Abstract:
A combination of ultrasonic waves causing microcavitation bubbles to form between the surface of a contact lens and an attached contaminant layer formed by microbes thereon initiates separation. However, a vigorous convective flow takes advantage of any localized breaking and separating of the contaminant layer and immediately imposes a hydrodynamic drag force on the pieces of the contaminant layer that may be separated, thus leading to greater separation, pealing, and tearing of the contaminant layer away from the surface. Thus, the combination has proven much more effective than either feature alone. 
     The present invention may be embodied in other specific forms without departing from its fundamental functions or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. All changes which come within the meaning and range of equivalency of the illustrative embodiments are to be embraced within their scope.

Description:
RELATED APPLICATIONS 
       [0001]    This application: claims the benefit of co-pending U.S. Provisional Patent Application Ser. No. 61/576,271, filed on Dec. 15, 2012; which is hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    1. The Field of the Invention 
         [0003]    This invention pertains to cleaning systems and, more particularly, to novel systems and methods for cleaning contact lenses. 
         [0004]    2. The Background Art 
         [0005]    Spectacles or eyeglasses have given way in many instances to contact lenses. The original hard contact lenses of decades past have largely given way to soft contact lenses. These soft contact lenses provide not only softer, more flexible plastics but also plastics that are semi-permeable. These semi-permeable or gas-permeable lenses permit oxygen to pass through the matrix of the lens material and thus oxygenate the surface of the eye on which the contact rests during use. 
         [0006]    Nevertheless, soft contact lenses or gas-permeable contact lenses are not without their own problems limitations. For example, users are typically advised on a cleaning and wearing protocol for the lenses. Severe injury or blindness can occur if the protocol is not followed. Sometimes, lenses may be torn by too vigorous handling. 
         [0007]    Regardless, lenses tend to build up a film of contaminants. Contaminants are commonly deposited on surfaces of the lens and eventually develop growth into the interstices or openings within the plastic matrix of the lens itself. These contaminants are supposedly removed by cleaning. 
         [0008]    However, it has been found that even the best mechanical and chemical cleaning techniques can typically remove particulate matter that presents unevenness and the like. However, these are often insufficient to completely clean up the well-developed, smoother layer of contaminants. Current washers, liquids, chemicals, and the like render the lenses caustic and unwearable. That is, if harsh chemicals are used, then it is imperative yet difficult to return the pH level of the lens to a suitable level in order to make them comfortable and not damaging to the eyes of the user. 
         [0009]    It would be an improvement in the art to discover and implement a method for more effective cleaning of contact lenses that is rapid, safe, and simple. 
       SUMMARY OF THE INVENTION 
       [0010]    In view of the foregoing, in accordance with the invention as embodied and broadly described herein, an apparatus and method implementing both ultrasonic cavitation and microcavitation between the lens and the contaminant layer. In addition, a lateral shear flow by a convective current assists in the mechanical removal of the contaminant layer. 
         [0011]    Whereas abrasion has been shown to be damaging and ineffective, an initial imposition of ultrasonic waves results in microcavitation in the contaminant layer, and particularly between the contact lens and the contaminant layer where differences in material properties tend to be emphasized by the ultrasonic waves. Moreover, by imposing a lateral shear by convective currents passing over the surface of the contact lens, any fracturing or rupture of the contaminant layer is immediately amplified by the high shear in the boundary layer of the passing, convective fluid flow. In this way, the contaminant layer is separated from the surface of the contact lens and mechanically removed. 
         [0012]    In one implementation, a method for cleaning contact lenses may provide a basket for containment, a lens having a contaminant layer developing on it, and a containment vessel or well. Placing the lens in the basket and the basket in a container containing a liquid is followed by creating ultrasonic waves in the liquid by operation of an ultrasonic transducer moving a wall of the container, typically its floor. 
         [0013]    This creates micro cavitation tending to cause bubbles between the contaminant layer and the lens. Passing a convective flow across a surface of the lens causes fluid drag, lifting the contaminant layer away, peeling it back, and tearing it off the lens to which it has attached. The flow carries the torn pieces of the contaminant film from the lens. The convective flow has been found best if operating in a turbulent regime. However, more important is stripping away and thinning the boundary layer sufficiently to expose the contaminant layer to the fluid drag, which gently but firmly lifts, peels, and tears it away. This is more difficult with laminar flow. 
