Smartwatch blood oxygen sensors work by using light to measure oxygen levels in your blood. Here's a breakdown:
The core function of a smartwatch's SpO2 sensor is to determine the level of oxygen in your blood. It accomplishes this using a technique called photoplethysmography (PPG), which involves emitting light into the skin and measuring the light that is reflected back.
How SpO2 Sensors Function:
Here’s how the process works:
- Light Emission: The sensor on your smartwatch shines red and infrared light onto the skin, typically on your wrist.
- Light Absorption: This emitted light passes through your skin and into your blood vessels.
- Hemoglobin, the protein in your red blood cells that carries oxygen, absorbs specific amounts of these red and infrared light wavelengths.
- Measurement: The sensor detects how much light is absorbed by the hemoglobin. The SpO2 sensor passes red and infrared light into the body part that's in contact with the watch and measures how much is absorbed.
- Calculation: By comparing the absorption rates of red and infrared light, the sensor calculates the percentage of oxygenated hemoglobin in your blood (SpO2).
- Interpretation: A higher level of hemoglobin means that your blood has a good supply of oxygen.
Understanding Hemoglobin and Oxygen:
- Hemoglobin: This is the protein in your red blood cells responsible for carrying oxygen throughout your body.
- Oxygen Saturation (SpO2): This measurement indicates the percentage of hemoglobin in your blood that's carrying oxygen. A typical reading is between 95% and 100%.
- Low Oxygen Levels: Lower oxygen levels can be a sign of various health conditions and can be detected using the watch sensor.
Practical Insight:
- Placement Matters: For accurate readings, ensure the watch is snug against your wrist and positioned correctly.
- Environmental Factors: External factors such as motion, skin pigmentation, and ambient light can affect the accuracy of readings.
Table Summary:
| Feature | Description |
|---|---|
| Light Source | Red and infrared light emitted by the sensor. |
| Target | Hemoglobin in your blood. |
| Measurement | How much red and infrared light is absorbed. |
| Calculation | Percentage of oxygenated hemoglobin (SpO2) is estimated. |
| SpO2 Interpretation | A higher level indicates that your blood has a good supply of oxygen. |
