How our Loss of Pulse Detection feature works

Loss of Pulse Detection combines signals from Pixel Watch 3’s sensors, AI and signal-processing algorithms to detect loss of pulse events, with a thoughtful design — built from user research — to limit false alarms. The feature uses signals from the Pixel Watch 3’s existing Heart Rate sensor, which uses green light to check for a user’s pulse.

If the feature detects signs of pulselessness, infrared and red lights also turn on, looking for additional signs of a pulse, while the motion sensor starts to look for movement. An AI-based algorithm brings together the pulse and movement signals to confirm a loss of pulse event, and if so, triggers a check-in to see if you respond.

The check-in asks if you’re OK while also looking for motion. If you don’t respond and no motion is detected, it escalates to an audio alarm and countdown. If you don’t respond to the countdown, the LTE watch or phone your watch is connected to automatically places a call to emergency services, and shares an automated message that no pulse is detected along with your location.

Our goal is to make a difference and contribute towards saving lives. While loss of Pulse Detection won’t detect every loss of pulse event, we believe it can make a meaningful difference, providing help when it counts most to people and their loved ones.

Loss of Pulse Detection will be available on Pixel Watch 3 in September in various countries in Europe, including the U.K., France, Austria, Denmark, Ireland, the Netherlands, Norway, Sweden and Switzerland. We’ll continue working with regulatory bodies to make the feature available in more countries.

How we developed and tested Loss of Pulse Detection

Our goal has been to build a potentially life-saving feature, and to develop it responsibly. Because loss of pulse events are timely but relatively rare emergencies, they can’t easily be observed, reproduced and tested in real-world settings. We had to find other ways to collect enough data to develop the feature to detect true loss of pulse events.