Researchers from Aalto University have created unique surfaces that cause oil to transport itself to specified locations, directions which have been pre-selected. The oleophobic surfaces created by researchers are microtextures with radial arrays of undercut stripes.

When oil drops find their way onto these surfaces, drops are forces to move away from the place they have landed to a direction set by asymmetric geometrical patterning of the surface. These surfaces open up completely new avenues that do not require power in order to transport liquid as well as oil contamination self-removal applications in analytical and fluidic devices.

Postdoctoral Researcher Ville Jokinen says the team has developed surfaces that hold the ability to move liquid oil droplets by surface tension forces. Droplets from anywhere inside the pattern will find their way to the center of the pattern. Xuelin Tian, another postdoctoral researcher involved in the team says that although surface engineering facilitates effective liquid manipulation and allows water droplets to transport on their own with the help of synthetic surfaces, self-transportation of oil droplets posed the team with a major challenge due to their low surface tension.

There are new surfaces in the works that are also able to move low surface tension liquids other than oil. They can currently work with water, wine and even pure forms of ethanol. Directional liquid transportation of water is something that naturally occurs in nature. A great example of this is in cactus needles and the shells of desert beetles. Researchers see a range of industrial applications which they would like to continue to explore and expand in the near future.

Professor Robin Ras explains that droplets position themselves very accurately within the center of the pattern. This could be used to deposit arrays of functional materials. The team envisions the patterns holding the ability to be used the other way around as well. For example, in the transportation of unwanted stray droplets away from critical areas of devices, such as to prevent nozzle clogging in inkjet printing.

Of course, this is just the beginning of the research. The team says they still have a way to go but they are planning big things and are excited to see what they uncover next. In this type of research, you never know what you may find and each new discovery holds the capability of venturing out even further into applications no one may have envisioned at the start.

The full study was published in the Science Advances journal.