Photoplethsymography for non-invasive diagnostics

Photo-plethysmo-graphy (PPG) is a noninvasive method of obtaining a signal proportional to blood volume changes using light. From the initial trials seven decades back, the PPG technique has grown leaps and bounds and today its application has become indispensible not only during surgical procedures but also in patient monitoring in critical care environment. This paper traces the path of advancement of this technique and highlights the research outcomes of an "Indo German" collaborative research between Indian Institute of Technology Madras, Chennai, India and Technical University (RWTH) Aachen, Germany funded by ministry of science (BMBF), Germany, Research projects funded by Department of Science and Technology and Department of Biotechnology, Government of India.