MgF₂ prism/rhodium/graphene: efficient refractive index sensing structure in optical domain

Area of Science:

• Optoelectronics
• Nanotechnology
• Biosensing

Background:

• Surface Plasmon Resonance (SPR) sensors are crucial for label-free biosensing.
• Noble metals like rhodium (Rh) offer unique optical properties for SPR.
• Graphene's biocompatibility and unique electronic properties enhance sensor performance.

Purpose of the Study:

• To theoretically investigate a novel SPR-based sensing probe.
• To optimize the rhodium layer thickness and graphene layers for maximum sensitivity and detection accuracy.
• To evaluate sensor performance at different operating wavelengths.

Main Methods:

• Theoretical modeling of an SPR sensing probe.
• Utilizing a magnesium fluoride (MgF2) prism coated with rhodium and graphene.
• Simulating sensor response to varying refractive indices (1.33-1.36 RIU).

Main Results:

• Optimized probe (12 nm Rh/single-layer graphene) at 632 nm achieved ~259°/RIU sensitivity and ~0.32°⁻¹ DA.
• Optimized probe (12 nm Rh/three-layer graphene) at 532 nm achieved ~240°/RIU sensitivity and ~0.27°⁻¹ DA.
• Demonstrated the influence of graphene layers and operating wavelength on sensor performance.

Conclusions:

• The proposed Rh/graphene SPR sensor offers high sensitivity for refractive index sensing.
• Optimization of material layers and operating wavelength is key to maximizing sensor performance.
• This theoretical study provides a foundation for developing advanced SPR biosensors.