I'm not sure of the dimensions that you are seeking.  Sterlitech carries a pretty good assortment of disc membranes for testing (http://www.sterlitech.com/filters/membrane-disc-filters.html), but I am not sure of the thickness.  I suspect that a membrane material that thin will be attached to a supportive layer of material.

You are right Scott Waisner, but I required very thin (

I made it by myself. PVDF fiber nonwoven membrane.  

Hu Chaoyang

Can you tell me more about PVDF membrane you made (specially porosity, thickness)

Check out these links.  Hopefully this is helpful.

Phil

Nanofiber-based (15-30 micron thickness): http://www.hiroseamerica.com/products/nanofiber-overlaid-nonwovens/

Expanded PTFE membranes (5 micron - 250 micron thickness): http://www2.donaldson.com/tetratex/en-uk/pages/products/donaldson-eptfe-films-laminates.aspx

Gore (makers of Gore-Tex) also have some nice ePTFE membranes for filtration: http://www.gore.com/en_xx/products/filtration/microelectronic/upw/ultrapure-membrane-technology.html

Dupont Teijin films makes PET and PEN films below 6 µm (1/4 mil). For the thinnest films, look into Mylar and Teonex for capacitors, some of which go down to 0.9µm.

http://europe.dupontteijinfilms.com/media/2274/dtf_product_brochure_capacitors_2014.pdf