Frequently Asked Questions | XCell™ Lab Controller, XCell ATF® Devices
The XCell™ Lab controller increases process control, process monitoring and throughput relative to the C24 controller. Key features include 2X device capacity, support of the XCell ATF® 1 Device (0.5-2 L), precision pumping, permeate pressure sensor capability and configurable alarms.
Precision pumping delivers precise flow rates, even at high cell densities and viscosities
Permeate pressure recording enables real time filter status and fouling monitoring
Configurable alarms notify the user of key process events
XCell ATF® 1 (SU) device support with working volumes as low as 0.5-2 for reduced development media cost
Importantly, the pumping technology has been upgraded through integration of the flow sensor into a control logic loop. The improved performance maintains a linear relationship between the observed and theoretical flow rate up to viscosity values of 6 cp, improving robustness during development and manufacturing scale-up
The XCell™ Lab Controller also represents just one component of a complete XCell ATF® Lab System that includes:
Software designed for visual process monitoring and control
Integrated flow and pressure sensors
XCell ATF® devices
Air and vacuum accessories (pump, manifold)
System engineering creates significant setup flexibility. The tablet monitor mounts both on the instrument or a lab shelf. The XCell ATF® 1 single-use device can be mounted to the edge of a benchtop or on top of a bench top. The pressure regulator and relief device can be mounted several different ways and may be located in a different room if required. Each manifold supports up to 4 controllers and each controller supports up to 2 devices, meaning a total of up to 8 XCell ATF® devices can be run on each manifold.
The XCell™ Lab ontroller supports two XCell ATF® devices (the legacy C24 controller supported only one), offering multiple benefits. The two XCell ATF® devices can be connected to either the same or different bioreactors. In either situation, using one less controller and, possibly one less bioreactor (connecting both ATF Devices to the same bioreactor), lab footprint can also be reduced.
Increased throughput: Connecting two XCell ATF® devices to two bioreactors increases throughput per controller. Execute DoE plans faster (relative to legacy C24) with more data acquired in parallel-or execute a larger DoE in the same amount of time.
Precision out-of-phase: Connecting and running two XCell ATF® devices to a single bioreactor provides an improved production scale-up model, minimizing filter oversizing during development. Use of a single controller with centralized data enables the volumes of two devices run out-of-phase to be matched through programming. In legacy systems, two XCell ATF® C24 controllers were required to control two devices connected to one bioreactor. Data on two different controllers necessitated matching flow rates through iterative manual adjustment, which was a tedious and error prone process.
A second device may also be simply connected to a bioreactor as ready-to use (and not run), providing easy transition to a second filter if the first filter fouls.
Two devices can be run in independent, in-phase or out-of-phase modes. In most cases, two devices connected to a single bioreactor will be run out-of-phase as it enables the bioreactor to remain at constant volume. Independent and in-phase mode will unlikely be used-or reserved for very niche applications.
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Mode |
ATF DUAL BOX status |
Explanation |
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ATF DUAL (synchronized) |
Independent |
Each XCell ATF® device acts without consideration of the state of the other |
|
In-Phase |
The pressure stroke for each device occurs at the same time. Similarly, the exhaust stroke for each device occurs at the same time. |
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Out-of-Phase |
The pressure stroke of the first device aligns with the exchause stroke of the second-and vice versa. The bioreactor volume remains constant. |
XCell™ Lab Controller is offered in three models: Single (S), Dual (D) and Dual System with P3 pressure sensor (D-P). A Single system (S) may be upgraded to a Dual system (D) at any time with the help of a Repligen Field Service Engineer (FSE), who performs and tests the upgrade on site. However, upgrade from an S or D model to the D-P model is not possible after purchase.
The permeate pressure sensor provides real-time filter performance and fouling characteristics. This data helps determine when a filter should be replaced and improves scale-up prediction. If development plans include scale-up, we recommend purchasing XCell™ Lab Controller Model XC-LAB-D-P.
Precision pumping delivers precise flow rates throughout the intensification process, even at high cell densities and viscosities. Flow rates set using the XCell™ Lab Controller are flow, rather than pressure, controlled. An integrated flow sensor on the A2B line (XCell ATF® device to bioreactor connection) measures flow rate and diaphragm pump displacement volume. The control algorithm analyzes flow sensor data and subsequently sets diaphragm pump and flow rate control. Flow rates are corrected to meet a user specified set point, optimizing the XCell ATF® Device backflush and filter cleaning. Matching of the user specified set point and the actual flow rate value is demonstrated by a correlation between the theoretical and observed flow rates, which is maintained up to viscosities of 6cP (see figure below). 6 cp corresponds to approximately 150-200 VCD, with some cell line dependence.