Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Magnetic Chameleons

17.03.2011
New displays that change color under the influence of magnets

Chinese researchers have created microscopic capsules that change color when a magnetic field is applied. When the capsules are collected into an array, magnetic fields can be used to create colored patterns on an extremely small scale.


Many animals use tiny physical changes at their skin or surface to alter their color. Chameleons do this by pumping slightly different amount of dye into the surface of their skins. Other animals, such as some beetles, fish and birds, have special arrays of light-reflecting cells that are moved apart very slightly by the injection or removal of a fluid, or by tiny stretching of their skin. These nanometer changes in spacing are enough to change the wavelength of light that is reflected and hence the color that we see.

Scientists have been able to replicate this effect to some extent using regular clusters of tiny spheres known as colloidal crystals. The spacing between the centres of the spheres determines the wavelength of light that is reflected and, hence the color of the crystal. Simple actions such as adding fluid (as described above) or swelling the size of the particles have been used to change the color.

If the spheres used are magnetic, then a magnetic field can be used to control the spacing between them, and, of course, the color. This phenomenon has been shown previously, but stable systems were not created and the color seen was very dependent on viewing angle.

Now, as described in the journal Advanced Functional Materials, Zhongze Gu and coworkers at the Southeast University in Nanjing have created stable droplets of particles whose color can be tuned through a wide range and which does not depend on where the viewer stands.

Their breakthrough was to encapsulate clusters of magnetic spheres in a liquid within tiny, transparent resin beads. The beads are highly uniform and could be used as individual pixels in a display. Applying different magnetic fields causes the spheres within the capsules to move further apart or closer together, resulting in different colors. The picture shows the effect of applying different magnetic fields.

Another clever idea of Gu and his team was to use automated technology to create the capsules. Uniform sizes and composition are required if such materials are to be used as displays, and this was achieved by using microfluidic techniques, where reactions occur continuously as ingredients travel along the narrow channels of a very small-scale reactor. Tuning the flow rates of various reactants easily controls the capsulesf size, shell thickness and shape.

The scientists are proud of their work and imagine that it could be adapted to be used with electronic magnetic fields, using the full potential of the tiny scale of the microcapsules and leading to gmore complex and interesting patterns.h

C. Zhu, W. Y. Xu, L. S. Chen, W. D. Zhang, H. Xu, and Z. Z. Gu, gMagnetochromatic Microcapsule Array for Displayh, Adv. Funct. Mater. 2011; DOI: 10.1002:adfm.201002296.

Contact:
Prof. Zhongze Gu
State Key Laboratory of Bioelectronics
Sipailou 2, Nanjing, P. R. China
EmailFgu@seu.edu.cn
Tel/Fax: +86-25-83795635

Carmen Teutsch | Wiley-VCH
Further information:
http://www.wiley-vch.de
http://www.lmbe.seu.edu.cn/~guzhz/English/Eindex.htm

More articles from Materials Sciences:

nachricht Flying: Efficiency thanks to Lightweight Air Nozzles
23.10.2017 | Technische Universität Chemnitz

nachricht Strange but true: Turning a material upside down can sometimes make it softer
20.10.2017 | Universitat Autonoma de Barcelona

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>