US20140261488A1

US20140261488A1 - Electronic smoking article

Info

Publication number: US20140261488A1
Application number: US14/199,365
Authority: US
Inventors: Christopher S. Tucker
Original assignee: Altria Client Services LLC
Current assignee: Altria Client Services LLC
Priority date: 2013-03-15
Filing date: 2014-03-06
Publication date: 2014-09-18
Also published as: WO2014150131A1; RU2015144179A; AR095999A1; CA2904856A1; KR20160008510A; EP2967141A1; CN105324045A; MA38386A1

Abstract

An electronic smoking article includes a first capillary aerosol generator and a second capillary aerosol generator. The first capillary aerosol generator produces an aerosol having a first particle size distribution and the second capillary aerosol generator produces an aerosol having a second particle size distribution.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119(e) to U.S. provisional Application No. 61/798,010, filed on Mar. 15, 2013, the entire content of which is incorporated herein by reference thereto.

WORKING ENVIRONMENT

Many of the embodiments disclosed herein include electronic smoking articles which include heated capillary aerosol generators. The heated capillary volatilizes a liquid such as by way of the teachings set forth in U.S. Pat. No. 5,743,251, which is incorporated herein in its entirety by reference thereto.

SUMMARY OF SELECTED FEATURES

An electronic smoking article comprising a first capillary aerosol generator which produces a first aerosol of a first liquid material including flavor material and a second capillary aerosol generator which produces a second aerosol of a second liquid material, the second liquid material including nicotine. The first aerosol has a first particle size distribution and the second aerosol has a second particle size distribution.
A method of forming an aerosol containing two particle size distributions comprises supplying a first liquid containing flavor material to a first capillary tube, supplying a second liquid containing nicotine to a second capillary tube, simultaneously heating the first capillary tube and the second capillary tube to a temperature sufficient to volatilize the first liquid and the second liquid to form a first vapor and a second vapor, mixing the first vapor with air to produce a first aerosol, mixing the second vapor with air to produce a second aerosol, and combining the first and second aerosols in a mixing chamber. The heating of the first capillary tube and the heating of the second capillary tube can occur within a puff cycle at different times within the puff cycle. Moreover, the heating of the first capillary tube and the heating of the second capillary tube occur within a puff cycle and achieve different temperatures within the puff cycle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an electronic smoking article.

FIG. 2 is a cross-sectional view of the electronic smoking article of FIG. 1.

FIG. 3 is an illustration of a capillary tube having a constriction adjacent an outlet of the capillary tube.

FIG. 4 is a cross-sectional view of a second embodiment of an electronic smoking article including two capillary aerosol generators.

