing simulator with the test atmosphere; and

[0172] (iii) determining the effect of the test atmosphere on the simulated distal airways and the alveoli of the mammalian respiratory tract of the breathing simulator.

[0173] 51. Use of a breathing simulator according to any one of paragraphs 1 to 26 for determining the effects of a test atmosphere on simulated distal airways and alveoli of the respiratory tract of a mammal.

[0174] 52. A method of filling the micropores and / or nanopores of a rigid porous foam without filling the macropores with an aqueous solution or liquid, the rigid porous foam comprising an interconnected open-pore network having: (i) macropores; and (ii) micropores and / or nanopores, the method comprising:

[0175] (i) supplying the aqueous solution or the liquid to the rigid porous foam under negative pressure, the absolute value of which is greater than the negative pressure generated by the capillary action of the macropores but less than the negative pressure generated by the capillary action of the micropores and / or the nanopores; and

[0176] (ii) filling the micropores and / or the nanopores of the rigid porous foam with the aqueous solution or the liquid but not filling the macropores.

[0177] 53. A rigid porous foam used as a model of the distal airways and alveoli of the respiratory tract, the rigid porous foam comprising an interconnected open-pore network having: (i) macropores, the macropores containing a gas or an aerosol; and (ii) micropores and / or nanopores, the micropores and / or the nanopores containing an aqueous solution or a liquid, and wherein the micropores and / or the nanopores containing the aqueous solution or the liquid form a water layer or a liquid layer covering part or all of the surface of the macropores.

[0178] 54. The rigid cellular foam of paragraph 53, wherein the rigid cellular foam is: (i) a ceramic or metal rigid cellular foam; or (ii) a ceramic and metal rigid cellular foam.

[0179] 55. The rigid cellular foam of paragraph 53, wherein the rigid cellular foam is made of: aluminum oxide or silicon carbide or oxygen-bonded silicon carbide or sintered silicon carbide or a combination of two or more thereof.

[0180] 56. A rigid porous foam according to any one of paragraphs 53 to 55, wherein the rigid porous foam contains walls and pillars, and wherein the pillars of the rigid porous foam contain micropores and / or nanopores, and the walls of the macropores of the rigid porous foam are covered with the micropores and / or the nanopores that are open to the macropores.

[0181] 57. A rigid porous foam according to any one of paragraphs 53 to 56, comprising one or more cavities or sockets or recesses or a combination of two or more thereof, wherein the one or more cavities or sockets or recesses or a combination of two or more thereof are capable of accepting one or more sensing devices or probes or sampling devices or cell cultures.

[0182] 58. The rigid porous foam of paragraph 57, wherein the one or more cavities or sockets or recesses or a combination of two or more thereof contain the one or more sensing device probes or sampling devices or cell cultures.

[0183] 59. A rigid porous foam according to any one of paragraphs 53 to 58, wherein the rigid porous foam comprises one or more bifurcated channels, suitably wherein the bifurcated channels bifurcate, more suitably wherein the bifurcated channels are present within the micropores and / or the nanopores.

[0184] 60. The rigid cellular foam of any of paragraphs 53 to 59, wherein the interconnected network of macropores and micropores and / or nanopores comprises:

[0185] (i) pairs of macropores connected by a continuous channel formed by the macropores; and

[0186] (ii) pairs of micropores and / or nanopores, the pairs of micropores and / or nanopores being connected by a continuous channel formed by the micropores and / or the nanopores; and

[0187] (iii) micropores and / or nanopores, which are connected to any macropores through a continuous channel formed by the micropores and / or nanopores and the macropores.

[0188] 61. A rigid cellular foam according to any one of paragraphs 53 to 60, wherein the macropores have a radius of between about 0.1 to about 0.4 mm, or between about 0.1 to about 0.3 mm, or between about 0.2 to about 0.4 mm, or between about 0.2 to about 0.3 mm, or a diameter of between about 200 μm and about 2000 μm, suitably about 820 μm ± 150 μm in diameter.

[0189] 62. A rigid porous foam according to any one of paragraphs 53 to 61, wherein the radius of the micropores and / or the nanopores is between about 0.01 μm and about 50 μm in diameter, suitably less than about 30 μm in diameter, or between about 0.25 μm and about 25 μm.

[0190] 63. The rigid cellular foam of any of paragraphs 53 to 62, wherein the total surface area of ​​the rigid cellular foam is at least about 70 square meters, suitably at least about 100 square meters.

[0191] 64. The rigid porous foam of any one of paragraphs 53 to 63, comprising at least two rigid porous foams, each of the at least two rigid porous foams having a different pore size distribution or each having a different porosity or each having a different material.

