Abstract:
Various embodiments of a non-powered actuator arm for controlling liquid flow to a fluid-filled lens are described herein. A vertical tweezer assembly compresses a reservoir of solution in a first vertical direction by lateral disposition of a slider mounted on the outside of the housing. The assembly may also be shaped to provide compression of the reservoir in a second horizontal direction by lateral disposition of a slider. In another embodiment, a housing may contain a piston that moves laterally within the housing and collapses the reservoir disposed adjacent to the piston and also within the housing. The housing may contain a plurality of compressible domes which can each be compressed to cause a local compression on the reservoir disposed within the housing. Compression of the reservoir causes liquid inflation of a lens module.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 61/391,827 filed Oct. 11, 2010, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field 
     Embodiments of the present invention relate to fluid-filled lenses and in particular to variable fluid-filled lenses. 
     2. Background 
     Basic fluid lenses have been known since about 1958, as described in U.S. Pat. No. 2,836,101, incorporated herein by reference in its entirety. More recent examples may be found in “Dynamically Reconfigurable Fluid Core Fluid Cladding Lens in a Microfluidic Channel” by Tang et al., Lab Chip, 2008, vol. 8, p. 395, and in WIPO publication WO2008/063442, each of which is incorporated herein by reference in its entirety. These applications of fluid lenses are directed towards photonics, digital phone and camera technology and microelectronics. 
     Fluid lenses have also been proposed for ophthalmic applications (see, e.g., U.S. Pat. No. 7,085,065, which is incorporated herein by reference in its entirety). In all cases, the advantages of fluid lenses, such as a wide dynamic range, ability to provide adaptive correction, robustness, and low cost have to be balanced against limitations in aperture size, possibility of leakage, and consistency in performance. The &#39;065 patent, for example, has disclosed several improvements and embodiments directed towards effective containment of the fluid in the fluid lens to be used in ophthalmic applications. Power adjustment in fluid lenses has been effected by injecting additional fluid into a lens cavity, by electrowetting, application of ultrasonic impulse, and by utilizing swelling forces in a cross-linked polymer upon introduction of a swelling agent such as water. 
     BRIEF SUMMARY 
     In an embodiment, an actuator for a sealed fluid filled lens includes a tweezer assembly including a fixed end, a free end, a top pincer, and a bottom pincer. A reservoir is disposed within the tweezer assembly, wherein the reservoir is in fluid communication with the fluid filled lens. The reservoir is placed parallel to the length of the tweezer assembly between the fixed end and the free end such that flexing the tweezer assembly compresses the reservoir along a length of the reservoir. A slider is laterally moveable along an outer surface of the tweezer assembly, wherein, movement of the slider from one end of the tweezer assembly to the other end flexes the tweezer assembly. 
     In another embodiment, an actuator for a sealed fluid filled lens includes a housing and a reservoir. The reservoir is disposed within the housing and placed parallel to the length of the housing. A piston is placed inside the housing and is attached to an end of the reservoir, wherein lateral movement of the piston from a first end of the housing to a second end of the housing collapses the reservoir onto itself. A slider moves laterally along an outer surface of the housing, wherein the movement of the slider from the first end of the housing to the second end of the housing pushes the piston, causing the reservoir to collapse onto itself. 
     In another embodiment, an actuator for a sealed fluid filled lens includes a housing and a plurality of domes placed along the outer surface of the housing. The housing includes an inner half and an outer half. The plurality of domes includes a plurality of meta-stable domes placed along the outer surface of the inner half of the housing and a plurality of bi-stable domes placed along the outer surface of the outer half of the housing, wherein each bi-stable dome is placed directly across from a respective meta-stable dome. The actuator further includes a reservoir disposed within the housing between the plurality of meta-stable domes and the plurality of bi-stable domes, wherein the reservoir is in fluid communication with the fluid filled lens. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES 
       The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments of the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. 
         FIG. 1  illustrates a perspective view of an embodiment of a fluid filled lens system. 
         FIG. 2   a  illustrates a perspective view of an exemplary vertical tweezer actuator. 
         FIG. 2   b  illustrates a cross-section view of the vertical tweezer actuator of  FIG. 2   a.    
         FIG. 3  illustrates a perspective view of an embodiment of an exemplary slider. 
         FIG. 4   a  illustrates a side view of a slider in a first position on the vertical tweezer actuator, according to an embodiment. 
