Microelectromechanical device and system with low-impedance resistive transducer

Patent metadata

Field	Value
Publication number	US-9815686-B2
Application number	US-201615293147-A
Country	US
Kind code	B2
Filing date	Oct 13, 2016
Priority date	Oct 23, 2015
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

A microelectromechanical device comprising a mechanical structure extending along a longitudinal direction, linked to a planar substrate by an anchorage situated at one of its ends and able to flex in a plane parallel to the substrate, the mechanical structure comprises a joining portion, which links it to each anchorage and includes a resistive region exhibiting a first and second zone for injecting an electric current to form a resistive transducer, the resistive region extending in the longitudinal direction from an anchorage and arranged so a flexion of the mechanical structure in the plane parallel to the substrate induces a non-zero average strain in the resistive region and vice versa; wherein: the first injection zone is carried by the anchorage; and the second injection zone is carried by a conducting element not fixed to the substrate and extending in a direction, termed lateral, substantially perpendicular to the longitudinal direction.

First claim

The invention claimed is:

1. A microelectromechanical device comprising a mechanical structure extending mainly along a longitudinal direction and linked to a planar substrate by at least one anchorage situated at one of its ends along the longitudinal direction and able to flex in a plane parallel to the substrate, the mechanical structure comprising a joining portion which links the mechanical structure to the said at least one anchorage and which includes a resistive region exhibiting a first injection zone and a second infection zone for injecting an electric current so as to form a resistive transducer, the resistive region extending mainly in the longitudinal direction from said at least one anchorage and being arranged in such a way that a flexion of the mechanical structure in the plane parallel to the substrate induces a non-zero average strain in the resistive region and vice versa;
wherein the first injection zone is carried by the at least one anchorage; and
wherein the second injection zone is carried by a first conducting element not fixed to the substrate and extending in a lateral direction substantially perpendicular to the longitudinal direction;
the substrate being parallel to a plane defined by the longitudinal direction and the lateral direction.

2. The microelectromechanical device according to claim 1 , wherein the resistive region also exhibits at least one third infection zone for injecting an electric current carried by a second conducting element not fixed to the substrate, extending in the lateral direction and distinct from the first conducting element carrying the second injection zone, the second injection zone being arranged between the first injection zone and the third injection zone.

3. The microelectromechanical device according to claim 1 , wherein the mechanical structure is made of semi-conducting material and the first and second injection zones comprise metallic layers deposited above respective portions of said semi-conducting material and forming ohmic contacts.

4. The microelectromechanical device according to claim 1 , wherein at least one of the first injection zone and second injection zone extends over the entire width of the joining portion, beyond the extent of the resistive region.

5. The microelectromechanical device according to claim 1 , wherein at least the second injection zone is linked to a contact pad fastened to the substrate by a beam-shaped element not fixed to the substrate and exhibiting a flexibility in the lateral direction.

6. The microelectromechanical device according to claim 5 , wherein the beam-shaped element exhibits a flexibility in the lateral direction that is greater than that of the mechanical structure.

7. The microelectromechanical device according to claim 1 , wherein the joining portion of the mechanical structure comprises at least two parallel beams, oriented along the longitudinal direction and disposed on either side of a neutral fibre of the joining portion, the resistive region being included in one of the beams.

8. The microelectromechanical device according to claim 1 , wherein the joining portion of the mechanical structure comprises a single beam oriented along the longitudinal direction, the resistive region being arranged on a side of the beam, the remainder of the beam being made of material exhibiting a higher electrical resistivity.

9. The microelectromechanical device according to claim 1 , further comprising an electrical detection circuit, configured to measure a time-varying electrical resistance of the resistive region between the first injection zone and second injection zone.

10. The microelectromechanical device according to claim 1 , further comprising an electrical actuation circuit, configured to inject an alternating electrical signal into the resistive region by way of the first injection zone and second injection zone.

11. The microelectromechanical device according to claim 1 , wherein the mechanical structure comprises two resistive regions included in the joining portion and arranged in such a way that a flexion of the joining portion in a plane parallel to the substrate induces non-zero average strains of opposite sign in the resistive regions, each resistive region exhibiting a first zone and a second zone for injecting an electric current, the first zone for injecting an electric current being disjoint.

12. The microelectromechanical device according to claim 11 , further comprising an electrical detection circuit, configured to measure a difference, varying over time, between resistances of the first zone and second zone for injecting an electric current.

13. The microelectromechanical device according to claim 11 , further comprising an electrical actuation circuit configured to inject alternating electrical signals at an actuation frequency and in phase opposition, superimposed on a direct electrical signal or at a different frequency from the actuation frequency, into the two resistive regions by way of the first zone and second zone for injecting an electric current of said two resistive regions.

14. The microelectromechanical device according to claim 11 , further comprising an electrical actuation circuit configured to inject alternating electrical signals at an actuation frequency, and in phase quadrature, without superposition with a direct electrical signal or at a different frequency from the said actuation frequency, into said two resistive regions by way of the first zone and second zone for injecting an electric current of said two resistive regions.

15. The microelectromechanical system comprising a first microelectromechanical device according to claim 1 which further comprises an electrical detection circuit, configured to measure a time-varying electrical resistance of the resistive region between the the first injection zone and the second injection zone, and a second microelectromechanical device according to claim 1 which further comprises an electrical actuation circuit, configured to inject an alternating electrical signal into the resistive region by way of the the first injection zone and the second injection zone, wherein the mechanical structures of the first and of the second device are mechanically coupled, the actuation circuit of the first device is configured to inject an alternating electrical signal at an actuation frequency, superimposed on a direct electrical signal or at a different frequency from the actuation frequency, and the detection circuit of the second device is configured to measure a variation in resistance at the actuation frequency.

16. The microelectromechanical system comprising a first microelectromechanical device according to claim 11 which further comprises an electrical actuation circuit configured to inject alternating electrical signals at an actuation frequency, and in phase quadrature, without superposition with a direct electrical signal or at a different frequency from the said actuation frequency, into said two resistive regions by way of the first zone and second zone for injecting an electric current of said two resistive regions, and a second microelectromechanical device according to claim 11 which further comprises an electrical detection circuit, configured to measure a difference, varying over time, between resistances of the first zone and second zone for injecting an electric current, wherein the mechanical structures of the first and of the second device are mechanically coupled, the actuation circuit of the first device is configured to inject an alternating electric current at a first frequency and the detection circuit of

Assignees

• Vmicro
• Centre Nat Rech Scient

Inventors

• Walter Benjamin
• Faucher Marc

Classifications

• B81B2201/031

  Thermal actuators · CPC title

• B81B2201/02

  Sensors · CPC title

• B81B3/0045 Primary

  Improve properties related to angular swinging, e.g. control resonance frequency · CPC title

• B81B2203/0118

  Cantilevers · CPC title

• B81B3/0086 Primary

  Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage · CPC title