Wireless temperature sensor having no electrical connections and sensing method for use therewith

• US 8,636,407 B2
• Filed: 02/17/2011
• Issued: 01/28/2014
• Est. Priority Date: 02/17/2010
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Woodard, Marie
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): Soto, Janice M
• Application Number:
  US13/029,426
• Publication Number:
  US 20110292969A1
• Time in Patent Office: 1,076 Days
• Field of Search: None
• US Class Current: 374/120
• CPC Class Codes: G01K 7/00 Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat giving results other than momentary value of temperature G01K3/00 ; Power supply therefor, e.g. using thermoelectric elements
• CPC Class Codes: G01K 7/38 the variations of temperature influencing the magnetic permeability

Abstract

A wireless temperature sensor includes an electrical conductor and a dielectric material on the conductor. The conductor is electrically unconnected and is shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the conductor resonates to generate harmonic electric and magnetic field responses, each of which has a frequency associated therewith. The material is selected such that it experiences changes in either dielectric or magnetic permeability attributes in the presence of a temperature change. Shifts from the sensor'"'"'s baseline frequency response indicate that the material has experienced a temperature change.

Claims

1. A wireless temperature sensor, comprising:

an electrical conductor in the form of a thin-film trace having first and second ends and shaped to form a pattern that can store an electric field and a magnetic field, said first and second ends remaining electrically unconnected such that said electrical conductor so-shaped defines an unconnected open-circuit having inductance and capacitance wherein, in the presence of a time-varying magnetic field, said electrical conductor so-shaped resonates to generate harmonic electric and magnetic field responses, each of which has a frequency associated therewith;

a material encasing said electrical conductor and uniformly distributed on said pattern, said material experiencing changes in dielectric properties in the presence of a temperature change; and

a field response recorder for wirelessly transmitting said time-varying magnetic field to said electrical conductor and for wirelessly detecting said frequency associated with said electric and magnetic field responses so-generated and resulting from said changes, said field response recorder storing a library of temperature-frequency response curves with each of said curves being associated with a particular damage to said pattern, wherein at least one of said curves is used to re-calibrate said field response recorder when said pattern is damaged.

2. A wireless temperature sensor as in claim 1, wherein said dielectric material is glass.

3. A wireless temperature sensor as in claim 1, wherein said material is selected from the group consisting of borofloat and soda-lime glass.

4. A method of sensing temperature, comprising the steps of:

providing an electrical conductor in the form of a thin-film trace having first and second ends and shaped to form a pattern that can store an electric field and a magnetic field, said first and second ends remaining electrically unconnected such that said electrical conductor so-shaped defines an unconnected open-circuit having inductance and capacitance wherein, in the presence of a time-varying magnetic field, said electrical conductor so-shaped resonates to generate harmonic electric and magnetic field responses, each of which has a frequency associated therewith;

encasing said electrical conductor with a material such that said material is uniformly distributed on said pattern, said material selected to experience changes in dielectric properties in the presence of a temperature change;

storing a library of temperature-frequency response curves with each of said curves being associated with a particular damage to said pattern;

wirelessly transmitting said time-varying magnetic field to said electrical conductor and wirelessly detecting said frequency associated with said electric and magnetic field responses so-generated and resulting from said changes; and

calibrating said electric and magnetic field responses so-generated using at least one of said frequency-temperature curves when said pattern is damaged.

5. A method of sensing temperature as in claim 4, wherein said material encasing said electrical conductor is glass.

6. A method of sensing temperature as in claim 4, wherein said material encasing said electrical conductor is selected from the group consisting of borofloat and soda-lime glass.