Converging aerosol generator

Abstract

An aerosol generator (100) for an aerosol generation apparatus (200) is provided, the aerosol generator (100) including a surface acoustic wave (SAW) atomizer (102) and a supply element (104). The SAW atomizer (102) includes: a substrate (106) including an active surface (110) defining an atomization region (116); and at least one transducer (108) positioned on the active surface (110) of the substrate (106) for generating surface acoustic waves on the active surface (110) of the substrate (106) for defining an acoustic wave front. The supply element (104) is arranged to supply a liquid aerosol forming matrix to the atomization region (116) such that the liquid aerosol forming matrix in the atomization region (116) defines the active surface (110) and the interface between the liquid aerosol forming matrix and the atmosphere. At least one transducer (108) and supply element (104) are configured such that the shape of the acoustic wavefront at the interface corresponds to the shape of at least a portion of the interface.

Description

Technical Field

[0001] This disclosure relates to an aerosol generator for an aerosol generation apparatus, the aerosol generator including a surface acoustic wave atomizer and a supply element configured to generate a shaped acoustic wavefront. This disclosure also relates to an aerosol generator for an aerosol generation apparatus, the aerosol generator including a first transducer and a second transducer driven by different driving signals. Background Technology

[0002] Aerosol generation systems in which the aerosol-forming matrix is ​​heated without combustion are known in the art. Typically, in such aerosol generation systems, aerosols are generated through energy transfer from the aerosol generator of the aerosol generation apparatus to the aerosol-forming matrix. For example, known aerosol generation apparatuses include heaters arranged to heat and evaporate the liquid aerosol-forming matrix.

[0003] An alternative to evaporating the liquid aerosol forming matrix using electrical heating is atomization using surface acoustic waves (SAWs). However, inhomogeneities in the piezoelectric materials used to generate SAWs can reduce or prevent the efficient transfer of energy from the SAWs to the liquid aerosol forming matrix. Summary of the Invention

[0004] The aim is to provide an aerosol generator for an aerosol generation device that facilitates the efficient atomization of liquid aerosols into a matrix using surface acoustic waves.

[0005] According to a first aspect of this disclosure, an aerosol generator for an aerosol generation apparatus is provided, the aerosol generator including a surface acoustic wave (SAW) atomizer and a supply element. The SAW atomizer includes: a substrate including an active surface defining an atomization region; and at least one transducer positioned on the active surface of the substrate for generating a surface acoustic wave on the active surface of the substrate to define an acoustic wavefront. The supply element is arranged to supply a liquid aerosol forming matrix to the atomization region such that the liquid aerosol forming matrix in the atomization region defines an interface between the active surface and the atmosphere. The at least one transducer and the supply element are configured such that the shape of the acoustic wavefront at the interface corresponds to the shape of at least a portion of the interface.

[0006] The term “surface acoustic wave” is used in this paper to include Rayleigh waves, Lamb waves, and Love waves.

[0007] Advantageously, the aerosol generator according to the first aspect of this disclosure provides an acoustic wavefront having a shape corresponding to the shape of at least a portion of the interface between the liquid aerosol forming matrix, the active surface of the surface acoustic wave atomizer substrate, and the atmosphere. Advantageously, matching the shape of the acoustic wavefront to the shape of at least a portion of the interface can improve or increase energy transfer from surface acoustic waves to the liquid aerosol forming matrix.

[0008] Preferably, at least one transducer includes an interdigitated transducer comprising an interlaced electrode array.

[0009] The spacing between the successive staggered electrodes of the transducer can vary with the direction across the active surface of the substrate. The inventors have recognized that anisotropy in the surface acoustic wave velocity across the active surface of the substrate can result in an acoustic wavefront having a shape different from that of the transducer. Advantageously, changing the spacing between the successive staggered electrodes of the transducer with the direction across the active surface of the substrate can generate an acoustic wavefront with a desired shape.

[0010] The staggered electrode array may have a symmetrical shape, which includes a first line of symmetry extending in a first direction and a second line of symmetry extending in a second direction. The first direction may be orthogonal to the second direction.

[0011] Each interleaved electrode may have an elliptical shape. Preferably, the interleaved electrodes are concentrically arranged on the active surface of the substrate. Preferably, the atomizing region is located at the center of the concentric interleaved electrode array.

[0012] Preferably, the interdigitated transducer defines a first direction extending along the main axis of the concentric interlaced electrodes and a second direction extending along the secondary axis of the concentric interlaced electrodes, wherein the spacing between the successive interlaced electrodes is larger in the first direction than in the second direction. Advantageously, the larger spacing between the successive interlaced electrodes in the first direction facilitates the generation of a substantially circular acoustic wavefront by the interdigitated transducer.

[0013] The substrate may comprise a crystalline material. Preferably, the active surface of the substrate is defined by a lattice plane of the crystalline material. Preferably, each of the first and second directions is aligned with a lattice vector of the lattice plane. Advantageously, aligning the first and second directions of the interdigitated transducer with the grid vector of the lattice plane further facilitates the generation of a substantially circular acoustic wavefront by the interdigitated transducer.

[0014] Preferably, the supply element includes an opening in the active surface of the substrate. Preferably, the opening is located within the atomization zone. Preferably, the opening has a substantially circular shape.

[0015] At least one transducer may include a first interdigital transducer and a second interdigital transducer. Preferably, the first interdigital transducer includes a first staggered electrode array. Preferably, the second interdigital transducer includes a second staggered electrode array. Preferably, the spacing between consecutive electrodes of the first staggered electrode array is different from the spacing between consecutive electrodes of the second staggered electrode array.

[0016] During use, a first interdigital transducer can generate a first acoustic wave, and a second interdigital transducer can generate a second acoustic wave, wherein the first and second acoustic waves define a combined acoustic wavefront. The inventors have recognized that anisotropy in the surface acoustic wave velocity across the active surface of the substrate can result in an acoustic wavefront having a shape different from that of the transducers disposed on the active surface of the substrate. Advantageously, providing a first interdigital transducer having a first electrode spacing and a second interdigital transducer having a second electrode spacing different from the first electrode spacing can generate a combined acoustic wavefront with a desired shape.

[0017] Preferably, the first interdigital transducer is configured to generate surface acoustic waves in a first direction along the active surface toward the atomization region. Preferably, the second interdigital transducer is configured to generate surface acoustic waves in a second direction along the active surface toward the atomization region. Preferably, the first direction is different from the second direction.

[0018] The first interdigital transducer and the second interdigital transducer can each be configured to generate planar surface acoustic waves.

[0019] Preferably, the first direction is orthogonal to the second direction.

[0020] The substrate may comprise a crystalline material. Preferably, the active surface of the substrate is defined by a lattice plane of the crystalline material. Preferably, each of the first and second directions is aligned with a lattice vector of the lattice plane. Advantageously, aligning the first and second directions, defined by the first and second interdigital transducers, with the lattice vector of the lattice plane facilitates the generation of a combined acoustic wavefront having a desired shape. The desired shape may be a symmetrical shape.

[0021] Preferably, the supply element includes an opening in the active surface of the substrate. Preferably, the opening is located within the atomization zone. The opening may have a substantially rectangular shape. The opening may have a substantially square shape.

[0022] Preferably, at least one transducer includes an interdigitated transducer comprising an interlaced electrode array.

[0023] Each interleaved electrode may have a circular shape. Preferably, the interleaved electrodes are concentrically arranged on the active surface of the substrate. Preferably, the atomizing region is located at the center of the concentric interleaved electrode array. Preferably, the supply element includes an opening in the active surface of the substrate. Preferably, the opening is located within the atomizing region. Preferably, the opening has an elliptical shape.

