The additive manufacturing of electro-ceramics is a major technological challenge with many possible applications. The technology can prototype and produce in small volume production, custom dielectric, piezoelectric and solid state ionic devices. Sandia National Laboratories was the birthplace of modern, 3-D ceramic additive manufacturing. The newly developed manufacturing methods are considered to be the foundation of 3-D printing via particulate slurries and our spin off company Robocasting Enterprises, is commercially producing dense ceramic and composite parts. These parts are used in various applications including complex geometry catalyst supports and casting filters. This technique is based on the layer-by-layer deposition of highly loaded colloidal slurries that are extruded through a small nozzle. The rheology of the slurry is crucial in order to maintain the structural integrity of the part being built, as Robocasting does not rely on polymerization reactions or solidification to retain shape after extrusion. Since this process is essentially binderless, a dense ceramic part can typically be freeformed, dried, and sintered in less than 24 hours.

Although Robocasting is a highly useful technique, it has been optimized for ceramic and composite materials. More recently there has been some work on expanding this technology for use in printing electrode materials. Printing conductors and other structures for electrochemical and electronics using direct write technology gives the potential to reduce production time and reduce waste of expensive material. We have demonstrated that this direct write manufacturing technique can produce Multi-Chip Modules (MCM) by depositing silver and gold on Low Temperature Co-fired Ceramics (LTCC). We have also applied this additive manufacturing technique to our unique design of electrochemical gas sensors. These multi-component mixed potential sensors consist of solid electrodes and a porous electrolyte. In order to expand the versatility of this manufacturing method to be used in solid state ionic devices, slurries of solid electrolytes and electrode materials with specific rheological properties were developed. Another challenge was controlling the residual stress and shrinkage through the material properties of various components. These devices are capable of detecting NO_x, hydrocarbons, and NH₃ at concentrations on the order of parts per million. The additive manufacturing technique allows for the rapid prototyping of these devices and low volume production of custom devices optimized for specific applications.