A Handheld Multispectral NIRS Device for Real-Time Baseline-Relative Monitoring of Tissue Oxygen Saturation

This MATLAB code estimates tissue oxygen saturation (StO₂) from multispectral reflectance data collected using the PhasorDetect handheld NIRS device. It performs wavelength-wise calibration, melanin absorption correction based on Fitzpatrick skin type, and applies the Modified Beer–Lambert Law (MBLL) to recover oxy- and deoxy-hemoglobin concentrations. The script compares estimated StO₂ values with reference measurements from a Hutchinson InSpectra monitor, computing accuracy metrics (MAE, RMSE, SD, correlation) and generating Bland–Altman plots