Process mechanism for vacuum-assisted microfluidic lithography with ceramic colloidal suspensions

The infiltration kinetics and the drying mechanism of suspensions involved in vacuum-assisted microfluidic lithography (μFL) have been investigated for the fabrication of complex micropatterned ceramic structures. Infiltration lengths of alumina suspensions with various solid loadings into microchannels were analyzed as a function of channel widths ranging from 10 to 100 lm. The use of well-dispersed ethanol-based suspensions with lower viscosities and wider channels allowed for easier and longer infiltration due to lower fluidic resistance in the channels. In contrast to the micromolding in capillaries (MIMIC) method, vacuum-assisted μFL has a distinct drying mechanism in which there is a critical level of solid loading of the suspension with respect to the volume of the microchannel for the fabrication of a defect-free pattern structure.