Highly Sensitive Biosensor Based on Metamaterial Absorber With an All-Metal Structure

In this article, an all-metal metamaterial absorber as a sensitive biosensor is proposed in the terahertz regime for biomolecular detection, such as protein, bacillus bacteria, and cancer cells. Here, the highly sensitive characteristic of the proposed absorber is implemented by the enhanced electromagnetic loss of symmetry-broken metal structures, where two discontinuous hollow rectangular metal arms are arranged orthogonally above the metal ground plane in geometry. Finite integral theory (FIT)-based software is utilized for modeling and full-wave numerical simulation. The results show that a near-perfect absorption of 100% at 1.99 THz is achieved with a quality factor value of 87, which could be an excellent performance in the terahertz regime below 2 THz. The electric and magnetic field distribution analysis is performed to reveal the mechanism, which is the significant confinement of electromagnetic field in the specially designed metal structure. The sensing performance of a refractive index is also investigated, and the resonance frequency and peak absorption of the spectra will get shift due to the variation of biological samples. The maximum sensitivity and figure of merit reach 540 GHz/RIU and 23.5 RIU−1, respectively. In addition, the effect of polarization angles and performance under different incident angles is also discussed. The presented biosensor with high sensitivity and feasible fabrication is a good candidate for biomedical detection in the terahertz regime.