This invention provides a sensor device, which comprises a conductive substrate, a composite layer, and a modified layer. The composite layer disposed on the conductive substrate, and includes a plurality of carbon nanotubes randomly crossing one another, and a plurality of gold nanoparticles attached to the carbon nanotubes. The modified layer, disposed on the composite layer, includes a plurality of reduced graphene oxide which partly covered on the carbon nanotubes. In addition, this invention also provides a method of fabricating the sensor device. |