Field-Assisted Aerosol Jet Printing for Fabricating Flexible Electronics

The additive manufacture of production-grade flexible, large-area electronics is of intense interest in order to rapidly design, prototype, and fabricate electronics without reliance upon traditional electronics fabrication pathways (i.e. cleanroom processing). Such additive processes enable the direct integration of electronics on arbitrary, non-planar surfaces, expanding the potential form-factors and application spaces. Aerosol Jet Printing (AJP) is emerging as a powerful printing approach for high-resolution fabrication of printed high-quality electronic circuits, antennas, and sensors with design geometries not possible via other additive manufacturing technologies. AJP relies upon the controlled deposition of an aerosolized, liquid ink. Ink formulations typically utilize specialized material formulations (e.g. viscosity, particle fill volume) to adhere to deposition surfaces and maintain the prescribed print resolution. Here, we describe a new type of AJP print process that controls aerosol spatial position via acoustic field (‘acoustophoretic’) focusing for printing high-fidelity, high-resolution print lines. The acoustophoretic focusing relies upon differences in material properties between the ink and surrounding medium (air), rather than the material itself, enabling a “material agnostic” approach that is extensible to a broad array of established and nascent AJP ink chemistries. Acoustic forces offer the possibility to control the width of the printed material by focusing the aerosol jet to a narrower region than would be possible with a physical orifice. As the acoustic focusing effect is dependent on the ink droplet size, the utilization of acoustic focusing provides a means to “refine” the jet (especially if not material rich) such that the deposited material has a smaller line width and exhibits a reduction in the typically observed particle overspray.