Black Phosphorus-Based Slotted D-Shaped PCF SPR Sensor for Cancer Detection

This work proposes a slotted D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor for the detection of cancerous cells. Cancerous analytes are used in different concentrations having different refractive indices (RI) in the sensing medium. To confine the light in PCF, two types of air holes are incorporated, i.e., circular and oblong-shaped air holes. The designed PCF is coated with a gold layer (50 nm) along with TiO₂ (12 nm) that works as a plasmonic enhancer as well as an adhesive to stick the PCF with gold. Apart from gold + TiO₂, an additional seven layers of emerging plasmonic material—black phosphorus are coated on the frame to enhance the sensitivity having a monolayer thickness (0.53 nm). Since healthy and infected cells have different RI, therefore the coupling conditions also differ, which is reflected in peak confinement loss wavelength shift. With the help of the spectral shift, respective wavelength sensitivity (WS) is determined. The WS obtained for cervical, blood, skin, adrenal gland, and breast (types 1 and 2) cancerous cells are 5417 nm/RIU, 6071 nm/RIU, 4750 nm/RIU, 9286 nm/RIU, 11,429 nm/RIU, and 10,714.29 nm/RIU, respectively. The recorded results show that our proposed sensor is a better counterpart among previously proposed sensors and suitable for cancer cell detection.