Compact Gassing Modules Save Space and Simplify Design of Benchtop Bioreactors

Gas Control in Stirred Bioreactors

Gas control is critical for maintaining optimal conditions for cell growth in bioreactors. In most stirred bioreactors, gas is controlled through a combination of sparging (sub-surface) and headspace sweeping (super-surface). Gases such as oxygen and nitrogen assist cell culture growth while removal of carbon dioxide prevents toxic buildup.

Sparging, the introduction of gases directly into the medium, creates bubbles that dissolve gases into the liquid. Although a theoretically simple process, many variables related to sparging control are essential to optimizing mass transfer. The optimal levels can vary greatly between bioreactors and culture types.

Key Mass Transfer Factors Influenced by Sparging

  • Bubble Size: Smaller bubbles increase the surface area-to-volume ratio, allowing more oxygen to dissolve into the medium, which is crucial for aerobic cell culture growth as it ensures a steady supply of oxygen.
  • Bubble formation: Factors such as gas flow rate, sparger design, and liquid viscosity influence how bubbles form into the liquid, impacting bubble size and rate of dissolution.
  • Agitator Type: Agitators mix the bubbles into the medium even further. The size and speed of an agitator affects the bubble pattern in the reactor, which influences the gas dissolution. Too much agitation can cause shear on the cells, destroying cultures.

While sparging is essential for gas introduction, the effectiveness of this process is heavily influenced by the precise control of gas flow rates.

The Role of Flow Control

Flow rates of gas into stirred bioreactors are essential to performance, as they directly impact bubble formation and size. Flow rates must also be carefully controlled, or they will provide excessive turbulence, which will harm the cells. Lower flow rates are advantageous for benchtop bioreactors as they optimize gas distribution by creating small bubbles, without excessive turbulence.

Traditional gas control systems can be bulky and complex, posing challenges in space-constrained laboratories. Compact mass flow gassing modules offer a solution by providing precise gas control while saving space and simplifying design.

BASIS™ Compact Gassing Modules

Alicat Scientific™, a leader in flow control technology, has developed custom BASIS gassing modules to address specific needs in biotechnology. This streamlined, efficient solution not only simplifies the control of flow rates but also optimizes them, providing highly repetitive and fast gas control. By incorporating a custom-engineered BASIS gassing module, laboratories can improve space efficiency and performance, making it a valuable addition to bioreactor setups.

Miniature Gassing Module with BASIS mass flow controllers from Alicat Scientific for OEM applications.

Advantages of BASIS Gassing Modules

  • Switch Between Multiple Gases: The ability to switch between nine gases, including air, N2, O2, and CO2, provides versatility for various applications.
  • 1,000:1 turndown: Control a wider range of flows than other small flow controllers.
  • Sophisticated scripts: Run control scripts using fast, robust ASCII command set.
  • Space Efficiency: Small footprint for efficient use of space.
  • Simplified Engineering: Integrated design reduces setup and maintenance complexity.
  • Enhanced Performance: Reliable and consistent gas delivery improves overall bioreactor productivity.

Compact gassing modules offer a streamlined, efficient solution for gas control in bioreactors. By simplifying engineering and saving space, these gassing modules enhance bioreactor performance and productivity, making them invaluable tools for the biotech industry.

Contact Alicat Scientific to explore how BASIS can transform your operations.


This article was originally published in Fluid Handing Pro’s Flow Control and Measurement.

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