Shape Matters – An Innovative Design for Single-use Bioreactors

For many years cylindrical stainless steel tanks have been used in biopharmaceutical production. The primary reason for the cylindrical shape was that it provided the mechanical stability required for high-pressure steam sterilization.

In recent years single-use systems have become more widely adopted for many reasons including: reduced cleaning and validation time, improvements in cell culture productivity requiring less manufacturing volume, and flexibility. As single-use bioreactor vessels were developed, they adopted the same cylindrical shape as their stainless steel counterparts.

However, Pall recently traded the traditional geometry for the cube shape Allegro™ STR single-use bioreactor line. Their innovative cube shape offers unique features not possible in a cylindrical design.

Innovative Design

In designing the Allegro STR line of single-use bioreactors, Pall started by applying systems engineering principles to inform the design approach that they felt would best meet biomanufacturing demands. With one of the advantages of single-use being the elimination of steam and clean in place procedures, the designers were free to change the shape from the traditional cylinder.

In addition, Pall had a successful history of using cubical single-use containers for storage, fluid transportation and mixing. Pall had significant experience in manufacturing and validation of these cubical biocontainers.

Key Advantages of the Allegro STR single-use bioreactors

Smaller Footprint

With the lower height to width ratio than a cylindrical vessel at a similar scale, larger volumes can be accommodated in the same footprint; for example, a 2,000 liter bioreactor system can be installed in a facility under 3m high.

Improved Culture Conditions

The Allegro STR bioreactor family has a direct bottom-driven impellor, which permits power inputs up to 0.25 W/kg, thus enabling high oxygen transfer rates and short mixing times. In validating the new design, Pall performed extensive studies using computational fluid dynamics (CFD) to show that there are no dead zones and 95% homogenization can be reached within less than 16 seconds (full impeller speed at up to 2000 L working volume).

Easier installation and operation

The gamma irradiated, square shaped biocontainer provides a more robust single-use bioreactor – product integrity is maintained, as the system is easier to package and protect during transportation. The square design, with distinct faces, is simpler to unfold and install, with less human intervention and reduced risk of error than with traditional cylindrical single-use bioreactors.

Key operation features include:

  • A single bottom-mounted impeller allows the biocontainer to be packed into a compact unit that can be placed directly into the hardware with minimal operator manipulation
  • Installation and inflation of the biocontainer is achieved in < 30 minutes through a guided sequence via the Human Machine Interface (HMI)
  • The low aspect ratio of the systems minimize the operations that have to be performed at height
  • Automatic biocontainer deflation speeds up turnaround time, minimizes operator activity and reduces the overall volume of waste for disposal

You can read more about the bioprocess, mechanical, production, control engineering and ergonomic aspects of the PALL Allegro STR bioreactor family in the following article – Design and Performance of Single-Use, Stirred Tank Bioreactors

Learn how the Allegro STR single-use bioreactors are an ergonomically-designed and operationally-intuitive bioreactor. Please see following video:

Pall and Allegro are trademarks of Pall Corporation

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