Helicos True Single Molecule Sequencing (tSMS) technology really lies on the borderline of second and third generation technologies.
While it still requires a "wash-and-scan" cycle and optical detection methods, it doesn't require amplification, meaning that each DNA fragment is only sequenced once. In fact, it uses a method very similar to Illumina's reversible termination, except for the difference noted. Like reverse termination, each DNA fragment is repeatedly exposed to a cycle of four different labeled nucleotides for a read length of up to 55 bases. However, it costs a significant amount. (38) (44)
The image above was taken by the HeliScope which uses tSMS technology, and shows billions of individual DNA fragments being sequenced. Each bright dot is a DNA fragment.
