A solid continuous material (film) in which microscopic pores of controlled size are created by a variety of methods.

Thin permeable film of inert polymeric material cast in such a way from a mixture of solvents so that the size, number and shape (tortuosity) of the pores is controlled. Widely used in bacterial filtration – solution sterilising – in the medical field. In multiple units they are used industrially in beverage filtration and preparation of very pure water etc. Can be in cylindrical cartridge form. Fine grades used in ultrafiltration, reverse osmosis and dialysis.

Filter used to catch bacteria to check faecal coliform levels when determining water quality.

a matrix with channels which act as a screen and retain particles larger than the filter on the surface of the membrane

Continuous matrix with pores of defined size.