Impact-induced generation of single airborne microspheres and the subsequent vacuum-driven assembly of ordered arrays

A myriad of wet assembly techniques exists to attain ordered arrays of micro- and nanoparticles. The present contribution proposes a universal and rapid (in order of a few seconds) dry assembly strategy that can be employed to assemble ordered arrays of particles with a designed spacing. This method involves shooting agglomerated monodisperse silica, polystyrene or PMMA powder microspheres with diameters ranging between 5–10 μm against an impact plating using pressure exceeding 2.5 bar. Consequently, the fluidized microspheres are attracted towards the pores of a silicon membrane device by applying a vacuum force. Furthermore, a brushing step is added to remove excess particles in undesired positions on top of the ordered arrays. An asset of the proposed method is that for the investigated particle properties, the same optimized conditions could be used to attain any desired 2-D particle arrangement that can be transferred on soft surfaces, e.g., PDMS.