Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > “Active” surfaces control what’s on them: Researchers develop treated surfaces that can actively control how fluids or particles move

Diagram shows the droplet on the ferrofluid impregnated surface. The oil-based solution keeps the droplet from being pinned to the surface and allows it to move freely.

Image courtesy of the researchers
Diagram shows the droplet on the ferrofluid impregnated surface. The oil-based solution keeps the droplet from being pinned to the surface and allows it to move freely.

Image courtesy of the researchers

Abstract:
Researchers at MIT and in Saudi Arabia have developed a new way of making surfaces that can actively control how fluids or particles move across them. The work might enable new kinds of biomedical or microfluidic devices, or solar panels that could automatically clean themselves of dust and grit.



Watch a water droplet get pulled across an "active" surface designed by MIT researchers.

Video: Melanie Gonick/MIT

“Active” surfaces control what’s on them: Researchers develop treated surfaces that can actively control how fluids or particles move

Cambridge, MA | Posted on August 6th, 2014

"Most surfaces are passive," says Kripa Varanasi, an associate professor of mechanical engineering at MIT, and senior author of a paper describing the new system in the journal Applied Physics Letters. "They rely on gravity, or other forces, to move fluids or particles."

Varanasi's team decided to use external fields, such as magnetic fields, to make surfaces active, exerting precise control over the behavior of particles or droplets moving over them.

The system makes use of a microtextured surface, with bumps or ridges just a few micrometers across, that is then impregnated with a fluid that can be manipulated — for example, an oil infused with tiny magnetic particles, or ferrofluid, which can be pushed and pulled by applying a magnetic field to the surface. When droplets of water or tiny particles are placed on the surface, a thin coating of the fluid covers them, forming a magnetic cloak.

The thin magnetized cloak can then actually pull the droplet or particle along as the layer itself is drawn magnetically across the surface. Tiny ferromagnetic particles, approximately 10 nanometers in diameter, in the ferrofluid could allow precision control when it's needed — such as in a microfluidic device used to test biological or chemical samples by mixing them with a variety of reagents. Unlike the fixed channels of conventional microfluidics, such surfaces could have "virtual" channels that could be reconfigured at will.

While other researchers have developed systems that use magnetism to move particles or fluids, these require the material being moved to be magnetic, and very strong magnetic fields to move them around. The new system, which produces a superslippery surface that lets fluids and particles slide around with virtually no friction, needs much less force to move these materials. "This allows us to attain high velocities with small applied forces," says MIT graduate student Karim Khalil, the paper's lead author.

The new approach, he says, could be useful for a range of applications: For example, solar panels and the mirrors used in solar-concentrating systems can quickly lose a significant percentage of their efficiency when dust, moisture, or other materials accumulate on their surfaces. But if coated with such an active surface material, a brief magnetic pulse could be used to sweep the material away.

"Fouling is a big problem on such mirrors," Varanasi says. "The data shows a loss of almost 1 percent of efficiency per week."

But at present, even in desert locations, the only way to counter this fouling is to hose the arrays down, a labor- and water-intensive method. The new approach, the researchers say, could lead to systems that make the cleaning process automatic and water-free.

"In the desert environment, dust is present on a daily basis," says co-author Numan Abu-Dheir of the King Fahd University of Petroleum and Minerals (KFUPM) in Saudi Arabia. "The issue of dust basically makes the use of solar panels to be less efficient than in North America or Europe. We need a way to reduce the dust accumulation."

One advantage of the new active-surface system is its effectiveness on a wide range of surface contaminants: "You want to be able to propel dust or liquid, many materials on surfaces, whatever their properties," Varanasi says.

MIT postdoc Seyed Mahmoudi, a co-author of the paper, notes that electric fields cannot penetrate into conductive fluids, such as biological fluids, so conventional systems wouldn't be able to manipulate them. But with this system, he says, "electrical conductivity is not important."

In addition, this approach gives a great deal of control over how material moves. "Active fields — such as electric, magnetic, and acoustic fields — have been used to manipulate materials," Khalil says. "But rarely have you seen the surface itself interact actively with the material on it," he says, which allows much greater precision.

While this initial demonstration used a magnetic fluid, the team says the same principle could be applied using other forces to manipulate the material, such as electric fields or differences in temperature.

Neelesh Patankar, a professor of mechanical engineering at Northwestern University who was not involved in this work, says this research "introduces a new class of approach for droplet-based microfluidic platforms, which have numerous applications in a variety of fields, including biotechnology." He adds, "This work cleverly combines low-hysteresis droplet movement with low-magnetic-field-driven droplet propulsion to achieve impressive capabilities."

The work was supported by the MIT-KFUPM Center for Clean Water and Clean Energy.

####

For more information, please click here

Contacts:
Andrew Carleen

Phone: 617-253-1682
MIT News Office

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 News Press

News and information

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Deep Space Industries and SFL selected to provide satellites for HawkEye 360’s Pathfinder mission: The privately-funded space-based global wireless signal monitoring system will be developed by Deep Space Industries and UTIAS Space Flight Laboratory May 26th, 2016

Videos/Movies

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Programmable materials find strength in molecular repetition May 23rd, 2016

Graphene makes rubber more rubbery May 23rd, 2016

ORNL demonstrates large-scale technique to produce quantum dots May 21st, 2016

Microfluidics/Nanofluidics

Little ANTs: Researchers build the world's tiniest engine May 3rd, 2016

POSTECH researchers develop a control algorithm for more accurate lab-on-a-chip devices April 6th, 2016

Microfluidic devices gently rotate small organisms and cells March 24th, 2016

New microwave imaging approach opens a nanoscale view on processes in liquids: Technique can explore technologically and medically important processes that occur at boundaries between liquids and solids, such as in batteries or along cell membranes March 16th, 2016

Discoveries

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Finding a new formula for concrete: Researchers look to bones and shells as blueprints for stronger, more durable concrete May 26th, 2016

Announcements

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Deep Space Industries and SFL selected to provide satellites for HawkEye 360’s Pathfinder mission: The privately-funded space-based global wireless signal monitoring system will be developed by Deep Space Industries and UTIAS Space Flight Laboratory May 26th, 2016

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

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Finding a new formula for concrete: Researchers look to bones and shells as blueprints for stronger, more durable concrete May 26th, 2016

Energy

Harnessing solar and wind energy in one device could power the 'Internet of Things' May 26th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Light can 'heal' defects in new solar cell materials: Defects in some new electronic materials can be removed by making ions move under illumination May 24th, 2016

Technique improves the efficacy of fuel cells: Research demonstrates a new phase transition from metal to ionic conductor May 18th, 2016

Research partnerships

Finding a new formula for concrete: Researchers look to bones and shells as blueprints for stronger, more durable concrete May 26th, 2016

The next generation of carbon monoxide nanosensors May 26th, 2016

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Light can 'heal' defects in new solar cell materials: Defects in some new electronic materials can be removed by making ions move under illumination May 24th, 2016

Solar/Photovoltaic

Harnessing solar and wind energy in one device could power the 'Internet of Things' May 26th, 2016

Light can 'heal' defects in new solar cell materials: Defects in some new electronic materials can be removed by making ions move under illumination May 24th, 2016

This 'nanocavity' may improve ultrathin solar panels, video cameras and more May 16th, 2016

New research shows how silver could be the key to gold-standard flexible gadgets: Silver nanowires are an ideal material for current and future flexible touch-screen technologies May 13th, 2016

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







Car Brands
Buy website traffic