The science behind the Cardiio is almost as fascinating as the concept itself. Poh's algorithm captures a video of the user's face with the help of a tracking software before distilling it into RGB channels which are, in turn, analyzed to determine a rough BPM based on reflectivity.

And it's surprisingly accurate. At least that the technology behind Cardiio is accurate to within three beats per minute. You might not see it at your doctor's office, but it could be useful for tracking your heart rate when you exercise.

Cardiio isn't Poh's first attempt at using light to measure heart rate, but it's probably the most popular. , even though it's only been around for a few days, Cardiio is already one of the most highly rated health and fitness apps on iTunes. Arguably, it's also one of the creepiest--Cardiio will, among other things, attempt to provide you with your estimated life expectancy. Eek.

[ via ]

Cassandra Khaw is an entry-level audiophile, a street dancer, a person who writes about video games for a living, and someone who .