How to optimize the performance of bioreactors using mass controllers.

We are currently in a race against the clock in the development of new vaccines against infectious diseases. In the Biopharmaceutical world, the efficiency and technological productivity of bioreactors is a key point in this development.

Bioreactors create the optimal environmental conditions of temperature, nutrient concentration, pH, dissolved oxygen,… for fermentation and / or production of cell cultures. The higher the yield of the bioreactor cell culture, the greater the probability of obtaining a quality product: Vaccine, drug….

Performance of a bioreactor

There are two fundamental variables that directly influence the operation of a bioreactor, dissolved O2 and pH. Both are directly dependent on accurate and reliable gas flow control.

The amount of O2 dissolved in the medium must be reduced or increased by precise injection of O2 or N2. Given that O2 is relatively poorly soluble in water, the amount of air that allows maintaining an O2 concentration that favors the performance of the bioreactor is usually added constantly.

The pH of the medium is usually regulated by the addition of acids and / or bases. In the case of cell cultures, liquid acids could damage cells, instead acidification is usually done by adding CO2.

For CO2 flow adjustment, bioreactor manufacturers have traditionally used manual valve rotameters. These systems have obvious limitations, so the current trend is to replace them with digital mass flow controllers.

Advantages of mass controllers.

First of all, both rotameters and differential pressure controllers are volumetric systems. Therefore, small variations in Pressure (P) and Tempreature (T) translate into a significant error in the flow measurement. Mass instruments, unlike the previous ones, are totally independent of P and T, and do not require any compensation.

On the other hand, it is evident that an automatic flow control is critical for a good operation of the bioreactor. Despite the economic advantages of rotameters, they do not have any output signal that allows them to automatically handle the variations in the conditions required for optimal operation of a bioreactor.

Other important aspects are the size of the mass controller, and its versatility. For example, the ability to handle different gases (O2 and N2) with the same equipment is always an interesting feature.

Finally, in clean room environments, contamination phenomena can spoil crop batches, with the consequent loss of productivity. Using equipment that is less sensitive to contamination will reduce this risk.

We can conclude that the Smart-Trak mass flow controllers (MFC) from the American company Sierra Instruments can perfectly perform this function.


Most important characteristics of the SMART-Track:

  1. Thermal dispersion measurement technology gives a direct measurement of the mass flow, unaffected by variations in P and T
  2. Its capillary type measurement system provides great measurement linearity regardless of the gas measured. Thanks to its digital electronics, the equipment is delivered calibrated for 10 different gases
  3. “Superior” measurement features; accuracy +/- 1% full scale (for all gases), repeatability +/- 0.2% f.e., and turndown of 50: 1
  4. It incorporates a direct-acting, frictionless, automatic control valve for fast and stable gas flow adjustment between 2 and 100% of the equipment range.
  5. Compact in size, with high quality 316 stainless steel measuring body, and multiple types of process connection available


For more information, you can contact MATELCO, SA.

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