Abstract: A droplet travel path monitoring mechanism for a flow cytometer is operative to adjust the droplet break-off point back to an initially calibrated spatial location, in the event of the departure from calibrated timing of gaps in the unsorted fluid droplet stream that have been created by the deflection of charged droplets. In addition, the flow cytometer is operative to monitor prescribed characteristics of deflected droplet streams, and to controllably adjust drop-sorting deflection parameters, so as to maintain the deflected travel path of sorted droplets coincident with the opening into a sorted droplet collection container, thereby maximizing collection of all sorted droplets.

Abstract: Automatic biological sample mixing apparatus for use in flow cytometry, wherein a sample container is secured loosely at its top by means of a multi-reagent dispensing head; and the container is mounted at its bottom on a resilient support disposed on an elliptically rotated member, to cause reagents introduced into the container to be thoroughly mixed with a sample in the container in a fast, efficient, gentle, and accurately repeatable manner.