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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.

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 75 °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?

In order to avoid the interference of external light sources and to allow for accurate biomass monitoring at low cell densities, the flasks need to be covered. You can, however, always pause an experiment and remove the cover while the CGQ is not measuring.

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, Streptomyces venezuelae, Gluconobacter oxydans, Klebsiella pneumoniae, Vibrio cholerae, Chromobacterium violaceum, Clostridium ljungdahlii, Clostridium acetobutylicum, Blautia producta, Hungatella hathewayi Saccharomyces cerevisiae, Schizosaccharomyces pombe, Pichia pastoris, Yarrowia lipolytica,  Kluyveromyces lactis, Hansenula polymorpha
Archaea Other
Sulfolobus acidocaldarius, Haloferax volcanii Aspergillus niger, Ustilago maydis, Chlorella vulgaris (Microalgae), Nicotiana tabacum (Plant Cells)

Can I use the CGQ with photosynthetic organisms?

Due to the covers that need to be used during measurements, the CGQ cannot be used with photosynthetic organisms (yet).

Which media have been successfully used with the CGQ?

Some of the media the CGQ has been used with are: LB, TB, YPD, Brock, various Mineral and Minimal media (e.g. M9)

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 bacteria
  • Non-invasive monitoring of thermophilic organisms
  • Toxicity tests
  • Reproducible production of competent cells
  • Up-scaling
  • Quality control

OD Measurements

Can I measure OD by using the CGQ?

The CGQ backscatter signal and OD600 show a strictly monotonic non-linear correlation. For measuring OD in real time, the user can create a calibration curve with the CGQuant software by providing specific OD values to the CGQ.

Can I use one OD 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 OD.

What is the OD measurement range?

Usually, the OD600 measurement range lies between 0.2 and >50.


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

Windows 7 or newer; Dual Core @ 2 GHz/core; RAM => 4GB, HDD => 1GB

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.

What does the user interface look like?

You can directly interact with the interface by installing the trial version (that you can find here) or see some of the basic tools being used at the video tutorials.

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

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

How to perform an OD calibration

How to process & analyze CGQ data post experimentally

How to take offline samples while using the CGQ

Informational Material


CGQ Information Material 7.53 MB

Download our latest CGQ Information Material. This PDF contains information on: What...

    User Guide


    CGQ User Guide 3.14 MB

    Our handbook for cell density monitoring in shake flask and bioreactor aplications ...