Self-assembly of polystyrene microspheres within spatially confined rectangular microgrooves

A convective self-assembly of mono-sized polystyrene spheres with diameters ranging from 262 to 1000 nm was conducted on patterned silicon wafers with one-dimensional, periodic rectangular microgrooves of different widths (0.65–6 lm). The latex beads were driven into the spatially confined microgrooves by the capillary interactions and the confined wall during solvent evaporation, resulting in a range of packing structures. Processing variables including evaporation temperature, particle size (D), groove width (W), and groove height (H) were examined experimentally, and geometrical models were proposed to explain the various packing structures obtained. The degree of spatial freedom for the particles to rearrange themselves in the confined channels is found critical to the assembled particle-packing structure.