Atomizer and mesh therefor

Abstract

A mesh (1) for an atomizer assembly (50) having a first surface (3), 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), which is at least partially coated with a hydrophilic coating. [Selected figure] Figure 3

Description

Technical Field

[0001] The present invention relates to a mechanical atomizer having a vibrating mesh. More specifically, the present invention relates to an atomizer having a passive mesh.

Background Art

[0002] An 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 a plurality of 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 operated to vibrate and is not designed to vibrate. The vibrating element is operated by the vibrator system such that the vibrating element vibrates in a direction substantially transverse to the plane defined by the vibrating element. The 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 the nozzles provided in the mesh. Thereafter, by moving the liquid away from the mesh, droplets are formed. Therefore, the mesh generates an aerosol.

[0004] Currently available atomizers cannot generate droplets having a diameter of less than 3 μm. When the viscosity of the liquid is significantly higher than the viscosity of water (e.g., 10 times higher than the viscosity of water), droplets having a diameter of less than 5 μm cannot be generated.

[0005] To improve nicotine delivery, the droplet size should be less than 3 μm. Reducing the diameter of the nozzle usually does not result in the desired droplet diameter, so reducing the droplet size cannot be achieved by simply reducing the nozzle diameter to less than 3 μm.

Summary of the Invention

[0006] A mesh for an atomizer assembly is provided. The mesh may comprise a first surface and a second surface. A 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, a mesh for an atomizer assembly is provided. The mesh comprises a first surface, a second surface, and a plurality of nozzles extending between the first surface and the second surface. 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, and the inner surface is at least partially coated with a hydrophilic coating.

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

[0009] The mass median aerodynamic diameter (MMAD) of droplets generated using a mesh according to the first aspect of the present invention can be less than 3 μm, for example, from about 0.1 μm to less than about 3 μm. The MMAD of droplets generated using a mesh according to the first aspect of the present invention can be from about 0.1 μm to 2.8 μm, for example, 0.1 μm to 2.5 μm or 0.1 μm to 2 μm. The MMAD of droplets generated using a mesh according to the first aspect of the present invention can be from about 0.6 μm to 1 μm, for example, 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 present invention can be any of the above-described MMADs.

[0010] The aerosol-forming liquid used for aerosol generation in an atomizer comprising a mesh according to the first aspect of the present invention can have a viscosity in the range of 1 mPas (millipascal second, mPa·s) to 100 mPas. The liquid can have a viscosity of 15 mPas to 90 mPas, for example, 17 mPas to 86 mPas. Liquids having a viscosity as described above enable the use of a wider range of flavoring agents and liquid compositions.

[0011] As used herein, "mesh" describes an element suitable for use in an atomizer assembly. A mesh is a flat element that defines two surfaces and a plurality of nozzles through which a fluid (e.g., a liquid) can move from one surface to the other. By flat element is meant 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 side of the square may be about 3 mm in length. The side of the square may be about 2 mm in length. The mesh may be circular. The diameter of the circle may be about 2 mm. The thickness of the mesh may be from 10 μm to 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., can withstand mechanical stress. However, the thicker the mesh, the greater the pressure in the device and the pressure applied to the mesh.

[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 specific percentage of the surface area is coated with that coating, and the percentage is 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, a "nozzle" describes a through-hole that enables the first surface to be in fluid communication with the second surface. The nozzle extends through the thickness of the material of which the mesh is made and has a first opening on the first surface and a second opening on the second surface.

[0015] The nozzle may be tubular. The opening of the nozzle 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 nozzle may taper towards the second opening. The nozzle may have a triangular cross-section. The nozzle may be cylindrical, parabolic, or hyperbolic. The nozzle 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. A diameter range of 2.5 μm to 4 μm is preferred because this diameter range enables the generation 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 distributed periodically or quasi-periodically on the mesh, and each of the individual regions may have one or more periodic or quasi-periodic mesh patterns. The nozzles may be randomly distributed on the mesh. When the nozzles are randomly distributed, there may be a minimum guaranteed number of nozzles per unit area of the mesh.

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

[0019] The nozzle defines an inner surface between the first opening and the second opening. The inner surface can be coated with a hydrophilic material. The hydrophilic material coating the inner surface of the nozzle may be the same material as the material coating the first surface. The hydrophilic material coating the inner surface of the nozzle may be a different material from the material coating the first surface.

