Vivo uses Synaptics’s solution which is an optical-based sensor that works underneath an Organic Light-Emitting Diode (OLED) display.
https://en.dailypakistan.com.pk/technology/vivo-unveils-worlds-first-in-display-fingerprint-scanning-smartphone/
The new phone equipped with 6.43 inch of FullView AMOLED display and a 2.2GHz Snapdragon 660 processor with 4GB of RAM and 128GB of onboard storage.
For imaging, it features 24MP + 5MP dual-cameras at the rear, while the front comes with a 24MP selfie shooter. Powering the device is a 3,800mAh battery which supports fast charging.
It runs on Android 7.1.2 in Vivo's FunTouch OS skin on top.