Ejection of individual microparticles from an electrified meniscus

On-demand production of 2D and 3D parts with complex geometries and/or high value material requirements is significant to many industries, and a broad goal of additive manufacturing. State-of-the-art methods for metal, ceramic, and advanced engineering materials typically utilize powder feedstocks, and the dimensional resolution of parts is limited to several particle diameters or larger, which limits precision applications. To address this challenge, we present a method to direct-write individual microparticles onto substrates using an electrohydrodynamic process. A liquid droplet, confined at an orifice and containing microparticles on its surface, is electrified, resulting in the dynamic ejection of individual microparticles from the droplet’s apex. We experimentally detail the electrohydrodynamic process of particle ejection and the parameter regime for which particles print individually. Scaling for ejection speed, liquid entrainment on the particle and satellite droplet formation are also discussed.