No abstract

No abstract

Organophosphate insecticides with broad spectrum and high efficiency make a great difference to agricultural production. The correct utilization and residue of pesticides have always been important issues of concern, and residual pesticides can accumulate and pass through the environment and food cycle, resulting in safety and health hazards to humans and animals. In particular, current detection methods are often characterized by complex operations or low sensitivity. Fortunately, using monolayer graphene as the sensing interface, the designed graphene-based metamaterial biosensor working in the 0–1 THz frequency range can achieve highly sensitive detection characterized by spectral amplitude changes. Meanwhile, the proposed biosensor has the advantages of easy operation, low cost, and quick detection. Taking phosalone as an example, its molecules can move the Fermi level of graphene with π–π stacking, and the lowest concentration of detection in this experiment is 0.01 μg/mL. This metamaterial biosensor has great potential in detecting trace pesticides, and its application in food hygiene and medicine can provide better detection services.

In recent years, the concept of bound states in the continuum (BICs) in optics has become a research hotspot and has attracted the attention of many scholars. It provides an important physical mechanism for the generation of high-quality-factor optical resonance in high-refractive-index dielectric nanoparticles and all-dielectric metasurfaces. In this paper, two metasurfaces with the same structure of different materials are proposed. The resonant frequencies of the two structures are consistent, and the error is within 2.5 GHz. The quasi-BIC resonance is excited in the same way of breaking the symmetry. Subsequently, the electric field distribution, sensitivity, and figure of merit (FOM) of the two metasurfaces are analyzed, and sensitivities of 79.3 GHz/RIU and 72.4 GHz/RIU and the highest FOMs of 424.8 and 180.5, respectively, are achieved. These two all-dielectric metasurfaces are compared in this study, further confirming the advantages of all-silicon metasurfaces.

A graphene-based metamaterial sensor working in the terahertz spectrum is proposed, simulated, and experimentally verified by measuring bovine serum albumin (BSA). Flexible, low-cost polyimide (PI) is used as the substrate, and aluminum with periodic square rings is chosen as the metal layer. Furthermore, the introduction of the graphene monolayer interacts with the molecules through π − π stacking, resulting in the highly sensitive detection of BSA by calculating the amplitude changes at the resonance frequency. The sensor, which is a biosensor platform that offers the advantages of a small size, high sensitivity, and easy fabrication, is a promising method for THz biological detection.