AFib monitor

This Wear OS app runs an algorithm for the detection of atrial fibrillation (AFib) using continuous photoplethysmogram (PPG) signals recorded from the optical sensor on the bottom of a wrist-worn device. To reduce false alarms, the app includes signal quality checks.

To function correctly for real monitoring, the watch must be securely worn on the wrist. Pressing the play/stop button starts or stops monitoring. The left button opens settings; the right button opens the heart rate chart.

At the start of monitoring, the app checks for the availability of the optical sensor. If it's not detected, users are prompted to either continue or exit. If heart rate logging is enabled, it will appear in the log screen. When AFib detection is enabled and an episode is suspected, it is shown in the log view with blue boundary lines (see screenshots). If vibration alerts are enabled, the device vibrates three times when AFib is suspected and twice when it ends. Monitoring stops automatically when the battery level drops below 15%.

Demo Mode
Demo Mode is enabled by default to allow users to preview the app’s full functionality even when the watch is not being worn. It simulates PPG signal input, demonstrating how the app would behave if an atrial fibrillation episode were detected. Users can disable demo mode in Settings to begin real-time monitoring using the device’s optical sensor.

Sensor Modes
Certain devices (e.g., TicWatch E3, Samsung Watch4) support selecting between two sensor modes in Settings. Raw PPG mode uses real-time PPG signals to calculate heart rate within the app. Heart rate mode uses values provided by the watch firmware. Raw PPG mode is recommended on supported devices like Fossil Gen 5. Signal quality may vary by hardware.

⚠️ Disclaimer: This app is not a medical device and is not intended for diagnosis, treatment, or prevention of any condition. It is provided for informational and wellness purposes only. Any suspected signs of atrial fibrillation should be confirmed with a qualified healthcare provider.

Signal quality depends on the device and how the watch is worn. It should sit firmly against the skin without excessive pressure. When signal quality is sufficient, the heart rate is displayed on screen along with a waveform, similar to the provided screenshots.

Feedback and feature suggestions are welcome.