One should carefully consider the advantages and drawbacks of the optical ear-lobe sensor
method when designing an application. There are some clear advantages. First of all, it is noninvasive
and the PPG signal is strong and robust. In addition, the electronic circuit is fairly
simple and small. Because there is no electrical contact to the human body it is safe and can
even be used in water. See for example the “Aquapulse” product [5]. The drawbacks,
however, are the motion artefacts and the need for a potentiometer to adjust the signal2
. The
alternative for heart-rate measurements is to use ECG and detect the heart-rate from the R-R
intervals.