Acoustic sensor using curved piezoelectric film
View Patent ↗An acoustic sensor device comprising a substrate having a first surface and a second surface opposite the first surface, and an aperture formed therethrough, the second surface having a curved portion; a layer of piezoelectric film having a first surface disposed on the curved portion of the substrate second surface; and a layer of pliable material disposed on a second surface of the piezoelectric film opposite the first surface for contacting with an object to be sensed.
1. An acoustic sensor device comprising:
a substrate having a first surface and a second surface opposite the first surface, and an aperture formed therethrough, the second surface having a curved portion;
a layer of piezoelectric film having a first surface disposed on the curved portion of the substrate second surface; and
a layer of pliable material disposed on a second surface of the piezoelectric film opposite the first surface for contacting with an object to be sensed.
2. The device of claim 1 , further comprising a polymer layer disposed on a surface of the piezoelectric film.
3. The device of claim 1 , wherein the piezoelectric film comprises PVDF.
4. The device of claim 1 , wherein the substrate comprises a metal or plastic.
5. The device of claim 1 , wherein the pliable layer comprises a material having an acoustic impedance substantially close to an acoustic impedance of the object to be sensed.
6. The device of claim 1 , wherein the pliable layer comprises a rubber.
7. The device of claim 1 , wherein the pliable layer comprises a polyurethane.
8. The device of claim 2 , wherein the polymer layer is disposed between the piezoelectric film and the pliable layer.
9. An acoustic sensor device comprising:
a substrate having a first surface and a second surface opposite the first surface, and an aperture formed therethrough, the second surface having a curved portion;
a layer of piezoelectric film having a first surface disposed on the curved portion of the substrate second surface;
a layer of pliable material disposed on a second surface of the piezoelectric film opposite the first surface for contacting with an object to be sensed; and,
a housing having an opening through which a portion of said pliable material protrudes for contacting with an object to be sensed.
10. The device of claim 9 , wherein the housing pressure clamps the first surface of the piezoelectric film to at least a non-curved portion of the substrate.
11. An acoustic sensor device comprising:
a substrate having a first surface and a second surface opposite the first surface, and an aperture formed therethrough, the second surface having a curved portion;
a layer of piezoelectric film having a first surface disposed on the curved portion of the substrate second surface;
a layer of pliable material disposed on a second surface of the piezoelectric film opposite the first surface; and
a housing for holding the substrate, piezoelectric film and pliable material, said housing having an opening through which a portion of said pliable material protrudes for contacting with an object to be sensed.
12. An acoustic sensor device comprising:
a substrate having a first surface and a second surface opposite the first surface, and an aperture formed therethrough, the second surface having a curved portion;
a layer of piezoelectric film having a first surface disposed on the curved portion of the substrate second surface;
a layer of pliable material disposed on a second surface of the piezoelectric film opposite the first surface; and,
a housing for holding the substrate, piezoelectric film and pliable material, said housing having an opening through which a portion of said pliable material protrudes for contacting with an object to be sensed;
wherein the housing pressure clamps the first surface of the piezoelectric film to at least a non-curved portion of the substrate.
13. The device of claim 11 , wherein the piezoelectric film comprises PVDF.
14. The device of claim 13 , wherein the PVDF film has a thickness of 28-110 microns.
15. The device of claim 11 , wherein the pliable layer comprises a rubber.
16. The device of claim 11 , wherein the pliable layer comprises a polyurethane.
17. An acoustic sensor device comprising:
a substrate having a first surface and a second surface opposite the first surface, and an aperture formed therethrough, the second surface having a curved portion;
a layer of piezoelectric film having a first surface disposed on the curved portion of the substrate second surface;
a layer of pliable material disposed on a second surface of the piezoelectric film opposite the first surface for contacting with an object to be sensed; and
a polymer layer disposed on a surface of the piezoelectric film, for shielding of the piezoelectric film from electrical noise.
18. The device of claim 17 , wherein the polymer layer is disposed between the piezoelectric film and the pliable layer.
19. The device of claim 17 , wherein a grounded electrode is coupled to the first surface of the piezoelectric film.
20. A method of sensing an acoustic signal comprising:
forming an acoustic sensor device comprising a substrate having a first surface and a second surface opposite the first surface and an aperture formed therethrough, and also comprising a layer of piezoelectric film having a first surface and a second surface opposite the first surface, the first surface being disposed on a curved portion of the substrate second surface and the second surface being disposed on a layer of pliable material;
contacting said layer of pliable material with an object to be sensed;
causing, through transmission of the sensed acoustic signal, an application of pressure on the piezoelectric film in a direction substantially normal to a surface of the film; and
generating, through the piezoelectric effect of the film, an electrical signal indicative of said acoustic signal.