The big breakthrough here is that Bluetooth LE uses a totally negligible amount of power (such that many devices can run for years on a CR2032 button cell). Al

The big breakthrough here is that Bluetooth LE uses a totally negligible amount of power (such that many devices can run for years on a CR2032 button cell). Also, you don't need to take your phone out of your pocket to tap it (it doesn't have to touch the computer, just any moderately firm object, such as a knuckle through a pants pocket).