This seminar will discuss the basic principles of photoplethysmography (PPG), the physiology involved and methods for measurement. Attendees considering a new wearable design will gain insights on the system design trade-offs, with real data backed by simulations, whereas those interested in low-power wearables will learn simulation and electronics design techniques for extending the life of their product. Engineers interested in physiological monitoring will benefit from this in-depth technical tutorial of the entire opto-electrical system for heart rate and pulse oximetry.