         [0014]    The ultrasonic waves are selected to be effective to create micro-cavitation lifting the contaminant layer away from the lens. Normally, this might still allow a re-laying of the layer, and re-attachment. However, the convective flow is effective to create dynamic head pressure under the layer at points of disruption and hydrodynamic drag against any portion of the contaminant layer separated by the ultrasonic waves from the lens. The hydrodynamic drag is sufficient to engage the tensile strength of the contaminant layer, causing separated portions to peel neighboring regions away from the surface of the lens. 
         [0015]    Typically, the contaminant layer is bonded to the lens by mechanical extension of the contaminant layer into the matrix of a polymer forming the lens. The ultrasonic waves are introduced at a frequency and power effective to create bubbles forcing the contaminant layer from the lens at localized places. The bubbles create tensile stresses in the contaminant layer, lifting, and sometimes rendering or rupturing the layer. Separating the first portion of the contaminant layer from the lens by the hydrodynamic drag creates tensile stresses in the contaminant layer to support continued peeling and eventual tearing. 
         [0016]    An apparatus for cleaning contact lenses may include a well containing a liquid, with a basket submerged in the liquid and holding an article such as a lens, having a surface to be cleaned of protein, biofilms, or other contaminants. A contaminant layer is typically disposed as a contiguous film on the surface and bonded thereto by a mechanical engagement, as well as other adhesive forces. 
         [0017]    A transducer creates ultrasonic waves in the liquid impinging on the surface. A convector creates convection currents passing along the surface. The transducer provides the power and motion to break loose the bonding of the contaminant layer by cavitating (vaporizing) the liquid proximate the surface in response to a pressure wave due to movement at a comparatively high speed. The convector, first lifts, then begins to peel, and eventually tears the contaminant layer from the surface by applying fluid drag to any portion of the contaminant layer extending out of the boundary layer (typically a comparatively thin boundary layer in accordance with high Reynolds&#39; number flows in the turbulent regime) into the convection current. 
         [0018]    The frequency of the waves is ultrasonic, and has been found to serve best in a range of from about 30 to about 120 kilohertz. A Piezoelectric transducer was used in experiments to create the waves. The convector was a motor driving an impeller (propeller, fan, etc.) The liquid was water, treated with a combination of a cleaning agent such as a surfactant, a bactericide, and a salt in the best or most effective configurations. 
         [0019]    It appears that a contact lens is formed of a polymer having strands defining interstices therebetween; and the contaminant layer extends into the interstices. Thus, in addition to any adhesive properties of the contaminant biofilm, it appears to mechanically grow into those interstices, maintaining a mechanical adherence as well. Other cleaning methods and apparatus have not been successful at stripping away such contaminant films. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The foregoing and other objects and features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which: 
           [0021]      FIG. 1  is a frontal cross sectional view of a cleaning apparatus in accordance with the invention; 
           [0022]      FIG. 2  is a frontal cross sectional view of the core of the apparatus of  FIG. 1  removed from the outer housing in order to illustrate certain operational components therein; 
           [0023]      FIG. 3  is an upper perspective view of the apparatus of  FIG. 1 , having the core of  FIG. 2  removed and illustrating the central well that receives the core; 
           [0024]      FIG. 4  is a perspective view of the apparatus of  FIG. 1 , having the core and its lid to which it is placed in the housing; 
           [0025]      FIG. 5  is a side elevation view from the right side of the apparatus of  FIG. 1 ; 
           [0026]      FIG. 6  is a cross sectional view of the arrangement of a contact lens attached to a cornea of an eye and illustrating the location of a contaminant layer attached to the contact lens; 
           [0027]      FIG. 7  is a schematic diagram illustrating the operable components and effects of an apparatus and method in accordance with the invention for cleaning contact lenses; 
           [0028]      FIG. 8  is a schematic diagram of the activities at the interface between the contaminant layer and the contact lens during the cleaning process; 
           [0029]      FIG. 9  is a magnified view of a contaminant layer of a contact lens during the cleaning process in accordance with the invention; 
           [0030]      FIG. 10  is an image illustrating the polymer chains and the interstices therebetween in a layer of a polymer as viewed in a scanning electron micrograph of such a layer, thereby illustrating the interstitial spaces in which microbiological organisms may bind themselves; 
           [0031]      FIG. 11  is a sequence of activity during one embodiment of a cleaning process; 
           [0032]      FIG. 11A  is a schematic diagram illustrating the condition of a contact lens surface covered by a contaminant layer; 
           [0033]      FIG. 11B  is a schematic diagram illustrating microcavitation tending to cause localized separation of the contaminant layer of the contact lens; 
           [0034]      FIG. 11C  is a schematic diagram illustrating rupture of the contaminant layer; and 
           [0035]      FIG. 11D  is a schematic diagram illustrating the shearing force of the boundary layer of a convective flow tearing away the contaminant layer from the surface of a contact lens. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]    It will be readily understood that the components of the present invention, as generally described and illustrated in the drawings herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in the drawings, is not intended to limit the scope of the invention, but is merely representative of various embodiments of the invention. The illustrated embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. 
