Techniques of Recording Photoplethysmographic Signals

Abstract

The photoplethysmography optically measures blood volume changes within micro vascular tissue. Furthermore, photoplethysmographic signals are used within pulse oximeters in order to calculate the oxygen saturation of the blood. This standard measurement technique is performed as a non-invasive spot check method for human health conditions in hospitals or other health care facilities. Usually at least two light sources are used alternating in order to measure photoplethysmograms at different wavelengths. In this paper we will investigate different methods of optically recording photoplethysmographic signals.

Keywords

• photoplethysmography
• pulse oximeter
• hardware controlled photoplethysmography
• constant current
• constant intensity
• amplitude modulation