Patent Document

RELATED APPLICATIONS  
       [0001]    This application relates to subject matter disclosed co-pending application Ser. No. 09/255,954, filed Feb. 23, 1999, entitled, SKIN ABRASION DEVICE and co-pending application Ser. No. 09/496,394, filed Feb. 2, 2000, entitled, SKIN ABRASION DEVICE, the contents of which are both incorporated by reference herein. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to the removal of surface portions of dead or living tissue, sometimes termed microdermal abrasion or micro-dermabrasion. More particularly, the invention relates to an improved apparatus and process for the abrasion of surface portions of human tissue by the controlled flow of abrasive particles.  
         BACKGROUND OF THE INVENTION  
         [0003]    Conventional microdermal abrasion apparatuses employ a stream of abrasive particles such as sand applied to the surface of the tissue or skin by means of a vacuum pump through an opening in a hand held tool (termed a handpiece) which is sealed against the skin. The handpiece is passed over the area of skin to be abraded so the particle stream can impinge on the skin through an opening in the handpiece. The spent particles and the removed tissue are then collected by vacuum pressure in the handpiece and are delivered to a collection container for later disposal. Suitable filtration is provided to prevent the escape of the abraded tissue and particles into the vacuum pump and the atmosphere.  
           [0004]    Conventional handpieces usually provide a first channel for conducting abrasive particles from a supply container to the area to be treated and a second channel for conducting the spent particles and abraded skin away from the area treated to the collection container.  
           [0005]    A typical prior art microdermal abrasion device is shown in U.S. Pat. No. 5,037,432. The hand-held head disclosed in this patent is a long tubular structure including an inlet passage for the abrasive particles and an outlet passage for removal of the spent particles and abraded skin. A treatment orifice in the form of an off-center hole at a 45° angle to the longitudinal axis of the handpiece is aligned with the abrasive particle inlet passage to permit the abrasive particle to reach the area of skin to be treated.  
           [0006]    The above described handpiece has several drawbacks. Because the treatment orifice is off-axis, the handpiece must be carefully positioned to assure proper contact with the area under treatment, and because it must be held at an angle, is difficult to manipulate over a curved surface such as a human face. As a consequence, the patented handpiece is both uncomfortable and tiring to use.  
           [0007]    Moreover, the patented handpiece has been found to be subject to frequent clogging. This requires the operator to repeatedly stop the treatment to clear the blockage.  
           [0008]    In addition, the handpiece described above includes a disposable tip or bell section which contains the treatment orifice. The tip is press-fitted onto the body of the handpiece and is tightly sealed thereto to prevent accidental escape of abraded skin and loss of vacuum. This makes it hard to remove for replacement. Further, with the treatment orifice positioned off the longitudinal axis, the tip must be carefully aligned with the particle inlet passage. Although an alignment key on the tip and a cooperating keyway on the handpiece body are provided, the need for proper alignment adds to the difficulty of removal and replacement.  
           [0009]    As previously noted, prior art devices typically employ vacuum pumps as the source of operating power. However, the prior art (including the patented device described above) do not provide a convenient way for the suction to be changed by the operator when a weaker or more forceful stream of abrasive particles is desired at particular locations. Similarly, continuously variable control of particle flow rate, i.e., particle volume, has not been provided. Instead, only a single or a few predetermined flow rates are permitted. For example, U.S. Pat. No. 5,954,730, issued to Bemabei, provides a two-position switch operated valve allowing two levels of suction pressure.  
           [0010]    In addition, in some conventional handpieces, the tubes leading from the particle supply container and to the collection container are formed integrally with or press-fitted onto the handpiece. This means that the handpiece must also be discarded when the tubes, which are subject to wear due to the effects of the abrasive particles flowing therein, are replaced. This construction also makes sterilization of the handpiece impractical, and sterility of only the replaceable tip can be assured.  
           [0011]    In other known devices, threaded fittings are provided for connecting the handpiece to the tubes, such as disclosed in U.S. Pat. No. 5,037,432, issued to Molinari. In this device, however, the diameter of the handpiece is small for ease of handling. Therefore, a tool is required to manipulate the threaded connections, which is both inconvenient and time consuming. Also, the small size of the fittings dictates use of fine threads which have proved to be subject to cross-threading.  
