Applications of Microarrays on DNA Chips
In late 1980S, it was believed that microarrays carrying all the possible 65,536 (48) octamer oligonucleotides may be used as an alternative to Sanger’s dideoxy method of sequencing. This was described as the method of sequencing by hybridization (SBH). However, this objective has not been successfully achieved, since uniform hybridization signals are not available for a large number of oligonucleotides in parallel, due to sequence dependent variability in parallel, due to sequence dependent variability in heteroduplex formation.

This leads to false positives and false negatives, so that unambiguous assembly of de novo sequences are not always possible. Further complications arise due to repeated sequences. Consequently, the technical barriers of SBH are now obvious, and microarrys which were initially considered to be usally only for SBH, are now used for a variety of other purposes, which include the following.