Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Using light to propel water : With new method, MIT engineers can control and separate fluids on a surface using only visible light

A new system developed by MIT engineers could make it possible to control the way water moves over a surface, using only light.

Image: Jose-Luis Olivares/MIT
A new system developed by MIT engineers could make it possible to control the way water moves over a surface, using only light. Image: Jose-Luis Olivares/MIT

Abstract:
A new system developed by engineers at MIT could make it possible to control the way water moves over a surface, using only light. This advance may open the door to technologies such as microfluidic diagnostic devices whose channels and valves could be reprogrammed on the fly, or field systems that could separate water from oil at a drilling rig, the researchers say.

Using light to propel water : With new method, MIT engineers can control and separate fluids on a surface using only visible light

Cambridge, MA | Posted on April 25th, 2017

The system, reported in the journal Nature Communications, was developed by MIT associate professor of mechanical engineering Kripa Varanasi, School of Engineering Professor of Teaching Innovation Gareth McKinley, former postdoc Gibum Kwon, graduate student Divya Panchanathan, former research scientist Seyed Mahmoudi, and Mohammed Gondal at the King Fahd University of Petroleum and Minerals in Saudi Arabia.

The initial goal of the project was to find ways of separating oil from water, for example, to treat the frothy mixture of briny water and crude oil produced from certain oil wells. The more thoroughly these mixtures are intermingled — the finer the droplets are — the harder they are to separate. Sometimes electrostatic methods are used, but these are energy-intensive and don’t work when the water is highly saline, as is often the case. Instead, the team explored the use of “photoresponsive” surfaces, whose responses to water can be altered by exposure to light.

By creating surfaces whose interactions with water — a property known as wettability — could be activated by light, the researchers found they could directly separate the oil from the water by causing individual droplets of water to coalesce and spread across the surface. The more the water droplets fuse together, the more they separate from the oil.

Photoresponsive materials have been widely studied and used; one example is the active ingredient in most sunscreens, titanium dioxide, also known as titania. But most of these materials, including titania, respond primarily to ultraviolet light and hardly at all to visible light. Yet only about 5 percent of sunlight is in the ultraviolet range. So the researchers figured out a way to treat the titania surface to make it responsive to visible light.

They did so by first using a layer-by-layer deposition technique to build up a film of polymer-bound titania particles on a layer of glass. Then they dip-coated the material with a simple organic dye. The resulting surface turned out to be highly responsive to visible light, producing a change in wettability when exposed to sunlight that is much greater than that of the titania itself. When activated by sunlight, the material proved very effective at “demulsifying” the oil-water mixture — getting the water and oil to separate from each other.

“We were inspired by the work in photovoltaics, where dye sensitization was used to improve the efficiency of absorption of solar radiation,” says Varansi. “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.”

“Saline water spreads out on our surface under illumination, but oil doesn’t,” says Kwon, who is now an assistant professor at the University of Kansas. “We found that virtually all the seawater will spread out on the surface and get separated from crude oil, under visible light.”

The same effect could also be used to drive droplets of water across a surface, as the team demonstrated in a series of experiments. By selectively changing the material’s wettability using a moving beam of light, a droplet can be directed toward the more wettable area, propelling it in any desired direction with great precision. Such systems could be designed to make microfluidic devices without built-in boundaries or structures. The movement of liquid — for example a blood sample in a diagnostic lab-on-a-chip — would be entirely controlled by the pattern of illumination being projected onto it.

“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,” Varanasi says. “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.”

The switchable wettability of these surfaces has another benefit: They can be largely self-cleaning. When the surface is switched from water-attracting (hydrophilic) to water-repelling (hydrophobic), any water on the surface gets driven off, carrying with it any contaminants that may have built up.

Since the photoresponsive effect is based on the dye coating, it can be highly tuned by selecting from among the thousands of available organic dyes. All of the materials involved in the process are widely available, inexpensive, commodity materials, the researchers say, and the processes for making them are commonplace.

The research was supported by the King Fahd University of Petroleum and Minerals, through the Center for Clean Water and Clean Energy at MIT and KFUPM.

