The invention relates to an ultrasonic transducer which is used to form an image of a human or animal organ and which can also be used to measure the elasticity of said organ. The inventive transducer comprises: at least one mobile part (3) which is arranged to induce the propagation of a low-frequency vibration in the direction of the organ when said mobile part (3) is actuated, such as to deliver an impact against the human or animal body and at least one fixed part (4). The invention also relates to an imaging system comprising one such transducer (2).
