ORGANIC CHEMICAL SENSOR COMPRISING PLASMA-DEPOSITED MICROPOROUS LAYER, AND METHOD OF MAKING AND USING

• US 20110031983A1
• Filed: 09/30/2008
• Published: 02/10/2011
• Est. Priority Date: 10/05/2007
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: O'Bryan, Nelson B., Wendland, Michael S., Rakow, Neal A., David, Moses M., Gryska, Stefan H.
• Granted Patent: US 8,378,694 B2
• Time in Patent Office: Days
• US Class Current: 324/663
• CPC Class Codes: G01N 27/125 Composition of the body, e.g. the composition of its sensitive layer
• CPC Class Codes: Y10T 442/624 Microfiber is carbon or carbonaceous

Abstract

Applicant discloses a sensing element for sensing an organic chemical analyte, comprising a first electrode and a second electrode, and a microporous, hydrophobic, analyte-responsive dielectric material disposed at least in proximity to the first and second electrodes. The analyte-responsive dielectric material may be an amorphous random covalent network comprising a mean pore size of less than about 10 nm and a porosity of at least about 20%. An electrical property of the sensing element, such as capacitance, can be monitored in order to sense an organic chemical analyte.

Claims

1. A sensor for sensing an organic chemical analyte, comprising:

a sensing element that comprises a first electrode and a second electrode and a microporous, hydrophobic, analyte-responsive dielectric material disposed at least in proximity to the first and second electrodes, wherein the microporous, hydrophobic analyte-responsive dielectric material comprises an amorphous random covalent network comprising at least about 30% carbon, and having a mean pore size of less than about 10 nm and a porosity of at least about 20%; and

,

an operating circuit in electrical communication with the first and second electrodes, wherein the operating circuit is capable of applying a voltage to the first and second electrodes and is capable of detecting a change in an electrical property of the sensing element.

2. The sensor of claim 1 wherein the amorphous random covalent network also comprises silicon, oxygen, and hydrogen.

3. The sensor of claim 1 wherein the amorphous random covalent network comprises essentially 100% carbon.

4. The sensor of claim 1 wherein the amorphous random covalent network comprises a porosity of at least about 30%.

5. The sensor of claim 1 in which at least one of the electrodes is permeable to an organic chemical analyte.

6. The sensor of claim 5 wherein the permeable electrode comprises a discontinuous layer of conductive material.

7. The sensor of claim 1 wherein the sensing element comprises a parallel-plate capacitor configuration.

8. The sensor of claim 1 wherein the sensing element comprises an interdigitated capacitor configuration.

9. The sensor of claim 1 wherein the sensing element comprises a cover layer in proximity to at least one of the electrodes, the cover layer being permeable to an organic chemical analyte.

10. A method of making an organic chemical analyte sensing element, comprising,

providing a substrate with a conductive layer;

forming a plasma from a gas mixture comprising an organosilane, oxygen, and a hydrocarbon;

exposing the substrate with conductive layer thereupon to the plasma such that an amorphous random covalent network layer comprising at least about 30% carbon, and further comprising silicon, hydrogen, and oxygen, is formed atop the conductive layer;

heating the amorphous random covalent network to form an analyte-responsive dielectric layer that comprises a microporous, hydrophobic, amorphous random covalent network having a mean pore size of less than about 10 nm and a porosity of at least about 20%; and

,

depositing a second conductive layer atop the analyte-responsive dielectric layer.

11. The method of claim 10 wherein the analyte-responsive dielectric layer comprises a porosity of at least about 30%.

12. The method of claim 10, wherein the second conductive layer is permeable to an organic chemical analyte of interest.

13. A method of making an organic chemical analyte sensing element, comprising,

providing a substrate with first and second conductive electrodes that are in an interdigitated configuration with spaces in between;

forming a plasma from a gas mixture comprising an organosilane, oxygen, and a hydrocarbon;

exposing the substrate with conductive electrodes thereupon to the plasma such that an amorphous random covalent network layer comprising at least about 30% carbon, and further comprising silicon, hydrogen, and oxygen, is formed at least in the spaces in between the interdigitated electrodes;

heating the amorphous random covalent network to form an analyte-responsive dielectric layer that comprises a microporous, hydrophobic, amorphous random covalent network having a mean pore size of less than about 10 nm and a porosity of at least about 20%.

14. The method of claim 13 wherein the analyte-responsive dielectric layer comprises a porosity of at least about 30%.

15. A method of sensing organic chemical analytes, comprising:

providing a sensor that comprises;

a sensing element that comprises a first electrode and a second electrode and a microporous, hydrophobic, analyte-responsive dielectric material disposed at least in proximity to the first and second electrodes, wherein the microporous, hydrophobic analyte-responsive dielectric material comprises an amorphous random covalent network comprising at least about 30% carbon, and having a mean pore size of less than about 10 nm and a porosity of at least about 20%; and

,

an operating circuit in electrical communication with the first and second electrodes, wherein the operating circuit is capable of applying a voltage to the first and second electrodes and is capable of detecting a change in an electrical property of the sensing element;

exposing the sensing element to an environment potentially containing one or more organic chemical analytes;

applying a voltage to the first and second electrodes; and

,

monitoring an electrical property of the sensing element.

16. The method of claim 15 wherein the amorphous random covalent network also comprises silicon, oxygen, and hydrogen.

17. The method of claim 15 wherein the amorphous random covalent network comprises essentially 100% carbon.

18. The method of claim 15 wherein the analyte-responsive dielectric layer comprises a porosity of at least about 30%.

19. The method of claim 15 wherein the sensing element comprises a capacitor, and wherein the electrical property that is monitored is an capacitive property of the sensing element.

20. The method of claim 15 wherein the property that is measured is the capacitance of the sensing element.