Conducting compositions for detection of fluoroalkyl substances and related articles, systems, and methods

Abstract

Conducting compositions for detection of fluoroalkyl substances (e.g., fluoroalkyl analytes), and related articles, systems, and methods, are generally described.

Description

[0001] CONDUCTING COMPOSITIONS FOR DETECTION OF FLUOROALKYL SUBSTANCES AND RELATED ARTICLES, SYSTEMS, AND METHODS

[0002] RELATED APPLICATIONS

[0003] This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63 / 656,093, filed June 4, 2024, and entitled “Conducting Compositions for Detection of Fluoroalkyl Substances and Related Articles, Systems, and Methods,” which is incorporated herein by reference in its entirety for all purposes.

[0004] TECHNICAL FIELD

[0005] Conducting compositions for detection of fluoroalkyl substances (e.g., fluoroalkyl analytes), and related articles, systems, and methods, are generally described.

[0006] BACKGROUND

[0007] Per- and polyfluoroalkyl substances (PFAS), known as “forever chemicals,” are a growing concern in the sphere of human and environmental health. In response, rapid, reproducible, and inexpensive methods for PFAS detection in the environment and home water supplies are needed.

[0008] SUMMARY

[0009] Generally described herein are conducting compositions, and related articles, systems, and methods, for detection of fluoroalkyl substances (e.g., fluoroalkyl analytes). The subject matter of the present invention involves, in some cases, interrelated products, alternative solutions to a particular problem, and / or a plurality of different uses of one or more systems and / or articles.

[0010] According to certain embodiments, a composition is described. In some embodiments, the composition comprises a conducting polymer comprising at least one fluorine-containing moiety, wherein the composition is configured such that the composition displays an increase in conductivity in response to a presence of a fluoroalkyl analyte.

[0011] In some embodiments, a composition comprises a conducting polymer and an additive comprising at least one fluorine-containing moiety, wherein the composition is configured such that the composition displays an increase in conductivity in response to a presence of a fluoroalkyl analyte.

[0012] According to some embodiments, a sensor is described. In certain embodiments, the sensor comprises a conducting material comprising at least one fluorine-containing moiety, wherein the conducting material is configured such that the sensor displays a change in conductivity in response to a presence of a fluoroalkyl analyte.

[0013] In certain embodiments, a sensor comprises a conducting material and an additive comprising at least one fluorine-containing moiety, wherein the conducting material is configured such that the sensor displays a change in conductivity in response to a presence of a fluoroalkyl analyte.

[0014] According to certain embodiments, a composition comprises a material comprising at least one fluorine-containing moiety, and having a first solubility. In certain embodiments, the material is configured to interact with a fluoroalkyl analyte to form a conjugate material comprising the fluoroalkyl analyte. In some embodiments, the conjugate material, in response to a stimulus, has a second solubility that is less than the first solubility.

[0015] In certain embodiments, a method comprises exposing a material comprising at least one fluorine-containing moiety to a sample suspected of comprising a fluoroalkyl analyte, thereby forming a conjugate material comprising the fluoroalkyl analyte, if present. In some embodiments, the method comprises exposing the conjugate material comprising the fluoroalkyl analyte, if present, to a sensor configured to detect the fluoroalkyl analyte.

[0016] Other advantages and novel features of the present invention will become apparent from the following Detailed Description of various non-limiting embodiments of the invention when considered in conjunction with the accompanying figures. In cases where the present specification and a document incorporated by reference include conflicting and / or inconsistent disclosure, the present specification shall control.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention. In the figures:

[0019] FIG. 1A shows, according to certain embodiments, a cross-sectional schematic diagram of a composition comprising a conducting polymer.

[0020] FIG. IB shows, according to certain embodiments, a cross-sectional schematic diagram of a composition comprising a conducting polymer and an additive.

[0021] FIG. 1C shows, according to certain embodiments, a cross-sectional schematic diagram of a composition comprising a composite structure.

[0022] FIG. 2A shows, according to certain embodiments, a cross-sectional schematic diagram of an article comprising the composition shown in FIG. 1A deposited on at least a portion of a substrate.

[0023] FIG. 2B shows, according to certain embodiments, a cross-sectional schematic diagram of an article comprising the composition shown in FIG. IB deposited on at least a portion of a substrate.

[0024] FIG. 2C shows, according to certain embodiments, a cross-sectional schematic diagram of an article comprising the composition shown in FIG. 1C deposited on at least a portion of a substrate.

[0025] FIG. 3A shows, according to certain embodiments, a cross-sectional schematic diagram of a sensor comprising a conducting material.

[0026] FIG. 3B shows, according to certain embodiments, a cross-sectional schematic diagram of a sensor comprising a conducting material and an additive.

[0027] FIG. 3C shows, according to certain embodiments, a cross-sectional schematic diagram of a sensor comprising a composite structure comprising a conducting material and one or more additional materials.

[0028] FIG. 4 shows, according to certain embodiments, a cross-sectional schematic diagram of a composition comprising a material comprising at least one fluorine- containing moiety, in accordance with certain embodiments.

[0029] FIG. 5 shows, according to certain embodiments, reaction schemes representing acid doping of poly aniline (top) and polypyrrole (bottom). FIG. 6 shows, according to certain embodiments, an exemplary structure of an additive comprising at least one fluorine-containing (e.g., fluoro alky 1-containing) moiety.

[0030] FIG. 7 shows, according to certain embodiments, non-limiting examples of conducting polymers comprising at least one fluorine-containing (e.g., fluoroalkyl- containing) moiety.

[0031] FIG. 8 shows, according to certain embodiments, non-limiting examples of conducting polymers.

[0032] FIG. 9 shows, according to certain embodiments, a reaction scheme representing the synthesis of polypyrrole to provide a sensing material.

[0033] FIG. 10 shows, according to certain embodiments, pH activated organic oxidants.

[0034] FIG. 11 shows, according to certain embodiments, exemplary fluorophilic polymers that aggregate with heating.

[0035] FIG. 12 shows, according to certain embodiments, photographs of a polymer that aggregates with heating.

[0036] FIG. 13 shows, according to certain embodiments, a non-limiting example of a polymer comprising an amine group that is soluble at pH levels when the amine is protonated and insoluble at pH levels when the amine is not protonated.

[0037] FIG. 14 shows, according to certain embodiments, doped and undoped structures of poly aniline (PANI).

[0038] FIG. 15 shows, according to certain embodiments, the preparation of fluorous PANI-EB dispersion by mixing PANI-EB nanofiber powder with the fluorous surfactant (KPD).

[0039] FIG. 16 shows, according to certain embodiments, a photograph of an electrical lateral flow assay (e-LFA) membrane and a schematic of the conductivity change after exposure to PFAS aqueous solution.

[0040] FIG. 17A shows, according to certain embodiments, a scanning electron microscopy (SEM) image of PANI-EB.

[0041] FIG. 17B shows, according to certain embodiments, a SEM image of F-PANI coatings formed on a NC membrane.

[0042] FIG. 18 shows, according to certain embodiments, plots of contact angle of water on PANI-EB and F-PANI coatings formed on a NB membrane and glass. FIG. 19 shows, according to certain embodiments, a schematic of the four-point probe measurement and experimental factors investigated.

[0043] FIG. 20 shows, according to certain embodiments, a plot of resistance values as a function of time after the sample was removed from the vial.

[0044] FIG. 21 shows, according to certain embodiments, a plot of resistance values as function of exposure time in the vial with 10'6M PFOA.

[0045] FIG. 22 shows, according to certain embodiments, a plot of resistance values for each width with 10'6M PFOA.

[0046] FIG. 23 shows, according to certain embodiments, a plot of resistance values for each width with 10'2M PFOA.

[0047] FIG. 24 shows, according to certain embodiments, a histogram of resistance values for each concentration of PFOA.

[0048] FIG. 25 shows, according to certain embodiments, plots of conductivity of F- PANI coatings on a NC membrane as a function of PFOA or OA concentrations.

[0049] FIG. 26 shows, according to certain embodiments, plots of conductivity of F- PANI coatings on NC membranes and filter paper as a function of PFOA concentrations.

[0050] FIG. 27 shows, according to certain embodiments, a summary of resistance and conductivity values of the wet F-PANI test line on a NC membrane as a function of PFOA concentration.

[0051] FIG. 28 shows, according to certain embodiments: (a) photographs of the interfacial polymerization of aniline over time points (top); (b) a transmission electron microscopy image of PANI nanofibers (bottom left); and (c) Fourier-transform infrared spectra of PANI-EB nanofibers (bottom right).

[0052] FIG. 29 shows, according to certain embodiments, photographs displaying the change in wettability of F-PANI coating over time.

[0053] FIG. 30 shows, according to certain embodiments, the synthesis of aniline monomers via S\Ar followed by a tin(II) chloride reduction.

[0054] FIG. 31A-31E show, according to certain embodiments, structures of perfluoroalkoxy-substituted nitro moieties.

[0055] FIG. 32 shows, according to certain embodiments, the synthesis of perfluoroalkoxy-substituted aniline moieties. FIGS. 33A-33E show, according to certain embodiments, structures of perfluoroalkoxy-substituted aniline moieties.

[0056] FIG. 34 shows, according to certain embodiments, the synthesis of PANI-F polymers via interfacial oxidative polymerization with ammonium persulfate followed by a potassium hydroxide reduction.

[0057] FIG. 35 shows, according to certain embodiments, the synthesis of aniline dimers via Buchwald Hartwig followed by a b2pin2 reduction.

[0058] FIGS. 36A-36F show, according to certain embodiments, structures of aniline dimers.