[0020] The hydrophobic surface has a contact angle θ greater than 90 degrees. The contact angle θ of the hydrophobic surface is typically between 90 degrees and 120 degrees (the droplet becomes spherical). In contrast to hydrophobicity, on a hydrophilic surface, the water droplet spreads far and the contact angle θ is very small. On these surfaces, the water droplet does not roll but moves smoothly.

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

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

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

[0024] The hydrophobic coating can be at least partially formed of either polyurethane (PU) or a superhydrophobic metal layer (such as microporous metal or metal mesh). The microporous metal 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 microporous metal functionalized with carbon chains to make it superhydrophobic, or 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 hydrophilic oxides, such as, for example, one or more of the following group: SiO2, aluminum2O3, TiO2, Ta2O5.

[0026] The mesh may be made of silicon. In the manufacture of the mesh, a silicon-on-insulator wafer may be used. In an example of the mesh manufacturing process, the silicon is cleaned with an acid-based cleaning such as RCA cleaning. https: / / en.wikipedia.org / wiki / RCA_clean Therefore, 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: SiO2, Al2O3, TiO2, HfO2, or other metal oxides or non-metal oxides. The silicon may also be coated by sputter coating, atomic layer deposition (ALD), or molecular layer deposition (MVD).

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

[0028] Thereafter, the atomizer assembly may be operated. The atomizer may be operated at a resonance frequency. The resonance frequency is a function of one or more of the following: the viscosity of the e-liquid (which can be reduced by raising its temperature to a temperature higher than room temperature and lower than 100°C), the surface tension of the e-liquid, the diameter and shape of the nozzle, the thickness or stiffness of the mesh, the droplet ejection rate, the amplitude of operation, the mechanical properties of the atomizer assembly. The resonance 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 typically less than 3 μm in diameter. To reduce the diameter of the droplets formed, the viscosity of the e-liquid can be decreased by increasing its temperature. To reduce the diameter of the droplets formed, an appropriate operating frequency can be used, such as the resonance 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 facilitate the movement of the liquid through the nozzle. The hydrophilic coating helps the liquid enter the nozzle and move through it. When the liquid reaches the second surface, the hydrophobic coating helps the liquid leave the second opening of the nozzle (i.e., the nozzle outlet).

[0031] Using a mesh as described above enables achieving a droplet diameter of less than 3 μm.

[0032] According to a second aspect of the present invention, an atomizer assembly for an aerosol generating device is provided. The atomizer assembly comprises 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 the 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, an aerosol generating device is provided. The aerosol generating device comprises an atomizer assembly as described above in relation to the second aspect of the present invention.

[0035] Here, specific embodiments of the present invention will be described by way of illustration only with reference to the accompanying drawings.

Brief Description of the Drawings

[0036]

Fig. 1a

Fig. 1b

Fig. 2

Fig. 3

Fig. 4

Mode for Carrying Out the Invention

[0037] Figures 1a, 1b and 2 show examples of the mesh 1 according to the present invention. The mesh of Figure 1a is circular and comprises a central portion having a nozzle 2 and a rim without a nozzle. Figure 1b shows a square mesh 1 having a nozzle 2. Whether the shape of the mesh and the rim are provided depends on the atomizer or on the way the mesh is held within the atomizer.

[0038] The mesh comprises a plurality of nozzles 2. As schematically shown 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 which, when positioned within the atomizer assembly 50, is positioned towards a recess 62 containing liquid, and a second surface 4 which, when positioned within the atomizer assembly, is positioned away from the recess 62 containing liquid.

[0039] Each of the nozzles 2 comprises a first opening 6 through which liquid passes into the nozzle 2, a second opening 7 through which liquid passes out of the nozzle 2, and an inner surface 5 connecting the first opening 6 to the second opening 7.

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

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

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

[0043] Figure 3 shows a perspective cross-sectional view of an atomizer assembly 50 comprising the mesh 1 of FIGS. 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 comprises a preloading element 58 arranged to compress the actuator 56 between the preloading element 58 and the elastically deformable element 54. The preloading 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 recess 62 between the mesh 1 and the elastically deformable element 54. The actuator housing 60 defines a liquid inlet 64 for providing a supply of the liquid to be atomized to the recess 62.

[0045] In use, the liquid to be atomized is supplied through the liquid inlet 64 to the recess 62. The actuator 56 vibrates the elastically deformable element 54 to push at least a portion of the liquid within the recess 62 through the channels 14 and the nozzles 2 of the mesh 1. The liquid pushed through the nozzles 18 of the mesh 1 forms droplets. The momentum of the liquid pushed through the nozzles 18 to form the droplets carries the droplets away from the mesh 1. Thus, in use, the atomizer assembly 50 generates an aerosol containing droplets of the liquid discharged through the mesh 1.

