We describe a platform for photoelectrophoretic transport and electronic hybridization of fluorescence-labeled DNA oligonucleotides in a low conductivity electrolyte. At the core of the platform is a chemically stabilized semiconductor photodiode or photoconductor surface coated with a streptavidin-agarose permeation layer. Micro-illumination of this surface generates photoelectrochemical currents that are used to electrophoretically transport and attach biotinylated DNA capture strands to arbitrarily selected locations. The same process is then used to transport and electronically hybridize fluorescence-labeled DNA target strands to the previously attached capture strands. Signal detection is accomplished either by a fluorescence scanner ora CCD camera. This represents a flexible electronic DNA assay platform that does not rely on pre-patterned microelectronic arrays.