A microplasma device of the invention includes a microcavity or microchannel defined at least partially within a thick metal oxide layer consisting essentially of defect free oxide. Electrodes are arranged with respect to the microcavity or microchannel to stimulate plasma generation in said microcavity or microchannel upon application of suitable voltage and at least one of the electrodes is encapsulated within the thick metal oxide layer. Large arrays can be formed and are highly robust as lack of microcracks in the oxide avoid dielectric breakdown.