Devices with surface bound ionic liquids and method of use thereof

• US 20070231918A1
• Filed: 03/20/2007
• Published: 10/04/2007
• Est. Priority Date: 03/30/2006
• Status: Active Grant

• Current Assignee: Oakland University
• Original Assignee: Oakland University
• Inventors: Zeng, Xiangqun
• Granted Patent: US 7,886,577 B2
• Time in Patent Office: Days
• US Class Current: 436/141
• CPC Class Codes: G01N 2291/0257 with a layer containing at least one organic compound
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: Y10T 436/214 Acyclic [e.g., methane, octane, isoparaffin, etc.]

Abstract

An ionic liquid bound on an exposed surface of a device such as for detecting organic chemicals, preferably a gas sensor is described. The gas sensor can operate at high temperatures with a fast linear response which is also reversible. At high temperatures, the frequency change (Δf) versus concentration (C) curve mirrors the Henry'"'"'s gas law, such that the concentration of a gas sample in liquid solvent is proportional to the concentration or partial pressure of the sample in gas phase. A single gas sensor, or an array of sensors, can be used for the detection and quantitative analysis of gas vapors.

Claims

1. A device which comprises:

(a) a substrate with an exposed surface; and

(b) an ionic liquid film which is bound to the exposed surface so as to enable the ionic liquid to solvate an organic chemical which would be solvated by an unbound film of the ionic liquid.

2. The device of claim 1 wherein the ionic liquid film is phosphonium dodecylbenzene-sulfonate.

3. The device of claim 2 wherein the phosphonium dodecylbenzene-sulfonate is P6,6,6,14 DBS.

4. The device of claim 1, wherein the ionic liquid film is bound to the surface by means of a self-assembled monolayer (SAM).

5. The device of claim 4, wherein the self-assembled monolayer (SAM) comprises carboxylic acid terminal groups or pyridine terminal groups.

6. The device of claim 1, wherein the ionic liquid film is bound to the surface by means of one or more polyelectrolyte or conductive polymer on the surface.

7. The device of claim 6, wherein the conductive polymer is polyaniline.

8. The device of claim 1, wherein the ionic liquid film is bound to the surface by means of one or more polyionic or zwitterionic liquids.

9. The device of claim 8, wherein at least one of the zwitterionic liquids comprise imidazolium, tetraalkylammonium or tetraalkylphosphonium groups.

10. The device of claim 9, wherein the zwitterionic liquid further comprises sulfonate groups.

11. The device of claim 1, wherein the organic chemical is methane.

12. A method of solvating an organic sample comprising:

(a) providing a device which comprises a substrate with an exposed surface; and

an ionic liquid film which is bound to the exposed surface so as to enable the ionic liquid to solvate an organic chemical which would be solvated by an unbound film of the ionic liquid; and

(b) providing the organic chemical on the exposed surface of the ionic liquid film so that the film solvates the organic chemical.

13. The method of claim 12 wherein the ionic liquid is phosphonium dodecylbenzene-sulfonate.

14. The method of claim 13 wherein the phosphonium dodecylbenzene-sulfonate is P_6,6,6,14 DBS.

15. The method of claim 12, wherein the organic chemical is methane.

16. A gas sensor for determining the concentration of an organic vapor in a gaseous sample comprising:

(a) a quartz crystal microbalance having a transducer surface; and

(b) an ionic liquid film bound to the transducer surface of the quartz crystal microbalance, wherein when the organic vapor is present in the gaseous sample it is absorbed in the ionic liquid film on the transducer surface and changes a resonant frequency of the quartz crystal microbalance.

17. The gas sensor of claim 16, wherein the ionic liquid film is bound to the surface by means of a self-assembled monolayer (SAM).

18. The gas sensor of claim 17, wherein the self-assembled monolayer (SAM) comprises carboxylic acid terminal groups or pyridine terminal groups.

19. The gas sensor of claim 16, wherein the ionic liquid film is bound to the surface by means of one or more polyelectrolyte or conductive polymer on the surface.

20. The gas sensor of claim 19, wherein the conductive polymer is polyaniline.

21. The gas sensor of claim 16, wherein the ionic liquid film is bound to the surface by means of one or more polyionic or zwitterionic liquids.

22. The gas sensor of claim 21, wherein at least one of the zwitterionic liquids comprise imidazolium, tetraalkylammonium or tetraalkylphosphonium groups.

23. The gas sensor of claim 22, wherein the zwitterionic liquid further comprises sulfonate groups.

24. The gas sensor of claim 16, wherein the organic chemical is methane.

25. A method of determining the concentration of an organic vapor in a gaseous sample comprising:

(a) providing a gas sensor for detecting the concentration of an organic vapor in a gaseous sample comprising a quartz crystal microbalance having a transducer surface; and

an ionic liquid film bound on the transducer surface of the quartz crystal microbaiance, wherein when the organic vapor is present in the gaseous sample it is absorbed in the ionic liquid film on the transducer surface and changes a resonant frequency of the quartz crystal microbalance;

(b) providing a reference gas to the transducer surface of the gas sensor;

(c) measuring a first reference frequency of the gas sensor;

(d) providing the gaseous sample to the transducer surface of the gas sensor;

(e) measuring a second resonant frequency of the gas sensor;

(f) subtracting the first resonant frequency from the second resonant frequency to provide a frequency change; and

(g) determining the concentration of the organic vapor in the gaseous sample by the frequency change.

26. The method of claim 25 wherein the ionic liquid is phosphonium dodecylbenzene-sulfonate.

27. The method of claim 26 wherein the phosphonium dodecylbenzene-sulfonate is P_6,6,6,14 DBS.

28. A method of determining the concentration of an organic vapor in a gaseous sample comprising:

(a) providing a first gas sensor and a second gas sensor, the first and second gas sensors for detecting the concentration of an organic vapor in a gaseous sample, the sensors comprising a quartz crystal microbalance having a transducer surface, and an ionic liquid film bound on the transducer surface of the quartz crystal microbalance, wherein when the organic vapor is present in the gaseous sample it is absorbed in the ionic liquid film on the transducer surface and changes a resonant frequency of the quartz crystal microbalance;

(b) providing a reference gas to the first gas sensor;

(c) providing the gaseous sample to the second gas sensor;

(d) measuring a resonant frequency of the first sensor;

(e) measuring a resonant frequency of the second sensor;

(f) subtracting the resonant frequency of the first sensor from the resonant frequency of the second sensor to provide a frequency difference; and

(g) determining the concentration of the organic vapor in the gaseous sample by the frequency difference.

29. The method of claim 28 wherein the ionic liquid is phosphonium dodecylbenzene-sulfonate.

30. The method of claim 29 wherein the phosphonium dodecylbenzene-sulfonate is P_6,6,6,14 DBS.

31. A method of detecting an unknown organic vapor in a gaseous sample comprising:

(a) providing an array of gas sensors for detecting an organic vapor in a gaseous sample, each of the sensors comprising a quartz crystal microbalance having a transducer surface, and an ionic liquid film bound on the transducer surface, wherein when the organic vapor is present in the gaseous sample it is absorbed in the ionic liquid film on the transducer surface and changes a resonant frequency of the quartz crystal microbalance;

(b) providing a reference gas to the array;

(c) measuring a reference frequency of each of the sensors in the array;

(d) providing the gaseous sample to the array;

(e) measuring a resonant frequency of each of the sensors of the array;

(f) subtracting the resonant frequency of each of the sensors from the resonant frequency of each of the sensors to provide a frequency difference for each of the sensors of the array; and

(g) detecting the organic vapor in the gaseous sample by the frequency difference for each of the sensors in the array.