Photoplethysmography: Light Emitter Diode Wavelength Derivation from the Absorption Spectra of Haemoglobin

It was demonstrated by the World Health Organisation (WHO) in 2017 that the Cardiovascular Diseases (CVD) is the main cause for deaths globally. Since the CVD is directly related to the human circulatory system in which the heart acts as a pump to push the blood fluid into the system thereby facilitating and allowing fluid flow, in this close circuit system, if the heart is well monitored it will be easy to perceive any malfunctioning of the system on time and take necessary action before it is too late. In the attempt to contribute toward this alarming issue, this work seeks to contribute a Photoplethysmography (PPG) heartbeat sensor design that applies an efficient derivation approach to sensing of optimal wavelengths. There exists few PPG heartbeat sensor design in the literature. Beside the fact that the choice of the operating wavelength selection is of prime importance for good PPG signal sensitivity and detection, most of these works do not clearly explain how and why a specific wavelength was derived. Hence, this work proposes an efficient practical strategy of the transmitter Light Emitter Diode (LED) wavelength derivation based on the molar extinction coefficient from the absorption spectra of the haemoglobin.