On the Principles of Printing Sub‐micrometer 3D Structures from Dielectric‐Liquid‐Based Colloids

Dielectrophoresis‐assisted (DEP) on‐demand printing of dielectric‐liquid‐based colloidal gold under room conditions is demonstrated and employed to print 2D and 3D structures with sub‐micrometer feature sizes. The focus of the work is primarily on explaining the physics of the printing process, based on the formation of a controlled sequence of sub‐micrometer drops. The physics of 3D structure formation on the substrate is explained through the visualization and analysis of various time‐scales relevant to the printing process and the pinning of the contact line of the printed colloids. A parametric variation of the related variables, namely the applied voltage and the pulse length, is used to investigate the morphology and topography of a host of basic, printable 2D and 3D features. It is established that it is possible to obtain uniform particle deposits in 2D by filling up an initial coffee‐ring‐type non‐uniform deposit with a series of subsequently formed drops, all obtained during a single electric pulse. Finally, on‐demand production of multilayered, sub‐micrometer gold tracks is demonstrated, where the annealed tracks exhibit exceptionally low electrical resistivity for their sizes, only two times higher than that of bulk gold.