> For the complete documentation index, see [llms.txt](https://help.sbtinstruments.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.sbtinstruments.com/measurement-essentials/dense-culture.md).

# Hit the right conductivity

BactoBox® uses detection in an electric field to discern cells from non-cellular objects. For this principle to work, conductivity needs to be controlled. In practice this is done by diluting samples into a diluent with well-defined conductivity.

## Most growth media must be diluted at least 1:100

As demonstrated in the video below, growth media have \~100 times higher conductivity than what is required for a BactoBox® measurement. Samples must therefore be diluted in diluent prior to measurements.

{% hint style="success" icon="square-bolt" %}

## Dilute at least 1:100 to hit the right conductivity

Most growth media must be diluted at least 1:100 to reach the conductivity range required for BactoBox® measurements (1,500–2,200 µS/cm).
{% endhint %}

<figure><img src="/files/toQenOOKIMjh0BihR2gU" alt=""><figcaption><p>Conductivity measurements for a dilution series of the growth medium. Dilutions of 1:100, 1:1,000, 1:10,000, and 1:100,000 all fall within the accepted conductivity range of 1,500–2,200 µS/cm. In contrast, the undiluted growth medium and the 1:10 dilution exceed the acceptable conductivity range.</p></figcaption></figure>

## Learn the ropes

This mini course provided you with the essentials on how to hit the right conductivity. Try our third tutorial for a hands-on example on how to get conductivity right when tracking a growth curve.

{% content-ref url="/pages/Kig8Uq7Hw23ovBr65Us0" %}
[Track growth curve](/tutorials/measure-vitroid-tm-growth-curve.md)
{% endcontent-ref %}

## Next steps

With these three mini courses on measurement essentials, you now have a foundation for testing your own cultures. In principle you can now proceed to our [Workflows](/mpd/workflows/bioprocess-workflows.md) in [Microbial process development](https://help.sbtinstruments.com/mpd/)

Before doing so, we still highly recommend that you complete tutorials 1-3. Alternatively, if you run into technical difficulties with your own cultures, use the tutorials as a fall-back option.

In any case, we are always happy to help. If you find yourself stuck, feel free to [Contact our support team](/troubleshooting/contact-our-support-team/contact-our-support-team.md) for assistance.


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