Concentricity for long concentric nebulizers

Abstract

A method for stabilizing and centrally positioning an inner capillary in a concentric nebulizer comprises supporting the inner capillary near the tip of the nebulizer by contacting the nebulizer body against the inner capillary or by interposing a support between the nebulizer body and the inner capillary near the tip. An embodiment of a nebulizing device having stabilized central positioning of its inner capillary is disclosed which comprises an outer capillary with a linear bore and a gas/liquid orifice in a distal tip, a central capillary disposed within the linear bore, and a support sufficiently proximate the orifice to maintain the central capillary substantially centered within the outer capillary adjacent to the orifice. An open volume within the outer capillary between the orifice and the support is dimensioned to enable gas flow to spread substantially evenly around the central capillary.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S. Prov. Pat. Appl. No. 60/757,923 filed Jan. 10, 2006, the disclosure of which is incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

BACKGROUND OF THE INVENTION

Concentric nebulizers have been in use for over 100 years as furnace burners, paint spray guns, medical nebulizers, analytical nebulizers and for many other uses. Concentric nebulizers have a central capillary that usually carries the liquid, and an outer capillary that surrounds the central capillary and usually carries the gas. As gas flows out of the outer capillary, it sucks the liquid out of the inner capillary and creates an aerosol. Ideally, the inner capillary should be perfectly centered in the outer capillary to provide the best gas flow around the inner capillary and produce the best mist.

There are many variations of concentric nebulizers, each developed according to its purpose. But many designs require that the concentric nebulizer should be much longer than wider on the end where the atomized liquid is sprayed out.

The efficiency of the nebulizer relates to many factors such as the gas pressures, gas flow rates, liquid flow rates, liquid viscosity, and others. One factor that is often difficult to deal with is how closely the central capillary sits in the center of the gas orifice in the end of the outer capillary. This is a factor that has a large influence on the consistency of the aerosol produced. Due to the difficulty of holding the central capillary perfectly centered, it is rare that it is actually centered in commercially available concentric nebulizers.

When the central capillary is not concentric, then there will be more gas flow on one side of the gas orifice than on the other side. This will lead to turbulence which will produce larger droplets than occurs with non-turbulent flow. In most applications, smaller droplets are desired.

Analytical concentric nebulizers used in Inductively Coupled Plasma (ICP) and IC/Mass-Spectroscopy (MS) spectrometers are particularly effected by such non-concentricity, as their aerosols must be consistent from one nebulizer to another, and the sensitivity of the spectrometer depends largely on the droplet sizes produced by the nebulizer.

Analytical concentric nebulizers are available from many sources, and are usually made of glass or inert plastics. Due to historical reasons, most analytical nebulizers are made with a long front cylindrical section approximately 6 mm in outside diameter and about 25 mm long, and a back section of various sizes and configurations to attach the liquid and gas lines. This allows the nebulizers to fit most spectrometers without requiring special adapters. There is no other intrinsic reason for the sizes to be used, but the present art is such that most or all are made with this front size and shape. It is desirable to continue using the standard sizes in future designs to allow easy usage of the nebulizers in present systems. It is also desirable to enable concentric nebulizers used for other purposes to be able to have very long bodies while maintaining the central capillary as close as possible to the exact center of the gas orifice.

The present art for analytical nebulizers uses glass blowing, molding and machining techniques to make the nebulizers. They are commonly made of glass, plastic, or non-corrosive materials such as stainless steel. In all present commercially available designs, the inner capillary is attached in the middle or at the back of the nebulizer body and extends forward to the tip of the nebulizer. The strength of the material of the inner capillary is all that holds the inner capillary in place in the center of the outer capillary. In most cases, the inner capillary does not get positioned in the center of the outer capillary as the material is not strong enough to hold the tiny inner capillary exactly in place. In many designs, the inner capillary will vibrate as the gas flows around it, further effecting the quality of the mist.

FIG. 1 and FIG. 2 show cross-sections of glass concentric nebulizer designs that are presently commercially available for analytical usage. For both, there is a liquid sample entry section 103; a connecting point 105 of the central capillary 109 to the main body of the nebulizer; an outer tube portion (outer capillary) 107 that carries the gas flow and comprises the nose of the nebulizer, an inner, central lumen within the central capillary 109 that carries the liquid to the gas orifice at the nebulizer tip 111; and a gas inlet 113 which is typically designed as a barb fitting or as a threaded fitting for the gas input lines. FIG. 1 shows a glass blown design in which the inner capillary 109 is thick at the junction point 105, and very narrow from there to the tip 111. The thin glass tube is very fragile and easy to break. It is also difficult for the central glass tube to remain positioned in the center of the tip. It usually leans to one side in the tip. FIG. 2 shows a glass nebulizer with the inner central capillary 109 ground to a conical shape. This provides a stronger support for the central capillary, but still is not strong enough to keep the capillary 109 centrally placed close to the nebulizer tip 111.