[0059] FIG. 37 shows, according to certain embodiments, the synthesis of PANI-F copolymers via interfacial oxidative polymerization with ammonium persulfate followed by a potassium hydroxide reduction.

[0060] FIG. 38 shows, according to certain embodiments, images of PANI-F copolymerization between 5 minute and 24 hour time stamps.

[0061] DETAILED DESCRIPTION

[0062] Generally described herein are compositions, and related articles, systems, and methods, for detection of fluoroalkyl substances (e.g., fluoroalkyl analytes). In certain embodiments, a composition comprises a conducting material (e.g., a conducting polymer). The composition may be fluorophilic such that the composition comprises at least one fluorine-containing moiety. The composition may, in certain embodiments, have an affinity for a fluoroalkyl substance, such as a perfluoroalkyl substance and / or a polyfluoroalkyl substance (PFAS). In certain embodiments, for example, the composition comprises a conducting material comprising at least one fluoroalkyl group that renders the composition fluorophilic. In other embodiments, the composition comprises a conducting material and at least one additional species comprising at least one fluoroalkyl group that renders the composition fluorophilic. The additional species may, in certain embodiments, be an additive that is dispersed within a matrix of the conducting material. In other embodiments, the additional species is a component of a composite structure with the conducting material, such as a layered structure comprising a layer of the additional species deposited on a layer of the conducting material. According to certain embodiments, the fluorophilic nature of the composition allows the composition to interact with a fluoroalkyl substance (e.g., a PFAS). In some embodiments, for example, the conducting material (e.g., conducting polymer) is configured to absorb the fluoroalkyl substance. Upon absorption, the fluoroalkyl substance may result in an increase in an electrical conductivity of the conducting material, in accordance with certain embodiments. For example, in some embodiments, the fluoroalkyl substance is an acidic species that is configured to acid dope a backbone of the conducting material, thereby resulting in an increase in charge carrier concentration and an increase in electrical conductivity of the conducting material. The increase in conductivity may advantageously be used to detect the fluoroalkyl substance.

[0063] In certain embodiments, an interaction with a fluoroalkyl substance may result in a decrease in an electrical conductivity of the conducting material. For example, in some embodiments, the fluoroalkyl substance is configured to decrease a charge carrier concentration of the conducting material, thereby resulting in a decrease in electrical conductivity of the conducting material. In certain embodiments, the fluoroalkyl substance is configured to decrease the charge carrier concentration of the conducting material via charge carrier pinning and / or a redox reaction. The decrease in conductivity may advantageously be used to detect the fluoroalkyl substance.

[0064] Articles and / or sensors comprising the conducting material (e.g., conducting polymer) are also described herein. In certain embodiments, for example, the article (e.g., sensor) comprises a composition comprising the conducting material deposited on a substrate. The article (e.g., sensor) may be configured to display a change in conductivity in response to a presence of the fluoroalkyl substance. The change in conductivity may be detected and used to determine the presence of the fluoroalkyl substance. In some embodiments, the article (e.g., sensor) comprises a resonant radio frequency circuit and / or a wireless transmitter that permits the change in conductivity to be detected wirelessly (e.g., by a smartphone). According to certain embodiments, the article (e.g., sensor) is a lateral flow assay that is configured to facilitate flow of a fluid (e.g., a liquid) via capillary action.

[0065] In certain embodiments, preconcentrating compositions and related methods are described. A preconcentrating composition may, in certain embodiments, advantageously preconcentrate a fluoroalkyl substance for detection by a sensor. In some embodiments, the preconcentrating composition is a fluorophilic composition comprising a material comprising at least one fluorine-containing moiety. In some embodiments, the material is configured to interact with a fluoroalkyl substance to form a conjugate material comprising the fluoroalkyl substance. For example, in some embodiments, the material is a polymer that is configured to interact with a fluoroalkyl substance to form a poly mer-fluoro alkyl substance conjugate. The material and / or the conjugate material comprising the fluoroalkyl substance may be at least partially soluble and / or dispersed in water. In certain embodiments, in response to a stimulus (e.g., an increase in temperature, an increase in pH), the conjugate material comprising the fluoroalkyl substance is least partially insoluble and / or precipitated in the water. For example, in response to the stimulus, the conjugate material comprising the fluoroalkyl substance may form an at least partially insoluble aggregate. In certain embodiments, the aggregate is collected on a sensor described herein. In response to a second stimulus (e.g., a decrease in temperature, a decrease in pH), the aggregate may release the fluoroalkyl substance, which may then be detected by the sensor.

[0066] According to some embodiments, methods of detecting a fluoroalkyl substance are also described. In certain embodiments, a method comprises exposing a composition, an article, and / or a sensor to a fluid suspected of comprising a fluoroalkyl substance. The fluid may comprise one or more liquids (e.g., water) and / or one or more gases. In some embodiments, the method comprises flowing the fluid over and / or through the composition, the article, and / or the sensor such that the fluid contacts the conducting material (e.g., conducting polymer). According to certain embodiments, the method comprises detecting (e.g., wirelessly detecting) an increase in conductivity in response to a presence of the fluoroalkyl substance.

[0067] According to certain embodiments, a composition is described. In some embodiments, the composition comprises a conducting material. In certain embodiments, the conducting material is or comprises a conducting polymer. FIG. 1A shows a cross-sectional schematic diagram of composition 102a comprising conducting polymer 104, in accordance with certain embodiments. As used herein, the term “conducting polymer” refers to a class of organic macromolecules comprising a 7t- conjugated backbone that enables electron delocalization and electrical conductivity when there are charge carriers present in the material. The charge carriers may be positively charged (e.g., holes) or negatively charged (e.g., electrons) depending on the characteristics of the conducting polymer. In certain embodiments, an initial state of the conducting polymer is one with few or no charge carriers and the conducting polymer is rendered conductive via activation (e.g., via a redox event), as described herein in greater detail.

[0068] The composition comprising the conducting polymer may have any of a variety of suitable forms. In some embodiments, the composition is in the form of a film (e.g., a thin film) and / or a layer. Referring, for example, to FIG. 1A, composition 102a is in the form of a film (e.g., a thin film) and / or a layer. Other forms are also possible. For example, although not shown in the figures, the composition may comprise a plurality of particles, in accordance with certain embodiments.

[0069] The conducting polymer may have any of a variety of suitable conductivities. In some embodiments, for example, the conducting polymer has a conductivity greater than or equal to 10'7S / cm, greater than or equal to 10'6S / cm, greater than or equal to 10'5S / cm, greater than or equal to 10'4S / cm, greater than or equal to 10'3S / cm, greater than or equal to 10'2S / cm, greater than or equal to 10'1S / cm, greater than or equal to 1 S / cm, greater than or equal to 10 S / cm, or greater than or equal to 102S / cm. In certain embodiments, the conducting polymer has a conductivity less than or equal to 103S / cm, less than or equal to 102S / cm, less than or equal to 10 S / cm, less than or equal to 1 S / cm, less than or equal to 10'1S / cm, less than or equal to 10'2S / cm, less than or equal to 10'3S / cm, less than or equal to 10'4S / cm, less than or equal to 10'5S / cm, less than or equal to 10'6S / cm, less than or equal to 10'7S / cm, or less. Combinations of the above recited ranges are possible (e.g., the conducting polymer has a conductivity greater than or equal to IO’7S / cm and less than or equal to 103S / cm, the conducting polymer has a conductivity greater than or equal to 10'2S / cm and less than or equal to 10'1S / cm). Other ranges are also possible.

[0070] The conductivity of the conducting polymer may be determined using a four- point probe.

[0071] The conductivity of the conducting polymer may depend on the oxidation state of the conducting polymer. According to some embodiments, for example, the conducting polymer is rendered conductive by a redox event. The base polymer may, in certain embodiments, be a conducting polymer that has a lower conductivity prior to the redox event as compared to after the redox event, in accordance with certain embodiments. In other embodiments, the base polymer may have a higher conductivity prior to the redox event as compared to after the redox event.

[0072] In certain embodiments, the conducting polymer is rendered conductive by oxidizing a base polymer. In some embodiments, for example, the conducting polymer is rendered conductive by oxidizing a base polymer with an oxidant. Suitable oxidants are described herein in greater detail. In other embodiments, the conducting polymer is rendered conductive by reducing a base polymer.

[0073] In certain embodiments, the conducting polymer is rendered conductive by a protonation event. For example, in some embodiments, the conducting polymer is rendered conductive by acid doping (e.g., introduce positive charge carriers into) a base polymer. In some embodiments, the base polymer comprises a moiety that is capable of being protonated. According to some embodiments, the moiety that is capable of being protonated is a Brpnsted base. As used herein, the term “Brpnsted base” is given its ordinary meaning in the field of chemistry and refers to a species that is capable of accepting a proton (H+). The moiety that is capable of being protonated may, in certain embodiments, be a nitrogen (N)-containing moiety. Any of a variety of suitable N- containing moieties are possible, including, for example, an aniline moiety, a pyrrole moiety, and / or combinations thereof.

[0074] According to certain embodiments, as described herein in greater detail, a fluoroalkyl analyte is configured to protonate (e.g., acid dope) the base polymer. The fluoroalkyl analyte may, in certain embodiments, be a Brpnstcd acid. As used herein, the term “Brpnsted acid” is given its ordinary meaning in the field of chemistry and refers to a species that is capable of donating a proton (H+). In some embodiments, the fluoroalkyl analyte (e.g., Brpnstcd acid) dissociates in water to provide a conjugate base of the fluoroalkyl analyte and a hydronium ion (H3<3+). In some embodiments, protonating (e.g., acid doping) the base polymer with the fluoroalkyl analyte renders the base polymer conductive and / or increases the conductivity of the base polymer.

