Environment status chip
From Tardis Wiki, the free Doctor Who reference
Environment status chips were found in the suits of Poseidon 8's crew. They recorded the constituents of the atmosphere around the person wearing it. The Eleventh Doctor used one to determine Vortron radiation was causing sickness amongst the crew after expelling Vashta Nerada from the suits. (VG: Shadows of the Vashta Nerada)
