Tracking Human Heart Rate Without a Wearable Device
Researchers at the University of California, Santa Cruz have found a low-cost way to track heart rate via Wi-Fi and a simple microchip, which could pave the way for tracking chronic conditions like sleep apnea.
When a Wi-Fi router sends a signal to a device like a smartphone or laptop, that signal’s radio waves pass through other objects on the way. The objects absorb some of that wave, resulting in mathematically detectable changes to the wave itself.
UC Santa Cruz Ph.D. student Nayan Bhatia with a low-cost Wi-Fi ESP32 chip that works with Pulse-Fi.
Erica Cardena/UC Santa Cruz
Engineers at the University of California, Santa Cruz, have used those frequencies to simplify measurement of a basic part of human health: heart rate. A team of researchers at the Baskin School of Engineering created a system called Pulse-Fi, which uses a Wi-Fi transmitter and receiver and a machine learning algorithm trained to detect changes in frequency when the Wi-Fi signal encounters a human heartbeat. They found that the system works regardless of the person’s position or other equipment in the room, meaning that Pulse-Fi is a way to measure heart rate without a wearable, like a chest strap heart rate monitor or smart watch.
The system is accurate — tests showed Pulse-Fi measured heart rate with clinical levels of accuracy after just five seconds of signal processing; and it’s inexpensive — it was tested using ESP32 chips, which cost just $5 to $10 each, and Raspberry Pi chips, which cost about $30. The Raspberry Pis delivered better results, suggesting more expensive commercial Wi-Fi devices would be even more accurate.
Researchers are now working to see if Pulse-Fi can identify other health measures like breathing rate, which could help detect conditions like sleep apnea.