[0024] The inventors have recognized that anisotropy in the surface acoustic wave velocity across the active surface of a substrate can result in an acoustic wavefront having a shape different from that of the transducer. Specifically, for interdigitated transducers comprising a concentric array of circular staggered electrodes, the acoustic wavefront can have a non-circular shape. For example, the acoustic wavefront can have an elliptical shape. Advantageously, the elliptical shape of the opening can substantially correspond to the shape of the acoustic wavefront generated by the interdigitated transducer.

[0025] Preferably, the elliptical opening defines a first direction extending along the main axis of the opening and a second direction extending along the secondary axis of the opening.

[0026] The substrate may comprise a crystalline material. Preferably, the active surface of the substrate is defined by a lattice plane of the crystalline material. Preferably, each of the first and second directions is aligned with a lattice vector of the lattice plane. Advantageously, aligning the first and second directions of the elliptical opening with the lattice vector of the lattice plane facilitates matching the shape of the elliptical opening with the shape of the acoustic wavefront generated by the interdigital transducer.

[0027] The aerosol generator may include a controller. Preferably, the controller is configured to provide a drive signal to at least one transducer to generate surface acoustic waves on the active surface of the substrate.

[0028] The supply element may include a channel extending through the substrate between an inlet and an outlet. Preferably, the inlet is located on a blunt surface of the substrate. Preferably, the outlet is located on an active surface of the substrate. Preferably, the outlet is located within an atomization zone. In embodiments where the supply element includes an opening in the active surface of the substrate, preferably, the outlet is an opening.

[0029] The supply element may include a flow control element arranged to control the flow of the liquid aerosol forming matrix to the atomization zone. In embodiments where the supply element includes a channel, preferably, the flow control element is arranged to control the flow of the liquid aerosol forming matrix into the channel.

[0030] The flow control element may include at least one passive element. The at least one passive element may include at least one of a capillary and a capillary core.

[0031] The flow control element may include at least one active element. The at least one active element may include at least one of a micropump, syringe pump, piston pump, and electroosmotic pump.

[0032] In embodiments where the aerosol generator includes a controller, preferably, the controller is configured to provide a flow signal to a flow control element to enable the liquid aerosol forming matrix to flow into the atomization zone. Preferably, the controller is configured to provide a stop signal to a control element to disable the flow of the liquid aerosol forming matrix. Preferably, the controller is configured to provide a drive signal to at least one transducer only when the controller provides a flow signal to the flow control element.

[0033] A surface acoustic wave (SAW) atomizer may include at least one reflector. Preferably, the at least one reflector is positioned on an active surface of a substrate. Preferably, the at least one reflector is arranged to reflect surface acoustic waves generated by at least one transducer. Preferably, the at least one reflector is arranged to reflect surface acoustic waves generated by at least one transducer toward the atomization zone. Advantageously, a reflector arranged to reflect surface acoustic waves toward the atomization zone can increase or maximize the efficiency of the SAW atomizer.

[0034] At least one reflector may include one or more electrodes.

[0035] At least one reflector may include one or more portions of metal positioned on an active surface of a substrate. Each portion of the metal may have a linear shape. Each portion of the metal may have a curved shape. At least one reflector may include multiple portions of metal. Multiple metal portions may be arranged in a pattern on the active surface of the substrate. Preferably, each portion of the metal is substantially parallel to adjacent portions of the metal forming at least one reflector.

[0036] A portion of the substrate may form at least a portion of at least one reflector. The substrate may define at least one protrusion, wherein the at least one protrusion forms at least a portion of said at least one reflector. The substrate may define at least one recess, wherein the at least one recess forms at least a portion of at least one reflector.

[0037] A surface acoustic wave (SAW) atomizer may include at least one absorber. Preferably, the at least one absorber is positioned on an active surface of a substrate. Preferably, the at least one absorber is arranged to absorb surface acoustic waves generated by at least one transducer.

[0038] At least one absorber may comprise a material having at least one of low density, low sound velocity, and high viscosity. At least one absorber may comprise polydimethylsiloxane.

[0039] A portion of the substrate may form at least a portion of at least one absorber. The substrate may define at least one protrusion, wherein the at least one protrusion forms at least a portion of the at least one absorber. The substrate may define at least one recess, wherein the at least one recess forms at least a portion of the at least one absorber.

[0040] The substrate is formed from a substrate material. The substrate can be a piezoelectric material. The substrate material can include a single-crystal material. The substrate material can include a polycrystalline material. The substrate material can include at least one of quartz, ceramic, barium titanate (BaTiO3), and lithium niobate (LiNbO3). The ceramic can include lead zirconate titanate (PZT). The ceramic can include doped materials, such as Ni, Bi, La, Nd, or Nb ions. The substrate material can be polarized. The substrate material can be non-polarized. The substrate material can include both polarized and non-polarized materials.

[0041] The substrate may include a surface treatment. The surface treatment may be applied to an active surface of the substrate. The surface treatment may include a coating. The coating may include a hydrophobic material. The coating may include a hydrophilic material. The coating may include an oleophobic material. The coating may include an oleophilic material.

[0042] According to a second aspect of this disclosure, an aerosol generator for an aerosol generation apparatus is provided, the aerosol generator including a surface acoustic wave (SAW) atomizer and a supply element. The SAW atomizer includes: a substrate including an active surface defining an atomization region; and at least one transducer positioned on the active surface of the substrate for generating a surface acoustic wave on the active surface of the substrate to define an acoustic wavefront. The supply element is arranged to supply a liquid aerosol forming matrix to the atomization region such that the liquid aerosol forming matrix in the atomization region defines the active surface and an interface between the liquid aerosol forming matrix and the atmosphere. The at least one transducer includes: an interdigitated transducer including an array of staggered electrodes, wherein the spacing between the continuously staggered electrodes varies with the direction across the active surface.

[0043] The aerosol generator according to the second aspect of this disclosure may include any optional or preferred features described with respect to the first aspect of this disclosure.

[0044] According to a third aspect of this disclosure, an aerosol generator for an aerosol generation apparatus is provided, the aerosol generator including a surface acoustic wave (SAW) atomizer and a supply element. The SAW atomizer includes: a substrate including an active surface defining an atomization region; and at least one transducer positioned on the active surface of the substrate for generating a surface acoustic wave on the active surface of the substrate to define an acoustic wavefront. The supply element is arranged to supply a liquid aerosol forming matrix to the atomization region such that the liquid aerosol forming matrix in the atomization region defines the active surface and an interface between the liquid aerosol forming matrix and the atmosphere. The at least one transducer includes: a first interdigitated transducer including a first staggered electrode array, and a second interdigitated transducer including a second staggered electrode array. The spacing between consecutive electrodes of the first staggered electrode array is different from the spacing between consecutive electrodes of the second staggered electrode array.

[0045] The aerosol generator according to the third aspect of this disclosure may include any optional or preferred features described with respect to the first aspect of this disclosure.

