Suspended thin membranes have drawn increased attention due to their exceptional thermal properties. The membranes presented here are made of alumina (Al(2)O(3)), which offers several advantages over the traditional silicon nitride membranes. Alumina films are atomic layer deposited (ALD), which enables conformal deposition profiles at low deposition temperatures. Fabrication of nanocorrugated alumina membranes is demonstrated for the first time by coating nanostructured surfaces, such as silicon nanograss and polystyrene nanobeads, with a thin layer of alumina (20-200 nm), subsequently released by sacrificial plasma etching. The low deposition temperature (80 degrees C) of alumina makes it possible to coat sensitive materials, which opens up new possibilities in the field of polymer micro- and nanofabrication. Smooth alumina membranes were implemented both in continuous and in patterned forms. The smooth membranes, both continuous and perforated, were used as thermally insulating platforms for metallic devices, such as microheaters. The mechanical strength of alumina enables large suspended microstructures to be made of metals that would not have the mechanical strength in themselves.