Directional anchoring patterned liquid-infused superamphiphobic surfaces for high-throughput droplet manipulation

Abstract

High-throughput experiments involving isolated droplets based on patterned superwettable surfaces are important for various applications related to biology, chemistry, and medicine, and they have attracted a large amount of interest. This paper provides a directional anchoring liquid-infused superamphiphobic surface (DAS), via combining concepts based on the droplet-anchoring behavior of beetle backs with patterned wettability, the directional adhesion of butterfly wings, and the slippery liquid-infused surfaces (SLISs) of pitcher plants. Regularly arranged “>”-shaped SLIS patterns were created on a superamphiphobic (SAM) background through ultrafast-laser-based technology. Improved directional anchoring abilities with a sliding angle difference of 77° were achieved; this is the largest sliding angle difference in a one-dimensional direction achieved using an artificial surface, to the best of the authors' knowledge. Thanks to the directional anchoring abilities, the DAS coupled droplet ‘anchoring’ and ‘releasing’ abilities. Furthermore, a high-throughput droplet manipulation device was designed, on which a micro-droplet array with a large number of droplets can be ‘captured’, ‘transferred’, or ‘released’ in a single step. With the addition of lubricant, the DAS can work continuously for even more than 30 cycles without cross-contamination between different droplets. The DAS also shows good stability under an ambient atmosphere and can maintain its functionality when manipulating corrosive droplets. The DAS and corresponding high-throughput droplet manipulation method are excellent candidates for practical applications.