➀ Researchers at UC Santa Cruz developed Pulse Fi, a system using WiFi signals to measure heart rates without wearables, achieving ≈0.5 BPM error across multiple body positions;
➁ The low-cost system combines ESP32 chips ($5-$10) and Raspberry Pi with machine learning to filter heartbeat signals from WiFi variations, working up to 3 meters away;
➂ Trained using oximeter-correlated datasets, the technology enables accessible health monitoring for homes and resource-limited environments.