A handheld Surface-Enhanced Raman Spectroscopy (SERS) device for detecting a biomarker in a sample collected from a subject. The device comprises a laser generator configured to produce a laser beam; a nanoporous anodic aluminum oxide (NAAO) substrate configured to receive the sample collected from the subject; wherein the laser beam reaches the sample on the NAAO substrate and is reflected or deflected to produce a light signal; and a light sensor configured to receive the light signal reflected or deflected from the sample; wherein the device is handheld and detects the biomarker in the sample; wherein the NAAO substrate comprises a multilayered nanoporous aluminum layer; wherein the multilayered nanoporous aluminum layer comprises a base aluminum layer, and a nanoporous aluminum layer on top of the base aluminum layer; and wherein the nanoporous aluminum layer comprises a plurality of nanocavities.