Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Nanopores make sterile filtration more reliable

This mechanically stabilized nanoporous filter membrane exhibits a regular pore structure. At the same time, the pore size distribution is very tight and even. (© Fraunhofer IWM)
This mechanically stabilized nanoporous filter membrane exhibits a regular pore structure. At the same time, the pore size distribution is very tight and even. (© Fraunhofer IWM)

Abstract:
Researchers at the Fraunhofer Institute for Mechanics of Materials IWM in Halle, Germany, have created a new generation of filtration membranes

Nanopores make sterile filtration more reliable

Halle, Germany | Posted on July 1st, 2010

Irregular pores, low flow rates: The plastic membrane filters used in sterile filtration do not always ensure that conditions are really sterile. Filter membranes of aluminum oxide are more reliable - the size of the nanopores can be determined with precision. Even the smallest viruses cannot pass through the membrane.

The good ones are kept, the bad ones done away with - that, in a nutshell, is the principle behind sterile filtration: A filtration membrane frees liquids of unwanted particles and germs. Nothing larger than the filter's pores, only a few ten-thousandths of a millimeter in diameter, can pass through. Conventional membranes, usually made of plastic, come with limitations: Their pores are not evenly distributed and are occasionally too wide - and particles slip through after all. Conventional filtration membranes also have virtually no way of stopping viruses: Because most viruses are smaller than the pores, this technology offers no way to filter them out.

Now, researchers at the Fraunhofer Institute for Mechanics of Materials IWM in Halle, Germany, have created a new generation of filtration membranes: They developed ceramic membranes with a uniform pore structure and a very tight and even pore size distribution. "Compared to the ceramic membranes we have seen previously, they offer better mechanical stability and considerably higher flow rates. As a result, for the first time they are also able to replace polymer membranes", notes Annika Thormann, project manager at IWM. These membranes guarantee much more reliable filtration results than polymer membranes do. Electron microscope images of the membranes prove: The pores are regularly aligned alongside one another like the honeycombs in a beehive, one identical to the next.

To produce such filtration membranes, what is required first is the right raw material: "We use highly pure aluminum that we mold to the desired shape using extrusion equipment and thermomechanical structuring", Thormann explains. But just how can you create tiny pores on an aluminum plate with such precision? "A chemical reaction does the job", Thormann says. The molded aluminum part is placed in an acid bath where anodic oxidation takes place. An oxide layer just a few microns thick forms on the surface during electrolysis. "Tiny pores form in the aluminum during oxidation," Thormann explains. These nanopores are honeycomb-shaped, vertical to the surface, and are arrayed parallel to one another. "To set the pore size, we have to keep the voltage and the concentration of the acid stable", Thormann notes. The thickness of the nanoporous layer - and hence the flow rate of the membrane itself - can be fine-tuned as well via the duration of the oxidation process. In the end, the only step remaining is to open up the pores. This step is accomplished with chemical etching to remove unneeded residual aluminum.

The result: High-precision filtration membranes with a high porosity level. "We can vary pore diameters between 15 and 450 nanometers", says Thormann. At 15 nanometers, even the smallest viruses don't stand a chance of slipping through. The new filtration membranes are particularly beneficial to biotechnology. Aside from use of the filtration properties to produce sterile media the membranes can also facilitate tissue engineering - the cultivation of artificial tissue - thanks to their high porosity.

####

For more information, please click here

Contacts:
Annika Thormann
Fraunhofer Institute for Mechanics of Materials, Halle facilities
Walter-Hülse-Str. 1
06120 Halle (Saale)
Phone +49 345 5589-281
Fax +49 345 5589-101

Copyright © Fraunhofer-Gesellschaft

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Future electronic components to be printed like newspapers July 20th, 2018

The relationship between charge density waves and superconductivity? It's complicated July 19th, 2018

Sirrus's Issued Patent Portfolio Continues To Accelerate July 18th, 2018

FEFU scientists reported on toxicity of carbon and silicon nanotubes and carbon nanofibers: Nanoparticles with a wide range of applying, including medicine, damage cells of microalgae Heterosigma akashivo badly. July 18th, 2018

Discoveries

Future electronic components to be printed like newspapers July 20th, 2018

The relationship between charge density waves and superconductivity? It's complicated July 19th, 2018

FEFU scientists reported on toxicity of carbon and silicon nanotubes and carbon nanofibers: Nanoparticles with a wide range of applying, including medicine, damage cells of microalgae Heterosigma akashivo badly. July 18th, 2018

In borophene, boundaries are no barrier: Rice U., Northwestern researchers make and test atom-thick boron's unique domains July 17th, 2018

Announcements

Future electronic components to be printed like newspapers July 20th, 2018

The relationship between charge density waves and superconductivity? It's complicated July 19th, 2018

Sirrus's Issued Patent Portfolio Continues To Accelerate July 18th, 2018

FEFU scientists reported on toxicity of carbon and silicon nanotubes and carbon nanofibers: Nanoparticles with a wide range of applying, including medicine, damage cells of microalgae Heterosigma akashivo badly. July 18th, 2018

Nanobiotechnology

UMBC researchers develop nanoparticles to reduce internal bleeding caused by blast trauma July 13th, 2018

Researchers identify cost-cutting option in treating nail fungus with nanotechnology: GW researcher Adam Friedman, M.D., studied the potential use of nitric oxide-releasing nanoparticles to improve onychomycosis treatment July 11th, 2018

New sensor technology enables super-sensitive live monitoring of human biomolecules July 3rd, 2018

Arrowhead Presents New Clinical Data on ARO-AAT at Alpha-1 National Education Conference July 1st, 2018

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project