Wireless chemical sensing method

• US 9,733,203 B2
• Filed: 04/28/2016
• Issued: 08/15/2017
• Est. Priority Date: 05/09/2008
• 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, Stanley E., Oglesby, Donald M., Taylor, Bryant D.
• Primary Examiner(s): Xu, Robert
• Application Number:
  US15/141,217
• Publication Number:
  US 20160238561A1
• Time in Patent Office: 474 Days
• Field of Search: None
• CPC Class Codes: G01N 27/021 before and after chemical transformation of the material
• CPC Class Codes: G01N 27/122 Circuits particularly adapted therefor, e.g. linearising circuits
• CPC Class Codes: G01N 27/26 by investigating electrochemical variables; by using electrolysis or electrophoresis
• CPC Class Codes: G01N 27/72 by investigating magnetic variables

Abstract

A wireless chemical sensor includes an electrical conductor and a material separated therefrom by an electric insulator. The electrical conductor is an unconnected open-circuit shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the first electrical conductor resonates to generate harmonic electric and magnetic field responses. The material is positioned at a location lying within at least one of the electric and magnetic field responses so-generated. The material changes in electrical conductivity in the presence of a chemical-of-interest.

Claims

1. A method of sensing the presence of a chemical-of-interest, comprising the steps of:

providing an electrical conductor having first and second ends and shaped between said first and second ends for storage of 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, amplitude and bandwidth associated therewith;

positioning a material in a spaced-apart relationship with respect to said electrical conductor at a location lying within at least one of said electric and magnetic field responses so-generated, said material selected to affect attenuation of energy associated with said electric and magnetic field responses so-generated in the presence of a chemical-of-interest;

disposing an electric insulator between said electrical conductor and said material;

recording a baseline response for said at least one of said electric and magnetic field responses so-generated when the chemical-of-interest is not present; and

monitoring said at least one of said electric and magnetic field responses so-generated for changes with respect to said baseline response as an indication of the presence of the chemical-of-interest.

2. A method according to claim 1, wherein said step of disposing comprises the step of encasing said electrical conductor in said electric insulator.

3. A method according to claim 1, wherein said electrical conductor comprises a thin-film trace.

4. A method according to claim 3, wherein the width of said trace is selected from the group consisting of uniform and non-uniform.

5. A method according to claim 3, where the spacing between adjacent portions of said trace are selected from the group consisting of uniform and non-uniform.

6. A method according to claim 1, wherein said material is adapted to absorb the chemical-of-interest.

7. A method according to claim 1, wherein said material is adapted to chemically react with the chemical-of-interest.