With the Apple Watch launching this Friday, Apple has been releasing more details about their new smartwatch and now the company has released some details on how the heart rate monitor on the device works.
One of the main features on the new Watch will be health and fitness monitoring and now Apple has revealed how the heart rate monitor works.
The heart rate sensor in Apple Watch uses what is known as photoplethysmography. This technology, while difficult to pronounce, is based on a very simple fact: Blood is red because it reflects red light and absorbs green light. Apple Watch uses green LED lights paired with light‑sensitive photodiodes to detect the amount of blood flowing through your wrist at any given moment. When your heart beats, the blood flow in your wrist — and the green light absorption — is greater. Between beats, it’s less. By flashing its LED lights hundreds of times per second, Apple Watch can calculate the number of times the heart beats each minute — your heart rate.
You can find out more details about the heard rate monitor and also other health an fitness features on the Apple Watch at the link below.