[0192] 65. A rigid porous foam according to any one of paragraphs 53 to 64, wherein the absolute value of the negative pressure of the aqueous solution or the liquid below the surface across the micropores and / or the nanopores relative to the environment is greater than the absolute value of the negative pressure of the aqueous solution or the liquid below the surface across the macropores relative to the environment.

[0193] 66. The rigid cellular foam of any of paragraphs 53 to 65, wherein the rigid cellular foam has a cylindrical shape, a disc shape, or a cuboid shape.

[0194] 67. The rigid porous foam according to paragraph 66, wherein the cylindrical or disc-shaped or cuboid-shaped rigid porous foam comprises radial walls made of a different material than the rigid porous foam.

[0195] 68. The rigid cellular foam of paragraph 67, wherein the different material does not contain macropores, or wherein the different material is a synthetic material, preferably, epoxy or metal or a combination thereof.

[0196] 69. The rigid cellular foam of any of paragraphs 53 to 68, wherein a bridging structure contacts the rigid cellular foam, preferably wherein bridges are joined to the bridging structure, preferably wherein the bridges are flexible.

[0197] 70. The rigid cellular foam of any of paragraphs 53 to 69, wherein the rigid cellular foam is contained or mounted inside a pump, suitably the pump is a piston pump.

[0198] 71. A pump for displacing a volume of gas, comprising or containing a rigid porous foam inside the pump, wherein the rigid porous foam comprises an interconnected open-pore network having: (i) macropores; and (ii) micropores and / or nanopores as described herein, optionally wherein the rigid porous foam is connected to a port for receiving and outputting the gas.

[0199] 72. A system for determining the interaction between a test atmosphere and a simulated respiratory tract, the system comprising:

[0200] (a) a first pump, the first pump comprising:

[0201] (i) a chamber configured to contain a first volume of gas, the first volume of gas comprising a test atmosphere;

[0202] (ii) a first port adapted to receive and output a gas and comprising a valve for regulating gas flow through the first port, the valve being movable between an open position and a closed position, wherein in the open position the valve is open to a test atmosphere or ambient air;

[0203] (iii) a second port adapted to output and receive gas and comprising a valve for regulating gas flow through the second port, the valve being movable between an open position and a closed position;

[0204] (iv) a piston plate in the chamber, the piston plate comprising one or more apertures for the uptake or flow of gas into the chamber, wherein one or more of the apertures or each aperture comprises a valve movable between an open position and a closed position and capable of regulating the uptake or the flow of gas; and

[0205] (v) a motor for controlling the operation of the first pump;

[0206] (b) a second pump, wherein the second pump is as defined in paragraph 71;

[0207] (c) a connection structure operable to transfer the gas from the first pump to the second pump; and

[0208] (d) one or more openings located in the first pump or the second pump or a wall of the connecting structure or a combination of two or more thereof, the openings being capable of receiving a module for housing a matrix containing a cell culture medium and / or at least one microsensor for monitoring conditions in the chamber or for gas sampling or for gas characterization.

[0209] 73. A method for simulating the interaction between a test atmosphere and a simulated respiratory tract, the method comprising using a breathing simulator according to any one of paragraphs 1 to 26, or a rigid porous foam according to any one of paragraphs 53 to 70, or a pump according to paragraph 71 or a system according to paragraph 72.

[0210] 74. A use of a breathing simulator according to any one of paragraphs 1 to 26, or a rigid porous foam according to any one of paragraphs 53 to 70, or a pump according to paragraph 71, or a system according to paragraph 72 for simulating the interaction between a test atmosphere and a simulated respiratory tract, or for determining the effect of a test atmosphere on a cell culture contained in the rigid porous foam, the pump, or the system.

[0211] 75. A method for determining the effect of a test atmosphere on a cell culture contained in a simulated respiratory tract, the method comprising using a respiratory simulator according to any one of paragraphs 1 to 26, or a rigid porous foam according to any one of paragraphs 53 to 70, or a pump according to paragraph 71, or a system according to paragraph 72.

[0212] 76. A method for determining the effect of a test atmosphere on a cell culture contained in a simulated respiratory tract, the method comprising:

[0213] (a) providing a breathing simulator according to any one of paragraphs 1 to 26, or a rigid porous foam according to any one of paragraphs 53 to 70, or a pump according to paragraph 71, or a system according to paragraph 72, wherein the rigid porous foam, the pump, or the system contains a cell culture and / or at least one sensor in one or more modules; and

[0214] (b) comparing the cell culture and / or the at least one sensor before and / or after exposure to the test atmosphere, wherein differences between the cell culture and / or the at least one sensor before and / or after exposure of the cells and / or the at least one sensor to the test atmosphere indicate that the test atmosphere affects the cell culture and / or the at least one sensor.

[0215] 77. A device configured or adapted to perform a method according to any of paragraphs 50, 73, 75 or 76.

