• Highly porous nanostructured metal oxide network is created by oxygen plasma and heat treatment. • A generalized aqueous metal precursor solution is developed and enables the selection of large variety of metal salts. • As an example, a Co3O4-based sensor is established, showing high sensitivity selectivity, and fast response toward formaldehyde. • This facile and versatile fabrication strategy has great potential for low cost mass production. A facile and versatile approach that integrates highly porous metal oxide nanostructured network with a low power microheater platform is presented for the creation of low-power, miniaturized gas sensors. Highly porous nanostructured metal oxide network is formed by oxygen plasma treatment of a metal containing polymer film followed by a heat treatment. A generalized aqueous metal precursor solution allows a large variety of metal salts to be incorporated into cast polymer films, thus forming nanostructured metal oxide network with various compositions. Gas sensing behavior is demonstrated for Co 3 O 4 -based devices, exhibiting high sensitivity, low detection limit, and fast response and recovery towards formaldehyde gas. The overall fabrication process is flexible and highly scalable. This facile and flexible fabrication method can be used to reproducibly fabricate a variety of low power gas sensors with tunable performances for many applications and has great potential for mass production. [ABSTRACT FROM AUTHOR]