VO2-operated stub and rectangular cavity-based plasmonic refractive index sensor for biomolecules detection

This paper introduces a theoretical study of plasmonic metal insulator metal (MIM) sensor based on a rectangular resonator with a stub structure. The integration of VO₂ in the stub in a MIM waveguide configuration introduces a novel approach for tunable sensing for biomolecules and refractive index sensing applications. The sensing property of the device is analyzed for both the insulator and metallic states of the VO₂ showing enhanced resonance peaks for refractive index sensing. The device achieves a sensitivity of 666nm/RIU for its two resonance modes with quality factor (Q) of 47.56 and figure of merit (FOM) of 18 for water, acetone and dimethyl sulfoxide. Further, the device shows its strong biosensing potential by detecting numerous brain cancer cell components and differentiating between DNA samples. For brain cancer detection, maximum sensitivity of 950.11 nm/RIU and 826.11nm/RIU is achieved for the metallic and insulator state of VO₂ respectively. In the insulator state, a Q factor of 91 and FOM of 33.2 is achieved for Medulloblastoma, whereas for the metallic state of VO₂, an FOM of 47.5 and a Q factor of 57 is obtained. Additionally, the device can also differentiate between different DNA samples and can achieve Q of 62 and FOM of 22. Device optimizations are performed by changing device parameters and their significant effect on device's performance has been observed. The highest quality factor of 86 is calculated by changing the internal dimensions of the rectangular cavity. With the ability to detect numerous refractive indexes in the range from 1.33 to 1.56, the proposed device offers significant applications for biosensing and refractive index based applications.