[0075] In certain embodiments, the conducting polymer comprises at least one fluorine- containing moiety. The at least one fluorine-containing moiety of the conducting polymer may, in some embodiments, render the conducting polymer (and / or the composition comprising the conducting polymer) fluorophilic such that the conducting polymer (and / or the composition comprising the conducting polymer) has an affinity for a fluoroalkyl analyte. In some embodiments, the at least one fluorine-containing moiety is covalently attached to a backbone of the polymer, as described herein in greater detail.

[0076] As used herein, a “fluorine-containing moiety”, with respect to a composition and / or a material, refers to a portion of a molecule (e.g., a substituent, a functional group, a side chain, etc.) that includes at least one fluorine atom. The fluorine-containing moiety may be any of a variety of suitable moieties. In certain embodiments, for example, the fluorine-containing moiety is a fluoroalkyl-containing moiety, a fluoroaryl- containing moiety, a fluorinated ether-containing moiety, a fluorinated alcohol- containing moiety, a fluoroamine-containing moiety, a fluorinated heterocyclic- containing moiety, a fluoro sulfonyl-containing moiety, a fluorochloroalkyl-containing moiety, and / or combinations thereof. Other fluorine-containing moieties are also possible.

[0077] As used herein, “fluorophilic” is given its ordinary meaning in the field of chemistry and refers to the property of a material (e.g., a functional group, a molecule, etc.) that exhibits an affinity for fluorinated compounds. In certain embodiments, a fluorophilic material is soluble in, wettable by, and / or chemically compatible with a fluorinated compound and / or fluorinated media. In some embodiments, a fluorophilic material is immiscible and / or chemically incompatible with hydrocarbon compounds and / or aqueous media.

[0078] The conducting polymer may comprise fluorine in any of a variety of suitable amounts. In some embodiments, for example, the conducting polymer comprises fluorine in an amount greater than or equal to 10 weight percent (wt.%), greater than or equal to 20 wt.%, greater than or equal to 30 wt.%, greater than or equal to 40 wt.%, greater than or equal to 50 wt.%, greater than or equal to 60 wt.%, greater than or equal to 70 wt.%, or greater than or equal to 80 wt.% versus a total weight of the conducting polymer. In certain embodiments, the conducting polymer comprises fluorine in an amount less than or equal to 90 wt.%, less than or equal to 80 wt.%, less than or equal to 70 wt.%, less than or equal to 60 wt.%, less than or equal to 50 wt.%, less than or equal to 40 wt.%, less than or equal to 30 wt.%, or less than or equal to 20 wt.% versus a total weight of the conducting polymer. Combinations of the above recited ranges are also possible (e.g., the conducting polymer comprises fluorine in an amount greater than or equal to 10 wt.% and less than or equal to 90 wt.% versus a total weight of the conducting polymer, the conducting polymer comprises fluorine in an amount greater than or equal to 50 wt.% and less than or equal to 60 wt.% versus a total weight of the conducting polymer). Other ranges are also possible.

[0079] Any of a variety of suitable conducting polymers may be employed. In some embodiments, for example, the conducting polymer comprises polyaniline, polypyrrole, poly thiophene, poly arylene vinylene, poly (3, 4-ethylenedioxy thiophene), poly arylene, polyacetylene, combinations thereof, and / or fluorinated derivatives thereof. Other conducting polymers are also possible.

[0080] In certain embodiments wherein the conducting polymer comprises a fluorinated derivative of a polymer described above, the at least one fluoroalkyl group may be covalently attached to a backbone of the polymer. In certain embodiments, for example, the at least one fluoroalkyl group is covalently attached to a backbone of the polymer via an ether linkage, a thio-ether linkage, and / or a carbon linkage. Other covalent linkages between the at least one fluoroalkyl group and the backbone of the polymer are also possible.

[0081] According to certain embodiments wherein the conducting polymer comprises a fluorinated derivative of a polymer described above, the conducting polymer may be formed by polymerizing a fluorinated derivative of the monomer. In other embodiments, the conducting polymer may formed by polymerizing the monomer and fluorinating the polymer after polymerization.

[0082] The composition may comprise the conducting polymer in any of a variety of suitable amounts. In certain embodiments, for example, the composition comprises the conducting polymer in an amount greater than or equal to 10 wt.%, greater than or equal to 20 wt.%, greater than or equal to 30 wt.%, greater than or equal to 40 wt.%, greater than or equal to 50 wt.%, greater than or equal to 60 wt.%, greater than or equal to 70 wt.%, or greater than or equal to 80 wt.% versus a total weight of the composition. In some embodiments, the composition comprises the conducting polymer in an amount less than or equal to 90 wt.%, less than or equal to 80 wt.%, less than or equal to 70 wt.%, less than or equal to 60 wt.%, less than or equal to 50 wt.%, less than or equal to 40 wt.%, less than or equal to 30 wt.%, or less than or equal to 20 wt.% versus a total weight of the composition. Combinations of the above recited ranges are possible (e.g., the composition comprises the conducting polymer in an amount greater than or equal to 10 wt.% and less than or equal to 90 wt.% versus a total weight of the composition, the composition comprises the conducting polymer in an amount greater than or equal to 40 wt.% and less than or equal to 60 wt.% versus a total weight of the composition). Other ranges are also possible.

[0083] According to certain embodiments, the wt.% of the conducting polymer in the composition depends on the morphology of the composition to enable: (i) an affinity for a fluoroalkyl analyte; and (ii) a percolative conductive pathway through the composition.

[0084] In some embodiments, the composition comprises an additive. FIG. IB shows a cross-sectional schematic diagram of composition 102b comprising conducting polymer 104 and additive 106, in accordance with certain embodiments. According to some embodiments, the additive is dispersed within a matrix of the conducting polymer. Referring, for example, to FIG. IB, additive 106 may be dispersed within a matrix of conducting polymer 104. In certain embodiments, the additive interacts with the conducting polymer via non-covalent interactions and / or hydrogen -bonding interactions. The additive may, in certain embodiments, prevent aggregation of the conducting polymer.

[0085] Although not shown in FIG. IB, the conducting polymer may be coated with the additive, in accordance with certain embodiments.

[0086] In certain embodiments, the additive comprises at least one fluorine-containing moiety. The at least one fluorine-containing moiety of the additive may, in some embodiments, render the additive (and / or the composition comprising the additive) fluorophilic such that the additive (and / or the composition comprising the additive) has an affinity for a fluoroalkyl analyte. Any of a variety of suitable fluorine-containing moieties are possible, as described herein in greater detail.

[0087] The additive may comprise fluorine in any of a variety of suitable amounts. In some embodiments, for example, the additive comprises fluorine in an amount greater than or equal to 10 wt.%, greater than or equal to 20 wt.%, greater than or equal to 30 wt.%, greater than or equal to 40 wt.%, greater than or equal to 50 wt.%, greater than or equal to 60 wt.%, greater than or equal to 70 wt.%, or greater than or equal to 80 wt.% versus a total weight of the additive. In certain embodiments, the additive comprises fluorine in an amount less than or equal to 90 wt.%, less than or equal to 80 wt.%, less than or equal to 70 wt.%, less than or equal to 60 wt.%, less than or equal to 50 wt.%, less than or equal to 40 wt.%, less than or equal to 30 wt.%, or less than or equal to 20 wt.% versus a total weight of the additive. Combinations of the above recited ranges are also possible (e.g., the additive comprises fluorine in an amount greater than or equal to 10 wt.% and less than or equal to 90 wt.% versus a total weight of the additive, the additive comprises fluorine in an amount greater than or equal to 50 wt.% and less than or equal to 60 wt.% versus a total weight of the additive). Other ranges are also possible.

[0088] Any of a variety of suitable additives may be employed. In certain embodiments, the additive is a surfactant (e.g., a fluorinated surfactant). In certain embodiments, the additive comprises a polyether (e.g., a fluorinated polyether). In some embodiments, the additive comprises polyethylene glycol (PEG) (e.g., a fluorinated PEG). In some embodiments, the additive comprises a polymer (e.g., a fluorinated polymer). For example, in certain embodiments, the additive comprises a polymer with fluoroalkyl side chains. In some embodiments, the additive comprises a fluorinated polymer that is intrinsically porous. In certain embodiments, the additive comprises fluorinated aromatic groups. In some non-limiting embodiments, the additive is Krytox-PEG-600- Diamide (KPD).

[0089] In certain embodiments, the additive comprises an oxidant (e.g., a fluorinated oxidant). The oxidant may be configured to oxidize the conducting polymer to change a conductivity of the conducting polymer. Suitable oxidants include, for example, a quinone, a metal oxide, a metal halide, a metal coordination compound, and / or combinations thereof. Other oxidants are also possible. According to some embodiments, the oxidant is a pH-activated oxidant and the additive further comprises an acid (e.g., an acidic fluoroalkyl analyte). In some such embodiments, the oxidant and the acid are configured to protonate (e.g., acid dope) the conducting polymer.

[0090] According to some embodiments, the additive comprises cellulose, one or more polymers (e.g., non-conducting polymers), carbon, carbon nanotubes (e.g., single-walled carbon nanotubes), graphene, graphite, a metal, nanoparticles, combinations thereof, and / or fluorinated derivatives thereof. Other materials are also possible.