[0046] According to a fourth aspect of this disclosure, an aerosol generator for an aerosol generation apparatus is provided, the aerosol generator comprising a surface acoustic wave (SAW) atomizer and a supply element. The SAW atomizer comprises: a substrate including an active surface defining an atomization region; and at least one transducer positioned on the active surface of the substrate for generating a surface acoustic wave on the active surface of the substrate to define an acoustic wavefront. The supply element is arranged to supply a liquid aerosol forming matrix to the atomization region such that the liquid aerosol forming matrix in the atomization region defines the active surface and an interface between the liquid aerosol forming matrix and the atmosphere. The at least one transducer comprises: an interdigitated transducer including an array of staggered electrodes, each of the staggered electrodes having a circular shape, and wherein the staggered electrodes are concentrically arranged on the active surface. The atomization region is located at the center of the concentric staggered electrode array. The supply element includes an opening in the active surface of the substrate and positioned within the atomization region, wherein the opening has an elliptical shape.

[0047] The aerosol generator according to the fourth aspect of this disclosure may include any optional or preferred features described with respect to the first aspect of this disclosure.

[0048] According to a fifth aspect of this disclosure, an aerosol generator for an aerosol generation apparatus is provided, the aerosol generator including a surface acoustic wave (SAW) atomizer, a supply element, and a controller. The SAW atomizer includes: a substrate including an active surface defining an atomization region, a first transducer, and a second transducer. The first transducer is positioned on the active surface of the substrate for generating surface acoustic waves in a first direction along the active surface toward the atomization region. The second transducer is positioned on the active surface of the substrate for generating surface acoustic waves in a second direction along the active surface toward the atomization region, wherein the first direction is different from the second direction. The supply element is arranged to supply a liquid aerosol forming matrix to the atomization region. The controller is configured to provide a first drive signal to the first transducer and a second drive signal to the second transducer, wherein the first drive signal is different from the second drive signal.

[0049] The inventors have recognized that anisotropy of the electromechanical coupling coefficient across the active surface of a substrate can result in surface acoustic waves traveling in different directions across the active surface having different amplitudes. Advantageously, the aerosol generator according to a fifth aspect of this disclosure includes a controller configured to drive a first transducer and a second transducer to generate surface acoustic waves in different first and second directions across the active surface of the substrate, wherein the first and second transducers are driven by different drive signals. Advantageously, the different drive signals can compensate for the anisotropy of the electromechanical coupling coefficient between the first and second directions. Advantageously, using different drive signals to compensate for the anisotropy of the electromechanical coupling coefficient can result in surface acoustic waves in the first and second directions having substantially the same amplitude. Advantageously, surface acoustic waves having the same amplitude in the first and second directions can improve or optimize the atomization of the liquid aerosol forming matrix in the atomization region.

[0050] Preferably, the power of the first driving signal is different from the power of the second driving signal.

[0051] The substrate may have a first electromechanical coupling coefficient in a first direction and a second electromechanical coupling coefficient in a second direction, wherein the first electromechanical coupling coefficient is greater than the second electromechanical coupling coefficient. Preferably, the power of the first driving signal is less than the power of the second driving signal. Preferably, the ratio of the first electromechanical coupling coefficient to the second electromechanical coupling coefficient is the same as the ratio of the power of the second driving signal to the power of the first driving signal.

[0052] The first direction can be orthogonal to the second direction.

[0053] The substrate may comprise a crystalline material. Preferably, the active surface of the substrate is defined by a lattice plane of the crystalline material. Preferably, each of the first and second directions is aligned with a lattice vector of the lattice plane. Advantageously, aligning the first and second directions with the lattice vector of the lattice plane can provide a substantially constant first electromechanical coupling coefficient in the first direction and a substantially constant second electromechanical coupling coefficient in the second direction.

[0054] Each of the first and second transducers may include an interdigitated transducer comprising a plurality of electrodes. Preferably, the plurality of electrodes are substantially parallel to each other. Preferably, the interdigitated transducer includes a first electrode array and a second electrode array interleaved with the first electrode array. Preferably, the first electrode array and the second electrode array are substantially parallel.

[0055] Each of the first and second transducers can be configured to generate surface acoustic waves with a substantially linear wavefront. In embodiments where the transducer is an interdigitated transducer comprising multiple electrodes, each electrode can be substantially linear.

[0056] Each of the first and second transducers can be configured to generate surface acoustic waves with a curved wavefront. In embodiments where the transducer is an interdigitated transducer comprising multiple electrodes, each electrode may be curved. The transducer can be configured to generate surface acoustic waves with a convex wavefront. Preferably, the transducer can be configured to generate surface acoustic waves with a concave wavefront. Advantageously, the concave wavefront can provide a focusing effect. In other words, the concave wavefront can focus the generated surface acoustic waves toward an atomization region smaller than that of the transducer. Advantageously, focusing the generated surface acoustic waves can increase the rate at which energy is delivered to the liquid aerosol forming matrix in the atomization region.

[0057] The supply element may include a channel extending through the substrate between an inlet and an outlet. Preferably, the inlet is located on a blunt surface of the substrate. Preferably, the outlet is located on an active surface of the substrate. Preferably, the outlet is located within an atomization zone.

[0058] The supply element may include a flow control element arranged to control the flow of the liquid aerosol forming matrix to the atomization zone. In embodiments where the supply element includes a channel, preferably, the flow control element is arranged to control the flow of the liquid aerosol forming matrix into the channel.

[0059] The flow control element may include at least one passive element. The at least one passive element may include at least one of a capillary and a capillary core.

[0060] The flow control element may include at least one active element. The at least one active element may include at least one of a micropump, syringe pump, piston pump, and electroosmotic pump.

[0061] Preferably, the controller is configured to provide a flow signal to the flow control element so that the liquid aerosol forming matrix can flow into the atomization zone. Preferably, the controller is configured to provide a stop signal to the control element to disable the flow of the liquid aerosol forming matrix. Preferably, the controller is configured to provide a first drive signal and a second drive signal to the first transducer and the second transducer only when the controller provides a flow signal to the flow control element.

[0062] A surface acoustic wave (SAW) atomizer may include at least one reflector. Preferably, the at least one reflector is positioned on an active surface of a substrate. Preferably, the at least one reflector is arranged to reflect surface acoustic waves generated by at least one of a first transducer and a second transducer. Preferably, the at least one reflector is arranged to reflect surface acoustic waves generated by at least one of the first transducer and the second transducer toward the atomization zone. Advantageously, a reflector arranged to reflect surface acoustic waves toward the atomization zone can increase or maximize the efficiency of the SAW atomizer.

[0063] At least one reflector may include one or more electrodes.

[0064] At least one reflector may include one or more portions of metal positioned on an active surface of a substrate. Each portion of the metal may have a linear shape. Each portion of the metal may have a curved shape. At least one reflector may include multiple portions of metal. Multiple metal portions may be arranged in a pattern on the active surface of the substrate. Preferably, each portion of the metal is substantially parallel to adjacent portions of the metal forming at least one reflector.

[0065] A portion of the substrate may form at least a portion of at least one reflector. The substrate may define at least one protrusion, wherein the at least one protrusion forms at least a portion of said at least one reflector. The substrate may define at least one recess, wherein the at least one recess forms at least a portion of at least one reflector.

[0066] A surface acoustic wave (SAW) atomizer may include at least one absorber. Preferably, at least one absorber is positioned on an active surface of a substrate. Preferably, at least one absorber is arranged to absorb surface acoustic waves generated by at least one of a first transducer and a second transducer.

[0067] At least one absorber may comprise a material having at least one of low density, low sound velocity, and high viscosity. At least one absorber may comprise polydimethylsiloxane.

[0068] A portion of the substrate may form at least a portion of at least one absorber. The substrate may define at least one protrusion, wherein the at least one protrusion forms at least a portion of the at least one absorber. The substrate may define at least one recess, wherein the at least one recess forms at least a portion of the at least one absorber.

