Engineers used artificial intelligence (AI) and inexpensive, off-the-shelf hardware to convert the amplitude of Wi-Fi signals into estimates of a person's heart rate. The accuracy of this system, called Pulse-Fi, is remarkably consistent across body positions and distances, the researchers wrote in a study published Aug. 5, 2025.
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The results show that reliable heart rate information can be extracted contactlessly using pre-existing infrastructure and Wi-Fi hardware, study authors Pranay Kocheta, Nayan Bhatia and Katia Obraczka Live Science in a joint email. Obraczka is a professor of computer engineering at the University of California, Santa Cruz (UC Santa Cruz), Bhatia is a doctoral student in computer science at UC Santa Cruz, and Kocheta is a high school student who conducted the research during an internship.
Many technologies used at home, such as chest strap monitors and smartwatches, monitor vital signs, including heart rate and breathing rate. However, these devices require constant contact with the person and are expensive, leading to the need for contactless technologies.
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Such technology can leverage the information in Wi-Fi signals, which are radio waves that carry data between a transmitter and a receiver, such as between a router and a computer.
“Channel state information” (CSI) provides the amplitude and phase of the signal as it travels between these two devices, including when it passes through obstacles. Because signals are distorted when they pass through these obstacles, researchers can filter the CSI data to capture the vital signs.
There are now several examples of Wi-Fi heart rate detection, but Kocheta and his team argued that there are still several limitations. For example, many rely on now-defunct hardware. To address these limitations, the researchers developed the new system called “Pulse-Fi.”.
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To collect the data needed to evaluate Pulse-Fi, the team placed seven people between two ESP32 devices with an antenna. These microcontroller devices emitted Wi-Fi signals, with one acting as a transmitter and the other as a receiver. The participants’ actual heart rates were simultaneously recorded via a pulse oximeter attached to their fingertips.
