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- Heart rate data can be obtained from Wi-Fi CSI signals.
- Tested with ESP-32 modules and Raspberry Pi hardware.
- Accuracy reached 99.81% compared to medical methods.
Heart rate monitoring has been a staple of health and fitness, and while the stethoscope has given way to more accurate electronic measuring devices, they have always involved wires and straps or, in recent years, devices worn on the wrist or finger .
But what if there was a way to measure your heart rate wirelessly… via Wi-Fi?
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That’s exactly what researchers at the University of California have recently uncovered.
Non-intrusive, continuous monitoring system
Using the way Wi-Fi signals travel through the environment, they analyzed how a beating human heart affects channel state information (CSI—the part of a Wi-Fi signal that contains information about how the signal travels from transmitter to receiver).
They came up with a non-intrusive, continuous heart rate monitoring system called Pulse-Fi.
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It was so interesting that I had to buy the paper to look at, and it’s quite fascinating.
To test their results, the group collected two datasets—one using two ESP-32 Wi-Fi modules that retail for about $5, and another using a Raspberry PI 4B that costs about $30 to $50.
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Data collected using Wi-Fi was compared with data collected simultaneously using traditional methods.
After data collection—isolating the portion of the CSI signal that relates to the movements caused by the beating heart, removing environmental noise, applying a band-pass 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 the noise while preserving the signal—we use a low-cost AA to reduce the signal that is low , using
But how accurate is impulse-fi?
Highly accurate. The researchers found that using ESP-32 modules, they could achieve 99.38% accuracy, or an error of 0.51 bpm, compared to traditional heart rate measuring technology, and 99.81% when using a Raspberry Pi, with an error of just 0.2 bpm.
This is clinical-grade accuracy.
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The increased accuracy of the Rasen PI is due to the Wi-Fi module having more subcarrier frequency channels than the ESP-32 module (234 compared to 64). And this accuracy requires only five seconds of data collection using only off-the-shelf parts.
Will Pulse-Fi replace how heart data is collected?
Probably not right now, but it opens up new possibilities in both medicine and health.
