Pillars or Pancakes? Self-cleaning surfaces without coating

Naureen Akhtar, Peter J. Thomas, Benny Svardal, Stian Almenningen, Edwin de Jong, Stian Magnussen, Patrick Onck, Martin Anders Fernø, Bodil Holst

OnderzoeksoutputAcademicpeer review

10 Citaten (Scopus)
523 Downloads (Pure)


Surfaces that stay clean when immersed in water are important for an enormous range of applications from ships and buildings to marine, medical and other equipment. Up till now the main strategy for designing self-cleaning surfaces has been to combine hydrophilic/hydrophobic coatings with high aspect ratio structuring (typically micron scale pillars) to trap a (semi-)static water/air layer for drag and adhesion reduction. However, such coating and structuring can distort optical properties; get damaged in harsh environments; and contamination, i.e. particles, oil droplets and biofouling, can get trapped and aggregate in the structure. Here we present a radically different strategy for self-cleaning surface design: We show that a surface can be made self-cleaning by structuring with a pattern of very low aspect ratio pillars (“pancakes”). Now the water is not trapped. It can flow freely around the “pancakes” thus creating a dynamic water layer. We have applied the new pancake design to sapphire windows and made the first surfaces that are self-cleaning through structuring alone without the application of any coating. An offshore installation has now been running continuously with structured windows for more than one year. The previous uptime for unstructured windows was 7 days.
Originele taal-2English
Pagina's (van-tot)7509-7514
Aantal pagina's6
TijdschriftNano Letters
Nummer van het tijdschrift12
Vroegere onlinedatum26-okt-2018
StatusPublished - dec-2018

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