LiNbO3 photonic crystal (PhC) based bio-sensor for cancerous cell detection in the visible band

A new photonic crystal (PhC)-based biosensor has been developed and analysed for detecting cancerous cells within the visible wavelength range of 650–740 nm. The proposed structure consists of a hexagonal lattice of air holes embedded in a lithium niobate (LiNbO 3 ) dielectric substrate. A key feature of the design is the incorporation of a hexagonal nanoring resonator, which forms a well-defined sensing region and enhances light–matter interaction, thereby improving sensing performance. The biosensor is evaluated for its ability to distinguish between normal and cancerous biological samples, including adrenal, skin, blood, cervical, and two types of breast cancer cells. The device performance is assessed in terms of quality factor, sensitivity, figure of merit, and detection limit. Simulation results demonstrate quality factor values of 484 for normal cells and 481 for cancer cells, along with a sensitivity of 135.71 nm/RIU, a figure of merit of 89.17 RIU⁻ 1 , and a detection limit of 1.12 × 10 -3 RIU. The observed shifts in resonance wavelength enable clear differentiation between healthy and malignant cells. Numerical modelling using the Optiwave Finite-Difference Time-Domain (OptiFDTD) method validates the optical performance of the proposed biosensor. The results confirm that the PhC nanoring resonator offers high sensitivity, strong selectivity, and reliable label-free detection. Owing to these characteristics, the proposed design shows strong potential for biomedical diagnostics, particularly for early-stage cancer detection that requires rapid, accurate, and non-invasive sensing.