Integration of Great Water Repellence and Imaging Performance on a Superhydrophobic PDMS Microlens Array by Femtosecond Laser Microfabrication

Microlens arrays (MLAs), as the important optical devices, are easily polluted by the water droplets or power-like-contaminates in the air. Endowing the artificial MLAs with anti-water and self-cleaning abilities remains great challenge. In this paper, the authors report a novel method for fabricating superhydrophobic polydimethylsiloxane (PDMS) MLAs by the combination of femtosecond laser wet etching and femtosecond laser direct writing methods. The resultant surface is composed of a convex MLA and the surrounding rough micro/nanoscale hierarchical structures. Water droplet on the surface of the as-prepared MLA shows a contact angle of 162° and can easily roll away when the substrate is slightly tilted 0.5°. In addition to their excellent imaging performance, such ultralow adhesive and ultrahigh superhydrophobicity also endows the as-prepared MLA with excellent anti-water ability as well as the self-cleaning function relative to the normal MLA. The authors believe that the anti-water and self-cleaning MLAs will potentially have many important applications in solar cells, medical endoscopes, and other optical systems that are often used in the humid environment or outdoors.