PATENT WATCH | Photolithography Advances
Affymetrix, the Santa Clara, Calif.-based manufacturer of GeneChip® microarrays, has developed a new device to create microarrays, according to a recently awarded patent.1 The new technique replaces physical photolithographic masks with computer-generated ones, and will, according to the application, "significantly improve the cost, quality, and efficiency of polymer array synthesis."
GeneChip arrays typically consist of hundreds of thousands of 25-base-long oligonucleotide probes. These probes are synthesized on-chip, in parallel, using a process that employs photoreactive nucleotide building blocks. When exposed to light, these precursors become "deprotected," meaning they are available for coupling to the next nucleotide in the chain. Affymetrix (www.affymetrix.com) employs photomasks--small wafers riddled with holes-- to selectively illuminate, and thereby deprotect, different regions of the array that are to react with the next added nucleotide. In this way, each probe can be synthesized with a unique sequence.