Monte Carlo simulation of light scattering in tissue for the design of skin-like optical devices.

Measurement techniques based on optics, with the characteristics of noninvasive or non-destructive detection and high accuracy, offer excellent properties for application in various scenarios. Skin-like optical devices capable of deforming with human skin play major roles in future biomedical applications such as clinical diagnostics or biological healthcare. Unlike traditional rigid devices, the skin-like optical device is conformal to the skin because of the flexibility and stretchability. However, the detected signals based on light intensity are very sensitive to the light path. As a result, the accuracy and efficiency of the skin-like device will be influenced owing to deformation. In this work, for optimizing the design of the skin-like optical device, we use the Monte Carlo method to investigate the light distribution after scattered and absorbed by a human tissue. Different parameters of light source and blood vessels are used to simulate the device and human tissue deformation respectively. The characteristics of the exited light are then summarized and analyzed to study the influence of the deformation. The simulation shows that the deformation of the device and human tissue will produce non-linear effects on the characteristics of the exited lights. Finally, we design and fabricate a skin-like device using the simulation results and use it to monitor photoplethysmogram signals. This work will aid in the design of skin-like optical devices in the future.