Abstract:
An ultrasound apparatus capable of mixing and/or atomizing fluids is disclosed. The apparatus includes a horn having an internal chamber, containing a plurality free members, through which fluids to be atomized and/or mixed flow. Connected to the horn&#39;s proximal end, a transducer powered by a generator induces ultrasonic vibrations within the horn. Traveling down the horn from the transducer, the ultrasonic vibrations induce the release of ultrasonic energy into the fluids to be atomized and/or mixed as they travel through the internal chamber. As the ultrasonic vibrations travel through the chamber, the fluids within the chamber are agitated and/or begin to cavitate, while the free member moves abollt the chamber, thereby mixing the fluids. Upon reaching the front wall of the chamber, the ultrasonic vibrations echo off the front wall and pass through the fluids within the chamber a second time, further mixing the fluids.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Application is a division of U.S. patent application Ser. No. 12/028,876, filed Feb. 11, 2008, the teachings of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an apparatus utilizing ultrasonic waves traveling through a horn and/or resonant structure to atomize, assist in the atomization of, and/or mix fluids passing through the horn and/or resonant structure. 
         [0004]    2. Background Art 
         [0005]    Liquid atomization is a process by which a liquid is separated into small droplets by some force acting on the liquid, such as ultrasound. Exposing a liquid to ultrasound creates vibrations and/or cavitations within the liquid that break it apart into small droplets. U.S. Pat. Nos. 4,153,201 to Berger et al., 4,655,393 to Berger, and 5,516,043 to Manna et al. describe examples of atomization systems utilizing ultrasound to atomize a liquid. These devices possess a tip vibrated by ultrasonic waves passing through the tip. Within the tips are central passages that carry the liquid to be atomized. The liquid within the central passage is driven towards the end of the tip by some force acting upon the liquid. Upon reaching the end of the tip, the liquid to be atomized is expelled from tip. Ultrasonic waves emanating from the front of the tip then collide with the liquid, thereby breaking the liquid apart into small droplets. Thus, the liquid is not atomized until after it leaves the ultrasound tip because only then is the liquid exposed to collisions with ultrasonic waves. 
       SUMMARY OF THE INVENTION 
       [0006]    An ultrasound apparatus capable of mixing and/or atomizing fluids is disclosed. The apparatus comprises a horn having an internal chamber including a back wall, a front wall, and at least one side wall, at least one free member within the internal chamber, a radiation surface at the horn&#39;s distal end, at least one channel opening into the chamber, and a channel originating in the front wall of the internal chamber and terminating in the radiation surface. Connected to the horn&#39;s proximal end, a transducer powered by a generator induces ultrasonic vibrations within the horn. Traveling down the horn from the transducer to the horn&#39;s radiation surface, the ultrasonic vibrations induce the release of ultrasonic energy into the fluids to be atomized and/or mixed as they travel through the horn&#39;s internal chamber and exit the horn at the radiation surface. As the ultrasonic vibrations travel through the chamber, the fluids within the chamber are agitated and/or begin to cavitate, thereby mixing the fluids. The ultrasonic vibrations also induce the free members to move about the chamber. The motion of the free member further mixes the fluids passing through the chamber. 
         [0007]    As with typical pressure driven fluid atomizers, the ultrasound atomization and/or mixing apparatus is capable of utilizing pressure changes within the fluids passing through the apparatus to drive atomization. The fluids to be atomized and/or mixed enter the apparatus through one or multiple channels opening into the internal chamber. The fluids then flow through the chamber and into a channel extending from the chamber&#39;s front wall to the radiation surface. If the channel originating in the front wall of the internal chamber is narrower than the chamber, the pressure of the fluids flowing through the channel decreases and the fluids&#39; velocity increases. Because the fluids&#39; kinetic energy is proportional to velocity squared, the kinetic energy of the fluids increases as they flow through the channel. The pressure of the fluids is thus converted to kinetic energy as the fluids flow through the channel. Breaking the attractive forces between the molecules of the fluids, the increased kinetic energy of the fluids causes the fluids to atomize as they exit the horn at the radiation surface. 
         [0008]    By agitating and/or inducing cavitations within fluids passing through the internal chamber and/or inducing the free member within the chamber to move, ultrasonic energy emanating from various points of the atomization and/or mixing apparatus thoroughly mixes fluids as they pass through the internal chamber. When the proximal end of the horn is secured to an ultrasound transducer, activation of the transducer induces ultrasonic vibrations within the horn. 
