Numerical Investigation of a Gear-Shaped Triple-Band Perfect Terahertz Metamaterial Absorber as Biochemical Sensor

In this work, a triple-band perfect metamaterial absorber (MA) in the terahertz (THz) regime is demonstrated for different biochemical sensing applications. The metasurface’s unit cell is made up of a distinct metallic gear-shaped core with eight identical teeth and two concentric circular rings (CCRs) on the top layer. Finite-difference time-domain (FDTD) method-based software is utilized for modeling and numerical analysis, and a genetic algorithm (GA) is employed to optimize some geometric parameters of the absorber. The proposed MA shows almost 100% absorption in the frequency range from 0.5 to 4.5 THz. The MA becomes almost insensitive to polarization angle when the number of gear tooth has been increased. Resonance frequencies can be tweaked by adjusting the top layer’s geometric parameters while maintaining the absorption constant. The influence of different metals and forms in the top layer, such as solid and hollow circular metallic cores, on absorption spectra is also illustrated in this article. The modeled MA can detect glucose, ethanol, oils, and cancer cells (BCCs) by changing the resonance frequency and peak absorption of the spectra due to the variation in refractive index (RI) of the sample. When detecting ethanol, the absorber achieves a maximum sensitivity and figure of merit (FOM) of 56.67 THz/RIU and 358.7 RIU
⁻¹
, respectively. In addition, the effects of incident angle of light and bending of MA on absorption are analyzed in this study. With this unique feasible design, structural tunability, and high sensitivity, the proposed absorber exhibits good promise in detecting biochemicals in the THz region.