Nano-colorimetrically determined refractive index variation with ultra-high chromatic resolution

Area of Science:

• Nanotechnology
• Optical Sensing
• Spectroscopy

Background:

• Plasmonic nanoparticles exhibit unique optical properties sensitive to their surrounding environment.
• Measuring local refractive index variations is crucial for understanding nano-environmental dynamics.
• Existing methods like handheld spectrometers can be bulky and less sensitive.

Purpose of the Study:

• To develop a front-to-end solution for sensing nano-environmental refractive index variations.
• To utilize chromaticity shifts from plasmonic nanoparticle scattering as a reporter signal.
• To optimize sensing conditions for high resolution and accuracy.

Main Methods:

• Co-projecting power combinations of RGB LEDs and digitized color grid density of CCD with various luminance.
• Mapping sensor response onto the CIE 1931 chromaticity diagram.
• Analyzing chromaticity shifts to quantify refractive index changes.

Main Results:

• Achieved a highest resolution of 0.0021 refractive index change per distinguishable color.
• Demonstrated a sensitivity 4.8 times higher than typical handheld spectrometers.
• Identified optimum conditions for nano-environment sensing through chromaticity diagram analysis.

Conclusions:

• The developed method offers a significant advancement in nano-environment sensing.
• The technique has the potential to simplify nano-sensing instruments.
• This approach is particularly valuable for multi-point and dynamic process monitoring.