         [0009]    The vibrations can be conceptualized as ultrasonic waves traveling from the proximal end to the distal end of horn. As the ultrasonic vibrations travel down the length of the horn, the horn contracts and expands. However, the entire length of the horn is not expanding and contracting. Instead, the segments of the horn between the nodes of the ultrasonic vibrations (points of minimum deflection or amplitude) are expanding and contracting. The portions of the horn lying exactly on the nodes of the ultrasonic vibrations are not expanding and contracting. Therefore, only the segments of the horn between the nodes are expanding and contracting, while the portions of the horn lying exactly on nodes are not moving. It is as if the ultrasound horn has been physically cut into separate pieces. The pieces of the horn corresponding to nodes of the ultrasonic vibrations are held stationary, while the pieces of the horn corresponding to the regions between nodes are expanding and contracting. If the pieces of the horn corresponding to the regions between nodes were cut up into even smaller pieces, the pieces expanding and contracting the most would be the pieces corresponding to the antinodes (points of maximum deflection or amplitude) of the ultrasonic vibrations passing through horn. 
         [0010]    The amount of mixing that occurs within the chamber may be adjusted by changing the locations of the chamber&#39;s front and back walls with respect to ultrasonic vibrations passing through the horn. As the horn expands and contracts, the back wall of the chamber moves forwards and backwards as to induce ultrasonic vibrations in the fluids within the chamber. As the back wall moves forward it hits the fluids. Striking the fluids like a mallet hitting a gong, the back wall induces ultrasonic vibrations that travel through the fluids. The vibrations traveling through the fluids possess the same frequency as the ultrasonic vibrations traveling through horn. The farther forwards and backwards the back wall of the chamber moves, the more forcefully the back wall strikes the fluids within the chamber and the higher the amplitude of the ultrasonic vibrations within the fluids. Increasing the amplitude of the ultrasonic vibrations increases the degree to which the fluids within the chamber are agitated and/or cavitated. 
         [0011]    When the ultrasonic vibrations traveling through the fluids within the chamber strike the front wall of the chamber, the front wall compresses forwards. The front wall then rebounds backwards, strikes the fluids within the chamber, and thereby creates an echo within the fluids of the ultrasonic vibrations that struck the front wall. If the front wall of the chamber is struck by an antinode of the ultrasonic vibrations traveling through chamber, then the front wall will move as far forward and backward as is possible. Consequently, the front wall will strike the fluids within the chamber more forcefully and thus generate an echo with the largest possible amplitude. If, however, the ultrasonic vibrations passing through the chamber strike the front wall of the chamber at a node, then the front wall will not be forced forward because there is no movement at a node. Consequently, an ultrasonic vibration striking the front wall at a node will not produce an echo. 
         [0012]    Positioning the front and back walls of the chamber such that at least one point on both, preferably their centers, lie approximately on antinodes of the ultrasonic vibrations passing through the chamber maximizes the amount of mixing occurring within the chamber. Moving the back wall of the chamber away from an antinode and towards a node decreases the amount of mixing induced by ultrasonic vibrations emanating from the back wall. Likewise, moving the front wall of the chamber away from an antinode and towards a node decreases the amount of mixing induced by ultrasonic vibrations echoing off the front wall. Therefore, positioning the front and back walls of the chamber such that center of both lie on nodes of the ultrasonic vibrations passing through the chamber minimizes the amount of mixing within the chamber. 
         [0013]    Ultrasonic vibrations emanating from the back wall and/or echoing off the front wall of the chamber may induce the free member within the chamber to move about the chamber. Traveling through the chamber, the ultrasonic vibrations strike the free member and push it in the direction of the vibrations. As the free member moves about the chamber it mechanically agitates the fluids within chamber causing the fluids to mix. The degree to which the free member moves when struck by the vibrations traveling through the chamber is proportional to the amplitude of the vibrations. As such, increasing the amplitude of the vibrations increases the motion of the free member and thereby increases the amount in which the fluids passing through the chamber are mixed. In addition or in the alternative to inducing the free member within the chamber to move, the ultrasonic vibrations striking the free member may be reflected off the free member in a random direction. As such, the free member within the chamber may disturb the ultrasonic vibrations&#39; pattern of motion between the walls of the chamber. 
         [0014]    The amount of mixing that occurs within the chamber may also be adjusted by controlling the volume of the fluids within the chamber. Ultrasonic vibrations within the chamber may cause atomization of the fluids. As the fluids atomize, their volumes increase which may cause the fluids to separate. However, if the fluids completely fill the chamber, then there is no room in the chamber to accommodate an increase in the volume of the fluids. Consequently, the amount of atomization occurring within the chamber when the chamber is completely filled with the fluids will be decreased and the amount of mixing increased. 
