  Wearable devices are increasingly being used for monitoring health signals
and for fitness purposes with typical uses being calorie tracker, workout
assistant, and step counter. Even though these wearables can measure many
health signals (e.g. heart rate), they are still not perceived as highly
accurate, relative to clinical monitoring devices. In this paper, we
investigate the accuracy of heart monitor as included in two popular wearables
Motorola Moto 360 and the Apple Watch. We analyze the accuracy from a hardware
and a software perspective and show the effects of body motion on the heart
rate monitors based on the use of photoplethysmography (PPG) signals used in
Android wearables. We then do a software reliability study of the Android Wear
OS, on which many wearables are based, using fuzz testing.
