In this study, a high-precision optical biosensor composed of a structurally chiral medium (SCM) with ̄42m point group symmetry and an aluminum metallic layer has been theoretically investigated using the Kretschmann configuration for cancer cell detection. For numerical analysis, the 4 4 ́ transfer matrix method was employed to derive the absorption spectrum of the structure when subjected to p-polarized incident waves. The results indicate that two modes, surface plasmon polaritons (SPPs) and waveguide modes, can be excited at the metal-SCM interface. Our findings suggest that due to the minimal penetration of SPPs as an evanescent wave into the biosample region, waveguide modes are more advantageous for sensor applications. Furthermore, the resonance angle of the waveguide modes exhibits high sensitivity to the biosample’s refractive index, enhancing the biosensor’s functionality. Additionally, How the SCM layer tilt angle has been investigated, denoted as c , affects the absorption peaks and the biosensor’s efficiency. Optimal performance was achieved 30c = , although optimal sensor parameters vary across different biosample types.
