A new authentication system uses your heart’s shape and pulsations as a unique biometric to identify and authenticate you. The new system makes use of low-level Doppler radar to wirelessly and continuously map out the dimensions of your beating heart, granting you access to your device so long as you’re near it. The system takes about 8 seconds to scan a heart for the very first time, and after that, the system continuously recognises your heart, making sure another user has not stepped into your device.
Source: https://thehackernews.com/2017/09/cardiac-scan-heart-password.html