         [0015]    The mixing occurring within the chamber may also be enhanced by including an ultrasonic lens within the front wall of the chamber. Ultrasonic vibrations striking the lens within the front wall of the chamber are directed to reflect back into the chamber in a specific manner depending upon the configuration of the lens. For instance, a lens within the front wall of the chamber may contain a concave portion. Ultrasonic vibrations striking the concave portion of the lens would be reflected towards the side walls. Upon impacting the side walls, the reflected ultrasonic vibrations would be reflected again, and would thus echo throughout the chamber. If the concaved portion or portions within the lens form an overall parabolic configuration in at least two dimensions, then the ultrasonic vibrations echoing off the lens and/or the energy they carry may be focused towards the focus of the parabola. 
         [0016]    In combination or in the alternative, the lens within the front wall of the chamber may also contain a convex portion. Again, ultrasonic vibrations emitted from the chamber&#39;s back wall striking the lens within the front wall would be directed to reflect back into and echo throughout the chamber in a specific manner. However, instead of being directed towards a focal point as with a concave portion, the ultrasonic vibrations echoing off the convex portion are reflected in a dispersed manner towards the side walls of the chamber. Upon reaching the chamber&#39;s side walls, the ultrasonic vibrations reflect off the side walls. If the angle of deflection off the side wall of the chamber is sufficiently great, the ultrasonic vibrations may travel towards and reflect off different a side wall of the chamber. Thus, the inclusion of an ultrasonic lens within the front wall of the chamber containing a convex portion increases the amount of echoing within the chamber. Increasing the amount of echoing, in turn, increases the amount of ultrasonic vibrations agitating, cavitating, and/or colliding against the fluids within the chamber, thereby enhancing the mixing of the fluids within the chamber. 
         [0017]    In combination or in the alternative, the back wall of the chamber may also contain an ultrasonic lens possessing concave and/or convex portions. Such portions within the back wall lens of the chamber function similarly to their front wall lens equivalents, except that in addition to directing and/or focusing echoing ultrasonic vibrations, they also direct and/or focus the ultrasonic vibrations as they are emitted into the chamber. 
         [0018]    Because the ultrasonic vibrations traveling between the walls of the chamber push the free member in the direction the ultrasonic vibrations travel, the conformation of the lenses within the front and/or back walls of the chamber may influence the motion of the free member about the chamber. If the front or back wall contains an ultrasonic lens with a concave portion or portions that form an overall parabolic configuration in at least two dimensions, the ultrasonic vibrations may converge at the parabola&#39;s focus and then diverge as the vibrations travel from one wall towards the opposite wall. As such, the ultrasonic vibrations may induce the free member to travel towards the focus as it moves from one wall towards the opposite wall. If the front and back wall each contain a lens that forms an overall parabolic configuration in at least two dimensions with different foci, then the free member may travel primarily about the foci, consistently moving towards one focus and away from the other. If the parabolas share a common focus, then the free member may travel primarily about the single focus, consistently moving towards and away from it. 
         [0019]    If the front or back wall contains a lens with a convex portion, the ultrasonic vibrations may be dispersed throughout the internal chamber. As such, the ultrasonic vibrations may induce the free member to travel randomly about the chamber as it moves from one wall towards the opposite wall. Thus, if the front and/or back walls of the chamber contain lenses with a convex portion, then the free member may travel randomly about the chamber as it moves back-and-forth between the front and back walls. 
         [0020]    The amount of mixing occurring within the internal chamber may be controlled by adjusting the amplitude of the ultrasonic vibrations traveling down the length of the horn. Increasing the amplitude of the ultrasonic vibrations increases the degree to which the fluids within the chamber are agitated and/or cavitated. If the horn is ultrasonically vibrated in resonance by a piezoelectric transducer driven by an electrical signal supplied by a generator, then increasing the voltage of the electrical signal will increase the amplitude of the ultrasonic vibrations traveling down the horn. 
         [0021]    As with typical pressure driven fluid atomizers, the ultrasound atomization apparatus utilizes pressure changes within the fluid to create the kinetic energy that drives atomization. Unfortunately, pressure driven fluid atomization can be adversely impacted by changes in environmental conditions. Most notably, a change in the pressure of the environment into which the atomized fluids is to be sprayed may decrease the level of atomization and/or distort the spray pattern. As a fluid passes through a pressure driven fluid atomizer, it is pushed backwards by the pressure of the environment. Thus, the net pressure acting on the fluid is the difference of the pressure pushing the fluid through the atomizer and the pressure of the environment. It is the net pressure of the fluid that is converted to kinetic energy. Thus, as the environmental pressure increases, the net pressure decreases, causing a reduction in the kinetic energy of the fluid exiting the horn. An increase in environmental pressure, therefore, reduces the level of fluid atomization. 