         FIG. 4   b  illustrates a side view of a slider in a second position on the vertical tweezer actuator, according to an embodiment. 
         FIG. 4   c  illustrates a side view of a slider in a third position on the vertical tweezer actuator, according to an embodiment. 
         FIG. 5   a  illustrates a perspective view of an exemplary horizontal tweezer actuator. 
         FIG. 5   b  illustrates a cross-section view of the horizontal tweezer actuator of  FIG. 5   a.    
         FIG. 6   a - d  illustrate perspective views of embodiments of an exemplary slider. 
         FIG. 7   a  illustrates a top-down view of a slider in a first position on the horizontal tweezer actuator, according to an embodiment. 
         FIG. 7   b  illustrates a top-down view of a slider in a second position on the horizontal tweezer actuator, according to an embodiment. 
         FIG. 7   c  illustrates a top-down view of a slider in a third position on the horizontal tweezer actuator, according to an embodiment. 
         FIG. 8  illustrates a perspective cut-away view of an exemplary piston-driven actuator. 
         FIG. 9   a  illustrates a side cut-away view of a slider in a first position on the piston-driven actuator, according to an embodiment. 
         FIG. 9   b  illustrates a side cut-away view of a slider in a second position on the piston-driven actuator, according to an embodiment. 
         FIG. 9   c  illustrates a side cut-away view of a slider in a third position on the piston-driven actuator, according to an embodiment. 
         FIG. 10  illustrates an exploded perspective view of an exemplary sandwich dome actuator. 
         FIG. 11  illustrates a cross-section demonstrating the actuation principle of a bi-stable dome, according to an embodiment. 
         FIG. 12   a - d  illustrate cross-sections demonstrating the actuation principle of a meta-stable dome, according to an embodiment. 
     
    
    
     Embodiments of the present invention will be described with reference to the accompanying drawings. 
     DETAILED DESCRIPTION 
     Although specific configurations and arrangements are discussed, it should be understood that this is done for illustrative purposes only. A person skilled in the pertinent art will recognize that other configurations and arrangements can be used without departing from the spirit and scope of the present invention. It will be apparent to a person skilled in the pertinent art that this invention can also be employed in a variety of other applications. 
     It is noted that references in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure or characteristic is described in connection with an embodiment, it would be within the knowledge of one skilled in the art to effect such feature, structure or characteristic in connection with other embodiments whether or not explicitly described. 
     Fluid lenses have important advantages over conventional means of vision correction, such as rigid lenses and contact lenses. First, fluid lenses are easily adjustable. Thus, a presbyope who requires an additional positive power correction to view near objects can be fitted with a fluid lens of base power matching the distance prescription. The user can then adjust the fluid lens to obtain additional positive power correction as needed to view objects at intermediate and other distances. 
     Second, fluid lenses can be adjusted continuously over a desired power range by the wearer. As a result, the wearer can adjust the power to precisely match the refractive error for a particular object distance in a particular light environment. Thus, fluid lenses allow adjustment of power to compensate for alteration of the natural depth of focus of the eye that depends on the wearer&#39;s pupil size, which is in turn dependent on the ambient light level. 
     Third, although 20/20 vision, which corresponds to an image resolution of 1 minute of arc ( 1/60 degree) is generally acknowledged to represent an acceptable quality of vision, the human retina is capable of finer image resolution. It is known that a healthy human retina is capable of resolving 20 seconds of arc ( 1/300 degree). Corrective eyeglasses designed to enable a patient to achieve this superior level of vision have a resolution of about 0.10 D or better. This resolution can be achieved with continuously adjustable fluid lens elements. 
     In an embodiment of a fluid lens assembly, one or more fluid lenses may be provided with its own actuation system, so that a lens for each eye can be adjusted independently. This feature allows wearers, such as anisometropic patients, to correct any refractive error in each eye separately, so as to achieve appropriate correction in both eyes, which can result in better binocular vision and binocular summation. 
       FIG. 1  illustrates a perspective view of a fluid filled lens system  100  according to an embodiment of the present invention. The fluid filled lens system  100  includes: a bridge  102 , left and right lens module  104 , left and right hinge  108 , left and right actuator arm  110 , and left and right distal end  112  of actuator arms  110 . It should be appreciated that all descriptions of each component listed apply to both the left and right versions of each component in the system. Hinge  108  connects lens module  104  to actuator arm  110 . Actuator arm  110  operates to compress a reservoir (not shown) and transfer fluid between the reservoir and lens module  104 . Distal end  112  of actuator arm  110  is shaped to fit over the wearer&#39;s ear. 
