Abstract:
A centrifuge comprising a zonal rotor, a centrifuge chamber having a side wall and a bottom wall to contain the zonal rotor, an upper shield to cover the top of the centrifuge chamber and enclose the zonal rotor, and an annulus in the centrifuge chamber that is laterally spaced apart from the zonal rotor. The annulus has a channel with a base and a lip, where the channel has an open end facing the direction of the upper shield to collect liquid sample leaked during loading or unloading the zonal rotor.

Description:
RELATED APPLICATION 
     This application claims benefit of priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 61/028,301 filed on Feb. 13, 2008, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention pertains generally to a liquid sample collection device for use in the process of zonal centrifugation. The device captures liquid sample that may spill or leak during the process of loading or unloading liquid sample while the rotor is spinning. This prevents the leaked liquid sample from coming into contact with sensitive components inside the centrifuge chamber, thereby protecting the centrifuge from damage. 
     In the process of zonal centrifugation, the centrifuge rotor is loaded and unloaded with liquid sample while the rotor is spinning. During the loading and unloading of liquid sample, it is difficult to maintain a complete, tight seal between the spinning rotor and the stationary sample-loading apparatus. Consequently, some of the liquid sample may leak into the centrifuge chamber during the loading or unloading of the zonal rotor. The centrifugal force of the spinning rotor tends to propel this leaked liquid outward towards the wall of the centrifuge chamber. This leaked liquid may then flow down the wall of the centrifuge and settle on the bottom of the centrifuge chamber where it may come into contact with sensitive electronic or mechanical components of the centrifuge causing damage to the centrifuge. 
     It is therefore desirable to prevent damage to a centrifuge caused by exposure to liquid sample that leaks into the centrifuge chamber during the loading and unloading of a rotor during zonal centrifugation. The present invention provides a liquid sample collection device that captures this leaked liquid, thereby preventing damage to the centrifuge. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a liquid sample collection device that captures leaked liquid sample during the process of loading or unloading of a zonal rotor. The top of the device supports the liquid sample fill head of the zonal rotor. The top and side interior walls of the device provide containment for leaked liquid sample that is propelled outward due to centrifugal force of the spinning rotor. A lip at the bottom of the device forms a channel to collect the liquid sample that flows down the walls of the device. The sample collection device is removed from the centrifuge after loading or unloading of the zonal rotor, thereby removing the leaked liquid sample from the chamber and preventing the leaked liquid sample from coming into contact with sensitive components inside the centrifuge chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a liquid sample collection device in accordance with the present invention arranged in a centrifuge. 
         FIG. 2  illustrates a top view of a liquid sample collection device in accordance with the present invention. 
         FIG. 3  illustrates an isometric view of an upper shield and an annulus in accordance with the present invention. 
         FIG. 4  illustrates a top view of an annulus in accordance with the present invention. 
         FIG. 5  illustrates a front view of an annulus in accordance with the present invention. 
         FIG. 6  illustrates a right side view of an annulus in accordance with the present invention. 
         FIG. 7  illustrates a bottom view of an annulus in accordance with the present invention. 
         FIG. 8  illustrates a section view of an annulus in accordance with the present invention. 
         FIG. 9  illustrates an isometric view of an annulus in accordance with the present invention. 
         FIG. 10  illustrates a section view of an annulus in accordance with the present invention. 
         FIG. 11  illustrates a liquid sample collection device in accordance with the present invention arranged in a centrifuge. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides a device for capturing liquid sample that leaks during the loading or unloading of a zonal rotor. The device prevents leaked liquid sample from collecting on the walls of the centrifuge chamber and from coming into contact with sensitive electrical or mechanical components inside the centrifuge. An advantage is the prevention of damage to the centrifuge that may arise due to contact of the leaked liquid sample with sensitive components inside the centrifuge. Another advantage is the prevention of liquid accumulation on the walls of the centrifuge chamber that may interfere with obtaining the proper vacuum inside the chamber during centrifugation. 
     DEFINITIONS 
     A liquid sample fill head is a fixture including ball bearing and rotating/stationary seal that is used to load and unload sample into/out-of a spinning zonal rotor. 
     A zonal rotor is a centrifuge rotor that can be loaded and unloaded with sample while spinning for the process of zonal centrifugation. 
     Loading of a zonal rotor means adding sample to a zonal rotor while the rotor is spinning at a rotor loading speed. 
     Unloading of a zonal rotor means removing sample from a zonal rotor while the rotor is spinning at a rotor unloading speed. 
