Spatial control of condensation and desublimation using ice nucleating proteins

On a subfreezing surface, nucleating embryos usually form as supercooled condensate that later freezes into ice, as opposed to desublimation. Ice nucleating proteins (INPs) have been widely used to quickly freeze existing supercooled water; however, nobody has studied how they might affect the initial mode of embryo formation. We show that INPs deposited on a substrate can switch the mode of embryo nucleation to desublimation, rather than supercooled condensation, beneath a critical temperature. By patterning a hydrophobic surface with an array of hydrophilic stripes, the INPs can be selectively deposited by evaporating water that exclusively spreads along the hydrophilic regions. The resulting array of desublimating ice stripes created dry zones free of condensation or frost in the intermediate areas, as the hygroscopic ice stripes served as overlapping humidity sinks.