Comment by abecedarius

Added: https://en.wikipedia.org/wiki/Nanopore_sequencing offers compact sequencers. Here's a handheld one: http://www.wired.com/2012/03/oxford-nanopore-sequencing-usb/ There can't be any physical barrier to high-quality readout by machines as small as a cell, because our own cells do it. I only brought that up because, ironically, I know more about cells than nanopore sequencing.