Atomizer and mesh therefor

Abstract

To provide a mesh for an atomizer assembly.SOLUTION: A mesh (1) for an atomizer assembly (50) is provided, the mesh including a first surface (3) and a second surface (4), and a plurality of nozzles (2) extending between the first surface (3) and the second surface (4). The first surface (3) is at least partially coated with a hydrophilic coating or the second surface (4) is at least partially coated with a hydrophobic coating. The nozzles (2) define an inner surface (5) and the inner surface (5) is at least partially coated with a hydrophilic coating.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a mechanical atomizer having a vibrating mesh, more particularly to an atomizer having a passive mesh. [Background technology]

[0002] The aerosol generating device having an atomizer and a passive mesh includes a liquid source (e.g., a liquid cartridge), a power source (e.g., a battery), and an atomizer. The atomizer includes a vibrator system (e.g., piezoelectric), a vibrating element, a mesh having multiple nozzles, and a liquid chamber surrounded by the mesh and the vibrating element.

[0003] In a passive mesh system, the mesh is an element that is not actuated and is not designed to vibrate. The vibrating element is actuated by the vibrator system such that the vibrating element vibrates substantially transversely to a plane defined by the vibrating element. Liquid from the liquid chamber is in contact with both the vibrating element and the mesh. The vibration of the vibrating element periodically pushes the liquid, which moves the liquid towards or away from the mesh. By moving the liquid towards the mesh, the liquid is pushed through a nozzle provided in the mesh. Subsequently, by moving the liquid away from the mesh, droplets are formed. Hence, the mesh generates an aerosol.

[0004] Currently available atomizers cannot produce droplets with a diameter less than 3 μm. If the viscosity of the liquid is significantly higher than that of water (e.g., 10 times higher than that of water), droplets with a diameter less than 5 μm cannot be produced.

[0005] To improve nicotine delivery, the droplet size should be less than 3 μm. A reduction in droplet size is not achieved by simply reducing the nozzle diameter below 3 μm, as reducing the nozzle diameter does not usually result in the desired droplet diameter. Summary of the Invention

[0006] A mesh for an atomizer assembly is provided. The mesh may include a first surface and a second surface. The plurality of nozzles may extend between the first surface and the second surface. The first surface may be at least partially coated with a hydrophilic coating, or the second surface may be at least partially coated with a hydrophobic coating.

[0007] According to a first aspect of the present invention, there is provided a mesh for an atomizer assembly. The mesh comprises a first surface, a second surface, and a plurality of nozzles extending between the first and second surfaces. The first surface is at least partially coated with a hydrophilic coating or the second surface is at least partially coated with a hydrophobic coating. The nozzles define an inner surface, the inner surface being at least partially coated with a hydrophilic coating.

[0008] As used herein, the term "droplet diameter" refers to the diameter determined as the mass median aerodynamic diameter (MMAD), which is used to mean the diameter of a sphere of unit density having the same aerodynamic properties as the median mass droplet of the aerosol.

[0009] The mass median aerodynamic diameter (MMAD) of droplets generated using a mesh according to the first aspect of the invention may be less than 3 μm, such as from about 0.1 μm to about 3 μm. The MMAD of droplets generated using a mesh according to the first aspect of the invention may be from about 0.1 μm to 2.8 μm, such as from 0.1 μm to 2.5 μm or from 0.1 μm to 2 μm. The MMAD of droplets generated using a mesh according to the first aspect of the invention may be from about 0.6 μm to 1 μm, such as 0.8 μm or about 0.8 μm. The desired droplet size of droplets generated using a mesh according to the first aspect of the invention may be any of the MMADs mentioned above.

[0010] The aerosol-forming liquid used for aerosol generation in an atomizer comprising a mesh according to the first aspect of the invention may have a viscosity in the range of 1 mPas (milliPascal second, mPa·s) to 100 mPas. The liquid may have a viscosity of 15 mPas to 90 mPas, for example 17 mPas to 86 mPas. A liquid having a viscosity as mentioned above allows a wider range of flavours and liquid compositions to be used.

[0011] "Mesh" as used herein describes an element suitable for use in an atomizer assembly. A mesh is a flat element that defines two surfaces and a number of nozzles through which a fluid (e.g., liquid) can travel from one surface to the other. By flat element, we mean that the mesh has one of its dimensions (thickness) that is significantly smaller than the other two dimensions. Thus, the mesh defines two surfaces.

