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Pulse Sensor Amped is a plug-and-play heart-rate sensor for Arduino.
It can be used by students, artists, athletes, makers, and game & mobile developers who want to easily incorporate live heart-rate data into their projects.
It's quick and easy to get reliable pulse readings. Pulse Sensor Amped works with either a 3Volt and 5Volt Arduino.
The kit includes:
When the Pulse Sensor Amped is just sitting there, not in contact with any fingers or earlobes or other parts, the analog signal hovers around the mid-point of the voltage, or V/2. When Pulse Sensor Amped is in close contact with your fingertip or earlobe (or other part) the change in reflected light when blood pumps through your tissues makes the signal fluctuate around that reference point. In the image below the horizontal line is at V/2.
Arduino watches the analog signal from Pulse Sensor, and decides a pulse is found when the signal rises above the mid-point. That's the moment when your capillary tissues gets slammed with a surge of fresh blood. Then, when the signal drops below the mid-point, Arduino sees this and gets ready to find the next pulse. There's also built in hysteresis to the rising and falling thresholds which you can adjust if necessary.