Piezoelectric transducer for an energy-harvesting system

Patent metadata

Field	Value
Publication number	US-2018198383-A1
Application number	US-201815913590-A
Country	US
Kind code	A1
Filing date	Mar 6, 2018
Priority date	Jul 31, 2013
Publication date	Jul 12, 2018
Grant date	—

Abstract

A piezoelectric transducer for energy-harvesting systems includes a substrate, a piezoelectric cantilever element, a first magnetic element, and a second magnetic element, mobile with respect to the first magnetic element. The first magnetic element is coupled to the piezoelectric cantilever element. The first magnetic element and the second magnetic element are set in such a way that, in response to relative movements between the first magnetic element and the second magnetic element through an interval of relative positions, the first magnetic element and the second magnetic element approach one another without coming into direct contact, and the interaction between the first magnetic element and the second magnetic element determines application of a force pulse on the piezoelectric cantilever element.

First claim

1 . A system, comprising:
a piezoelectric transducer configured to harvest environmental energy and to convert harvested environmental energy into a harvesting electrical signal, the piezoelectric transducer including:
a semiconductor substrate;
a cantilever component having a piezoelectric element;
a first magnetic element on the cantilever component; and
a second magnetic element configured to interact with the first magnetic element to move the cantilever component;
a storage element configured to store electrical energy from the piezoelectric transducer; and a harvesting interface coupled to the piezoelectric transducer and configured to provide a charge electrical signal to the storage element as a function of the harvesting electrical signal.

2 . The system of claim 1 , further comprising:
a movable mass elastically coupled to the substrate, the second magnetic element being on the movable mass and the cantilever component extending from a portion of the substrate.

3 . The system of claim 1 , further comprising a driving element configured to receive the harvesting electrical signal and to control a switch.

4 . The system of claim 3 wherein the driving element is configured to selectively connect and disconnect the harvesting interface to the storage element based on the piezoelectric transducer.

5 . The system of claim 4 wherein the driving element is configured to connect the harvesting interface to the storage element when the harvesting electrical signal exceeds an activation threshold to charge the storage element.

6 . A device, comprising:
a substrate including a recess having a base and a sidewall, the base extending in a first direction, the sidewall extending in a second direction that is transverse to the first direction; a moveable mass coupled to the base, the movable mass configured move in the first direction; a plurality of cantilever piezoelectric elements extending from the sidewall towards the moveable mass; a plurality of first magnetic elements on the plurality of cantilever piezoelectric elements, respectively; and a plurality of second magnetic elements on the moveable mass.

7 . The device of claim 6 wherein the plurality second magnetic elements are configured to respectively interact with the plurality of first magnetic elements, and respectively generate respective force pulses on the plurality of cantilever piezoelectric elements, respectively.

8 . The device of claim 6 wherein the plurality of cantilever piezoelectric elements extend towards the movable mass without directly contacting the movable mass.

9 . The device of claim 6 wherein the movable mass has a circular shape, and the plurality of cantilever piezoelectric elements extends in a radial direction.

10 . The device of claim 6 wherein the movable mass configured to rotate in the first direction.

11 . The device of claim 6 , further comprising:
an anchorage coupled to the base; and a suspension coupling the movable mass to the anchorage.

12 . The device of claim 6 , further comprising:
a cap on the substrate and overlying the moveable mass.

13 . A device, comprising:
a substrate including a surface; a moveable mass coupled to the surface of the substrate, the moveable mass configured to move in a first direction; a cantilever piezoelectric element coupled to the moveable mass, the cantilever piezoelectric element extending in a second direction that is transverse to the first direction; and a first magnetic element on the cantilever piezoelectric element; and a second magnetic element on the surface of the substrate, the first magnetic element being positioned on the cantilever piezoelectric element such that the first magnetic element overlies the second magnetic element when the moveable mass moves in the first direction.

14 . The device of claim 13 , further comprising:
an anchorage coupled to the surface of the substrate; and a suspension coupling the movable mass to the anchorage.

15 . The device of claim 14 , further comprising:
a contact pad on the surface of the substrate, the contact pad being electrically coupled to the cantilever piezoelectric element via the anchorage and the suspension.

16 . The device of claim 13 wherein the cantilever piezoelectric element includes a supporting plate and a piezoelectric layer, and the piezoelectric layer is between the supporting plate and the first magnetic element.

17 . The device of claim 16 wherein the piezoelectric layer is spaced from the supporting plate by the first magnetic element in the first direction.

Assignees

• St Microelectronics Srl

Inventors

• Procopio Francesco
• Valzasina Carlo
• Corigliano Alberto
• Ardito Raffaele
• Gafforelli Giacomo

Classifications

• H02N2/188 Primary

  adapted for resonant operation · CPC title

• H02N2/186 Primary

  Vibration harvesters · CPC title

• H02N2/181

  Circuits; Control arrangements or methods · CPC title