[0216] Any publication cited or described in this article provides relevant information disclosed before the filing date of this application. Statements herein should not be interpreted as admitting that the inventor loses the qualification prior to such disclosure. All publications mentioned in the above specification are incorporated herein by reference. Without departing from the scope and spirit of the present invention, various modifications and changes of the present invention will be apparent to those skilled in the art. Although the present invention has been described in conjunction with specific preferred embodiments, the claimed invention should not be unduly limited to such specific embodiments. In fact, various modifications of the described modes for carrying out the present invention are apparent to those skilled in the art and are intended to fall within the scope of the following claims.

Claims

1. A breathing simulator comprising a rigid porous foam comprising an interconnected open-pore network having: (i) macropores; and (ii) micropores and / or nanopores.

2. A breathing simulator according to claim 1, wherein the rigid porous foam is: (i) a ceramic or metal rigid porous foam; or (ii) a ceramic and metal rigid porous foam; preferably, Wherein the rigid porous foam is made of: alumina or silicon carbide or oxygen-bonded silicon carbide or sintered silicon carbide or a combination of two or more thereof.

3. A breathing simulator according to claim 1 or claim 2, wherein: (i) the macropores contain a gas or an aerosol; or (ii) the micropores and / or the nanopores contain an aqueous solution or a liquid; or (iii) the macropores contain a gas or an aerosol, and the micropores and / or the nanopores contain an aqueous solution or a liquid. 4 . The breathing simulator according to claim 3 , wherein the micropores and / or the nanopores containing the aqueous solution or the liquid form a water layer or a liquid layer covering a part or the whole of the surface of the macropore.

5. A breathing simulator according to any of the preceding claims, wherein the rigid porous foam comprises one or more cavities or sockets or recesses or a combination of two or more thereof, preferably wherein the one or more cavities or sockets or recesses or a combination of two or more thereof contain one or more sensing devices or probes or sampling devices or cell cultures.

6. A breathing simulator according to any one of the preceding claims, comprising at least two rigid porous foams, each having a different pore size distribution or each having a different porosity or each having a different material.

7. A breathing simulator according to any one of the preceding claims, wherein the breathing simulator comprises a pump, and wherein the rigid porous foam is contained or mounted inside the pump, preferably wherein the pump is a piston pump.

8. Use of a rigid porous foam of a breathing simulator for simulating distal airways and alveoli, the rigid porous foam comprising an interconnected open-pore network having: (i) macropores; and (ii) micropores and / or nanopores.

9. The use according to claim 8, wherein the rigid porous foam is: (i) a ceramic or metal rigid porous foam; or (ii) a ceramic and metal rigid porous foam; preferably, Wherein the rigid porous foam is made of: alumina or silicon carbide or oxygen-bonded silicon carbide or sintered silicon carbide or a combination of two or more thereof.

10. A method for determining the effect of a test atmosphere on simulated distal airways and alveoli of a respiratory tract, the method comprising: (i) providing a breathing simulator according to any one of claims 1 to 7; (ii) contacting the breathing simulator with the test atmosphere; and (iv) determining the effect of the test atmosphere on the simulated distal airways and alveoli of the respiratory tract.

11. A rigid porous foam for use in a model of distal airways and alveoli of the respiratory tract, the rigid porous foam comprising an interconnected open-pore network having: (i) macropores, the macropores containing a gas or aerosol; and (ii) micropores and / or nanopores, the micropores and / or the nanopores containing an aqueous solution or a liquid, and wherein the micropores and / or the nanopores containing the aqueous solution or the liquid form a water layer or a liquid layer covering part or all of the surface of the macropores.

12. The rigid porous foam according to claim 11, wherein the rigid porous foam is: (i) a ceramic or metal rigid porous foam; or (ii) a ceramic and metal rigid porous foam; preferably, Wherein the rigid porous foam is made of: alumina or silicon carbide or oxygen-bonded silicon carbide or sintered silicon carbide or a combination of two or more thereof.

13. A rigid cellular foam according to claim 11 or claim 12, wherein: (i) the macropores contain a gas or an aerosol; or (ii) the micropores and / or the nanopores contain an aqueous solution or a liquid; or (iii) the macropores contain a gas or an aerosol, and the micropores and / or the nanopores contain an aqueous solution or a liquid.

14. The rigid porous foam according to any one of claims 11 to 13, wherein the rigid porous foam comprises one or more cavities or sockets or recesses or a combination of two or more thereof, preferably, wherein the one or more cavities or sockets or recesses or a combination of two or more thereof contain one or more modules for containing or storing cell culture medium and / or at least one microsensor for monitoring conditions in the chamber or for gas sampling or for gas characterization.

15. The rigid cellular foam according to any one of claims 11 to 14, wherein the rigid cellular foam is contained or mounted inside a pump, preferably wherein the pump is a piston pump.

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