PBLG based planar microphones

Patent metadata

Field	Value
Publication number	US-9838800-B2
Application number	US-201514603992-A
Country	US
Kind code	B2
Filing date	Jan 23, 2015
Priority date	Jan 24, 2014
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

A piezoelectric, poly (γ-benzyl-α,L-glutamate) (“PBLG”) planar microphone, and method for construction thereof, are disclosed. The microphone includes at least a polyester film, a piezoelectric, hot pressed poly (γ-benzyl-α,L-glutamate) (“HPPBLG”) layer, and an aluminum coating for the HPPBLG layer. The coated HPPBLG layer is coupled to the polyester film.

First claim

What is claimed:

1. A planar microphone comprising:
a cylindrical chamber;
a polyester film;
a first piezoelectric, hot pressed poly (γ-benzyl-α,L-glutamate) (“HPPBLG”) layer;
an aluminum coating for the first HPPBLG layer;
a second piezoelectric, HPPBLG layer; and
an aluminum coating for the second HPPBLG layer, wherein
top and bottom surfaces of the first HPPBLG layer and the second HPPBLG layer, respectively, are coated with aluminum,
the aluminum-coated first HPPBLG layer and the aluminum-coated second HPPBLG layer are adhered to opposite sides of the polyester film, and
the aluminum-coated first HPPBLG layer, the aluminum-coated second HPPBLG layer, and the polyester film are mounted within the cylindrical chamber.

2. The microphone of claim 1 , wherein the polyester film comprises biaxially-oriented polyethylene terephthalate (BoPET).

3. The microphone of claim 1 , wherein the polyester film has a thickness of approximately 25 μm.

4. The microphone of claim 1 , wherein the first HPPBLG layer or the second HPPBLG layer is cut at an angle of approximately 45° relative to a direction of fiber in the first HPPBLG layer or the second HPPBLG layer.

5. The microphone of claim 1 , wherein the first HPPBLG layer or the second HPPBLG layer comprises two or more coupled HPPBLG films.

6. The microphone of claim 5 , wherein the HPPBLG films are coupled using a low viscosity epoxy.

7. The microphone of claim 1 , wherein the aluminum-coated first HPPBLG layer or the aluminum-coated second HPPBLG layer is coupled to the polyester film using an adhesive.

8. The microphone of claim 1 , wherein the first HPPBLG layer or the second HPPBLG layer has a d14 piezoelectric coefficient d 14 of approximately −1 pC/N.

9. A method of manufacturing a planar microphone comprising:
fabricating a film of first poly (γ-benzyl-α,L-glutamate) (“PBLG”) fibers, wherein the PBLG fibers are directionally aligned;
applying a hot press to the film of first PBLG fibers;
cutting the hot pressed film of first PBLG fibers at approximately 45° relative to the directional alignment of the first PBLG fibers;
coating the cut film of first PBLG fibers with aluminum;
adhering the aluminum coated film of first PBLG fibers to a polyester film;
fabricating a film of second poly (γ-benzyl-α,L-glutamate) (“PBLG”) fibers, wherein the PBLG fibers are directionally aligned;
applying the hot press to the film of second PBLG fibers;
cutting the hot pressed film of second PBLG fibers at approximately 45° relative to the directional alignment of the second PBLG fibers;
coating the cut film of second PBLG fibers with aluminum;
adhering the aluminum-coated film of second PBLG fiber to the polyester film; and
mounting the aluminum-coated film of first PBLG fibers, the aluminum-coated film of second PBLG fibers, and the polyester film within the cylindrical chamber, wherein
top and bottom surfaces of the cut film of first PBLG fibers and the cut film of second PBLG fibers, respectively, are coated with aluminum, and
the aluminum-coated film of first PBLG fiber and the aluminum-coated film of second PBLG fibers are adhered to opposite sides of the polyester film.

10. The method of claim 9 , wherein applying the hot press to the first or second film of PBLG fibers comprises:
applying a stress of approximately 1,000 pounds for approximately 30 minutes at approximately 100° C.

