At its most basic, self-awareness is all about observing oneself from within.
Before about 18 months old, infants don't appear to be aware that other people can have separate points of view from their own (e.g. "Is Mummy hungry?" only makes them examine whether they themselves are hungry).
Then there's a period when they can understand that other people / things have different stories than their own (e.g. Giving bunny a pretend bath in an empty box).
Later still comes the ability to recognize that a story's narrative can be mapped back onto oneself (e.g. Answering "When will you be hungry?").
IMHO, a "conscious machine" should minimally be able to describe its ability to be self aware.
A key part of consciousness appears to be story narratives, and their manipulation.
Neurons appear to be an unlikely substrate for doing this efficiently.