Recent versions of smartwatches have introduced an electrocardiogram (ECG) sensor. I'm curious about how exactly it detects electrical heart activity through the skin and what algorithms are used to convert the signal into a readable result. What are the advantages and limitations of this technology in terms of accuracy and energy consumption? Share your knowledge and experience.
How does the ECG sensor work in smartwatches?
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ECG sensors on watches detect the weak electrical potential generated by the heart using two (or three) electrodes placed on the skin. After sampling, the signal is first processed with high-pass/low-pass filtering, then converted into a heart rate curve using an R-peak detection algorithm. My watch shows noticeable noise and reduced accuracy during running, and continuous ECG measurement consumes about 10% more battery per hour. Therefore, I recommend taking measurements in a stationary state or enabling power-saving mode, only activating the ECG function when necessary.