It feels like it's only a matter of time until Apple jumps into serious health tracking, especially as the Apple Watch Series 3 has seemingly been a massive hit for the trillion dollar company.
Way back in 2016, Apple applied for a patent called "Apple Invents a New Health Wearable Device That Measures Electrocardiogram Signals". That patent has finally been granted, and it hints at a future of Apple wearables beyond the Apple Watch.
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As described back in 2016, the patent covers a wearable that you would not just wear on your wrist. You could also wear it on either ankle, and the device would identify which limb it was on and collect electrocardiogram (ECG) readings.
The patent also points to the ability for the device to perform calculations to adjust the ECG readings to make sure they're correct. Because it can collect data from either wrist or either ankle, the device needs to make sure it's consistent. You wouldn't want to put it on your ankle and get one ECG reading and then put it on your wrist and get another one. The device basically levels them out and gives you a true ECG reading that you don't have to think about.
The bigger question is whether this patented new wearable ever comes to fruition. It's certainly possible that Apple could make a more dedicated health wearable, especially because selling a mass market device that goes through FDA regulations would be quite a pain for Apple.
However, back in October 2017 it was reported that Apple was already working on an Apple Watch with a built-in ECG. We don't exactly know when that ECG sensor could make its way onto an Apple Watch. Could it be this year with the Series 4, or could it be later down the line?