Detecting compounds in airborne particles using ion exchange
A sensor to detect solid particles of a target salt can include a support substrate, an adsorption layer, a sensing layer oriented between the support substrate and the adsorption layer, and an electrode pair in contact with the sensing layer and separated by the sensing layer. The adsorption layer can include an ion exchange medium formed of a first porous structured material functionalized with basic or acidic functional groups. The basic or acidic functional groups can remove an acid or base component from the target salt to form a free base or free acid, respectively, of the target salt. The sensing layer can include a second porous structured material functionalized to detect the free base or acid of the target salt by a change in conductivity.
1 . A sensor to detect solid particles of a target compound, comprising:
a support substrate;
an adsorption layer comprising a medium formed of a first porous structured material functionalized with basic functional groups, wherein said target compound is a salt or a free base compound, wherein the salt is converted by the basic functional groups to form a converted free base of the salt, wherein the first porous structured material is a network of first organic nanofibers, wherein the first organic nanofibers are assembled from stacked molecules selected from a group consisting of: 3,4,9,10-perylene-tetracarboxylic diimide, 3,4,9,10-perylene-tetracarboxylic dianhydride, perylene 3,4,9,10-tetracarboxyl-3,4-anhydride-9,10-imide, an indolocarbazole derivative, and an oligomer made up of 3 to 9 carbazole derivative monomers, wherein at least a portion of the stacked molecules are further functionalized with the basic functional groups;
a sensing layer oriented between the support substrate and the adsorption layer, the sensing layer comprising a second porous structured material functionalized to detect the converted free base or the free base compound by a change in conductivity, wherein the first porous structured material comprises a different material than the second porous structured material; and
an electrode pair in contact with the sensing layer and separated by the sensing layer.
2 . The sensor of claim 1 , wherein the salt is a salt of an alkaloid or an opiate.
3 . The sensor of claim 1 , wherein the salt is fentanyl hydrochloride, and wherein the free base compound is carfentanil.
4 . The sensor of claim 1 , wherein the support substrate comprises glass, silicon, alumina, sapphire, mica, quartz, plastic, or a combination thereof.
5 . The sensor of claim 1 , wherein the basic functional groups include primary amino groups, secondary amino groups, tertiary amino groups, or a combination thereof.
6 . The sensor of claim 1 , wherein the basic functional groups include hexylamine, ethylethylamine, dimethylbutylamine, or a combination thereof.
7 . The sensor of claim 1 , wherein the second porous structured material comprises organic nanofibers, polymeric nanofibers, or a combination thereof.
8 . The sensor of claim 1 , wherein the second porous structured material is a network of second organic nanofibers.
9 . The sensor of claim 8 , wherein the basic functional groups are amines, wherein the first organic nanofibers are assembled from stacked molecules having at least one of the following structures:
10 . The sensor of claim 9 , wherein the second organic nanofibers are assembled from stacked molecules having at least one of the following structures:
11 . The sensor of claim 10 , wherein the at least one of the structures of the first organic nanofibers and the at least one of the structures of the second organic nanofibers, respectively, are: X and XIV; XI and XIV; or XII and XIV.
12 . The sensor of claim 1 , wherein the second porous structured material comprises second organic nanofibers assembled from stacked molecules selected from a group consisting of: substituted or unsubstituted 3,4,9,10-perylene-tetracarboxylic diimide, substituted or unsubstituted 3,4,9,10-perylene-tetracarboxylic dianhydride, substituted or unsubstituted perylene 3,4,9,10-tetracarboxyl-3,4-anhydride-9,10-imide, an indolocarbazole derivative, and an oligomer made up of 3 to 9 carbazole derivative monomers.
13 . The sensor of claim 1 , wherein the adsorption layer and the sensing layer each has a thickness from 50 nm to 5 μm.
14 . The sensor of claim 1 , wherein the adsorption layer and the sensing layer each has a mass from 0.1 μg to 6 μg per 3 mm 2 and an area of 0.1 mm 2 to 10 mm 2 .
15 . The sensor of claim 1 , wherein the adsorption layer is porous with an average pore size from 10 nm to 1 μm.
16 . The sensor of claim 1 , wherein the adsorption layer is in direct contact with the sensing layer.
17 . The sensor of claim 1 , wherein the electrode pair is separated by a gap distance from 50 nm to 100 μm.