Advanced Photoplethysmographic Instrumentation: ZenPPG
Researchers: Mr K Budidha, Dr J May,
In recent years, photoplethysmography has generated renewed interest amongst researchers. In particular its potential use as a diagnostic tool has been demonstrated as well as the possibility of its use for measuring physiological variables beyond arterial oxygen saturation and heart rate. These variables include venous oxygen saturation, vascular tone, fluid response, blood pressure and cardiac output. Progress in these areas is dependent on the ability to record raw photoplethysmographic (PPG) signals, ideally at more than one wavelength, for real-time or retrospective analysis. This is usually achieved using a commercial pulse oximeter with analogue outputs interfaced to a data acquisition system. Alternatively researchers have developed their own measurement systems, designed for specific research projects. The zenPPG is a platform designed and developed at City University London for use by researchers which combines the advantages of standardization of instrumentation, compatibility with commercial pulse oximetry probes and the ability to customize the system for specific projects. The zenPPG system comprises two independent PPG/pulse oximetry channels which allow the raw AC and DC PPG signals to be accessed and recorded using a data acquisition system.