Ear-o-smart is a crowdfunded smart earring that monitors heart rate, calories, and activity level. Its sensor is combined with a changeable earring. Its app, via voice instruction, tells wearers to speed up or slow down based on heart rate data.

The tiny wearable was created by minimizing PPG Technology and Bluetooth data transfer. PPG Technology gauges heart rate through infrared light that blood reflects if present under the skin. The sensor works better if worn on the earlobe than on the wrist, as the many blood vessels in the ear make PPG more effective.