US Patent 8048371 Fail-closed adaptive membrane structure

Porous adaptive membrane structures having movable membranes are provided. The structures can be made to change their gas, liquid and/or particulate permeability in response to surrounding environmental conditions. Applications includes protective apparel that is comfortable to wear wherein the level of protection provided is based on conditions in the environment. Hence, the protective apparel is highly breathable and comfortable in a non-hazardous environment but impermeable or only semipermeable in a hazardous environment.