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 New material for splitting water
19.06.2018 | American Institute of Physics

nachricht Carbon nanotube optics provide optical-based quantum cryptography and quantum computing
19.06.2018 | DOE/Los Alamos National Laboratory

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: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

Im Focus: Photoexcited graphene puzzle solved

A boost for graphene-based light detectors

Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Carbon nanotube optics provide optical-based quantum cryptography and quantum computing

19.06.2018 | Physics and Astronomy

How to track and trace a protein: Nanosensors monitor intracellular deliveries

19.06.2018 | Life Sciences

New material for splitting water

19.06.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>