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This paper presents the design and characterization of a novel metamaterial with five distinct operating bands for THz applications. The proposed metamaterial is constructed using an ultra‐thin polyimide substrate. The proposed metamaterial has a square geometry with metallic patterns suitably designed to obtain the desired frequency characteristics. The metamaterial operates based on surface plasmon hybridization with stopband characteristics at 0.82, 1.96, 2.77, 3.40 and 4.74 THz. The metamaterial has a small geometry 0.082λo × 0.082λo where λo is wavelength calculated under free‐space conditions at 0.82 THz. The operation of the proposed pentaband metamaterial is described using electric field distributions. The metamaterial reported in this paper has rotational symmetry and hence it is polarization independent. The performance of the metamaterial for various angles of incidence has been evaluated and the results reveal that the proposed metamaterial is stable up to ±70 degrees. The THz metamaterial is appropriate for components like frequency selective surface, sensors and detectors. [ABSTRACT FROM AUTHOR]

[Display omitted] • A terahertz metamaterial sensor with "X" double-peak structure is designed. • The transmission peak shifts to high frequency with the increase of concentration. • A new strategy is proposed to solve the problem of excessive concentration span. • The LOD of the sub-model of low and medium concentration has been improved. Food such as cereal crops, oil crops and dairy products are very easy to produce highly toxic and carcinogenic aflatoxins during inappropriate storage. Therefore, it is of great significance to achieve rapid, non-destructive and highly sensitive detection of aflatoxin. A terahertz metamaterial sensor with "X" compound double-peak structure is designed based on electromagnetic theory to realize highly sensitive detection of aflatoxin B2 solution. It is found that the amplitude of the transmission peak of the terahertz transmission spectrum of aflatoxin B2 (AFB2) solution around 1.2 THz and 2.0 THz gradually decreased with the increase of the concentration of aflatoxin B2 solution, and the frequency of the transmission peak gradually shifted to high frequency with the increase of the concentration of aflatoxin B2 solution, hence a full concentration model was established. And a strategy of first classifying concentration intervals and then building a grouped quantitative model was proposed. The Limit of Detection (LOD) of the interval sub-model of low and medium concentration of aflatoxin B2 solution has been greatly improved with the LOD of the optimal grouping model was 7.28 × 10−11 mg/ml, 4.19 × 10−9 mg/ml and 1.22 × 10−7 mg/ml, respectively. This research verifies the feasibility of terahertz metamaterial sensor based on "X" composite double-peak structure combined with THz-TDS technology for highly sensitive detection of aflatoxin B2 solution. And it provides a new rapid, non-destructive and highly sensitive detection of aflatoxin in food. [ABSTRACT FROM AUTHOR]