           [0012]    Yet a further problem with known prior art relates to the particle supply and waste containers. Typically, the containers are permanent parts of the apparatus so the supply container must be refilled when empty and the waste container must be emptied when full. When either of these operations are performed, clouds of fine abrasive dust are released.  
           [0013]    In the case the supply container, this is an inconvenience in that the dust settles on surrounding surfaces and must be removed. Moreover, care must be taken to avoid abrasion when the surfaces are cleaned.  
           [0014]    In the case of the waste container, however, the problem is more severe as the abraded skin particles are a source of potential biological contamination to which the operator is directly exposed when emptying the waste container. In addition, the dust cloud released when the container is emptied is a source of environmental contamination.  
           [0015]    In one known device disclosed in U.S. Pat. 5,971,999 to Naldoni, a refilled supply container is employed which is then used as the waste container when it is empty. However, these containers are open while they are attached to and removed from the Naldoni machine, so the operator and the environment are still exposed to the clouds of abrasive particles.  
           [0016]    In another known device shown in French Patent 2,712,172 to Rabier, a filter bag inside a non disposable outer container is used for waste collection. The full bag is open when it is removed from the outer container, thus again exposing the operator and the environment to the contaminated waste. Also, during disposal, the operator and the environment will be exposed to any contaminated dust which escapes through the filter bag into the outer container.  
           [0017]    Moreover, with all of the known devices, various non-disposable parts are permanently mounted on the machine. This makes it difficult, if not impossible, to clean these parts thoroughly.  
           [0018]    Yet another problem in the prior art is non-uniform flow and clogging of the abrasive particles in the supply line and the passages of the handpiece. These problems are apparently related in a complex manner to the geometry of the flow passages, and are serious drawbacks in conventional equipment.  
         SUMMARY OF THE INVENTION  
         [0019]    According to the present invention, a novel apparatus and process is provided which alleviates the problems with prior art devices as stated above, and which provides other operational improvements as well.  
           [0020]    A first aspect of the invention is the provision of a novel handpiece having several important features.  
           [0021]    As a first feature, the novel handpiece is comprised of an elongated body portion, a particle supply channel and a waste removal channel extending lengthwise through the body portion, and a removable tip which may be attached to one end of the body portion, A treatment orifice is provided at one end of the tip and is aligned with the longitudinal axis of the handpiece. The particle stream exits the particle supply channel at a point which is radially displaced from the longitudinal axis of the handpiece, but the particle supply channel is so oriented that the stream of abrasive particles is directed substantially toward the center of the treatment orifice. In a preferred embodiment, this is achieved by angularly offsetting the particle supply channel relative to the longitudinal axis of the handpiece.  
           [0022]    A further feature of the novel handpiece is the employment of a coupler having internally tapered body portions which mate with externally tapered plug portions to connect the handpiece to the particle supply and waste removal lines. These couplers can be attached and detached simply by twisting the plug portion relative to the body portion, and their use eliminates the need for permanently secured tubes, couplers requiring tools for connection and disconnection or employment of fittings large enough to permit finger manipulation.  
           [0023]    According to another feature of the handpiece of the present invention, the diameter of the waste removal channel in the handpiece is substantially larger than that of the particle supply.  
           [0024]    According to a second aspect of the invention, a novel particle supply container is provided which controllably aerates the abrasive particles before delivery to the handpiece. In one such supply container, a mixing tube, open at the top, is positioned in the container with its top opening above the particle fill level. The bottom of the mixing tube is connected to a tube which feeds the handpiece particle supply channel. Air is introduced to the container through an inlet opening, and is drawn into the mixing tube by the suction in the system. An opening in the side of the mixing tube near the bottom admits particles under gravity feed, and the particles are mixed with the air stream before exiting the supply container into the particle feed tube. Fine control of the air-particle ratio is provided by a valve which permits additional air to enter the particle feed line just outside the container.  
