You searched for: “vapor permeable membrane”
vapor-permeable membrane (s) (noun),vapor-permeable membranes (pl)
In medicine, a very thin layer of material, usually transparent, through which oxygen and liquid can pass: "Vapor-permeable membranes may be prepared with an adhesive backing that will stick only to dry skin. This type of vapor-permeable membrane has been used in treating wounds."
A vapor-permeable membrane must be applied properly without wrinkles and changed as often as necessary to prevent an excess accumulation of fluid and bacteria under it.