[0012] The mesh may be square in shape. The sides of the square may be about 3 mm long. The sides of the square may be about 2 mm long. The mesh may be circular. The diameter of the circle may be about 2 mm. The thickness of the mesh may be between 10 μm and 0.5 mm. The thickness of the mesh must be selected with respect to the pressure inside the device, the required durability of the mesh, and the required length of the nozzle. A thicker mesh is more durable, i.e. it can withstand more mechanical stress. However, the thicker the mesh, the more the pressure inside the device and on the mesh increases.

[0013] The first surface may be at least partially coated with a hydrophilic coating. The second surface may be at least partially coated with a hydrophobic coating. In this context, "at least partially" means that a certain percentage of the surface area is covered with the coating, the percentage being less than 100%. For example, at least 20% of the surface is coated, or at least 50% of the surface is coated, or at least 80% of the surface is coated, or at least 95% of the surface is coated. In one embodiment, the entire surface is coated.

[0014] The mesh is provided with a plurality of nozzles. As used herein, "nozzle" describes a through hole that allows a first surface to be in fluid communication with a second surface. The nozzle extends through the thickness of the material from which the mesh is made and has a first opening at the first surface and a second opening at the second surface.

[0015] The nozzles may be tubular. The nozzle openings may be circular, elliptical, or any other suitable shape. The first opening of each nozzle may be wider than the second opening of the nozzle. The nozzles may taper towards the second opening. The nozzles may be triangular in cross section. The nozzles may be cylindrical, parabolic, or hyperbolic. The nozzles may be rotationally symmetric.

[0016] The second opening of the nozzle may have a diameter of 0.1 μm to 10 μm. The second opening of the nozzle may have a diameter of 1 μm to 10 μm. The second opening of the nozzle may have a diameter of 2.5 μm to 4 μm. The diameter range of 2.5 μm to 4 μm is preferred because this diameter range allows for the production of droplets less than 3 μm.

[0017] The nozzles may be provided evenly on the mesh in a periodic or quasi-periodic pattern. The nozzles may be provided in separate regions that are periodically or quasi-periodically distributed on the mesh, each of the separate regions having one or more periodic or quasi-periodic mesh patterns. The nozzles may be randomly distributed on the mesh. If the nozzles are randomly distributed, there may be a minimum guaranteed number of nozzles per unit area of ​​the mesh.

[0018] If the nozzles are provided in separate regions, only the regions with the nozzles may be coated with a hydrophilic and / or hydrophobic coating, while the regions without the nozzles may remain uncoated.

[0019] The nozzle defines an interior surface between the first and second openings. The interior surface may be coated with a hydrophilic material. The hydrophilic material coating the interior surface of the nozzle may be the same material as the material coating the first surface. The hydrophilic material coating the interior surface of the nozzle may be a different material than the material coating the first surface.

[0020] Hydrophobic surfaces have a contact angle θ greater than 90 degrees. Hydrophobic surfaces typically have a contact angle θ between 90 degrees and 120 degrees (droplets bead up). In contrast to hydrophobic surfaces, on hydrophilic surfaces, water droplets spread farther and the contact angle θ is very small. On these surfaces, water droplets slide rather than roll.

[0021] The hydrophobic and / or hydrophilic coatings are selected for their stability to ensure that there is no degradation of the coating due to increased temperature or mechanical stress, and for example, to ensure that there is no chemical reaction with tobacco, nicotine-based liquids and aerosols generated in the device.

[0022] The coating may be applied by chemical surface modification or physical deposition (such as vacuum deposition and plasma surface treatment). The coating may be applied to the underlying base material by methods known in the art for depositing thin films. Chemical or physical vapor deposition may be used. For example, the coating material may be sprayed directly onto the surface of the material to be coated, or a dip coating of the material to be coated may be applied. More durable surface treatments are, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), self-assembled monolayers (SAMs), sol-gel processes and other deposition processes suitable for thin film coatings.

[0023] The hydrophobic coating may include either polyurethane (PU) or a superhydrophobic metal (such as a microporous metal or metal mesh). The microporous metal or metal mesh may be functionalized with carbon chains to render the microporous metal or metal mesh superhydrophobic. Exemplary superhydrophobic metals include copper and aluminum.

