Biomass Measurement in Shake Flasks: A Comparison Between Optical Density and Backscatter Light

Is Optical Density The Best Choice For Your Application?

Considered an industry standard, most turn to the well-established method of optical density (OD) for biomass monitoring. However, while it is a well-known measurement type, several drawbacks make this not a “best fit” solution for many applications. Recent advances in technology, both in and outside the field of biotechnology, have led to new approaches. One such approach, backscatter, is a fast-growing trend that is helping researchers move past the “black box” of cell culture. But which one is right for your application? Learn about the pros and cons of both working principles and how they influence the measurement.


What is Optical Density (OD600)?

Optical density to measure biomass is a well-known, long time practiced offline technique, used, and described in many publications.

What is Backscatter Light?

A newer, more modern approach to biomass monitoring is backscatter. Like OD, backscatter uses a device that contains both a light source and a light detector. In contrast, however, both the source and sensor are located on the same side of the sample.


See It Action

The Cell Growth Quantifier (CGQ) is SBI’s solution to biomass monitoring in shake flasks and other vessels. This optical sensor-based technology uses backscattering light to monitor biomass and growth rates, producing high-resolution growth curves of each culture. Dr. Julia Hitschler from The University of Frankfurt has been using the Cell Growth Quantifier (CGQ) with her team for the last five years. They often use the device for screenings and for toxicity tests. Using the CGQ, they were able to see the effect of different m-cresol concentrations on the growth of S. cerevisiae CEN.PK2–1C “with high resolution and without any time-consuming manual sampling required for offline OD growth curves.”


Both OD and backscatter measurements can be used to successfully measure biomass in cell cultures. While many are most familiar with optical density, backscatter is the up-and-coming trend in biomass monitoring. Each method has pros and cons and knowing these points can make all the difference for your application.

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