Abstract:
Pipette tip grids with holes for holding pipette tips and packages for the grids are provided. A pipette tip grid package comprises a grid, a base for supporting the grid, and a lock mechanism coupled to the grid and configured to externally engage with a sidewall of the base. The sidewall of the base also supports the grid. The package also can have a detachable cover for the grid, and, the lock mechanism can be external to the cover as well as the base. In some embodiments, the grids are stackable and the cover engages the topmost grid of the stack. Together, the cover, the base, and the sidewalls of the one or more stacked pipette tip grids form a protective case around pipette tips in the one or more grids.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to the field of laboratory equipment, and more particularly to arrays of disposable pipette tips for pipetting systems. 
     2. Description of the Prior Art 
     In chemical, biological, pharmaceutical, and similar fields, laboratory handling of very small quantities of fluids is commonly performed with pipettes. In many instances, automated pipetting systems allow multiple fluid samples to be handled rapidly and in parallel while maintaining a very high degree of precision over the sample quantities. Often, such automated pipetting systems employ disposable pipette tips to prevent contamination from one sample to the next. Typically, pipette tips are provided to an automated pipetting system in a pipette tip rack or grid. In the pipette tip grid, the tips are typically arranged in rows where the number of tips in a row is equal to the number of parallel pipettes in the automated pipetting system. Accordingly, the automated pipetting system can readily pick up a row or multiple rows of tips from the grid. 
     It will be appreciated that disposable pipette tips need to be kept free of contamination to be acceptable for most applications. Accordingly, grids are packaged for shipping, handling, and storage.  FIG. 1  illustrates a prior art pipette tip grid  100  supported within a protective box  102 . The box  102  includes a hinged lid  104  that pivots to open and close. As can be seen from  FIG. 2 , locking tabs  106  attached to the grid  100  secure the grid  100  within the box  102 . To release the grid  100  from the box  102 , the locking tabs  106  are depressed and then the grid  100  can be removed. As shown in  FIG. 3 , when the lid  104  is closed the locking tabs  106  are also covered. Accordingly, to take the grid  100  out of the case  102  requires opening the lid  104  which exposes tops of pipette tips  108  to contamination. 
     As can be seen from  FIG. 4 , the grids  100  of the prior art can be stacked. When stacked, the pipette tips  108  in one grid  100  nest in the pipette tips  108  of the grid  100  beneath. Unfortunately, the lid  104  will not close over a stack of grids  100 , and therefore the lid  104  is preferably removed, as shown. It can be seen that the tops of the pipette tips  108  are exposed, as are the sides of the pipette tips  108 . 
     Accordingly, what is needed is improved packaging for pipette tips. 
     SUMMARY 
     The present invention provides grids with holes for holding pipette tips and packages for the pipette tip grids. A pipette tip grid package comprises a pipette tip grid, a base for supporting the pipette tip grid, and a lock mechanism coupled to the pipette tip grid. The lock mechanism is configured to externally engage with a sidewall of the base to secure the pipette tip grid to the base. Releasing the lock mechanism allows the pipette tip grid to be detached from the base. 
     The sidewall of the base also supports the pipette tip grid, and in some embodiments the pipette tip grid nests inside of the sidewall. In some embodiments, a flange on the pipette tip grid rests on a top edge of the sidewall of the base. In other embodiments, the sidewall includes an interior ledge for supporting a bottom edge of the pipette tip grid. Further embodiments may employ both the flange on the pipette tip grid and the interior ledge of the sidewall. In some embodiments, the pipette tip grids are configured to be stacked. 
     Additional embodiments of the pipette tip grid package further comprise a cover supported by the pipette tip grid and detachable therefrom. Preferably, the lock mechanism is external to the cover as well as the base. In this way, without having to remove the cover from the pipette tip grid, the lock mechanism can be accessed to detach the pipette tip grid from the base, so that the pipette tip grid and the cover are removed together. Advantageously, when multiple pipette tip grids are stacked on the base, the cover engages the topmost pipette tip grid of the stack. Together, the cover, the base, and the sidewalls of the one or more stacked pipette tip grids form a protective case around pipette tips on the one or more grids. 
     Still other embodiments of the pipette tip grid package include a lock mechanism that allows stacked grids to be interlocking. An exemplary interlocking pipette tip grid package includes a first pipette tip grid including a lock mechanism configured to externally engage with a base, and a second pipette tip grid including a lock mechanism configured to externally engage with first pipette tip grid. Preferably, the first and second pipette tip grids are interchangeable. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a pipette tip grid supported in a case according to the prior art. 
         FIG. 2  is a perspective view of the pipette tip grid of  FIG. 1  removed from the case. 
         FIG. 3  is a perspective view of the case of  FIG. 1  within a closed lid. 
         FIG. 4  is a perspective view of multiple pipette tip grids in a stacked arrangement according to an embodiment of the prior art. 