FIG. 3 shows a cross-section of a molded nebulizer presently available for analytical usage. This is a plastic molded design in which a central capillary is made of three separate concentric capillaries, a first central capillary 109, a second central inner capillary 112, and a third central inner capillary 123. This provides more support at the base (connecting junction) 105. However, the innermost capillary 123 is very thin and very soft, and often bends away from the tip 111, producing a very poor mist.

In standard analytical nebulizers, the common practice is to make the nebulizer with a 6 mm OD nose (outer capillary) that is about 25 mm long. With such a long, thin nose, the central liquid passage has been typically very long and very thin, and not rigidly held in place.

It is apparent that the diameter and the unsupported length of the central capillary are critical to determine its strength and ability to be held correctly in the center. If analytical nebulizers were made with a short, thick central capillary, then the mist produced would be more consistent and the nebulizer much less likely to break. However, standardization in equipment receiving nebulizers has resulted in the less optimal long, thin form factor.

Long concentric nebulizers typically are manufactured with long, unsupported, central capillaries. The central capillaries often vibrate during use, causing irregularities in the mist produced. Owing to their length, the central capillaries often break very easily. Should any particle become lodged in the central capillary, it is usually impossible to remove the particle without breaking the central capillary due to the fragility of the central capillary.

BRIEF SUMMARY OF THE INVENTION

The present invention allows the production of concentric nebulizers with better central positioning of an inner central capillary within the nebulizer with minimal complicating factors in the design.

The present invention provides a process and apparatus for stabilizing the central positioning of an inner capillary of concentric nebulizers, optionally along the entire length of the inner capillary but necessarily near the tip of the outer capillary (i.e., near the tip of the nebulizer). This allows the inner central capillary to be more exactly centered in a gas orifice at the tip of the nebulizer, and it dramatically decreases any vibrations in the inner capillary as the gas flows through the outer capillary.

One embodiment of the present method comprises the steps of providing: a body to hold outer and inner capillaries including means to attach gas and liquid supplies to the device, a passage to convey a gas stream, an inner capillary to convey a liquid, and a support in the body near the tip of the nebulizer to hold the inner capillary more centered.

A further embodiment of the invention provides a method for maintaining the centricity of a central capillary of a concentric nebulizer, comprising the steps of providing a concentric nebulizer having an outer capillary, which outer capillary comprises a length, external and internal diameters, a bore, and an inner wall, said outer capillary terminating at a tip and having an orifice in said tip for gas and/or liquid, providing at least one central capillary having external and internal diameters disposed within the outer capillary; and providing a support of the at least one central capillary sufficiently near the orifice to maintain the central capillary centered within the outer capillary and with respect to a center of the orifice.

The support for an inner member comprising a central capillary may be of many various styles and shapes. The support may be in the form of an inner member comprises a central capillary in contact with the nebulizer body near the tip of the nebulizer, or the support may comprise an additional support element interposed between the body of the nebulizer and an inner member comprising a central capillary. The essence is simply that the inner capillary should be supported very close to the nebulizer tip rather than from the back or middle part of the nebulizer body. It can be advantageous to make the inner capillary of larger outside diameter than presently is standard, to allow some portion of the inner capillary to be securely positioned by the inner support. If the inner capillary is too small in outer diameter, then the support may not work as well.

In one embodiment of the invention, a preferred method of support is to have the inner central capillary secured in the body of the nebulizer for the majority of the nebulizer's length, leaving only a small enough portion at the tip unsecured to allow the gas to flow smoothly around the inner capillary as it leaves the gas orifice.

A further embodiment of the invention provides for a nebulizing device comprising a nebulizer body with gas and liquid inputs, an outer capillary having external and internal diameters, a length, a wall, an inner wall surface and a distal tip, a linear bore through the outer capillary having a diameter; a substantially linear, cylindrical, central capillary disposed within the linear bore, said central capillary having an external diameter, an outer surface and at least one substantially linear feature on the outer surface thereof for conveying a gas flow; at least one lumen within the central capillary; a gas/liquid orifice in the tip of the outer capillary; a support positioned in a support region sufficiently proximate the orifice to maintain the central capillary substantially centered within the outer capillary adjacent to the orifice; and an open volume within the outer capillary intermediate the orifice and the support dimensioned to allow the gas flow to spread substantially evenly around the central capillary.

