Contactless measurement of dermal oxygen saturation with spatial resolution

Optoelectronic registration of dermal oxygen saturation can be done via photoplethysmographic (PPG) measurement of arterial perfusion or via measurement of the remission spectrum of vital skin. Due to their simple measurement principle and setup photoplethysmographic oxygen measurement systems have found their way to daily use in clinics and ambulances many years ago. The measured oxygen saturation is one of the most important parameters to evaluate the patient’s state of health. The used sensors consist just of two monochromatic light sources and one photo-detector and are either used in reflective or transmission mode. In the last years the Institute of High Frequency Technology (IHF), RWTH Aachen, has developed an enhancement of the PPG measurement called Photoplethysmography Imaging (PPGI) giving the possibility to measure skin perfusion contactless with a sensitive camera instead of the classical sensor. This system will also be used for the contactless measurement of dermal oxygen saturation. The concept and basic setup of this system will be described in this paper.