[0091] The composition may comprise the additive in any of a variety of suitable amounts. In certain embodiments, for example, the composition comprises the additive in an amount greater than or equal to 10 wt.%, greater than or equal to 20 wt.%, greater than or equal to 30 wt.%, greater than or equal to 40 wt.%, greater than or equal to 50 wt.%, greater than or equal to 60 wt.%, greater than or equal to 70 wt.%, or greater than or equal to 80 wt.% versus a total weight of the composition. In some embodiments, the composition comprises the additive in an amount less than or equal to 90 wt.%, less than or equal to 80 wt.%, less than or equal to 70 wt.%, less than or equal to 60 wt.%, less than or equal to 50 wt.%, less than or equal to 40 wt.%, less than or equal to 30 wt.%, or less than or equal to 20 wt.% versus a total weight of the composition. Combinations of the above recited ranges are possible (e.g., the composition comprises the additive in an amount greater than or equal to 10 wt.% and less than or equal to 90 wt.% versus a total weight of the composition, the composition comprises the additive in an amount greater than or equal to 40 wt.% and less than or equal to 60 wt.% versus a total weight of the composition). Other ranges are also possible.

[0092] In certain embodiments, the conducting polymer is part of a composite structure. In certain embodiments, for example, the composition comprises a composite structure comprising the conducting polymer and one or more additional components. FIG. 1C shows a cross-sectional schematic diagram of composition 102c comprising composite structure 108 comprising conducting polymer 104 and additional component 110. In certain embodiments, the composite structure is a layered structure comprising a layer of the conducting polymer and a layer of the one more additional components deposited on the layer of the conducting polymer. Referring, for example, to FIG. 1C, composite structure 108 is a layered structure comprising a layer of conducting polymer 104 and a layer of additional component 110 deposited on the layer of conducting polymer 104. In some embodiments, for example, the layer of the one or more additional components is coated on the layer of the conducting polymer.

[0093] Although not shown in FIG. 1C, the composite structure may comprise any of a variety of suitable structures, including, for example, a single dispersion of the conducting polymer and a single dispersion of the one or more additional components.

[0094] Although not shown in FIG. 1C, the composite structure may comprise an additive. In certain embodiments, for example, the layer of conducting polymer and / or the layer of the one or more additional components comprises an additive (e.g., dispersed within a matrix of the conducting polymer and / or the one or more additional components). Suitable additives are described herein in greater detail. In certain embodiments, the one or more additional components comprise a conducting material. For example, the one or more additional components may, in some embodiments, comprise a material having a conductivity greater than or equal to 10'7S / cm and less than or equal to 103S / cm.

[0095] In some embodiments, the one or more additional components comprise at least one fluorine-containing moiety. The at least one fluorine-containing moiety of the one or more additional components may, in some embodiments, render the one or more additional components (and / or the composite structure comprising the one or more additional components) fluorophilic such that the one or more additional components (and / or the composite structure comprising the one or more additional components) has an affinity for a fluoroalkyl analyte. Any of a variety of suitable fluorine-containing moieties are possible, as described herein in greater detail.

[0096] The one or more additional components may comprise fluorine in any of a variety of suitable amounts. In certain embodiments, for example, the one or more additional components comprise fluorine in an amount greater than or equal to 10 wt.%, greater than or equal to 20 wt.%, greater than or equal to 30 wt.%, greater than or equal to 40 wt.%, greater than or equal to 50 wt.%, greater than or equal to 60 wt.%, greater than or equal to 70 wt.%, or greater than or equal to 80 wt.% versus a total weight of the one or more additional components. In certain embodiments, the one or more additional components comprise fluorine in an amount less than or equal to 90 wt.%, less than or equal to 80 wt.%, less than or equal to 70 wt.%, less than or equal to 60 wt.%, less than or equal to 50 wt.%, less than or equal to 40 wt.%, less than or equal to 30 wt.%, or less than or equal to 20 wt.% versus a total weight of the one or more additional components. Combinations of the above recited ranges are also possible (e.g., the one or more additional components comprise fluorine in an amount greater than or equal to 10 wt.% and less than or equal to 90 wt.% versus a total weight of the one or more additional components, the one or more additional components comprise fluorine in an amount greater than or equal to 50 wt.% and less than or equal to 60 wt.% versus a total weight of the one or more additional components). Other ranges are also possible.

[0097] The composite structure may comprise any of a variety of suitable additional components. In some embodiments, the composite structure comprises cellulose, one or more polymers (e.g., non-conducting polymers), carbon, carbon nanotubes (e.g., single- walled carbon nanotubes), graphene, graphite, a metal, nanoparticles, combinations thereof, and / or fluorinated derivatives thereof. Other materials are also possible.

[0098] In certain embodiments, the composite structure comprises a surfactant (e.g., a fluorinated surfactant). In certain embodiments, the composite structure comprises a poly ether (e.g., a fluorinated poly ether). In some embodiments, the composite structure comprises polyethylene glycol (PEG) (e.g., a fluorinated PEG). In some embodiments, the composite structure comprises a polymer (e.g., a fluorinated polymer). For example, in certain embodiments, the composite structure comprises a polymer with fluoroalkyl side chains. In some embodiments, the composite structure comprises a fluorinated polymer that is intrinsically porous. In certain embodiments, the composite structure comprises fluorinated aromatic groups. In some non-limiting embodiments, the composite structure comprises Krytox-PEG-600-Diamide (KPD).

[0099] In certain embodiments, the composite structure comprises an oxidant (e.g., a fluorinated oxidant). The oxidant may, in some embodiments, be configured to oxidize the conducting polymer to change a conductivity of the conducting polymer. Suitable oxidants include, for example, a quinone, a metal oxide, a metal halide, a metal coordination compound, and / or combinations thereof. Other oxidants are also possible. According to some embodiments, the oxidant is a pH-activated oxidant and the composite structure further comprises an acid (e.g., an acidic fluoroalkyl analyte). In some such embodiments, the oxidant and the acid are configured to protonate (e.g., acid dope) the conducting polymer.

[0100] The composition may comprise the one or more additional components in any of a variety of suitable amounts. In certain embodiments, for example, the composition comprises the one or more additional components in an amount greater than or equal to 2 wt.%, greater than or equal to 5 wt.%, greater than or equal to 10 wt.%, greater than or equal to 15 wt.%, greater than or equal to 20 wt.%, greater than or equal to 30 wt.%, or greater than or equal to 40 wt.% versus a total weight of the composition. In some embodiments, the composition comprises the one or more additional components in an amount less than or equal to 50 wt.%, less than or equal to 40 wt.%, less than or equal to 30 wt.%, less than or equal to 20 wt.%, less than or equal to 15 wt.%, less than or equal to 10 wt.%, or less than or equal to 5 wt.% versus a total weight of the composition. Combinations of the above recited ranges are possible (e.g., the composition comprises the one or more additional components in an amount greater than or equal to 2 wt.% and less than or equal to 50 wt.% versus a total weight of the composition, the composition comprises the one or more additional components in an amount greater than or equal to 15 wt.% and less than or equal to 20 wt.% versus a total weight of the composition). Other ranges are also possible.

[0101] In accordance with certain embodiments, the composition is configured such that the composition comprises a conducting material (e.g., a conducting polymer) and at least one component that comprises at least one fluorine-containing moiety (which may, but need not, be the conducting material). In certain embodiments, the composition comprises a conducting polymer comprising at least one fluorine-containing moiety. Referring, for example, to FIG. 1A, composition 102a may comprise conducting polymer 104 comprising at least one fluorine-containing moiety. In some embodiments, the composition comprises a conducting polymer comprising at least one fluorine-containing moiety and an additive (e.g., a non-fluorinated additive). For example, referring to FIG. IB, composition 102b may comprise conducting polymer 104 comprising at least one fluorine-containing moiety and additive 106 (e.g., a non-fluorinated additive). In other embodiments, the composition comprises a conducting polymer (e.g., a non-fluorinated conducting polymer) and an additive comprising at least one fluorine-containing moiety. For example, referring to FIG. IB, composition 102b may comprise conducting polymer 104 (e.g., a non-fluorinated conducting polymer) and additive 106 comprising at least one fluorine-containing moiety. In yet other embodiments, the composition comprises a conducting polymer comprising at least one fluorine-containing moiety and an additive comprising at least one fluorine-containing moiety. Referring, for example, to FIG. IB, composition 102b may comprise conducting polymer 104 comprising at least one fluorine-containing moiety and additive 106 comprising at least one fluorine-containing moiety.

[0102] In some embodiments, the composition comprises a composite structure comprising: (i) a conducting polymer comprising at least one fluorine-containing moiety; and (ii) one or more additional components (e.g., one or more non-fluorinated additional components). Referring, for example, to FIG. 1C, composition 102c may comprise composite structure 108 comprising: (i) conducting polymer 104 comprising at least one fluorine-containing moiety; and (ii) additional component 110 (e.g., a non-fluorinated additional component). In other embodiments, the composition comprises a composite structure comprising: (i) a conducting polymer (e.g., a non-fluorinated conducting polymer); and (ii) one or more additional components comprising at least one fluorine- containing moiety. For example, referring to FIG. 1C, composition 102c may comprise composite structure 108 comprising: (i) conducting polymer 104 (e.g., a non-fluorinated conducting polymer); and (ii) additional component 110 comprising at least one fluorine- containing moiety. In yet other embodiments, the composition comprises a composite structure comprising: (i) a conducting polymer comprising at least one fluorine- containing moiety; and (ii) one or more additional components comprising at least one fluorine-containing moiety. Referring, for example, to FIG. 1C, composition 102c may comprise composite structure 108 comprising: (i) conducting polymer 104 comprising at least one fluorine-containing moiety; and (ii) additional component 110 comprising at least one fluorine-containing moiety.

[0103] As described herein in greater detail, the composition comprising at least one fluorine-containing moiety may be fluorophilic, in accordance with certain embodiments. In some embodiments, for example, the composition has an affinity for a fluoroalkyl analyte.

