On the electrohydrodynamic jet printing of two-dimensional material-based inks for printed electronics

Electrohydrodynamic (EHD) jet printing is a well-known advanced manufacturing technique that uses electric fields to generate and control fine jets of fluid for high-precision deposition of materials. This method enables the printing of extremely fine features, making it ideal for applications such as printed electronics. However, little is known about the optimal conditions for achieving consistent jet stability and droplet formation, especially when dealing with complex and volatile fluids laden with two-dimensional (2D) nanoparticles. In this work, we study the electrohydrodynamic printing process of 2D material-based inks using toluene as the main carrier fluid. Adding ethyl cellulose to toluene allows us to increase the stability of the suspensions and establish the steady cone-jet mode of electrospray. A small amount of ethanol increases the fluid conductivity, stabilizing the steady cone-jet mode and reducing the jet diameter. The inks behave as leaky-dielectric, weakly viscoelastic liquids. For this reason, the jet diameter and minimum flow rate obey the scaling laws for electrospray of Newtonian liquids. We determine the optimal parameter conditions for the EHD printing of our inks directly onto a non-conductive substrate. The influence of the substrate's velocity on the width of the printed lines is analyzed. These findings enlarge the knowledge about how to increase the throughput in the EHD jet printing process while controlling the resolution of the printed lines when using volatile solvents, 2D nanomaterials, and non-conductive substrates.