Traumatic brain injuries (TBI) patients suffer from neurological deficits and increased risk of neurological disease, so there is a need for accurate, high throughput, and rapid diagnosis. Currently, TBI severity is detected and assessed using neurological examination and CT imaging, which require expensive hospital and doctors office visits. Protein biomarkers have emerged as an objective means to diagnose TBI; however, proteins are typically detected using time consuming and expensive methods such as ELISA and Western blot. In this work, a paper-based lateral flow assay (PLFA) has been developed for a rapid, low-cost means for detecting TBI biomarkers in blood plasma. PLFAs have received increasing attention due to their low cost and ease-of-use. However, these devices suffer from poor sensitivity and interference from the blood plasma matrix. In this study, surface-enhanced Raman scattering (SERS) was applied into a PLFA as the signal transducer to improve sensitivity and overcome biological interference. These advantages are attributed to the optical excitation in the near-infrared biological transparency window and SERS nanostructure design. The PLFA is designed using a plasmonic nanoarray chip and a blood plasma separation unit for highly sensitive TBI biomarker detection.