Patent ID: 6197259
Filing Date: 2001-03-06
Classification: B01L

Abstract:
An improved pippette device comprising a plastic pipette tip mountable on and ejectable from a pipette tip mounting shaft by application of axial mounting and ejection forces of less than three pounds:the pipette tip mounting shaft comprising:a distal end portion including an axially inwardly tapering sealing zone and a diameter ""x"" at its distal end; andthe pipette tip comprising:a tubular proximal portion comprising (i) a frusto conical open top portion having an inner diameter greater than ""x"" at its upper open end for axially receiving the distal end of the mounting shaft and having a sidewall tapering downwardly and axially inwardly at an angle greater than the axial taper of the mounting shaft so that the distal end of the mounting shaft will engage a lower open end of the open top portion prior to the inwardly tapering sealing zone engaging the sidewall of the open top portion, (ii) a hollow mid-portion having a substantially cylindrical sidewall extending from the lower open end of the sidewall of the open top portion and (iii) an annular sealing region comprising an inwardly facing annular line seal formed by a junction of the sidewalls of the downwardly and inwardly tapering open top portion and the substantially cylindrical mid-portion and having an inner diameter less than x so as to engage the distal end of the sealing zone of the mounting shaft as the mounting shaft is inserted into the proximal portion of the pipette tip, the sidewalls of the open top and mid-portions in the annular sealing region being sufficiently thin that the annular line seal will expand and form a fluid tight seal with the sealing zone of the mounting shaft as the sealing zone penetrates the sealing region;a tubular distal portion extending from the mid-portion and terminating in a distal end opening for passing fluid into and from the tip upon operation of the pipette device; andcircumferentially spaced lateral stabilizing contacts extending from an inside surface of the sidewall of the pipette tip adjacent the sealing region and defining regions on a cylinder having an inner diameter equal to or less than ""x"" and the sidewall of the pipette tip from which the contacts extend being sufficiency thin to deform between the contacts as the contacts engage an outer surface of the mounting shaft as it is inserted into pipette tip to laterally stabilize the tip on the shaft.