       FIG. 1  illustrates a liquid sample collection device  10 , an embodiment of the present invention, arranged in a centrifuge  12 . The arrangement includes the liquid sample collection device  10  disposed about a zonal rotor  14  and a liquid sample fill head  16  inside a centrifuge chamber  18 . A support band  22 , which may be a metal ring, is located on the inside of the centrifuge chamber  18  to position the liquid sample collection device  10  at the correct location relative to the zonal rotor  14 . In the illustrated embodiment, tabs  21  project outward from generally the top outer edge of the liquid sample collection device  10 , and corresponding slots  25  are located on the support band  22 . The tabs  21  fit into the slots  25  to position and hold the liquid sample collection device  10  at the correct location relative to the zonal rotor  14 . The tabs  21  may be retractable to facilitate the insertion of the tabs  21  into the slots  25 . Although the embodiment depicted in  FIG. 1  discloses a metal support band  22  with slots  25 , the support band  22  can be any suitable structure for holding and positioning the liquid sample collection device  10 . The liquid sample fill head  16  may be installed onto the liquid sample collection device  10  for the loading and unloading of the zonal rotor  14  with liquid sample while the zonal rotor  14  is spinning. 
     In a preferred embodiment, the liquid sample collection device  10  includes an upper shield  24 , a vertical wall  26 , a base  28 , and a lip  32 . In the illustrated embodiment, the upper shield  24  is a circular plate with a central hole  34 . The central hole  34  facilitates the liquid sample fill head  16  to attach to the zonal rotor  14  or to hold the liquid sample fill head  16  during the loading and unloading process. A bracket  33  with opposed fingers  37  is attached to the top of the upper shield  24  and is centered over the central hole  34 . Locking grooves  17  are formed in opposite sides of the liquid sample fill head  16 . The locking grooves  17  engage the opposed fingers  37  to install and reversibly lock the liquid sample fill head  16  into position on the upper shield  24  for loading and unloading the zonal rotor  14 . 
     The vertical wall  26  is generally a cylinder that extends downward from about the outer radial edge of the upper shield  24 . The base  28  depends toward the zonal rotor  14  and the lip  32  extends vertically from the base  28 . Arranged this way, the vertical wall  26 , base  28  and lip  32  form a channel  36  where liquid sample that leaks from the liquid sample fill head  16  during loading or unloading of the zonal rotor  14  is contained by the upper shield  24  and the vertical wall  26 , and is collected in the channel  36 . The upper shield  24  prevents leaked sample from being expelled upward out of the centrifuge, while the vertical wall  26  contains and captures leaked sample that is propelled outward by the centrifugal force of the spinning rotor  14 . Contained liquid sample that flows down the vertical wall  26  collects in the channel  36 . The containment of leaked liquid sample by the upper shield  24  and the vertical wall  26 , and the collection of leaked liquid sample by the channel  36  prevents leaked liquid sample from accumulating inside the chamber  18  of the centrifuge  12 . In the absence of such a containment and collection device, leaked liquid sample may come into contact with instrument electronics located underneath the refrigeration can, or with the centrifuge drive, resulting in component or drive failure. 
     In one embodiment, the upper shield  24 , the vertical wall  26 , the base  28  and the lip  32  are made from plastic. However, these parts may be made from any suitable material. 
     Also, in a preferred embodiment, the vertical wall  26 , the base  28  and the lip  32  are molded as a one piece annulus  38 . 
     In another embodiment, the vertical wall  26  is composed essentially of a stack of multiple cylindrical pieces. 
     After loading the zonal rotor  14  with sample, the liquid sample collection device  10  can be removed from the centrifuge  12  by disengaging the tabs  21  from the slots  25  and lifting the liquid sample collection device  10  off of the support band  22 , thereby removing the collected leaked liquid sample from the centrifuge  12  before a vacuum is applied to the centrifuge chamber  18 , the rotor is spun at a rotor centrifugation speed, and the centrifugation run is completed. An advantage is that the liquid sample collection device  10 , being removable, does not interfere with temperature control during centrifugation. Likewise, the liquid sample collection device  10  can be removed after unloading the zonal rotor  14 , thereby removing the collected leaked liquid sample from the centrifuge  12 . The rotor centrifugation speed may be greater than the rotor loading speed. 
     In a preferred embodiment, a drain hole  42  is formed in the base  28  ( FIG. 10 ). A plug  44  reversibly seals the drain hole  42  to provide for the removal of collected fluid from the liquid sample collection device  10  after the liquid sample collection device  10  has been removed from the centrifuge  12 . 
     In another preferred embodiment, a piloting feature  46  extends outward from the upper circumference of the upper shield  24  ( FIG. 11 ). The piloting feature  46  facilitates the installation and the positioning of the liquid sample collection device  10  in the centrifuge chamber  18  by guiding the liquid sample collection device  10  in essentially straight upwards or straight downwards movement when the liquid sample collection device is installed into or removed from the centrifuge chamber  18 , thereby avoiding contact of the liquid sample collection device  10  with the spinning zonal rotor  14 . 
     In another preferred embodiment, the liquid sample collection device  10  includes a projection  52  extending generally outwards from the top of the lip  32  towards the vertical wall  26  ( FIG. 10 ). The projection  52  serves to narrow the opening to the channel  36 , thereby reducing the chance of spilling liquid sample out of the channel  36  when the liquid sample collection device  10  is removed from the centrifuge  12 .