Respiratory effort belt
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.
1. A respiratory effort belt comprising:
(a) an elastic band of a length sufficient to encircle a person's torso;
(b) a transducer comprising a strip of PVDF film having a layer of metallization on opposed major surfaces of the strip;
(c) first and second electrical leads individually connected to the layers of metallization; and
(d) an inelastic cover layer adhesively bonded to the transducer and having a greater area than that of the PVDF film, the cover layer being adhesively bonded onto the elastic band whereby an electrical output on said leads results primarily from rubbing contact between the elastic band and the PVDF film as the elastic band is stretched and contracts and not from tensile stress acting on the PVDF film.
2. The respiratory effort belt of claim 1 wherein the inelastic cover layer is a paper exhibiting a non-stretch characteristic when subjected to tensile forces transmitted to the cover layer from stretching of the elastic band.
3. The respiratory effort belt of claim 2 wherein the cover layer is a paper face-stock material.
4. The respiratory effort belt of claim 1 wherein the adhesive bonding the transducer cover layer is a hot melt rubber based adhesive.
5. The respiratory effort belt of claim 4 wherein the adhesive bonding the cover layer to the elastic band is a hot melt rubber based adhesive.