###

Written by David L. Chandler, MIT News Office

####

For more information, please click here

Contacts:
Abby Abazorius
MIT News Office

617.253.2709

Copyright © Massachusetts Institute of Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

PAPER: Visible light guided manipulation of liquid wettability on photoresponsive surfaces

Related News Press

News and information

ICN2 researchers compute unprecedented values for spin lifetime anisotropy in graphene November 17th, 2017

Math gets real in strong, lightweight structures: Rice University researchers use 3-D printers to turn century-old theory into complex schwarzites November 16th, 2017

The stacked color sensor: True colors meet minimization November 16th, 2017

Nanometrics to Participate in the 6th Annual NYC Investor Summit 2017 November 16th, 2017

Mining/Extraction/Drilling

Promising sensors for submarines, mines and spacecraft: MSU scientists are developing nanostructured gas sensors that would work at room temperature November 10th, 2017

Microfluidics/Nanofluidics

Nano-SPEARs gently measure electrical signals in small animals: Rice University's tiny needles simplify data gathering to probe diseases, test drugs April 17th, 2017

Particle Works creates range of high performance quantum dots February 23rd, 2017

DNA 'barcoding' allows rapid testing of nanoparticles for therapeutic delivery February 7th, 2017

Zeroing in on the true nature of fluids within nanocapillaries: While exploring the behavior of fluids at the nanoscale, a group of researchers at the French National Center for Scientific Research discovered a peculiar state of fluid mixtures contained in microscopic channels January 11th, 2017

Discoveries

ICN2 researchers compute unprecedented values for spin lifetime anisotropy in graphene November 17th, 2017

Math gets real in strong, lightweight structures: Rice University researchers use 3-D printers to turn century-old theory into complex schwarzites November 16th, 2017

The stacked color sensor: True colors meet minimization November 16th, 2017

Counterfeits and product piracy can be prevented by security features, such as printed 3-D microstructures: Forgeries and product piracy are detrimental to society and industry -- 3-D microstructures can increase security -- KIT researchers develop innovative fluorescent 3-D stru November 15th, 2017

Announcements

ICN2 researchers compute unprecedented values for spin lifetime anisotropy in graphene November 17th, 2017

Math gets real in strong, lightweight structures: Rice University researchers use 3-D printers to turn century-old theory into complex schwarzites November 16th, 2017

The stacked color sensor: True colors meet minimization November 16th, 2017

Nanometrics to Participate in the 6th Annual NYC Investor Summit 2017 November 16th, 2017

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

ICN2 researchers compute unprecedented values for spin lifetime anisotropy in graphene November 17th, 2017

Math gets real in strong, lightweight structures: Rice University researchers use 3-D printers to turn century-old theory into complex schwarzites November 16th, 2017

The stacked color sensor: True colors meet minimization November 16th, 2017

Counterfeits and product piracy can be prevented by security features, such as printed 3-D microstructures: Forgeries and product piracy are detrimental to society and industry -- 3-D microstructures can increase security -- KIT researchers develop innovative fluorescent 3-D stru November 15th, 2017

Energy

Inorganic-organic halide perovskites for new photovoltaic technology November 6th, 2017

Dendritic fibrous nanosilica: all-in-one nanomaterial for energy, environment and health November 4th, 2017

New nanomaterial can extract hydrogen fuel from seawater: Hybrid material converts more sunlight and can weather seawater's harsh conditions October 4th, 2017

Researchers set time limit for ultrafast perovskite solar cells September 22nd, 2017

Water

A new way to mix oil and water: Condensation-based method developed at MIT could create stable nanoscale emulsions November 8th, 2017

Magnetized viruses attack harmful bacteria: Rice, China team uses phage-enhanced nanoparticles to kill bacteria that foul water treatment systems August 2nd, 2017

Bacteria-coated nanofiber electrodes clean pollutants in wastewater July 1st, 2017

Smart materials used in ultrasound behave similar to water, Penn chemists report June 16th, 2017

Photonics/Optics/Lasers

Math gets real in strong, lightweight structures: Rice University researchers use 3-D printers to turn century-old theory into complex schwarzites November 16th, 2017

Practical superconducting nanowire single photon detector with record detection efficiency over 90 percent November 9th, 2017

Metal-silicone microstructures could enable new flexible optical and electrical devices: Laser-based method creates force-sensitive, flexible microstructures that conduct electricity November 1st, 2017

Nanoparticles with pulse laser controlled antibacterial properties October 26th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project