[0104] The composition may comprise fluorine in any of a variety of suitable amounts. In some embodiments, the composition comprises fluorine in an amount greater than or equal to 10 wt.%, greater than or equal to 20 wt.%, greater than or equal to 30 wt.%, greater than or equal to 40 wt.%, greater than or equal to 50 wt.%, greater than or equal to 60 wt.%, greater than or equal to 70 wt.%, or greater than or equal to 80 wt.% versus a total weight of the composition. In some embodiments, the composition comprises fluorine in an amount less than or equal 90 wt.%, less than or equal to 80 wt.%, less than or equal to 70 wt.%, less than or equal to 60 wt.%, less than or equal to 50 wt.%, less than or equal to 40 wt.%, less than or equal to 30 wt.%, or less than or equal to 20 wt.% versus a total weight of the composition. Combinations of the above recited ranges are possible (e.g., the composition comprises fluorine an amount greater than or equal to 10 wt.% and less than or equal to 90 wt.% versus a total weight of the composition, the composition comprises fluorine an amount greater than or equal to 50 wt.% and less than or equal to 60 wt.% versus a total weight of the composition). Other ranges are also possible. In certain embodiments, the composition is configured to interact with a fluoroalkyl analyte. For example, in some embodiments, the composition is configured to absorb a fluoroalkyl analyte. In certain embodiments, the conducting polymer (and / or the composite structure comprising the conducting polymer) is configured to absorb the fluoroalkyl analyte. In some embodiments, the additive is configured to absorb the fluoroalkyl analyte. According to some embodiments, both the conducting polymer (and / or the composite structure comprising the conducting polymer) and the additive are configured to absorb the fluoroalkyl analyte.

[0105] The composition may interact with (e.g., absorb) a fluoroalkyl analyte via any of a variety of suitable mechanisms. In certain embodiments, the composition is configured to interact with (e.g., absorb) the fluoroalkyl analyte via a redox event. According to some embodiments, for example, the fluoroalkyl analyte is configured to cause a reaction that results in an oxidation of the composition (e.g., conducting polymer). For example, as described herein in greater detail, the fluoroalkyl analyte is configured to introduce charge carriers in the conducting material by donating a positive charge (e.g., H+) to the conducting material. In other embodiments, the fluoroalkyl analyte is configured to cause a reaction that results in a reduction of the composition (e.g., conducting polymer).

[0106] In some embodiments, the conducting polymer is configured to absorb the fluoroalkyl analyte more strongly at a first level of oxidation (e.g., a first oxidation state) and less strongly at a second level of oxidation (e.g., a second oxidation state). The first level of oxidation may, in some embodiments, be a lower oxidation state than the second level of oxidation. In other embodiments, the first level of oxidation is a higher oxidation state than the second level of oxidation.

[0107] According to certain embodiments, the composition is configured such that the composition displays an increase in conductivity in response to a presence of a fluoroalkyl analyte. For example, in some embodiments, the composition is configured to interact with (e.g., absorb) the fluoroalkyl analyte, which increases the conductivity of the composition (e.g., the conducting polymer). In some embodiments, the fluoroalkyl analyte donates a charge (e.g., a positive charge, such as H+) to the conducting material, thereby resulting in an increase in charge carrier concentration of the conducting material, an increase in the electrical conductivity of the conducting material, and a decrease in the electrical resistivity of the conducting material. According to some embodiments, the fluoroalkyl analyte removes electron density from the conducting material, thereby resulting in the formation of holes (i.e., positive charge carriers).

[0108] In certain embodiments, the fluoroalkyl analyte is configured to protonate (e.g., acid dope) the conducting polymer. For example, as described herein, the conducting polymer may comprise a moiety that is capable of being protonated, such as a Brpnstcd base, and the fluoroalkyl analyte may comprise a Brpnstcd acid. The fluoroalkyl analyte may protonate the moiety that is capable of being protonated, thereby increasing the conductivity of the composition (e.g., conducting polymer).

[0109] The increase in conductivity may be any of a variety of suitable increases. In some embodiments, for example, the increase in conductivity is an increase by a factor of at least 10, at least 50, at least 100, at least 500, at least 1,000, at least 5,000, at least 10,000, or at least 50,000. In some embodiments, the increase in conductivity is an increase by a factor of less than or equal to 100,000, less than or equal to 50,000, less than or equal to 10,000, less than or equal to 5,000, less than or equal to 1,000, less than or equal to 500, less than or equal to 100, or less than or equal to 50. Combinations of the above recited ranges are possible (e.g., the increase in conductivity is an increase by a factor of at least 10 and less than or equal to 100,000). Other ranges are also possible.

[0110] In some embodiments, the composition is configured such that the composition displays a decrease in conductivity in response to a presence of a fluoroalkyl analyte. In certain embodiments, for example, the composition is configured to interact with (e.g., absorb) the fluoroalkyl analyte, which decreases the conductivity of the composition (e.g., the conducting polymer). In certain embodiments, the fluoroalkyl substance is configured to decrease the charge carrier concentration of the conducting material, thereby resulting in a decrease in the electrical conductivity of the conducting material and an increase in the electrical resistivity of the conducting material.

[0111] The decrease in conductivity may be any of a variety of suitable increases. In some embodiments, for example, the decrease in conductivity is a decrease by a factor of at least 10, at least 50, at least 100, at least 500, at least 1,000, at least 5,000, at least 10,000, or at least 50,000. In some embodiments, the decrease in conductivity is a decrease by a factor of less than or equal to 100,000, less than or equal to 50,000, less than or equal to 10,000, less than or equal to 5,000, less than or equal to 1,000, less than or equal to 500, less than or equal to 100, or less than or equal to 50. Combinations of the above recited ranges are possible (e.g., the decrease in conductivity is a decrease by a factor of at least 10 and less than or equal to 100,000). Other ranges are also possible.

[0112] According to some embodiments, the composition is hydrophobic. The composition may have any of a variety of suitable water contact angles. In certain embodiments, for example, the composition has a water contact angle greater than or equal to 90°, greater than or equal to 120°, or greater than or equal to 150°. In some embodiments, the composition has a water contact angle less than or equal to 180°, less than or equal to 150°, or less than or equal to 120°. Combinations of the above recited ranges are possible (e.g., the composition has a water contact angle greater than or equal to 90° and less than or equal to 180°, the composition has a water contact angle greater than 120° or equal to and less than or equal to 150°). Other ranges are also possible.

[0113] According to some embodiments, an article is described. In certain embodiments, the article comprises a composition (e.g., as described herein in greater detail). In some embodiments, the composition is deposited on at least a portion of a substrate. FIG. 2A shows a cross-sectional schematic diagram of article 202a comprising composition 102a shown in FIG. 1A deposited on at least a portion of substrate 212, in accordance with certain embodiments. FIG. 2B shows a cross-sectional schematic diagram of article 202b comprising composition 102b shown in FIG. IB deposited on at least a portion of substrate 212, in accordance with certain embodiments. FIG. 2C shows a cross-sectional schematic diagram of article 202c comprising composition 102c shown in FIG. 1C deposited on at least a portion of substrate 212, in accordance with certain embodiments. In certain embodiments, the composition (e.g., composition 102a, 102b, and / or 102c) is coated on a surface of the substrate (e.g., substrate 212).

[0114] The composition (e.g., composition 102a, 102b, and / or 102c) may be deposited on at least the portion of the substrate (e.g., substrate 212) via any of a variety of suitable mechanisms. In certain embodiments, for example, the composition is deposited on at least the portion of the substrate by dip coating, spray coating, blade coating, silk screening, painting, vapor deposition, inkjet printing, extrusion, fiber spinning, electrospinning, abrasion, and / or combinations thereof. Other deposition mechanisms are also possible. In certain embodiments, a solvent used to deposit the composition comprises at least one fluorine-containing moiety. Suitable deposition solvents include, for example, hexafluoro-isopropanol. Other deposition solvents are also possible (e.g., aromatics, ethers, halogenated hydrocarbons). In certain embodiments, the conducting polymer is formed on the substrate by polymerizing a monomer precursor on the substrate.

[0115] According to some embodiments, the conducting polymer and the additive are mixed and deposited on the substrate. In other embodiments, the additive is applied to the conducting polymer after depositing the conducting polymer on the substrate.

[0116] In certain embodiments, the article is produced by successive deposition of the conducting polymer and the one or more additives and / or additional materials. For example, in accordance with some embodiments, multiple passes with an inkjet printer may be used to produce a material that has different configurations of the conducting polymer and the one or more additives and / or additional materials. In some embodiments, printing comprises printing the conducting polymer followed by printing the one or more additives and / or additional materials. In other embodiments, printing comprises printing the one or more additives and / or additional materials followed by printing the conducting polymer. Printing may include small offsets, in accordance with certain embodiments. Other deposition methods, fabrication methods, and final structures are also possible.

[0117] The substrate (e.g., substrate 212) may comprise any of a variety of suitable materials. In certain embodiments, for example, the substrate comprises paper, a polymer, skin (e.g., human skin), a textile, a ceramic, a plant, wood, cellulose (e.g., nitrocellulose) glass, silicon (Si), silicon dioxide (SiO2), alumina (AI2O3), a metal, and / or combinations thereof. Other substrate materials are also possible.

[0118] In certain embodiments, the article is a lateral flow assay device. For example, referring to FIGS. 2A-2C, article 202 (e.g., article 202a, 202b, and / or 202c) may be a lateral flow assay device. The lateral flow assay device may be configured to wick a fluid (e.g., a solution) into the lateral flow assay device via capillary forces, in accordance with certain embodiments.

