Oil and water don’t mix, but they can make a messy froth that makes it difficult to separate the two. In an effort to keep the two separated, engineers at MIT are literally shining a light on the problem. Using special organic dyes, the researchers have come up with a system that controls how water moves on a surface, which may one day help clean up oil drilling and also holds the promise of creating microfluidic diagnostic devices that can be redesigned at the push of a button.
Drilling for oil is a dirty business. One particularly unpleasant problem is when oil and water try to mix. Some types of drilling use an injection of brine into the well and what comes up is often briny water mixed with oil droplets in a fine, frothy suspension. According to MIT, there are ways of separating this brown-black foam, including the use of electrostatic devices, but they tend to be energy hogs and aren’t effective if the water is too saline.
The MIT team’s approach involved looking at a different type of oil – suntan oil. Most sunscreens use titanium dioxide as their active ingredient to protect against the sun, and it has a bit of a Jekyll and Hyde nature. When in the dark or exposed to visible light, titanium oxide repels water, but when it’s exposed to ultraviolet light, it attracts water and becomes wettable.
“By systematically studying the relationship between the energy levels of the dye and the wettability of the contacting liquid, we have come up with a framework for the design of these light-guided liquid manipulation systems,” says Varanasi. “By choosing the right kind of dye, we can create a significant change in droplet dynamics. It’s light-induced motion – a touchless motion of droplets.”
Source/More: MIT News