PZT MEMS resonant Lorentz force magnetometer

• US 7,642,692 B1
• Filed: 09/15/2005
• Issued: 01/05/2010
• Est. Priority Date: 09/15/2005
• Status: Expired due to Fees

• Current Assignee: United States Secretary of the Army
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Pulskamp, Jeffrey S.
• Primary Examiner(s): Benson; Walter
• Assistant Examiner(s): Addison; Karen B
• Application Number:
  US11/226,377
• Time in Patent Office: 1,573 Days
• Field of Search: 310/309, 310/338, 310/316.01, 324/260, 324/244, 324/259, 735/90, 736/49, 736/62
• US Class Current: 310/309
• CPC Class Codes: G01R 33/028 Electrodynamic magnetometers
• CPC Class Codes: G01R 33/0286 comprising microelectromechanical systems [MEMS] MEMS devices in general B81B
• CPC Class Codes: H10N 30/302 Sensors

Abstract

A MEMS magnetometer comprises a deflectable resonator comprising a base layer; a Lorentz force (LF) drive conductor attached to the base layer; and a piezoelectric sensor attached to the base layer and electrically isolated from the LF drive conductor. The LF drive conductor comprises conductive material configured for receiving a current at a mechanical resonant frequency of the device capable of causing mechanical deformation of the deflectable resonator, wherein the current causes formation of Lorentz forces in a presence of a magnetic field, and wherein the deflectable resonator is mechanically deformed as a result of the formation of the Lorentz forces. The mechanical deformation of the deflectable resonator generates a detectable piezoelectric electrical signal that is proportional to the magnitude of the magnetic field.

Claims

1. A configurable microelectromechanical system (MEMS) magnetometer comprising a deflectable resonator comprising:

a base layer;

a Lorentz force (LF) drive conductor attached to said base layer; and

a piezoelectric sensor attached to said base layer and electrically isolated from said LF drive conductor wherein said MEMS system is capable of processing maximum drive current equivalent to the maximum current of the Lorentz force drive conductor.

2. The MEMS magnetometer of claim 1, wherein said deflectable resonator comprises a torsional loop configuration.

3. The MEMS magnetometer of claim 1, wherein said LF drive conductor comprises conductive material configured for receiving a current at a resonant frequency capable of causing mechanical deformation of said deflectable resonator at one or more of a plurality of resonant frequencies.

4. The MEMS magnetometer of claim 3, wherein said current causes formation of Lorentz forces in a presence of a magnetic field.

5. The MEMS magnetometer of claim 4, wherein said deflectable resonator is mechanically deformed as a result of the formation of said Lorentz forces.

6. The MEMS magnetometer of claim 1, wherein said piezoelectric sensor comprises:

a bottom electrode;

a piezoelectric layer over and adjacent to said bottom electrode;

a top electrode over and adjacent to said piezoelectric layer; and

an isolator electrically isolating said bottom electrode from said top electrode.

7. The MEMS magnetometer of claim 1, further comprising:

a first interconnect structure connected to said LF drive conductor; and

a second interconnect structure connected to said piezoelectric sensor, wherein said second interconnect structure is electrically isolated from said first interconnect structure.

8. The MEMS magnetometer of claim 1, wherein said electrical isolation further comprises a silicon dioxide isolator.

9. A method for detecting a magnetic field using a magnetometer comprising a deflectable resonator comprising a base layer;

a Lorentz force (LF) drive conductor attached to said base layer; and

a piezoelectric sensor attached to said base layer and electrically isolated from said LF drive conductor, said method comprising;

placing said magnetometer in a magnetic field;

applying an AC current corresponding to a mechanical resonant frequency of the resonator to said LF drive conductor; and

detecting a mechanical deformation of said deflectable resonator with a piezoelectrically generated signal,

wherein an amount of deformation of said deflectable resonator is proportional to a piezoelectric signal generated by said piezoelectric sensor, and wherein said piezoelectric signal is proportional to a magnitude of said magnetic field.

10. The method of claim 9, wherein said deflectable resonator comprises a torsional loop configuration.

11. The method of claim 9, wherein said LF drive conductor comprises conductive material configured for receiving said current at a resonant frequency capable of causing said mechanical deformation of said deflectable resonator.

12. The method of claim 11, wherein application of said current causes formation of Lorentz forces.

13. The method of claim 12, wherein said deflectable resonator is mechanically deformed as a result of the formation of said Lorentz forces, and wherein said piezoelectric sensor detects said mechanical deformation.

14. The method of claim 9, wherein said piezoelectric sensor comprises:

a bottom electrode;

a piezoelectric layer over and adjacent to said bottom electrode;

a top electrode over and adjacent to said piezoelectric layer; and

an isolator electrically isolating said bottom electrode from said top electrode.

15. The method of claim 9, wherein said magnetometer further comprises:

a first interconnect structure connected to said LF drive conductor; and

a second interconnect structure connected to said piezoelectric sensor, wherein said second interconnect structure is electrically isolated from said first interconnect structure.

16. The method of claim 9, further comprising forming said isolator from silicon dioxide.