Logo of the Physikalisch-Technische Bundesanstalt

Development of methods for the determination of oxygen saturation in the human brain


The Department of Biomedical Optics has started a technology transfer collaboration with NIRx-Medizintechnik GmbH. This involves the development and testing of wearable devices for determining oxygen saturation in the human brain. The measurement method is based on the application of near-infrared light. The devices were extensively characterized at PTB. Reference phantoms developed by PTB with optical properties similar to those of tissue were used for this purpose. These properties (absorption and scattering) are known from internal measurements with the time-resolved measurement method, which is considered the gold standard. One focus of the jointly conducted investigations was the optimization of the probe configuration at the head. Furthermore, evaluation procedures were developed based on the application of the diffusion model for the propagation of light in tissue. Among other things, it became apparent that the spatial separation of the two near-infrared light sources must be taken into account. In order to evaluate the influence of the approximations in the diffusion model, various theoretical investigations were carried out using a Monte Carlo model for light propagation in tissue. By using layered structures in the simulations, the depth sensitivity of the different probe configurations was also determined.