Pipette and sealing tip

Abstract

A sealing pipette tip includes features to seal the tip directly against the piston in an air displacement pipette, avoiding the need for a piston seal within the pipette. This configuration reduces potential points of failure, allows the pipette-tip interface to be optimized, and improves liquid handling characteristics of the pipette.

1 . A pipette tip for use with an air displacement pipette that includes a tip mounting shaft and a piston mounted for axial movement within the shaft, the shaft having a distal end and an interior surface, and the interior surface defining an interior space around the piston, the tip having a generally elongated tubular configuration and comprising:
 a mount portion including an open proximal end and an inward-facing sealing region; and   a liquid handling portion including a tapered open distal end;   wherein the mount portion is adapted for sliding insertion into the distal end of the shaft; and   wherein, when the pipette tip is mounted on the shaft, the mount portion of the pipette tip extends into the interior space between the piston and the interior surface of the shaft, the piston penetrates the open proximal end of the pipette tip and is axially movable within the mount portion of the tip, the sealing region of the pipette tip forms an air tight seal against the piston, and an air volume is maintained between a distal face of the piston and any liquid in the pipette tip, the axial movement of the piston causing the liquid to be displaced.   
     
     
         2 . The pipette tip of  claim 1 , wherein the inward-facing sealing region comprises a projecting sealing ring. 
     
     
         3 . The pipette tip of  claim 5 , wherein the sealing ring is adapted to be compressed against the piston by the tip mounting shaft when the tip is mounted on the shaft. 
     
     
         4 . The pipette tip of  claim 2 , wherein the sealing ring has a diameter smaller than the diameter of the piston when the tip is not mounted on the shaft. 
     
     
         5 . The pipette tip of  claim 2 , wherein the sealing ring has an uncompressed diameter approximately equal to or larger than the diameter of the piston when the tip is not mounted on the shaft. 
     
     
         6 . The pipette tip of  claim 1 , further comprising structure of the pipette tip cooperative with structure of the pipette shaft for preventing the tip from moving axially with respect to the pipette when the piston is moved through the air tight seal. 
     
     
         7 . The pipette tip of  claim 1 , further comprising structure of the pipette tip cooperative with structure of the pipette shaft for limiting the axial travel of the tip on the shaft to insure uniform depth of mounting shaft penetration into the pipette tip. 
     
     
         8 . The pipette tip of  claim 7 , wherein the structure of the pipette tip comprises a recess defined by the tip and adapted to mate with a corresponding projection on the shaft, or a projection on the tip adapted to mate with a corresponding recess defined by the shaft. 
     
     
         9 - 21 . (canceled)