Electrohydrodynamic (EHD) ink-jet printing has been actively researched as a means of refining ink-jet printing. Currently, most of the research on this topic has centralized on the development of the printing process and optimization, while few studies have focused on the relationships between printing materials properties and printed patterns performance.

In this study, silver and tungsten-based particle-solvent dispersed inks were formulated capable of EHD printing. Several formulations were made to explore key variances in their performance. More generally, a methodology was developed to characterized and evaluate ink printability using materials properties. It identified a critical relationship between the formulation and fluid properties, which affects the printing results and functional performance. Also, particle size was studied and it was shown that it can drastically impact droplet image behaviors. In order to capture and analyze these phenomena, machine vision was utilized, assisting capture high-speed images to characterize droplet shape and timely response.

In the silver-based ink formulation study, our data reveals that under identical printing conditions, the size of the printed features is a function of ink fluid viscosity, surface tension, and dielectric constant. Within the same formulation, the size of the printed features is a function of amplitude, frequency, and duty ratio of the alternating current (AC) square wave voltage signal. In our tungsten ink study, the droplet impact behaviors on glass substrates, including impact reaction time, droplet height, diameter, and dynamic contact angle, are functions of particle size of tungsten nanoparticle used in the ink formulation.

With the discovery of relationships at hand, optimal formulations were proposed for inks used in the EHD printing regarding printing resolution and stabilization. The x-ray shielding efficiency was also evaluated on the differences between bulk tungsten and nanoparticle ink multilayer printed tungsten. Data suggested that with the increase of the numbers of layers printed, the shielding efficiency increases indicating an improved, denser nanoparticle packing condition. Finally, future research directions were proposed, including further improving printing resolution, improved nanoparticle packing density and 3D printability.