In situ-dilution method and system for measuring molecular and chemical interactions

A method for testing multiple analyte concentrations within a biosensor system comprising the steps of:

• passing a first fluid through a first flow path at a first fluid flow rate, said first fluid including a first concentration of analyte;
• passing a second fluid through a second flow path at a second fluid flow rate, said second fluid free of the analyte;
• merging the first and second fluids from said first and second flow paths into a third flow path to form a third fluid, said third fluid having a second concentration of analyte;
• passing said third fluid through said third flow path at a third fluid flow rate to a sensing region;
• and
• continuing the flow of said first, second and third fluids without interruption while adjusting the concentration of said analyte in said third fluid by adjusting the first and second fluid flow rates at least once thereby exposing the sensing region to at least one additional concentration of analyte in said third fluid different from said second concentration of analyte.