Abstract: Methods and devices are provided for manipulating droplets on a support using surface tension properties, moving the droplets along a predetermined path and merging two droplets together enabling a number of chemical reactions. Disclosed are methods for controlling the droplets volumes. Disclosed are methods and devices for synthesizing at least one oligonucleotide having a predefined sequence. Disclosed are methods and devices for synthesizing and/or assembling at least one polynucleotide product having a predefined sequence from a plurality of different oligonucleotides having a predefined sequence.

Abstract: Methods and apparatus relate to reduction of sequence errors generated during synthesis of nucleic acids on a microarray chip. The error reduction can include synthesis of complementary stands (to template strands), using a short universal primer complementary to the template strands and polymerase. Heteroduplex can be formed be melting and re-annealing complementary stands and template strands. The heteroduplexes containing a mismatch can be recognized and cleaved by a mismatch endonuclease. The mismatch-containing cleaved heteroduplexes can be removed from the microarray chip using a global buffer exchange. The error free synthetic nucleic acids generated therefrom can be used for a variety of applications, including synthesis of biofuels and value-added pharmaceutical products.