# Chemistry and Imaging on the NovaSeq X Series Instruments

The NovaSeq X Series is powered by XLEAP-SBS chemistry, a faster, higher quality, and more robust update to proven Illumina sequencing by synthesis (SBS) chemistry.

**Chemistry**

The NovaSeq X Series uses two-color chemistry, which allows for very fast imaging of the flow cell using blue and green channels at every sequencing cycle.

* Clusters with intensity in **green** only: **T**
* Clusters with intensity in **blue** only: **A**
* Clusters with intensity in both channels: **C**
* Clusters with no intensity/dark: **G**

  ![](https://761066130-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FGM9W2DuBTgEXv1ClCm8H%2Fuploads%2Fgit-blob-d4e9a85acc586ee23da2182521b9077cf2917de4%2Fimage1.jpg?alt=media\&token=6fd57f81-e89c-478a-8e43-97dc3ad666c3)

Please note the following differences between the NovaSeq X Series and other two-channel Illumina platforms:

* The NovaSeq 6000, NextSeq 500/550, and MiniSeq: A channel uses combined Red and Green, and the C channel uses Red only.
* The NextSeq 1000/2000 (Standard Reagents): A channel uses combined Blue and Green, and the C channel uses Blue only.
* The NextSeq 1000/2000 (XLEAP Reagents): C channel uses combined Blue and Green, and the A channel uses Blue only.

**1.5B Flow Cell Layout**

There are 2 swaths per surface (2 top and 2 bottom), 2 surfaces per lane, and 70 tiles per swath for a total of 560 tiles imaged.

![](https://761066130-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FGM9W2DuBTgEXv1ClCm8H%2Fuploads%2Fgit-blob-3e4f4f9a71e99db85c60a9514f7f40c5a4d84824%2Fimage2.png?alt=media)

**10B Flow Cell Layout**\
There are2 swaths per each surface (2 top and 2 bottom), 2 surfaces per lane, and 98 tiles per swath for a total of 3136 tiles imaged.

![](https://761066130-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FGM9W2DuBTgEXv1ClCm8H%2Fuploads%2Fgit-blob-2d7a332aa2425c0df0655ecf8e69e1c2132be9e1%2Fimage3.jpg?alt=media)

**25B Flow Cell Layout**

There are 4 swaths per each surface (4 top and 4 bottom), 2 surfaces per lane, and 98 tiles per swath for a total of 6272 tiles imaged.

![](https://761066130-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FGM9W2DuBTgEXv1ClCm8H%2Fuploads%2Fgit-blob-836cc1fe7c790ced6146b7a53dc5a9e5497ca0ee%2Fimage4.png?alt=media)

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