         [0037]    Referring to  FIG. 1 , an apparatus  10  or system  10  in accordance with the invention may include a housing  12 . Inside the housing  12  is contained a convection drive assembly  14  or assembly  14  responsible to provide convective shear forces across a surface. In the illustrated embodiment, the assembly  14  or drive  14  is contained within a well  16  within the housing  12 . 
         [0038]    At the bottom of the well  16  is placed a transducer  18 . Typically, the transducer  18  may be a piezoelectric transducer changing dimension with each change in voltage. 
         [0039]    In certain embodiments, the well  16  may be the entire housing  12 . Nevertheless, in other embodiments it may be useful to leave space between the outer wall of the well  16  and the housing  12 . For example, in order to insulate against sound transmission, thermal variations, or the like, including aesthetic reasons or benefits, the well  16  may or may not be coincident with the outer wall of the housing  12 . 
         [0040]    In the illustrated embodiment, a transducer  18  is responsible for generating ultrasonic waves within the liquid inside the well  16 . The ultrasonic waves result in localized cavitation and microcavitation on the surface of the contact lens within the well  16 . 
         [0041]    The transducer  18  and other electronic and electrical components of system  10  in accordance with the invention may be housed within a chamber  20 , isolating electrical and electronic components from the liquids, such as water, that may be spilled to the electronics or to the transducer  18  from the well  16 . 
         [0042]    The outer wall  22  of the housing  12  may be spaced from the well  16  in order to provide isolation as described hereinabove. Nevertheless, in certain embodiments, aesthetically pleasing shapes may be designed into the housing  12 , thus requiring some difference between the location and size of the wall  22  and that of the well  16 . 
         [0043]    In the illustrated embodiment, the floor  24  of the housing  12  may support various other structures, including the well  16 . For example, the housing  12  may include a cavity  26  containing a surrounding ambient air, another liquid, insulation against thermal transmission, insulation against sound transmission, or the like. 
         [0044]    In certain embodiments, a cover  28  may form a structural alignment device  28  in order to position and maintain the well  16  within the housing  12 . The cover  28  operates as a mechanical restraint holding the well  16  in place. It may have a clearance, an elastomeric gasket for vibration isolation or the like with respect to the well  16 . 
         [0045]    Referring to  FIGS. 1-5  in general, while continuing to refer to  FIG. 1  specifically, the lid  30  may form a backbone  30  for the convection drive assembly  14 . Similarly, the lid  30  operates to form the closure  30  of the housing  12  over the well  16 . In the illustrated embodiment, the lid  30  may be hinged or otherwise removable from the remainder of the housing  12  in order to remove the convection drive assembly  14  for use, for loading, or the like. 
         [0046]    Opposite the lid  30 , a mount  32  for the well  16  may be formed contiguously with the floor  24  of the housing  12 . The mount  32  may operate to register the well  16  and to constrain the well  16  opposite the cover  28 . Thus, the well  16  may be removable. In other embodiments, the well  16  may actually be molded integrally with the housing  12 . However, in the illustrated embodiment, it has been found effective to render the well  16  removable. Thus, in operation, the well  16  may be captured or restrained between the mount  32  therebelow and the cover  28  above. Alternatively, the well  16  may be isolated from the mount  32  to enhance vibration. In yet another embodiment the transducer may be mounted to the well  16  and provide its exclusive support with respect to the floor  24 . 
         [0047]    A cavity  34  in the housing  12  and within the envelope of the mount  32  may contain the transducer  18 . It is important to keep the transducer  18  in intimate mechanical contact with the well  16 . Accordingly, in certain embodiments, the transducer  18  may actually be bonded to the well  16 , in order to transmit mechanical vibrations directly to the well  16 , and any contained fluid therein. Thus, some cavity  34  or relief  34  will typically be required in order to provide the transducer  18  the required space to operate. Moreover, the cavity  34  may typically separate the transducer  18  from an outer portion of the housing  12 , such as keeping the transducer away from the floor  24  in order to not provide generalized vibration of the housing  12 . 
