Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers develop optical displays from water and air

14.06.2012
For many years, scientists have been pursuing ways to mimic the perplexing capability of the lotus leaf to repel water. Lotus leaves hate water so much that droplets effortlessly roll off the surface, keeping it clean from dirt.
Now an international team of researchers led by Aalto University have come up with an entirely new concept of writing and displaying information on surfaces using simply water. They exploit the unique way a trapped layer of air behaves on a lotus-inspired dual-structured water-repelling surface immersed under water.

To achieve the extreme water-repellency of the lotus leaf, a surface needs to be superhydrophobic: it must have microscopic surface structures that prevent water from wetting the surface completely, leaving a thin layer of air between water and the surface. When such a surface is immersed in water, a trapped air layer covers the entire surface.

The researchers lead by Dr. Robin Ras at Aalto University in Finland, University of Cambridge and Nokia Research Center Cambridge fabricated a surface with structures in two size scales: microposts that have a size of ten micrometers and tiny nanofilaments that are grown on the posts. On such a two-level surface the air layer can exist in two different shapes (wetting states) that correspond to the two size scales. The researchers found that one can easily switch between the two states locally using a nozzle to create over- or underpressure in the water, in order to change the air layer to either state.

“The minimal energy needed to switch between the states means the system is bistable, which is the essential property of memory devices, for example”, Academy Research Fellow Dr. Robin Ras points out. However, there is a feature that makes it all the more interesting: there is a striking optical contrast between the states due to a change in the roughness of the water-air interface. “Combined with the optical effect, the surface is also a bistable reflective display.”

The switching only involves a change in the shape of the air layer − nothing happens to the solid surface itself. This is demonstrated by writing shapes on the surface underwater (making use of the contrast between the states) and taking the sample out of water: the surface emerges completely dry, and no traces of the writing remain.

The method for manipulating the air layer with the nozzle was developed by Tuukka Verho, graduate student in Aalto University. He was able to show that the reversible switching can be done with precision in a pixel-by-pixel fashion.

“This result represents the first step in making non-wettable surfaces a platform for storing or even processing information”, says Academy professor Olli Ikkala. Until now, lotus-inspired surfaces have been mainly developed for applications like self-cleaning, anti-icing or flow drag reduction. This research is a landmark example how the Nature teaches materials scientists towards functional materials.

An article entitled “Reversible switching between superhydrophobic states on a hierarchically structured surface” is published in PNAS, Proceedings of the National Academy of Sciences of the USA, and provides more in depth information about this project.

The article on the web: http://www.pnas.org/cgi/doi/10.1073/pnas.1204328109

A print quality graphic about the research available at http://media.digtator.fi/digtator/tmp/8d60ef17018948639962b423297d31c6/preview.html (Link valid until 14 July)

Watch a video: http://www.youtube.com/watch?v=AEWPIjLbrSE
Further information/interviews:

Dr. Robin Ras
robin.ras@aalto.fi
tel. +358 9 470 23169 (EET)
Aalto University School of Science, Department of Applied Physics

Johanna Lassy | Aalto University
Further information:
http://www.aalto.fi
http://www.youtube.com/watch?v=AEWPIjLbrSE

More articles from Physics and Astronomy:

nachricht Tangled magnetic fields power cosmic particle accelerators
14.12.2018 | DOE/SLAC National Accelerator Laboratory

nachricht In search of missing worlds, Hubble finds a fast evaporating exoplanet
14.12.2018 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Data use draining your battery? Tiny device to speed up memory while also saving power

14.12.2018 | Power and Electrical Engineering

Tangled magnetic fields power cosmic particle accelerators

14.12.2018 | Physics and Astronomy

In search of missing worlds, Hubble finds a fast evaporating exoplanet

14.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>