THIS STRAP TURNS YOUR FINGER INTO A PHONE

Move over, earphones! You may soon be able to answer phone calls just by placing your finger in your ear. Thanks to a new wearable smart watch strap developed by a Korean company. 
Sgnl is a smart strap that can be attached to existing smart watch, and enables the user to answer phone calls through their finger tip. 
When you place your finger to your ear, your finger not only transmit the sound but it also block out background noise, it said 
The device receive voice signal from the phone through Bluetooth when a voice signal is received, it generates vibration through it's Body Conduction Unit (BCU) which transmit the vibration through the hand to the finger trip. 

As transmission is going on through vibration, there is no risk of harm to the human body; the company said when the finger tip is placed to the ear the vibration echoes to create amplified sound in the ear.