What do the intervals between groups of arrays in microarray gene expression data images mean?
The borders provide visual cues for the image analysis software to know which spot is which. The spots are also not printed all at once, but by a series of print heads, and the spaces allow for a small amount of error in the alignment of the print heads. It also allows for humans to more easily eyeball the results - the chip map can be printed in groups, and if you're looking to see what gene X did in your experiment, and know it's in the 2nd row, in the 2nd block, row 8, column 4, you can find it more easily than just knowing it's in row 73, column 27.