Patent ID: 8241883

Claim:
A method of detecting an interaction between a first molecule and at least a second molecule in a microfluidic device, the method comprising: flowing a first labeled molecule with a first electrophoretic mobility through at least a first microchannel, wherein flowing of the first molecule comprises a continuous injection of the first molecule; flowing at least a second molecule with a second electrophoretic mobility through the microchannel, wherein flowing of the second molecule comprises an intermittent injection of the second molecule at a first frequency; applying a pulsed electric field through the microchannel, wherein the pulsed electric field separates the first and at least second molecule based upon the electrophoretic mobilities of the molecules; adjusting the pressure induced velocity or electrokinetic mobility of the two molecules to optimize a measurement of assay sensitivity by maximizing a value of ΔC I /C o , wherein ΔC 1 is the difference in concentration of the two molecules when the pulsed field is on and C o is the concentration of one of the molecules when the pulsed field is off; and detecting a level of label or a level of signal from a label in the microchannel over a select time period.