DNA synthesis devices, systems, and methods are disclosed. An apparatus can include a synthesizer chip having an array of reaction units in a predetermined pattern, each reaction unit including a reaction surface and a reaction electrode of an IC array of reaction electrodes, and a synthesizer chip controller coupled to the IC array of reaction electrodes configured to address each reaction electrode individually. The apparatus can also include a reagent delivery chip positionable above the synthesizer chip, comprising an array of reagent delivery units arranged in the predetermined pattern, each reagent delivery unit including a reagent electrode of an IC array of reagent electrodes and each reagent delivery unit configured to receive and deliver a droplet of reagent fluid having a volume of 1 picoliter or less, and a reagent delivery chip controller coupled to the IC array of reagent electrodes configured to address each reagent electrode individually.