[0069] The substrate is formed from a substrate material. The substrate can be a piezoelectric material. The substrate material can include a single-crystal material. The substrate material can include a polycrystalline material. The substrate material can include at least one of quartz, ceramic, barium titanate (BaTiO3), and lithium niobate (LiNbO3). The ceramic can include lead zirconate titanate (PZT). The ceramic can include doped materials, such as Ni, Bi, La, Nd, or Nb ions. The substrate material can be polarized. The substrate material can be non-polarized. The substrate material can include both polarized and non-polarized materials.

[0070] The substrate may include a surface treatment. The surface treatment may be applied to an active surface of the substrate. The surface treatment may include a coating. The coating may include a hydrophobic material. The coating may include a hydrophilic material. The coating may include an oleophobic material. The coating may include an oleophilic material.

[0071] According to a sixth aspect of this disclosure, an aerosol generator for an aerosol generation apparatus is provided, the aerosol generator including a surface acoustic wave (SAW) atomizer and a supply element. The SAW atomizer includes: a substrate including an active surface defining an atomization region; and a transducer positioned on the active surface of the substrate for generating surface acoustic waves on the active surface of the substrate. A portion of the active surface of the substrate overlying at least a portion of the transducer includes a surface treatment. The supply element is arranged to supply a liquid aerosol forming matrix to the atomization region.

[0072] The inventors have recognized that anisotropy in the electromechanical coupling coefficient across the active surface of a substrate can result in surface acoustic waves traveling in different directions across the active surface having different amplitudes. Advantageously, the surface treatment of the substrate of the aerosol generator according to the sixth aspect of this disclosure can at least partially compensate for the anisotropy in the electromechanical coupling coefficient. In other words, the surface treatment of the substrate can simulate or provide a substantially isotropic electromechanical coupling coefficient across at least a portion of the active surface of the substrate.

[0073] The substrate is formed from a substrate material. The substrate can be a piezoelectric material. The substrate material can include a single-crystal material. The substrate material can include a polycrystalline material. The substrate material can include at least one of quartz, ceramic, barium titanate (BaTiO3), and lithium niobate (LiNbO3). The ceramic can include lead zirconate titanate (PZT). The ceramic can include doped materials, such as Ni, Bi, La, Nd, or Nb ions. The substrate material can be polarized. The substrate material can be non-polarized. The substrate material can include both polarized and non-polarized materials.

[0074] Preferably, the surface treatment includes a proton exchange treatment. The substrate may include lithium niobate, wherein the proton exchange treatment includes replacing lithium ions with hydrogen ions in the portion of the active surface including the surface treatment.

[0075] Surface acoustic wave (SAW) atomizers may include a coating on at least a portion of the active surface of a substrate. The coating may include a hydrophobic material. The coating may include a hydrophilic material. The coating may include an oleophobic material. The coating may include an oleophilic material.

[0076] The aerosol generator may include a controller. Preferably, the controller is configured to provide a drive signal to the transducer to generate surface acoustic waves on the active surface of the substrate.

[0077] The transducer may include an interdigitated transducer comprising a plurality of electrodes. Preferably, the plurality of electrodes are substantially parallel to each other. Preferably, the interdigitated transducer includes a first electrode array and a second electrode array interleaved with the first electrode array. Preferably, the first electrode array and the second electrode array are substantially parallel.

[0078] The transducer can be configured to generate surface acoustic waves with a substantially linear wavefront. In embodiments where the transducer is an interdigitated transducer comprising multiple electrodes, each electrode can be substantially linear.

[0079] The transducer can be configured to generate surface acoustic waves with a curved wavefront. In embodiments where the transducer is an interdigitated transducer comprising multiple electrodes, each electrode may be curved. The transducer can be configured to generate surface acoustic waves with a convex wavefront. Preferably, the transducer can be configured to generate surface acoustic waves with a concave wavefront. Advantageously, the concave wavefront can provide a focusing effect. In other words, the concave wavefront can focus the generated surface acoustic waves toward a fogging region smaller than the transducer. Advantageously, focusing the generated surface acoustic waves can increase the rate at which energy is delivered to the liquid aerosol forming matrix in the fogging region.

[0080] The supply element may include a channel extending through the substrate between an inlet and an outlet. Preferably, the inlet is located on a blunt surface of the substrate. Preferably, the outlet is located on an active surface of the substrate. Preferably, the outlet is located within an atomization zone.

[0081] The supply element may include a flow control element arranged to control the flow of the liquid aerosol forming matrix to the atomization zone. In embodiments where the supply element includes a channel, preferably, the flow control element is arranged to control the flow of the liquid aerosol forming matrix into the channel.

[0082] The flow control element may include at least one passive element. The at least one passive element may include at least one of a capillary and a capillary core.

[0083] The flow control element may include at least one active element. The at least one active element may include at least one of a micropump, syringe pump, piston pump, and electroosmotic pump.

[0084] In embodiments where the aerosol generator includes a controller, preferably, the controller is configured to provide a flow signal to a flow control element to enable the liquid aerosol forming matrix to flow into the atomization zone. Preferably, the controller is configured to provide a stop signal to a control element to disable the flow of the liquid aerosol forming matrix. Preferably, the controller is configured to provide a drive signal to the transducer only when the controller provides a flow signal to the flow control element.

[0085] A surface acoustic wave (SAW) atomizer may include at least one reflector. Preferably, the at least one reflector is positioned on an active surface of a substrate. Preferably, the at least one reflector is arranged to reflect the surface acoustic waves generated by the transducer. Preferably, the at least one reflector is arranged to reflect the surface acoustic waves generated by the transducer toward the atomization zone. Advantageously, a reflector arranged to reflect surface acoustic waves toward the atomization zone can increase or maximize the efficiency of the SAW atomizer.

[0086] At least one reflector may include one or more electrodes.

[0087] At least one reflector may include one or more portions of metal positioned on an active surface of a substrate. Each portion of the metal may have a linear shape. Each portion of the metal may have a curved shape. At least one reflector may include multiple portions of metal. Multiple metal portions may be arranged in a pattern on the active surface of the substrate. Preferably, each portion of the metal is substantially parallel to adjacent portions of the metal forming at least one reflector.

[0088] A portion of the substrate may form at least a portion of at least one reflector. The substrate may define at least one protrusion, wherein the at least one protrusion forms at least a portion of said at least one reflector. The substrate may define at least one recess, wherein the at least one recess forms at least a portion of at least one reflector.

[0089] A surface acoustic wave (SAW) atomizer may include at least one absorber. Preferably, at least one absorber is positioned on an active surface of a substrate. Preferably, at least one absorber is arranged to absorb surface acoustic waves generated by a transducer.

[0090] At least one absorber may comprise a material having at least one of low density, low sound velocity, and high viscosity. At least one absorber may comprise polydimethylsiloxane.

[0091] A portion of the substrate may form at least a portion of at least one absorber. The substrate may define at least one protrusion, wherein the at least one protrusion forms at least a portion of the at least one absorber. The substrate may define at least one recess, wherein the at least one recess forms at least a portion of the at least one absorber.

[0092] According to a seventh aspect of this disclosure, an aerosol generating apparatus is provided. According to any embodiment described herein, the aerosol generating apparatus includes an aerosol generator according to any of the first to sixth aspects of this disclosure. The aerosol generating apparatus further includes a controller for controlling at least one transducer, a power supply, and a liquid storage section. The liquid storage section is used to receive a liquid aerosol forming matrix, wherein a supply element is arranged to supply the liquid aerosol forming matrix from the liquid storage section to an atomization zone.

