Apparatuses and methods for stable aerosol-based printing using an internal pneumatic shutter

Abstract

The object of the invention is the provision of apparatuses and methods for stable direct printing of continuous films or discreet structures on a substrate using an internal pneumatic shutter. The invention uses an aerodynamic focusing technique, with a print head comprising an aerosolization source, a flow cell, an aerodynamic lens system, and a pneumatic shutter assembly. The method uses an interchangeable and variable aerodynamic lens system mounted in the flow cell, and an annularly flowing sheath gas to produce a highly collimated micrometer-size stream of aerosolized droplets. The lens system is comprised of a single-orifice or multi-orifice lens coupled to a converging fluid dispense nozzle. A liquid atomizer with temperature control is used to produce an aerosol size distribution that overlaps the functional range of the aerodynamic lens system. The shutter assembly can be attached directly to the print head, or mounted external to the print head in a control module. The preferred embodiment of the invention contains no moving parts internal to the print head, and provides non-contact shuttering of an aerosol stream. Internal shuttering of the aerosol stream is accomplished using co-propagating compressed gas and vacuum flows, a single vacuum exhaust flow, or by redirecting an aerosol carrier gas from the input port of an aerosol chamber to a continuously propagating sheath gas flow. The apparatus uses no external parts to collect or redirect the aerosol stream outside the print head. The internal shutter design allows for a reduced printer working distance, so that a substrate may be placed at the focal point of small aerosol droplets focused near the print head exit nozzle. The method produces well-defined traces on a substrate with line widths in a range from approximately 10 to 1000 microns, with sub-micron edge definition and shuttering times as small as 10 milliseconds.