An Automated Device for Aseptically Aspirating Serum From Blood Collection Tubes

A new device for aspirating serum from blood collection tubes following centrifugation is described and details of its design and construction are presented. Unlike current laboratory practice, the device operates aseptically, without exposing the operator to potentially infectious samples. The device automatically locates the top of a collection tube of any standard size, penetrates the stopper, and extends a level-sensing probe into the interior of the collection tube. A sensor at the distal end of the probe detects the interface between the serum and the cell coagulum or silicone barrier in collection tubes that employ an internmediate density barrier to separate the serum from the cell coagulum upon centrifugation. Extension of the probe into the sample is precisely controlled, irrespective of the level of the interface, to ensure that the aspirator openings in the probe are always positioned above the interface and entirely within the serum, yet sufficiently close to the interface to ensure that substantially all of the serum is collected. A particulate-free serum is obtained by minimizing disturbance of the cell coagulum.