Piezoelectric vibrational energy harvester

Patent metadata

Field	Value
Publication number	US-9590533-B2
Application number	US-201414763149-A
Country	US
Kind code	B2
Filing date	Jan 23, 2014
Priority date	Jan 23, 2013
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

Abstract

A vibrational energy harvester having a base and a piezoelectric transducer formed from a layer of piezoelectric material and extending between a first end at the base and a second end. At least a portion of the piezoelectric transducer is arranged in a back and forth pattern between the first and second ends. A magnetic component provides a magnetic field within which at least a portion of the piezoelectric transducer operates so that it exhibits nonlinear behavior. A biomedical implantable device using the vibration energy harvester can extract energy from heartbeat waveforms (heartbeats) to thereby power a device within the body.

First claim

The invention claimed is:

1. A vibrational energy harvester, comprising:
a base; and
a piezoelectric transducer comprising a layer of piezoelectric material and extending between a first end at said base and a second end, wherein at least a portion of the piezoelectric transducer is configured to undergo mechanical strain in response to movement of the energy harvester and is arranged in a back and forth pattern between the first and second ends.

2. A vibrational energy harvester as defined in claim 1 , wherein the second end is a free end that moves with respect to the base in response to movement of the energy harvester.

3. A vibrational energy harvester as defined in claim 1 , wherein at least a portion of the layer of piezoelectric material is arranged in the back and forth pattern.

4. A vibrational energy harvester as defined in claim 1 , wherein the piezoelectric transducer is configured to have a characteristic force-deflection behavior in the absence of a magnetic field, the energy harvester further comprising a magnetic component having an associated magnetic field and being arranged so that a linear portion of said characteristic force-deflection behavior is rendered non-linear.

5. A vibrational energy harvester as defined in claim 1 , wherein the piezoelectric transducer has a unimorph zigzag geometry comprising a plurality of beams arranged parallel with one another with a gap defined between adjacent beams, each one of the beams being connected to an adjacent one of the beams by a connecting portion located at an end of each of the connected beams.

6. A vibrational energy harvester as defined in claim 1 , wherein the piezoelectric transducer comprises a bimorph beam.

7. A vibrational energy harvester as defined in claim 1 , wherein the energy harvester is a bi-stable energy harvester.

8. A vibrational energy harvester, comprising:
a base;
a piezoelectric transducer extending from the base; and
a magnetic component having an associated magnetic field, wherein at least a portion of the piezoelectric transducer operates within the magnetic field so that the transducer exhibits non-linear force-deflection behavior.

9. A vibrational energy harvester as defined in claim 8 , wherein the piezoelectric transducer comprises a cantilever beam extending from the base to a free end.

10. A vibrational energy harvester as defined in claim 8 , wherein the piezoelectric transducer comprises a bimorph beam.

11. A vibrational energy harvester as defined in claim 8 , wherein the energy harvester is a bi-stable energy harvester.

12. A vibrational energy harvester as defined in claim 8 , wherein the piezoelectric transducer comprises a beam and extends from the base to a free end that operates within the magnetic field.

13. A vibrational energy harvester as defined in claim 8 , wherein the piezoelectric transducer has a unimorph zigzag geometry comprising a plurality of beams arranged parallel with one another with a gap defined between adjacent beams, each one of the beams being connected to an adjacent one of the beams by a connecting portion located at an end of each of the connected beams.

14. A vibrational energy harvester as defined in claim 8 , wherein the piezoelectric transducer extends between a first end at said base and a second end and includes a layer of piezoelectric material, at least a portion of the piezoelectric transducer being arranged in a back and forth pattern between the first and second ends.

15. A method comprising the steps of:
providing a piezoelectric transducer having a geometry with an associated power output over a range of input frequencies; and
inducing non-linear force-deflection behavior in the piezoelectric transducer, thereby increasing the power output of the transducer over the range of input frequencies.

16. The method of claim 15 , wherein the step of inducing is performed by providing a magnetic force that acts on the transducer in such a way that the magnitude of the magnetic force varies with the amount of deflection of the transducer.

17. An implantable biomedical device, comprising a piezoelectric energy harvester having a piezoelectric transducer configured to exhibit non-linear force-deflection behavior.

18. An implantable biomedical device as defined in claim 17 , wherein the energy harvester is responsive to a heartbeat waveform.

19. An implantable biomedical device as defined in claim 18 , wherein the piezoelectric energy harvester is bi-stable and generates greater than 3 μW of power at all heart rates ranging from 7 beats per minute to 700 beats per minute.

20. A wireless monitoring device adapted for attachment to a structure to be monitored, the monitoring device being powered by a piezoelectric energy harvester configured to harvest vibrational energy from the structure and comprising a piezoelectric transducer having a layer of piezoelectric material, wherein:
at least a portion of the piezoelectric transducer is configured to undergo mechanical strain in response to movement of the energy harvester and is arranged in a back and forth pattern between first and second ends of the transducer;
the piezoelectric transducer exhibits non-linear behavior; or
at least a portion of the piezoelectric transducer is configured to undergo mechanical strain in response to movement of the energy harvester and is arranged in a back and forth pattern between first and second ends of the transducer, and the piezoelectric transducer exhibits non-linear force-deflection behavior.

Assignees

• Univ Michigan Regents

Inventors

• Inman Daniel J
• Karami M Amin
• Bradley David J

Classifications

• H02N2/186 Primary

  Vibration harvesters · CPC title

• H01L41/08

  Electricity · mapped topic

• H01L41/1136

  Electricity · mapped topic

• A61N1/3785

  generated by biological activity or substance, e.g. body movement · CPC title

• H10N35/00

  Magnetostrictive devices (integrated devices or assemblies of multiple devices H10N39/00) · CPC title