Pipettenspitze

摘要

A fractional-fill pipette assembly adapted to fill to a predetermined mark to obtain a desired known volume of liquid such as blood, plasma, test reagents or the like is disclosed. A means formed of a hydrophobic material is positioned within the tube bore, a predetermined distance from one end thereof so as to divide the capillary tube into two segments, one of the segments having a precise known volumetric capacity for collecting a desired known volume of liquid so that when the liquid fills the segment containing the precise known volume the liquid contacts the hydrophobic means defining the interface between the segments, the hydrophobic means breaks or resists the forces acting on the liquid filling the bore and prevents liquid from filling the pipette beyond the hydrophobic means by maintaining the surface tension of the liquid at the interface between the fluid and the hydrophobic means.