         [0048]    In certain embodiments the mount  32  below the well  16  may be absent entirely. In other embodiments, it may include soft, elastic, or even foamed, polymeric isolators in order to minimize vibration of the housing  12  through the floor  24 . Minimizing or eliminating the vibrational response of the mount  32  below the well  16  in response to the ultrasonic vibrations of the transducer  18  may be engineered to minimize vibration of the housing  12 . 
         [0049]    The assembly  14  may include a mount  36  that will hold a motor  50  or other motive system  50 . Typically, a cage  38  may extend from the mount  36  or elsewhere from the lid  30  that forms the backbone  30  for the convection drive assembly  14 . The cage  38  may operate both as a protection from moving parts, and for those moving parts, as well as a mount for baskets  40  to contain contact lenses  72 . In the illustrated embodiment, a basket  40  may be provided with a lid  42 , typically secured by a hinge  44  to the basket  40 . Thus, the basket  40  may be opened by pivoting the lid  42  about the hinge  44  in order to open the basket  40  for additional removal of the materials to be cleaned. 
         [0050]    Typically the impeller  46  may be of any suitable type. In the illustration, the impeller  46  may operate at the end of a shaft  48 , all protected within the cage  38 . In this way, the cage  38  protects each of the components therein from being touched by a user. Likewise, the shaft  48  with the impeller  46  on it may be rotated by the motor  50  without interference. 
         [0051]    An impeller  46  may be ducted, enclosed, or the like, rendering it a pump  46 , other mechanisms for inducing a vigorous flow may include magnetic stirrers, a buoyant plume, a bubbler, or other motive source. In certain embodiments, the motor  50  may be of any suitable type. However, it has been found suitable to use a direct current (DC) motor  50 . 
         [0052]    The motor  50  may be connected in a fixed relationship to the shaft  48 . Typically, the shaft  48  may be connected by an assembly, such as a sleeve or the like, to be driven by the motor  50 . Likewise, at an end of the shaft  48  opposite to the motor  50 , the impeller  46  may be configured as a propeller, fan, or the like suitable for inducing invigorous flows in forced convection to pass through the baskets  40 . Thus, the baskets  40  may be formed as a grid of members spaced apart, such as rods, or structural elements promoting the passage therethrough of substantial flows of liquid driven by the impeller  46  on the shaft  48 . 
         [0053]    The floor  52  of the well  16  is fitted to the mount  32 , or the well  16  may attach directly to the transducer  18 . As described hereinabove, the floor  52  may be isolated from the mount  32  or from the transducer  18  by an elastomeric element isolating the motion of the floor  52  of the well  16  away from the mount  32 , the housing  12  from the transducer, or both. That is, for example, the transducer  18  will vibrate ultrasonically, driving the floor  52  of the well  16  with it. In fact, that is the function of the transducer  18 , to vibrate the floor  52  at an ultrasonic frequency in order to generate waves in the liquid contained in the well  16 . 
         [0054]    Thus, it may be advisable to minimize sound, motion, and the like to isolate the well  16  from the mount  32 . In fact, the transducer  18  itself may be the exclusive bottom mount  32  for the well  16 . Nevertheless, in certain embodiments it has been found suitable to mold the housing  12 , including the mount  32  from a monolithic, homogeneous plastic. Thus, it has not always been found necessary to isolate the well  16  vibrationally from the mount  32 , but the best vibration is available when the transducer  18  is the exclusive lower mount  32  for the well  16 . 
         [0055]    The wall  54  of the well  16  may be sized and shaped in order to surround the cage  48  and the remaining portions of the convection drive assembly  14  that must be immersed within the well  16 . Similarly, the wall  54  may enclose a cavity  56  or interior  56  suitable for receiving and enclosing the baskets  40 , the cage  38 , and so forth. Typically, the cavity  56  or interior  56  of the well  16  is filled with a liquid, such as water. 
         [0056]    The water may include chemicals in order to provide a physiological saline-like pH suitable for the cleaning process. Likewise, other cleaning chemicals known in the art may be used as a matter of course. Thus, the vibration of the transducer  18 , transmitted by and through the floor  52  of the well  16 , generates ultrasonic waves passing through the liquid held in the cavity  56  or interior  56  of the well  16 . 
         [0057]    A shoulder  58  may be formed in the wall  54  of the well  16  to add increased section modulus to the well  16 . For example, the wall  54 , having a change in section, a change in direction, or both may present one or more shoulders  58  adding a stiffening rim to the well  16 . Likewise, the shoulder  58  may fit under the lid  28 , thus capturing the well  16  between the mount  32  and the lid  28 . 
