Functionally versatile cassettes

#An “assay run” is an investigative or analytic event used in, for example, laboratory medicine, pharmacology, analytical chemistry, environmental biology, or molecular biology, for qualitatively assessing or quantitatively measuring the presence, amount, or the functional activity of a sample. The sample may be a drug, a genomic sample, a proteomic sample, a biochemical substance, a cell in an organism, an organic sample, or other inorganic and organic chemical samples. An assay run may measure an intensive property of the sample and express it in the relevant measurement unit such as, for example, molarity, density, functional activity in enzyme international units, degree of some effect in comparison to a standard, among other measurable characteristics. An assay may involve reacting a sample with a number of reagents, and may be classified as an instance of an assay procedure conforming to an assay protocol. An assay protocol may involve a set of reagent and/or sample fluids being dispensed in specific amounts to a number of assay reaction sites such as wells within an assay plate. Further, an assay protocol may include additional processing such as mixing, separation, heating or cooling, incubation, and eventually at least one read-out. The reproducibility and run-to-run comparability of an assay depends on the reproduction of its protocol.

#The accompanying drawings illustrate various examples of the principles described herein and are a part of the specification. The illustrated examples are given merely for illustration, and do not limit the scope of the claims.

#FIG. 1 is a block diagram of a fluid ejection device according to an example of the principles described herein.

#FIG. 2 is a block diagram of a system for ejecting a fluid into an assay according to an example according to an example of the principles described herein.

#Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.

#Assay runs as described above have been done by hand using, for example a pipette. In order to complete the assay, a user may selectively take a sample using the pipette and eject a metered amount of the sample into individual wells of an assay plate. This is all done by hand and has proven to be time consuming. Additionally, because a human is ejecting the samples into the individual wells of the assay plate, mistakes may be made and an extra amount of the sample may be added to any particular well or a portion of sample may not be added at all.

#To place user interaction to a minimum, automated assay fluid dispensing systems have been developed that may dispense assay fluids, e.g., samples and reagents, in a precise, controlled fashion to multiple reaction sites within an assay plate in a short time. For example, a carefully formulated mixture of several reagents, including a target species of interest, may be carefully formulated at multiple reaction sites for the testing of a set of test sample reagents at multiple concentrations. This allows many reactions to proceed contemporaneously. The automation reduces user effort and user-caused variability, while the concurrency further reduces the time to complete a complex assay.