[0093] The liquid storage section can be reusable. In other words, the liquid storage section can be refilled by the user to replenish the liquid aerosol forming matrix in the liquid storage section. The liquid storage section may include a refill orifice for inserting the liquid aerosol forming matrix into the liquid storage section. The liquid storage section may include a refill valve between the refill orifice and the liquid storage section. Advantageously, the refill valve may allow the liquid aerosol forming matrix to flow through the refill orifice into the liquid storage section. Advantageously, the refill valve may prevent the liquid aerosol forming matrix from flowing out of the liquid storage section through the refill orifice.

[0094] The liquid storage section may be replaceable. The liquid storage section may be removed from the aerosol generating apparatus. The aerosol generating apparatus may include a cylinder, wherein the cylinder is removable from the aerosol generating apparatus, and wherein the cylinder includes the liquid storage section.

[0095] The aerosol generating apparatus may include a liquid aerosol forming matrix contained within a liquid storage section.

[0096] The liquid aerosol forming matrix may include nicotine. Nicotine containing the liquid aerosol forming matrix may be a nicotine salt matrix. The liquid aerosol forming matrix may include plant-based materials. The liquid aerosol forming matrix may include tobacco. The liquid aerosol forming matrix may include homogenized tobacco material. The liquid aerosol forming matrix may include tobacco-free materials. The liquid aerosol forming matrix may include homogenized plant-based materials.

[0097] A liquid aerosol forming matrix may include at least one aerosol forming agent. An aerosol forming agent is any suitable known compound or mixture of compounds that contributes to the formation of a dense, stable aerosol during use. Suitable aerosol forming agents are well known in the art and include, but are not limited to: polyols, such as triethylene glycol, 1,3-butanediol, and glycerol; esters of polyols, such as mono-, di-, or triacetic acid esters of glycerol; and fatty acid esters of mono-, di-, or polycarboxylic acids, such as dimethyl dodecanoate and dimethyl tetradecanoate. The aerosol forming agent may be a polyol or a mixture thereof, such as triethylene glycol, 1,3-butanediol, and glycerol. A liquid aerosol forming matrix may include other additives and ingredients, such as fragrances.

[0098] Liquid aerosol matrix may include water.

[0099] The liquid aerosol forming matrix may include nicotine and at least one aerosol forming agent. The aerosol forming agent may include glycerol. The aerosol forming agent may include propylene glycol. The aerosol forming agent may include both glycerol and propylene glycol. The liquid aerosol forming matrix may have a nicotine concentration between about 0.1% and about 10%.

[0100] The controller may include circuitry connected to a power source and each transducer. The circuitry may include a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, an application-specific integrated circuit (ASIC), or other circuitry capable of providing control. The circuitry may include additional electronic components. The circuitry may be configured to regulate the power supply from the power source to each transducer. The controller may be configured to continuously supply power to each transducer after the aerosol generating device is activated. The controller may be configured to intermittently supply power to each transducer. The controller may be configured to sequentially pump power to each transducer.

[0101] Preferably, the controller and power supply are configured to provide an alternating voltage to each transducer. Preferably, the alternating voltage is a radio frequency alternating voltage. Preferably, the alternating voltage has a frequency of at least about 20 MHz. Preferably, the alternating voltage has a frequency between about 20 MHz and about 100 MHz, more preferably between about 20 MHz and about 80 MHz. Advantageously, alternating voltages within these ranges can provide at least one of a desired aerosol generation rate and a desired droplet size.

[0102] The power source can be any suitable type. It can be a DC power source. In some preferred embodiments, the power source is a battery, such as a rechargeable lithium-ion battery. The power source can also be another form of charge storage device, such as a capacitor. The power source may require recharging. The power source can have a capacity that allows sufficient energy to be stored for one or more uses of the device. For example, the power source can have sufficient capacity to allow continuous aerosol generation for approximately six minutes, corresponding to the typical time required to smoke a regular cigarette, or for a multiple of six minutes. In another instance, the power source can have sufficient capacity to allow for a predetermined number of uses of the device or intermittent use. In one embodiment, the power source is a DC power source having a DC supply voltage in the range of approximately 2.5 volts to approximately 4.5 volts and a DC supply current in the range of approximately 1 ampere to approximately 10 amperes (corresponding to a DC power source in the range of approximately 2.5 watts to approximately 45 watts).

[0103] The aerosol generating apparatus may advantageously include a DC / AC inverter, which may include a Class C, Class D, or Class E power amplifier. The DC / AC inverter may be arranged between the power supply and at least one transducer.

[0104] The aerosol generating device may be further included as a DC / DC converter between the power supply and the DC / AC inverter.

[0105] The aerosol generating device may include a housing. The housing may be elongated. The housing may include any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composites containing one or more of those materials, or thermoplastic materials suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. Preferably, the material is lightweight and non-brittle.

[0106] The device housing may define an air inlet. The air inlet may be configured to allow ambient air to enter the device housing. The air inlet may be in fluid communication with the atomizing zone of the aerosol generator. The device may include any suitable number of air inlets. The device may include multiple air inlets.

[0107] The device housing may include an air outlet. The air outlet may be configured to allow air to exit the device housing for delivery to a user. The air outlet may be in fluid communication with the atomizing zone of the aerosol generator. The aerosol generating device may include a mouthpiece. The mouthpiece may include an air outlet. The device may include any suitable number of air outlets. The device may include multiple air outlets. Attached Figure Description

[0108] The invention will be further described by way of example only with reference to the accompanying drawings, in which:

[0109] Figure 1 A top view of an aerosol generator according to a first embodiment of the present disclosure is shown;

[0110] Figure 2 The section cut along line 1-1 is shown. Figure 1 A cross-sectional view of the aerosol generator;

[0111] Figure 3 It shows including Figure 1 A cross-sectional view of the aerosol generating device of the aerosol generator;

[0112] Figure 4 A top view of an aerosol generator according to a second embodiment of the present disclosure is shown;

[0113] Figure 5 A top view of an aerosol generator according to a third embodiment of the present disclosure is shown;

[0114] Figure 6 A top view of an aerosol generator according to a fourth embodiment of the present disclosure is shown; and

[0115] Figure 7 A top view of an aerosol generator according to a fifth embodiment of the present disclosure is shown. Detailed Implementation

[0116] Figure 1 and 2 An aerosol generator 100 according to a first embodiment of the present disclosure is shown. The aerosol generator 100 includes a surface acoustic wave atomizer 102 and a supply element 104 for supplying a liquid aerosol forming matrix to the surface acoustic wave atomizer 102.

[0117] The surface acoustic wave (SAW) atomizer 102 includes a substrate 106 comprising a piezoelectric material sheet, and a transducer 108 disposed on an active surface 110 of the substrate 106. The transducer 108 is an interdigital transducer comprising an array of staggered electrodes 112. Each staggered electrode 112 has an elliptical shape, and the staggered electrodes 112 are concentrically arranged on the active surface 110 of the substrate 106. During use, the transducer 108 generates surface acoustic waves on the active surface 110 of the substrate 106. The concentric elliptical shape of the staggered electrode array 112 generates surface acoustic waves having an acoustic wavefront focused toward an atomization region 116 on the active surface 110 of the substrate 106.