[0024] The hydrophobic coating may be at least partially formed of either polyurethane (PU) or a superhydrophobic metal layer (such as a microporous metal or metal mesh). The microporous or mesh metal may be, for example, copper or aluminum, and may be functionalized with carbon chains to make it superhydrophobic. In other words, the hydrophobic metal layer may be a microporous metal functionalized with carbon chains to make it superhydrophobic, or a mesh metal functionalized with carbon chains to make it superhydrophobic.

[0025] The hydrophilic coating may be at least partially formed of polyamide, polyvinyl acetate (PVAc), cellulose acetate or cotton. The hydrophilic coating may be at least partially formed of a hydrophilic oxide, such as one or more of the following group: SiO 2 ,aluminum 2 O 3 , TiO 2 , Ta 2 O 5 .

[0026] The mesh may be made of silicon. In the manufacture of the mesh, silicon-on-insulator wafers may be used. In an example manufacturing process of the mesh, the silicon is cleaned with an acid-based clean, such as an RCA clean. https: / / en.wikipedia.org / wiki / RCA_clean Hence, the surface is oxidized and thus becomes hydrophilic. In another exemplary manufacturing process, the silicon may be thermally oxidized and coated with a thin oxide layer, such as one or more of the following: SiO 2 , Al 2 O 3 , TiO 2 , HfO 2 or other metal oxides or non-metal oxides. Silicon may also be coated by sputter coating, atomic layer deposition (ALD), or molecular layer deposition (MVD).

[0027] An atomizer using a mesh according to the present invention comprises a mesh, an elastic element, an actuator, and a cavity between the mesh and the elastic element. The cavity contains a liquid to be atomized. The mesh is positioned within the atomizer such that, when positioned within the atomizer, a first surface faces the cavity and a second surface faces the exterior of the cavity.

[0028] The atomizer assembly may then be actuated. The atomizer may be actuated at a resonant frequency. The resonant frequency is a function of one or more of the following: viscosity of the e-liquid (which can be decreased by increasing its temperature above room temperature to below 100° C.), surface tension of the e-liquid, nozzle diameter and shape, mesh thickness or stiffness, rate of droplet ejection, amplitude of actuation, mechanical properties of the atomizer assembly. The resonant frequency may be calculated based on a combination of the above factors.

[0029] Using a mesh as described above, it is possible to achieve the formation of droplets whose diameter is typically less than 3 μm. To reduce the diameter of the droplets formed, the viscosity of the e-liquid can be reduced by increasing its temperature. To reduce the diameter of the droplets formed, a suitable operating frequency can be used, for example a resonant frequency as described above.

[0030] The coating aids in droplet formation as follows: The hydrophilic coating on the first surface and the inner surface of the nozzle facilitates movement of the liquid through the nozzle. The hydrophilic coating helps the liquid enter and move through the nozzle. When the liquid reaches the second surface, the hydrophobic coating helps the liquid leave the second opening of the nozzle (i.e., away from the nozzle exit).

[0031] Using a mesh as described above makes it possible to achieve droplet diameters of less than 3 μm.

[0032] According to a second aspect of the present invention there is provided an atomiser assembly for an aerosol generating device, the atomiser assembly comprising a mesh as described above in relation to the first aspect.

[0033] The assembly may further comprise an elastically deformable element, a recess positioned between the mesh element and the elastically deformable element, a liquid inlet for providing a supply of liquid to be atomized to the recess, and an actuator arranged to vibrate the elastically deformable element.

[0034] According to a third aspect of the present invention there is provided an aerosol generating device comprising an atomiser assembly as described in relation to the second aspect of the present invention.

[0035] Specific embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0036] [Figure 1a] FIG. 1a is a schematic diagram of one embodiment of a mesh according to the present invention. [Figure 1b] FIG. 1b is a schematic diagram of one embodiment of a mesh according to the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view of the mesh. [Diagram 3] FIG. 3 is a schematic diagram of a mesh based atomizer assembly. [Figure 4] FIG. 4 is a schematic diagram of an aerosol generating device using a mesh. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Figures 1a, 1b and 2 show examples of meshes 1 according to the invention. The mesh in figure 1a is circular and comprises a centre with nozzles 2 and a rim without nozzles. Figure 1b shows a square mesh 1 with nozzles 2. The shape of the mesh and whether a rim is provided depends on the atomiser or on the way the mesh is held in the atomiser.

[0038] The mesh comprises a number of nozzles 2. As shown diagrammatically in Figure 2, the nozzles 2 are triangular and their first openings 6 are larger than their second openings 7. The mesh 1 has a first surface 3 that is positioned towards a cavity 62 containing the liquid when positioned in the atomizer assembly 50, and a second surface 4 that is positioned away from the cavity 62 containing the liquid when positioned in the atomizer assembly.