The invention further provides for, within the outer capillary of a nebulizer, a central capillary having a wall, wherein the thickness of the wall tapers without changing a diameter of a central lumen contained within the central capillary along a distance from the support to a point adjacent the orifice, such that at the termination of the central capillary the external diameter of the central capillary is substantially equal to the diameter of the central lumen.

One embodiment of the invention further provides for the support is located entirely in a half of the outer capillary that contains the gas orifice.

Other aspects, features and advantages of the present invention are disclosed in the detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood by reference to the following detailed description of the invention in conjunction with the drawings, of which:

FIGS. 1 and 2 illustrate conventional glass analytical nebulizers currently in production;

FIG. 3 illustrates a conventional perfluoro-alkoxy (PFA), copolymer-resin, analytical nebulizer currently in production;

FIG. 4A illustrates a concentric nebulizer according to an embodiment of the invention with a support at the tip to help center a central capillary;

FIG. 4B illustrates a similar design of support as illustrated in FIG. 4A, but with a nebulizer body similar to that illustrated in FIG. 3;

FIG. 5 illustrates a method of supporting a central capillary by using a wider central capillary fully supported for the majority of the length of the nebulizer, with either a notch in the central capillary or additional holes in the central capillary to convey the gas;

FIGS. 6A and 6B illustrate an insert supporting a first inner central capillary with a smaller, second inner capillary within the first inner central capillary;

FIGS. 7A and 7B illustrate an insert supporting the tip of a central capillary that has been shaped to a point at its tip;

FIGS. 8A-8D illustrate a molded tip of the outer capillary with a non-circular inner surface cross-section, enabling the molded tip to center the central inner capillary while allowing the gas to pass the capillary support;

FIGS. 9A and 9B illustrate a body similar to that illustrated in FIG. 5 with a central capillary fully supported for the majority of the length of the nebulizer, but with a notch on one side to allow the gas to flow to the tip; and

FIGS. 10A and 10B illustrate a body similar to that illustrated in FIG. 5 with a central capillary fully supported for the majority of the length of the nebulizer, but with one or more additional lumens in the central capillary tube to allow the gas to flow to the tip.

DETAILED DESCRIPTION OF THE INVENTION

According to embodiments of the present invention, long concentric nebulizers can be produced with better concentricity than previously possible, which improves the aerosol produced.

It is one of the objectives of the presently disclosed invention to provide for concentric nebulizers with an inner capillary that is very long in length and that is well supported and well held in line with the center of the exit hole of the nebulizer.

The inner capillary can be firmly held centrally in place by a support close to the tip of the nebulizer. However long the nebulizer body is, if the central capillary is well supported, especially at or proximate to the tip of the nebulizer, the tip of the capillary can remain centered. The difficulty in providing support along the length of the central capillary or at the tip of the nebulizer is that the support must be able to allow the gas to pass through it, or the nebulizer will not function. Further, the gas must flow with minimal or no turbulence as it exits the tip of the nebulizer. Turbulence in the gas flow would cause larger droplets to be formed, degrading the mist.

FIGS. 4A and 4B show variations on how a support 15 can be employed according to embodiments of the invention to improve the support of the central, inner capillary. Support 15 can be provided as an insert near the tip of the nebulizer or as a molded part of the inside wall of the tip of the nebulizer.

Referring to FIG. 4A, one embodiment provides for a nebulizer body with gas input 13 and liquid input 3, comprising a back section 5 of various sizes and configurations to attach liquid and gas lines and an outer nose portion 7 of the nebulizer (e.g., a long, front cylindrical section, or outer capillary). This outer portion 7 can have, inter alia, (a) an external diameter 28, (b) a wall, (c) an inner wall surface, (d) a linear bore passing through the outer portion, which bore has an internal diameter, and (e) a distal tip. The nebulizing device of this preferred embodiment may further comprise a substantially linear, cylindrical, inner member 9 disposed within the linear bore, said inner member 9 having an external diameter, an outer surface and having at least one substantially linear feature on the outer surface thereof for conveying a gas flow. Said inner member 9 can comprise a first inner, central capillary. In addition, a second inner capillary 12 may be formed within the inner member 9 for conveying a liquid flow, and a gas/liquid orifice 11 may be located in the tip of the outer nose portion 7 of the nebulizer body. In this preferred embodiment of a nebulizer device according to the invention, a support 15 exists in a support region sufficiently close to the gas/liquid orifice 11 to maintain the second inner capillary 12 substantially centered in the outer nose portion close to the orifice 11. Passages around, beside or through said support 15 exist to allow gas to flow past or through the support region with minimal turbulence, and an open volume 17 exists within the outer portion near the orifice 11, said volume dimensioned to allow the gas flow to spread reasonably evenly around the inner member 9 and second inner capillary 12.

