Development of an Optical Biosensor Based on the Goos-Hänchen Shift and Surface Plasmon Resonance for Rapid Detection of Cancer Cells

Early detection of cancer cells is crucial for effective disease management and personalized treatment. This study presents an advanced optical biosensor that integrates the Goos-Hänchen (GH) shift with Surface Plasmon Resonance (SPR) for highly sensitive, label-free and rapid cancer cell detection. The system consists of a red diode laser, beam splitter, polarizer, high-refractive index rotatable prism, and quadrant detector (QD) for precise lateral beam shift measurements. A differential configuration with control and test targets minimizes noise and enhances measurement accuracy. Lung (A549) and colon (LS180) cancer cells were cultured on nanoscale gold-coated glass substrates, interacting with the evanescent wave under total internal reflection (TIR). SPR analysis revealed resonance dip shifts of ~ 1.6° for LS180 and ~ 2.2° for A549 cells, while GH shift measurements further improved diagnostic precision, yielding lateral displacements of ~ 5.8 µm for LS180 and ~ 6.5 µm for A549. The sensor has a detection limit of ~ 500,000 cells/cm² and a refractive index sensitivity of 160°/RIU for LS180 and 220°/RIU for A549. With a limit of detection (LOD) of ~ 6.8 × 10⁻⁴ RIU and a figure of merit (FOM) of 106.7 (LS180) and 146.7 (A549), the system demonstrated high resolution and sensitivity. The dynamic range spans refractive indices from ~ 1.33 to 1.37, enabling broad analyte detection. A signal-to-noise ratio (SNR) of 20:1 confirms robust signal reliability. By integrating the GH shift with SPR, this dual-mode biosensor significantly enhances sensitivity and accuracy, enabling rapid, non-invasive cancer cell detection. Its ability to distinguish between lung and colon cancer cells marks a valuable advancement in clinical diagnostics, supporting early detection and personalized medicine.