<p>In this study, we developed a sensor design for the detection of cancer cells, employing a tri-layer reflective structure with tailsored refractive index properties. The proposed design utilizes a periodic arrangement of Si, Si₃N₄, and SiO₂ layers to achieve a unique photonic band gap effect by exciting Tamm plasmons at the interface of a metal and the tri-layer reflective structure. The proposed structure&#xa0;was analyzed by using the FDTD method implemented in Ansys Lumerical FDTD software. In the present paper, we have numerically calculated the effect of metal layer thickness and analyte layer thickness on the reflection spectrum. The sensor’s performance was optimized by changing the thickness of the metal and analyte layers; by choosing optimized parameters, the structure achieves high sensitivity, figure of merit, and quality factor values. The structure results in a reflection spectrum dip at 953&#xa0;nm with full width at half maximum of 5.37&#xa0;nm which represents the existence of a Tamm plasmon. Simulations in the near-infrared region show the sensor’s capacity to distinguish between normal and cancer-affected cells. The proposed waveguide design demonstrates a measurable shift in the Tamm plasmon resonance dip when interacting with different types of blood cells. For normal blood (Jurkat) cells, the reflection spectrum exhibits a Tamm plasmon dip at a wavelength of 974.3&#xa0;nm. In contrast, for cancerous Jurkat cells, the dip is observed at 981.6&#xa0;nm. This corresponds to a spectral shift of 7.3&#xa0;nm, indicating the potential of the design for distinguishing between healthy and affected blood cells based on their optical response. Apart from this, we have also evaluated the effect of various normal and cancer cells in tissues such as the skin (Basal), cervical (Hela), adrenal gland (PC12), and breast (MDA-MB-231 and MCF-7). This method could improve the precision and efficiency of biosensing while also providing substantial promise for future applications.</p>