The present invention is directed to a filtration system including filter media that use diffusion as a method of particulate reduction that balances the contact time required for a desirable level of interception and filter performance. The filter system of the present invention includes a filter medium...http://www.google.de/patents/US7241388?utm_source=gb-gplus-sharePatent US7241388 - Means to miniaturize diffusion filters for particulate removal
