Lay summary
This project is a fundamental investigation of a novel, capillarity-related, maskless method for the non-contact deposition of nanoparticle colloids leading to the generation of 2D and 3D functional submicron structures at room conditions. State of the art non-contact direct writing is realized by ink-jet printers, but limited to feature sizes of several micrometers. A further downsizing of this technology has proven to be difficult and prohibitingly high pressure is required to mechanically eject droplets by piezoelectric or thermal actuation.Using our novel electro-hydrodynamic approach, submicron printing out of capillary openings is feasible and has already been demonstrated to yield functional micro and nanostructures as much as two orders of magnitude slammer that the several micron features printed by inkjet technologies. In contrast to existing technologies, this novel mechanism allows for the deposition of not only 2D but also of 3D structures (nanowires) well into the submicron range. Since the physical mechanisms of the colloidal microdroplet generation out of capillary openings and its control are not fully understood, a detailed investigation of the physical processes involved includes aspects of submicron scale fluid dynamics, electrohydrodynamics of colloids, wetting phenomena, and rapid vaporization processes.In addition to the theoretical approach, a detailed experimental study will cover a wide parametric domain of wall materials, cavity geometries, colloid properties and electrostatic field aspects, thus creating a science base for this technology. Reducing the feature size by printing out of nozzle openings as small as O(100) nm is part of the envisioned results as well as the investigation of the thermal processing of exemplary functional structures obtained with the methods, in particular for metallic and semiconducting nanoparticle materials. Printing on curved surfaces as a special feature of the novel deposition process will be an additional subject of investigation.