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A wireless heart rate monitor powered by Raspberry Pi and Wi-Fi - how it works

Could Wi-Fi and a Raspberry Pi one day replace your heart monitoring wearables? These researchers say yes.

Heart rate monitoring has been a mainstay of health and fitness, and while the stethoscope has given way to more precise electronic measuring devices, they've always involved wires and straps, or, in recent years, devices worn on the wrist or finger. To verify their results, the group collected two datasets -- one using two ESP-32 Wi-Fi modules, which retail for about $5, and another using the Raspberry Pi 4B, which costs about $30 to $50. After collecting the data -- isolating the part of the CSI signal that relates to movements caused by a beating heart, removing environmental noise, applying a bandpass filter to target the 0.8 to 2.17 Hz range (corresponding to 48 to 130 beats per minute), and adding another filter to reduce noise while preserving signals needed -- the data is crunched using a a low-compute Long Short Term Memory (LSTM) neural network, and a heartbeat is literally pulled out of the air.

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