11. The method of claim 9 , wherein fabricating the first or second film of PBLG fibers comprises:
loading a syringe with a PBLG solution;
applying a voltage between a tip of the syringe and a grounded, rotating mandrel wrapped with an aluminum fool target;
peeling the first or second film of PBLG fibers from the aluminum foil target.

12. The method as in claim 11 , wherein the mandrel is rotated at approximately 2,500 rotations per minute when the voltage is applied.

13. The method as in claim 11 , wherein the voltage is approximately −12 kV.

14. The method as in claim 11 , wherein the distance between the syringe and the mandrel is approximately 5 cm.

15. The method as in claim 11 , wherein the syringe has a flow rate of approximately 2 mL/hr.

16. The method as in claim 9 , wherein the polyester film comprises a biaxially-oriented polyethylene terephthalate (“BoPET”) film.

17. The method as in claim 16 , wherein the BoPET film has a thickness of approximately 25 μm.

18. The method as in claim 17 , wherein the aluminum coated film of first PBLG fibers or the aluminum-coated film of second PBLG fibers is adhered to the BoPET film using a low viscosity epoxy.

19. The method as in claim 9 , wherein the cylindrical chamber is approximately 2.45 cm in diameter and 1.7 cm in height.

20. The method as in claim 9 , wherein the cylindrical chamber comprises an open backside.

21. The method as in claim 9 , wherein the cylindrical chamber comprises a sealed backside.

22. A sensor comprising:
a cylindrical chamber;
a first aluminum coated, piezoelectric poly (γ-benzyl-α,L-glutamate) (“PBLG”) layer mounted within the cylindrical chamber; and
a second aluminum-coated, piezoelectric PBLG layer mounted within the cylindrical chamber, wherein
top and bottom surfaces of the first aluminum-coated PBLG layer and the second aluminum-coated PBLG layer, respectively, are coated with aluminum, and
the first aluminum-coated PBLG layer and the second aluminum-coated PBLG layer are adhered to opposite sides of a polyester film.

23. The sensor of claim 22 , wherein the cylindrical chamber comprises an open backside.

24. The sensor of claim 23 , wherein the cylindrical chamber comprise a sealed backside.

25. The sensor of claim 22 , wherein the first or second PBLG layer has a d 14 piezoelectric coefficient d14 of approximately −1 pC/N.

26. The sensor of claim 22 , wherein the first or second PBLG layer comprises two hot pressed PBLG (“HPPBLG”) layers.

27. The sensor of claim 26 , wherein the two HPPBLG layers are connected in series.

28. The sensor of claim 26 , wherein the two HPPBLG layers are connected in parallel.

29. The sensor of claim 26 , wherein one of the HPPBLG layers is oriented approximately ninety degrees relative to the other HPPBLG layer.

30. A method of manufacturing a planar microphone comprising:
fabricating first and second films of poly (γ-benzyl-α,L-glutamate) (“PBLG”) fibers, wherein the PBLG fibers are directionally aligned;
applying a hot press to the first and second films of PBLG fibers to form first and second hot pressed PBLG (“HPPBLG”) films;
orienting the first HPPBLG film at approximately ninety degrees relative to of the second HPPBLG film;
coating top and bottom surfaces of the first and second HPPBLG films, respectively, with aluminum;
adhering a polyester film to the aluminum-coated first and second HPPBLG films, wherein the aluminum-coated first HPPBLG film and the aluminum-coated second HPPBLG film are adhered to opposite sides of the polyester film; and
mounting the aluminum-coated first and second HPPBLG films and the polyester film within a cylindrical chamber.

Assignees

• Univ Johns Hopkins
• The Johns Hopkins Univeristy

Inventors

• West James E
• Ren Kailiang
• Yu Michael

Classifications

• H01L41/00

  Electricity · mapped topic

• H04R17/025 Primary

  using a piezoelectric polymer · CPC title

• H04R1/44

  Special adaptations for subaqueous use, e.g. for hydrophone · CPC title