Optical

PPG

Photoplethysmography

Optical sensor that measures blood volume changes to derive heart rate and SpO2

How It Works

Shines LED light into skin and measures the amount reflected back. Blood absorbs light differently based on oxygen levels and pulse.

What It Measures

Heart Rate

Beats per minute measured at rest or during activity

Primary HR source for most wearables

bpmVitals

Heart Rate Variability

Variation in time between heartbeats (RMSSD)

Derived from pulse intervals

msCardiovascular

Blood Oxygen

Peripheral oxygen saturation level

Using red and infrared wavelengths

%Vitals

Respiratory Rate

Breaths per minute

Derived from PPG waveform

brpmVitals

Devices with PPG (5)

Apple

Apple Watch Series 10

Smartwatch

$399+

Oura

Oura Ring 4

Ring

$349+

Samsung

Samsung Galaxy Ring

Ring

$399

Samsung

Samsung Galaxy Watch 7

Smartwatch

$299+

WHOOP

WHOOP 5.0

Fitness Band

$199+

Quick Stats

Type: Optical
Devices: 5
Measurements: 4

Sensor Type

Optical

Light-based sensors including PPG for heart rate and SpO2 measurement

Measurements

Heart Rate Heart Rate Variability Blood Oxygen Respiratory Rate