Development of effective photoplethysmographic measurement techniques: from contact to non-contact and from point to imaging.

This paper provides an overview of the most recent developments in photoplethysmography (PPG). Existing contact point measurement techniques, i.e. pulse oximetry probes, are contrasted with the next generation non-contact and imaging implementations, i.e. non-contact reflection and camera-based PPG. The development of effective PPG monitoring techniques relies on novel approaches to opto-physiological modeling.