XCell™ ATF Cell Retention System

The XCell™ ATF System integrates a diaphragm pump, a stainless steel housing, and a single-use hollow fiber filter cartridge. 

  • Connect the XCell™ ATF System to a bioreactor. 
  • Pressurized air flows into the bottom of the ATF pump.
  • The air pressure forces the diaphragm gently up, displacing liquid and creating a fast flow of cell culture media across the surface of the hollow fiber filter.
  • There is rapid flow of media through the filter fibers, with a cell-free filtrate being generated.
  • The cell culture fluid remaining on the upstream side of the hollow fiber filter is returned back into the bioreactor.
  • The system then reverses: air is exhausted through the pump bottom.
  • The diaphragm moves down creating a rapid flow of cell culture media from the bioreactor back into the XCell™ ATF System. The system is now ready for the next cycle.
  • The cycle repeats approximately every 5 seconds.
 

Watch the video animation to see how XCell™ Alternating Tangential Flow (ATF) technology simplifies and intensifies upstream bioprocessing.

High flow with low shear

The gentle action of the diaphragm in an XCell™ ATF System minimizes shear during pump operation. This results in separation of cells, cleaning of the filter surface and delivers extremely high cell concentrations such as 100-200x106 cells/ml in many different cell line types including CHO.

Reduced filter fouling

The combination of a  single bioreactor connection and 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. 

 

Watch the video to see the XCell™ ATF device diaphragm movement in real time.

XCell™ ATF hollow fiber filter

In XCell™ ATF systems, the alternating tangential flow sweeps the membrane surface, but in addition, a backflush occurs with each cycle because the XCell™ ATF reverses flow within the same line. This action cleans the filter while minimizing gel layer formation and  ultimately reducing fouling.

 
 
When scaling production, the XCell™ ATF Scale-up Calculator illustrates how to equalize three important parameters based on a desired small-scale or large scale model:
 
  • Flux - equalizes filtration capacity across scales
    If the bioreactor is undersized relative to the XCell™ ATF System at small scale, flux can be mimicked by recycling some filtrate back to the bioreactor.
  • XCell™ ATF flow to filtration ratio - equalizes backflush efficiency across scales, related to Transmembrane Pressure (TMP)
  • Flow per fiber - equalizes cell shear across scales
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