How Google built a body temperature feature for its Pixel thermometer app

The Google Health team has developed a new body temperature feature for the Pixel 8 Pro phone, which allows users to measure body temperature by scanning a person’s forehead with their phone. The feature is part of the Thermometer app and provides accurate temperature readings within a range of 96.9°F – 104°F (36.1°C – 40°C) to within ±0.3°C, making it as accurate as other temporal artery thermometers. The feature was developed by Ravi Narasimhan, who created a miniaturized device with an infrared sensor for body temperature measurement, which eventually evolved into a feature for the Pixel phone. The body temperature app has received FDA’s De Novo classification, making it the first for smartphones in the U.S., and is now available on the Pixel 8 Pro.

The Pixel 8 Pro team added an infrared sensor next to the rear camera to power the body temperature feature. By pointing the rear camera at the forehead and sweeping across, the app accurately measures body temperature by scanning the temporal artery, as opposed to less accurate forehead thermometers that are pointed at the center of the forehead. The data from the infrared sensor is passed to an algorithm to calculate the temperature that will be displayed on the device, powered by the Tensor G3 chip. The infrared sensor’s wide field of view can sense heat beyond the forehead when the phone is too far away, so it is important to be close to get an accurate reading.

Overall, the body temperature feature is convenient and accurate, as it eliminates the need for an additional device and provides temperature measurements comparable to traditional temporal artery thermometers. The development of this feature has opened up new possibilities for health tools on smartphones, and the implementation of the infrared sensor and algorithm for temperature measurement has paved the way for potential future health-related features.


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