A novel butterfly-shaped core mode-based asymmetric slotted sensor for ultra-high sensitivity in sucrose concentration detection

In this research, we proposed an asymmetric rectangular slotted biosensor using photonic crystal fiber (PCF), which is subject to surface plasmon resonance (SPR). The proposed sensor utilizes only seven air holes, ensuring better fabrication feasibility and their properties are determined through finite element method (FEM)-based numerical analysis. To simplify the manufacturing process and ensure chemical stability, chemically impermeable gold (Au) strips are employed around the perimeter of the structure as the plasmonic material. With effective structural parameters, the maximum amplitude sensitivity for the proposed sensor is 663.13 ${\text{RIU}}^{-1}$, the maximum wavelength sensitivity is 204,000 nm/RIU, and the maximum wavelength resolution is 4.90 × 10⁻⁷ $\text{RIU}$ for the y-polarized mode. It also shows a high linearity of 0.9849. For the detection of sucrose content, it has a maximum wavelength sensitivity of 207070.71 nm/RIU and a maximum amplitude sensitivity of 662.80 ${\text{RIU}}^{-1}$. The newly introduced sensor can detect the refractive index (RI) of various analytes across a broad spectrum, ranging from 1.28 to 1.41. This extensive detection range allows the sensor to precisely measure sucrose concentrations up to 40%. This broad range enables the analysis of various analytes like sucrose, viruses, cancer cells, proteins, and numerous others.