Sol-gel inks for direct-write assembly of functional oxides

A study was conducted to develop a range of sol-gel inks that enable the direct ink writing (DIW) of functional oxides at the microscale level. The ink viscosity for DIW was developed through micro-sized nozzles, by regulating the solids content. An approximation of the Hagen-Poiseuille model was used to estimate the range of ink viscosity. The ink filaments were calcined at high temperature conditions, to produce the desired functional oxide phases. 3D micro-periodic structures composed of parallel arrays of orthogonally stacked rods were also produced, to demonstrate that DIW assembly of sol-gel inks creates a new potential for functional devices. It was observed that the sacrificial layer melted, allowing the patterned 3D structure to first release from the underlying surface, before shrinking isotropically during calcination.