You'd have to keep the brain intact, and it has limited life as well. It'll expire and die no matter what. SO you'd want to "upload" your mind to an artificial brain? Tough, but that's like copying a computer program. It's an identical copy of you that will continue running exactly like you would, but the original, the thing that really was you, is dead and gone for good. You got switched off, but when your copy is switched on, your lights will stay off. To everybody in the world, even the copy, it seems as if you have just been transferred and continue living. From your point of view, you are dead.
It's a very simple concept, and requires no supernatural bogus like souls or spirit. Conciousness is just a state created by complex reactions of matter, and just because some other matter elsewhere repeats the exact pattern doesn't make the conciousness they form the exact same one.
There is no immortality unless you make the biological brain live forever.