[0118] The supply element 104 includes a channel 118 extending through the substrate 106 between an inlet 120 at the blunt surface 122 of the substrate 106 and an outlet 124 at the active surface 110 of the substrate 106. The outlet 124 is located within an atomization zone 116. The outlet 124 has a generally circular shape. The supply element 104 also includes a flow control element 130, which includes a micropump. During use, a liquid aerosol forming matrix is ​​supplied by the flow control element 130 through the channel 118 to the atomization zone 116, where it is atomized by surface acoustic waves generated by the transducer 108.

[0119] The aerosol generator 100 also includes a controller 132, which is arranged to control the transducer 108 and the flow control element 130. Figure 1 In the illustrated embodiment, the controller 132 is positioned on the substrate 106 of the surface acoustic wave atomizer 102; however, those skilled in the art will recognize that the controller 132 may be provided separately from the surface acoustic wave atomizer 102.

[0120] Controller 132 is configured to provide a drive signal to transducer 108 for generating surface acoustic waves on the active surface 110 of substrate 106. Controller 132 is also configured to provide flow and stop signals to flow control element 130 to start and stop the flow of the liquid aerosol forming matrix through channel 118 and into atomization zone 116. Controller 132 is configured to provide a drive signal to transducer 108 only when flow control element 130 supplies the liquid aerosol forming matrix to atomization zone 116.

[0121] Transducer 108 defines a first direction 140 extending along the principal axis of the elliptical staggered electrode 112. Transducer 108 also defines a second direction 142 extending along the secondary axis of the elliptical staggered electrode 112. The elliptical shape of the staggered electrode 112 causes the spacing between the consecutive staggered electrodes 112 to be greater in the first direction 140 than in the second direction 142.

[0122] The piezoelectric material forming the substrate 106 comprises a crystalline material, wherein the active surface 110 of the substrate 106 is defined by a lattice plane of the crystalline material. A transducer 108 is arranged on the active surface 110 of the substrate 106 such that each of the first and second directions defined by the transducer 108 is aligned with a lattice vector of the lattice plane. The combination of the elliptical shape of the staggered electrodes 112, the large spacing between the continuously staggered electrodes 112 in the first direction 140, and the alignment of the first and second directions 140 and the lattice vectors of the lattice planes defining the active surface 110 of the substrate 106 compensates for the anisotropy of the surface acoustic wave velocity across the active surface 110. Therefore, during use, the transducer 108 generates surface acoustic waves having a substantially circular wavefront that converges at the substantially circular outlet 124 of the supply element 104 and the atomization zone 116.

[0123] Figure 3 It shows including Figure 1 and 2 A cross-sectional view of the aerosol generating apparatus 200 of the aerosol generator 100. The aerosol generating apparatus 200 also includes a liquid storage section 202 containing a liquid aerosol forming matrix 204. A flow control element 130 of the aerosol generator 100 is arranged to supply the liquid aerosol forming matrix 204 from the liquid storage section 202 to the inlet 120 of the aerosol generator 100.

[0124] The aerosol generating apparatus 200 also includes a power source 208, which includes a rechargeable battery for supplying power to the controller 132, the transducer 108, and the flow control element 130.

[0125] The aerosol generating device 200 also includes a housing 212 in which the aerosol generator 100, a liquid storage section 202, and a power supply 208 are housed. The housing 212 defines an air inlet 214, a mouthpiece 216, and an air outlet 218. During use, the user inhales through the mouthpiece 216 to draw air from the air inlet 214 to the air outlet 218 through the housing 212. The aerosol generated by the aerosol generator 100 is entrained in the airflow passing through the housing 212 for delivery to the user.

[0126] Figure 4An aerosol generator 300 according to a second embodiment of the present invention is shown. The aerosol generator 300 includes a surface acoustic wave atomizer 302 and a supply element 304 for supplying a liquid aerosol forming matrix to the surface acoustic wave atomizer 302.

[0127] The surface acoustic wave atomizer 302 includes: a substrate 306 including a piezoelectric material sheet, a first transducer 308 disposed on an active surface 310 of the substrate 306, and a second transducer 309 disposed on the active surface 310 of the substrate 306.

[0128] The first transducer 308 is an interdigital transducer including an array of first interlaced electrodes 312. Each interlaced electrode 312 has a linear shape and is arranged parallel to each other on the active surface 310 of the substrate 306. During use, the first transducer 308 generates substantially planar surface acoustic waves on the active surface 310 of the substrate 306 and directs the surface acoustic waves toward atomization regions 316 on the active surface 310 of the substrate 306.

[0129] The second transducer 309 is an interdigital transducer including a second array of interlaced electrodes 313. Each interlaced electrode 313 has a linear shape and is arranged parallel to each other on the active surface 310 of the substrate 306. During use, the second transducer 309 generates substantially planar surface acoustic waves on the active surface 310 of the substrate 306 and directs the surface acoustic waves toward the atomization region 316 on the active surface 310 of the substrate 306.

[0130] Supply component 304 is similar to the reference. Figure 1 The described supply element 104. Supply element 304 includes a channel 318 extending through substrate 306 between an inlet at a blunt surface of substrate 306 and an outlet 324 at an active surface 310 of substrate 306. Outlet 324 is positioned within atomization zone 316. Outlet 324 has a substantially square shape. Supply element 304 also includes a flow control element comprising a micropump. During use, a liquid aerosol forming matrix is ​​supplied by the flow control element through channel 318 to atomization zone 316, where it is atomized by surface acoustic waves generated by a first transducer 308 and a second transducer 309.

[0131] The aerosol generator 300 also includes a controller 332, which is arranged to control the first transducer 308, the second transducer 309, and flow control elements. Figure 4 In the illustrated embodiment, the controller 332 is positioned on the substrate 306 of the surface acoustic wave atomizer 302; however, those skilled in the art will recognize that the controller 332 may be provided separately from the surface acoustic wave atomizer 302.

[0132] The controller 332 is configured to provide a first drive signal and a second drive signal to the first transducer 308 and the second transducer 309 for generating surface acoustic waves on the active surface 310 of the substrate 306. The controller 332 is also configured to provide a flow signal and a stop signal to a flow control element to start and stop the flow of the liquid aerosol forming matrix through the channel 318 and into the atomization zone 316. The controller 332 is configured to provide the first drive signal and the second drive signal to the first transducer 308 and the second transducer 309 only when the flow control element supplies the liquid aerosol forming matrix to the atomization zone 316.

[0133] A first transducer 308 is disposed on the active surface 310 of the substrate 306 to generate surface acoustic waves in a first direction 340. A second transducer 309 is disposed on the active surface 310 of the substrate 306 to generate surface acoustic waves in a second direction 342. The spacing between the consecutively interleaved electrodes 312 of the first transducer 308 in the first direction 340 is greater than the spacing between the consecutively interleaved electrodes 313 of the second transducer 309 in the second direction 342.

[0134] The piezoelectric material forming the substrate 306 includes a crystalline material, wherein the active surface 310 of the substrate 306 is defined by a lattice plane of the crystalline material. A first transducer 308 and a second transducer 309 are arranged on the active surface 310 of the substrate 306 such that each of the first and second directions defined by the first transducer 308 and the second transducer 309 is aligned with the lattice vector of the lattice plane. The large spacing between the continuously interlaced electrodes 312 on the first direction 340 and the combination of the alignment of the first direction 340 and the second direction 342 with the lattice vector of the lattice plane defining the active surface 310 of the substrate 306 compensates for the anisotropy of the surface acoustic wave velocity across the active surface 310. Therefore, during use, the surface acoustic wave generated by the first transducer 308 can arrive at the atomization region 316 simultaneously with the surface acoustic wave generated by the second transducer 309.

