Introduction . Cost-effective wearable sensors have gained increasing interest for their potential to revolutionise healthcare owing to their wide range of applications, including fitness and wellness tracking, remote patient monitoring1 , 2, early disease detection3 , 4, real-time clinical trials5 , 6 , 7, large-scale population health studies8 , 9 , 10 , 11, and personalised medicine12. Consumer-grade devices allow users to obtain summary mov...