[0119] In some embodiments, the article is a membrane and / or a filter. Referring, for example, to FIGS. 2A-2B, article 202 (e.g., article 202a, 202b, and / or 202c) may be a membrane and / or filter. In some embodiments, the membrane and / or the filter is at least partially porous, in some embodiments, such that a fluid (e.g., a liquid and / or a gas) may be passed through the membrane and / or the filter (e.g., via a vertical flow assay). In certain embodiments, the composition is coated on a surface of the membrane and / or the filter such that the composition allows the fluid to pass through the membrane and / or the filter. The membrane and / or the filter may, in certain embodiments, be patterned with multiple materials.

[0120] According to some embodiments, the article is tubing. Referring, for example, to FIGS. 2A-2B, article 202 (e.g., article 202a, 202b, and / or 202c) may be tubing. In certain embodiments, the composition is coated on an inner surface of the tubing.

[0121] As described herein in greater detail, an article may be configured as a sensor, in accordance with certain embodiments.

[0122] In certain embodiments, a sensor is described. According to some embodiments, a sensor is configured to detect a fluoroalkyl substance (e.g., a fluoroalkyl analyte). FIG. 3A shows a cross-sectional schematic diagram of sensor 302a comprising conducting material 304, in accordance with certain embodiments. The conducting material may comprise a conducting polymer (e.g., as described herein in greater detail), in accordance with certain embodiments. In some embodiments, the conducting material (e.g., conducting polymer) comprises at least one fluorine-containing moiety. For example, referring to FIG. 3A, conducting material 304 comprises at least one fluorine-containing moiety.

[0123] The conducting material may, in certain embodiments, comprise a carbon-based material. In certain embodiments, for example, the conducting material comprises carbon nanotubes (e.g., single-walled carbon nanotubes), graphite, graphene, carbon black, and / or combinations thereof. In certain embodiments, the conducting material comprises a metal chalcogenide. The carbon-based material and / or the metal chalcogenide may be covalently and / or non-covalently functionalized with at least one fluorine-containing moiety, in accordance with certain embodiments.

[0124] According to some embodiments, the sensor comprises a conducting material and an additive (e.g., as described herein in greater detail). FIG. 3B shows a cross-sectional schematic diagram of sensor 302b comprising conducting material 304 and additive 106, in accordance with certain embodiments. According to some embodiments, the additive is dispersed within a matrix of the conducting material. For example, referring to FIG. 3B, additive 106 may be dispersed within a matrix of conducting material 304. In certain embodiments, the additive comprises at least one fluorine-containing moiety. For example, referring to FIG. 3B, additive 106 may comprise at least one fluorine- containing moiety.

[0125] In certain embodiments, the sensor comprises a composite structure comprising a conducting material and one or more additional components (e.g., as described herein in greater detail). FIG. 3C shows a cross-sectional schematic diagram of sensor 302c comprising composite structure 108 comprising conducting material 304 and additional component 110, in accordance with certain embodiments. In some embodiments, the composite structure is a layered structure comprising a layer of the conducting material and a layer of the one more additional components deposited on the layer of the conducting material. Referring, for example, to FIG. 3C, composite structure 108 is a layered structure comprising a layer of conducting material 304c and a layer of additional component 110 deposited on the layer of conducting material 304c. In some embodiments, the one or more additional components comprise at least one fluorine- containing moiety. For example, referring to FIG. 3C, additional component 110 may comprises at least one fluorine-containing moiety.

[0126] Although not shown in FIG. 3C, the composite structure may comprise an additive. In certain embodiments, for example, the layer of conducting material and / or the layer of the one or more additional components comprises an additive (e.g., dispersed within a matrix of the conducting material and / or the one or more additional components).

[0127] According to certain embodiments, the sensor (e.g., sensor 302a, 302b, and / or 302c) may be configured as a lateral flow assay device.

[0128] In some embodiments, the sensor is configured such that the sensor comprises a conducting material and at least one component that comprises at least one fluorine- containing moiety (which may, but need not, be the conducting material). In certain embodiments, the sensor comprises a conducting material comprising at least one fluorine-containing moiety. For example, referring to FIG. 3A, sensor 302a may comprise conducting material 304 (e.g., conducting polymer) comprising at least one fluorine-containing moiety. In some embodiments, the sensor comprises a conducting polymer comprising at least one fluorine-containing moiety and an additive (e.g., a nonfluorinated additive). For example, referring to FIG. 3B, sensor 302b may comprise conducting material 304 (e.g., conducting polymer) comprising at least one fluorine- containing moiety and additive 106 (e.g., a non-fluorinated additive). In other embodiments, the sensor comprises a conducting material (e.g., a non-fluorinated conducting polymer) and an additive that comprises at least one fluorine-containing moiety. Referring, for example, to FIG. 3B, sensor 302b comprises conducting material 304 (e.g., a non-fluorinated conducting polymer) and additive 106 comprising at least one fluorine-containing moiety. In yet other embodiments, the sensor comprises a conducting polymer comprising at least one fluorine-containing moiety and an additive comprising at least one fluorine-containing moiety. For example, referring to FIG. 3B, sensor 302b comprises conducting material 304 (e.g., a conducting polymer) comprising at least one fluorine-containing moiety and additive 106 comprising at least one fluorine- containing moiety.

[0129] In some embodiments, the sensor comprises a composite structure comprising: (i) a conducting material comprising at least one fluorine-containing moiety; and (ii) one or more additional components (e.g., one or more non-fluorinated additional components). Referring, for example, to FIG. 3C, sensor 302c may comprise composite structure 108 comprising: (i) conducting material 304 comprising at least one fluorine-containing moiety; and (ii) additional component 110 (e.g., a non-fluorinated additional component). In other embodiments, the sensor comprises a composite structure comprising: (i) a conducting material (e.g., a non-fluorinated conducting material); and (ii) one or more additional components comprising at least one fluorine-containing moiety. For example, referring to FIG. 3C, sensor 302c may comprise composite structure 108 comprising: (i) conducting material 304 (e.g., a non-fluorinated conducting material); and (ii) additional component 110 comprising at least one fluoroalkyl group. In yet other embodiments, the sensor comprises a composite structure comprising: (i) a conducting material comprising at least one fluorine-containing moiety; and (ii) one or more additional components comprising at least one fluorine-containing moiety. Referring, for example, to FIG. 3C, sensor 302c may comprise composite structure 108 comprising: (i) conducting material 304 comprising at least one fluorine-containing moiety; and (ii) additional component 110 comprising at least one fluorine-containing moiety.

[0130] The conducting material (and / or the composite structure comprising the conducting material) may be deposited on at least a portion of a substrate. Referring, for - 1 - example, to FIGS. 3A-3B, conducting material 304 (and / or composite structure 108 comprising conducting material 304) is deposited on at least a portion of substrate 212. In certain embodiments, the conducting material (e.g., conducting material 304) is coated a surface of the substrate (e.g., substrate 212).

[0131] The conducting material (and / or the composite structure comprising the conducting material) may be deposited on at least the portion of the substrate (e.g., substrate 212) via any of a variety of suitable mechanisms. In certain embodiments, for example, the conducting material (and / or the composite structure comprising the conducting material) is deposited on at least the portion of the substrate by dip coating, spray coating, blade coating, silk screening, painting, vapor deposition, ink jet printing, extrusion, fiber spinning, electrospinning, abrasion, and / or combinations thereof. Other deposition mechanisms are also possible, as described herein in greater detail with respect to the conducting polymer. In certain embodiments, a solvent used to deposit the conducting material comprises at least one fluorine-containing moiety. Suitable deposition solvents include, for example, hexafluoro-isopropanol. Other deposition solvents are also possible (e.g., aromatics, ethers, halogenated hydrocarbons).

[0132] The substrate may comprise any of a variety of suitable materials, including those described herein with respect to FIG. IB.

[0133] Although not shown in the figures, the sensor may comprise one or more electrodes. According to certain embodiments, the conducting material (e.g., conducting polymer) is in electrical communication with the one or more electrodes. In some embodiments, for example, the conducting material (e.g., conducting polymer) is in direct contact with the one or more electrodes.

[0134] The one or more electrodes may comprise any of a variety of suitable materials. In some embodiments, for example, the one or more electrodes comprise a metal (e.g., gold, platinum, aluminum), carbon, and / or combinations thereof. Other electrode materials are also possible. In some embodiments, the one or more electrodes are interdigitated electrodes (IDEs).

[0135] According to certain embodiments, the sensor is fabricated by depositing the one or more electrodes on a surface of the substrate and depositing the conducting material (and / or the composite structure comprising the conducting material) on the surface of the substrate such that the conducting material is in electrical communication with the one or more electrodes. In some embodiments, depositing the one or more electrodes on the surface of the substrate comprises dip coating, spray coating, blade coating, silk screening, painting, vapor deposition, inkjet printing, extrusion, fiber spinning, electrospinning, abrasion, and / or combinations thereof. Other deposition mechanisms are also possible.

[0136] The article (e.g., sensor) may comprise (and / or be in wired and / or wireless communication with) one or more additional components not shown in the figures. For example, in some embodiments, the article comprises (and / or is in wired and / or wireless communication with) circuitry and / or electronics for signal readout, output, and / or conditioning, such as one or more multiplexers, analog-to-digital converters, bridge circuits, and / or microcontrollers. In some embodiments, the article comprises (and / or is in wired and / or wireless electrical communication with) one or more detectors and / or readers, which may be coupled to the circuitry and / or electronics. In certain embodiments, the article comprises (and / or is in wired and / or wireless electrical communication with) one or more data acquisition and / or processing units, which may be coupled to the circuitry and / or electronics. In some embodiments, the one or more data acquisition and / or processing units may be configured to receive a signal, readout, and / or output from the article and execute data processing of the signal, readout, and / or output based on instructions (e.g., memory storing instructions).