DETAILED DESCRIPTION

An electronic smoking article, such as an electronic cigarette or an electronic cigar, is described herein which produces an aerosol having two different particle size distributions. A first particle size distribution is formed using a first capillary aerosol generator having a first liquid supply reservoir that contains liquid material. A second particle size distribution is formed using a second capillary aerosol generator having a second liquid supply reservoir that contains liquid material. The first liquid material can include flavor material and the second liquid material can include nicotine. The first liquid supply reservoir and the second liquid supply reservoir can contain liquids having different viscosities.
Advantageously, by providing an aerosol with two different particle size distributions, the aerosol can be tailored to provide desired flavor and/or therapeutic compositions. For example, the flavor compounds can have a larger median particle size so as to be deposited in the mouth and throat, while functional compounds, such as nicotine or therapeutic compounds can be provided in smaller particle sizes so as to deliver the particles deeper into the lower respiratory tract.
As shown in FIG. 1, an electronic smoking article 60 comprises a replaceable cartridge (or first section) 70 and a reusable fixture (or second section) 72, which are coupled together at a threaded joint 74 or by other convenience such as a snug-fit, snap-fit, detent, clamp and/or clasp.
The first section 70 can house a mouth-end insert 20, two capillary tubes 18 a, 18 b, two heaters 19 a, 19 b to heat at least a portion of each capillary tube 18 a, 18 b (which may comprise a heatable portion 19 a, 19 b of the capillary tube 18 a, 18 b itself) and two liquid supply reservoirs 14 a, 14 b. The second section 72 can house a power supply 12, control circuitry 11 and a puff sensor 16. A threaded portion of the section 72 can be connected to a battery charger when not connected to the first section 70 for use so as to charge the battery.
Preferably, the first section 70 and the second section 72 include an outer cylindrical housing 22 extending in a longitudinal direction along the length of the electronic smoking article 60. Preferably, the outer tube 6 is formed of a metal and is part of the electrical circuit. In other embodiments, the outer tube 6 can formed of any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics or composite materials containing one or more of those materials, or thermoplastics that are suitable for food or pharmaceutical applications, for example polypropylene, polyetheretherketone (PEEK), ceramic, and polyethylene. Preferably, the material is light and non-brittle.
In one embodiment, the first section 70 is disposable and the second section 72 is reusable. In another embodiment, both the first section 70 and the second section 72 are disposable. The sections 70, 72 can be attached by a threaded connection.
In the preferred embodiment, each liquid supply reservoir 14 a, 14 b is a tubular, elongate body that holds a predetermined quantity of liquid material. Preferably, each liquid supply reservoir 14 a, 14 b is pressurized such that the liquid material therein is under constant pressure. As shown in FIG. 2, each liquid supply reservoir 14 a, 14 b can include a pressurization arrangement 50 a, 50 b, such as an internal or external spring and plate arrangement which constantly applies pressure to each liquid supply reservoir 14 a, 14 b. For example, each liquid supply reservoir 14 a, 14 b can be compressible and positioned between two plates that are connected by springs. Alternatively, each liquid supply reservoir 14 a, 14 b could be compressible and positioned between the outer housing and a plate and the plate and outer housing could be connected by a spring so that the plate applies pressure to each liquid supply reservoir 14 a, 14 b.
Preferably, each liquid supply reservoir 14 a, 14 b has an outlet 16 a, 16 b which is in fluid communication with a capillary tube 18 a, 18 b. A valve 40 a, 40 b connects each outlet 16 a, 16 b to the respective capillary tube 18 a, 18 b so as to prevent flow of liquid material when the electronic smoking article 60 is not in use. When each valve 40 a, 40 b is opened, each liquid supply reservoir 14 a, 14 b can deliver a volume of liquid material to one of the capillary tubes 18 a, 18 b. During delivery of liquid to the capillary tubes 18 a, 18 b, the power supply 12 is activated and each capillary tube 18 a, 18 b is heated to form a heated section wherein the liquid material is volatilized. Upon discharge from the heated capillary tubes 18 a, 18 b, two streams of volatilized material mix with air that enters the electronic smoking article 60 via air inlets 44, and form two aerosols which are combined in a mixing chamber 46.