         [0022]    A counteracting increase in the kinetic energy of the fluid may be induced from the ultrasonic vibrations emanating from the radiation surface. Like the back wall of the internal chamber, the radiation surface is also moving forwards and backwards when ultrasonic vibrations travel down the length of the horn. Consequently, as the radiation surface moves forward it strikes the fluids exiting the horn and the surrounding air. Striking the exiting fluids and surrounding air, the radiation surface emits, or induces, vibrations within the exiting fluids. As such, the kinetic energy of the exiting fluids increases. The increased kinetic energy further atomizes the fluids exiting at the radiation surface, thereby counteracting a decrease in atomization caused by changing environmental conditions. 
         [0023]    The increased kinetic energy imparted on the fluids by the movement of the radiation surface can be controlled by adjusting the amplitude of the ultrasonic vibrations traveling down the length of the horn. Increasing the amplitude of the ultrasonic vibrations increases the amount of kinetic energy imparted on the fluids as they exit at the radiation surface. Consequently, increasing the amplitude of the ultrasonic vibrations may increase the degree to which the fluids are atomized after they exit the horn. 
         [0024]    As with increases in environmental pressure, decreases in environmental pressure may adversely impact the atomized spray. Because the net pressure acting on the fluids is converted to kinetic energy and the net pressure acting on the fluids is the difference of the pressure pushing the fluids through the atomizer and the pressure of the environment, decreasing the environmental pressure increases the kinetic energy of the fluids exiting a pressure driven atomizer. Thus, as the environmental pressure decreases, the exiting velocity of the fluids increases. Exiting the atomizer at a higher velocity, the atomized fluid droplets move farther away from the atomizer, thereby widening the spray pattern. Changing the spray pattern may lead to undesirable consequences. For instance, widening the spray pattern may direct the atomized fluids away from their intended target and/or towards unintended targets. Thus, a decrease in environmental pressure may result in a detrimental un-focusing of the atomized spray. 
         [0025]    Adjusting the amplitude of the ultrasonic waves traveling down the length of the horn may be useful in focusing the atomized spray produced at the radiation surface. Creating a focused spray may be accomplished by utilizing the ultrasonic vibrations emanating from the radiation surface to confine and direct the spray pattern. Ultrasonic vibrations emanating from the radiation surface may direct and confine the vast majority of the atomized spray produced within the outer boundaries of the radiation surface. The level of confinement obtained by the ultrasonic vibrations emanating from the radiation surface depends upon the amplitude of the ultrasonic vibrations traveling down the horn. As such, increasing the amplitude of the ultrasonic vibrations passing through the horn may narrow the width of the spray pattern produced; thereby focusing the spray. For instance, if the spray is fanning too wide, increasing the amplitude of the ultrasonic vibrations may narrow the spray pattern. Conversely, if the spray is too narrow, then decreasing the amplitude of the ultrasonic vibrations may widen the spray pattern. 
         [0026]    Changing the geometric conformation of the radiation surface may also alter the shape of the spray pattern. Producing a roughly column-like spray pattern may be accomplished by utilizing a radiation surface with a planar face. Generating a spray pattern with a width smaller than the width of the horn may be accomplished by utilizing a tapered radiation surface. Further focusing of the spray may be accomplished by utilizing a concave radiation surface. In such a configuration, ultrasonic waves emanating from the concave radiation surface may focus the spray through the focus of the radiation surface. 
         [0027]    If it is desirable to focus, or concentrate, the spray produced towards the inner boundaries of the radiation surface, but not towards a specific point, then utilizing a radiation surface with slanted portions facing the central axis of the horn may be desirable. Ultrasonic waves emanating from the slanted portions of the radiation surface may direct the atomized spray inwards, towards the central axis. There may, of course, be instances where a focused spray is not desirable. For instance, it may be desirable to quickly apply an atomized liquid to a large surface area. In such instances, utilizing a convex radiation surface may produce a spray pattern with a width wider than that of the horn. The radiation surface utilized may possess any combination of the above mentioned configurations such as, but not limited to, an outer concave portion encircling an inner convex portion and/or an outer planar portion encompassing an inner conical portion. Inducing resonating vibrations within the horn facilitates the production of the spray patterns described above, but may not be necessary. 
         [0028]    It should be noted and appreciated that other benefits and/or mechanisms of operation, in addition to those listed, may be elicited by devices in accordance with the present invention. The mechanisms of operation presented herein are strictly theoretical and are not meant in any way to limit the scope this disclosure and/or the accompanying claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIGS. 1   a  and  1   b  illustrate cross-sectional views of an embodiment of the ultrasound atomization and/or mixing apparatus. 
