Samsung smart watch finger can measure heart rate, wrist can't.

It's wrong. The correct way to wear it should be to stick the back cover of the watch on your arm, so that you can sense and monitor it. The wrong way to wear it will cause the wrist of Samsung smart watch to be unable to measure the heart rate. Heart rate refers to the number of heartbeats per minute of normal people in a quiet state, also known as quiet heart rate, which is generally 60 ~ 100 beats per minute, and may vary among individuals due to age, gender or other physiological factors.