This is a simplified animation to explain what is happening inside an ATF System when attached to a reactor. It shows a traditional steel reactor with a connection using two bivalves to enable a re-sterilisable connection. However, single use bioreactors are just as easy to connect up to, using single use connectors such as Pall’s Kleenpack or GE’s ReadyMate.

1. Pressurized air flows into the bottom of the ATF pump
2. The air pressure and flow forces the diaphragm gently up, creating a fast flow of cells and media up through the system
3. There is rapid flow through the fibers, with a filtrate outflow showing on the right (for harvest, clarification, concentration etc.)
4. The flow of media and cells continues through the system and into the bioreactor
5. The system then reverses: air is exhausted through the pump bottom
6. The diaphragm moves down creating a rapid flow from the reactor through ATF System, ready for the next cycle.
7. The cycle repeats approximately every 5 seconds

A unique feature of the ATF System action is its inherent ability to reduce filter fouling. The combination of a reversible flow through the filter with alternating high and low pressure cycles results not only in efficient tangential flow but also in significant trans-membrane fluxes with back-flushing action on each cycle. While the back-flushing volumes may be small it is sufficient to keep the filter from fouling even at very high cell concentration, greater than 200 x106 cells/ml in some cases. The ATF System action allows the use of smaller filters than would otherwise be expected.