The present invention is directed to emitting biofluids from drop ejection units, and more particularly to priming mechanisms used to obtain proper drop ejection sensing and controlling the level of biofluid within drop ejection devices.
Various designs have been proposed for the ejection of biofluids which permit the high-speed printing of sequences and arrays of drops of biofluids to be used in various tests and experiments. In the present discussion, a biofluid, also called a reagent, may be any substance used in a chemical reaction to detect, measure, examine or produce other substances, or is the substance which is to be detected, measured, or examined.
Biofluid ejection devices find particular utility in the depositing of drops on to a substrate in the form of a biological assay. For example, in current biological testing for genetic defects and other biochemical aberrations, thousands of the individual biofluids are placed on a glass substrate at different well-defined locations. Thereafter, additional depositing fluids may be deposited on the same locations. This printed biological assay is then scanned with a laser in order to observe changes in the biofluid property.
It is critical in these situations that the drop ejection device not be a source of contamination or permit unintended cross-contamination between different biofluids. Also, due to the high cost of these biofluids, and the importance of positioning properly formed drops at highly precise locations, it is important that the drop ejectors operate correctly at the start of the drop ejection process.
In view of the foregoing, it has been considered desirable to provide priming mechanisms which ensure the proper delivery of biofluids to an ejector device in a timely, useful manner.