article_snippet: In particular, the bracelet contains a HeartID sensor that measures the amount of electrical power generated by a human heart, called a cardiac rhythm tracked on an electrocardiogram, or ECG.
article_snippet: ECG differs from person to person and depends on the location and size of the their heart.
article_snippet: the bracelet contains a HeartID sensor that measures electrical power generated by a human heart tracked on an electrocardiogram, or ECG .
article_snippet: It can therefore adjust to typical variations in heart rate, even if the wearer has an irregular ECG as a result of a medical condition.
article_snippet: An ECG differs from person to person and depends on the location and size of the their heart.
highlights_snippet: It reads the wearer's cardiac rhythm, which is said to be as unique as a person's fingerprint, to authenticate who they are .
  
highlights_snippet: This is called a cardiac rhythm and is tracked on electrocardiogram (ECG)
  electrocardiogram (ECG)
   
highlights_snippet: differs from person to person and depends on size of This heart .
  