App Converts Smartphone To Clinical Thermometer

Researchers at the University of Washington have developed an app that converts common smartphones into clinical thermometers. Spotting the signs of fever early could make a difference in providing early treatment or beginning a period of isolation to reduce the chance of disease transmission. This is particularly important for viral diseases, such as COVID-19. However, many people may not have ready access to a clinical thermometer, so simply downloading an app could makes it accessible for people to take their temperature. The app relies on data from temperature sensors in the phone that normally monitor the temperature of the battery. When the phone is placed on someone’s forehead it begins to heat up, and a machine learning algorithm then calculates how much of this heat is imparted by the person touching it, allowing the app to estimate their core body temperature.

Running a fever is a common early sign of COVID-19 and many other viral diseases. However, determining if what you are experiencing is definitely a fever requires a thermometer, which many people may not have ready access to. Moreover, supplies of thermometers can run short, particularly if demand suddenly spikes, such as during the COVID-19 pandemic. Allowing people to quickly and simply determine their body temperature could be very useful, both for routine use and during future pandemics. Early identification of a fever can allow people to self-isolate earlier, helping to reduce the spread of a viral pathogen.

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“People come to the ER all the time saying, ‘I think I was running a fever.’ And that’s very different than saying ‘I was running a fever,'” said Mastafa Springston, a researcher involved in the study. “In a wave of influenza, for instance, people running to the ER can take five days, or even a week sometimes. So if people were to share fever results with public health agencies through the app, similar to how we signed up for COVID exposure warnings, this earlier sign could help us intervene much sooner.”

To this end, these researchers have created FeverPhone, a smartphone app that can convert a smartphone into a thermometer without the need to buy and install any additional hardware. The system relies on temperature sensors within smartphones that are intended to monitor battery temperatures. The technology uses these temperature data to calculate the amount of heat imparted by a user when they touch the phone to their forehead for approximately 90 seconds and then estimates their core body temperature.

In tests so far, the FeverPhone system was shown to have an average error of just 0.41 degrees F, putting it in the same ballpark as many clinical thermometers. “We started with smartphones since they’re ubiquitous and easy to get data from,” said Joseph Breda, another researcher involved in the study. “I am already working on seeing if we can get a similar signal with a smartwatch. What’s nice, because watches are much smaller, is their temperature will change more quickly. So you could imagine having a user put a Fitbit to their forehead and measure in 10 seconds whether they have a fever or not.”

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