Track-etched membranes

Track-etched membranes are very thin but highly controlled membranes traditionally used for high-specification filtration in laboratory applications. Track-etched membranes are useful for the filtration of particles ranging from approximately 0.1 to 10 µm in diameter. Manufacturing starts with a thin film of polycarbonate or polyethylene. The film is exposed to ionizing radiation or ion bombardment, which produces tracks in the film where the polymer strands have been chemically broken. The polymer strands are then digested away using controlled chemical conditions. The length of the chemical treatment determines the diameter of the pores. The pores have very regular geometries and extend as cylinders from one face of the film to the other. While track-etched membranes are typically used in the filtration of samples prior to critical processes such as high-pressure liquid chromatography (HPLC), there is an increasing number of other operations that can be performed as a result of the unique properties found in track-etched membranes.

1. Start with a thin, plastic film.

2. Expose the membrane to ionizing radiation.

3,  Chemically treat the membrane to etch the polymer away along the tracks. 

The PC membrane in the syringe filters is usually produced by the track-etched method.