The invention, as depicted in FIG. 4A, also provides further for a device wherein a first inner central capillary 9 is supported by and terminates closely after the support 15, and a second inner central capillary 12 extends beyond the termination of the first central capillary 9 substantially through the volume 17 to terminate near the orifice 11. One exemplary embodiment provides, measured at a cross-section within the first half of the support 15 away from the orifice 11, an inner member 9 having an external diameter of about 2 mm and disposed within said inner member 9 a secondary inner capillary 12 having external diameter about 0.5 mm or less and having an inner diameter about 0.25 mm or less.

In another embodiment, shown in FIG. 4B, the first central capillary 9 contains a secondary inner capillary 12, which extends beyond the termination of the first central capillary 9 substantially through the open volume 17 such that the secondary inner capillary 12 is centered within the outer nose portion 7 and terminates close to the gas/liquid orifice 11. A third central capillary 23 can be disposed outside the first central capillary 9 and can terminate before the support 15 and is not directly supported by the support 15, but the first central capillary 9 is supported directly by the support 15 and terminates close after the support.

Referring still to FIG. 4B, a further exemplary embodiment provides, measured at a cross-section at the beginning end of the outer nose portion 7 away from the end containing the orifice 11, an inner member (or third inner central capillary) 23 having an external diameter about 3.0 mm, wherein disposed within the inner member 23 is a first central capillary 9 having an external diameter about 2.0 mm, and disposed within said first central capillary 9 is a secondary inner capillary 12 having an external diameter about 0.5 mm or less and having an inner diameter about 0.25 mm or less.

A further preferred embodiment, referring still to FIGS. 4A and 4B provides for a nebulizer having a support 15 and a supported region 75. In these examples, the support 15 is positioned entirely in the end of the outer nose portion 7 of the nebulizer that contains the orifice 11.

FIGS. 5 and 9A illustrate how a bore can be provided in said nebulizer body dimensioned to receive a central capillary 9 and to support the capillary 9 along a majority of its length centered in said outer portion 7. If the central capillary has a linear notch along one side, such as notch 19 shown in FIG. 5, the central capillary 9 will be supported by the inner wall of bore 10, and the notch will allow the gas to flow to the tip of the nebulizer. In this example, at least one notch 19 is provided along the outer surface of the central capillary and in communication with the gas input 13 to allow gas to flow from the gas input 13 to the gas/liquid orifice 11 through the at least one notch 19 along the capillary with minimal turbulence. The central capillary 9 is supported by the bore sufficiently close to the orifice 11 to maintain the central capillary centered within the outer portion 7 close to the center of said orifice 11. An expansion space, or open volume 17, can be provided close before the orifice 11.

To allow a non-turbulent gas flow, a support must have sufficiently large holes or other pathways in it for the gas to pass through smoothly. Also, the support must leave some room (open volume) at the tip of the nebulizer to allow the gas flow to spread evenly around the central capillary. FIGS. 4A, 4B and 5 show open volume 17 at the tip of the nebulizer. This open volume 17 must be large enough to allow the flow of the gas to spread reasonably evenly, and the length of this volume must be short enough to maintain support for the central capillary 9. Exact sizes are determined by the materials in use, inter alia.

In some exemplary embodiments of the invention, the outer nose portion 7 of the nebulizer can have a length of about 20 to 40 mm and an external diameter about 6.0 mm.

As long as the cross-sectional space for the gas flow within the support 15 is enough and the final open volume 17 around the terminating tip of the inner capillary 9 is large enough, then the gas flow will remain sufficiently non-turbulent.

FIGS. 6A and 6B illustrate one embodiment that provides for a support 15 with a cross-section similar to a bicycle wheel, i.e., with radial spokes. The spokes are formed of longitudinal fins or vanes, which extend from the outer surface of the central capillary, or from a support hub surrounding the capillary, to the inner surface of the outer capillary 7. FIG. 6A is an expanded detail view of the tip end of an outer capillary 7 with a support 15 holding a first inner central capillary 9, where inside the first inner capillary 9 is disposed a second inner capillary 12. The first inner capillary 9 is supported by the support 15 proximate to the terminating tip of the inner capillary 9, and the smaller second inner capillary 12 extends through the short open volume 17 to the nebulizer tip 11. This minimizes the volume occupied by the capillaries within the open volume 17, thus facilitating the spread of gas flow. FIG. 6B shows a cross-section of FIG. 6A along line 6B-6B, where the cross-section of support 15 is similar to spokes of a bicycle wheel, but with proportionally thicker fin-like supports 16.

