Easy Pulse Plugin is designed for hobby and educational applications to illustrate the principle of photoplethysmography (PPG) as a non-invasive optical technique for detecting cardio-vascular pulse wave from a fingertip. It uses an infrared light source to illuminate the finger on one side, and a photodetector placed on the other side measures the small variations in the transmitted light intensity. The variations in the photodetector signal are related to changes in blood volume inside the tissue. The signal is filtered and amplified to obtain a nice and clean PPG waveform. The peak of the PPG output is synchronous with the heart beat. The following picture shows the instrumentation circuit board used for this project. It is compatible with both 5.0V and 3.3V interfaces. The operating voltage is selected by placing a 2-pin shunt jumper on JP1 header.
The details of the headers and their functions are described below.
JP3 headers are arranged in such a way that the whole module can be plugged into the left-side female headers of Arduino Uno or chipKIT Uno32 board, as shown below. Depending upon the position of the JP2 jumper, the output PPG signal can be fed to A0 or A1 analog channel of the Arduino board. If you want to use it with chipKIT Uno32 or any other 3.3V platform, make sure the JP1 jumper is placed on 3V3 position. The on-board potentiometer is useful to adjust the overall gain of the amplifier.
Easy Pulse Plugin is now also available for purchase in limited quantity on my Tindie Store.