A respiratory effort belt to be worn by a person undergoing a sleep study comprises a PVDF piezo film transducer having opposite major surfaces metalized and electrical leads electronically connected to the metalized surfaces adhesively bonded to an inelastic cover layer that is, in turn, adhesively joined to an stretchable elastic band that functions as a belt to be secured to the person's chest or abdomen. The transducer produces a time-varying output voltage waveform due to rubbing contact between the elastic band and the PVDF film and not due to tensile forces acting on the film as the person's chest or abdomen rises and falls with inspiration and expiration.
