Easy Pulse Plugin: open source Arduino compatible oxymeter

By on September 4, 2015
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Yesterday we talked about Hackaday Prize 2015, here’s one of the really interesting projects presented: an open source Arduino compatible PPG Oxymeter. Good luck to Rajendra Bhatt!

Easy Pulse Plugin is an open-source pulse sensor based on the principle of photoplethysmography (PPG), which is a non-invasive technique of measuring the cardiovascular pulse wave by detecting blood volume changes in the blood vessels close to the skin. This sensor applies the principle of PPG to the tip of a finger using an infrared light emitting diode (IR-LED) and a photodetector. Easy Pulse Plugin provides all necessary instrumentation and amplification on board to retrive a filtered cardiovascular pulse signal from the photodetector output. The power supply and output pins of Easy Pulse Plugin are accessed through standard 0.1″ male header pins. They are arranged in an Arduino-friendly fashion so that it can be directly plugged into the left female headers of Arduino Uno (or any other compatible) board for easy interfacing. It operates at both 5.0V and 3.3V, and is also breadboard-friendly to work with other platforms.

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.

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.

Source: Easy Pulse Plugin

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