a. High-density oligonucleotide arrays are produced at NASA Ames Research Center using the Maskless Array Synthesizer (MAS) system, which is a bench top, fully integrated, high-density in situ  DNA array fabrication instrument.

The MAS technology permits unsurpassed speed --a total synthesis time of less than two hours-- in the production of high-density custom 24-mer oligonucleotide arrays, thereby substantially reducing development time and costs, and making customization possible.

The MAS technology enables the design and fabrication of customized oligonucleotide arrays with densities (more than 786,000 different oligonucleotide features in a 2.3 cm² area) superior to all-of-the high-density mass production arrays. These arrays can be designed in minutes, and manufactured in less than two hours, resulting in the ability to perform truly iterative experiments in a single day. This iterative approach also allows for the continual optimization of the array design, as data is accumulated and processed.

b. Medium-density oligonucleotide arrays are produced at NASA Ames Research Center using electrochemistry in a bench top, fully integrated array of circuits that contain arrays of microelectrodes that are individually addressable using logic circuitry on the chip.

Electrochemical reaction in a porous reaction layer permits synthesis of oligonucleotides within a three-dimensional layer above the semiconductor surface. This in situ  synthesizer enables the design and fabrication of customized oligonucleotide arrays with densities up to 10,000 different oligonucleotide features in a 2 cm² area, with high nucleotide content per each feature.