A photonic crystal nanocavity-based optical biosensor is proposed in this work, targeted to the detection of cancer cells and the measurement of urine/tear glucose concentration. The shift in cavity resonance, owing to the change in refractive index of the surrounding analyte, governs the sensing mechanism. Different design parameters of the biosensor are optimized for performance enhancement, leading to a quality factor of \(3.6496\times 10^5\) , sensitivity of 1158 nm/RIU, figure-of-merit of \(3.46\times \,10^5\,\text{RIU}^{-1}\) , and a detection limit of \(2.89052\times \,10^{-7}\) RIU. The resonance shift (1562–1620 nm) is found to be almost linear over a wide range of RI (1.335–1.41). Simulations under exposure to different types of cancerous/ healthy cells and tear/urine samples of different glucose concentrations show the biosensor’s potential to easily detect/measure its analyte using low-cost characterization tools. An investigation of its performance robustness against fabrication imperfections shows significant imperfection tolerance of up to 20 nm, indicating high device-yield and close conformity of the results with practical ones. These merits make the sensor ideal for label-free diagnostics of biomolecules and non-invasive measurement of glucose concentration using a small footprint device.
