Collins, Sunderland's current player of the year, had been in talks with the Potters late last week after the clubs agreed the fee but with reports that personal terms had been agreed prior to Saturday's clash between the buying and selling clubs, the transfer was delayed to stop his participation last Saturday.
The Potters have already signed Ben Marshall, Matt Lund, Dean Whitehead, Robert Huth, Diego Arismendi and Turkey superstar Tuncay for potential fee's of around £21m.
Collins is most comfortable at centre back but is a more than capable left back, he played there last season for the Black Cats, before moving into the cente for the first three games of this season.