           [0025]    According to another container design, the top of the mixing tube extends through an opening in the top of the container. This eliminates the need for a separate air inlet. Pressure equalization above the level of the particles in the supply container is provided by an outlet hole near the top of the mixing tube.  
           [0026]    According to a further container design, a separate air inlet tube is provided which enters the container at the bottom and delivers air through a top opening to the space above the stored particles. Air enters the top of the mixing tube and particles are gravity fed through a hole near the bottom as in the previously described designs.  
           [0027]    In other designs, separate particle supply tubes are connected to the mixing tube, and in yet further variations, mixing chambers are provided at the bottom of the container in which the aeration process takes place.  
           [0028]    Employment of controlled aeration not only alleviates clogging of the particle flow passages, but also improves the uniformity of particle flow, and permits continuous variable flow rate (particle volume) adjustment.  
           [0029]    According to a third aspect of the invention, the particle supply container is designed to be pre-filled by a supplier, installed in a substantially sealed condition, and disposed of in a substantially sealed condition when it is empty. The waste receptacle which receives the spent particles and the abraded skin includes an internal filter also designed for disposal in a substantially sealed condition. This eliminates the need for the operator to refill the supply container and empty and clean the waste receptacle, and even of greater importance, prevents exposure of the operator and the environment to the abrasive particles and the removed skin.  
           [0030]    As a fourth aspect of the present invention, there is provided an improved design for a microdermal abrasion apparatus in which an aerated stream of abrasive particles is transported from a pre-filled and disposable supply container having the various features and advantages described above, delivered through a supply tube to an inlet channel in a handpiece, and is delivered from the inlet channel to an axially positioned treatment orifice in a disposable tip at the end of the handpiece. The inlet channel in the handpiece is designed so that the stream of abrasive particles is directed substantially toward the center of the treatment orifice.  
           [0031]    Air is evacuated from the tip by a vacuum source connected to a waste removal channel which extends through the handpiece. The spent abrasive particles and the abraded skin, are withdrawn by the suction and delivered through a waste removal line to a combined waste filter and disposal container (referred to below as a “disposable waste filter” or “waste filter”).  
           [0032]    The apparatus as described in this aspect of the invention avoids exposure to both clean and contaminated abrasive particles, functions substantially without clogging, provides convenient adjustment of the particle volume and application force, and allows comfortable and convenient use by the operator.  
           [0033]    As still another aspect of the present invention there is provided an improved method for microdermal abrasion in which an aerated stream of abrasive particles is transported from a pre-filled and disposable supply container having the various features and advantages described above, delivered through a supply tube to an inlet channel in a handpiece, and is delivered from the inlet channel to an axially positioned treatment orifice in a disposable tip at the end of the handpiece. The incoming stream of abrasive particles is directed substantially toward the center of the treatment orifice.  
           [0034]    Air is evacuated from the tip by a vacuum source connected to a waste removal channel which extends through the handpiece. The tip is placed against a surface of the skin to be abraded with the opening in the tip sealed against the skin. The spent abrasive particles and the abraded skin are withdrawn by the suction and delivered through a waste removal line to a disposable waste filter.  
           [0035]    Other features of the invention, and advantages over the prior art will become apparent from consideration of the following detailed description in conjunction with the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0036]    [0036]FIG. 1 is a schematic diagram of a novel microdermal abrasion system as described in the present invention.  
         [0037]    [0037]FIG. 2 is a perspective view of a novel handpiece as described in the present invention.  
         [0038]    [0038]FIG. 3 is an exploded longitudinal sectional view of the handpiece shown in FIG. 2.  
         [0039]    [0039]FIG. 4 is a fragmentary sectional view illustrating an alternative construction of the particle supply channel of the handpiece illustrated in FIG. 3.  
         [0040]    [0040]FIG. 5 is a side elevation of a tapered handpiece coupler as described in the invention.  
         [0041]    [0041]FIG. 6 is vertical sectional view of a disposable waste filter as described in the invention.  
         [0042]    [0042]FIG. 7 is a cross-sectional view taken along line  7 - 7  in FIG. 6.  
         [0043]    [0043]FIG. 8 is a side elevation of a first embodiment of novel pre-filled disposable particle supply container as described in the invention.  
