07 July 2014 Giant leap for omniphobic and transparent surfaces

Superomniphobic and transparent nano-structured surface

ICFO & Corning report on Super-omniphobic, transparent and anti-reflection surfaces based on hierarchical nano-structures. In a recent study published in Nano Letters, the Optoelectronics research group led by ICREA Professor at ICFO Valerio Pruneri, in collaboration with Corning Incorporated and nGimat, both companies from the USA, was able to achieve static contact angles of more than 170º and 160º for water and oil by exploiting a hierarchical geometry made of two-tier nano-structures achieving the highest optical performances in conjunction with super-omniphobicity reported to date.

Optical surfaces that can repel both water and oil have much potential for applications in a diverse array of technologies including self-cleaning solar panels, anti-icing windows, windshields for automobiles and aircrafts, low-drag surfaces and anti-smudge touch screens.

So far previous studies were able to achieve omniphobicity at the expense of light transparency and through visibility, which are essential for many applications. Researchers at ICFO went a step further superposing a first layer of nano-pillars of length scale ~100-200nm, monolithically integrated in the glass surface using lithography-free metal dewetting followed by reactive ion etching, with a secondary branching nanostructures made of nano-particles of length scale ~10-30nm,deposited via a NanoSpraySM combustion chemical vapor deposition. By doing this, they created a surface that presented not only a significantly reduced reflection (<0.5%) but also an increased transmission (93.8% average over the 400 to 700 nm wavelength range) and very low scattering values (about 1% haze).

This work has been able to show and confirm that all these techniques are industrially scalable, thus ensuring future mass-production of large transparent super-omniphobic surfaces.