Two-layer dynamic blood phantom for assessing NIRS device accuracy.

Near-infrared spectroscopy (NIRS) is a widely used non-invasive method for measuring oxygenation and hemodynamics. NIRS devices are validated using phantoms that accurately replicate the optical properties of human tissue. The aim was to develop a multi-layer blood-lipid phantom specifically to mimic the layered anatomical structure of the human head. The phantom consists of two adjustable liquid layers, which model the optical properties and dynamic characteristics of brain and superficial tissues, together with two fixed solid layers. We demonstrate our phantom capabilities by testing the INVOS 7100 and Masimo O3 NIRS devices. The phantom enabled the Masimo instrument to show that it is less influenced by superficial changes (RMSE relative to superficial layer ∼50%) than the INVOS instrument (∼35%), highlighting better depth sensitivity. This shows the phantom's value as a tool for guiding device development and evaluation.