         [0044]    [0044]FIG. 9 is a top view of the particle supply container illustrated in FIG. 8.  
         [0045]    [0045]FIG. 10 is an enlarged view of a portion of the aeration tube of the supply container of FIG. 8 showing the particle inlet opening.  
         [0046]    [0046]FIG. 11 is a side elevation of a second embodiment of the novel particle supply container as described in the invention.  
         [0047]    [0047]FIG. 12 is a side elevation of a third embodiment of the novel particle supply container as described in the invention.  
         [0048]    [0048]FIG. 13 is a fragmentary schematic side view of a modified aeration tube as described in the invention.  
         [0049]    [0049]FIG. 14 is a cross-sectional view taken along line  14 - 14  in FIG. 13.  
         [0050]    [0050]FIG. 15 is a fragmentary schematic side view of a fourth embodiment of the novel particle supply container as described in the invention.  
         [0051]    [0051]FIG. 16 is a cross-sectional view taken along section line  16 - 16  in FIG. 15.  
         [0052]    [0052]FIG. 17 is a cross-sectional view taken along section line  17 - 17  in FIG. 15.  
         [0053]    [0053]FIG. 18 is a fragmentary side view of an aeration manifold as described in the invention.  
         [0054]    [0054]FIG. 19 is a cross-sectional view taken along section line  19 - 19  in FIG. 18.  
         [0055]    [0055]FIG. 20 is a schematic side elevation of an alternative construction of an aeration manifold as described in the invention.  
         [0056]    [0056]FIG. 21 is a cross-sectional view taken along section line  21 - 21 in FIG. 20.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0057]    Referring to the drawings, in which like reference numerals refer to like elements, there is shown in FIG. 1 a microdermal abrasion apparatus generally denoted at  10 , comprised of an abrasive supply container  12 , a handpiece  14 , a disposable waste filter  16 , an air line filter  20  and a vacuum pump  22 . Waste filter  16  is comprised of a primary filter element  17 , and a secondary filter element  18 , both housed in a sealed outer container  19 .  
         [0058]    The particle supply path from container  12  to handpiece  14  is comprised of an outlet tube  24  connected to container  12  by an outlet coupler  26 , a Tee-connector  28  and a particle supply line  30 , the latter connected to handpiece  14  by an inlet coupler  32 . The leg  34  of Tee-connector  28  is connected to an air supply valve  36 , as described in more detail below.  
         [0059]    A waste disposal line  38  connects handpiece  14  to waste filter  16 . An outlet coupler  40  at one end of waste disposal line  38  connects to handpiece  14 . The other end of waste disposal line  38  connects to an inlet line  44  on waste filter  16  by means of a suitable fitting  42 .  
         [0060]    Vacuum pump  22  provides the suction for delivery of abrasive particles to handpiece  14  and for waste removal. Waste filter  16  is connected to vacuum pump  22  in any convenient or desired manner, e.g., by a first air outlet line  46 , air line filter  20  and a second air outlet line  48 . Air outlet line  46  is connected to an outlet tube  50  extending from waste filter  16  by a suitable fitting  52 . Vacuum pressure may be controlled by a continuously variable air inlet valve  54 . A pressure gauge  56  may also be provided to monitor the suction at the input to pump  22 . The exhaust air from pump  22  may be exhausted to the atmosphere through a final filter/muffler  58 .  
         [0061]    As illustrated in FIG. 1- 3 , handpiece  14  is comprised of a cylindrical body  70  and a threadedly attached disposable tip  72 . An inlet channel  74  extending through body portion  70  provides an inlet path for abrasive particles into tip  72 , and a waste removal channel  76  extending through body portion  70  with an inlet opening  76   a  in face  76   b  of body  70  provides a waste disposal path for spent particles and abraded skin out of tip  72 .  
         [0062]    Removable tip  72  is formed of polycarbonate or other suitable plastic material and is comprised of a hollow cylindrical portion  78  and a curved end portion  80  which may be hemispheric, parabolic or the like. An axially located treatment orifice  82  at the end of tip  72  provides access by the stream of abrasive particles to the portion of the skin to be abraded. The diameter of orifice  82  is not critical, but good results are achieved with a diameter in the range of 0.25 to 0.375 in. (0.635-0.953 cm.)  
