Three-stage manufacturing process
Gold-coated track-etched filters are made in a three stage process. In the first stage, charged particles are fired at polycarbonate foil (which is still pore-free) in a reactor. In the second stage, the traces produced by the particles are enlarged into tunnel-shaped pores with an etching solution. The width of the pores is dictated by the concentration of the etching solution and time and can be produced individually depending on the application. In the last stage, the membrane is sputtered with gold. The result is a very thinly coated membrane foil that allows almost 100 per cent surface filtration.
Analyses according to globally recognized standards and guidelines
Polycarbonate track-etched filters are especially suitable for particle analysis. This includes the testing of indoor and outdoor air to measure levels of inorganic fibers such as asbestos in accordance with VDI guidelines 3492 and 3861 and with ISO 14966. It is also easy to measure levels of dusts and powders in accordance with BIA 7487 by using track-etched membranes. i3 TrackPor membranes are also used for asbestos analysis of plaster, fillers and paints on house interiors and exteriors in accordance with VDI 3866 and 3877.
High contrast and optimum conductivity
Because of the even surface and the tunnel-shaped pores, the particles being analyzed remain on the smooth surface of i3 TrackPor membranes and can thus be examined microscopically. The membranes are coated with gold on both sides and conform to current VDI standards. The gold layer on the receiving side of the filter (shiny side) is about 40 nm thick while the gold layer on the matt side is about 20 nm thick and serves to stabilize the filter during the measurement process. The gold layer protects the polycarbonate filter during evaluations with a scanning electron microscope (SEM), increasing the contrast and providing optimal conductivity.
Simple and reliable asbestos analysis
i3 TrackPor track-etched membranes are also employed in the ready-to-use i3 TrackPor M single-use monitoring device for asbestos analysis. In accordance with VDI guideline 3492, the monitoring device is connected to a sampling device. The air is sucked through the monitoring device for a few hours so that the particles settle on the gold-coated membrane. After measurement has been carried out, the gold membrane is removed in the laboratory and the dust present on it is burnt. Using a scanning electron microscope, the asbestos fibers are counted and the fiber types found are then identified and classified using energy-dispersive x-ray analysis (EDXA).
i3 TrackPor membranes are available in various different diameters and pore sizes. The application areas include:
- Particle analysis using SEM and EDX
- Counting nanoparticles
- Testing for technical cleanliness
- Identification of fibrous particles such as asbestos in accordance with:
- VDI guideline 3492 – in indoor air
- VDI guideline 3877 – on surfaces
- VDI guideline 3866 – in technical products
- VDI guideline 3861 – in flowing pure gas
- BIA procedure 7487 - asbestos in powders and dust
- ISO 14966 – fibers in ambient air