Abstract: An apparatus for accurately indicating respiration movements on a recorder. The apparatus comprises two piezoelectric transducers which are disposed parallel to each other and each mounted on a support member. Between the two transducers is an elastic belt forming an elastic band, a portion of the belt having a loop or wave shape. The entire apparatus is enclosed in a rigid housing, and the elastic band wraps around the patient. When horizontal stretching forces are applied to the band, i.e. during respiration, the loop shape of the belt causes both piezoelectric transducers to bend in the same direction and generate an electronic signal for recording. Any other external force will cause the two transducers to bend in opposite directions, thereby canceling each other, and generating no signal for recording. The apparatus may further be used for prolonged periods of time and is also very sensitive, thereby resulting in accurate respiration data.