Patent ID: 8206988

Claim:
A flow cytometry apparatus nozzle to sort sperm cells in a fluid stream by chromosome content comprising: a. a nozzle body having a fluid stream entry portion and a fluid stream exit portion and an interior surface separating both portions along which a fluid stream flows when operating to sort sperm cells; b. the interior surface of the nozzle comprising: a first axially tapered region having a first angle of taper; a second axially tapered region having a second angle of taper, the second axially tapered region adjacent to and downstream of the first axially tapered region; and a third axially tapered region having a third angle of taper, the third axially tapered region adjacent to and downstream of the second axially tapered region, wherein the angle of taper of the second axially tapered region is different than the angle of taper of the first and third axially tapered regions, and wherein at least two of the axially tapered regions have generally elliptical cross sectional shapes oriented in different directions for applying torsional forces to the fluid stream passing there through, the torsional forces tending to bring sperm cells in the stream into a desired orientation.