           [0030]      FIG. 2  illustrates a cross-sectional view of an alternative embodiment of the ultrasound atomizing and/or mixing apparatus wherein the back wall and front walls contain ultrasonic lenses with a convex portion. 
           [0031]      FIGS. 3   a - 3   e  illustrate alternative embodiments of the radiation surface. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]    Preferred embodiments of the ultrasound atomization and/or mixing apparatus are illustrated throughout the figures and described in detail below. Those skilled in the art will immediately understand the advantages for mixing and/or atomizing material provided by the atomization and/or mixing apparatus upon review. 
         [0033]      FIGS. 1   a  and  1   b  illustrate an embodiment of the ultrasound atomization and/or mixing apparatus comprising a horn  101  and an ultrasound transducer  102  attached to the proximal surface  117  of horn  101  powered by generator  116 . As ultrasound transducers and generators are well known in the art they need not and will not be described in detail herein. Ultrasound horn  101  comprises a proximal surface  117 , a radiation surface  111  opposite proximal end  117 , and at least one radial surface  118  extending between proximal surface  117  and radiation surface  111 . Within horn  101  is an internal chamber  103  containing a back wall  104 , a front wall  105 , at least one side wall  113  extending between back wall  104  and front wall  105 , and ultrasonic lenses  122  and  126  within back wall  104  and front wall  105 , respectively. 
         [0034]    As to induce vibrations within horn  101 , ultrasound transducer  102  may be mechanically coupled to proximal surface  117 . Mechanically coupling horn  101  to transducer  102  may be achieved by mechanically attaching (for example, securing with a threaded connection), adhesively attaching, and/or welding horn  101  to transducer  102 . Other means of mechanically coupling horn  101  and transducer  102 , readily recognizable to persons of ordinary skill in the art, may be used in combination with or in the alternative to the previously enumerated means. Alternatively, horn  101  and transducer  102  may be a single piece. When transducer  102  is mechanically coupled to horn  101 , driving transducer  102  with an electrical signal supplied from generator  116  induces ultrasonic vibrations  114  within horn  101 . If transducer  102  is a piezoelectric transducer, then the amplitude of the ultrasonic vibrations  114  traveling down the length of horn  101  may be increased by increasing the voltage of the electrical signal driving transducer  102 . 
         [0035]    As the ultrasonic vibrations  114  travel down the length of horn  101 , back wall  104  oscillates back-and-forth. The back-and-forth movement of back wall  104  induces the release of ultrasonic vibrations from lens  122  into the fluid inside chamber  103 . Positioning back wall  104  such that at least one point on lens  122  lies approximately on an antinode of the ultrasonic vibrations  114  passing through horn  101  may maximize the amount and/or amplitude of the ultrasonic vibrations emitted into the fluid in chamber  103 . Preferably, the center of lens  122  lies approximately on an antinode of the ultrasonic vibrations  114 . The ultrasonic vibrations emanating from lens  122 , represented by arrows  119 , travel towards the front of chamber  103 . When the ultrasonic vibrations  119  strike lens  126  within front wall  105  they echo off lens  126 , and thus are reflected back into chamber  103 . The reflected ultrasonic vibrations  119  then travel towards back wall  104 . Traveling towards front wall  105  and then echoing back towards back wall  104 , ultrasonic vibrations  119  travel back and forth through chamber  103  in an undisturbed echoing pattern. As to maximize the echoing of vibrations  119  off lens  126 , it may be desirable to position front wall  105  such that at least one point on lens  126  lies on an antinode of the ultrasonic vibrations  114 . Preferably, the center of lens  126  lies approximately on an antinode of the ultrasonic vibrations  114 . 
         [0036]    The specific lenses illustrated in  FIG. 1   a  contain concave portions. If the concave portion  123  of lens  122  within back wall  104  form an overall parabolic configuration in at least two dimensions, then the ultrasonic vibrations depicted by arrows  119  emanating from the lens  122  travel in an undisturbed pattern of convergence towards the parabola&#39;s focus  124 . As the ultrasonic vibrations  119  converge at focus  124 , the ultrasonic energy carried by vibrations  119  may become focused at focus  124 . After converging at focus  124 , the ultrasonic vibrations  119  diverge and continue towards front wall  105 . After striking the concave portion  125  of lens  126  within front wall  105 , ultrasonic vibrations  119  are reflected back into chamber  103 . If concave portion  125  form an overall parabolic configuration in at least two dimensions, the ultrasonic vibrations  119  echoing backing into chamber  103  may travel in an undisturbed pattern of convergence towards the parabola&#39;s focus. The ultrasonic energy carried by the echoing vibrations may become focused at the focus of the parabola formed by the concave portions  125 . Converging as they travel towards front wall  105  and then again as they echo back towards back wall  104 , ultrasonic vibrations  119  travel back and forth through chamber  103  in an undisturbed, converging echoing pattern. 
