High sensitivity tapered fiber refractive index biosensor using hollow gold nanoparticles.

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Optical Sensing

Background:

• Localized Surface Plasmon Resonance (LSPR) sensors offer label-free detection.
• Optical fiber biosensors are advantageous for fast, accurate, and low-cost disease diagnosis.
• Hollow gold nanoparticles (HAuNPs) can be utilized for enhanced refractive index sensing.

Purpose of the Study:

• To present a tapered optical fiber (TOF) sensor functionalized with HAuNPs for refractive index (RI) measurement.
• To investigate the sensor's performance for label-free biosensing applications, specifically for cancer cell detection.
• To optimize sensor design parameters for improved sensitivity and performance.

Main Methods:

• Sensor simulation using the finite difference time domain (FDTD) and finite element method (FEM).
• Investigating the effects of HAuNP dimensions (thickness, diameter) and TOF waist diameter.
• Analyzing the transmittance spectrum for RI changes.

Main Results:

• Achieved a wavelength sensitivity of 489.8 nm/RIU and a Full Width at Half Maximum (FWHM) of 50 nm with optimized HAuNP and TOF parameters.
• Demonstrated a 2-3 times increase in sensitivity compared to similar sensor structures.
• Validated the sensor's capability for label-free detection of cancer cell refractive index.

Conclusions:

• The developed TOF-HAuNP sensor is a promising candidate for sensitive and label-free refractive index biosensing.
• The sensor enables non-invasive, early-stage cancer detection through analysis of human blood samples.
• Optimized design parameters significantly enhance sensor performance for biomedical applications.