Optical signals. Open knowledge.
Green light · 530 nm
Each heartbeat changes blood volume in the tissue. A sensor detects the resulting changes in light.
01 / THE WORKFLOW
From first principles to your next experiment.
*Infrared is invisible; violet is false color. Conceptual paths, not to scale. Sampling depths overlap and vary with tissue and sensor geometry.
FIELD NOTES / 001
Light scatters. Blood absorbs. A detector catches a small part of the returning light—and its subtle changes with each pulse.
Explore the anatomy behind the waveform, from the blood-free epidermis to the vessels beneath it.
Read the PPG primerLight, tissue, and the shape of a pulse. Build an intuition for the science behind optical sensing.
Learn PPGExplore anatomy, wavelengths, and simulated signals in Plethscape, our interactive teaching lab.
Explore PlethscapeExperiment with camera-based PPG in the browser using the open-source ppg-js library.
Discover ppg-js02 / FROM THE LIBRARY
POPULAR GUIDES
DATASET GUIDES
03 / THE RESEARCH ATLAS
Find foundation models, explore the datasets behind them, and follow the papers back to their sources. A connected view of a growing field.
Explore the research atlasPPG measures changes in light interacting with tissue. What we infer from it depends on the sensor, the person, and the conditions. Our guides help you explore those connections. Follow the original sources, read results in context, and treat simulations as teaching tools. About the library ↗