         [0037]    In the embodiment illustrated in  FIG. 1   a  the parabolas formed by concave portions  123  and  125  have a common focus  124 . In the alternative, the parabolas may have different foci. However, by sharing a common focus  124 , the ultrasonic vibrations  119  emanating and/or echoing off the parabolas and/or the energy the vibrations carry may become focused at focus  124 . The fluids passing through chamber  103  are therefore exposed to the greatest concentration of the ultrasonic agitation, cavitation, and/or energy at focus  124 . Consequently, the ultrasonically induced mixing of the fluids is greatest at focus  124 . Positioning focus  124 , or any other focus of a parabola formed by the concave portions  123  and/or  125 , at point downstream of the entry of at least two fluids into chamber  103  may maximize the mixing of the fluids entering chamber  103  upstream of the focus. 
         [0038]    Ultrasonic vibrations  119  emanating from lens  122  within back wall  104  and/or echoing off lens  126  within front wall  105  may induce free members  127  to move about chamber  103 . Traveling through chamber  103 , ultrasonic vibrations  119  strike free members  127  and push them in the direction of vibrations  119 . As free members  127  move about chamber  103  they mechanically agitate the fluids within chamber causing the fluids to mix. 
         [0039]    In the embodiment illustrated in  FIG. 1   a  the parabolas formed by concave portions  123  and  125  have a common focus  124 . In the alternative, the parabolas may have different foci. However, by sharing a common focus  124 , the ultrasonic vibrations  119  emanating and/or echoing off the parabolas and/or the energy the vibrations carry may become focused at focus  124 . The fluids passing through chamber  103  are therefore exposed to the greatest concentration of the ultrasonic agitation, cavitation, and/or energy at focus  124 . Furthermore because the parabolas share a common focus, free members  127  may travel primarily about focus  124 , consistently moving towards and away from it. Consequently, the mixing of the fluids induced by the motions of the free members  127  and/or ultrasonic vibrations  119  is greatest at and/or about focus  124 . Positioning focus  124 , or any other focus of a parabola formed by the concave portions  123  and/or  125 , at point downstream of the entry of at least two fluids into chamber  103  may maximize the mixing of the fluids entering chamber  103  upstream of the focus. 
         [0040]    Though the specific embodiment of the free members depicted in  FIG. 1  are spherical, other geometric configurations are equally possible such as, but not limited to, cylindrical, pyramidal, rectangular, polygonal, or any combination thereof. Furthermore, instead of using three free members as depicted, any number of mixing members may be used. As to prevent the free members from exiting the internal chamber of the horn, it may be desirable to use free members incapable of passing through the channels leading into and/or out of the internal chamber. In the alternative or in combination, screens, meshes, gates, and/or similar structures may be used to prevent the passage of the free members into and/or through the channels within the horn. Preferably, the free members are constructed from a material that is not completely transparent to ultrasonic vibrations. 
         [0041]    The fluids to be atomized and/or mixed enter chamber  103  of the embodiment depicted in  FIG. 1  through at least one channel  109  originating in radial surface  118  and opening into chamber  103 . Preferably, channel  109  encompasses a node of the ultrasonic vibrations  114  traveling down the length of the horn  101  and/or emanating from lens  122 . In the alternative or in combination, channel  109  may originate in radial surface  118  and open at back wall  104  into chamber  103 . Upon exiting channel  109 , the fluids flow through chamber  103 . The fluids then exit chamber  103  through channel  110 , originating within front wall  105  and terminating within radiation surface  111 . 
         [0042]    As the fluids to be atomized pass through channel  110 , the pressure of the fluids decreases while their velocity increases. Thus, as the fluids flow through channel  110 , the pressure acting on the fluids is converted to kinetic energy. If the fluids gain sufficient kinetic energy as they pass through channel  110 , then the attractive forces between the molecules of the fluids may be broken, causing the fluids to atomize as they exit channel  110  at radiation surface  111 . If the fluids passing through horn  101  are to be atomized by the kinetic energy gained from their passage through channel  110 , then the maximum height (h) of chamber  103  should be larger than maximum width (w) of channel  110 . Preferably, the maximum height of chamber  103  should be approximately 200 times larger than the maximum width of channel  110  or greater. 
         [0043]    It is preferable that least one point on radiation surface  111  lies approximately on an antinode of the ultrasonic vibrations  114  passing through horn  101 . 
