Posted on 02/15/2007 9:38:19 PM PST by LibWhacker
NEW YORK: A newly designed porous membrane, so thin that it's invisible edge-on, might revolutionise the way doctors and scientists manipulate objects as small as molecules.
The 50-atom thick filter can withstand surprisingly high pressures and may be a key to better separation of blood proteins for dialysis patients, speeding ion exchange in fuel cells and purifying air and water at the nanoscopic level.
"It's amazing, we have a material as thin as some of the molecules it's sorting, and riddled with holes - but it can withstand enough pressure to make real-world nano-filtering a practical reality," said Christopher Striemer of the University of Rochester in New York, co-creator of the membrane.
Details of the membrane, which is more than 4,000 times thinner than a human hair - thousands of times thinner than similar filters in use today - are published this week in the British journal Nature. The membrane is a 15-nanometer-thick slice of the same silicon that's used every day in computer-chip manufacturing.
Striemer developed the design while searching for a way to better understand how silicon crystalises when heated. He used such a thin piece of silicon because it would allow him to view the resulting crystal structures with an electron microscope.
As parts of the silicon contracted into crystals, Striemer noticed that holes opened up in their wake. He and colleagues at the University of Rochester realised that - since the membrane's holes were only nanometers in size - it might separate objects as small as proteins much more effectively than existing techniques.
Current molecular-level filters use a polymer-based design that is a jumble of holes and tunnels. The sizes of holes in the polymer vary greatly, and since its 'holes' are really convoluted tunnels through the material, they require much more time for proteins to pass through, and they are prone to clogging.
To test the membrane, the researchers placed a solution of two blood proteins, albumin and IgG, behind the membrane and forced it gently through the nanoscopic holes. In just over six minutes, the albumin had passed through, but the larger IgG protein was stopped. And remarkably, the 50-atom thickness could hold back 10 tonnes per square metre of pressure.
The Rochester team also found a way for the nano-filter to carry a fixed charge, effectively making the hole 'smaller' for molecules of a certain charge than for others. Their membrane can quickly and easily separate molecules by their size and their charge - a serious boon for fuel cell researchers, who wish to move only certain ions from one part of a fuel cell to another.
The Rochester group also foresees many applications for the membrane in medicine, including improved separation of blood proteins for dialysis patients and the nanoscale purification of air and water in hospitals.
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Serendipity.
Really cool technology!
If someone can find a nifty scientific use for this (I am thinking of the impact that PCR had) do I smell a Nobel in the offing?
Full Disclosure: even if not, when is their IPO? ;-)
Cheers!
Yup, I was thinking the same thing. The number of applications seems almost unlimited. For instance, as I understand the problem, the big holdup on implantable insulin pumps is a seemingly insurmountable problem with the filters clogging up. So a discovery like this could change the lives of millions of people in one fell swoop.
Could be an analogy here for smaller forms of energy/matter. I've always visualized the barrier between the quantum and pre-energy as consisting of some sort of membrane.
(Sorry for the off-topic!)
It makes great coffee, too. ;') Depending on durability and stuff, it could wind up useful for fuel cell construction, or reverse osmosis.
How about cigarette filters? Keep all those carcinagens and stuff from going down the old windpipe.
thanks for the ping
This gizmo is unlikely to have any effect on that problem. The reason filters used in the body clog up is because the body builds biofilms over them. what is needed is to find a material that is not susceptible to cell growth.
Well, except for "track-etch" filters. These use a polycarbonate film, which is "zapped" alpha particles. The ionized "tracks" through the membrane are then exposed to an "etching" chemical, which selectively attacks the ionized sites--yielding a nice little round tunnel wherever an alpha particle hits. Very consistent pore size and shape.
Ooohhhhhhhhhh... (***Big lightbulb goes on***)... Thanks for that information, WW! I didn't realize that THAT was the problem. It's a bit more complicated than I imagined.
check out their webpage: www.simpore.com
U of R. Meliora, baby!
Thanks, dude. Bookmarked.
Cheers!
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