[0135] Figure 5 An aerosol generator 400 according to a third embodiment of the present invention is shown. The aerosol generator 400 includes a surface acoustic wave atomizer 402 and a supply element 404 for supplying a liquid aerosol forming matrix to the surface acoustic wave atomizer 402.

[0136] The surface acoustic wave (SAW) atomizer 402 includes a substrate 406 comprising a piezoelectric material sheet, and a transducer 408 disposed on an active surface 410 of the substrate 406. The transducer 408 is an interdigitated transducer comprising an array of staggered electrodes 412. Each staggered electrode 412 has a generally circular shape, and the staggered electrodes 412 are concentrically arranged on the active surface 410 of the substrate 406. During use, the transducer 408 generates surface acoustic waves on the active surface 410 of the substrate 406. The concentric circular shape of the staggered electrode array generates surface acoustic waves having an acoustic wavefront focused toward an atomization region 416 on the active surface 410 of the substrate 406.

[0137] Supply component 404 is similar to reference Figure 1 The described supply element 104. Supply element 404 includes a channel 418 extending through substrate 406 between an inlet at a blunt surface of substrate 406 and an outlet 424 at an active surface 410 of substrate 406. Outlet 424 is positioned within atomization zone 416. Outlet 424 has an elliptical shape. Supply element 404 also includes a flow control element comprising a micropump. During use, a liquid aerosol forming matrix is ​​supplied by the flow control element through channel 418 to atomization zone 416, where it is atomized by surface acoustic waves generated by transducer 408.

[0138] The aerosol generator 400 also includes a controller 432, which is arranged to control the transducer 408 and flow control elements. Figure 4 In the illustrated embodiment, the controller 432 is positioned on the substrate 406 of the surface acoustic wave atomizer 402; however, those skilled in the art will recognize that the controller 432 may be provided separately from the surface acoustic wave atomizer 402.

[0139] Controller 432 is configured to provide a drive signal to transducer 408 for generating surface acoustic waves on the active surface 410 of substrate 406. Controller 432 is also configured to provide flow and stop signals to flow control elements to start and stop the flow of the liquid aerosol forming matrix through channel 418 and into atomization zone 416. Controller 432 is configured to provide a drive signal to transducer 408 only when the flow control elements are supplying the liquid aerosol forming matrix to atomization zone 416.

[0140] The elliptical outlet 424 defines a first direction 440 extending along the secondary axis of the elliptical outlet 424. The elliptical outlet 424 also defines a second direction 442 extending along the primary axis of the elliptical outlet 424.

[0141] The piezoelectric material forming the substrate 406 comprises a crystalline material, wherein the active surface 410 of the substrate 406 is defined by a lattice plane of the crystalline material. An elliptical outlet 424 is arranged on the active surface 410 of the substrate 406 such that each of the first and second directions defined by the elliptical outlet 424 is aligned with a lattice vector of the lattice plane. Although the staggered electrodes 412 of the transducer 408 each have a substantially circular shape, the anisotropy of the wave velocity of the surface acoustic wave across the active surface 410 of the substrate results in the surface acoustic wave generated by the transducer 408 having an elliptical wavefront. The combination of the elliptical shape of the outlet 424 and the alignment of the first direction 440 and the second direction 442 with the lattice vector of the lattice plane defining the active surface 410 of the substrate compensates for the anisotropy of the wave velocity of the surface acoustic wave across the active surface 410. Therefore, during use, the transducer 408 generates surface acoustic waves with an elliptical wavefront that converges at the atomization zone 416 and the elliptical outlet 424 of the supply element 404.

[0142] Figure 6 An aerosol generator 500 according to a fourth embodiment of the present invention is shown. The aerosol generator 500 includes a surface acoustic wave atomizer 502 and a supply element 504 for supplying a liquid aerosol forming matrix to the surface acoustic wave atomizer 502.

[0143] The surface acoustic wave atomizer 502 includes: a substrate 506 including a piezoelectric material sheet, and a first transducer 508, a second transducer 509, a third transducer 511 and a fourth transducer 517 respectively disposed on the active surface 510 of the substrate 506.

[0144] Each of the first transducer 508, the second transducer 509, the third transducer 511, and the fourth transducer 517 is an interdigitated transducer comprising an array of interlaced electrodes 512. Each interlaced electrode 512 has a linear shape and is arranged parallel to each other on the active surface 510 of the substrate 506. During use, each of the first transducer 508, the second transducer 509, the third transducer 511, and the fourth transducer 517 generates a substantially planar surface acoustic wave on the active surface 510 of the substrate 506 and directs the surface acoustic wave toward an atomization region 516 on the active surface 510 of the substrate 506.

[0145] Supply component 504 is similar to the reference. Figure 1The described supply element 104. Supply element 504 includes a channel 518 extending through substrate 506 between an inlet at a blunt surface of substrate 506 and an outlet 524 at an active surface 510 of substrate 506. Outlet 524 is positioned within atomization zone 516. Outlet 524 has a substantially square shape. Supply element 504 also includes a flow control element comprising a micropump. During use, a liquid aerosol forming matrix is ​​supplied by the flow control element through channel 518 to atomization zone 516, where it is atomized by surface acoustic waves generated by a first transducer 508 and a second transducer 509.

[0146] The aerosol generator 500 also includes a controller 532, which is arranged to control the first transducer 508, the second transducer 509, the third transducer 511, and the fourth transducer 517, and flow control elements. Figure 6 In the illustrated embodiment, the controller 532 is positioned on the substrate 506 of the surface acoustic wave atomizer 502; however, those skilled in the art will recognize that the controller 532 may be provided separately from the surface acoustic wave atomizer 502.

[0147] The controller 532 is configured to provide a first drive signal 550 to the first transducer 508 for generating surface acoustic waves along a first direction 540 on the active surface 510 of the substrate 506.

[0148] The controller 532 is configured to provide a second drive signal 552 to the second transducer 509 for generating surface acoustic waves along a second direction 542 on the active surface 510 of the substrate 506.

[0149] The controller 532 is configured to provide a third drive signal 554 to the third transducer 511 for generating surface acoustic waves along a third direction 544 on the active surface 510 of the substrate 506.

[0150] The controller 532 is configured to provide a fourth drive signal 556 to the fourth transducer 517 for generating surface acoustic waves along a fourth direction 546 on the active surface 510 of the substrate 506.

[0151] The controller 532 is also configured to provide flow and stop signals to the flow control element to start and stop the flow of the liquid aerosol forming matrix through the channel 518 and into the atomization zone 516. The controller 532 is configured to provide a first drive signal 550, a second drive signal 552, a third drive signal 554, and a fourth drive signal 556 to the first transducer 508, the second transducer 509, the third transducer 511, and the fourth transducer 517 only when the flow control element supplies the liquid aerosol forming matrix to the atomization zone 516.

[0152] The controller 532 is configured such that the power of each of the first drive signal 550, the second drive signal 552, the third drive signal 554, and the fourth drive signal 556 is different from each other.

[0153] The piezoelectric material forming the substrate 506 comprises a crystalline material, wherein the active surface 510 of the substrate 506 is defined by a lattice plane of the crystalline material. A first transducer 508, a second transducer 509, a third transducer 511, and a fourth transducer 517 are arranged on the active surface 510 of the substrate 506 such that each of the first direction 540, the second direction 542, the third direction 544, and the fourth direction 546 is aligned with a lattice vector of the lattice plane. The different powers of the first drive signal 550, the second drive signal 552, the third drive signal 554, and the fourth drive signal 556, and the combination of the alignment of the first direction 540 and the second direction 542 with the lattice vectors defining the lattice plane of the active surface 510 of the substrate 506, compensate for the anisotropy of the electromechanical coupling coefficient across the active surface 510. Therefore, during use, the surface acoustic waves generated by each of the first transducer 508, the second transducer 509, the third transducer 511, and the fourth transducer 517 have the same amplitude.

