Conducting chemical reactions and using chemical reactions with a further measurement step in an assay is a practice widely used in biological, pharmaceutical, and chemical research as well as in vitro diagnostics. Billions of reactions and assays are performed annually. In a chemical reaction, two or more fluidic components are reacted to produce at least a third component. A fluidic component may be a reagent, such as a sample or a chemical. In an assay test, a chemical reaction among two or more fluidic components is used to determine any resulting activity, such as a concentration. Modern biological and pharmaceutical research frequently includes numerous assays for specific biological activities in cells or isolated biochemicals in order to discover novel biological targets for disease, new medicines directed to those targets, biological indications of a diseased or healthy condition, or other chemicals valuable in the agrochemical, foodstuffs, cosmetics, and other industries.
In drug discovery, for example, a sizeable number of assays (up to 1.5 million experiments per day in a single laboratory, for example) are prepared by combining two or more components. The assays may each contain a sample of a distinctive, unique chemical compound. These samples are tested to determine if any of the compounds they contain exert an effect or particular biological activity. Promising compounds are identified for further pursuit as potential therapeutic agents.
The fluidic components of the assay sample can be very expensive, unique, dangerous and/or in very limited supply. For efficiency and higher throughput, substantial attention has been devoted to reducing the sample volume of assays while advancing the ability of assays to discriminate small changes in biological activity. The combination and manipulation of these fluidic components rely on extreme accuracy and precision in dispensing small volumes of these fluids into reaction wells.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.