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

[0047] Figure 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 includes an aerosol generator 72 and a liquid reservoir 74.

[0048] The aerosol generator 72 includes a housing 76 having a first housing portion 78 and a second housing portion 80. A controller 82 and a power supply 84 including 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 reservoir chamber 86 for receiving the liquid reservoir 74. The first housing portion 78 is removable from the second housing portion 80 to enable replacement of the liquid reservoir 74.

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

[0051] The aerosol generator 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 an aerosol chamber 92 defined by the second housing portion 80.

[0052] The liquid storage unit 74 includes a container 94 and a liquid aerosol forming substrate 96 positioned within the container 94. When the storage unit connector 90 is engaged with the device connector 88, the liquid aerosol forming substrate 96 from the liquid storage unit 74 is supplied to the recess 62 of the atomizer assembly 50 through the storage unit connector 90, the device connector 88, and the liquid inlet 64 of the atomizer assembly 50.

[0053] When the first housing portion 78 is connected to the second housing portion 80, the controller 82 controls the supply of power from the power source 84 to the actuator 56 to discharge the 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 that are each in fluid communication with the aerosol chamber 92. During use, the user sucks on the mouthpiece 85 to draw air into the aerosol chamber 92 through the air inlet 98. The air flows through the aerosol chamber 92 where the droplets of the liquid aerosol forming substrate 96 discharged from the mesh 1 are entrained in the air stream 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 generating device 72 also includes an air flow sensor 102 positioned within the aerosol chamber 92. The air flow sensor 102 is arranged to provide a signal to the controller 82 indicating that the user is sucking on the mouthpiece 85. The controller 82 is arranged to supply power from the power source 84 to the actuator 56 of the atomizer assembly 50 only when the controller receives a signal from the air flow sensor 102 indicating that the user is sucking on the mouthpiece 85.

Claims

Claim 1: An atomizer assembly for an aerosol generating device for nicotine delivery, wherein the atomizer assembly comprises a mesh for an atomizer assembly comprising a first surface, a second surface, and a plurality of nozzles extending between the first surface and the second surface, wherein the second surface is at least partially coated with a hydrophobic coating, the nozzles define an inner surface, the inner surface is at least partially coated with a hydrophilic coating, each nozzle defines a first opening in the first surface and a second opening in the second surface, and the second opening has a diameter of 2.5 μm to 4 μm; an elastically deformable element; a recess positioned between the mesh and the elastically deformable element; a liquid inlet for providing a supply of atomized liquid to the recess; an actuator arranged to vibrate the elastically deformable element; and wherein the first opening is wider than the second opening, and each nozzle tapers from the first opening towards the second opening; the liquid has a viscosity of 15 mPas to 90 mPas; the atomizer assembly is operated at a resonant frequency; an atomizer assembly. Claim 2 The atomizer assembly according to claim 1, wherein the first surface is at least partially coated with a hydrophilic coating. Claim 3 The atomizer assembly according to claim 2, wherein the entire surface of the first surface, or the second surface, or both the first surface and the second surface is coated with the hydrophilic coating. Claim 4 The atomizer assembly according to any one of claims 1 to 3, wherein the hydrophobic coating comprises polyurethane (PU), or a superhydrophobic metal layer, or a combination of both. Claim 5 The atomizer assembly according to claim 4, wherein the superhydrophobic metal layer comprises a microporous metal functionalized with a carbon chain, or a metal mesh functionalized with a carbon chain. Claim 6 The atomizer assembly according to any one of claims 1 to 3, wherein the hydrophilic coating comprises at least one of the following: oxide; 3 polyamide; polyvinyl acetate; cellulose acetate; cotton. Claim 7 The atomizer assembly product according to any one of claims 1 to 3 or 6, wherein the hydrophilic coating contains at least one of the following: SiO 2 , Al 2 O 3 , TiO 2 , Ta 2 O 5 , HfO 2 . Claim 8 The atomizer assembly according to any one of claims 1 to 7, wherein the mesh is made of silicon. Claim 9 The atomizer assembly according to any one of claims 1 to 8, wherein the first surface of the mesh faces the recess, and the mesh is positioned such that the second surface of the mesh faces the outside of the atomizer assembly.

10. An aerosol generating device comprising the atomizer assembly according to any one of claims 1 to 9.

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