Toward nanoscale DNA writers: Unlocking scalable DNA data writing technology (microsoft.com)

I think this is the paper. You can also download a properly formatted PDF from there if you prefer that over a website with animated graphics:

https://www.science.org/doi/10.1126/sciadv.abi6714

The DNA storage project page is here:

https://www.microsoft.com/en-us/research/project/dna-storage...