Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Taking self-assembly to the limits

04.12.2014

Confining tiny gold colloids inside nanoscale templates reveals how to design complex structures beyond the capabilities of conventional lithography

Gold nanoparticles smaller than 10 nanometers spontaneously self-organize in entirely new ways when trapped inside channel-like templates. A new study shows that this feature could facilitate easier nanoscale manufacturing of biosensors and plasmonic devices with intricate, high-density surface structures[1].


Researchers identify new ways of patterning gold nanoparticles with sub-10-nanometer resolution based on ‘structure transitions’ that occur when ordered states break down.

© Sergey Ilin/istock/Thinkstock

Generating surface patterns at scales of 10 nanometers and below is difficult with current technology. An international team, led by Joel Yang from the A*STAR Institute of Materials Research and Engineering in Singapore, is helping to circumvent this limitation using a technique known as ‘directed self-assembly of nanoparticles’ (DSA-n).

This approach takes spherical nanoparticles that spontaneously organize into ordered, two-dimensional films when inserted into lithographically defined templates. The templates impose geometric constraints that force the films to organize into specific nanoscale patterns.

Most patterns produced by DSA-n, however, are simple periodic arrangements. To broaden this technique’s capabilities, researchers are exploring ‘structure transitions’ that occur when template constraints become comparable to the size of the nanoparticles. At these dimensions, the small spheres can dislocate from typical periodic positions and reorient into unpredictable new geometries.

Previous studies have used real-time video microscopy to capture structure transitions in microscale colloids, but direct imaging of sub-10-nanometer particles is nearly impossible. “That’s where we came up with the idea of using templates based on channels with gradually varying widths,” says co-author Mohamed Asbahi. “With this system, we can track the self-assembly of the nanoparticles according to the space accessible to them.”

Using electron-beam lithography techniques, the team carved out an array of inward tapering trenches designed to fit 1 to 3 rows of gold nanoparticles. After depositing a monolayer of 8-nanometer particles in the template, they used scanning electron microscopy to identify any emergent width-dependent patterns. Between periodically ordered rows, the researchers saw clear evidence of transition state zones — regions where the tiny spheres buckle out of alignment and gradually take on new, triangular packing patterns.

After analyzing the transition states with computational Monte Carlo simulations, Yang and co-workers identified several dominant recurrent patterns with different geometries from typical DSA-n depositions. Because the conditions needed to generate these patterns can be predicted mathematically, the team is confident these findings can have practical surface engineering applications.

“The success of DSA-n depends on the positioning accuracy of the particles,” says Yang. “By exploiting the rich set of structural geometries that exist between ordered states, we can design templates that guide particles into complex periodic and nonperiodic structures.”

The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering

Reference:
[1] Asbahi, M., Mehraeen, S., Lim, K. T. P, Wang, F., Cao, J., Tan, M. C. & Yang, J. K. W. Template-induced structure transition in sub-10 nm self-assembling nanoparticles. Nano Letters 14, 2642–2646 (2014). 

A*STAR Research | ResearchSEA
Further information:
http://www.research.a-star.edu.sg/research/7106
http://www.researchsea.com

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 >>>