How to push key value pair to post data array Sentinel Register

Question

I created new column to my user table through database for uploading profile_pic image details but when i am trying to push upload image name to $request::all() its doesn't saves image name in database when Sentinel::register() get called other columns get filled.

$request['profile_pic'] = $safeName;

this what the way i am using to push details in $request array