[0154] Figure 7 An aerosol generator 600 according to a fifth embodiment of the present invention is shown. The aerosol generator 600 includes a surface acoustic wave atomizer 602 and a supply element 504.

[0155] Supply element 504 of aerosol generator 600 and reference Figure 6 The supply element 504 described is the same, and similar reference numerals are used to identify similar parts.

[0156] The surface acoustic wave atomizer 602 is similar to the reference. Figure 6 The surface acoustic wave (SAW) atomizer 502 is described, and similar reference numerals are used to identify similar components. SAW atomizer 602 differs from SAW atomizer 502 by adding a surface treatment 660 covering a portion of the active surface 510 of the substrate 506 over which the first transducer 508, second transducer 509, third transducer 511, and fourth transducer 517 are applied. Surface treatment 660 includes a proton exchange process and provides a substantially isotropic electromechanical coupling coefficient to the active surface 510 of the substrate 506 in the region to which surface treatment 660 is applied. Therefore, controller 632 is configured to provide a common drive signal 650 to each of the first transducer 508, second transducer 509, third transducer 511, and fourth transducer 517.

Claims

1. An aerosol generator for an aerosol generating apparatus, the aerosol generator comprising: Surface acoustic wave atomizer, the surface acoustic wave atomizer comprising: A substrate, the substrate including an active surface defining an atomization region; and At least one transducer, the at least one transducer being positioned on an active surface of the substrate for generating a surface acoustic wave defining an acoustic wavefront on the active surface of the substrate; and A supply element is arranged to supply a liquid aerosol forming matrix to the atomization zone, such that the liquid aerosol forming matrix in the atomization zone defines the active surface and the interface between the liquid aerosol forming matrix and the atmosphere; The at least one transducer and the supply element are configured such that the shape of the acoustic wavefront at the interface corresponds to the shape of at least a portion of the interface; The at least one transducer includes: an interdigital transducer comprising an interlaced electrode array; The spacing between the continuously interleaved electrodes varies with the direction across the active surface; Each of the interleaved electrodes described herein has an elliptical shape; and The staggered electrodes are concentrically arranged on the active surface.

2. The aerosol generator according to claim 1, wherein the atomizing zone is located at the center of the concentric interleaved electrode array.

3. The aerosol generator of claim 1, wherein the interdigitated transducer defines a first direction extending along the main axis of the concentric interdigitated electrodes and a second direction extending along the secondary axis of the concentric interdigitated electrodes, and wherein the spacing between the consecutive interdigitated electrodes is greater in the first direction than in the second direction.

4. The aerosol generator according to claim 1, wherein the staggered electrode array has a symmetrical shape, the symmetrical shape including a first symmetrical line extending in a first direction and a second symmetrical line extending in a second direction, wherein the first direction is orthogonal to the second direction.

5. An aerosol generator for an aerosol generating apparatus, the aerosol generator comprising: Surface acoustic wave atomizer, the surface acoustic wave atomizer comprising: A substrate, the substrate including an active surface defining an atomization region; and At least one transducer, the at least one transducer being positioned on an active surface of the substrate for generating a surface acoustic wave defining an acoustic wavefront on the active surface of the substrate; and A supply element is arranged to supply a liquid aerosol forming matrix to the atomization zone, such that the liquid aerosol forming matrix in the atomization zone defines the active surface and the interface between the liquid aerosol forming matrix and the atmosphere; The at least one transducer and the supply element are configured such that the shape of the acoustic wavefront at the interface corresponds to the shape of at least a portion of the interface; The at least one transducer comprises: a first interdigital transducer including a first interlaced electrode array, and a second interdigital transducer including a second interlaced electrode array; and The spacing between the consecutive electrodes of the first staggered electrode array is different from the spacing between the consecutive electrodes of the second staggered electrode array.

6. The aerosol generator of claim 5, wherein the first interdigital transducer is configured to generate surface acoustic waves in a first direction along the active surface toward the atomization region, wherein the second interdigital transducer is configured to generate surface acoustic waves in a second direction along the active surface toward the atomization region, and wherein the first direction is different from the second direction.

7. The aerosol generator of claim 6, wherein each of the first interdigital transducer and the second interdigital transducer is configured to generate planar surface acoustic waves.

8. The aerosol generator according to claim 6, wherein the first direction is orthogonal to the second direction.

9. An aerosol generator for an aerosol generating apparatus, the aerosol generator comprising: Surface acoustic wave atomizer, the surface acoustic wave atomizer comprising: A substrate, the substrate including an active surface defining an atomization region; A first transducer, positioned on the active surface of the substrate, is used to generate surface acoustic waves in a first direction along the active surface toward the atomization region; and A second transducer is positioned on the active surface of the substrate to generate surface acoustic waves in a second direction along the active surface toward the atomization region, wherein the first direction is different from the second direction. Supply elements, the supply elements being arranged to supply a liquid aerosol forming matrix to the atomization zone; and A controller configured to provide a first drive signal to the first transducer and a second drive signal to the second transducer, wherein the first drive signal is different from the second drive signal.

10. The aerosol generator according to claim 9, wherein the power of the first driving signal is different from the power of the second driving signal.

11. The aerosol generator of claim 10, wherein the substrate has a first electromechanical coupling coefficient in the first direction and a second electromechanical coupling coefficient in the second direction, wherein the first electromechanical coupling coefficient is greater than the second electromechanical coupling coefficient, and wherein the power of the first driving signal is less than the power of the second driving signal.

12. The aerosol generator according to claim 11, wherein the ratio of the first electromechanical coupling coefficient to the second electromechanical coupling coefficient is the same as the ratio of the power of the second drive signal to the power of the first drive signal.

13. The aerosol generator of claim 9, wherein the first direction is orthogonal to the second direction.

14. The aerosol generator according to claim 3 or claim 4, or any one of claims 6 to 13, wherein the substrate comprises a crystalline material, wherein the active surface is defined by a lattice plane of the crystalline material, and wherein each of the first direction and the second direction is aligned with a lattice vector of the lattice plane.

15. An aerosol generator for an aerosol generating apparatus, the aerosol generator comprising: Surface acoustic wave atomizer, the surface acoustic wave atomizer comprising: A substrate, the substrate including an active surface defining an atomization region; and A transducer positioned on the active surface of the substrate for generating surface acoustic waves on the active surface of the substrate. A portion of the active surface of the substrate covering at least a portion of the transducer includes a surface treatment, wherein the surface treatment includes a proton exchange treatment and provides a substantially isotropic electromechanical coupling coefficient to the active surface of the substrate in the region to which the surface treatment is applied; and A supply element, the supply element being arranged to supply a liquid aerosol forming matrix to the atomization zone.

16. The aerosol generator of claim 15, wherein the substrate comprises lithium niobate, and wherein the proton exchange treatment comprises replacing lithium ions with hydrogen ions in a portion of the active surface including the surface treatment.

17. An aerosol generating apparatus, comprising: The aerosol generator according to any one of claims 1 to 16; A controller for controlling the at least one transducer; power supply; as well as A liquid storage section for receiving a liquid aerosol forming matrix, wherein the supply element is arranged to supply the liquid aerosol forming matrix from the liquid storage section to the atomization zone.

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