         [0063]    Handpiece body  70  may be formed Teflon® or other suitable plastic and may be molded or machined to the required shape. Alternatively, handpiece body  70  may be comprised of stainless steel. The outside dimensions of handpiece  14  are not critical, but good results in terms of operator comfort and convenience are achieved with a handpiece having an overall length of less than 3 inches (7.62 cm.), e.g., 2.25 inches (5.715 cm.), and a diameter of less than 1.0 inch (2.54 cm.), e.g., 0.875 inch (2.22.25).  
         [0064]    The diameters of channels  74  and  76  are also not critical, but must be sufficiently large to provide adequate particle flow with a vacuum pump  22  of reasonable capacity and power. It has also been found that the diameter of waste removal channel  76  should be larger than particle supply channel  74 . This helps promote rapid removal of spent abrasive particles and abraded skin, especially if the vacuum inside tip  72  is broken due to loss of contact of treatment orifice  82  with the skin surface. At the same time, if channels  74  and  76  are too large, the diameter of handpiece  14  must be increased, with consequent loss of maneuverability and operator comfort. Given the foregoing considerations, it has been found that good results may be achieved if channels  33  and  34  are respectively 0.11 in. (2.794 mm.) and 0.80 in. (20.32 mm.) in diameter.  
         [0065]    Handpiece body  70  is threadedly connected to tip  72  by external threads  84  that engage with complementary internal threads  86  on cylindrical portion  78  of tip  72 . An O-ring seal  88  is provided at the base of threaded portion  84  and engages with an unthreaded skirt portion  90  at the end of tip  72 .  
         [0066]    As previously noted, treatment orifice  82  is preferably located axially at the end of tip  72 . It has been found, however, that tissue removal is most effectively performed if the stream of abrasive particles is aimed directly at treatment orifice  82 . Since channels  74  and  76  are laterally offset from the central axis of handpiece body  70 , to direct the incoming particle stream into orifice  82 , inlet channel  74  is oriented at a small angular offset from the longitudinal axis of handpiece body  70 . For a handpiece and tip having the dimensions indicated above, it has been found that the offset angle θ, as illustrated in FIG. 3 is advantageously in the range of 3-4 degrees.  
         [0067]    Alternatively, as illustrated in FIG. 4, instead of angling the entire length of channel  74 , the upstream end  92  is oriented parallel to waste removal channel  76 , and only the downstream discharge end  94  of channel  74  is angled.  
         [0068]    It will, of course, be understood that the value of offset angle θ will depend on the particular dimensions of handpiece  14  and tip  72 , the important consideration being that the particle stream impinge, as nearly as possible, in the center of treatment orifice  82 .  
         [0069]    In either the configuration of FIG. 3 or FIG. 4, an abrasion-resistant nozzle insert  96 , fitted in a counter-bore  98  at the outlet end of supply channel  74 , may be provided, as illustrated in FIG. 3. The abrasive particle stream thus exits toward treatment orifice  82  through opening  96   a.    
         [0070]    Microdermal abrasion unit  10  is preferably constructed with its major parts as an integrated unit. Thus, supply container  12 , waste filter  16 , tertiary in-line filter  50 , vacuum pump  22 , and the various ancillary parts are all preferably mounted in a single cabinet (not shown). Waste filter  16  and supply container  12  are preferably positioned for easy access and to facilitate removal as explained below.  
         [0071]    Referring to FIGS. 6 and 7, waste filter  16  is comprised of a cylindrical outer container  100  having a tubular body  101  permanently attached to top and bottom end caps(FIGS. 102 and 104). These may be comprised of metal, plastic or heavy cardboard tube. Within outer container  100  is primary filter  17 . This may be cylindrical in form and comprised of a pleated inner portion  108  over-wrapped with a flat filter paper portion  110 . Alternatively, filter element  108  may be formed of a single layer, having either a pleated structure or a flat tubular structure. Filter element  108  is selected to ensure trapping of the  120  micron sized abrasive particles and the abraded tissue.  
