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The Cell Growth Quantifier (CGQ)

Close Up of a CGQ Sensor 
The CGQ is a sensor-based technology that offers highly parallelized, non-invasive online monitoring of biomass in shake flasks and other cultivation vessels. Our patented sensors are easy to install under the vessel and monitor the biomass through the glass wall by backscatter measurements. This enables you to follow the growth of your cultures in real time and generate profound bioprocess understanding.
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Key Facts

For a broad range of organisms

Bacteria, archaea, fungi, yeast, algae, plant cells and more

Compatible with various cultivation vessels

Shake flasks, serum bottles, Schott bottles and others

Works on all types of shakers

Compatible with any shaker and clamps as well as sticky stuff

One sensor for all shake flask sizes

Use one sensor for different shake flask sizes by applying our adapters

Highly parallelized measurements

Monitor up to 64 shake flasks in parallel on one laptop

Easy to install and use

A plug and play technology with an intuitive user interface

Close-up of CGQ base station on a tray with several 250ml shake flasks

Exemplary Applications

Growth curves for a yeast media screening
Example of an OD growth curve generated by the CGQ
Example of a CGQ growth curve for a thermophile organism

Example of a CGQ growth curve for an anaerobic organism
Example of a CGQ growth curve for plant cells
Example of a CGQ growth curve for microalgae


What does the CGQ measure?

Using an array of LEDs and photodiodes, each CGQ sensor plate can adaptively measure the backscatter intensity at different radial positions, thus accounting for a broad variety of liquid distributions in shake flask fermentations. Furthermore, the CGQ’s innovative measuring method treats the signal fluctuations as a valuable information source rather than noise.

How is scattered light used to measure biomass?

The CGQ implements the well-known technique of light scattering with light source and sensor mounted directly into the spring clamp under the shake flask. Depending on the current biomass concentration inside the flask, different amounts of light are scattered towards the sensor.

Has the CGQ technology been used in any published research?

Yes, there are several publications available:


What does the typical set-up of the CGQ look like?

Which type of flasks is the CGQ compatible with?

Can I use the CGQ with old flasks that have scratches?

As long as there are not too many or really deep scratches, even very old shake flasks can be used.

Can the CGQ be used for cultivation vessels other than shake flasks?

Yes, it can be used with serum bottles, Schott bottles, Müller + Krempel bottles and be customized to fit other formats as well.

How many flasks can I monitor in parallel?

Currently, there are two types of base stations: One for up to 8 and one for up to 16 different shake flasks. With CGQuant 8.0 you can now monitor up to four base stations simultaneously on one laptop, enabling parallel measurements with up to 64 sensor plates in total.

On which types of shaker does the CGQ work?

It is compatible with all common types of laboratory shakers (e.g. INFORS, New Brunswick, Kühner, Thermo…) and can be used with either normal spring clamps or with sticky plates/sticky stuff.

How long does it take to install the CGQ in the shaker?

On average, users take roughly five to ten minutes to install the CGQ on their shakers.

Do I need different sensor plates for each flask size?

No. By using our universal adapters you can make a sensor plate fit whatever flask size you want to use it with.


How does the CGQ transfer data to the computer?

The base station is connected to the computer via USB cable which fits through the door opening of every shaker.

Bioprocess Conditions

What is the optimal filling volume of a shake flask when using the CGQ?

Measurement Range  Filling Volume
Optimal 10 – 15 % of total flask volume
Good 5 – 25 % of total flask volume
Acceptable 2 – 30 % of total flask volume
Extended < 2 % and > 30 % of total flask volume

At which temperatures can I use the CGQ?

The CGQ can be used between 10 °C and 80 °C.

Which are the minimum and maximum shaking speeds I can use the CGQ with?

It depends on the size of the shake flask and the filling volume, but the technology is optimized for high shaking speeds. The CGQ provided valuable results at 350 rpm (3 % filling volume) for example, but also at 80 rpm.

Do the flasks need to be covered at all times?

