Multi-Layer Wireless Sensor Construct for Use at Electrically-Conductive Material Surfaces

• US 20150204709A1
• Filed: 10/22/2014
• Published: 07/23/2015
• Est. Priority Date: 10/24/2013
• Status: Active Grant

• Current Assignee: National Institute of Aerospace Asscoiates, United States of America as represented by the Administrator of NASA
• Original Assignee: U.S.A. as represented by the Administrator of the National Aeronautics and Space Administration
• Inventors: Dudley, Kenneth L., Szatkowski, George N., Smith, Laura J., Ticatch, Larry A., Nguyen, Truong X., Ely, Jay J., Koppen, Sandra V., Wang, Chuantong
• Granted Patent: US 10,180,341 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01F 23/26 by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
• CPC Class Codes: G01F 23/261 for discrete levels
• CPC Class Codes: G01R 33/1223 Measuring permeability, i.e. permeameters G01R33/14 takes precedence
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence

Abstract

A multi-layer wireless sensor construct is provided. The construct includes a first dielectric layer adapted to be attached to a portion of a first surface of an electrically-conductive material. A layer of mu metal is provided on the first dielectric layer. A second dielectric layer is provided on the layer of mu metal. An electrical conductor is provided on the second dielectric layer wherein the second dielectric layer separates the electrical conductor from the layer of mu metal. The electrical conductor has first and second ends and is shaped to form an unconnected open-circuit that, in the presence of a time-varying magnetic field, resonates to generate a harmonic magnetic field response having a frequency, amplitude and bandwidth.

Claims

1. A multi-layer wireless sensor construct for attachment to a first surface of an electrically-conductive material and for use in sensing presence of a liquid at a second surface of the electrically-conductive material, said wireless sensor construct comprising:

a first dielectric layer adapted to be attached to a portion of the first surface of the electrically-conductive material;

a layer of mu metal on said first dielectric layer wherein said first dielectric layer separates said layer of mu metal from the first surface of the electrically-conductive material;

a second dielectric layer on said layer of mu metal wherein said layer of mu metal separates said first dielectric layer from said second dielectric layer; and

an electrical conductor on said second dielectric layer wherein said second dielectric layer separates said electrical conductor from said layer of mu metal, said electrical conductor having first and second ends and shaped to form a spiral between said first and second ends, said first and second ends remaining electrically unconnected such that said electrical conductor so-shaped is maintained as an unconnected single-component open-circuit having inductance and capacitance wherein, in the presence of a time-varying magnetic field, said electrical conductor so-shaped resonates to generate a harmonic magnetic field response having a frequency, amplitude and bandwidth.

2. The multi-layer wireless sensor construct of claim 1, wherein said layer of mu metal comprises a solid sheet of mu metal.

3. The multilayer wireless sensor construct of claim 1, wherein said layer of mu metal has at least one hole defined therein.

4. A system for indicating a quantity of liquid in a container that is electrically conductive, comprising:

a plurality of wireless sensor constructs, each of said wireless sensor constructs including;

a first dielectric layer adapted to be attached to an exterior wall region of the container,

a layer of mu metal on said first dielectric layer wherein said first dielectric layer separates said layer of mu metal from the exterior wall region,

a second dielectric layer on said layer of mu metal wherein said layer of mu metal separates said first dielectric layer from said second dielectric layer, and

an electrical conductor on said second dielectric layer wherein said second dielectric layer separates said electrical conductor from said layer of mu metal, said electrical conductor having first and second ends and shaped to form a spiral between said first and second ends, said first and second ends remaining electrically unconnected such that said electrical conductor so-shaped is maintained as an unconnected single-component open-circuit having inductance and capacitance wherein, in the presence of a time-varying magnetic field, said electrical conductor so-shaped resonates to generate a harmonic magnetic field response having a frequency, amplitude and bandwidth;

a magnetic field response recorder having an antenna for wirelessly transmitting said time-varying magnetic field to said electrical conductor so-shaped and for wirelessly detecting said harmonic magnetic field response generated thereby, said magnetic field response recorder having an electrical impedance Z_SOURCE exclusive of electrical impedance of said antenna; and

a total electrical impedance Z_TOTAL being approximately matched to said electrical impedance Z_SOURCE said total electrical impedance Z_TOTAL defined by a parallel combination of said electrical impedance of said antenna, electrical impedance of said electrical conductor so-shaped, electrical impedance of said layer of mu metal, and electrical impedance of a portion of the container bounded by an outer periphery of said layer of mu metal.

5. The system of claim 4, wherein said layer of mu metal comprises a solid sheet of mu metal.

6. The system of claim 4, wherein said layer of mu metal has a least one hole defined therein.

7. The system of claim 4, wherein said container comprises a carbon fiber reinforced plastic.

8. A system for storing a liquid and for indicating a quantity of the liquid so-stored, comprising;

a container;

a plurality of wireless sensor constructs, each of said wireless sensor constructs attached to an exterior surface region of said container, each of said wireless sensor constructs including;

an electrical conductor having first and second ends and shaped to form a spiral between said first and second ends, said first and second ends remaining electrically unconnected such that said electrical conductor so-shaped is maintained as an unconnected single-component open-circuit having inductance and capacitance wherein, in the presence of a time-varying magnetic field, said electrical conductor so-shaped resonates to generate a harmonic magnetic field response having a frequency, amplitude and bandwidth, and

an electromagnetic window transparent to said harmonic magnetic field response, said electromagnetic window disposed between said electrical conductor so-shaped and an interior region of said container; and

a magnetic field response recorder having an antenna for wirelessly transmitting said time-varying magnetic field to said electrical conductor so-shaped and for wirelessly detecting said harmonic magnetic field response generated thereby, said magnetic field response recorder having an electrical impedance Z_SOURCE exclusive of electrical impedance of said antenna; and

a total electrical impedance Z_TOTAL being approximately matched to said electrical impedance Z_SOURCE , said total electrical impedance Z_TOTAL defined by a parallel combination. of said electrical impedance of said antenna, electrical impedance of said electrical conductor so-shaped, and electrical impedance of said electromagnetic window.

9. The system of claim 8, wherein said electromagnetic window comprises a portion of said container.

10. The system of claim 8, wherein said container is made from carbon fiber reinforced plastic, wherein said electromagnetic window includes a layer of mu metal coupled to said exterior surface region of said container and disposed between said electrical conductor son shaped and said exterior surface region of said container.

11. The system of claim 8, wherein said layer of mu metal comprises a solid sheet of mu metal.

12. The system of claim 8, wherein said layer of mu metal has a least one hole defined therein.