[0137] According to certain embodiments, the article (e.g., sensor) may be housed in a housing and / or package that allows controlled exposure to a fluid (e.g., a fluid suspected of containing a fluoroalkyl analyte), while advantageously protecting the components of the article (e.g., the conducting material and one or more additional components, such as one or more electrodes, circuitry, and / or electronics). In some embodiments, the article (and / or the housing and / or package housing the article) comprises one or more fluid flow controllers, (pre)concentrators, membranes, filters, pH sensors, temperature sensors, and / or humidity sensors.

[0138] In some embodiments, the sensor is configured such that the sensor displays a change in conductivity in response to a presence of a fluoroalkyl analyte. According to certain embodiments, the change in conductivity in response to the presence of the fluoroalkyl analyte is an increase in conductivity. In some embodiments, for example, the fluoroalkyl analyte donates a charge (e.g., a positive charge, such as H+) to the conducting material, thereby resulting in an increase in charge carrier concentration of the conducting material, an increase in the electrical conductivity of the conducting material, and a decrease in the electrical resistivity of the conducting material.

[0139] According to some embodiments, the change in conductivity in response to the presence of the fluoroalkyl analyte is a decrease in conductivity. In certain embodiments, for example, the fluoroalkyl analyte decreases a charge carrier concentration of the conducting material, thereby resulting in a decrease in the electrical conductivity of the conducting material and an increase in the electrical resistivity of the conducting material.

[0140] In certain embodiments, as the electrical conductivity and / or electrical resistivity of the conducting material changes, a resulting signal (e.g., electrical signal) may be detected, transmitted, and / or processed, as described herein in greater detail.

[0141] According to certain embodiments, the change in conductivity in response to the presence of the fluoroalkyl analyte is reversible. For example, in some embodiments, the conducting material has a first conductivity in the absence of the fluoroalkyl analyte and a second conductivity in the presence of the fluoroalkyl analyte. In certain embodiments, after removing the conducting material from the presence of the fluoroalkyl analyte, the conductivity of the conducting material may return to the first conductivity.

[0142] According to certain embodiments, the article (e.g., sensor) is configured such that the article is powered wirelessly. For example, in some embodiments, the change (e.g., increase) in conductivity and / or the change (e.g., decrease) in resistivity of the conducting material in response to the presence of a fluoroalkyl analyte is a signal (e.g., electrical signal) that is determined wirelessly. As described above, for example, the electrical conductivity of the conducting material may increase and / or the electrical resistivity of the conducting material may decrease in response to the presence of the fluoroalkyl analyte, and a resulting signal (e.g., electrical signal) may be detected, transmitted, and / or processed wirelessly. In certain embodiments, the increase in conductivity and / or the decrease in resistivity of the conducting material in response to the presence of a fluoroalkyl analyte is a signal (e.g., electrical signal) that is determined wirelessly by a smartphone.

[0143] According to some embodiments, the article (e.g., sensor) comprises at least one resonant radio frequency circuit. In certain embodiments, for example, the article comprises a passive radio-frequency identification (RFID) device. The RFID device may, in certain embodiments, be configured to transmit a signal (e.g., an electrical signal, such a change in conductivity and / or a change in resistivity of the conducting material in response to the presence of a fluoroalkyl analyte) when scanned by a reader (e.g., a smartphone, as described above). In certain embodiments, the article (e.g., sensor) comprises a wireless transmitter. The wireless transmitter may, in certain embodiments, be configured to transmit a signal (e.g., an electrical signal, such as a change in conductivity and / or a change in resistivity of the conducting material in response to the presence of a fluoroalkyl analyte) to a reader (e.g., a smartphone, as described above) using technologies such as Wi-Fi and / or Bluetooth. The article may be configured to switch between RFID and wireless transmitter transmission modes, in accordance with certain embodiments.

[0144] The articles (e.g., sensors) described herein may be implemented in any of a variety of suitable applications, including, for example, filtration systems and / or chemical reactors (e.g., flow based chemical reactors). In certain embodiments, the articles described herein are hand-held devices used for portable applications (e.g., field testing). Other applications are also possible.

[0145] Systems for detecting a fluoroalkyl substance (e.g., a fluoroalkyl analyte) are also described. In some embodiments, a system comprises an article (e.g., sensor) as described in greater detail herein. The article may be fluidically connected to one or more reservoirs and / or sources of a fluid. In certain embodiments, the article and / or the one or more reservoirs and / or sources of the fluid may be fluidically connected to one or more pumps (e.g., recirculating pumps), fans, and / or gravity feeds configured to facilitate flow (e.g., continuous flow) of a fluid from the one or more reservoirs and / or sources of the fluid to the article.

[0146] In certain embodiments, a method of detecting a fluoroalkyl analyte (e.g., a fluoroalkyl analyte) is described. In some embodiments, the method comprises exposing a composition (e.g., as described in greater detail herein), an article (e.g., as described in greater detail herein), and / or a sensor (e.g., as described in greater detail herein) to a fluid suspected of comprising the fluoroalkyl analyte.

[0147] In certain embodiments, exposing the composition, the article, and / or the sensor to the fluid comprises exposing the conducting material to the fluid. In some embodiments, exposing the conducting material to the fluid comprises flowing the fluid over and / or through the composition, the article, and / or the sensor such that the fluid contacts the conducting material.

[0148] According to some embodiments, the method comprises detecting an increase in conductivity in response to the presence of the fluoroalkyl analyte. In certain embodiments, for example, as described herein in greater detail, a conducting material may be configured to interact with (e.g., absorb) the fluoroalkyl analyte. In certain embodiments, the fluoroalkyl analyte may donate a charge to the conducting material, thereby resulting in an increase in charge carrier concentration of the conducting material, an increase in the electrical conductivity of the conducting material, and a decrease in the electrical resistivity of the conducting material.

[0149] In certain embodiments, the method comprises detecting a decrease in conductivity in response to the presence of the fluoroalkyl analyte. In certain embodiments, for example, as described herein in greater detail, a conducting material may be configured to interact with (e.g., absorb) the fluoroalkyl analyte. In certain embodiments, the fluoroalkyl analyte decreases a charge carrier concentration of the conducting material, thereby resulting in a decrease in the electrical conductivity of the conducting material, and an increase in the electrical resistivity of the conducting material.

[0150] In some embodiments, detecting the increase and / or the decrease in conductivity in response to the presence of the fluoroalkyl analyte comprises detecting an electrical signal, transmitting the electrical signal, and / or processing the electrical signal, as described herein in greater detail.

[0151] In some embodiments, the detecting is performed continuously as the conducting material is exposed to the fluid. In other embodiments, the detecting is performed after the conducting material is exposed to the fluid. In certain embodiments wherein the fluid comprises a solution, the conducting material is dried before performing the detecting. In some embodiments, the conducting material is dried by heating the conducting material.

[0152] The composition, the article, and / or the sensor may capable of detecting a fluoroalkyl analyte at any of a variety of suitable limits of detection. In certain embodiments, for example, the composition, the article, and / or the sensor is capable of detecting a fluoroalkyl analyte at a parts per billion (ppb) level. In certain embodiments, the composition, the article, and / or the sensor is capable of detecting the fluoroalkyl analyte at a parts per trillion (ppt) level. In some embodiments, for example, the composition, the article, and / or the sensor is capable of detecting the fluoroalkyl analyte at a sensitivity less than or equal to 1000 ppt, less than or equal to 900 ppt, less than or equal to 800 ppt, less than or equal to 700 ppt, less than or equal to 600 ppt, less than or equal to 500 ppt, less than or equal to 400 ppt, less than or equal to 300 ppt, less than or equal to 200 ppt, less than or equal to 100 ppt, less than or equal to 50 ppt, or less than or equal to 10 ppt. In certain embodiments, the composition, the article, and / or the sensor is capable of detecting the fluoroalkyl analyte at a sensitivity greater than or equal to 1 ppt, greater than or equal to 10 ppt, greater than or equal to 50 ppt, greater than or equal to 100 ppt, greater than or equal to 200 ppt, greater than or equal to 300 ppt, greater than or equal to 400 ppt, greater than or equal to 500 ppt, greater than or equal to 600 ppt, greater than or equal to 700 ppt, greater than or equal to 800 ppt, or greater than or equal to 900 ppt. Combinations of the above recited ranges are possible (e.g., the composition, the article, and / or the sensor is capable of detecting the fluoroalkyl analyte at a sensitivity less than or equal to 1000 ppt and greater than or equal to 1 ppt, the composition, the article, and / or the sensor is capable of detecting the fluoroalkyl analyte at a sensitivity less than or equal to 500 ppt and greater than or equal to 400 ppt). Other ranges are also possible.

[0153] According to certain embodiments, a composition comprising a material comprising at least one fluorine-containing moiety is described. FIG. 4 shows a cross- sectional schematic diagram of composition 102d comprising material 404 comprising at least one fluorine-containing moiety, in accordance with certain embodiments.

[0154] The composition comprising the material comprising at least one fluorine- containing moiety may have any of a variety of suitable forms. In some embodiments, the composition comprises a plurality of particles. Referring, for example, to FIG. 4, composition 102d may comprise a plurality of particles 406 (e.g., 406a-406d). The particles may, in certain embodiments, comprise nanoparticles, microparticles, and / or combinations thereof.

