Patent ID: 7642058

Claim:
A method of characterizing an interaction between at least two species, comprising: providing a measurement system comprising a sensor device comprising a flow cell having at least one species immobilized to a surface thereof; providing a liquid sample volume containing at least one species capable of interacting with the immobilized species; passing the liquid sample volume through the flow cell to contact the species in the sample volume with the immobilized species; and detecting by the sensor device a result of an interaction of species in the sample volume with immobilized species; the improvement comprising: aspirating into a line of the measurement system the sample volume adjacent to a volume of a liquid devoid of the at least one species, so that the two liquid volumes mix by dispersion to generate a liquid volume containing a concentration gradient of the at least one species, intersecting the liquid volume containing the concentration gradient at least five times with at least one additional liquid devoid of the at least one species to thereby create a liquid flow comprising alternating volume segments of (i) the liquid comprising the concentration gradient and (ii) the at least one additional liquid, so that a plurality of segments of liquid including different concentrations of the species forming the concentration gradient separated by segments of at least one additional liquid are obtained; and detecting by the sensor device for each liquid segment the result of an interaction with immobilized species or interacted immobilized species, whereby interactions for a plurality of different concentrations of the at least one species are detected.