FIGS. 7A and 7B show a cross-sectional support similar to that illustrated in FIG. 6A and 6B, but with a different style of central capillary 9. In FIG. 7A, the central capillary 9 is made of a thicker outside dimension and has a tapered tip. The thickness of the central capillary wall tapers without changing the diameter of its lumen or of a secondary inner capillary disposed inside said central capillary 9. In one embodiment, this taper can occur along a distance from the support 15 to the gas orifice 11, such that at the termination of the inner member 9 near the orifice 11 the wall of the inner member 9 is almost a knife-edge and at the termination point the external diameter of the central capillary 9 is substantially equal to the diameter of its lumen or of a secondary inner capillary. At least a portion of the non-tapered part proximate to the nebulizer tip 11 is supported and the tapered part extends the short distance past the support 15 to the tip 11.

Shown in FIG. 7A, wherein the outer portion 7 has an external diameter 28 and an internal wall 4, a support 15 can be inserted about the central capillary and within the outer portion 7, said support 15 having a length and comprising a hub portion 26 that in cross-sectional aspect has an internal diameter approximately equal to the external diameter of the central capillary 9, and said support further comprising, in cross-section, a plurality of fins 16 integral with and extending spoke-like from the hub portion 26 to contact the internal wall of the outer portion 7 of the nebulizer, wherein each fin 16 has a base where the fin integrally connects with the hub portion 26 and a tip where the fin 16 contacts the inner wall 4 of the outer portion 7 of the nebulizer.

With reference to FIG. 6A, a further exemplary embodiment provides, measured at a cross-section within that half of the support 15 away from the orifice 11, a first inner capillary 9 having an external diameter 14 of about 2.0 mm. Disposed within the first inner capillary 9 is a second inner capillary 12 having an inner diameter of about 0.5 mm or less.

With reference to FIG. 7A, another exemplary embodiment provides, measured at a cross-section within that half of the support 15 away from the orifice 11, an inner capillary 9 having an external diameter of about 2.0 mm. However, as one moves along the inner capillary 9 toward the gas orifice 11, the outer diameter of the inner capillary 9 becomes progressively smaller.

In both FIGS. 6B and 7B, the support is shown in cross-section with ten fins 16. The number and thickness of fins 16 in the support 15 is not critical. The critical aspect is that the gas flows with minimal turbulence and at a desired rate. The open space of the cross-sectional shape of the support 15 can be varied depending on the flow rates intended to be used in the operation of the nebulizer.

As shown in FIG. 7B, the fins 16 can have a cross-sectional aspect tapering from relatively greater thickness at their base to relatively lesser thickness at their tip.

FIGS. 8A, 8B, 8C and 8D show different cross-sections, more appropriate for a molded support. FIG. 8A shows how a molded support 15 can be included as part of a molded tip of a nebulizer, with the central capillary 9 pressed into the support. The inner wall 4 of the outer capillary 7 of the nebulizer can be formed or molded such that the formed or molded wall contacts the inner central capillary 9 in a support region 75 close to the orifice 11. The capillary 9 is centrally supported by contact with the molded inner wall of the outer capillary 7 to maintain the inner central capillary 9 centered within the outer capillary 7 close to the orifice 11.

FIGS. 8B, 8C and 8D show various configurations of cross-sections that could be used as a support 15. In all of the configurations shown, there are differences in the cross-sectional area allowed for the gas flow in the support region, so some configurations would be more appropriate for lower gas flows and some for higher gas flows. Referring to FIG. 8B, the inner wall 4 of the outer portion 7 can be formed such that, in cross-section, an open volume shaped as an equilateral polygon, such as, for example, a triangle, is formed within the inner wall 4, and the inner capillary can be disposed, in cross-section, as an incircle of said polygon.

In another embodiment, as shown in FIGS. 8C and 8D, the inner wall can be formed into, in cross-section, a plurality of ridges 30 that project from the inner wall of the outer portion to contact the inner member 9, wherein each of the ridges has a base where the ridge integrally connects with the inner wall of the outer portion and a tip where the ridge contacts the outer surface of the inner member 9, and each ridge runs the length of the support region 75 (see FIG. 8A). The support region 75 formed by the molded inner wall can be three ridges (see, for example, as in FIG. 8C) or six ridges (see, for example, as in FIG. 8D) or any other number of ridges symmetrically disposed about the inner member.

Referring to FIGS. 8A, BB, 8C and 8D, one embodiment of the invention provides, measured at a cross-section within that half of the support 75 away from the orifice 11, an inner member 9 having an external diameter of about 2 mm, and disposed within the inner member a secondary inner capillary having an inner diameter of about 0.5 mm or less.

