In a preferred method of formation embodiment, a metal foil or film is obtained or formed with micro-holes. The foil is anodized to form metal oxide. One or more self-patterned metal electrodes are automatically formed and buried in the metal oxide created by the anodization process. The electrodes form in a closed circumference around each microcavity in a plane(s) transverse to the microcavity axis, and can be electrically isolated or connected. Preferred embodiments provide inexpensive microplasma device electrode structures and a fabrication method for realizing microplasma arrays that are lightweight and scalable to large areas. Electrodes buried in metal oxide and complex patterns of electrodes can also be formed without reference to microplasma devices—that is, for general electrical circuitry.