Journal of medical signals and sensors
Simulation of Photoplethysmography Signal in Reflection Mode Using Three-layer Skin Optical Modeling
By Afzalipour R, Latifi AR, Rezaei-Latifi A and 2 others.
Abstract
Background
Photoplethysmography (PPG) is an optical, noninvasive method widely applied to detect changes in blood volume within the skin. Accurate modeling of light-tissue interaction is essential for improving PPG sensor design and signal interpretation.
Methods
In this study, the three main layers of human skin were simulated using the nonsequential mode of Zemax optical software. Each layer was assigned specific optical properties to accurately represent physiological conditions. A light source with a wavelength of 600 nm was directed onto the modeled skin, and the propagation of light through the tissue to the photodetector was simulated. The direct current (DC) component of the PPG signal was first modeled, representing the baseline optical response. Then, the alternating current (AC) component (pulsatile component linked to cardiac blood-volume changes) was added by simulating periodic changes in blood volume within the dermal vessels during cardiac cycles.