Due to the external light compensation featured in CGQuant 8.0 and newer versions, shake flasks no longer need to be covered at all times. However, covers can still be used whenever particularly accurate biomass measurements are required. Please contact us if you are unsure whether covers would be recommended for your specific applications.

For which cell types has the CGQ been tested?

The CGQ can be used for many different types of shake flask cultures. Currently, we are evaluating if the CGQ is applicable for monitoring human, animal and insect cells.

Bacteria Yeast
Escherichia coli, Corynebacterium glutamicum, Bacillus subtilis, Pseudomonas putida, Gluconobacter oxydans, Lactobacillus plantarum, Actinobacillus pleuropneunomiae, Klebsiella pneumoniae, Staphylococcus aureus, Vibrio cholerae, Vibrio natriegens, Chromobacterium violaceum, Blautia producta, Hungatella hathewayi, Prevotella copri Saccharomyces cerevisiae, Schizosaccharomyces pombe, Pichia pastoris, Yarrowia lipolytica,  Kluyveromyces lactis, Hansenula polymorpha
Archaea Filamentous organisms
Sulfolobus acidocaldarius, Haloferax volcanii Streptomyces venezuelae, Streptomyces acidiscabies, Aspergillus niger, Aspergillus nidulans, Ustilago maydis
Phototrophic organisms Anaerobic organisms
Chlorella vulgaris, Scenedesmus obliquus (green algae), Synechococcus elongatus PCC 7942 (cyanobacteria), Nicotiana tabacum BY-2 (plant cells) Clostridium ljungdahlii, Clostridium aectobutylicum, Clostridium difficile, Acetobacterium woodii

Can I use the CGQ with phototrophic organisms?

With covers being rendered unnecessary in CGQuant 8.0 and newer, biomass monitoring with the CGQ is now possible in phototrophic cultures. Additionally, we are able to adapt the CGQ to your bioprocess conditions by customizing our device’s LEDs to a wavelength of your choice.

For which types of applications has the CGQ been used?

The CGQ has been used for a broad range of applications, such as:

  • Growth characterization
  • Bioprocess optimization
  • Screening of strains/mutants, media and bioprocess conditions (shaking speed, filling volume, temperature etc.)
  • Growth phase-based induction of protein expression
  • Phage assays
  • Non-invasive monitoring of anaerobic, thermophilic as well as phototrophic organisms
  • Toxicity tests
  • Reproducible production of competent cells
  • Up-scaling
  • Quality control

OD Measurements

Can I measure OD / cell dry weight / cell count etc. by using the CGQ?

The CGQ backscatter signal shows a strictly monotonic non-linear correlation with OD, cell dry weight, cell count and similar. For measuring these parameters in real time, users can create a calibration curve with the CGQuant software by providing single-point values to the CGQ.

Can I use one calibration for all my experiments?

After a successful calibration, the same file can be used if the bioprocess conditions do not drastically change. You can also apply a suitable calibration file to old experiments, so you can switch from backscatter to a different parameter.

What is the OD measurement range?

Usually, the OD600 measurement range lies between 0.2 and >50. However, OD ranges greatly depend on the organism, cultivation medium and bioprocess conditions.


What are the PC/Laptop requirements to work with the CGQ?

OS Windows 7 or newer
Processor Dual Core @ 2 GHz/core
Memory 4 GB RAM
Hard Drive 1 GB free space

Is the software available for MacOS?

No, the software is currently only available for Windows.

How many software licenses are included with the CGQ platform?

Unlimited. You can install the software on as many PCs/Laptops as you need.

Can anyone use the software or will it require special training?

As the CGQuant software was specifically designed to be intuitive and is always optimized based on user feedback, it is very easy to use.

How can I visualize and analyze the measurement results of a CGQ experiment?

The measurement results are visualized by the CGQuant software itself and can be exported into MS Excel for further processing.

What does an exemplary result for a CGQ measurement look like?

Please take a look at the applications sections of our homepage or at the publications listed in this FAQ.

How to install the CGQ on your Shaker


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How to set up, start, pause and stop an experiment


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How to perform an OD calibration


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How to process & analyze CGQ data post experimentally


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How to take offline samples while using the CGQ


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Informational Material