Sensors for Heart beat Monitor

[bhaazee]

I have been able to find small heart beat sensors (in the size of wrist watches). I would like to know what kind of sensors are employed in this watch?

 

Regards

[CaptainPanic]

I'm guessing that it might be a type of piezoelectric sensor (also called a piezo element) right under the cover of the watch. But please note that I am no expert in the field of heart beat sensors.

[Enthalpy]

The beat sensors clipped to patients' ear or finger observe the flesh optical transparency change as blood flows in surges. One more possibility, at least at the ear or the finger of a non-mobile person.

[bhaazee]

Actually I wanted to know, how the small movements of hearbeat are measured.

 

Even small flex resistors would serve the purpose (I believe so)

 

Thnx to both of you for the replies.