Controlling Inkjet Fluid Kinematics to Achieve SOFC Cathode Micropatterns

Drop-on-demand inkjet printing - a mask-less, fine write, and high throughput technique - is attractive for fabricating miniature ceramic devices. In this study, high quality, fine-featured solid oxide fuel cell (SOFC) cathode micropatterns were demonstrated using inkjet printing. The influence of the droplet kinematic properties on final drop deposition was studied by adjusting ink temperature and droplet velocity to obtain a wide range of Weber and Z values, i.e. 0 < Weber < 57 and 0 < Z < 24. Terpineol-based inks were evaluated, with or without dispersant (polymeric ethyl cellulose) and/or active cathode material (La 0.6 Sr 0.4 Fe 0 . 8 Co 0.2 O 3 ). The balance of inertia to the surface energy of the jetted droplet was found to play a prominent role in the stability of droplets. The Weber number was found to be the good predictor for stable jetting. At Weber > 35 printing defects from splashes and satellites were present. At Weber < 35 the droplets coalesced into uniform, round circles without splashes or satellite defects. Defect-free printing was essential toward achieving uniform micropatterens such as micro dot arrays or micro lines which are on the scale of 100 microns or less.