         [0072]    Filter element  108  defines a boundary between a central volume  112  enclosed thereby and an exterior generally annular shaped sealed volume  114  between the filter element and the interior of outer container  100 .  
         [0073]    Filter element  17  is fixed in place by cementing it to the top and bottom end caps  102  and  104 , using a potting compound or the like, before outer container  100  is assembled. Top end cap  102  has openings  116  and  118  which receive air outlet tube  50  and waste inlet tube  44  sealingly connected therein. Tubes  50  and  44  may be flexible plastic tubes with O.D.&#39;s of ⅜ and ¼ inch respectively.  
         [0074]    Tube  50  extends through opening  116 , and is connected at its end to secondary filter  18  which helps assure that there will be no venting of the waste material accumulated within waste filter  16 , even if primary filter  17  ruptures for some reason. The illustrated construction also permits disposal of secondary filter  18  without risk of exposure to the waste material.  
         [0075]    Since waste filter  16  is a unitary structure, it is conveniently removable, and disposable in one piece by disconnection of tubes  50  and  44  respectively from in-line filter  20  and output channel  76  in handpiece  14 . Tubes  44  and  50  are advantageously long enough to be connected together as by a fitting  42  which fits into the end of tube  50  to completely seal the container for disposal.  
         [0076]    It will be understood by those skilled in the art, however, that other forms of waste filters which permit disposal without exposure to the accumulated waste material may also be employed within the scope of this invention.  
         [0077]    Referring again to FIG. 3, a small control opening  120  is provided in tip  72 . This can be closed by the operator&#39;s finger to increase the vacuum and thereby produce a more forceful stream of abrasive particles against the skin being abraded when required without adjustment of valve  54  (see FIG. 1).  
         [0078]    As will be appreciated, the same result can be obtained by placing an opening in handpiece body  70  (not shown) in communication with the interior of either inlet channel  74  or waste removal channel  76 .  
         [0079]    Referring to FIGS. 2 and 5, the upstream ends of channels  74  and  76  are internally tapered at  122  and  124  to receive tapered end portions of couplers  32  and  40 . Coupler  32 , illustrated in FIG. 5, is comprised of a pin  126  having a tapered end portion  128  adapted to fit into tapered end  122  of channel  74 , a flange  130  and a cylindrical rear body portion  132  taped at its end  134 , and adapted to fit into particle supply tube  30 . Flange  130  provides a shoulder against which the end of tube  30  rests when assembled. (As will be understood, tube  30  may be heated before insertion of pin  126  so that the tube contracts around rear portion  132 , thereby ensuring a tight fit. Coupler  40  is similarly constructed.  
         [0080]    As will be understood by those skilled in the art, such a tapered connection (known as a Morse taper) provides a reliable connection which can be easily made and released even under substantial internal pressure simply by twisting plug  126 . The periphery of flange  130  may be knurled at  136  to facilitate grasping for this purpose. The resulting connections are secure, but may easily be released by twisting the plug with two fingers. No tools are needed, and enlargement of the diameter of handpiece  14  to allow manipulation of the couplings is unnecessary.  
         [0081]    It should also be understood that tapered fittings as described above may be used for other parts herein which must be connected and disconnected, such as the connections between waste filter  16  and tubes  38  and  46 , the connection between vacuum pump  22  and tube  48 , etc.  
         [0082]    Two factors which have been found to be important in achieving satisfactory operation are the rate and uniformity of particle flow past treatment orifice  82  in handpiece  14 . As will be appreciated, maximum particle flow rate depends in part on the capacity of vacuum pump  22 . It has been found that effective treatment can be achieved in a practical configuration using a ¼ to ½ horsepower vacuum pump providing 90-98 KPA  
         [0083]    Uniformity of particle flow has been found to be related to the geometry of the structure of the particle flow path. This can produce rather complex effects, which in the extreme, can cause serious and frequent clogging of particle flow paths. It has been found, however, that such effects can be minimized by controlled mixing of air and particles before the particles are transported to handpiece  14 . This may be done quite conveniently at supply container  12  using any of the embodiments described below. As a result, particle flow may be made substantially uniform, and clogging largely eliminated.  