         FIG. 5  is a perspective view of a housing closed around a stackable pipette tip grid according to an embodiment of the present invention. 
         FIG. 6  is a partially exploded view of the housing of  FIG. 5 . 
         FIG. 7  is a fully exploded view of the stackable pipette grid of  FIG. 5 . 
         FIG. 8  is a perspective view of the housing closed around multiple stackable pipette tip grids according to an embodiment of the present invention. 
         FIG. 9  is a top view of a stackable pipette grid according to an embodiment of the present invention. 
         FIG. 10  is a cross-sectional view of the grid of  FIG. 8 . 
         FIG. 11  is a cross-sectional view of a lock mechanism of the grid of  FIG. 8 . 
         FIG. 12  is a cross-sectional view of a stackable pipette grid engaged to a base according to another embodiment of the invention. 
         FIG. 13  is a cross-sectional view of a lock mechanism of the grid of  FIG. 12 . 
         FIG. 14  is a cross-sectional view of the grid of  FIG. 12  engaged to another such grid according to another embodiment of the invention. 
         FIG. 15  is a cross-sectional view of the lock mechanisms of the interlocked grids of  FIG. 14 . 
         FIG. 16  is a perspective view of multiple grids of  FIG. 12  in an interlocked stacked arrangement on a base and with a cover. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention provides a stackable pipette tip grid including a lock mechanism and an associated case for the pipette tip grid that overcomes problems with the prior art. One or more stackable grids can be disposed between a base and a cover of the case. The lock mechanism of the pipette tip grid secures the grid to the base. Advantageously, the lock mechanism is disposed externally to both the base and the cover so that the lock mechanism can be accessed without removing the cover from the grid. Accordingly, the lock mechanism allows the grid to be removed from the base while the cover remains in place over the grid. To better understand the advantages of the present invention, the stackable pipette tip grid will be described generally with respect to  FIGS. 5-10 , and an embodiment of the lock mechanism will be described with respect to  FIG. 11 . 
       FIG. 5  shows a perspective view of an exemplary pipette tip grid package  200  according to an embodiment of the invention. As configured in  FIG. 5 , a case of the package  200  encloses a stackable pipette tip grid  202  (not shown).  FIG. 6  shows a partially exploded perspective view of the package  200 . The case of the package  200  includes a cover  204  and a base  206 . As can be seen from  FIG. 6 , the grid  202  includes a lock mechanism  208 . Further, the grid  202  and the cover  204  together comprise a grid assembly  210  that can be detached from the base  206  as a unit. 
     It can be seen from  FIGS. 6 and 7  that the base  206  is essentially a box opened at a top side. Accordingly, the base  206  includes a bottom  212 , opposite the opened top side of the box, and a sidewall  214  that extends from the bottom  212  to form four sides of the box. In some embodiments of the present invention, the bottom  212  and the sidewall  214  are integral, for example, by being formed together by a process such as injection molding. In other embodiments, the bottom  212  and the sidewall  214  are bonded together to form the base  206 . 
     The base  206  is configured to receive the grid  202  such that the grid  202  nests securely inside of the base  206 . In some instances, the grid  202  is fully enclosed by the base  206 . To this end, the sidewall  214  of the base  206  can include an interior ledge  216 . A bottom edge  218  of the grid  202  rests on the interior ledge  216  when the grid  202  is set inside of the base  206 . Alternately, the grid  202  can include a flange  220  that rests on a top edge  222  of the sidewall  214 . In further embodiments, the base  206  includes the interior ledge  216 , and the grid  202  includes the flange  220  as shown in  FIGS. 6 and 7 . 
     As can be seen, the grid  202  includes a plurality of holes  224  for receiving pipette tips  226 . In some embodiments, the grid  202  can support  96  pipette tips  226  in a square array, though it will be appreciated that the grid  202  can, in principle, be configured to support any number of pipette tips  226  in any pattern or arrangement according to the needs of different pipetting systems. One alternative pattern is a hexagonal array, for example. 
     When the grid  202  is nested in the base  206 , ends  228  of the pipette tips  226  are enclosed by the base  206  to keep the ends  228  free from contamination and damage. Similarly, the cover  204  is configured to engage the grid  202  to cover the tops of the pipette tips  226  to protect the tops and prevent contamination. In those embodiments in which the grid  202  includes the flange  220 , the cover  204  can rest on the flange  220  when the two are fully engaged. As shown in  FIG. 6 , the entire grid assembly  210  can be advantageously removed from the base  206  while the cover  204  remains in place over the grid  202 . 
       FIG. 8  shows multiple grids  202  in a stacked arrangement between the base  206  and the cover  204 . In the stacked arrangement, pipette tips  226  in one grid  202  nest in the pipette tips  226  of the grid  202  beneath. Additionally, the bottom edge  218  of one grid  202  rests on the flange  220  of the grid  202  beneath. It can be seen from the comparison of the stacked arrangement of  FIG. 8  to the prior art stacked arrangement shown in  FIG. 4  that the stacked arrangement of the present invention provides advantages over the prior art. For example, the sidewalls of the grids  202 , together with the cover  204  and base  206 , create a complete barrier to contamination that is absent in the prior art. Further, the cover  204  works with the stacked arrangement regardless of the number of stacked grids  202 . 
