Design and theoretical analysis of a metamaterial-assisted one-dimensional photonic crystal biosensor for prostate-specific antigen (PSA) detection

This study presents the theoretical design and analysis of a metamaterial-based one dimensional (1D) photonic crystal (PC) refractive index biosensor for detection of PSA. The proposed sensor design is distinguishable from typical 1D PC biosensors in that it comprises an arrangement of metamaterial end-cap layers symmetrically placed on both sides of a defect cavity within a periodic Si/SiO₂ multilayer structure. The metamaterial end-caps significantly improve the sensitivity of the resonance shift readout. The change in PSA concentration is modeled as a slight change in the refractive index of the defect cavity, leading to the observable shift of the photonic band-gap defect mode resonance wavelength. The optical transmission of the structure is computed using the impedance method. The optimal configuration for the biosensor achieves a sensitivity of 3628.9343 nm/RIU, a quality factor of 248.1131, and a figure of merit of 72.4625 RIU⁻¹. The findings indicate that the incorporation of metamaterial layers can significantly enhance the sensing capability of defect mode photonic crystal biosensors. The configuration proposed in this work holds excellent promise for the optical detection of biomolecular targets with high precision and provides an effective platform for further developments in refractive index-based biosensors.