An iridium oxide (IrOx) nanowire neural sensor array and associated fabrication method are provided. The method provides a substrate with a conductive layer overlying the substrate, and a dielectric layer overlying the conductive layer. The substrate can be a material such as Si, SiO2, quartz, glass, or polyimide, and the conductive layer is a material such as ITO, SnO2, ZnO, TiO2, doped ITO, doped SnO2, doped ZnO, doped TiO2, TiN, TaN, Au, Pt, or Ir. The dielectric layer is selectively wet etched, forming contact holes with sloped walls in the dielectric layer and exposing regions of the conductive layer. IrOx nanowire neural interfaces are grown from the exposed regions of the conductive layer. The IrOx nanowire neural interfaces each have a cross-section in a range of 0.5 to 10 micrometers, and may be shaped as a circle, rectangle, or oval.