Preferably, each liquid supply reservoir 14 a, 14 b extends longitudinally within the outer cylindrical housing 22 of the first section 70. Moreover, each liquid supply reservoir 14 a, 14 b can comprise a different liquid material which is volatilized when heated and forms an aerosol. Each aerosol can have the same or different particle size distributions. For example, the liquid supply reservoir 14 a can include flavor material, while the liquid supply reservoir 14 b can include a tobacco derived ingredient, such as nicotine.
In the preferred embodiment, each capillary tube 18 a, 18 b includes an inlet end 62 a, 62 b in fluid communication with the outlet 16 a, 16 b of the liquid supply reservoir 14 a, 14 b, and an outlet end 63 a, 63 b operable to expel volatilized liquid material from each capillary tube 18 a, 18 b. In some embodiments, one or both capillary tube 18 a, 18 b can include a constriction 101 a (shown in FIG. 3) at an outlet end 63 a, 63 b of the capillary tube 18 a, 18 b. While not wishing to be bound by theory, it is believed that the addition of a constriction at the outlet of the capillary tube, which reduces the cross-sectional area of the outlet end, can create sufficiently high shear forces to break up coarse droplets, which can increase the conversion of the liquid material to small particles.
Preferably, each capillary tube 18 a, 18 b has a different internal diameter so as to aid in promoting formation of an aerosol having a particular particle size distribution. For example, each of the capillary tubes 18 a, 18 b can have an internal diameter of 0.01 to 10 mm, preferably 0.05 to 1 mm, and more preferably 0.05 to 0.4 mm. For example, the capillary tube 18 a can have an internal diameter of about 0.05 mm and the capillary tube 18 b can have an internal diameter of about 0.4 mm. Capillary tubes of smaller diameter provide more efficient heat transfer to the fluid because, with the shorter the distance to the center of the fluid, less energy and time is required to vaporize the liquid.
Also preferably, each capillary tube 18 a, 18 b may have a length of about 5 mm to about 72 mm, more preferably about 10 mm to about 60 mm or about 20 mm to about 50 mm. For example, each capillary tube 18 a, 18 b can be about 50 mm in length and arranged such that a downstream, about 40 mm long portion of the capillary tube 18 a, 18 b forms a coiled heated section and an upstream, about 10 mm long portion of the capillary tube 18 a, 18 b remains relatively unheated when the heater 19 a, 19 b is activated.
In one embodiment, each capillary tube 18 a, 18 b is substantially straight. In other embodiments, one or both capillary tubes 18 a, 18 b are coiled and/or include one or more bends therein to conserve space.
In the preferred embodiment, each capillary tube 18 a, 18 b is formed of a conductive material, and thus acts as its own heater 19 a, 19 b by passing current through the tube. The capillary tubes 18 a, 18 b may be any electrically conductive material capable of being resistively heated, while retaining the necessary structural integrity at the operating temperatures experienced by the capillary tubes 18 a, 18 b, and which is non-reactive with the liquid material. Suitable materials for forming the capillary tubes 18 a, 18 b are selected from the group consisting of stainless steel, copper, copper alloys, porous ceramic materials coated with film resistive material, Inconel® available from Special Metals Corporation, which is a nickel-chromium alloy, nichrome, which is also a nickel-chromium alloy, and combinations thereof.
In one embodiment, each capillary tube 18 a, 18 b is a stainless steel capillary tube 18 a, 18 b, a portion of which serves as a heater 19 a, 19 b. The heater 19 a, 19 b is established between electrical leads 26 a, 26 b and an electrical connection 110 adjacent the outlet ends 63 a, 63 b of the capillary tubes 18 a, 18 b. Thus, a direct or alternating current passes along a length of the capillary tube 18 a, 18 b to form the heater 19 a, 19 b. The first and second capillary tubes can be electrically connected in series such that the first and second capillary tubes 18 a, 18 b are heated by passing electrical current from the power source along the first capillary tube, through the electrical connection interconnecting the first and second capillary tubes, and alohg the second capillary tube, such that the electrical current is effective to heat the capillary tubes to a temperature sufficient to volatilize liquid material contained therein as in U.S. Pat. No. 6,715,487 which is incorporated herein in its entirety by reference thereto. In an alternative embodiment, the capillary tubes 18 a, 18 b can be connected in parallel.
Thus, the stainless steel capillary tube 18 a, 18 b is heated by resistance heating. The stainless steel capillary tube 18 a, 18 b is preferably circular in cross section. The capillary tube 18 a, 18 b may be of tubing suitable for use as a hypodermic needle of various gauges. For example, the capillary tube 18 a, 18 b may comprise a 32 gauge needle has an internal diameter of 0.11 mm and a 26 gauge needle has an internal diameter of 0.26 mm.