FIGS. 9A and 9B show details and cross-sections of a nebulizer tip 11 similar to the tip 11 shown in FIG. 5. In FIG. 9A, one embodiment provides for a central capillary 9 that has been inserted into a bore extending through the nebulizer. The central capillary 9 may be glued or press-fit at the back where the liquid input is provided, to prevent the gas from exiting at the liquid input. The central capillary 9 has at least one notch 19 cut from the outer surface of a central capillary 9 such that a cross-sectional profile of the capillary 9 comprises a circle from which a chord segment notch 19 is removed (see FIG. 9B). In one embodiment, said chord segment notch 19 is, at its thickest point, about 4% to 5% of the outer portion external diameter 28. Alternatively, the central capillary 9 may have more than one notch 19, as long as enough of the capillary 9 remains to be properly supported by the inner walls of the bore 10. The notch or notches 19 will extend from the gas input to the terminating tip of the capillary 9, and not all the way back to the liquid input area. The central capillary 9 and bore 10 extending through the nebulizer can each be of a non-circular shape, so long as the central capillary 9 remains supported.

As shown in FIGS. 10A and 10B, an extruded multilumen central capillary 20 can comprise the inner member with a central lumen 22 and at least one non-central lumen 24. The multilumen capillary 20 is a capillary with several holes running along its length rather than one hole in the center. A liquid flow can be conveyed in the central lumen 22 and a gas flow can be conveyed in the at least one non-central lumen 24, said at least one non-central lumen 24 being sized to allow a desired volume of gas to flow at a desired rate with minimal turbulence. If the central extruded capillary 22 is tapered at the tip, then the holes 24 conveying the gas will end before the tip of the nebulizer and allow the gas to spread evenly around the central portion of the capillary in open volume 17. To have the gas flow in the additional holes 24 for the gas, the back portion of the gas holes must be plugged and holes or notches must be provided in the sides of the capillary to allow the gas to flow from the gas input of the body into the holes 24 for the gas in the multilumen central capillary 20.

A bore 10 in said nebulizer body is dimensioned to closely receive said central capillary 20 and to support the inner member by contact along a majority of its length. The bore 10 supports the capillary 20 centered in the bore sufficiently close to the gas/liquid orifice 11 to maintain the central lumen 22 centered within the outer portion 7 close to the center of said orifice 11. In a further exemplary embodiment, the support of said bore is continued along the length of the central capillary 20 to a point a short distance from the orifice 11. Within the inner member 9 a central lumen 22 can be provided and at least one non-central lumen 24 having relatively small diameters. The radius of the capillary 20 diminishes toward the nebulizer tip so that only a radius of the inner member enclosing the central lumen 22 is remaining proximate the orifice 11.

According to embodiments of the present invention, very long nebulizers can be made if they have support for the central capillary 9. The method shown in FIGS. 5, 9A and 10A are easily adapted to unlimited length nebulizers—the support may extend for the entire length of the inner central capillary 9. The capillary can be any length desired, as it is not dependent upon the structural strength of the central capillary 9.

In other embodiments, as shown for example in FIGS. 4A and 6A a short unsupported length of the second inner capillary 12 (or, as shown in FIG. 4B, of the third inner capillary 23) can extend through the open volume 17 toward the orifice 11.

In one preferred embodiment, the nebulizer can have an outer nose portion (i.e., the long, front cylindrical section, or the outer capillary) that can have a length about 25 mm and an external diameter about 6 mm, and a back section of various sizes and configurations to attach the liquid and gas lines.

A method according to the present disclosure maintains smooth gas flow in the nebulizer by providing passages around, beside or through the support that allow the nebulizer gas to flow past or through the support region with minimal turbulence and by providing an open volume comprising a cross-sectional open area and a length near the gas orifice, which volume is large enough to allow the gas flow to spread substantially evenly around the inner capillary near the gas orifice.

The foregoing discussion, for convenience, has referred to gas flowing in the outer capillary and liquid flowing in the inner central capillary (and/or through secondary or tertiary inner central capillaries); however, the same advantages of the invention can be observed in nebulizers in which the gas and liquid flows are switched. The gas may be conveyed in the inner central capillary and the liquid in the outer capillary, although it is more common and more efficient to have the gas outside (flowing within the outer capillary) and the liquid in the center (flowing within the inner capillary).

While the invention has been described in connection with specific methods and apparatus, those skilled in the art will recognize other equivalents to the specific embodiments herein. These and other embodiments of the invention illustrated above are intended by way of example and should not be viewed as limiting the scope of the disclosure or of the claims. The actual scope of the invention is to be limited solely by the scope and spirit of the following claims.

