Abstract: A wind turbine rotor blade is provided including a reinforcement element embedded in the body of the rotor blade and extending in a longitudinal direction of the rotor blade; a number of piezo-electric transducers arranged between the leading edge of the rotor blade and the reinforcement element; a number of piezo-electric transducers arranged between the reinforcement element and the trailing edge of the rotor blade; and a connector arrangement configured to apply an excitation signal to any one of the piezo-electric transducers, and to transmit a sensed signal from any one of the piezo-electric transducers to an evaluation module. A wind turbine including a number of such rotor blades and a method of measuring strain in a reinforcement element arranged in such a rotor blade is also provided.