Construction
of oligonucleotide arrays
•The light flash is produced by photolithography using a mask to allow light to
strike only the required features on the surface of the chip.
•Oligonucleotide are synthesized in situ in the silicon chip.
In each step, a flash of light “deprotects” the oligonucleotides at the
desired location on the chip; then “protected” nucleotides of one of the four
types (A, C, G or T) are added so that a single nucleotide can add to the
desired chains. There are four types of masks according to the added nucleotide.