Clough, sacked as Rams manager on September 28 following a 1-0 defeat at rivals Nottingham Forest after just over four-and-a-half years in charge, is keen to add to his attacking options this month and has admitted that Republic of Ireland international Sammon is on his list of potential targets.
"We have made enquiries. Many of the enquiries we've made want to get the weekend and the FA Cup games out of the way first," said Clough, speaking after the Blades' 2-1 defeat at Walsall on New Year's Day.
"We have a long list of names and Conor Sammon is on that list. But the list is about 15 names long. In fact, any striker in the Championship that isn't currently in the starting XI - and who interests us - we will be making an enquiry."
As Derby manager Clough signed former Kilmarnock striker Sammon from Wigan for a fee of around B£1.2million.
Sammon was a regular under Clough but the 27-year-old has found starting opportunities hard to come by since Steve McClaren replaced him at the Championship club.
Clough, appointed Blades boss in October, also last month went public with his interest in another Derby forward - Johnny Russell.