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Track your heart rate from your bag or your pocket with your smartphone

No wrist real estate? No problem. If you want to reserve the precious space on your forearm for bangles, bracelets, and actual watches, but still want an accurate fitness tracker, prepare to rejoice — the brilliant minds at MIT are hard at work on a project they’re calling BioPhone, which can actually track your heart and breathing rates even if your smartphone is in your pocket or bag. By relying on smartphones’ built-in accelerometer, Javier Hernandez of MIT notes that the body’s biological signals and micromovements can actually be captured without a wrist-bound wearable.

According to initial results from Hernandez’s team published in August, “motion sensors available in off-the-shelf smartphones can capture physiological parameters of a person during stationary postures, even while being carried in a bag or a pocket.” In their experiments, MIT researchers have managed to “develop methods to extract heart and breathing rates from accelerometer data and compare them with measurements obtained with FDA-cleared sensors.”

While their goals are lofty, though, early prototypes haven’t proven to be all that accurate. In comparison to other fitness trackers, BioPhone’s heart rate estimates were off by a margin of about one beat per minute, while breathing rates differed by around a quarter of a breath per minute. When normalized over the course of a day, these small errors add up.

Of course, Hernandez recognizes that there are still significant challenges to be addressed. His team has yet to determine how best to measure these vital signs when sensors are not placed particularly close to the heart or a pulse. But even so, with improvements being made on a seemingly daily basis to smartphone sensors, it may not be inconceivable that in-pocket fitness trackers could be available in the near future.

“Currently, most smartphone users are not aware that cardiovascular health information can be conveyed simply by carrying or holding a smartphone that contains accelerometers,” Hernandez wrote in his study. “Findings like the ones presented in this work urge us to reconsider how this type of data is monitored, stored, and transmitted to enforce transparency and protect user’s privacy of their health-related data.”