Tonge, a Blades player for eight years before signing for Stoke in 2008, has joined Derby on loan from the Potteries club for the remainder of the season.
He could replace Lee Johnson in the centre of midfield after the diminutive playmaker returned to Bristol City following the conclusion of his loan.
Another deadline-day recruit - Manchester City defender Javan Vidal - is expected to be included in the squad after arriving on a loan deal until the end of the campaign.
A further change to Nigel Clough's squad is the departure of DJ Campbell. Last weekend's victory over rivals Nottingham Forest was the final game of his loan spell and the Leicester striker has since joined Blackpool on loan.
Defender Dean Leacock (knee) and midfielders Lee Croft and Lee Hendrie (both hamstring) are expected to remain sidelined.
