SFR (Shake Flask Reader)

Oxygen and pH monitoring in shake flasks (Erlenmeyer flask), cultivation tubes, and T-flasks

SFR Shake Flask Reader in Incubator
  • Media evaluation and optimization
  • Wireless data transfer
  • Compatible with standard shakers
  • For microbial cultivations & cell culture

The SFR Shake Flask Reader monitors oxygen and pH in up to 9 Erlenmeyer flasks, cultivation tubes, or T-flasks simultaneously. It fits in nearly all standard shakers. Measurement data is transferred wirelessly via Bluetooth to your PC / notebook. The  corresponding ready-to-use vessels contain pre-calibrated sensor spots. The system monitors non-invasively through the transparent bottom of the vessels. Different types and sizes of flasks and tubes are available. Plastic, disposable flasks contain pre-calibrated oxygen and pH sensors. Glass flasks are equipped with autoclavable oxygen sensors only, and can be re-used.


  • Rapid, parallel online monitoring of up to 63 shake flasks
  • For microbial cultivation and cell culture
  • Pre-calibrated cultivation vessels are ready-to-use
  • Compatible with standard shakers
  • Glass & plastic flasks in different sizes available
  • Non-invasive measurement
  • Used in seed train & bioprocess development



Selected Probes


Screenshot: SFR Software SFRS

The SFR Software SFRS is the integrated control center for the SFR Shake Flask Reader. In addition, it offers an integrated database to show and evaluate measurements. The connection between PC and SFR is wireless. Oxygen and pH are visualized in real-time during the entire cultivation. Results are displayed in a variety of graphical representations. The advanced graphic data handling supports Design of Experiment. All measured data can be exported to Excel® or as .csv for further evaluation. Furthermore, the current measurement can be compared to stored cultivations online.


  • Enables process monitoring in shake flasks
  • Online Oxygen Uptake Rate monitoring
  • Systematic optimization of cultivation parameters
  • Compliant with FDA 21 CRF part 11
  • Supports finding feeding points
  • Facilitates optimization of harvesting strategies

The Smart Measurement Method

Illustration: SFR Measurement Method

The sensor spots are fixed at the bottom of the shake flasks, cultivation tubes, or T-flasks. The luminescence of the dyes embedded in these sensor spots is excited by the Shake Flask Reader. The luminescence lifetime is detected non-invasively through the transparent flask. The luminescence lifetime of the sensor dye depends on the oxygen partial pressure and the pH of the sample, respectively. It is converted to oxygen and pH values by the software using the provided calibration data.

Examples for Applications

Graph: O2 and pH Monitoring in Suspension-Adapted CHO Cell Culture
Process Monitoring in Suspension-Adapted CHO Cell Cultures

The online measurement of dissolved oxygen concentration and pH in shaken bioreactors paves the way for proper scale down activities from bench-top stirred-tanks to smaller scales. Adjustment of shaking speed as a function of pO2 is now possible avoiding possible oxygen limitations at high cell densities. Even a simple pH readjustment by tuning the pCO2 in the incubator is feasible to optimize the output from simple experiments with shaken bioreactors.
Dr. Robert Puskeiler, Roche Diagnostics, Penzberg, Germany

Graph: Oxygen Monitoring in Yeast & E. coli Cultures
Yeast & E. coli: Ensure Enough Oxygen Supply

S. cerevisiae grows on different sugars as carbon source. While growth on glucose and fructose is mainly fermentative, growth on galactose is mainly respirative. This leads to low oxygen concentration in the shake flasks. The accurately measured oxygen indicates the need to increase rotation frequency to avoid oxygen limitation.

High oxygen demand is typical for E. coli in its exponential phase. In the cultivation shown on the left, rotation speed had to be changed twice in order to avoid oxygen limitation. In addition, changes in the metabolism can be detected by measuring DO.

Schneider et al., University of Saarland, Saarbrücken, Germany
Bioprocess Biosyst Eng., 33(5), 541 - 547, 2009

Media Optimization

SFR measurements provide insight to substrate consumption and help to determine limitations. In the example shown on the left limitation is detected after several hours.The cause of this limitation is identified by adding different substrates and substrate combinations to the media.

Also diauxic shifts can be determined by monitoring dissolved oxygen concentration in the culture. While the bacteria change the metabolic pathways for consuming another substrate their oxygen consumption is reduced, which can be observed in a rise of oxygen concentration in the culture medium. The following drop in oxygen concentration indicates that the bacteria passed over to consume the other substrate, and their oxygen demand rises again.

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Technical Data

Please click to enlarge.

Calibration Data