     In an embodiment, lens module  104  further comprises a rim  106  which defines the edge of lens module  104 . Lens module  104  may further include a flexible back surface provided by, for example, a flexible membrane (not shown) stretched flat over the edge of a rigid optical lens. To change the optical power of lens module  104 , the membrane may be inflated through the addition of fluid from a reservoir (not shown). The reservoir is placed within actuator arm  110  and is attached to lens module  104  via a connecting tube (not shown) placed within hinge  108 . The connecting tube is designed to be impermeable to the fluid contained therein. In an embodiment, the overall assembly including lens module  104 , the connecting tube, and the reservoir is designed to maintain a seal excluding fluids and air for an overall use period of two years or more. In an embodiment, the connecting tube is thin in order to be accommodated within a hinge cavity. In an embodiment, the connecting tube is less than 2.0 mm in outer diameter and less than 0.50 mm in wall thickness, in order to maintain an adequate flow of fluid. In an embodiment, the connecting tube is capable of being bent by an angle of no less than 60 degrees. In an embodiment, the connecting tube is capable of being bent by an angle of no less than 45 degrees without crimping. In an embodiment, the connecting tube is durable to repeated flexing of the hinge. 
     Designs of actuator arm  110 , and methods of compressing the reservoir and changing the optical power of lens module  104  are described herein. 
       FIG. 2   a  illustrates a perspective view of an embodiment of actuator arm  110 . In this embodiment, a vertical tweezer actuator  200  includes a tweezer assembly  218  with a fixed end  202 , a free end  204 , a top pincer  206 , and a bottom pincer  208 . A reservoir  210  is disposed between the top and bottom pincers. Vertical tweezer actuator  200  further includes a brace  212 , mechanical stops  214   a  and  214   b , and a slider  216 . In an embodiment, slider  216  fits over top pincer  206  and bottom pincer  208  and can slide laterally along the length of tweezer assembly  218  between two mechanical stops  214   a  and  214   b . In an embodiment, slider  216  can move laterally along the inner side of tweezer assembly  218  as illustrated in  FIG. 2   a . The inner side is understood to be the side facing towards the wearer&#39;s head. 
       FIG. 2   b  provides a cross-section view of vertical tweezer actuator  200 .  FIG. 2   b  also provides a view of ball bearings  220  placed between slider  216  and both top pincer  206  and bottom pincer  208 . Ball bearings  220  provide low friction contact between slider  216  and the rest of the assembly. Other bearing designs may be utilized for the movement of the slider, for example, roller sliders, plain bearings or dovetail bearings.  FIG. 2   b  also provides an exemplary view of brace  212  which provides support for top pincer  206  and bottom pincer  208 . Although  FIG. 2   b  shows top pincer  206  and bottom pincer  208  with a curved shape, other shapes may also be used, e.g. a flat shape to cause further compression on reservoir  210 . 
       FIG. 3  illustrates a perspective view of slider  216  removed from the rest of the assembly. In an embodiment, slider  216  has a rounded cuff shape. Other shapes for slider  216  may also be used, e.g. a bracket shape. 
       FIG. 4   a  illustrates a side view of the vertical tweezer actuator  400  with slider  216  in a first position against mechanical stop  214   a .  FIG. 4   b  illustrates the vertical tweezer actuator  402  with a lateral movement  404  of slider  216  along the inner side of the tweezer assembly  218  to a second position between fixed end  202  and free end  204  of the tweezer assembly  218 . The movement causes top pincer  206  and bottom pincer  208  to flex toward each other and compress reservoir  210 .  FIG. 4   c  illustrates the vertical tweezer actuator  406  with a lateral movement  408  of slider  216  along the inner side of the tweezer assembly  218  to a third position against mechanical stop  214   b . The movement to the third slider position causes further compression of reservoir  210  to a maximal state of compression. In an embodiment, as slider  216  is moved away from free end  204  towards fixed end  202  laterally along the inner side of the tweezer assembly  218 , the compressing force on reservoir  210  is released, and reservoir  210  springs back to its original shape, temporarily causing low pressure on the fluid, and thus pulling fluid back from lens module  104 . 
