Newcastle University's Conor O'Neill, who carried out research into the effects of a bomb blast inside a train carriage, said using special materials could prevent shrapnel injuring passengers.
More top news
George Michael died in December last year at the age of 53.
PC Keith Palmer, 48, stabbed by Khalid Masood while on duty in the grounds of the Palace of Westminster last Wednesday.
Those gathered on the bridge fell silent at 2.40pm - the time the first call was made to police exactly seven days ago.