Rather than rely on a cumbersome sensor band, the Cardiio app (download for iPhone) uses the iPhone's front-facing iSight camera to scan your face and determine your pulse. This works because as your heart rate increases, more blood is pumped to your face, and as it is the amount of ambient light your face reflects decreases. The Cardiio app is able to detect these variations in reflectiveness and use them to determine your pulse within three beats per minutes, according to its creators, husband and wife PhD team Ming-Zer and Yukkee Poh.
The app sells for $4.99 and user reviews on the iTunes Store are largely very positive so far, with comments praising its accuracy and ease-of-use. Now, if only they could come up with an app that could scan our faces and display our cholesterol levels, we'd be all set.