A signal-amplification device for surface enhanced Raman spectroscopy (SERS). The signal-amplification device includes a non-SERS-active (NSA) substrate, a plurality of multi-tiered non-SERS-active nanowire (MNSANW) structures and a plurality of metallic SERS-active nanoparticles. In addition, a MNSANW structure of the plurality of MNSANW structures includes a main arm of a plurality of main arms and a plurality of arms of at least secondary order. The plurality of main arms is disposed on the NSA substrate; and, a secondary arm of the plurality of arms is disposed on the main arm. Moreover, a metallic SERS-active nanoparticle of the plurality of metallic SERS-active nanoparticles is disposed on a surface of the MNSANW structure.