A highly sensitive gas-sensing platform based on a metal-oxide nanowire forest grown on a suspended carbon nanowire fabricated at a wafer level

•A ZnO nanowire forest was circumferentially grown on a suspended carbon nanowire.•Circumferentially distributed nanowire arrangement allowed efficient gas access.•Suspended sensor architecture enhanced gas sensing performances.•Entire nanowire-based sensor devices were fabricated using wafer-level processes.