         [0058]    A power source  60 , such as a power line  60 , may carry electrical current to drive the motor  50 . In certain embodiments, the power source  60  may be a line transmitting wall current at line voltage to a power supply within the cavity  26  in the housing  12 . For example, wall current is ubiquitous throughout the civilized world. Although the cyclic frequency in voltage will vary between countries, wall current and voltage are well established. 
         [0059]    In some embodiments, it may be advisable to reduce the voltage within the system  10  and particularly the voltage at which the motor  50  and transducer  18  operate. Therefore, it may be advisable to provide a power conditioning system within the cavity  26  of the housing  12  in order to provide to the transducer  18  and motor  50  the appropriate voltage and current. In certain embodiments, each of the transducer  18  and motor  50  may operate at line current. However, typically, this will not be the case. Instead, the transducer  18  and motor  50  will operate at much lower voltage than line voltage. 
         [0060]    Referring to  FIGS. 3-5 , while continuing to refer to  FIGS. 1-5 , a system  10  in accordance with the invention may include a hinge  62  on the lid  30  securing the lid  30  to the remainder of the housing  12 . That is, the housing  12  includes portions surrounded by the floor  24  and wall  22  as well as the lid  30 . Thus, the lid  30  may be secured by gravity, a snaplock or detent, no hinge, or a hinge  62  to the wall  22 . The lid  30  may be lifted, or pivoted to an open position, exposing the internal portions of the convection drive assembly  14 , such as the motor  50 , the cage  38 , the baskets  40 , the shaft  48 , the impeller  46 , and so forth. 
         [0061]    Referring to  FIG. 6 , while referring generally to  FIGS. 6-11 , where  FIG. 11  includes  FIG. 11A-11D , a schematic illustration of an eye  64  with the cornea  66  at the front thereof may bind by a fluid layer  68  a contact lens  72 . The surface tension in the fluid layer  68  will tend to hold the lens  72  against the eye  64 . Initially a new contact lens  72  will adhere to the eye  64  of a user over the cornea  66  by virtue of the surface tension of the fluid layer  68 . Over time, a contaminant layer  70  may develop in the surface or on the surface of the lens  72 , resulting in the rather tough and mechanically relatively strong contaminant layer  70 . 
         [0062]    Referring to  FIG. 7 , while continuing to refer generally to  FIGS. 1-11 , a lens  72  may be placed in a basket  40  in the apparatus  10  or system  10  in accordance with the invention. In the illustrated embodiment, the flow  74  is schematically illustrated driven by the impeller  46  on the shaft  48  powered by the motor  50 . The flow  74  is directed to flow across a surface of each of the lenses  72 . Meanwhile, the transducer  18  transmits ultrasonic vibrations into and through the floor  52  of the well  16 . 
         [0063]    Typically, the baskets  40  are set at an angle  76  with respect to the floor  52 . It has been found that functioning of the convective flow  74  operates better when the baskets  40  are not aligned vertically nor horizontally with respect to the floor  52 . Thus, for example, an angle from about 30 to about 60 degrees has been found suitable. Typically, the angle  76  may be at about 45 degrees with respect to the floor  52 . 
         [0064]    In the illustrated embodiment, the ultrasonic waves  78  in the fluid surrounding the baskets  40  and contact lenses  72  propagate throughout the cavity  56  of the well  16 . The liquid in the cavity  56  propagates the ultrasonic waves  78 , tending to create microcavitation on the surfaces of the lenses  72 . 
         [0065]    Referring to  FIG. 8 , while continuing to refer generally to  FIGS. 1-11 , a schematic illustration of a lens  72  and the attached contaminant layer  70  illustrates cavitation locations  80  or microcavitation bubbles  80  formed at the surface of the contact lens  72  where the contaminant layer  70  attaches. The adhesive force  82  of the contaminant layer with respect to the lens  72  is substantial. It has been found that microorganisms create a structure and the contamination layer  70  has structural integrity sufficient to support tensile forces  84  throughout the contaminant layer  70 . 
         [0066]    Also, the adhesive force  82  of the contaminant layer  70  binding to the lens  72  is appreciable and not overcome easily by the abrasion of washing. In contrast, the microcavitation bubbles  80  provide a force  86 , tending to push the contaminant layer  70  away from the surface  90  to which the layer  70  attaches. However, it has been found that ultrasonic waves alone are not particularly effective at permanently separating the contaminant layers  70  from the surface  90 . 
