DIY Heart Sensor with Auto-Adjusted Threshold and Heart-Shaped LED Heartbeat Indicator

I am a Biomedical Engineering (BME) graduate student at Purdue University. As a BME, I really enjoy making quick and easy projects that highlight some sort of physiological quantity. Heart rate is such an activity. There are numerous projects that deal with detecting a person’s heart beat all over the internet. I wanted to put a little spin on such projects. I have created a heart beat detector that blinks an LED when a heart beat is detected. Oftentimes with these measurements, there is a bit of threshold adjustment that takes place when designing algorithms to calculate heart rate. In many DIY projects I have seen, the threshold is manually determined and is often tuned for each person. In my project, the threshold is automatically tuned so that the circuit does not have to be re-calibrated to each user. Again, pretty simple, but fun. Enjoy!”