An ambient environment nanowire sensor and corresponding fabrication method have been provided. The method includes: forming a substrate such as Silicon (Si) or glass; growing nanowires; depositing an insulator layer overlying the nanowires; etching to expose tips of the nanowires; forming a patterned metal electrode, with edges, overlying the tips of the nanowires; and, etching to expose the nanowires underlying the electrode edges. The nanowires can be a material such as IrO.sub.2, TiO.sub.2, InO, ZnO, SnO.sub.2, Sb.sub.2O.sub.3, or In.sub.2O.sub.3, to mane just a few examples. The insulator layer can be a spin-on glass (SOG) or low-k dielectric. In one aspect, the resultant structure includes exposed nanowires grown from the doped substrate regions and an insulator core with embedded nanowires. In a different aspect, the method forms a growth promotion layer overlying the substrate. The resultant structure includes exposed nanowires grown from the selectively formed growth promotion layer.