Structure formation in suspensions of microparticles from coffee-ring to blood clot are determined by local physical forces, hydrodynamic instabilities and phase transitions. The coffee-ring effect in drying droplets was explained by non-uniform curvature-dependent evaporation of liquids, capillary flow and Marangoni flow of the particles, their diffusion, sedimentation, vertical mixing, viscous stresses, and DLVO forces. In the talk, a brief review of different structures formed in the drops or thin films of suspensions will be given, and the corresponding mathematical models will be discussed. Novel statistical results on the solid depositions at different scales will be presented. The observed structures are very promising for digital microfluidics and other applications.