Can you explain in a bit more detail how the internal floating filter works? It seems like an efficient set-up.

Answer

The floating filter is used to retain cells in the Cellbag Bioreactor during perfusion cultivation or medium exchange. It consists of filter material with a nominal pore size of 7 µm, which is laminated to a plastic film covering the back of the filter. Due to the lower density, the filter floats on top of the cultivation medium. It is connected to the wall of the Cellbag Bioreactor via a harvest tube. The outside port of this harvest tube ends in a Luer connector allowing to attach pump tubing and harvest vessel. Operating a peristaltic pump in the harvest line will create suction and draw liquid through the filter into the harvest vessel. The cells are retained by the filter, the surface of which is largely cleared due to its movement across the culture surface. In this setup no recirculation loop is required, which makes the setup easier. Additionally the cells remain in the controlled environment of the bioreactor throughout the cultivation.
The filter comes in two different sizes, a smaller one for Cellbag Bioreactors with 1 and 5 liter working volumes and a larger one for 10 and 25 liter working volumes.