Magnetic field sensing systems and methods

Patent metadata

Field	Value
Publication number	US-10816614-B2
Application number	US-201716077497-A
Country	US
Kind code	B2
Filing date	Feb 14, 2017
Priority date	Feb 14, 2016
Publication date	Oct 27, 2020
Grant date	Oct 27, 2020

Abstract

A magnetic field sensor system comprises an electrically conducting film of ferromagnetic nanoparticles printed directly on a supporting structure, and electrically conducting contacts coupled to the film for injecting an electric current into the film and measuring a voltage generated across said film responsive to said injected current in a direction that is generally perpendicular to the current direction in the plane of the film.

First claim

What is claimed is:

1. A magnetic field sensor system, comprising:
an electrically conducting film of ferromagnetic nanoparticles, and
electrically conducting contacts coupled to said film for injecting an electric current into the film;
wherein the electrically conducting contacts are coupled to said film so as to allow measuring a voltage through a subset of the electrically conducting contacts, the voltage being generated across said film responsive to said injected current,
wherein the electrically conducting film comprises individual ferromagnetic nanoparticles coated with a polymeric or molecular surfactant layer, wherein each of the ferromagnetic nanoparticles is formed of a single crystal having a diameter of 3 to 30 nm; and
the electrically conducting film is sensitive to the Extraordinary Hall Effect.

2. A method of sensing, comprising injecting an electrical current via the electrically conducting contacts of the system of claim 1 , and measuring a voltage generated across said film responsively to said injected current.

3. A switching system, comprising the magnetic field sensor system of claim 1 .

4. A motion sensing system, comprising the magnetic field sensor system of claim 1 .

5. A rotation sensing system, comprising the magnetic field sensor system of claim 1 .

6. A printed circuit board, comprising the magnetic field sensor system of claim 1 .

7. The system according to claim 1 , wherein said ferromagnetic nanoparticles are printed directly on a supporting structure to form an aggregate of said ferromagnetic nanoparticles on said supporting structure.

8. The system according to claim 1 , wherein said film has measurable magnetic field sensitivity when a magnetic field of about 0.1 mT is applied.

9. The system according to claim 1 , wherein said electrically conducting contacts are printed.

10. The system according to claim 1 , wherein the resistivity of said film is at least 2 times larger than a characteristic bulk resistivity of a ferromagnetic material forming said nanop articles.

11. The system according to claim 1 , wherein a roughness of said film is smaller or of the same order of magnitude as a thickness of said film.

12. The system according to claim 11 , wherein a thickness of said film is at least 10 nm.

13. The system according to claim 1 , wherein said ferromagnetic material comprises at least one substance selected from the group consisting of nickel, cobalt and iron.

14. The system according to claim 1 , wherein said film has magnetic field sensitivity of at least 2m′Ω/T when a magnetic field up to a saturation point is applied.

15. The system according to claim 1 , wherein an Extraordinary Hall Effect resistance of the film at a saturating magnetic field, measured using currents in the range of from about 1 mA to about 10 mA, is between about 1 to about 10 mΩ.

16. The system according to claim 1 , wherein an Extraordinary Hall Effect resistance of the film decreases by no more than approximately 10% when the film is cooled from 300 K to 77 K.

17. A method of fabricating a magnetic field sensor, comprising:
forming individual ferromagnetic nanoparticles coated with a polymeric or molecular surfactant layer, wherein each of the ferromagnetic nanoparticles is formed of a single crystal having a diameter of 3 to 30 nm;
printing a film of said individual ferromagnetic nanoparticles directly on a supporting structure, and
coupling electrically conducting contacts to said film so as to allow for injecting an electric current into the film and measuring a voltage generated across said film responsive to said injected current due to the Extraordinary Hall Effect.

18. The method as defined in claim 17 , wherein:
the forming step comprises forming a dispersion of the ferromagnetic nanoparticles in ethylene glycol; and
the printing step comprises depositing the dispersion onto the supporting structure, and drying the deposited dispersion under vacuum and with application of heat of about 100C, to thereby produce a conducting film.

19. The method as defined in claim 17 , wherein the ferromagnetic particles are formed from ferromagnetic material comprising at least one substance selected from a group consisting of nickel, cobalt, and iron, and the forming step comprises reducing the ferromagnetic material from a cationic state to a neutral state.

Assignees

• Univ Ramot

Inventors

• Gerber Alexander
• Markovich Gil
• Ben Gur Leah
• Tirosh Einat

Classifications

• G01R33/093

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title

• B82Y25/00

  Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance · CPC title

• G01R33/07 Primary

  Hall effect devices · CPC title

• H01L43/06

  Electricity · mapped topic

• H10N52/00

  Hall-effect devices (integrated devices or assemblies of multiple devices H10N59/00) · CPC title