         [0067]    The cavitation bubbles  80  indeed originate and expand, thus providing a force  86  tending to separate the layer  70  from the surface  90 . However, microcavitation, like all cavitation, is a cyclic process in which bubbles  80  may form but may likewise collapse back on themselves. 
         [0068]    Thus, it has been found that the flow  74 , or the convective flow  74  driven by the impeller  46  along the surface  90  of the contact lens  72 , provides an additional benefit. To the extent that microcavitation bubbles  80  may rupture the contaminant layer  70 , the convective flow  74  may urge the discontinuity in the contaminant layer  70  to separate from the surface  90  of the lens  72 . 
         [0069]    Referring to  FIGS. 9-11 , where  FIG. 11  constitutes  FIGS. 11A-11D , the micro structure in a contact lens  72  and its overlying contaminant layer  70  connected to its surface  90  is presented schematically. As a practical matter, polymer chains are not entirely solid. 
         [0070]    At a molecular level, polymer strands  92  are formed leaving interstitial spaces  94  therebetween. The microorganisms that form the contaminant layer  70  exist within the interstitial spaces  94 . Thus, it is the mechanical structure of colonies of microbes that bind the contaminant layer  70  to the surface  90  by anchoring within the mechanical declivities, the like, interstitial spaces  94 , and thus anchoring to the polymer strands  92 , themselves. 
         [0071]      FIG. 10  represents an image at a layer, as seen in a scanning electron micrograph. Of course, many layers of polymeric web  92  or polymer strands  92  will exist within an actual lens  72 . Nevertheless, one can see the stranded nature of the polymer. 
         [0072]    Referring to  FIG. 11A , while continuing to refer generally to  FIGS. 1-11 , a convective flow  74  flowing over a contamination layer  90  may initially have little effect. Likewise, mechanical abrasion, cleansers, rubbing, and the like by users are not particularly effective against the contamination layer  70 . One surface passing against another in the presence of a liquid tends to be lubricated, minimizing friction and shear forces, and thus providing little if any tensile force on a contaminant layer in any direction. 
         [0073]    In  FIG. 11A , the convective flow  74  passes over the contamination layer or contaminant layer  70 , but the contaminant layer  70  is adhered to the contact lens by the growth of the contaminant layer  70  into the interstitial spaces  94  in the polymer  92 . Thus, the convective flow  74  by itself may not be particularly effective at removing the contaminant layer  70 . Similarly, mechanical abrasion, scrubbing, or rubbing, as mentioned, is not particularly effective. 
         [0074]    Moreover, the liquid between a contaminant layer  70  and any scrubbing mechanism, including brushes, fingers, or the like, tends to provide lubricity between the contaminant layer  70  and the implement of abrasion. If an abrasive material is sufficiently hard or effective to penetrate into the layer  70 , it is likewise hard enough to damage the surface  90  of the lens  72 , rendering it clouded and unsuitable for use. Moreover, any of the soft contact lenses or gas-permeable lenses tend to be light, mechanically soft, and may be ripped and thereby destroyed quite easily. 
         [0075]    Referring to  FIG. 11B , as microcavitation bubbles  80  begin to form on the surface  90  of a contact lens  72 , the contaminant layer  70  may separate locally. Eventually, as illustrated in  FIG. 11C , the contaminant layer  70  will rupture. Typically, due to the mechanical structure of the contaminant layer  70  and its embedding within the cavities  94  within the polymer  72 , the breaks in the contaminant layer  70  will typically return to their original place. If left they may completely re-attach. However, by vigorous action of the convective flow  74  as illustrated in  FIG. 11C , the convective flow  74  eventually begins to operate on the contaminant layer  70 , flowing between the contaminant layer  70  and the surface  90 , and also acting against the larger surface area exposed by the layer  70 . 
         [0076]    Referring to  FIG. 11D , the pieces of the contaminant layer  70  have been found to be mechanically separated by the convective flow  74 . This action takes advantage of the microcavitation bubbles  80  to initially provide a degree of mechanical separation between the layer  70  and the contact lens  72 . Then, relying on the fluid drag of a vigorous convective flow  74 , a mechanically produced drag force is strong enough to separate and tear loose the large area of the contaminant layer  70  presented to the convective flow  74 . 
