Particle based assays are rapidly gaining momentum in clinical diagnosis, food/airborne toxin detection and drug therapy and many other areas. Accurate characterization of interactions between bulk and Particle-surface necessitates the fundamental understanding of coupled fluid and bead motion (Fluid-Solid-Momentum Transfer). Wehave developed the models that fully integrate Lagrangian transport of the beads, convective-diffusive transport of species and bio-molecular surface binding reactions on the micro and macro particles.