Wireless chemical sensing method

Patent metadata

Field	Value
Publication number	US-9733203-B2
Application number	US-201615141217-A
Country	US
Kind code	B2
Filing date	Apr 28, 2016
Priority date	May 9, 2008
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

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.

First claim

The invention claimed is:

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.

Assignees

• Nasa

Inventors

• Woodard Stanley E
• Oglesby Donald M
• Taylor Bryant D

Classifications

• G01N27/021 Primary

  before and after chemical transformation of the material · CPC title

• G01N27/26 Primary

  by investigating electrochemical variables; by using electrolysis or electrophoresis · CPC title

• G01N27/72

  by investigating magnetic variables · CPC title

• G01N27/122

  Circuits particularly adapted therefor, e.g. linearising circuits · CPC title