Infrared Pulse Sensor

IR pulse sensor

I developed this breadboard version of the MAKE Weekend Projects

“The sensor itself consists of an infrared emitter and detector mounted side-by-side and pressed closely against the skin. When the heart pumps, blood pressure rises sharply, and so does the amount of infrared light from the emitter that gets reflected back to the detector. The detector passes more current when it receives more light, which in turn causes a voltage drop to enter the amplifier circuitry. This design uses two consecutive operational amplifiers (“op-amps”) to establish a steady baseline for the signal, emphasize the peaks, and filter out noise. Both op-amps are contained in a singleintegrated circuit (IC or “chip”), and hooking them up is really just a matter of interconnecting the pins correctly.”


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