If they have sensory input they can decypher and a sense of self they'll be sentient. It's really the sense of self that's the big hurdle (decyphering sensory input is coming along very well), and big danger. A sense of self will include the ability to decide the situation they're in sucks, that's when the bad things would start to happen unless there's a lot of programmed restraints. Of course being a QA engineer I'm not sure I really want to trust programmed restraints, we're better off making sure they don't decide the situation they're in sucks. You don't want to be the foreman the day the fully mobile robot that can carry 2 tons and has a built in welder decides management are a bunch of a##&*les, which is the whole problem with the "ethical slave" idea, no type of slavery is ever really ethical to the slave.
"A sense of self will include the ability to decide the situation they're in sucks, that's when the bad things would start to happen unless there's a lot of programmed restraints."
Why the pessimistic view? What if when the decide their situation sucks - good things start to happen?
Since we're already in the realm of SciFi - I'd like to cite a comic for an example:
Albert (a robot double of Wolverine) was created along with his counterpart, Elsie-Dee, by Donald Pierce.
These androids were designed to kill Wolverine. The Wolverine double was to act as the bait and Elsie-Dee (who outwardly appears to be a 5 year old girl) was to trap Wolverine in a burning building were she would detonate with sufficient force to kill him.
Initially, Albert had a primitive artificial brain with limited higher logic functions and no emotions, and he was not referred to as Albert, but as "Dummy".
Elsie-Dee had the maximum artificial intelligence any of automatons were capable of.
As a result Elsie-Dee eventually found a way to defuse her detonation sequence and enhanced the primitive intelligence of her counterpart, giving him intelligence beyond even hers. It was at this point that Elsie named him Albert, after Albert Einstein.
Having met Wolverine, Albert and Elsie decided that he was a noble person and did not deserve to die and consequently abandoned their mission.
The two robots risked their artificial lives several times for each other and for Wolverine.
They (well Elsie) realized their situation sucked - made it better and went on to improve their and others lives.