Even as third-generation techniques are still developing, more radical
"fourth-generation" techniques are already starting to be formulated.
You may have noticed that of all the methods which have been discussed so far, each generation builds on the developments of the previous one. Unlike third-generation techniques, fourth-generation techniques do not require observing DNA polymerase synthesizing DNA. Rather, they use a radically new approach completely different from all approaches we have discussed so far. Fourth-generation techniques involve direct observation of the DNA itself. The fourth-generation techniques exhibit perhaps the greatest diversity of different approaches. Technologies involving nanopores, or tiny holes through which DNA is threaded like a ring on a string and can be biological or synthetic, are completely different from past generations which require DNA polymerase. Other technologies that can be considered fourth generation includes atomic imaging techniques such as tunneling electron micrsocopy (TEM) by Halcyon Molecular. This involves labeling each base with atoms that are heavier than normal, and then imaging DNA at an atomic level. (34) (44)
