We present a novel dielectrophoretic technique that can be used to characterize molecular interactions inside a microfluidic device. Our approach allows functionalized beads which are initially at rest on a functionalized surface to be pulled away from the surface by the dielectrophoretic force acting on the beads. As a result, the interaction between the molecules on the surface and the beads can be quantitatively examined. We report detailed experimental results and validate the results with a model to show that the technique can be used to measure forces of interaction between molecules under various experimental conditions.