Black Phosphorous-Based Highly Sensitive Surface Plasmonic Sensor for Detection of Formalin

In the present work, a highly sensitive prism-based surface plasmon resonance (SPR) sensor for the detection of formalin using multilayer black phosphorous (BP) is proposed. Formalin, which is widely used as a preservative, can cause a variety of diseases, making its detection crucial. The transfer matrix method is utilized to compare and analyze the proposed structures of the SPR-based prism sensor in the Kretschmann configuration. The effect of prism materials (BAK3, BK7, SF10, SF11, and 2S2G), metals (gold, silver, copper, and aluminum), and 2-D materials (graphene, MoS2, WS2, and BP) on the performance of the sensor for formalin detection has been analyzed and discussed. The analysis of the impact of employing multilayer 2-D materials is carried out. Optimization of the thickness of the 2-D material is performed to achieve a structure that gives better sensitivity. The sensitivity achieved for structures with multilayer graphene, MoS2, and WS2 are 172.82°/RIU, 195.97°/RIU, and 218.04°/RIU, respectively. A highly sensitive structure for formalin detection is proposed with BK7, silver, and nine layers of BP. A sensitivity of 289.4565°/RIU and a detection accuracy (DA) of 0.3125/° are obtained. The limit of detection of the proposed sensor for different concentrations of formalin lies in the range of 3.45–
$3.56~ \mu $
RIU.