A High-Sensitivity U-Shaped Optical Fiber SPR Sensor Based on ITO Coating.

Area of Science:

• Optoelectronics
• Nanomaterials
• Biomedical Sensing

Background:

• Surface Plasmon Resonance (SPR) sensors are crucial for label-free biosensing.
• Traditional fiber optic SPR sensors face limitations in sensitivity and figure of merit (FOM).
• Indium Tin Oxide (ITO) is a transparent conductive oxide with potential for enhancing optical sensor performance.

Purpose of the Study:

• To propose and investigate a high-sensitivity U-shaped optical fiber SPR sensor incorporating an ITO coating.
• To enhance the surface electric field strength and evanescent wave-metal film interaction for improved sensing performance.
• To evaluate the sensor's sensitivity, FOM, stability, and reliability for biochemical detection.

Main Methods:

• Finite element simulations were employed to analyze the optical properties and electric field distribution.
• A U-shaped optical fiber structure was designed to optimize light-matter interaction.
• Indium Tin Oxide (ITO) was coated onto the fiber surface to enhance SPR characteristics.
• Experimental measurements were conducted to determine sensitivity, FOM, and repeatability across a specific refractive index range.

Main Results:

• Simulations showed ITO enhances surface electric field by 1.15×.
• The U-shaped ITO SPR sensor achieved a sensitivity of 4333 nm/RIU and FOM of 21.7 RIU^-1.
• The sensor exhibited excellent stability with a low relative standard deviation (RSD) of 0.4236% and minimal error.
• ITO coating demonstrated strong adhesion, ensuring long-term reliability.

Conclusions:

• The proposed U-shaped optical fiber SPR sensor with ITO coating offers superior sensitivity and FOM compared to conventional designs.
• The sensor's high performance, stability, and ease of fabrication make it suitable for high-precision biochemical detection.
• This development contributes to advancements in intelligent sensing systems for various applications.