Our research introduces a unique refractive index (RI) biosensor utilizing surface plasmon resonance (SPR) for the detection of cancerous cells. The sensor design incorporates two elliptical channels, two elliptical air holes, and four circular air holes, ensuring manufacturing simplicity. Gold (Au) is employed as the plasmonic layer, while Tantalum Pentoxide ( \(\textrm{Ta}_2\textrm{O}_5\) ) is selected as the oxide coating owing to its superior performance in enhancing analyte interaction. The proposed PCF-SPR structure benefits from two large elliptical air holes, reducing fabrication complexity and minimizing light leakage. Its performance is numerically investigated using the finite element method (FEM). Optimized structural parameters yield a maximum wavelength sensitivity (WS) of 10,000 nm/RIU and 19,000 nm/RIU for channels 1 and 2, respectively. The highest amplitude sensitivity (AS) reaches 374.35 \(\textrm{RIU}^{-1}\) and 888.52 \(\textrm{RIU}^{-1}\) , with peak figures of merit (FOM) of 135 \(\textrm{RIU}^{-1}\) in ch-1 and 179 \(\textrm{RIU}^{-1}\) in ch-2. When both channels are filled with the same analyte, the sensor demonstrates a remarkable WS of 18,000 nm/RIU, angular sensitivity of 1456.29 \(\textrm{RIU}^{-1}\) , and FOM of 274 \(\textrm{RIU}^{-1}\) , along with a broad RI detection range of 1.28−1.42. Furthermore, it efficiently detects malignant cells, achieving a maximum WS of 11,000 nm/RIU with a wavelength resolution of \(9.09 \times 10^{-6}\) RIU for cervical (HeLa) cells. The proposed biosensor, with dual-channel analyte sensing, broad RI range, and outstanding sensitivity, offers potential for simultaneous detection of biomolecules, glucose, carcinogenic substances, and other chemical compounds.