       FIG. 5   a  illustrates a perspective view of an embodiment of actuator arm  110 . In this embodiment, a horizontal tweezer actuator  500  includes a tweezer assembly  516  with a fixed end  502 , a free end  504 , a fixed pincer  506 , and a free pincer  508 . A reservoir  510  is disposed between fixed pincer  506  and free pincer  508 . Vertical tweezer actuator  500  further includes mechanical stops  512   a  and  512   b , and a slider  514 . In an embodiment, slider  514  fits around fixed pincer  506  and free pincer  508  and can slide laterally along the length of tweezer assembly  516  between mechanical stops  512   a  and  512   b.    
     In an embodiment, both fixed pincer  506  and free pincer  508  may be of any shape or size. In an example, fixed pincer  506  may have a bracket shape that is larger than a bracket shape of free pincer  508 . 
       FIG. 5   b  provides a cross-section view of horizontal tweezer actuator  500 . Ball bearings  518  are placed between slider  514  and either one or both pincers. Ball bearings  518  provide low friction contact between slider  514  and the outer surface of tweezer assembly  516 . In an embodiment, ball bearings  520  may also be included to provide a rolling contact between slider  514  and reservoir  510 . Ball bearings  520  require a higher force to overcome static friction than ball bearings  518  and will prevent slider  514  from unwanted movement. Other bearing designs may be utilized for the movement of slider  514 , for example, roller sliders, plain bearings or dovetail bearings. 
       FIG. 6   a - d  illustrate embodiments of slider designs for use with horizontal tweezer actuator  500 .  FIG. 6   a  illustrates a perspective view of an open bracket slider  600 .  FIG. 6   b  illustrates a perspective view of a closed bracket slider  602 .  FIG. 6   c  illustrates a perspective view of open bracket slider  600  further showing a connector  604  and a sliding loop  606 . Sliding loop  606  fits more closely around tweezer assembly  518  than either open bracket slider  600  or closed bracket slider  602 . Connector  604  attaches sliding loop  606  to open bracket slider  600 . In an embodiment, slider loop  606  uses ball bearings (not shown) to make contact to either one or both pincers or reservoir  510  as discussed previously. The inclusion of slider loop  606  provides a more constant force acting upon the pincers as slider  600  is disposed along the length of tweezer assembly  516 .  FIG. 6   d  illustrates sliding loop  606  and connector  604  as described above within closed bracket slider  602 . 
       FIG. 7   a  illustrates a top-down view of the horizontal tweezer actuator  700  with slider  514  in a first position against mechanical stop  512   a .  FIG. 7   b  illustrates the horizontal tweezer actuator  702  with a lateral movement  704  of slider  514  along the length of tweezer assembly  516  to a second position between fixed end  502  and free end  504  of tweezer assembly  516 . The movement causes free pincer  508  to flex towards fixed pincer  506  and compress reservoir  510 .  FIG. 7   c  illustrates the horizontal tweezer actuator  706  with a lateral movement  708  of slider  514  along the length of tweezer assembly  516  to a third position against mechanical stop  512   b . The movement to the third slider position causes further compression of reservoir  510  to a maximal state of compression. In an embodiment, as slider  514  is moved away from free end  504  towards fixed end  502  laterally along the length of tweezer assembly  516 , the compressing force on reservoir  510  is released, and reservoir  510  springs back to its original shape, temporarily causing low pressure on the fluid, and thus pulling fluid back from lens module  104 . 
       FIG. 8  illustrates a perspective view of an embodiment of actuator arm  110 . In this embodiment, a piston-driven actuator  800  includes a housing  812 , a piston  802  disposed within housing  812 , and a reservoir  804  disposed within housing  812  and with a distal end  806  attached to piston  802 . The piston-driven actuator  800  further includes mechanical stops  808   a  and  808   b , and a slider  810 . In an embodiment, slider  810  fits around the outer surface of housing  812  and can slide laterally along the length of housing  812  between mechanical stops  808   a  and  808   b.    
     In an embodiment, piston  802  is a magnet with a fixed polarity. In an embodiment, slider  810  is a magnet with a fixed polarity opposite the polarity of piston  802 . Lateral movement of slider  810  along the length of housing  812  causes piston  802  to also move laterally within housing  812  due to magnetic forces between piston  802  and slider  810 . Slider  810  may have any shape, such as that illustrated, for example, in  FIG. 6   a  or  FIG. 6   b.    
