A watch measures blood pressure primarily using a technique called photoplethysmography (PPG).
The Technology Behind Blood Pressure Measurement
Smartwatches capable of blood pressure measurement utilize a non-invasive method involving light. According to the provided reference, a technique called photoplethysmography (PPG) allows the watch to emit light into the skin and measure changes in light absorption to calculate blood pressure. This process leverages the fact that blood absorbs light differently than surrounding tissues, and the volume of blood in the blood vessels changes with each heartbeat.
How the Measurement Works
Here's a breakdown based on the PPG technique described:
- Light Emission: The watch emits light (often green or infrared) into the skin.
- Light Absorption Measurement: Sensors on the watch measure how much of that light is absorbed by the blood flowing in the vessels beneath the skin.
- Detecting Changes: As blood pulses through the arteries with each heartbeat, the volume of blood changes, leading to detectable changes in light absorption.
- Calculation: The watch uses sophisticated algorithms to analyze these changes in light absorption patterns over time and calculate blood pressure.
The entire process is quite rapid. It typically takes only 30 seconds or less to get a blood pressure reading using this technology.
This method provides a convenient way for users to monitor their blood pressure trends directly from their wrist.
