One-step fabricated wettable gradient surface for controlled directional underwater oil-droplet transport

Abstract

A wettable gradient surface for underwater oil is fabricated by a one-step anodic oxidation method on a graphite plate and self-propulsion of an underwater oil droplet is achieved on it. Moreover, the transport distance could be further controlled and predicted via the initial position of the droplet and/or tilted angle of the graphite plate. Such surfaces with a continuous wettable gradient for underwater oil may be used for the construction of new smart devices.