Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. Space Industry and Business News .




TECH SPACE
Thinnest feasible membrane produced
by Staff Writers
Zurich, Switzerland (SPX) Apr 28, 2014


Artist's rendering of the two-layered graphene membrane (grey honeycomb structure) with molecules (blue) being able - as a function of their size - to pass the pores. Image courtesy Ben Newton and ETH Zurich.

Researchers have produced a stable porous membrane that is thinner than a nanometre. This is a 100,000 times thinner than the diameter of a human hair.

The membrane consists of two layers of the much exalted "super material" graphene, a two-dimensional film made of carbon atoms, on which the team of researchers, led by Professor Hyung Gyu Park at the Department of Mechanical and Process Engineering at ETH Zurich, etched tiny pores of a precisely defined size.

The membrane can thus permeate tiny molecules. Larger molecules or particles, on the other hand, can pass only slowly or not at all.

"With a thickness of just two carbon atoms, this is the thinnest porous membrane that is technologically possible to make," says PhD student Jakob Buchheim, one of the two lead authors of the study, which was conducted by ETH-Zurich researchers in collaboration with scientists from Empa and a research laboratory of LG Electronics. The study has just been published in journal Science.

The ultra-thin graphene membrane may one day be used for a range of different purposes, including waterproof clothing.

"Our membrane is not only very light and flexible, but it is also a thousand fold more breathable than Goretex," says Kemal Celebi, a postdoc in Park's laboratory and also one of the lead authors of the study. The membrane could also potentially be used to separate gaseous mixtures into their constituent parts or to filter impurities from fluids.

The researchers were able to demonstrate for the first time that graphene membranes could be suitable for water filtration. The researchers also see a potential use for the membrane in devices used for the accurate measurement of gas and fluid flow rates that are crucial to unveiling the physics around mass transfer at nanoscales and separation of chemical mixtures.

Breakthrough in nanofabrication
The researchers not only succeeded in producing the starting material, a double-layer graphene film with a high level of purity, but they also mastered a technique called focused ion beam milling to etch pores into the graphene film.

In this process, which is also used in the production of semiconductors, a beam of helium or gallium ions is controlled with a high level of precision in order to etch away material.

The researchers were able to etch pores of a specified number and size into the graphene with unprecedented precision. This process, which could easily take days to complete, took only a few hours in the current work. "This is a breakthrough that enables the nanofabrication of the porous graphene membranes," explains Ivan Shorubalko, a scientist at Empa that also contributed to the study.

In order to achieve this level of precision, the researchers had to work with double-layer graphene.

"It wouldn't have been possible for this method to create such a membrane with only one layer because graphene in practice isn't perfect," says Park.

The material can exhibit certain irregularities in the honeycomb structure of the carbon atoms. Now and again, individual atoms are missing from the structure, which not only impairs the stability of the material but also makes it impossible to etch a high-precision pore onto such a defect. The researchers solved this problem by laying two graphene layers on top of each other. The probability of two defects settling directly above one another is extremely low, explains Park.

Fastest possible filtration
A key advantage of the tiny dimensions is that the thinner a membrane, the lower its permeation resistance. The lower the resistance, the higher the energy-efficiency of the filtration process. "With such atomically thin membranes we can reach maximal permeation for a membrane of a given pore size and we believe that they allow the fastest feasible rate of permeation," says Celebi.

However, before these applications are ready for use on an industrial scale or for the production of functional waterproof clothing, the manufacturing process needs to be further developed.

To investigate the fundamental science, the researchers worked with tiny pieces of membrane with a surface area of less than one hundredth of a square millimetre. Objectives from now on will be to produce larger membrane surfaces and impose various filtering mechanisms.

Celebi K, Buchheim J, Wyss RM, Droudian A, Gasser P, Shorubako I, Kye JI, Lee C, Park HG: Ultimate Permeation Across Atomically Thin Porous Graphene. Science, 2014, 344: 289-344, doi: 10.1126/science.1249097

.


Related Links
ETH Zurich
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





TECH SPACE
Repeated Self-Healing Now Possible in Composite Materials
Urbana IL (SPX) Apr 22, 2014
Internal damage in fiber-reinforced composites, materials used in structures of modern airplanes and automobiles, is difficult to detect and nearly impossible to repair by conventional methods. A small, internal crack can quickly develop into irreversible damage from delamination, a process in which the layers separate. This remains one of the most significant factors limiting more widespread us ... read more


TECH SPACE
Thinnest feasible membrane produced

When things get glassy, molecules go fractal

How Productive are the Ore Factories in the Deep Sea?

Vacuum Ultraviolet Lamp of the Future Created in Japan

TECH SPACE
Radio terminals for MUOS satellite communications have testing facility

High Gain Amplifiers for Commercial and Military Radar Released by Pasternack

Tactical radios tested with MUOS waveform

Harris supplying more communications terminals to Navy

TECH SPACE
Vega for third Arianespace mission, carrying Earth observation spacecraft

It's a "go" for Arianespace's Vega launch with Kazakhstan's first Earth observation satellite

Russia sends two satellites into space

SpaceX sues US Air Force over satellite contracts

TECH SPACE
Glonass Failure Caused by Faulty Software

Homegrown high-precision positioning system put to use

Russia eyes building Glonass stations in 36 countries

Turn your satnav ideas into business

TECH SPACE
Air Force enhancing mission capability to its remotely piloted aircraft

Northrop Grumman Awarded US Navy Contract for Next-Gen Mission Computer

Middle East country getting air combat training support from Cubic

Alenia Aermacchi, ATK MC-27J in flight test

TECH SPACE
Progress made in developing nanoscale electronics

Piezotronics and piezo-phototronics leading to unprecedented active electronics and optoelectronics

Superconducting Qubit Array Points the Way to Quantum Computers

Stanford bioengineers create circuit board modeled on the human brain

TECH SPACE
When next Earth's magnetic field reverse begins and what consequences for mankind will it have?

Ball Aerospace Moving Ahead on TEMPO and GEMS Air Quality Sensors

UV-radiation data to help ecological research

EO May Increase Survival Of 'Uncontacted' Tribes

TECH SPACE
China toughens environment law to target polluters

The result of slow degradation

MEPs back plans to slash use of plastic shopping bags

Oil company blamed for toxic tap water in China: Xinhua




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.