[0039] Each of the nozzles 2 comprises a first opening 6 through which liquid enters the nozzle 2, a second opening 7 through which liquid exits the nozzle 2, and an inner surface 5 connecting the first opening 6 with the second opening 7.

[0040] The first surface 3 is coated with a hydrophilic coating (not shown), which may be any one of the following: polyamide, polyvinyl acetate, cellulose acetate, or cotton.

[0041] The second surface 4 is coated with a hydrophobic coating. The hydrophobic coating comprises one of a layer of polyurethane (PU) or a superhydrophobic metal, such as a microporous metal or metal mesh. The microporous metal or metal mesh comprises copper or aluminum functionalized with carbon chains.

[0042] The inner surface 5 of each nozzle is also coated with a hydrophilic coating, which is the same as the coating on the first surface.

[0043] Figure 3 shows a perspective cross-sectional view of an atomizer assembly 50 comprising the mesh 1 of Figures 1 and 2. The mesh 1 is received within a mesh housing 52. The atomizer assembly 50 also comprises an elastically deformable element 54 and an actuator 56 arranged to vibrate the elastically deformable element 54. The actuator 56 is a piezoelectric actuator.

[0044] The atomizer assembly 50 also includes a preloaded element 58 arranged to compress the actuator 56 between the preloaded element 58 and the elastically deformable element 54. The preloaded element 58, the actuator 56, and the elastically deformable element 54 are arranged within an actuator housing 60. The actuator housing 60 is attached to the mesh housing 52 and defines a cavity 62 between the mesh housing 52 and the elastically deformable element 54. The actuator housing 60 defines a liquid inlet 64 for providing a supply of liquid to be atomized to the cavity 62.

[0045] In use, liquid to be atomized is supplied to the cavity 62 through the liquid inlet 64. The actuator 56 vibrates the elastically deformable element 54 to force at least a portion of the liquid in the cavity 62 through the channel 14 and the nozzle 2 of the mesh 1. The liquid forced through the nozzle 18 of the mesh 1 forms droplets. The momentum of the liquid forced through the nozzle 18 to form droplets carries the droplets away from the mesh 1. Thus, in use, the atomizer assembly 50 generates an aerosol comprising droplets of liquid expelled through the mesh 1.

[0046] The atomizer may be operated at a resonant frequency. The resonant frequency is a function of one or more of the following: viscosity of the e-liquid (which can be reduced by increasing its temperature above room temperature to below 100° C.), surface tension of the e-liquid, nozzle diameter and shape, mesh thickness or stiffness, rate of droplet ejection, amplitude of actuation, mechanical properties of the atomizer assembly. The resonant frequency may be calculated based on a combination of the above factors.

[0047] 4 shows a cross-sectional view of an aerosol generation system 70 according to an embodiment of the present invention. The aerosol generation system 70 comprises an aerosol generating device 72 and a liquid reservoir 74.

[0048] The aerosol generating device 72 comprises a housing 76 comprising a first housing portion 78 and a second housing portion 80. A controller 82 and a power source 84 comprising a battery are positioned within the first housing portion 78. A mouthpiece 85 defining a mouthpiece channel 87 is connectable to the second housing portion 80.

[0049] The second housing portion 80 defines a liquid storage chamber 86 for receiving the liquid reservoir 74. The first housing portion 78 is removable from the second housing portion 80 to allow replacement of the liquid reservoir 74.

[0050] The aerosol generating device 72 also includes a device connector 88 positioned within the liquid storage chamber 86 for engagement with a reservoir connector 90 forming part of the liquid reservoir 74 .

[0051] The aerosol generation device 72 includes the atomizer assembly 50 of FIG. 3 positioned within the second housing portion 80. The liquid inlet 64 of the atomizer assembly 50 is in fluid communication with the device connector 88. The mesh 1 of the atomizer assembly 50 is positioned within the aerosol chamber 92 defined by the second housing portion 80.

[0052] The liquid reservoir 74 comprises a container 94 and a liquid aerosol-forming substrate 96 positioned within the container 94. When the reservoir connector 90 is engaged with the device connector 88, the liquid aerosol-forming substrate 96 from the liquid reservoir 74 is provided through the reservoir connector 90, the device connector 88, and the liquid inlet 64 of the atomizer assembly 50 to the cavity 62 of the atomizer assembly 50.

