Ion semiconductor sequencing

A microwell containing a template DNA strand to be sequenced is flooded with a single species of deoxyribonucleotide triphosphate (dNTP).

This causes the release of a hydrogen ion that triggers an ion-sensitive field-effect transistor (ISFET) sensor, which indicates that a reaction has occurred.

If homopolymer repeats are present in the template sequence, multiple dNTP molecules will be incorporated in a single cycle.

The technology was licensed from DNA Electronics Ltd,[1][2] developed by Ion Torrent Systems Inc. and was released in February 2010.

[4] Roche's 454 Life Sciences is partnering with DNA Electronics on the development of a long-read, high-density semiconductor sequencing platform using this technology.

[5] In nature, the incorporation of a deoxyribonucleoside triphosphate (dNTP) into a growing DNA strand involves the formation of a covalent bond and the release of pyrophosphate and a positively charged hydrogen ion.

The series of electrical pulses transmitted from the chip to a computer is translated into a DNA sequence, with no intermediate signal conversion required.

[11] The cost of acquiring a pH-mediated sequencer at time of launch was priced at around $50,000 USD, excluding sample preparation equipment and a server for data analysis.

[3][8] The throughput is currently lower than that of other high-throughput sequencing technologies, although the developers hope to change this by increasing the density of the chip.

[3][4] The company hopes that their system will take sequencing outside of specialized centers and into the reach of hospitals and smaller laboratories.