Passive Antifrosting Surfaces Using Microscopic Ice Patterns
mediaposted on 13.09.2018, 19:50 by S. Farzad Ahmadi, Saurabh Nath, Grady J. Iliff, Bernadeta R. Srijanto, C. Patrick Collier, Pengtao Yue, Jonathan B. Boreyko
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Despite exceptional recent advances in tailoring the wettability of surfaces, to date, no engineered surface can passively suppress the in-plane growth of frost that invariably occurs in humid, subfreezing environments. Here, we show that up to 90% of a surface can exhibit passive antifrosting by using chemical or physical wettability patterns to template “ice stripes” across the surface. As ice exhibits a depressed vapor pressure relative to liquid water, these sacrificial ice stripes siphon the supersaturated water vapor to keep the intermediate surface areas dry from dew and frost. Further, we show that when these sacrificial ice stripes are elevated atop microfins, they diffusively coarsen in a suspended state above the surface. The suspended state of the coarsening ice results in a diffusive growth rate an order of magnitude slower than frost coarsening directly on a solid substrate and should also minimize its adhesive strength to the surface.