[0053] When the first housing part 78 is connected to the second housing part 80, the controller 82 controls the supply of power from the power source 84 to the actuator 56 to eject droplets of the liquid aerosol-forming substrate 96 from the mesh 1 into the aerosol chamber 92.

[0054] The second housing portion 80 defines an air inlet 98 and an air outlet 100, each in fluid communication with the aerosol chamber 92. During use, a user draws on the mouthpiece 85 to draw air through the air inlet 98 and into the aerosol chamber 92. The air flows through the aerosol chamber 92, where droplets of the liquid aerosol-forming substrate 96 expelled from the mesh 1 are entrained in the airflow to form an aerosol. The aerosol flows out of the aerosol chamber 92 through the air outlet 100 and is delivered to the user through the mouthpiece channel 87.

[0055] The aerosol generation device 72 also includes an airflow sensor 102 positioned within the aerosol chamber 92. The airflow sensor 102 is arranged to provide a signal to the controller 82 indicative of the user sucking on the mouthpiece 85. The controller 82 is arranged to provide power from the power source 84 to the actuator 56 of the atomizer assembly 50 only when the controller receives a signal from the airflow sensor 102 indicative of the user sucking on the mouthpiece 85.

Claims

1. 1. An atomizer assembly for an aerosol generating device, the atomizer assembly comprising:

1. An atomizer assembly comprising: a mesh comprising a first surface, a second surface, and a plurality of nozzles extending between the first and second surfaces, the first surface being at least partially coated with a hydrophobic coating, the second surface being at least partially coated with a hydrophilic coating, the nozzles defining an interior surface, the interior surface being at least partially coated with a hydrophilic coating, each nozzle defining a first opening in the first surface and a second opening in the second surface, the first opening being wider than the second opening, each nozzle continuously tapering from the first opening to the second opening, and the atomizer assembly configured to operate at a resonant frequency.

2. 10. The atomizer assembly of claim 1, wherein the first surface is at least partially coated with a hydrophilic coating.

3. 3. The atomizer assembly of claim 1 or claim 2, wherein the entire surface of the first surface is coated with a hydrophilic coating, or the entire surface of the second surface is coated with a hydrophobic coating, or the entire surface of the first surface is coated with a hydrophilic coating and the entire surface of the second surface is coated with a hydrophobic coating.

4. The atomizer assembly of any one of claims 1 to 3, wherein the hydrophobic coating comprises polyurethane (PU), or a superhydrophobic metal layer, or a combination of both.

5. 5. The atomizer assembly of claim 4, wherein the superhydrophobic metal layer comprises a microporous metal functionalized with carbon chains or a metal mesh functionalized with carbon chains.

6. The atomizer assembly of any one of claims 1 to 3, wherein the hydrophilic coating comprises at least one of the following: oxides, 3 polyamide, polyvinyl acetate, cellulose acetate, cotton.

7. The atomizer assembly of any one of claims 1 to 6, wherein the hydrophilic coating comprises at least one of the following: SiO 2 , Al 2 O 3 , TiO 2 , Ta 2 O 5 , HfO 2 .

8. The atomizer assembly of any one of claims 1 to 7, wherein the mesh is made of silicone.

9. A mesh for an atomizer assembly according to any one of claims 1 to 8, wherein said second openings have a diameter of between 2.5 μm and 4 μm.

10. The atomizer assembly of any one of claims 1 to 9, wherein the mesh is flat.

11. the assembly comprising: an elastically deformable element; a recess positioned between the mesh element and the elastically deformable element; a liquid inlet for providing a supply of liquid to be atomized into said cavity; An atomizer assembly according to any preceding claim, further comprising: an actuator arranged to vibrate the resiliently deformable element.

12. 12. The atomizer assembly of claim 11, wherein the mesh is positioned such that the first surface of the mesh faces the recess and the second surface of the mesh faces an exterior of the atomizer assembly.

13. An atomizer assembly according to any one of the preceding claims, wherein the liquid has a viscosity of from 15 mPas to 90 mPas.

14. The atomizer assembly of any one of claims 1 to 13, wherein the mesh has a thickness of from 10 μm to 0.5 mm.

15. The atomizer assembly of any one of claims 1 to 14, wherein the atomizer assembly is for delivering nicotine.

16. An aerosol generating device comprising an atomizer assembly according to any one of claims 1 to 15.

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