         [0084]    FIGS.  8 - 10  illustrate a preferred embodiment for particle supply container  12 . As shown, container  12  is comprised of an outer receptacle  170  having a top  168  and a bottom opening  171  sealed by a suitable closure such as an end cap  172 , a first air inlet  179  and an aeration device generally denoted at  176 .  
         [0085]    In the illustrated embodiment, aeration device  176  is comprised of a mixing chamber in the form of a tube  177 , a second air inlet  178  and a particle inlet device  180 . Tube  177  extends vertically to a point adjacent to the top of receptacle  170 . A second air inlet  178  at the top of tube  177  permits inflow of air for mixing with the abrasive particles as described below. The bottom of tube  177  communicates through an opening  174  in end cap  172  with outlet coupler  26 , which, in turn, is connected by outlet tube  24  and Tee-connector  28  to particle supplied tube  30  (see FIG. 1).  
         [0086]    Referring again to FIGS.  8 - 10 , first air inlet  179  is provided in the top of receptacle  170  to vent the air space above the particle fill level  186  to the atmosphere. An air filter  182  is secured over air inlet  179 , e.g., by gluing at its periphery  184  to receptacle top  168 .  
         [0087]    In use, a supply container  12  is pre-filled by a supplier with abrasive material leaving an air space  186  below the top  178  of mixing tube  176 . As will be understood, this permits air to be drawn into the tube by the suction created by vacuum pump  22  (see FIG. 1). The prefilled container is installed by removing a shipping cap (not shown) from the end of tube  176  and fitting  26  is attached to the tube  24 .  
         [0088]    Still referring to FIGS. 8 and 10, particle inlet opening  180  near the bottom of mixing tube  176  permits abrasive particles to enter the tube under the force of gravity and to create an air-particle mixture which is then transported through supply tube  30  to hand-piece  14 . By aerating the particles in this manner, clumping due to accumulation of moisture is prevented without the need for heaters to dry the particles or vibrations, as are sometimes employed.  
         [0089]    The dimensions of air intake opening  179  and particle inlet opening  180  in mixing tube  176  are selected to provide the desired degree of aeration. Good results are achieved with an air intake opening  179  having an internal diameter in the range of 0.1 to 0.175 in. (0.445 cm.), and preferably 0.125 in (0.3175 cm.) an outside diameter for tube  176  of 0.25 in. (0.635 cm.) and a particle inlet opening having a diameter in the range of 0.063 to 0.090 in. (1.006-2.286 mm.), and preferably 0.080 in. (2.032 mm.).  
         [0090]    Further adjustment of the aeration maybe achieved by use of valve  36  connected to leg  34  of Tee-connector  28 . By opening valve  36 , more air is introduced to supply tube  30 , thus reducing the quantity of abrasive particles. This allows continuous and infinite adjustment of the particle flow rate.  
         [0091]    In a practical application, the capacity of container  12  maybe 1-5 pounds (0.4542-2.268 kg.). Particle size is not critical, but it has been found that good results are achieved using irregularly shaped aluminum oxide particles having a maximum dimension less than about 120 microns and with sharp irregular edges.  
         [0092]    When the container is empty, it is removed and replaced by a new prefilled container. The shipping cap is reapplied to the end of tube  176  and the empty container is then discarded.  
         [0093]    FIGS.  11 - 21  illustrate several alternative embodiments for supply container  12 . The embodiment shown in FIG. 11 differs from the embodiment of FIGS.  8 - 10  in that mixing tube  176  extends through a fitting  188  in the upper wall  189  of receptacle  170 . Air enters tube  176  through an opening  191 . A protective cap  190  is provided over opening  191 . No separate air inlet such as  179  (see FIG. 8) is needed, but an air outlet hole  192  is provided near the top of tube  176  to vent air space  186  to the atmosphere. As will be understood, this is necessary to permit the particles to be drawn into particle supply opening  180  in tube  176 .  