     As noted above, the grid  202  further includes a lock mechanism  208 . The lock mechanism  208  is coupled to the grid  202  and configured to externally engage with the sidewall  214  of the base  206 .  FIGS. 9-11  show the relationship of the lock mechanism  208  to the base  206  and cover  204  in more detail.  FIG. 9  is a top view of the pipette tip grid  202  nested in the base  206 .  FIG. 10  is a cross-section through the grid  202  and base  206  along the line  10 - 10  and also through the cover  204  (absent from  FIG. 9  for clarity). An enlarged view of a portion of the cross-section of  FIG. 10  shows an exemplary embodiment of the lock mechanism  208  in  FIG. 11 . 
     It can be seen from  FIGS. 10 and 11  that the lock mechanism  208  is both external to the base  206  and to the cover  204 . Accordingly, the cover  204  does not have to be removed from the grid  202  in order to access the lock mechanism  208  as in the prior art. Thus, the entire grid assembly  210  can be advantageously detached from the base  206  while the cover  204  remains in place to protect the tops of the pipette tips  226 . 
     As noted,  FIG. 11  shows one exemplary lock mechanism  208  of the present invention, though the invention is not limited to this particular embodiment. The lock mechanism  208  includes a lever  300  that is configured to pivot around an attachment point  302  to the grid  202 . The attachment point  302  can be, for example, a segment of the flange  220  ( FIG. 7 ). A bottom portion  304  of the lever  300  includes a lip  306  that engages a corresponding recess  308  in the sidewall  214  of the base  206 . The recess  308  is shown in  FIG. 11  as an aperture through the sidewall  214 , but could also be a molded indentation, for example. It can be seen that when a top portion  310  of the lever  300  is pushed towards the cover  204 , the lip  306  disengages from the recess  308  in the sidewall  214  so that the grid  202  can detach from the base  206 . 
     In some embodiments of the invention, as shown in  FIG. 11 , the lock mechanism  208 , the grid  202 , and the attachment point  302  therebetween are integrally formed. In other embodiments, the attachment point  302  constitutes a device such as a hinge or spring that couples the lock mechanism  208  to the grid  202 . In either instance, the material or device at the attachment point  302  preferably has sufficient resiliency to return the lip  306  to a position where it will readily re-engage with the recess  308  when the grid  202  is returned to the base  206 . 
     Another embodiment of the invention is illustrated by  FIGS. 12-16 . In this embodiment a lock mechanism  400  of a grid  402  is configured to engage a base  404 , as shown in the cross-section of  FIG. 12 . An enlarged view of a portion of the cross-section of  FIG. 12  shows the lock mechanism  400  engaging the base  404  in greater detail in  FIG. 13 . Advantageously, lock mechanism  400  can also engage another grid  402  when the grids  402  are in an interlocked stacked arrangement as shown in the cross-section of  FIG. 14 .  FIG. 15  is an enlarged view of a portion of the cross-section of  FIG. 14  to show the lock mechanism  400  engaging the other grid  402  in greater detail. 
       FIG. 16  shows a perspective view of multiple grids  402  in the interlocked stacked arrangement between the base  404  and a cover  406 . It will be appreciated that because the lock mechanism  400  allows the grids  402  to interlock as shown, the interlocked stacked arrangement seen in  FIG. 16  cannot be accidentally separated during shipping and storage. The lock mechanism  400  also provides greater stability to the interlocked stacked arrangement so that a greater number of grids  402  can be stacked together. For instance, more than  5  grids  402  can be conveniently interlocked according to this embodiment. 
     In some embodiments, the base  206 ,  404 , the cover  204 ,  406  and the grid  202 ,  402  are manufactured from a material that is easy to form, that is relatively inexpensive, and that does not significantly outgas or shed particles. Plastic materials such as polypropylene work well. Glass filled polypropylene is a suitable material specifically for the grid  202 ,  402  as the glass filler provides additional stiffness. In some embodiments, the cover  204 ,  406  is made from a clear material to allow the pipette tips  226  to be readily seen without removing the cover  204 ,  406 . Injection molding is a suitable method for manufacturing these components. 
     In the foregoing specification, the invention is described with reference to specific embodiments thereof, but those skilled in the art will recognize that the invention is not limited thereto. Various features and aspects of the above-described invention may be used individually or jointly. Further, the invention can be utilized in any number of environments and applications beyond those described herein without departing from the broader spirit and scope of the specification. The specification and drawings are, accordingly, to be regarded as illustrative rather than restrictive. It will be recognized that the terms “comprising,” “including,” and “having,” as used herein, are specifically intended to be read as open-ended terms of art.