       FIG. 9   a  illustrates a side view of the piston-drive actuator  900  with slider  810  in a first position against mechanical stop  808   a .  FIG. 9   b  illustrates the piston drive actuator  902  with a lateral movement  904  of slide&#39;  810  along the length of housing  812  to a second position between mechanical stops  808   a  and  808   b . Lateral movement  904  causes piston  802  to move laterally as well, thereby pushing distal end  806  of reservoir  804  closer to hinge  108  and collapsing reservoir  804 .  FIG. 9   c  illustrates the piston-drive actuator  906  with a lateral movement  908  of slider  810  along the length of housing  812  to a third position against mechanical stop  808   b . Lateral movement  908  to the third slider position causes further collapsing of reservoir  804  to a maximal state. In an embodiment, as slider  810  is moved away from hinge  108  laterally along the length of housing  812 , piston  802  is moved laterally away from hinge  108  as well. This causes reservoir  804  to spring back to its original shape, temporarily causing low pressure on the fluid, and thus pulling fluid back from lens module  104 . 
       FIG. 10  illustrates an exploded perspective view of another embodiment of actuator arm  110 . In this embodiment, a sandwich dome actuator  1000  includes a housing  1010  with an inner half  1002  and an outer half  1004 , a plurality of meta-stable domes  1006  on inner half  1002  of housing  1010 , and a plurality of bi-stable domes  1008  on outer half  1004  of housing  1010 . A reservoir  1012  is disposed within housing  1010  and placed between meta-stable domes  1006  and bi-stable domes  1008 . In an embodiment, each bi-stable dome  1008  is placed directly across from a respective meta-stable dome  1006 . Compression of either bi-stable dome  1008  or a respective meta-stable dome  1006  causes compression on a portion of reservoir  1012  between the domes. 
     Plurality of bi-stable domes  1008  across from plurality of meta-stable domes  1006  along the outer surface of housing  1010  allow the wearer to carefully control the state of compression on reservoir  1012  disposed within housing  1010  and between the domes. Bi-stable domes  1008  allow for a local maximum compression while meta-stable domes  1006  allow for a local variable state of compression. Releasing the compression on reservoir  1012  by changing the states of the domes causes reservoir  1012  to spring back to its original shape, temporarily causing low pressure on the fluid, and thus pulling fluid back from lens module  104 . 
     In an embodiment, either bi-stable domes  1008  or meta-stable domes  1006  are pressed in order starting with the domes located the furthest from hinge  108  and moving inward towards hinge  108  in order to control the amount of total compression on reservoir  1012 . In an embodiment, compressing all of either bi-stable domes  1008  or meta-stable domes  1006  along the outside of housing  1010  causes a maximal state of compression on reservoir  1012 . 
       FIG. 11  illustrates a cross-section of a single bi-stable dome  1100  across from a respective meta-stable dome  1102 , further depicting the operation of bi-stable dome  1100 . Bi-stable dome  1100  exists in either a relaxed state  1104  or a compressed state  1106 . In relaxed state  1104 , Bi-stable dome  1100  is pushed out away from reservoir  1012  in a direction perpendicular to the length of housing  1010 . In compressed state  1106 , Bi-stable dome  1100  is pushed inward towards reservoir  1012  in a direction perpendicular to the length of housing  1010 . Compressed state  1106  causes a local maximum compression on the portion of reservoir  1012  between compressed bi-stable dome  1100  and respective meta-stable dome  1102 . Applying a first force  1108  to the outer surface of bi-stable dome  1100  switches it from relaxed state  1104  to compressed state  1106 . Applying a second force  1110  switches it from compressed state  1106  back to relaxed state  1104 . Either force may be applied by any external means. For example, either force may be applied by the wearer&#39;s finger pressing on the bi-stable dome. First force  1108  and second force  1110  may be the same magnitude or different magnitudes. Each force must be larger than a given threshold magnitude in order to switch the bi-stable dome  1100  between either state. 