In another embodiment, the capillary tube 18 a, 18 b may be a non-metallic tube such as, for example, a glass tube. In such an embodiment, the heater 19 a, 19 b is formed of a conductive material capable of being resistively heated, such as, for example, stainless steel, nichrome or platinum wire, arranged along the glass tube. When the heater arranged along the glass tube is heated, liquid material in the capillary tube 18 a, 18 b is heated to a temperature sufficient to at least partially volatilize liquid material in the capillary tube 18 a, 18 b. In other embodiments, one capillary tube 18 a can be stainless steel and one capillary tube 18 b can be a glass tube.
Preferably, as shown in FIG. 2, that electrical leads 26 a, 26 b and the electrical connection 110 are bonded to the metallic capillary tubes 18 a, 18 b. In the preferred embodiment, the electrical leads 26 a, 26 b are brazed to the capillary tubes 18 a, 18 b. Preferably, one electrical lead 26 a is brazed to a first, upstream portion of the first capillary tube 18 a and a second electrical lead 26 b is brazed to an upstream portion of the second capillary tube 18 b as shown in FIG. 2.
In use, once each capillary tube 18 a, 18 b is heated, the liquid material contained within a heated portion of each capillary tube 18 a, 18 b is volatilized and ejected out of the outlet 63 a, 63 b where it expands and mixes with air from one or more air inlets 44 and forms an aerosol in a mixing chamber 46.
Preferably, the electronic smoking article 60 includes at least one air inlet 44 operable to deliver air to the mixing chamber 46. Preferably, the air inlets 44 to the mixing chamber 46 are arranged downstream of the capillary tubes 18 a, 18 b so as to minimize drawing air along the capillary tube and thereby avoid cooling of the capillary tubes 18 a, 18 b during heating cycles. In use, the volatilized material expands out of each capillary tubes 18 a, 18 b and into the mixing chamber 46 where it can mix with air to form an aerosol which is then drawn through the mouth-end insert 20. In the preferred embodiment, the at least one air inlet 44 includes one or two air inlets. Alternatively, there may be three, four, five or more air inlets 44. Altering the size and number of air inlets 44 can also aid in establishing the resistance to draw of the electronic smoking article 60.
In the preferred embodiment, each liquid supply reservoir 14 a, 14 b may include an electrically operated or a mechanically operated valve 40 a, 40 b, shown in FIG. 2. Each valve 40 a, 40 b is operable to maintain the liquid material within the liquid supply, but opens when the electronic smoking article 60 is activated. Preferably, the electronic smoking article is manually activated by pressing a button (pressure switch) 100 (shown in FIG. 1), which opens the valves 40 a, 40 b and simultaneously activates the heaters 19 a, 19 b. In other embodiments, the valves 40 a, 40 b and the heaters 19 a, 19 b can be puff activated, such that when a smoker draws upon the electronic smoking article 60, the puff sensor 16 communicates with the control circuitry 11 to activate the heaters 19 a, 19 b and open the valves 40 a, 40 b.
Preferably, if the button 100 is used to manually activate the electronic smoking article 60, the valve 40 a, 40 b opens when a critical, minimum pressure is reached so as to avoid inadvertent dispensing of liquid material from the liquid supply reservoirs 14 a, 14 b or activating the heaters 19 a, 19 b. Preferably, the pressure required to press the button 100 is high enough such that accidental heating is avoided. Such arrangement avoids activation of the heaters 19 a, 19 b in the absence of liquid being pumped through the capillary tube.
Advantageously, the use of valves 40 a, 40 b also aids in limiting the amount of liquid that is drawn back from each capillary tube upon release of pressure upon the liquid supply reservoir 14 (and/or the switch 44). Withdrawal of liquid from the capillary tube at conclusion of a puff (or activation) is desirous. The presence of residual liquid in the capillary tube at the initiation of a new puff cycle can lead to undesirable sputtering of liquid from the heated capillary tube at the beginning of activation. The valves 40 a, 40 b can be configured to allow a desired, limited amount of drawback to occur, such that drawback of liquid occurs without air being drawn into the liquid supply reservoirs 14 a, 14 b.
Advantageously, each capillary tube 18 a, 18 b is purged once a smoker has stopped drawing on the electronic smoking article 60 or has stopped pushing the button 100 because any liquid remaining in the tube is expelled (volatilized) during heating.
In the preferred embodiment, the power supply 12 includes a battery arranged in the electronic smoking article 60. The heaters 19 a, 19 b can be connected to the battery by the electrical leads 26 a, 26 b. The power supply 12 is operable to apply voltage across the heaters 19 a, 19 b associated with the capillary tubes 18 a, 18 b and volatilize liquid material contained therein according to a power cycle of either a predetermined time period, such as a 2 to 10 second period, or for so long as pressure is applied to the button (pressure switch) 100. The control circuitry 11 can be programmable and can include a microprocessor programmed to carry out functions such as heating the capillary tubes and/or operating the valves. In other embodiments, the control circuitry 11 can include an application specific integrated circuit (ASIC).