         [0094]    The embodiment shown in FIG. 12 differs from that of FIG. 11 in that a separate air supply tube  194  is provided. Tube  194  is mounted in a fitting  198  in receptacle end closure  172 , extends upwardly within receptacle  170  to a point above particle fill level  186  and terminates in an opening  196 . Air enters tube  176  at its open top  178  and mixes with particles entering at inlet opening  180 . Tube  176  terminates at a fitting  200  in closure  172 , where it may be connected directly to particle supply tube  22  (see FIG. 1). Tee-coupler  28  and air valve  36  shown in FIG. 1 are not used. Instead, an in-line valve  202  in air intake tube  194  is provided to adjust air flow.  
         [0095]    The embodiment of FIGS. 13 and 14 employs a separate particle inlet tube  204  which extends through an opening  180  in a mixing tube  176 . Inlet tube  180  is positioned at an angle, e.g., 45°, so particles entering at upper opening  206  are gravity fed through lower opening  208  and are mixed with the air stream in outlet tube  176 .  
         [0096]    In the embodiment of FIGS.  15 - 17 , the mixing chamber and the outlet device are combined. Air is provided from above, as in the previously described embodiments, through a vertically extending tube  210 . Tube  210  is connected at its bottom end to a funnel  212  which terminates in a spout  214 , the latter being connected to outlet tube  24  (see FIG. 1).  
         [0097]    Abrasive particles are gravity-fed into spout  214  by a particle feed device generally denoted at  216 , which is comprised of a circular trough  218  that surrounds tube  210 . Trough  218  is open at the top and is comprised of a side wall  219  and an annular bottom plate  220 . Outlet tubes  222  connected to openings  224  in trough bottom  220  feed into spout  214  through openings  226 .  
         [0098]    As will be understood, the constructions shown in FIGS.  13 - 14  and FIGS.  15 - 17  may be used instead of the tubular mixing chambers and particle inlet devices in any of the embodiments shown in FIGS.  8 - 12 .  
         [0099]    In the embodiment illustrated in FIGS. 18 and 19, a tubular mixing chamber  230  is attached to the bottom  232  of receptacle  170 . Spaced holes  234  in tube  230  communicate with aligned holes  236  in receptacle bottom  232  to permit a particle inlet. Alternatively, holes  234  may communicate with the interior of receptacle  170  through a slot in receptacle bottom  232  (not shown). Air is supplied through an air inlet  236  at one end of tube  230  and mixes with particles which are gravity fed through holes  234 . The aerated mixture exits through an outlet device  238 , which may be connected directly particle supply line  30 . The air supply at inlet  236  and accordingly particle volume, may be controlled by an air valve (not shown).  
         [0100]    A variant of the embodiment of FIGS.  18 - 19  is shown in FIGS. 20 and 21. Here, a cylindrical mixing chamber  240  is formed at the bottom of receptacle  170  by a horizontal dividing wall  242 , including a plurality of perforations  246  by which the particles are gravity fed into mixing chamber  240 . As in the embodiment of FIGS.  18 - 19 , air is supplied at an inlet  248  through a valve (not shown) and the aerated mixture exits through an outlet device  250 .  
         [0101]    In summary, the present invention provides improvements in the art of microdermal abrasion including continuous variability of the particle flow rate and substantial elimination of shutdown due to clogging of the particle flow tubes, as well as improved uniformity of particle flow.  
         [0102]    In addition, the present invention provides a nozzle and input channel which direct the flow of abrasive particles toward substantially the center of the opening in the tip, thereby improving the performance of the dermabrasion process.  
         [0103]    Also, the Morse taper couplings employed as described in the present invention, particularly for connecting the particle supply and waste disposal lines to the handpiece, permit convenient connection and disconnection without tools, and allow the handpiece to be made small enough for convenient and comfortable use.  
         [0104]    Moreover, the design of the supply container and waste filter permit disposal without risk of exposure to either clean or contaminated materials.  
         [0105]    Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. Thus, other designs for the handpiece, the disposable supply container an the waste filter are possible. Similarly, the supply container need not be disposable. Instead it may be constructed in a manner permitting it to be refilled upon return to the supplier.  
         [0106]    It is intended, therefore, that the scope of invention be limited not by the specific disclosure herein, but only by the appended claims.

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