Understanding Key Factors during Dod Inkjet Printing Towards Precise Fabrication of Micro Energy Systems

Abstract

There is an ever-increasing need for micro energy systems that can power miniature, unmanned, or remotely-located devices. Drop-on-Demand (DOD) inkjet fabrication is uniquely positioned for this demand due to its low-cost processing with microscale resolution, high throughput, reproducibility, and ease in shape design. This study seeks to capitalize on the advantages of DOD inkjet printing for application to manufacturing micro energy conversion/storage systems, by defining the fundamental jet kinematics and key factors underpinning the inkjet printing process.The ink used in this study was a dilute colloidal ink suspension composed of a common solid oxide fuel cell (SOFC) cathode material [La0.6Sr0.4Fe0.8Co0.2O3 (LSFC)] and organic solvent α-terpineol. The results were evaluated systematically in terms os final deposition quality, resolution, and microstructure. Favorable fluid kinematics were identified that attained uniform, well-shaped, circular 0-D dots about 0.1 µm thick and 60 µm in diameter. To increases the microfeature thickness and x/y plane dimensions , multiple and/or sequential ink passes were employed. For printing 1-D lines, the spacing between droplets was imperative to fabricating quality micro features. Using appropriate conditions, 1-D lines with x/y dimensions < 100 µm and controllable z axis dimensions at 0.1 µm per printing pass with dense, open or networked microstructures were demonstrated. 2-D planes at the dimensions as small as 100 µm by 100 µm were also achieved with smooth surface and continuous intra-planar ceramic coverage. In the course of post-processing the inkjetted cathodes, it was observed that the submicron cathode films printed at optimal conditions, after being sintered at controlled conditions, were uniform, smooth and free of cracks or delamination.This research demonstrated through fundamental understanding and control of the inkjet fabrication process, cathode features can be printed with controlled dimension and quality towards producing a functioning micro SOFC operable at low temperatures. The knowledge gained from this research will be appliable to other micro energy conversion and storage systems.