Electrostatic Control of Extruded Ink Drops and Jets for Nozzle-Based 3D Printing Applications*

Nozzle-based three-dimensional (3D) printing technologies, which build a model by depositing materials layer-by-layer, are handicapped by low throughput and different geometric restrictions, which limit where the nozzle can print and how sensitive the prints are to distortions. Here, we introduce additional electrode/s of different configurations, to the printhead, generating an electric field between added electrode/s and printing nozzle. The resulting Coulomb forces manipulate the extruded ink facilitating desirable improvements of the printing process (e.g., higher translational speeds, thinner trace widths, improved deposition on rough surfaces, pre-charge low-volume droplets for enhanced placement, and creation of trace lines and films from discrete drops via electrocoalescence).  Using the predictions of the electrohydrodynamic theory of Direct Ink Writing (DIW) processes proposed in this work, electrode configurations were retrofitted to both a DIW/Drop-on-Demand printer. This relatively simple integration of the electrode to the printhead allowed successful prints with characteristics not found elsewhere. The ability to precisely manipulate extruded materials is essential in additive manufacturing and these results divulge a plethora of design opportunities and ink control in 3D printing processes.