Near-Infrared Diffuse Reflectance Measurement Method Based on Temperature-Insensitive Radial Distance

Area of Science:

• Optical sensing
• Biomedical optics
• Spectroscopy

Background:

• Temperature fluctuations are a major source of error in near-infrared (NIR) diffuse reflectance measurements.
• Accurate detection of analytes like glucose is crucial for various applications, including medical diagnostics and industrial process monitoring.

Purpose of the Study:

• To propose and validate a novel measurement method using temperature-insensitive radial distances to mitigate temperature interference in NIR diffuse reflectance.
• To enhance the accuracy of glucose concentration detection in Intralipid solutions under varying temperatures.

Main Methods:

• Analytical solution of the steady-state diffusion equation was used to deduce temperature-insensitive radial distances.
• A detection system was designed to measure diffuse reflectance in 3% Intralipid solutions across various glucose concentrations (0-100 mM) and temperatures (35-40 °C).
• Comparison of glucose information extracted at different radial distances under fluctuating and constant temperatures.

Main Results:

• Theoretical and experimental findings confirmed the existence of temperature-insensitive radial distances within specific wavelength ranges (1000-1340 nm and 1440-1600 nm).
• These identified distances showed minimal sensitivity to glucose concentration variations.
• Diffuse reflectance measurements at temperature-insensitive radial distances yielded a significantly stronger correlation with glucose concentration, closely matching results obtained under constant temperature conditions.

Conclusions:

• The proposed temperature-insensitive radial distance method effectively reduces the impact of temperature variations on NIR diffuse reflectance.
• This approach is expected to substantially improve the accuracy of diffuse reflectance measurements for biological tissues and industrial materials.