When Apple releases Apple Watch and Apple Watch Sport in April, expectations will be high. Today, over a dozen watches attempt to monitor heart rate through the wrist, using optical sensors to judge changes in blood flow, but only a few actually work well. It's a tricky engineering problem. Comb the reports of the most thorough gadget reviewers, and you'll see that many of Apple's competitors simply don't have their sensors quite working. The watches stop monitoring if the user is cold or moving around (which can sometimes happen in sports.)
Imagine getting to work Monday morning and a project manager demands that you reverse-engineer a difficult technology in a newly minted field. Optical heart rate feels a little like light-bulb filaments in the 1870s: everyone's trying to find a long-lasting one, only a few have the answer. In wearable products, the pulse is an important data stream to power a lot of advanced features.
To date, several companies have completely figured out optical heart rate monitoring for wearables, including Mio and Valencell. Will Apple join them in April, or will its users discover a finicky and imperfect version?