Claims

1. A method for maintaining the centricity of a central capillary of a concentric nebulizer, comprising the steps of:

providing a concentric nebulizer outer capillary, which outer capillary comprises a length, external and internal diameters, a bore, and an inner wall, said outer capillary terminating at a tip and having an orifice in said tip for gas and/or liquid,

providing a first central capillary having external and internal diameters disposed within the outer capillary; and

providing a support of the first central capillary sufficiently near the orifice to maintain the first central capillary centered within the outer capillary and with respect to a center of the orifice.

2. The method of claim 1, further comprising

providing a volume intermediate the support of the central capillary and the orifice; and

providing at least one passage proximate the first central capillary for allowing nebulizer gas to flow into the volume.

3. The method of claim 2, wherein the volume is large enough to allow the gas flow to spread reasonably evenly around the first central capillary before exiting the orifice.

4. The method of claim 1, further comprising

inserting the support about the first central capillary and within the outer capillary, said support having a length and comprising a hub portion that has an internal diameter approximately equal to the external diameter of the first central capillary, and said support further comprising, in cross-sectional aspect, a plurality of fins integral with and extending radially from the hub region for contacting an internal wall of the outer capillary, wherein each fin has a base where the fin integrally connects with the hub portion and a tip where the fin contacts the inner wall of the outer capillary along a length of a support region.

5. The method of claim 4, further comprising

providing fins having a cross-sectional aspect tapering from relatively greater thickness at their base to relatively lesser thickness at their tip.

6. The method of claim 1, further comprising

providing disposed inside the first central capillary a second central capillary,

terminating the first central capillary proximate the support, and

extending the second central capillary beyond the termination of the first central capillary.

7. The method of claim 6, further comprising

providing a third central capillary disposed outside the first central capillary,

terminating the third central capillary on a side of the support opposite the orifice, and

extending the first central capillary beyond the termination of the third central capillary.

8. The method of claim 1, further comprising

forming or molding an inner wall of the outer capillary such that the formed or molded inner wall contacts the first central capillary in a support region proximate to the orifice,

wherein the step of providing a support includes centrally supporting the first central capillary by contact with the formed or molded outer capillary inner wall to maintain the first central capillary centered within the outer capillary adjacent to the orifice.

9. The method of claim 8, further comprising

forming or molding the inner wall of the outer capillary such that an open volume shaped in cross-sectional aspect as an equilateral polygon is formed within, and

disposing the first central capillary, in cross-sectional aspect, as an incircle of said polygon.

10. The method of claim 8, further comprising

forming or molding the inner wall into, in cross-sectional aspect, a plurality of ridges projecting from the inner wall of the outer capillary for supportably contacting the first central capillary, wherein each of the ridges has a base where the ridge integrally connects with the inner wall of the outer capillary and a tip for contacting the outer surface of the first central capillary.

11. The method of claim 10 wherein each ridge runs the length of the support region.

12. The method of claim 10, further comprising

forming the inner wall as a plurality of symmetrically disposed ridges in the support region.

13. The method of claim 1, further comprising

providing the bore in the outer capillary dimensioned to receive the first central capillary and to support the first central capillary along a majority of its length centered in said outer capillary, and

providing a notch or notches along the outer surface of the first central capillary and in fluid communication with the gas input to allow gas to flow from a gas input to the gas/liquid orifice through the notch or notches along said first central capillary with minimal turbulence.

14. The method of claim 13, further comprising

providing at least one notch cut from the outer surface of the first central capillary such that a cross-sectional profile of the first central capillary comprises a circle from which a chord segment is removed.

15. The method of claim 1, wherein the step of providing a first central capillary comprises

providing a multilumen central capillary having a central lumen for conveying a liquid flow and having at least one non-central lumen for conveying a gas, and

wherein the step of providing an outer capillary comprises providing the bore in the outer capillary dimensioned to receive the multilumen central capillary and to support the multilumen central capillary by contact along a majority of its length.

16. The method of claim 15, further comprising

progressively diminishing a radius of the first central capillary in a region proximate the orifice such that the first central capillary comprises only the central lumen adjacent the orifice.

17. The method of claim 1, further comprising

providing a first central capillary having a wall with a thickness, wherein the thickness of the wall tapers without changing a diameter of a central lumen contained within the first central capillary along a distance from the support to a point adjacent the orifice, such that at the termination of the first central capillary the external diameter of the central capillary is substantially equal to the diameter of the central lumen.

18. The method of claim 1, further comprising

maintaining smooth gas flow in the nebulizer by providing passages around, beside or through said support for allowing the gas to flow past or through the support with minimal turbulence and by providing an open volume near the gas orifice, which volume is large enough to allow the gas flow to spread substantially evenly around the central capillary.

