We report systematic experimental and computational studies to analyze evaporative self-assembly of micro particles in printed picoliter suspension droplets. Evaporative self-assembly of micro particles in picoliter droplets is enabled by a droplet-printing system for small-scale particle suspension droplets. Experiments were performed to study the regime where particle interactive forces become comparable to hydrodynamic, evaporative forces of an evaporating droplet. A particle-based computational method was developed to calculate the particle-to-particle clustering time. In this study, we verify that there is a time-scale competition between particle-to-particle clustering and evaporation of the liquid medium that determines the final morphology of micro particle assemblies. (C) 2013 Elsevier B.V. All rights reserved.