I’ve got a heart rate monitor, but it’s tied to a strap that connects wirelessly to my Garmin 500 cycling computer. There are also numerous smartphone apps which can measure your pulse when you cover up the camera and flash with your fingertip. But the Cardiio app for iOS uses MIT technology to measure your heart rate without even a touch, simply by “looking” at your face.
Cardiio measures when your face is reflecting more light and when it’s not, giving you a semi-accurate idea of what your heart rate is without having to strap a sensor to your wrist or chest. The slight increase in blood volume to your face whenever your heart beats causes more light to be absorbed, hence it is less reflected. Using this, the app tracks these changes and calculates your heart rate.
According to one study, the technology is accurate to within 3 beats-per-minute of a clinical pulse oximeter in a well-lit environment. Cardiio is available through iTunes for $4.99 (USD), and is compatible with the iPhone 4/4S, iPad 2 and above and 4th gen iPod Touch.