Detection of trace chemicals and method therefor
The invention provides devices, systems, and methods for detecting an analyte vapor. Particularly, electronegative analyte vapors, such as those vapors evolving from explosive compounds, are typical analytes detected the devices. The devices operate using a resistivity change mechanism wherein a nanostructured chemiresistive material undergoes a resistivity change in the presence of an analyte vapor. A resistivity change indicates the presence of an analyte.
1. A device for detecting an electronegative analyte vapor, comprising:
(a) a film comprising a nanostructured chemiresistive material having a first resistivity in the absence of an electronegative analyte vapor and a second resistivity, different than the first resistivity, after exposure to the electronegative analyte vapor, wherein the nanostructured chemiresistive material is a three-dimensional mesh that comprises a plurality of nanostructured materials selected from the group consisting of nanowires, nanotubes, nanoparticles, and mixtures thereof, and wherein the nanostructured chemiresistive material comprises monoclinic titanium dioxide; and
(b) a resistivity-measuring device sized and configured to determine a resistivity of the film, wherein the resistivity measuring device comprises a first electrode and a second electrode on a surface of the film and spaced a distance apart from each other such that the first electrode is in resistive communication with the second electrode through a first sensing region of the film.
2. The device of claim 1 , wherein the resistivity measuring device is sized and configured to electrically determine the resistivity between the first electrode and the second electrode through the first sensing region.
3. The device of claim 1 , wherein the nanostructured chemiresistive material comprises monoclinic titanium dioxide nanowires.
4. The device of claim 1 , wherein the nanostructured chemiresistive material further comprises gold nanoparticles.
5. The device of claim 1 , wherein the nanostructured chemiresistive material comprises a functionalized surface.
6. The device of claim 1 , wherein the nanostructured chemiresistive material comprises a first nanostructured chemiresistive material and a second nanostructured chemiresistive material.
7. The device of claim 6 , wherein the resistivity measuring device is sized and configured to measure the resistivity of the first nanostructured chemiresistive material and the second nanostructured chemiresistive material separately.
8. The device of claim 1 , wherein the difference between the first resistivity and the second resistivity results from the formation of a charge carrier depletion region at an interface between the nanostructured chemiresistive material and the electronegative analyte vapor.
9. The device of claim 1 , wherein the first resistivity is less than the second resistivity.
10. The device of claim 1 , wherein the electronegative analyte vapor is a nitroaromatic compound vapor.
11. The device of claim 1 , wherein the electronegative analyte vapor is a vapor of a compound selected from the group consisting of trinitrotoluene, dinitrotoluene, cyclotetramethylenetetranitramine, cyclotrimethylenetrinitramine, 2,4,6-trinitrophenol, methyl-2,4,6-trinitrophenyInitramine, pentaerythritol-tetranitrate, silicon-pentaerythritol-tetranitrate, nitroglycerine, and mixtures thereof.
12. The device of claim 2 , further comprising:
a third electrode in contact with the film, a fourth electrode in contact with the film, and a second sensing region of the film intermediate the third electrode and the fourth electrode, such that the third electrode is in resistive communication with the fourth electrode through the second sensing region, wherein the second sensing region comprises a plurality of nanostructured materials in between the third electrode and the fourth electrode;
wherein the resistivity-measuring device is sized and configured to electrically determine the resistivity between the third electrode and the fourth electrode through the second sensing region for comparison to the determined resistivity in the first sensing region; and
wherein the first electrode and the second electrode are spaced a first distance apart from each other on the film, wherein the third electrode and the fourth electrode are spaced a second distance apart from each other on the film, and wherein the first distance and the second distance are different.