Thermomagnetic resonator-based temperature sensing

• US 9,618,396 B1
• Filed: 02/07/2014
• Issued: 04/11/2017
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Song, Hyok J, Chang, Chia-Ming
• Primary Examiner(s): Jagan, Mirellys
• Application Number:
  US14/176,020
• Time in Patent Office: 1,159 Days
• Field of Search: 374117, 374176, 374184
• CPC Class Codes: G01K 13/08 in rotary movement
• CPC Class Codes: G01K 7/36 using magnetic elements, e.g. magnets, coils magnetic elements per se H01F

Abstract

A thermomagnetic temperature sensor, a temperature measurement system and a method of measuring temperature employ a temperature-dependent resonant frequency of a thermomagnetic resonator to measure temperature. The thermomagnetic temperature sensor includes a thermomagnetic inductor and a capacitor connector to form the thermomagnetic resonator. The thermomagnetic inductor includes a ferromagnetic material having a temperature-dependent magnetic permeability to determine the temperature-dependent resonant frequency. A predetermined relationship between the temperature-dependent resonant frequency and temperature in a range between a maximum magnetic permeability value and a Curie temperature provides the measurement of temperature.

Claims

1. A thermomagnetic temperature sensor comprising:

a thermomagnetic inductor, a conductor of a coil of the thermomagnetic inductor comprising a ferromagnetic material with an engineered, temperature-dependent magnetic permeability; and

a capacitor connected in parallel to the thermomagnetic inductor to form a thermomagnetic resonator having a temperature-dependent resonant frequency that is determined by the temperature-dependent magnetic permeability,

wherein the temperature-dependent resonant frequency of the thermomagnetic resonator is characterized as a function of temperature.

2. The thermomagnetic temperature sensor of claim 1, wherein the engineered temperature-dependent magnetic permeability is characterized by a maximum value at a temperature below a Curie temperature of the ferromagnetic material, the temperature-dependent magnetic permeability monotonically decreasing as a function of temperature between a temperature corresponding to the maximum value and the Curie temperature, and wherein the temperature-dependent resonant frequency is characterized as a function of temperature between the Curie temperature and the temperature corresponding to the maximum value of the temperature-dependent magnetic permeability.

3. The thermomagnetic temperature sensor of claim 1, wherein the ferromagnetic material of the thermomagnetic inductor coil conductor comprises nickel.

4. The thermomagnetic temperature sensor of claim 1, wherein the temperature-dependent resonant frequency ranges from about 10 hertz to about 500 kilohertz.

5. A thermomagnetic temperature sensor comprising:

a thermomagnetic inductor, a conductor of a coil of the thermomagnetic inductor comprising a ferromagnetic material with an engineered, temperature-dependent magnetic permeability;

a capacitor connected to the thermomagnetic inductor to form a thermomagnetic resonator having a temperature-dependent resonant frequency that is determined by the temperature-dependent magnetic permeability, wherein the temperature-dependent resonant frequency of the thermomagnetic resonator is characterized as a function of temperature; and

an emitter to wirelessly excite the thermomagnetic resonator, the emitter being spaced apart from and magnetically coupled to the thermomagnetic inductor, wherein the emitter comprises an emitter coil spaced apart from the thermomagnetic resonator, the emitter coil to produce a magnetic flux that magnetically couples to the coil of the thermomagnetic inductor.

6. The thermomagnetic temperature sensor of claim 5, wherein the emitter is to employ an alternating magnetic field having a frequency below a frequency at which a skin depth of an induced current in the thermomagnetic inductor is greater than about one half of a thickness of the conductor of the coil of the thermomagnetic inductor.

7. The thermomagnetic temperature sensor of claim 5, wherein the emitter is stationary and the thermomagnetic resonator is configured to be mobile with respect to the stationary emitter.

8. A temperature measurement system comprising the thermomagnetic temperature sensor of claim 5, further comprising an impedance analyzer to drive the emitter and determine an impedance of the thermomagnetic temperature sensor as a function of frequency, the impedance having a peak corresponding to the temperature-dependent resonant frequency.

9. A temperature measurement system comprising:

a thermomagnetic temperature probe comprising a ferromagnetic material and a resonator, the ferromagnetic material having a temperature-dependent magnetic permeability that decreases monotonically as a function of temperature between a maximum value at a temperature below a Curie temperature of the ferromagnetic material and the Curie temperature, the resonator having a resonant frequency determined by the temperature-dependent magnetic permeability of the ferromagnetic material; and

a temperature measurement apparatus to measure a temperature of the thermomagnetic temperature probe using the resonant frequency according to a predetermined relationship between temperature and the resonant frequency,

wherein the temperature measurement apparatus comprises an emitter spaced apart from the thermomagnetic temperature probe, the emitter to be magnetically coupled to an inductor of the thermomagnetic temperature probe.

10. The temperature measurement system of claim 9, wherein the thermomagnetic temperature probe comprises an inductor connected to a capacitor to form the resonator, a conductor of a coil of the inductor comprising the ferromagnetic material.

11. The temperature measurement system of claim 9, wherein the temperature measurement apparatus further comprises an impedance measurement system to drive the emitter and determine an impedance of the resonator as a function of frequency, the impedance to have a peak at a frequency corresponding to the resonant frequency.

12. The temperature measurement system of claim 9, wherein the thermomagnetic temperature probe comprises an inductor connected to a capacitor to form the resonator, the inductor comprising a conductor disposed around a magnetic core comprising the ferromagnetic material.

13. The temperature measurement system of claim 12, wherein the ferromagnetic material of the thermomagnetic temperature probe comprises nickel, and wherein the resonant frequency of the resonator is less than about 500 kilohertz.

14. A temperature measurement system comprising:

a thermomagnetic temperature probe comprising a ferromagnetic material and a resonator, the ferromagnetic material having a temperature-dependent magnetic permeability that decreases monotonically as a function of temperature between a maximum value at a temperature below a Curie temperature of the ferromagnetic material and the Curie temperature, the resonator having a resonant frequency determined by the temperature-dependent magnetic permeability of the ferromagnetic material; and

a temperature measurement apparatus to measure a temperature of the thermomagnetic temperature probe using the resonant frequency according to a predetermined relationship between temperature and the resonant frequency,

wherein the thermomagnetic temperature probe further comprises an antenna coupled to the resonator, the antenna to couple the temperature measurement apparatus to the resonator and to facilitate determination of the resonant frequency of the resonator by the temperature measurement apparatus.

15. A method of measuring temperature, the method comprising:

providing a thermomagnetic temperature sensor in an environment, the provided thermomagnetic temperature sensor comprising a ferromagnetic material and a resonator, the ferromagnetic material having a temperature-dependent magnetic permeability with a monotonically decreasing value between a temperature corresponding to a maximum value below a Curie temperature of the ferromagnetic material and the Curie temperature, the resonator having a resonant frequency determined by the temperature-dependent magnetic permeability;

measuring the resonant frequency of the resonator comprising wirelessly coupling to the resonator to excite a resonance of the resonator; and

determining a temperature local to the thermomagnetic temperature sensor according to a predetermined relationship between the temperature-dependent resonant frequency and temperature.

16. The method of measuring temperature of claim 15, wherein the resonator comprises an inductor connected in parallel to a capacitor, and wherein a conductor of the inductor comprises the ferromagnetic material.

17. The method of measuring temperature of claim 15, wherein wirelessly coupling to the resonator comprising magnetically coupling between an emitter coil and a coil of the resonator.