Patent ID: 8546772

Claim:
A method for detecting features of an array, comprising: (a) providing a flow cell comprising a first interior surface and a second interior surface that are in a generally mutually facing relation, wherein the first interior surface and the second interior surface are separated by a fluid passage, wherein an array of nucleic acid sites is present on the first interior surface and on the second interior surface, wherein the nucleic acid sites are present at a density of at least 1,000 sites per square millimeter; and (b) performing a sequencing by ligation reaction, comprising: (i) introducing fluorescent oligonucleotides to the flow cell to add fluorescent tags to the nucleic acid sites; (ii) detecting the fluorescent tags at the nucleic acid sites of the array on the first interior surface at a resolution to distinguish the nucleic acid sites on the first interior surface; and (iii) repeating steps (b)(i) and (b)(ii).