EMBEDDABLE MOISTURE SENSOR, MEASUREMENT DEVICE AND METHOD OF USE THEREOF

• US 20100090713A1
• Filed: 10/14/2009
• Published: 04/15/2010
• Est. Priority Date: 10/14/2008
• Status: Active Grant

• Current Assignee: Donald J. Geisel
• Original Assignee: Donald J. Geisel
• Inventors: Geisel, Donald J.
• Granted Patent: US 8,542,025 B2
• Time in Patent Office: Days
• US Class Current: 324/668
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01N 33/383 Concrete or cement
• CPC Class Codes: G01N 33/42 Road-making materials G01N33/38 takes precedence

Abstract

Disclosed herein is a method of interrogating a resonant circuit that includes embedding a resonant circuit into a material, wherein a dielectric of a capacitor of the resonant circuit is the material. The method includes remotely determining the resonant frequency of the electrical circuit with a measurement device, wherein the determining is accomplished automatically. Finally, the method includes remotely automatically determining at least one of an estimated or precise resistance of the resonant circuit, an estimated or precise quality factor of the resonant circuit, and an estimated or precise voltage ratio of the resonant circuit, wherein the voltage ratio is a ratio of a voltage of the energy absorbed by the receiver at resonance and a voltage of the energy absorbed by the receiver at a fixed frequency shift from resonance.

Claims

1. A moisture sensor comprising:

an electrical circuit embeddable into a material and having an inductor, a first capacitor and a second capacitor, and wherein the dielectric of the second capacitor is configured to be the material when the electrical circuit is embedded, and wherein the capacitance of the first capacitor is larger than the capacitance of the second capacitor such that the resonant frequency of the electrical circuit is not substantially altered by changes in capacitance of the second capacitor.

2. The moisture sensor of claim 1, wherein the material is selected from the group consisting of concrete, asphalt, thermal insulator, electrical insulator and air.

3. The moisture sensor of claim 1, wherein the inductor, the first capacitor and the second capacitor are each connected in parallel.

4. The moisture sensor of claim 1, wherein the second capacitor includes two leads extending from the electrical circuit.

5. The moisture sensor of claim 1, wherein the electrical circuit is surrounded by a electrically insulating protective case and wherein the second capacitor includes leads extending outside of the protective case.

6. A measurement device comprising:

a transmitter configured to transmit energy by sweeping across a frequency range;

a receiver configured to remotely measure energy absorbed by a resonant circuit that is in a field of the transmitted energy;

a means for automatically determining a resonant frequency of the resonant circuit from the energy absorbed by the receiver; and

a means for automatically determining at least one of;

an estimated or precise resistance of the resonant circuit;

an estimated or precise quality factor of the resonant circuit; and

an estimated or precise voltage ratio of the resonant circuit, wherein the voltage ratio is a ratio of a voltage of the energy absorbed by the receiver at resonance and a voltage of the energy absorbed by the receiver at a fixed frequency shift from resonance.

7. The measurement device of claim 6, wherein the receiver is configured to remotely measure energy absorbed by a resonant circuit that is the embedded in a material.

8. The measurement device of claim 7, further comprising a comprising a screen for displaying an estimated or precise relative moisture of the material.

9. The measurement device of claim 6, further comprising a means for at least one of estimating and determining a 3 db bandwidth of the resonant circuit.

10. The measurement device of claim 6, wherein the fixed frequency shift is at or about a 3 db bandwidth point of the resonant circuit.

11. The measurement device of claim 6, further comprising an actuation mechanism configured to automatically shift the frequency of the transmitted energy to about a 3 db bandwidth point of the resonant circuit.

12. The measurement device of claim 6, further comprising a screen for displaying at least one of:

the resonant frequency of the resonant circuit;

the estimated or precise resistance of the resonant circuit;

the estimated or precise quality factor of the resonant circuit; and

the estimated or precise voltage ratio of the resonant circuit.

13. The measurement device of claim 6, wherein the means for automatically determining the resonant frequency of the resonant circuit from the energy absorbed by the receiver comprises a processor in communication with the transmitter and the receiver.

14. The measurement device of claim 13, wherein the processor is configured to control scanning of the transmitter such that the transmitter scans back and forth across a frequency range in response to the energy absorbed by the receiver to determine the maximum energy absorbed by the receiver, wherein the frequency at which the maximum energy is absorbed corresponds to the resonant frequency of the resonant circuit.

15. The measurement device of claim 6, wherein the transmitter and the receiver each include one or more loops, and wherein the loops are aligned such that the coupling between them is nulled for a broad range of frequencies when the loops are not in the proximity of a resonant circuit.

16. A method of interrogating a resonant circuit comprising:

remotely automatically determining a resonant frequency of an electrical circuit with a measurement device, wherein the determining is accomplished automatically; and

remotely automatically determining at least one of;

an estimated or precise resistance of the resonant circuit;

an estimated or precise quality factor of the resonant circuit; and

an estimated or precise voltage ratio of the resonant circuit, wherein the voltage ratio is a ratio of a voltage of the energy absorbed by the receiver at resonance and a voltage of the energy absorbed by the receiver at a fixed frequency shift from resonance.

17. The method of detecting moisture of claim 16, further comprising displaying on a screen at least one of:

the resonant frequency of the electrical circuit;

the estimated or precise resistance of the resonant circuit;

an estimated or precise relative percentage of moisture in the material;

the estimated or precise quality factor of the resonant circuit; and

the estimated or precise voltage ratio of the resonant circuit.

18. The method of detecting moisture of claim 16, further comprising sweeping, with a transmitter, across a frequency range.

19. The method of detecting moisture of claim 16, further comprising locating a transmission loop of the measurement device directly above the resonant circuit.

20. The method of detecting moisture of claim 16, further comprising remotely determining a relative moisture level in the material.

21. The method of determining moisture of claim 16, further comprising embedding a resonant circuit into a material, wherein a dielectric of a capacitor of the resonant circuit is the material;