         [0044]    As to simplify manufacturing, ultrasound horn  101  may further comprise cap  112  attached to its distal end. Cap  112  may be mechanically attached (for example, secured with a threaded connector), adhesively attached, and/or welded to the distal end of horn  101 . Other means of attaching cap  112  to horn  101 , readily recognizable to persons of ordinary skill in the art, may be used in combination with or in the alternative to the previously enumerated means. Comprising front wall  105 , channel  110 , and radiation surface  111 , a removable cap  112  permits the level of fluid atomization and/or the spray pattern produced to be adjusted depending on need and/or circumstances. For instance, the width of channel  110  may need to be adjusted to produce the desired level of atomization with different fluids. The geometrical configuration of the radiation surface may also need to be changed as to create the appropriate spray pattern for different applications. Attaching cap  112  to the present invention at approximately a nodal point of the ultrasonic vibrations  114  passing through horn  101  may help prevent the separation of cap  112  from horn  101  during operation. 
         [0045]    It is important to note that fluids of different temperatures may be delivered into chamber  103  as to improve the atomization of the fluid exiting channel  110 . This may also change the spray volume, the quality of the spray, and/or expedite the drying process of the fluid sprayed. 
         [0046]    Alternative embodiments of an ultrasound horn  101  in accordance with the present invention may possess a single channel  109  opening within side wall  113  of chamber  103 . If multiple channels  109  are utilized, they may be aligned along the central axis  120  of horn  101 , as depicted in  FIG. 1   a . Alternatively or in combination, channels  109  may be located on different platans, as depicted in  FIG. 1   a , and/or the same platan, as depicted in  FIG. 1   b.    
         [0047]    Alternatively or in combination, the fluids to be atomized and/or mixed may enter chamber  103  through a channel  121  originating in proximal surface  117  and opening within back wall  104 , as depicted in  FIG. 1   a . If the fluids passing through horn  101  are to be atomized by the kinetic energy gained from their passage through channel  110 , then the maximum width (w′) of channel  121  should be smaller than the maximum height of chamber  103 . Preferably, the maximum height of chamber  103  should be approximately twenty times larger than the maximum width of channel  121 . 
         [0048]    A single channel may be used to deliver the fluids to be mixed and/or atomized into chamber  103 . When horn  101  includes multiple channels opening into chamber  103 , atomization of the fluids may be improved be delivering a gas into chamber  103  through at least one of the channels. 
         [0049]    Horn  101  and chamber  103  may be cylindrical, as depicted in  FIG. 1 . Horn  101  and chamber  103  may also be constructed in other shapes and the shape of chamber  103  need not correspond to the shape of horn  101 . 
         [0050]      FIG. 2  illustrates a cross-sectional view of an alternative embodiment of the ultrasound atomizing and/or mixing apparatus wherein lens  122  within back wall  104  and lens  126  within front wall  105  contain convex portions  201  and  202 , respectively. Ultrasonic vibrations emanating from convex portion  201  of lens  122  travel in a dispersed reflecting pattern towards front wall  105  in the following manner: The ultrasonic vibrations are first directed towards side wall  113  at varying angles of trajectory. The ultrasonic vibrations then reflect off side wall  113 . 
         [0051]    Depending upon the angle at which the ultrasonic vibrations strike side wall  113 , they may be reflected through central axis  120  and travel in an undisturbed reflecting pattern towards front wall  105 . However, if the vibrations emanating from lens  122  strike side wall  113  at a sufficiently shallow angle, they may be reflected directly towards front wall  105 , without passing through central axis  120 . Likewise, when the ultrasonic vibrations strike lens  126  within front wall  105 , they echo back into chamber  103  in a dispersed reflecting pattern towards back wall  104 . As such, some of the ultrasonic vibrations echoing off lens  126  may pass through central axis  120  after striking side wall  113 . Some of the echoing ultrasonic vibrations may travel directly towards back wall  104  after striking side wall  113  without passing through central axis  120 . 
         [0052]    Failing to converge at a single point, or along a single axis, as they travel to front wall  105  and then again as they echo back towards back wall  104 , the ultrasonic vibrations travel back and forth through chamber  103  in a dispersed echoing pattern. Because lens  126  within front wall  105  and lens  122  within back wall  104  contain convex portions  202  and  401 , respectively, free members  127  may travel randomly about the chamber as they move back-and-forth between front wall  105  and back wall  104 . Consequently, the mixing of the fluids induced by the motions of the free members  127  and/or ultrasonic vibrations  119  within chamber  103  may be dispersed throughout chamber  103 . 
         [0053]    It should be appreciated that the configuration of the chamber&#39;s front wall lens need not match the configuration of the chamber&#39;s back wall lens. Furthermore, the lenses within the front and/or back walls of the chamber may comprise any combination of the above mentioned configurations such as, but not limited to, an outer concave portion encircling an inner convex portion. 
