  The controlled handling of liquids and colloidal suspensions as they interact
with surfaces, targeting a broad palette of related functionalities, is of
great importance in science, technology, and nature. When small liquid volumes
need to be processed in microfluidic devices, contamination on the solid-liquid
interface and loss of liquid due to adhesion on the transport channels are two
very common problems that can significantly alter the process outcome, e.g. the
chemical reaction efficiency, or the purity and the final concentrations of a
suspension. It is therefore no surprise that both levitation and minimal
contact transport methods including non wetting surfaces have been developed to
minimize the interactions between liquids and surfaces. Here we demonstrate
contactless surface levitation and transport of liquid drops, realized by
harnessing and sustaining the natural sublimation of a solid carbon
dioxide-coated substrate to generate a continuous supporting vapor layer. The
capability and limitations of this technique in handling liquids of extreme
surface tension and kinematic viscosity values are investigated both
experimentally and theoretically. The sublimating coating is capable of
repelling many viscous and low surface tension liquids, colloidal suspensions,
and non-Newtonian fluids as well, displaying outstanding omniphobic properties.
Finally, we demonstrate how sublimation can be used for liquid transport,
mixing and drop coalescence, with a sublimating layer coated on an underlying
substrate with prefabricated channels, conferring omniphobicity with a simple
physical approach, rather than a chemical one.
