Graphene and gold nanoparticles integrated terahertz metasurface for improved sensor sensitivity

Terahertz metamaterial technology, as an efficient nondestructive testing method, has shown great development potential in the detection of biological samples. In this study, we have proposed a graphene-integrated gold nanoparticles (AuNPs) terahertz (THz) biosensor and have analyzed the sensing performance of four IC-type resonators (ICSRs) for biosensors: bare ICSRs, ICSRs-integrated AuNPs, ICSRs-integrated graphene, and ICSRs-integrated graphene and AuNPs. The AuNPs generate charge accumulation and induce local electric field enhancement due to the tip effect, and enhance the interaction between the THz wave and the analyte, thus improving the sensitivity of the sensor. The combination of AuNPs and ICSRs-integrated graphene results in sensors with more pronounced amplitude changes and higher sensitivity. Due to the Fermi energy level of graphene being close to the Dirac point, the sensor is ultra-sensitive to external stimuli with a limit of detection of 10.48 fg/ml for aspartic acid solutions. This biosensor has the potential to detect trace amino acids with high sensitivity, contributing to early disease detection and environmental detection for early diagnosis and ecological balance.