A team of engineers at MIT recently came up with a new system that allows the users to control water movement on the surface with the help of light. This new development may open up scope for several new developing technologies like microfluidic diagnostic devices whose valves and channels can easily be reorganized on field or fly systems that would separate oil from water at drilling rigs. The team working on this project had Kripa Varanasi as the head who is also an associate professor of mechanical engineering at MIT. the rest of the team had members from King Fahd University of Petroleum and Minerals from Saudi Arabia and MIT.
The primary goal of this project was to discover ways for separating water from oil. The more thoroughly such mixtures are intermingled the smaller and finer the droplets are and harder it becomes to separate the two. As the water is saline, you can’t even think of using electrostatic procedures. Therefore, the team explored new ways like use of “photoresponsive” surfaces, responses of these can always be altered with slight exposure to light. They achieved the target by formulating surfaces whose interactions with water can easily be activated with light. The property is known as wettability and it helped the research team in direct separation of oil from water by coalescing of individual water droplets and by spreading these over the surface. The higher the number of water droplets fusing into each other, the better it is to separate these from oil.
Varanasi adds, “We were inspired by the work in photovoltaics, where dye sensitization was used to improve the efficiency of absorption of solar radiation. The coupling of the dye to titania particles allows for the generation of charge carriers upon light illumination. This creates an electric potential difference to be established between the surface and the liquid upon illumination, and leads to a change in the wetting properties.”
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