Biomedical Engineering Reference
In-Depth Information
2D Fluid Containers
For smaller volumes, 2D bags work well, from less than 1 L to 50 L, before
they become difficult to handle. The largest 2D fluid container for bioreac-
tion is provided by GE for their Cellbag operations (Wave Bioreactor) in 1,000
L size; other suppliers such as Charter Medical can provide containers up
to 3,500 L in size. These bags are produced from two-layer films that are
welded together at their ends. The result is a flat chamber that has ports
either face welded or end welded. The choice of ports is determined by the
user and most suppliers have standard combinations that might work well
in most instances. It is important to iterate here that any custom-designed
bag or configuration would require new studies to establish the role of leach-
ables; this may not be necessary if standard off-the-shelf items are used that
have already gone into cGMP manufacturing and approval of products made
using them.
Besides their use as bioreactors, the 2D bags are utilized in a reclining or hang-
ing position as manifolds for sampling, dispensing, and holding the product.
2D Powder Bags
In some instances, it may be necessary to use bags to store powders (such as buf-
fer salts, API, and excipients): these bags have a funnel shape and are equipped
with large sanitary fittings or aseptic transfer systems, and are antistatic and
free of additives. An example of such a bag is the Thermo Scientific HyClone
Powdertrainer. Large-size powder bags are generally custom-designed.
3D Bags
The 2D bags have an interesting problem in their design: at a larger scale it
becomes difficult to maintain their integrity. The 1,000 L bag offered by GE
is recommended to be used with no more than 500 L of media; beyond that,
the seals may not hold since the weight of the fluid inside is transferred to
the seams of these bags. This becomes particularly problematic when the 2D
bags are rocked or shaken, which adds stress to the seams.
3D bags as liners in hard-walled containers obviate the problems of integ-
rity with 2D bags; today, these bags are available in sizes of 3 L to 4,000 L sizes.
The 3D design also provides additional surface to install ports with complex
functions and at both top and bottom. The 3D bags are made by welding
