PTFE is certainly the most hydrophobic material it has no water adsorption and has the best thermal and mechanical strength, which is needed by a filter membrane. PTFE filter membranes produced by a stretching process under specific temperature conditions yields a highly porous but also mechanically resistant filter membrane. Due to the stretching process, the membrane experiences a certain amount of mechanical and thermal stress, which gives it stability. PTFE filter membranes are used in all kinds of filtration including air and liquid. PTFE filter membranes can capture particles and bacteria as small as 0.2 micron and can give for 100% sterility in air and gas filtration under all conditions, with throughput significantly greater than that of conventional filter membranes and they maintain that capability even through repeated sterilizations.