Portable Electrochemical Multiphase Microreactor for Sensing Trace Chemical Vapors

• US 20110284394A1
• Filed: 02/14/2008
• Published: 11/24/2011
• Est. Priority Date: 02/14/2007
• Status: Abandoned Application

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Oh, Ilwhan, Monty, Chelsea, Masel, Richard I.
• Application Number:
  US12/525,873
• Publication Number:
  US 20110284394A1
• Time in Patent Office: Days
• US Class Current: 205/783
• CPC Class Codes: G01N 27/40 Semi-permeable membranes or partitions
• CPC Class Codes: G01N 27/4035 Combination of a single ion-sensing electrode and a single reference electrode G01N27/406 and G01N27/413 take precedence
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A multiphase microreactor includes gas and liquid microchannels separated by a nanoporous membrane. Rapid mass transfer of gas samples into the liquid electrolyte allows the microchannel/membrane assembly to be used as a fast and sensitive gas sensor. When the oxime chemistry is adapted into the microchannel sensor, the microchannel sensor selectively responds to organophosphates and organophosphate simulants. In addition, a double microchannel design may be used to reduce voltage drift and incorporate a reference electrode into the sensor assembly. Methods of detecting organophosphates are also disclosed.

Claims

1. A microchannel system comprising:

a liquid microchannel;

a gas microchannel;

a membrane arranged between said liquid microchannel and said gas microchannel, wherein said membrane has hydrophobic properties; and

an ion selective electrode contacting said liquid microchannel.

2. The microchannel system of claim 1, further comprising a reference electrode coupled to an outlet of said liquid microchannel.

3. The microchannel system of claim 1, wherein said membrane is a nanoporous membrane having a pore size diameter in the range of about 50 nm and about 400 microns.

4. The microchannel system of claim 3, wherein said liquid microchannel and said gas microchannel has a depth in the range of about 0.2 mm to about 0.05 mm.

5. The microchannel system of claim 4 wherein said membrane having a thickness of between about 2 microns and about 500 microns.

6. The microchannel system of claim 4, wherein said liquid microchannel has width in the range of about 1 mm and about 0.05 mm.

7. The microchannel system of claim 1, wherein said ion selective electrode includes at least one element selected from the group consisting of gold and silver.

8. The microchannel system of claim 7, wherein said membrane is a polycarbonate membrane, and wherein said ion selective electrode is about 40 nm thick.

9. The microchannel system of claim 1, further comprising a coating on said membrane, wherein said coating causes said membrane to have the hydrophobic properties.

10. The microchannel system of claim 9, wherein said membrane is etched from a silicon on insulator.

11. The microchannel system of claim 1, wherein said membrane is a nanoporous membrane, and wherein a pore size diameter is based on the pressure in said liquid microchannel.

12. The microchannel system of claim 1, comprising a plurality of said liquid microchannels and a plurality of said gas microchannels.

13. The microchannel system of claim 12, wherein said plurality of said liquid microchannels share an inlet or an outlet.

14. The microchannel system of claim 1, wherein said liquid microchannel carries an electrolyte comprising an oxime solution.

15. The microchannel of claim 14 where the oxime solution comprises of 1-phenyl-1, 2, 3,-butanetrione 2-oxime (PBO) in a buffer.

16. The microchannel of claim 15, wherein the PBO concentration is in a range between about 10 μ

M and about 10 mM, and wherein the buffer has a pH of about 10.

17. The microchannel system of claim 1, wherein said liquid microchannel and said gas microchannel are formed from a polymer including specifically polydimethylsiloxane elastamer or polycarbonate.

18. A method of detecting organophosphates using a microchannel system having a liquid microchannel, a gas microchannel, and a membrane having hydrophobic properties, said method comprising the steps of:

coupling a reference electrode to an outlet of the liquid microchannel;

adding an electrolyte solution including an oxime compound to the liquid microchannel;

adding a gas including an organophosphate compound to the gas microchannel; and

measuring the open-circuit potential between the ion selective electrode and the reference electrode.

19. The method of claim 18, wherein the membrane has a pore size diameter in the range of about 50 nm and about 200 microns, and the membrane is arranged between the liquid microchannel and the gas microchannel;

and

wherein the oxime solution is of 1-phenyl-1,2,3,-butanetrione 2-oxime (PBO) in a borate buffer compound microchannel.

20. The method of claim 18, wherein the thickness of the membrane is between about 2 microns and about 500 microns.

21. A method of making a microchannel system comprising the steps of:

forming a gas microchannel;

forming a liquid microchannel configured to receive an oxime compound;

forming a membrane having hydrophobic properties;

arranging the membrane between the liquid microchannel and the gas microchannel;

arranging an ion selective electrode in contact with the liquid microchannel; and

arranging a reference electrode at an outlet of the liquid microchannel.

22. The method of claim 21, wherein said step of forming the membrane includes forming a nanoporous membrane having a pore size diameter in the range of about 50 nm and about 400 microns.

23. The method of claim 21, wherein said steps of forming the microchannels include forming the liquid microchannel and the gas microchannel to a depth in the range of about 0.2 mm to about 0.05 mm.

24. The method in claim 21 wherein said step of forming the membrane includes forming to a thickness of between about 2 microns and about 500 microns.

25. The method of claim 21, wherein said step of forming the liquid microchannel includes forming to a width in the range of about 1 mm and about 0.05 mm.

26. The method of claim 21, wherein the ion selective electrode includes at least one element selected from the group consisting of gold and silver.