Preferably, the electrical contacts or connection between the heaters 19 a, 19 b and the electrical leads 26 a, 26 b are highly conductive and temperature resistant while the heatable portions 19 a, 19 b of the capillary tubes 18 a, 18 b are highly resistive so that heat generation occurs primarily along the heaters 19 a, 19 b and not at the contacts.
The battery can be a Lithium-ion battery or one of its variants, for example a Lithium-ion polymer battery. Alternatively, the battery may be a Nickel-metal hydride battery, a Nickel cadmium battery, a Lithium-manganese battery, a Lithium-cobalt battery or a fuel cell. In that case, preferably, the electronic smoking article 60 is usable by a smoker until the energy in the power supply is depleted. Alternatively, the power supply 12 may be rechargeable and include circuitry allowing the battery to be chargeable by an external charging device. In that case, preferably the circuitry, when charged, provides power for a pre-determined number of puffs, after which the circuitry must be re-connected to an external charging device.
Preferably, the electronic smoking article 60 also includes control circuitry which can be on a printed circuit board 11. Once the button 100 (pressure switch) is pressed, the power supply 12 is activated and supplies power to the heaters 19 a, 19 b. The control circuitry 11 can also include a heater activation light 27 operable to glow when the heaters 19 a, 19 b are activated. Preferably, the heater activation light 27 comprises at least one LED and is at an upstream end 5 (shown in FIG. 1) of the electronic smoking article 60 so that the heater activation light 27 takes on the appearance of a burning coal during a puff. Moreover, the heater activation light 27 can be arranged to be visible to the smoker. In addition, the heater activation light 27 can be utilized for smoking article system diagnostics. The light 27 can also be configured such that the smoker can activate and/or deactivate the light 27 when desired, such that the light 27 would not activate during smoking if desired.
Preferably, when activated, the heaters 19 a, 19 b heat a portion of the capillary tubes 18 a, 18 b for less than about 10 seconds, more preferably less than about 7 seconds. Thus, the power cycle (or maximum puff length) can range in period from about 2 seconds to about 10 seconds (e.g., about 3 seconds to about 9 seconds, about 4 seconds to about 8 seconds or about 5 seconds to about 7 seconds).
In the preferred embodiment, the liquid supply reservoirs 14 a, 14 b each include a liquid material which has a boiling point suitable for use in the electronic smoking article 60. If the boiling point is too high, the heaters 19 a, 19 b will not be able to vaporize liquid in the capillary tubes 18 a, 18 b. However, if the boiling point is too low, the liquid may vaporize without the heaters 19 a, 19 b being activated.
Preferably, the liquid supply reservoirs 14 a, 14 b each contain a different liquid material having different viscosities. The first liquid supply reservoir 14 a can include at least one flavor material. The second liquid supply reservoir 14 b can include at least one tobacco derived ingredient, such as nicotine. Preferably, the liquid material in the second liquid supply reservoir 14 b is more viscous at room temperature than the liquid material in the first liquid supply reservoir 14 a. Moreover, the capillary tube 18 b, associated with the second liquid supply reservoir 14 b, preferably has a larger internal diameter than the capillary tube 18 a associated with the first liquid supply reservoir 14 a. Accordingly, the first capillary tube 18 a produces aerosol having particles ranging in size from about 0.4 micron to about 2 microns depending on the flavor material included in the liquid supply reservoir 14 a and the viscosity thereof. The second capillary tube 18 b produces an aerosol having particles ranging in size from about 0.5 micron to about 1 micron. Advantageously, the electronic smoking article can be configured to form a first aerosol having larger particles for delivery to the mouth and a second aerosol having smaller particles for delivery to the lower respiratory tract if desired.
The second liquid supply reservoir 14 b can include nicotine. The first liquid supply reservoir 14 a can include flavor material, a non-tobacco material and/or may be nicotine-free. For example, the liquid material in the first liquid supply reservoir 14 a may include water, solvents, ethanol, plant extracts and natural or artificial flavors. Preferably, the liquid in each of the first liquid supply reservoir 14 a and the second liquid supply reservoir 14 b can include an aerosol former. Examples of suitable aerosol formers are glycerine and propylene glycol.
