INSTRUMENT FOR SELECTING AND DEPOSITING MULTICELLULAR ORGANISMS AND OTHER LARGE OBJECTS

摘要

An instrument for analyzing and dispensing objects larger than about 70.mu.m in diameter is based on a flow cytometer with a novel fluidic switch arrangement for diverting a portion of a sample stream in response to detect or signals in a flow cell. The instrument is particularly adapted for dispensin g multicellular test organisms like nematodes or large microspheres for use in screening large libraries of potential pharmaceutical agents. Hydrodynamic focussing is used to center and align the objects in the flow cell. The objects pass through a sensing zone where optical or other characteristics o f the objects are detected. The detector signals are processed and used to operate a fluidic switch that is located downstream from the sensing zone. T he fluid stream containing the detected objects emerges from the flow cell into air where a fluid stream controlled by the fluidic switch diverts portions o f the stream containing no sample objects or sample objects not meeting predetermined characteristics. The undiverted sample stream deposits selecte d sample objects into a plurality of containers.