Investigation of surface charging dynamics and effects on ink jetting behaviors for plasma-induced electrohydrodynamic printing

The rapid evolution of conformal electronics necessitates advancements in high-resolution printing on three-dimensional curved insulating surfaces directly. A recently developed technique, known as plasma-induced electrohydrodynamic (PiE) printing, is a promising technique that enables micron and submicron scale printing on arbitrary dielectric substrates. However, factors that govern the deposited charges and the effects of the constructed electric field on induced jetting behavior have not been fully comprehended. Here, we investigate the role of plasma-surface interaction in PiE printing and its impact on the printing process. The local electric field, constructed by site-selective deposition of positive charges on the dielectric surfaces through plasma jet impingement, forms a spatial region of effective influence. The geometrical and electrical parameters of the PiE printing system significantly influence the spreading range and intensity of plasma on the surface and hence the effective region, and therefore determines the induced ink jetting behavior and the jets/droplets traction and deflection. Our study reveals the relationship between the plasma jet and inkjet dynamics in PiE printing, providing insights into the interplay between the plasma spreading behavior and process parameters. The optimization of these parameters can enable better performance of high-quality PiE printing.