The Virtuous Circle: Chemistry and Electronics
Blogger David Brock is a Senior Research Fellow at CHF's Center for Contemporary History and Policy.
One of the largest instrumentation firms on the planet, Life Technologies, made a splash recently with its announcement of the first commercial DNA sequencer to employ semiconductor sequencing. Much of the excitement around the Life Technologies announcement, and semiconductor sequencing in general, is the tremendous speed of the approach, and the relatively low cost of the instrument itself. The Ion Personal Genome Machine is faster than the current second generation—and the emerging third generation—DNA sequencers, completing a run in just two hours. At $50,000, the cost of the instrument is also an order of magnitude cheaper than these other systems.
The provocatively named Ion Personal Genome Machine relies on proprietary silicon microchips. These chips are made using conventional semiconductor technology, and contain large arrays of pH sensors underneath a matching array of micro-wells. The chips detect changes in pH to provide sequence data. Semiconductor sequencing, then, is DNA sequencing in an entirely new technological mode: electrochemical detection, rather than optical observation.
However, there are important limitations of the current semiconductor sequencer as compared to its newer optical rivals: it produces a significantly lower amount of sequence data per run, can only sequence relatively short segments of DNA, and, because a new chip must be used for each run, the cost per sequenced base pair is actually higher. Nevertheless, Life Technologies and others hope that semiconductor sequencing will lead to Moore’s Law-like increases in functionality and decreases in cost. Commercialization of semiconductor sequencing could lead to a segmentation of the sequencing market, with low-system-cost machines like that from Life Technologies used primarily for diagnostic work.
Jonathan Rothberg, who developed the Ion Personal Genome Machine, is fond of describing semiconductor sequencing as “Watson meets Moore,” that is James Watson of double helix fame, and Gordon Moore of Moore’s Law fame. Rothberg’s phrase points out that semiconductor sequencing is the latest in a long series of virtuous circles of innovation produced by the intersection of chemistry with electronics.
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