As shown in FIG. 2 the electronic smoking article 60 further includes a mouth-end insert 20 having at least two off-axis, preferably diverging outlets 21. Preferably, the mouth-end insert 20 is in fluid communication with the mixing chamber 46 and includes at least two diverging outlets 21. (e.g, 3, 4, 5, or preferably 6 to 10 outlets or more). Preferably, the outlets 21 of the mouth-end insert 20 are located at ends of off-axis passages 23 and are angled outwardly in relation to the longitudinal direction of the electronic smoking article 60 (i.e., divergently). As used herein, the term “off-axis” denotes at an angle to the longitudinal direction of the electronic smoking article 60. Also preferably, the mouth-end insert (or flow guide) 20 includes four outlets uniformly distributed around the mouth-end insert 20 so as to substantially uniformly distribute aerosol in a smoker's mouth during use. Thus, as the aerosol passes into a smoker's mouth, the aerosol enters the mouth and moves in different directions so as to provide a full mouth feel as compared to electronic smoking articles having an on-axis single orifice which directs the aerosol to a single location in a smoker's mouth.
In addition, the outlets 21 and off-axis passages 23 are arranged such that droplets of unaerosolized liquid material carried in the aerosol impact interior surfaces 25 of the mouth-end insert 20 and/or interior surfaces of the off-axis passages 23 such that the droplets are removed or broken apart. In the preferred embodiment, the outlets 21 of the mouth-end insert 20 are located at the ends of the off-axis passages 23 and are angled at 5 to 60° with respect to the central longitudinal axis of the electronic smoking article 60 so as to more completely distribute aerosol throughout a mouth of a smoker during use and to remove droplets.
Preferably, each outlet 21 has a diameter of about 0.015 inch to about 0.090 inch (e.g., about 0.020 inch to about 0.040 inch or about 0.028 inch to about 0.038 inch). The size of the outlets 21 and off-axis passages 23 along with the number of outlets 21 can be selected to adjust the resistance to draw (RTD) of the electronic smoking article 60, if desired.
Preferably, the mouth-end insert 20 is affixed within the outer cylindrical housing 22 of the cartridge 70.
In a preferred embodiment, the electronic smoking article 60 is about the same size as a conventional cigarette. In some embodiments, the electronic smoking article 60 can be about 80 mm to about 110 mm long, preferably about 80 mm to about 100 mm long and about 7 mm to about 8 mm in diameter. For example, in an embodiment, the electronic smoking article is about 84 mm long and has a diameter of about 7.8 mm.
The outer cylindrical housing 22 of the electronic smoking article 60 may be formed of any suitable material or combination of materials. Preferably, the outer cylindrical housing 22 is formed of metal. Examples of suitable materials include metals, alloys, plastics or composite materials containing one or more of those materials, or thermoplastics that are suitable for food or pharmaceutical applications, for example polypropylene, polyetheretherketone (PEEK), ceramic, low density polyethylene (LDPE) and high density polyethylene (HDPE). Preferably, the material is light and non-brittle. The outer cylindrical housing 22 can be any suitable color and/or can include graphics or other indicia printed thereon.
When the word “about” is used in this specification in connection with a numerical value, it is intended that the associated numerical value include a tolerance of ±10% around the stated numerical value. Moreover, when reference is made to percentages in this specification, it is intended that those percentages are based on weight, i.e., weight percentages.
Moreover, when the words “generally” and “substantially” are used in connection with geometric shapes, it is intended that precision of the geometric shape is not required but that latitude for the shape is within the scope of the disclosure. When used with geometric terms, the words “generally” and “substantially” are intended to encompass not only features which meet the strict definitions but also features which fairly approximate the strict definitions.
It will now be apparent that a new, improved, and nonobvious electronic smoking article has been described in this specification with sufficient particularity as to be understood by one of ordinary skill in the art. Moreover, it will be apparent to those skilled in the art that numerous modifications, variations, substitutions, and equivalents exist for features of the electronic smoking article which do not materially depart from the spirit and scope of the invention. Accordingly, it is expressly intended that all such modifications, variations, substitutions, and equivalents which fall within the spirit and scope of the invention as defined by the appended claims shall be embraced by the appended claims.

