Porous membrane

[prex]

I'm looking for a membrane that would be porous to air in one direction end tight in the opposite one.
This would ideally be like a plastic sheet for polyethylene bags, but anything working as above would be interesting.
Any ideas?
prex
motori@xcalcsREMOVE.com

http://www.xcalcs.com

Online tools for structural design

 

[nbucska]

Let's suppose you have this mambrane.

You divide a tank into two parts by this membrane which is
porous from left to right.

The molecules with higher than average velocity would
go into the right side until the average velocity on the
right would become equal to the maximum velocity on the left.

So basically you invented a limited version of Maxwell-s demon. <nbucska@pcperipherals.com>

 

[prex]

This is true if you limit your analysis to a 'static' porous membrane, or, better said, to a system with no energy input from outside, that of course can't be one way.
What I'm thinking of, is something that works like a check valve, that lets a fluid go in one direction only and shuts down as soon as pressure on downstream side becomes higher than upstream.
This principle may be implemented on any type of air tight film by putting somewhere a small check valve, using one of the available principles for such type of device (a sphere or disk moving back and forth, a flexible lip): I was just wondering if something of this kind might be done at a microscopic level.
prex
motori@xcalcsREMOVE.com

http://www.xcalcs.com

Online tools for structural design

 

[nbucska]

look up <Maxwell's demon&quot; on e.g. <

http://www.yahoo.com>

<nbucska@pcperipherals.com>

 

[jonralph]

Not sure exactly of your application but what about the likes of Gore Tex or even human skin? Not that I am implying anything Ed Gein!

So why can't you use a conventional check valve?

 

[Salomonas]

Theoretically, a layer of nano check valves could be designed on any porous membrane. I don't think anybody has that function figured out yet, much less produced for a commercial use. I'd try searching in advanced materials and membrane research for leads.