Optical Modeling and Characterization of Lipid Emulsion Skin Phantoms for SWIR Diffuse Reflectance Spectroscopy

Skin phantoms provide an efficient way to model light interaction with the human skin. The interest in these phantoms is gaining momentum due to the growing market need for building non-invasive spectral sensors. In this work, lipid-emulsion based phantoms are investigated for the purpose of mimicking the skin in the shortwave infrared (SWIR) range of 1350 nm-2600 nm. Photonic Monte-Carlo simulations are used for modeling the lipid phantoms and to study their expected diffuse reflectance spectrum at different concentrations taking into account light absorption and scattering. Finger skin measurements for different subjects are used for comparison. SMOFlipid (20%)-based phantoms are prepared and measured at concentrations of 2% and 1% looking for the best match with the finger diffuse reflectance spectrum. A concentration of 1.3% is expected to best mimic the skin in the wavelength range of interest, in agreement with the theoretical simulations.