Tunable Multimodal Drop Bouncing Dynamics and Anti-Icing Performance of a Magnetically Responsive Hair Array

Abstract

Anti-icing materials that can efficiently limit ice formation have a strong potential to replace existing anti-icing techniques, such as Joule heating, chemical release, or mechanical removal, which are usually inefficient, expensive, and environmentally harmful. In this study, an anti-icing material based on a magnetically responsive hierarchical hair array that can actively modulate drop bouncing dynamics is presented. The magnetically responsive hair array exhibits an immediate and reversible structural bending motion in response to an external magnetic field. The array also exhibits superhydrophobicity, regardless of its tilt angle, due to the tapered geometry of the hairs and the multiscale surface roughness of the array. Due to its dynamic structure and water-repellent characteristics, the array can induce distinct multiple modes of drop bouncing behavior by adjusting its structural bending state in a reversible fashion. Three different types of bouncing behavior, namely, quasi-pancake bouncing, directional bouncing, and macrotexture-induced droplet fragmentation, can be obtained with the vertical, tilted, and fully bent hair arrays, respectively. We demonstrate that the dynamically controllable drop bouncing behavior of the magnetically responsive hierarchical array enables the efficient and robust prevention of ice formation and accumulation.

Magneto‐Responsive Shutter for On‐Demand Droplet Manipulation

“…MRSS with various structured topographies including conical array, microcilia array, [ 1 , 2 , 7 , 23 , 24 ] micropillars, [ 25 , 26 , 27 , 28 , 29 , 30 , 31 ] and microplates have been designed for dynamical droplet manipulation under magnetic actuation. [ 6 , 21 , 32 , 33 ] For example, magneto‐responsive conical array was employed for static fog collection under windless regions.…”

“…[ 1 ] Magneto‐responsive arrays of microcilia and micropillars can realize switchable wettability, [ 2 , 20 , 23 ] reversible adhesion, [ 31 ] directional droplet transportation, [ 7 , 22 , 26 , 34 , 35 ] and droplet bouncing. [ 24 ] MRSS with magneto‐responsive Janus microplates enabled reversible switch between superhydrophobic and hydrophilic states, [ 21 ] and achieved 3D droplet transport. [ 6 ] In the above MRSS, their surface microstructures undergo large bending under an oblique magnetic field, resulting in formation of switchable microstructured surfaces with anisotropic wettability for dynamic droplet manipulation.…”

Superhydrophobic materials used for anti-icing Theory, application, and development

“…The use of micro-patterned nanowire arrays facilitates the spontaneous outward movement of droplets for rapid droplet removal ( Wen et al., 2017 ). In addition, Lee et al. (2018a) proposed an SH material based on the magnetic response type layered hair array, which was capable of adjusting the bending state of the hair array structure through the external magnetic field to induce various droplet bouncing behaviors in different modes, which was able to effectively remove water droplets on the surface and effectively prevent surface icing behavior ( Lee et al., 2018a ).…”

Smart Bionic Surfaces with Switchable Wettability and Applications

“…Magnetic field-driven reversible wettability can dynamically control surface features by embedding magnetic particles or magnetic fluids [79,80] . The magnetic-induced mechanism is mainly attributed to the changes in surface microstructures [81][82][83][84][85][86] . Combining spray coating with magnetic-field-directed selfassembly, Yang et al fabricated a magnetic-responsive Fig.…”