A method and apparatus for selectively applying a print material onto a substrate for the synthesis of an array of oligonucleotides at selected regions of a substrate. The print material includes a barrier material, a monomer sequence, a nucleoside, a deprotection agent, a carrier material, among other...http://www.google.ca/patents/US6239273?utm_source=gb-gplus-sharePatent US6239273 - Printing molecular library arrays
