Default Software Write Blocker for Android

Hi,

In my university project for Android Forensic I would like to implement a simple software write blocker so that I can image Android device with out any modification to Android device.

I need your help to achieve this.

I would like to know ground level functionality of software write Blocker for Android?

A guidance to start implementation of a simple software write blocker.

Thank you very much for any kind of assistance for this.
iua