Investigating the contributions of electrostatic and capillary effects in anti-dust nanostructures.

Dust contamination is a key challenge for deployment of optics in harsh environments, maintenance of photovoltaics, and the pursuit of sustainable interplanetary exploration. In this work, the dust mitigation properties of nanostructured substrates with thin insulating and conductive coatings are investigated. To examine the contribution of capillary, electrostatic, and van der Waals forces to the surface's overall dust adhesion, the relative humidity is varied to control their relative contributions. Experiments show that samples with conductive coatings can have up to 91.0% less coverage than insulating sample under low humidity. The results indicate that the electrical properties of surface coatings play a significant role in mitigating dust adhesion forces at low humidities, where electrostatic forces dominate. In addition, reduced surface energy and nanostructured features are key for an improved anti-dust performance at all humidities. The results demonstrate that the nanostructure with conductive coatings is highly anti-dust and has less than 2.5% percentage area coverage throughout the humidity range. This research improves understanding of the interparticle forces between substrate and particulate and explores viable alterations of surface geometry and chemistry for passive dust mitigation that are applicable across a broad humidity range.