19. A nebulizing device comprising

a nebulizer body with gas and liquid inputs,

an outer capillary having external and internal diameters, a length, a wall, an inner wall surface defining a bore and a distal tip,

a substantially linear, cylindrical, first central capillary disposed within the bore, said first central capillary having an external diameter and an outer surface;

at least one lumen within the first central capillary;

a gas/liquid orifice in the tip of the outer capillary;

a support positioned in a support region sufficiently proximate the orifice to maintain the first central capillary substantially centered within the outer capillary adjacent to the orifice; and

an open volume within the outer capillary intermediate the orifice and the support dimensioned to allow the gas flow to spread substantially evenly around the first central capillary.

20. The nebulizing device of claim 19, further comprising

passages around, beside or through said support for allowing gas to flow past or through the support region with minimal turbulence.

21. The nebulizing device of claim 19, wherein

the support comprises a hub portion having an internal diameter approximately equal to the external diameter of the first central capillary, and, in cross-sectional aspect, a plurality of fins integral with and extending radially from the hub region to contact the inner wall surface of the outer capillary, the support being inserted around the first central capillary and within the outer capillary;

wherein each fin has a base where the fin integrally connects with the hub portion and a tip where the fin contacts the inner wall surface of the outer capillary along a length of the support region.

22. The nebulizing device of claim 21, wherein each fin tapers in thickness from relatively greater thickness at its base to relatively lesser thickness at its tip.

23. The nebulizing device of claim 19, further comprising

a second central capillary disposed within the first central capillary, the first central capillary being supported by and terminating proximate the support, and the second central capillary extending beyond the termination of the first central capillary substantially through the volume and terminating adjacent the orifice.

24. The nebulizing device of claim 23, further comprising

a third central capillary disposed outside the first central capillary and terminating on a side of the support opposite the orifice and being not directly supported by the support.

25. The nebulizing device of claim 19, wherein

the outer capillary has an inner wall formed or molded to contact and centrally support the first central capillary along the length of a support region,

wherein the support maintains the first central capillary centered within the outer capillary adjacent to the orifice.

26. The nebulizing device of claim 25, wherein

the inner wall in cross-section is formed as an equilateral polygon, and

inside the polygon, the external diameter of the first central capillary, in cross-section, forms an incircle.

27. The nebulizing device of claim 25, wherein

the support comprises, in cross-section, a plurality of ridges projecting integrally from the inner wall surface of the outer capillary to contact the first central capillary, wherein at least one ridge of the plurality of ridges has a base wherein the ridge is integrally connected with the inner wall surface of the outer capillary and a tip where the ridge contacts the outer surface of the first central capillary.

28. The nebulizing device of claim 27, wherein each ridge runs the length of the support region.

29. The nebulizing device of claim 27, wherein the plurality of ridges are symmetrically disposed in the support region.

30. The nebulizing device of claim 19, wherein

the bore in the outer capillary is dimensioned to receive said first central capillary and to support the first central capillary by contact along a majority of its length, wherein the first central capillary is maintained centered within the outer capillary adjacent to the orifice;

at least one notch is cut along the outer surface of the first central capillary and are in fluid communication with the gas input and the open volume, such that gas can flow from the gas input to the open volume and thereby to the gas/liquid orifice through the at least one notch along said first central capillary with minimal turbulence; and

the support positioned about the first central capillary is continued sufficiently close to the orifice to maintain the first central capillary centered within the outer capillary proximate the center of the orifice.

31. The nebulizing device of claim 30, wherein the at least one notch is cut from the outer surface of the first central capillary such that a cross-sectional profile of the first central capillary comprises a circle from which a chord segment is removed.

32. The nebulizing device of claim 19, wherein

the first central capillary comprises a multilumen central capillary having a central lumen for conveying a liquid flow and at least one non-central lumen for conveying a gas flow; and

the bore in said outer capillary is dimensioned to receive and to support said multilumen capillary by contact along a majority of its length.

33. The nebulizing device of claim 32, wherein

a radius of the multilumen capillary diminishes toward the orifice such that the multilumen capillary comprises only the central lumen proximate and after the end of the support region.

34. The nebulizing device of claim 19, wherein

the first central capillary has a wall having a thickness, wherein the thickness of the wall tapers without changing a diameter of the lumen contained within the first central capillary along a distance from the support to a point adjacent the orifice, such that at the termination of the first central capillary the external diameter of the first central capillary is substantially equal to the diameter of the lumen.

35. The nebulizing device of claim 19, wherein

the support is located entirely in a half of the outer capillary that contains the orifice.