         [0077]    Thus, the combination is most effective. Ultrasonic waves  78  cause microcavitation bubbles  80 , lifting the layer  70  sufficiently to break it and break it free locally. This initiation is augmented dramatically by the strong convective flow  70  lifting, pushing and proceeding to tear the layer  70  loose from the lens  72 . Thus, the experimental evidence shows that the film  70  or layer  70  of contaminants is torn off the lens  72  by the convective flow  74  much more effectively than, and in a way that cannot be done by, ultrasonic waves  78  acting alone. 
         [0078]    In sum, contact lenses are commonly cleaned using prior art systems and methods on a regular schedule to prevent protein deposits and other microbial growth and contaminations. However, most previously known cleaning techniques simply delay progress of the layer  70 , introduce harsh chemicals harmful to the eye, or both. Such may result in longer wear, but no real rollback of the effects of contamination. Eye infections still occur with use of prior art systems, some with devastating effect, including loss of vision, or loss of an eye due to infection. 
         [0079]    An apparatus and method in accordance with the invention were operated for cleaning and removing contaminants  80  from most substrates  72 , particularly including contact lenses  72 . Water in a saline solution was the fluid used, in the present design, and chemical additives were included for wetting, reducing interfacial energy, adjusting pH, and disinfecting, thus prolonging the life of contact lenses. The system services all types of lenses such as permanent, disposable, hard, soft, and gas-permeable lenses. 
         [0080]    Contaminants deposited on the surfaces developed as a growth of microbes, which tend to secure to the lens by propagating their mechanical structure into the apertures  94  in the matrix  92  of the substrate  72 . It was difficult to remove these contaminants without damaging the surface through aggressive cleaning, rubbing or harsh chemicals. Even ultrasonic cleaning did not provide clean lenses. Current technologies in ultrasonic or other subsonic agitations have proven ineffective, both in frequencies used and the lack of any hydrodynamic shear using cross-flow turbulence as induced in the system  10  in accordance with the invention. 
         [0081]    The present invention was operated as a contact lens cleaning device at selected ultrasonic frequencies. Induced shear flows due to convective flows in the turbulent domain of Reynolds numbers, were applied to clean the contained contact lenses  72 . In certain experiments, a cleaning solution was used to lower interfacial energy of the bonds between contaminants  70  and the contact lenses  72 . 
         [0082]    It has been found that three main components are involved in the reducing of contaminants and their removal. Initially, ultrasonic waves cause high and low pressure points throughout the substrate  72 , contamination layer  70 , and at the substrate-contaminant interface  90 . The substrate layer  72  and contaminant layer  70  have different physical properties, such as elastic modulus. Thus, the interface therebetween tends to provide cavitation bubbles  80 . 
         [0083]    These low and high pressure points or areas occur along the interface, and may occur internally in the lens  72  and contaminant layer  70 . Changes in pressure and temperature due to ultrasonic waves leads to microcavitation bubbles forming and collapsing along the interface surface  90  of the contact lens  72 . 
         [0084]    Vibrations induced from ultrasonic waves led to fractures or localized rupture of the contamination layer  70 . It is believed that pressure differentials between the substrate  72  and contaminant layers  70  apply low-cycle, high-load fatigue to the interfacial bonds between the substrate  72  and contaminants  70 . It is more than just the adhesion of the contaminant layer  70  to the lens  72 , but the mechanical strength of the actual biological structures created by microbes that embed in the interstices  94  in the polymer matrix  92  of the lens  72 . The structures maintain uncanny integrity, and separate as macroscopic films, visible in the cleaning fluid, rather than as particulate contaminants. 
         [0085]    Micro-cavitation  80  along the surface  90  or interface assists in separation and segregation, while a chemical agent facilitates the segregation by lowering the interfacial energy. However, a major influence in taking advantage of localized separation was shear from fluid drag acting against the initially separated or ruptured portions of the contaminant layer  70 . This was obtained by cross-flows operating in the turbulent flow regime. 
         [0086]    The result was reduced thickness of the hydrodynamic shear boundary layer. Thus any irregularity caused by microcavitation, breakage, and so forth was immediately amplified by applying fluid drag, causing shear forces to the parts of the contaminant layer extending out into the turbulent boundary layer and the bulk flow of the convective stream. The power of fluid drag then engaged and detached the compromised regions, tearing even larger fragments of the layer  70  from the substrate  72  by using the tensile strength of the film  70 . 
         [0087]    The construction of the housing  12  and lid  30  was of a rigid plastic material. It is contemplated that any suitable plastic, stainless steel, other metal, ceramic or similar material would likewise serve this purpose. The shape of the design of the lid  30  can either match the profile of the overall housing  12 , or simply fit the cover  28  around the well  16 , either inset into the cover  28  or overlapping, as here, to form the outer body contour of the housing  12 . 