Claims

We claim:

1. An electronic smoking article comprising:

a first capillary aerosol generator which produces a first aerosol of a first liquid material including flavor material; and

a second capillary aerosol generator which produces a second aerosol of a second liquid material, the second liquid material including nicotine,

wherein the first aerosol has a first particle size distribution and the second aerosol has a second particle size distribution.

2. The electronic smoking article of claim 1, wherein the first capillary aerosol generator comprises:

a first capillary tube having a first capillary inlet and a first capillary outlet, the first capillary inlet in communication with the first liquid material; and

a first heater operable to heat the first capillary tube to a temperature sufficient to volatilize the first liquid material contained within the first capillary tube.

3. The electronic smoking article of claim 2, wherein the second capillary aerosol generator comprises:

a second capillary tube having a second capillary inlet and a second capillary outlet, the second capillary inlet in communication with the second liquid material; and

a second heater operable to heat the second capillary tube to a temperature sufficient to volatilize the second liquid material contained within the second capillary tube.

4. The electronic smoking article of claim 3, wherein the first liquid material and the second liquid material have different room temperature viscosities.

5. The electronic smoking article of claim 3, wherein the first liquid material comprises flavor material and the second liquid material comprises nicotine.

6. The electronic smoking article of claim 3, wherein an internal diameter of the first capillary tube is smaller than an internal diameter of the second capillary tube.

7. The electronic smoking article of claim 3, further comprising:

a power supply operable to apply voltage across the first heater and the second heater;

a mixing chamber downstream of the first capillary tube and the second capillary tube; and

at least one air inlet operable to deliver air into the mixing chamber during drawing on the electronic smoking article.

8. The electronic smoking article of claim 6, wherein each of the first capillary tube and the second capillary tube has an internal diameter of about 0.05 to 0.4 mm and a length of about 5 mm to about 72 mm or about 10 mm to 60 mm.

9. The electronic smoking article of claim 6, wherein each of the first capillary tube and the second capillary tube comprise a stainless steel tube or a non-metallic tube.

10. The electronic smoking article of claim 7, wherein the power supply includes a battery.

11. The electronic smoking article of claim 10, wherein the first heater is connected to the battery by two spaced apart electrical leads and wherein the second heater is connected to the battery by two spaced apart electrical leads.

12. The electronic smoking article of claim 10, wherein the first heater and the second heater are connected in series.

13. The electronic smoking article of claim 7, further including control circuitry operable to control supply of power from the power supply to the first heater and the second heater.

14. The electronic smoking article of claim 13, wherein the control circuitry further includes a heater activation light at an upstream end of the electronic smoking article, the heater activation light operable to light up when the first heater and the second heater are activated.

15. The electronic smoking article of claim 3, further including a first valve between a first pressurized liquid supply and the first capillary inlet.

16. The electronic smoking article of claim 15, further including a second valve between a second outlet of a second pressurized liquid supply and the second capillary inlet.

17. The electronic smoking article of claim 16, wherein the first valve and the second valve are electrically operated valves and the electronic smoking article further includes a pressure switch, the pressure switch operable to send a signal to open the first valve and the second valve and to send a signal to the control circuitry to supply power to the first heater and the second heater.

18. The electronic smoking article of claim 3, further including a puff sensor operable to sense a draw on the electronic smoking article.

19. The electronic smoking article of claim 7, wherein the electronic smoking article includes a first section and a second section and wherein the first section contains the first capillary aerosol generator and the second capillary aerosol generator and the second section contains the power supply and control circuitry operable to control heating of the first and second heaters.

20. The electronic smoking article of claim 19, wherein the first section is replaceable and the second section is reusable.

21. A method of forming an aerosol containing two particle size distributions comprising:

supplying a first liquid containing flavor material to a first capillary tube;

supplying a second liquid containing nicotine to a second capillary tube;

simultaneously heating the first capillary tube and the second capillary tube to a temperature sufficient to volatilize the first liquid and the second liquid to form a first vapor and a second vapor;

mixing the first vapor with air to produce a first aerosol;

mixing the second vapor with air to produce a second aerosol; and

combining the first and second aerosols in a mixing chamber.

22. The method of claim 21, wherein the first aerosol comprises particles ranging in size from about 0.4 micron to about 2 microns.

23. The method of claim 21, wherein the second aerosol comprises particles ranging in size from about 0.5 micron to about 1 micron.

24. The method of claim 21, wherein the heating of the first capillary tube and the heating of the second capillary tube occur within a puff cycle at different times within the puff cycle.

25. The method of claim 21, wherein the heating of the first capillary tube and the heating of the second capillary tube occur within a puff cycle and achieve different temperatures within the puff cycle.