Optical heart rate sensors use green LED lights to measure blood flow and heart rate through the skin.

Accelerometers measure acceleration and are used to track steps, distance, and other movement-related metrics.

Gyroscopes measure angular velocity and are used to track orientation and position.

Barometers measure air pressure and are used to estimate altitude.

Accelerometers can detect sudden changes in movement and are used to identify falls and other safety-related events.

Proximity sensors detect when an object is near the smartwatch and are used to enable gestures and other touchless interactions.

Accelerometers can detect subtle movements associated with different sleep stages and are used to track sleep patterns.

SpO2 sensors measure blood oxygen saturation levels and are used to monitor oxygen levels in the blood.

PPG (photoplethysmography) sensors measure changes in blood volume and are used to estimate blood pressure.

GPS sensors are used to track the location and distance traveled by the smartwatch wearer.

Infrared sensors measure skin temperature and are used to track body temperature and detect fevers.

ECG (electrocardiogram) sensors measure the electrical activity of the heart and are used to detect heart rhythm abnormalities.

EDA (electrodermal activity) sensors measure changes in skin conductance and are used to estimate stress levels.

Microphones are used to enable voice commands, phone calls, and other audio-based interactions with the smartwatch.

Glucose sensors are used to measure blood glucose levels and are particularly useful for individuals with diabetes.