A Reconfigurable SPR-Based D-Shaped Dual-Sensing Photonic Crystal Fiber Biosensor Using Ge₂Sb₂Te₅ Phase Change...

A surface plasmon resonance (SPR)-based D-shaped photonic crystal fiber biosensor has been proposed as an effective technique for detecting cancer. Despite several advanced SPR biosensor designs that have been reported to achieve high sensitivity, most exhibit non-uniform responses toward different cancerous cells and lack reconfigurability. Since sensitivity strongly depends on the plasmonic material, distinct sensors are often preferred for specific cancerous cells. However, previous studies on common cancer types have not explicitly addressed the issue of non-uniform sensitivity across different cells, as the widely varying sensitivity has not been systematically analyzed or treated as a key design concern, thereby limiting the general applicability of existing SPR biosensors. In this work, we define and address this gap for the first time by proposing a reconfigurable SPR-based D-shaped PCF biosensor utilizing an Au/Ge₂Sb₂Te₅ (GST) phase change material (PCM) interface. The distinct crystalline and amorphous phases of GST, exhibiting significant optical contrast, provide dual sensing capability and thereby enable different sensitivity responses for the detection of various cancer cells. In the amorphous GST, high sensitivity is observed for skin (4000nm/RIU), cervical (3333.33nm/RIU), and breast II (MCF-7) cancer (2857.14nm/RIU). In contrast, the crystalline phase exhibits high sensitivity in blood (2857.14nm/RIU), adrenal (2857.14nm/RIU), and breast I (MDA-MB-231) cancer (2857.14nm/RIU). Thus, by switching the GST phase, the sensor can be reconfigured to select different cancerous cells. Hence, the reconfigurability of the PCM effectively mitigates the issue of non-uniform sensitivity of conventional SPR-based biosensors, demonstrating the strong potential and versatility for futuristic biosensing technologies.