Optical heart rate sensor

Most mobile heart rate systems take their measurements from a simplified EKG circuit mounted on a breast belt. As it will be too cumbersome to ask museum visitors to don this, we decided to go for an optical sensor that clips onto a finger.


In there, the pulsing blood flow changes the amount of IR light that is reflected back to the photo transistor. The disadvantage is that this type of measurement is much more sensitive, in particular when the sensor moves against the skin.