       FIG. 12   a - d  illustrate cross-sections of a single bi-stable dome  1200  across from a respective meta-stable dome  1202  further depicting the operation of meta-stable dome  1202 . Meta-stable dome  1202  can exist in any state between a fully relaxed state  1204  and a fully compressed state  1206 . Both fully relaxed state  1204  and fully compressed state  1206  are analogous to those of bi-stable dome  1100  as described previously.  FIG. 12   a  illustrates meta-stable dome  1202  in fully relaxed state  1204 . One or more forces may be applied to the surface of meta-stable dome  1202  to push it inward towards reservoir  1012 . For example,  FIG. 12   b  illustrates a first force  1208  pushing meta-stable dome  1202  from fully relaxed state  1204  to a first state  1210  causing a first compression upon reservoir  1012 .  FIG. 12   c  illustrates a second force  1212  pushing meta-stable dome  1202  to a second state  1214  causing a second compression upon reservoir  1012  greater than the first compression.  FIG. 12   d  illustrates a third force  1216  pushing meta-stable dome  1202  to fully compressed state  1206  causing a local maximum compression on the portion of reservoir  1012  between bi-stable dome  1200  and meta-stable dome  1202 . Meta-stable dome  1202  may be returned to fully relaxed state  1204  by pressing respective bi-stable dome  1200  into its compressed state thus pushing meta-stable dome  1202  back out away from reservoir  1012 . 
     The above example is not intended to be limiting in its description of the operation. It can be appreciated that any number of forces of varying magnitude larger than a given threshold can be used to change the state of the meta-stable dome. The forces may be applied by any external means. For example, the forces may be applied by the wearer&#39;s finger pressing on the meta-stable dome. 
     The pieces of the various actuator assemblies described, for example, but not limited to, the tweezer assembly, housing, slider, ball bearings, meta-stable domes and bi-stable domes etc, may be manufactured through any suitable process, such as metal injection molding (MIM), cast, machining, plastic injection molding, and the like. The choice of materials may be further informed by the requirements of mechanical properties, temperature sensitivity, optical properties such as dispersion, moldability properties, or any other factor apparent to a person having ordinary skill in the art. 
     The fluid used in the fluid lens may be a colorless fluid, however, other embodiments include fluid that is tinted, depending on the application, such as if the intended application is for sunglasses. One example of fluid that may be used is manufactured by Dow Corning of Midland, Mich., under the name “diffusion pump oil,” which is also generally referred to as “silicone oil.” 
     The fluid lens may include a rigid optical lens made of glass, plastic, or any other suitable material. Other suitable materials include, for example and without limitation, Diethylglycol bisallyl carbonate (DEG-BAC), poly(methyl methacrylate) (PMMA), and a proprietary polyurea complex, trade name TRIVEX (PPG). 
     The fluid lens may include a membrane made of a flexible, transparent, water impermeable material, such as, for example and without limitation, one or more of clear and elastic polyolefins, polycycloaliphatics, polyethers, polyesters, polyimides and polyurethanes, for example, polyvinylidene chloride films, including commercially available films, such as those manufactured as MYLAR or SARAN. Other polymers suitable for use as membrane materials include, for example and without limitation, polysulfones, polyurethanes, polythiourethanes, polyethylene terephthalate, polymers of cycloolefms and aliphatic or alicyclic polyethers. 
     The connecting tube may be made of one or more materials such as TYGON (polyvinyl chloride), PVDF (Polyvinyledene fluoride), and natural rubber. For example, PVDF may be suitable based on its durability, permeability, and resistance to crimping. 
     The housing and tweezer assembly may be any suitable shape, and may be made of plastic, metal, or any other suitable material. In an embodiment, the housing and tweezer assembly are made of a lightweight material such as, for example and without limitation, high impact resistant plastics material, aluminum, titanium, or the like. In an embodiment, the housing and tweezer assembly may be made entirely or partly of a transparent material. 
     The reservoir may be made of, for example and without limitation, Polyvinyledene Difluoride, such as Heat-shrink VITON®, supplied by DuPont Performance Elastomers LLC of Wilmington, Del., DERAY-KYF 190 manufactured by DSG-CANUSA of Meckenheim, Germany (flexible), RW-175 manufactured by Tyco Electronics Corp. of Berwyn, Pa. (formerly Raychem Corp.) (semirigid), or any other suitable material. Additional embodiments of the reservoir are described in U.S. Pat. Pub. No. 2011/0102735 which is incorporated by reference in its entirety. 
     It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the present invention as contemplated by the inventor(s), and thus, are not intended to limit the present invention and the appended claims in any way. 
     The present invention has been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed. 
     The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance. 
     The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.