Counteracting surface fogging to maintain surface transparency is important for a variety of applications including eyewear, windows and displays. Energy-neutral, passive approaches predominantly rely on engineering the surface wettability, but suffer from non-uniformity, contaminant deposition and lack of robustness, all of which substantially degrade durability and performance. Here, guided by nucleation thermodynamics, we design a transparent, sunlight-activated, photothermal coating to inhibit fogging. The metamaterial coating contains a nanoscopically thin percolating gold layer and is most absorptive in the near-infrared range, where half of the sunlight energy resides, thus maintaining visible transparency. The photoinduced heating effect enables sustained and superior fog prevention (4-fold improvement) and removal (3-fold improvement) compared with uncoated samples, and overall impressive performance, indoors and outdoors, even under cloudy conditions. The extreme thinness (~10 nm) of the coating—which can be produced by standard, readily scalable fabrication processes—enables integration beneath other coatings, rendering it durable even on highly compliant substrates.
Transparent sunlight-activated antifogging metamaterials
Company: ETH, Zürich, Switzerland
About the speaker:
Iwan Haechler is a PhD student in mechanical engineering at ETH Zurich. His research focuses on nanoengineering the interaction of light with matter, and how this can be beneficially employed for interfacial phase-change phenomena related to water. He holds a BSc and MSc in mechanical engineering from ETH Zurich and has gained research experience at the Lawrence Berkeley National Laboratory, Berkeley, USA. Moreover, he also served as an invited guest lecturer at the Smith School of Enterprise and Environment at the University of Oxford.