Dynamic Defrosting on Nanostructured Superhydrophobic Surfaces

Abstract

Water suspended on chilled superhydrophobic surfaces exhibits delayed freezing; however, the interdrop growth of frost through subcooled condensate forming on the surface seems unavoidable in humid environments. It is therefore of great practical importance to determine whether facile defrosting is possible on superhydrophobic surfaces. Here, we report that nanostructured superhydrophobic surfaces promote the growth of frost in a suspended Cassie state, enabling its dynamic removal upon partial melting at low tilt angles (<15°). The dynamic removal of the melting frost occurred in two stages: spontaneous dewetting followed by gravitational mobilization. This dynamic defrosting phenomenon is driven by the low contact angle hysteresis of the defrosted meltwater relative to frost on microstructured superhydrophobic surfaces, which forms in the impaled Wenzel state. Dynamic defrosting on nanostructured superhydrophobic surfaces minimizes the time, heat, and gravitational energy required to remove frost from the surface, and is of interest for a variety of systems in cold and humid environments.

Air-stable droplet interface bilayers on oil-infused surfaces

“…The silicon nanopillars were fabricated using a lithography-free technique adapted from a previous report (66). First, 100 nm of silicon dioxide (SiO 2 ) was thermally grown onto a 〈100〉 Si substrate and 5 nm of platinum was then deposited onto the SiO 2 using an electron beam evaporator.…”

Simple Approach to Superhydrophobic Nanostructured Al for Practical Antifrosting Application Based on Enhanced Self-propelled Jumping Droplets

“…Once the condensate droplets freeze to form a frost layer, impinging water droplets like rain drops freeze immediately when they touch it, and this process may exacerbate icing problems. In addition, removing these frost layer is costly and requires much energy 6 .…”

Length Scale Selects Directionality of Droplets on Vibrating Pillar Ratchet

“…The resulting dewet Pt layer then served as a mask during anisotropic reactive ion etching (RIE) of the SiO 2 and Si. [27][28][29][30] The RIE was carried out in an Oxford PlasmaLab system (Oxford Instruments, UK) using glancingangle RIE with the wafer sitting on an aluminum holder bent to an angle of 70° relative to the surface of a silicon carrier wafer. A perfl uorinated oil (Fomblin 25/5) was placed between the wafer and the aluminum holder to ensure even heat transfer during etching.…”

“…The ideas of designing and using asymmetric micro-or nanostructures are often mimics of biological objects, such as the hierarchical method based on metal dewetting. [27][28][29][30] Microscale diameter pillars were fabricated using common photolithography masking techniques. The fabrication method, shown schematically in Figure 1 , resulted in arrays tilted nominally 30° off normal.…”