Inkjet printing on hydrophobic surfaces: Controlled pattern formation using sequential drying

Inkjet-printed micro-patterns on hydrophobic surfaces have promising applications in the fabrication of microscale devices such as organic thin-film transistors. The low wettability of the surface prevents the inkjet-printed droplets from spreading, connecting to each other, and forming a pattern. Consequently, it is challenging to form micro-patterns on surfaces with low wettability. Here, we propose a sequential printing and drying method to form micro-patterns and control their shape. The first set of droplets is inkjet-printed at a certain spacing and dried. The second set of droplets is printed between these dry anchors on the surface with low wettability. As a result, a stable bridge on the surface with low wettability forms. This printing method is extended to more complicated shapes such as triangles. By implementing an energy minimization technique, a simple model was devised to predict the shape of the inkjet-printed micro-patterns while confirming that their equilibrium shape is mainly governed by surface tension forces. The gradient descent method was utilized with parametric boundaries to emulate droplet pinning and wettability of the anchors and to prevent convergence issues from occurring in the simulations. Finally, the energy minimization based simulations were used to predict the required ink to produce dry lines and triangles with smooth edges.

Automated summary

Inkjet-printed micro-patterns on hydrophobic surfaces have potential applications in microscale device fabrication. A sequential printing and drying method was proposed to form micro-patterns and control their shape, overcoming the challenge of low wettability. An energy minimization technique and gradient descent method were utilized to predict and simulate the shape of inkjet-printed micro-patterns and ensure smooth edges. This study provides insights into the formation of micro-patterns on low wettability surfaces.