         [0088]    The illustrated embodiment used a housing  12  generally circular with a circular well  16 , although a circular, oval, square or other cross section should serve. Nevertheless, a circular cross section provides the most efficient use of operating fluid in the cavity  56  of the well  16 . 
         [0089]    In further detail, the well  16  was designed to hold the cleaning solution. It was cylindrical, and spaced away from the outer wall of the housing. It was plastic in the original embodiment but may be made of stainless steel, plated steel, rigid plastic or any other similarly rigid material. Certain soft polymers may be used for soft housing  12 . 
         [0090]    The cage  38  and the contact holding basket  40  were designed to submerge into a cleaning solution used to disinfect the lens  72  and lower interfacial energy and surface tension. The cleaning solution held in the well  16  was filled to a level above the impeller  46 . The height of the liquid level affects how vigorous the flow  74  moves past the lens  72 , and may be selected to provide a turbulent Reynolds number. 
         [0091]    The baskets  40  were constructed of a rigid plastic material, but may be formed of plastic, metal, ceramic or other similar materials, with one to hold a left and one to hold a right contact separately in place in the same solution bath. The baskets were attached to a cage  38  covering the impeller  46  and drive shaft  48 . The cage  38  was secured to the lid  30  and extended down into the fluid in use. 
         [0092]    The impeller  46  may be of any suitable material, including silicone and soft polymers. In experiments, a rigid material was used. Thus steel, aluminum, plastic or any other suitable rigid material may serve. The impeller  46  was attached to an electric motor  50  built into the lid  30  to make the assembly  14 . 
         [0093]    Ultrasonic agitation was achieved using an piezoelectric, ultrasonic transducer  18  attached to the well  16 . A piezoelectric transducer  18  has a suitable frequency response, but a speaker or any other electrically powered device  18  capable of producing suitable ultrasonic frequencies may be used. The attachment of the transducer  18  to the well  16  was by a bonding agent, and may be by any suitable bonding agent, including adhesive, glue or welding technology. 
         [0094]    The cavity  26  was to be filled with a liquid for cooling or heating the well  16 , but liquid was found unnecessary. Thus, the cavity provided principally a degree of sound isolation 
         [0095]    Within the housing  12 , a cavity  20  separated from the fluid cavity  16  or well  16  was designed to hold power conditioning, electronics, circuit boards, or the like to control and power the DC motor and the transducer  18 . AC power may be used directly from a power cord  60  to supply line voltage from an electrical outlet. 
         [0096]    The advantages of the present invention include its ability to clean contact lenses  72  of accumulated proteins and other contaminant deposits  70  built, grown, or both onto the surface  90  of a contact lens  72 . An important result of a method and apparatus in accordance with the present invention is a fast, versatile, effective method to clean and thereby increase the safe and effective operational lifetime of contact lenses. 
         [0097]    The cleaner utilized an ultrasonic frequency between 30 kHz to 120 kHz from a piezoelectric transducer  18  directly mounted to the floor  52  of the well  16 . Ultrasonic frequencies effective to generate microcavitation were augmented by turbulent convection flows to remove from the lens surface  90  the film  70  of contaminants  70 . 
         [0098]    The convective shear flow, and even its vigor in the turbulent flow regime appear to be essential for greatest effectiveness and speed of cleaning. The mechanisms and effectiveness were not found in other ultrasonic contact lens cleaner devices. 
         [0099]    The turbulence may be produced using any method of propulsion from an impeller attached to a motor, a pump, ducted jet, or other motive driver. By using both suitable ultrasonic energy frequencies and vigorous shear flows, especially if including turbulence, the contaminants  70  were removed from the contact lens  72 , without damage to the soft plastic matrix of the contact lens  72 . 
         [0100]    Eliminating the contaminants  70  from the lens  72 , the life of the contact lens  72  can be prolonged, by mechanically undoing contaminant growth into the polymer matrix  92  within the lens  72 . Conventional rubbing or cleaning methods introducing large, localized forces that literally wear and tear the polymers strands  92  apart leaving the contact  72  unusable were proven unnecessary. The present invention provides more energy where actually needed, without the overwhelming mechanical loading where it can damage the lens  72 . 
         [0101]    While the foregoing written description of the invention enables one of similar technological knowledge to make and use what is considered presently to be the best mode thereof, those of similar skills will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.