transducer

Concise Oxford English Dictionary © 2008 Oxford University Press:
transducer /tranzˈdjuːsə, trɑːnz-, -ns-/

▶noun a device that converts variations in a physical quantity, such as pressure or brightness, into an electrical signal, or vice versa.

– derivatives
transduce verb,
transduction noun.

– origin 1920s: from L. transducere ‘lead across’ + -er1.