         [0054]    As the fluids passing through horn  101  exit channel  110 , they may be atomized into a spray. In the alternative or in combination, the fluids exiting channel  110  may be atomized into a spray by the ultrasonic vibrations emanating from radiation surface  111 . Regardless of whether fluids are atomized as they exit channel  110  and/or by the vibrations emanating from radiation surface  111 , the vibrations emanating from the radiation may direct and/or confine the spray produced. 
         [0055]    The manner in which ultrasonic vibrations emanating from the radiation surface direct the spray produced depends largely upon the conformation of radiation surface  111 .  FIG. 3  illustrates alternative embodiments of the radiation surface.  FIGS. 3   a  and  3   b  depict radiation surfaces  111  comprising a planar face producing a roughly column-like spray pattern. Radiation surface  111  may be tapered such that it is narrower than the width of the horn in at least one dimension oriented orthogonal to the central axis  120  of the horn, as depicted  FIG. 3   b . Ultrasonic vibrations emanating from the radiation surfaces  111  depicted in  FIGS. 3   a  and  3   b  may direct and confine the vast majority of spray  301  ejected from channel  110  to the outer boundaries of the radiation surfaces  111 . Consequently, the majority of spray  301  emitted from channel  110  in  FIGS. 3   a  and  3   b  is initially confined to the geometric boundaries of the respective radiation surfaces. 
         [0056]    The ultrasonic vibrations emitted from the convex portion  303  of the radiation surface  111  depicted in  FIG. 3   c  directs spray  301  radially and longitudinally away from radiation surface  111 . Conversely, the ultrasonic vibrations emanating from the concave portion  304  of the radiation surface  111  depicted in  FIG. 3   e  focuses spray  301  through focus  302 . Maximizing the focusing of spray  301  towards focus  302  may be accomplished by constructing radiation surface  111  such that focus  302  is the focus of an overall parabolic configuration formed in at least two dimensions by concave portion  304 . The radiation surface  111  may also possess a conical portion  305  as depicted in  FIG. 3   d . Ultrasonic vibrations emanating from the conical portion  305  direct the atomized spray  301  inwards. The radiation surface may possess any combination of the above mentioned configurations such as, but not limited to, an outer concave portion encircling an inner convex portion and/or an outer planar portion encompassing an inner conical portion. 
         [0057]    Regardless of the configuration of the radiation surface, adjusting the amplitude of the ultrasonic vibrations traveling down the length of the horn may be useful in focusing the atomized spray produced. The level of confinement obtained by the ultrasonic vibrations emanating from the radiation surface and/or the ultrasonic energy the vibrations carry depends upon the amplitude of the ultrasonic vibrations traveling down horn. As such, increasing the amplitude of the ultrasonic vibrations may narrow the width of the spray pattern produced; thereby focusing the spray produced. For instance, if the fluid spray exceeds the geometric bounds of the radiation surface, i.e. is fanning too wide, increasing the amplitude of the ultrasonic vibrations may narrow the spray. Conversely, if the spray is too narrow, then decreasing the amplitude of the ultrasonic vibrations may widen the spray. If the horn is vibrated in resonance by a piezoelectric transducer attached to its proximal end, increasing the amplitude of the ultrasonic vibrations traveling down the length of the horn may be accomplished by increasing the voltage of the electrical signal driving the transducer. 
         [0058]    The horn may be capable of vibrating in resonance at a frequency of approximately 16 kHz or greater. The ultrasonic vibrations traveling down the horn may have an amplitude of approximately 1 micron or greater. It is preferred that the horn be capable of vibrating in resonance at a frequency between approximately 20 kHz and approximately 200 kHz. It is recommended that the horn be capable of vibrating in resonance at a frequency of approximately 30 kHz. 
         [0059]    The signal driving the ultrasound transducer may be a sinusoidal wave, square wave, triangular wave, trapezoidal wave, or any combination thereof. 
         [0060]    It should be appreciated that elements described with singular articles such as “a”, “an”, and/or “the” and/or otherwise described singularly may be used in plurality. It should also be appreciated that elements described in plurality may be used singularly. 
         [0061]    Although specific embodiments of apparatuses and methods have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, combination, and/or sequence that is calculated to achieve the same purpose may be substituted for the specific embodiments shown. It is to be understood that the above description is intended to be illustrative and not restrictive. Combinations of the above embodiments and other embodiments as well as combinations and sequences of the above methods and other methods of use will be apparent to individuals possessing skill in the art upon review of the present disclosure. 
         [0062]    The scope of the claimed apparatus and methods should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.