A microplasma device includes a substrate and either or both of a microchannel or microcavity defined in a polymer layer supported by the substrate. Electrodes arranged with respect to the polymer material can excite a plasma in a discharge medium contained in the microchannel or the microcavity or both. A method of forming a microplasma device places a curable polymer material between a mold having a negative volume impression of microcavities and/or microchannels and a substrate. The polymer is cured and then the mold is separated from the solid polymer.