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. The method can form a microplasma device that 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 plasma in a discharge medium contained in the microchannel or the microcavity or both. A flexible mold is preferably used to fabricate transparent polymer microcavities onto rigid substrates. A rigid mold is preferably used to fabricate transparent polymer microcavities onto flexible substrates. Having one of the mold and the substrate flexible and the other rigid aids in the separation of the mold from the cured polymer.