[0155] The at least one fluorine-containing moiety of the material may, in some embodiments, render the material (and / or the composition comprising the material) fluorophilic such that the material (and / or the composition comprising the material) has an affinity for a fluoroalkyl analyte. Any of a variety of suitable fluorine-containing moieties are possible, as described herein in greater detail.

[0156] The material may comprise fluorine in any of a variety of suitable amounts. In some embodiments, for example, the material comprises fluorine in an amount greater than or equal to 10 wt.%, greater than or equal to 20 wt.%, greater than or equal to 30 wt.%, greater than or equal to 40 wt.%, greater than or equal to 50 wt.%, greater than or equal to 60 wt.%, greater than or equal to 70 wt.%, or greater than or equal to 80 wt.% versus a total weight of the material. In certain embodiments, the material comprises fluorine in an amount less than or equal to 90 wt.%, less than or equal to 80 wt.%, less than or equal to 70 wt.%, less than or equal to 60 wt.%, less than or equal to 50 wt.%, less than or equal to 40 wt.%, less than or equal to 30 wt.%, or less than or equal to 20 wt.% versus a total weight of the material. Combinations of the above recited ranges are also possible (e.g., the material comprises fluorine in an amount greater than or equal to 10 wt.% and less than or equal to 90 wt.% versus a total weight of the material, the material comprises fluorine in an amount greater than or equal to 50 wt.% and less than or equal to 60 wt.% versus a total weight of the material). Other ranges are also possible.

[0157] According to certain embodiments, the material has a first solubility. In certain embodiments, for example, the material may be at least partially soluble (e.g., fully soluble) in at least one liquid (e.g., water). In some embodiments, the material may be at least partially dispersed (e.g., fully dispersed) in at least one liquid (e.g., water).

[0158] According to some embodiments, the solubility of the material in water refers to the hydrophilic character of the material, i.e., the ability of the material to have an affinity for water. The hydrophilic character of the material may be induced by hydrogen bonding and / or ionic interactions of the material with water.

[0159] The material may comprise any of a variety of suitable materials. In some embodiments, for example, the material comprises a polymer. In certain embodiments, the material (e.g., polymer) comprises repeating ethylene glycol units. In some embodiments, each ethylene glycol unit comprises one or more fluorine-containing moieties (e.g., fluoroalkyl-containing moieties).

[0160] According to some embodiments, the material (e.g., polymer) comprises a basic moiety. The basic moiety may be positively charged, in accordance with certain embodiments. For example, in some embodiments, the basic moiety comprises a positively charged amine.

[0161] In some embodiments, the material is configured to interact with a fluoroalkyl analyte. In some embodiments, for example, the material forms a conjugate material comprising the fluoroalkyl analyte. The conjugate material may, in certain embodiments, be a poly mer-fluoro alkyl analyte conjugate. According to some embodiments, the conjugate material comprising the fluoroalkyl analyte (e.g., the polymer-fluoroalkyl analyte conjugate) may have the first solubility. For example, in some embodiments, the conjugate material comprising the fluoroalkyl analyte is at least partially soluble and / or dispersed in at least one liquid (e.g., water).

[0162] In certain embodiments, the conjugate material comprising the fluoroalkyl analyte (e.g., the polymer-fluoroalkyl analyte conjugate), in response to a stimulus, has a second solubility that is less than the first solubility. According to some embodiments, for example, the conjugate material comprising the fluoroalkyl analyte (e.g., polymer- fluoroalkyl analyte conjugate), in response to a stimulus, may be at least partially insoluble (e.g., fully insoluble) in at least one liquid (e.g., water). In some embodiments, the material may be at least partially precipitated (e.g., fully precipitated) in at least one liquid (e.g., water). In certain embodiments, the conjugate material comprising the fluoroalkyl analyte (e.g., the polymer-fluoroalkyl analyte conjugate) forms a precipitate and / or an aggregate in response to a stimulus.

[0163] The stimulus may be any of a variety of suitable stimuli. In certain embodiments, for example, the stimulus is an increase in temperature (e.g., of the at least one liquid). In some embodiments, the stimulus is an increase from less than or equal to room temperature (e.g., 23 °C) to a temperature greater than or equal to 70 °C. In certain embodiments wherein the material (e.g., polymer) comprises repeating ethylene glycol units, the stimulus may be the increase in temperature (e.g., of the at least one liquid).

[0164] According to some embodiments, the stimulus is an increase in solution pH. According to certain embodiments wherein the material (e.g., polymer) comprises a basic moiety (e.g., a positively charged basic moiety, such as a positively charged amine), the stimulus may be the increase in solution pH. For example, in some embodiments, the conjugate material comprising the fluoroalkyl analyte (e.g., the polymer-fluoroalkyl analyte conjugate) may be at least partially insoluble at solution pH levels where the basic moiety is not protonated (e.g., basic solution pH levels, such as a solution pH greater than 7).

[0165] Other stimuli are also possible, including, for example, changing a concentration of other ions in the at least one liquid and / or the adding non-aqueous solvents to the at least one liquid.

[0166] According to some embodiments, the conjugate material (e.g., the polymer- fluoroalkyl analyte conjugate) is configured to release the fluoroalkyl analyte in response to a second stimulus.

[0167] The second stimulus may be any of a variety of suitable stimuli. In some embodiments, for example, the second stimulus is a decrease in temperature (e.g., of the at least one liquid). In certain embodiments, the second stimulus is a decrease from a temperature greater than or equal to 70 °C to less than or equal to room temperature. In certain embodiments wherein the material (e.g., polymer) comprises repeating ethylene glycol units, the second stimulus may be the decrease in temperature (e.g., of the at least one liquid).

[0168] In certain embodiments, the second stimulus is a decrease in solution pH. According to certain embodiments wherein the material (e.g., polymer) comprises a basic moiety (e.g., a positively charged basic moiety, such as a positively charged amine), the second stimulus may be the decrease in solution pH. For example, in some embodiments, the conjugate material comprising the fluoroalkyl analyte (e.g., the polymer-fluoroalkyl analyte conjugate) may be at least partially soluble at solution pH levels where the basic moiety is protonated (e.g., acidic solution pH levels, such as a solution pH less than or equal to 7).

[0169] Other second stimuli are also possible, including, for example, changing a concentration of other ions in the at least one liquid and / or the adding non-aqueous solvents to the at least one liquid.

[0170] In certain embodiments, the precipitate and / or the aggregate of the conjugate material comprising the fluoroalkyl analyte (e.g., polymer-fluoroalkyl analyte conjugate) is collected on a sensor (e.g., sensor 302a, 302b, and / or 302c) after applying the stimulus. The precipitate and / or the aggregate of the conjugate material comprising the fluoroalkyl analyte may be collected on the sensor such that the precipitate and / or the aggregate of the conjugate material contacts at least a portion of the conducting material (e.g., the conducting polymer). In some embodiments, the fluoroalkyl analyte is released from the precipitate and / or the aggregate of the conjugate material comprising the fluoroalkyl analyte (e.g., polymer-fluoroalkyl analyte conjugate) collected on the sensor by applying the second stimulus. In certain embodiments, the released fluoroalkyl analyte is detected using the sensor.

[0171] According to some embodiments, after releasing the fluoroalkyl analyte in response to the second stimulus, the material may have the first solubility. For example, in certain embodiments, the material comprising the fluoroalkyl analyte is at least partially soluble and / or dispersed in at least one liquid (e.g., water).

[0172] The composition comprising the material comprising at least one fluorine- containing moiety may be used in any of a variety of suitable applications, including, for example, the capture (e.g., preconcentration) and / or release of a fluoroalkyl analyte in conjunction with the sensors described herein, liquid chromatography, and / or mass spectrometry. Other applications are also possible.

[0173] According to certain embodiments, preconcentrating methods are described. In some embodiments, a preconcentrating method comprises exposing a material (e.g., a polymer) comprising at least one fluorine-containing moiety to a sample suspected of comprising a fluoroalkyl analyte. The sample may, in certain embodiments, comprise at least one liquid (e.g., water). As described herein in greater detail, the material comprising at least one fluorine-containing moiety may have a first solubility. In some embodiments, for example, the material comprising at least one fluorine-containing moiety is at least partially soluble and / or dispersed in at least one liquid (e.g., water).

[0174] In some embodiments, exposing the material comprising at least one fluorine- containing moiety to a fluoroalkyl analyte forms a conjugate material comprising the fluoroalkyl analyte (e.g., a polymer-fluoroalkyl analyte conjugate). As described herein in greater detail, the conjugate material comprising the fluoroalkyl analyte (e.g., the polymer-fluoroalkyl analyte conjugate) may have the first solubility. For example, in some embodiments, the conjugate material comprising the fluoroalkyl analyte is at least partially soluble and / or dispersed in at least one liquid (e.g., water).

[0175] In some embodiments, the method comprises applying a stimulus to precipitate and / or aggregate at least a portion of the conjugate material comprising the fluoroalkyl analyte, if present, in the sample. As described herein in greater detail, in response to the stimulus, the conjugate material comprising the fluoroalkyl analyte (e.g., the polymerfluoroalkyl analyte conjugate) may have a second solubility that is less than the first solubility. In some embodiments, for example, the conjugate material comprising the fluoroalkyl analyte (e.g., the polymer- fluoroalkyl analyte conjugate) is at least partially insoluble and / or precipitated in at least one liquid (e.g., water). In certain embodiments, in response to the stimulus, the conjugate material comprising the fluoroalkyl analyte (e.g., the polymer-fluoroalkyl analyte conjugate) forms a precipitate and / or an aggregate.

[0176] As described herein in greater detail, the stimulus may be any of a variety of stimuli, including, for example, an increase in temperature (e.g., of the at least one liquid) and / or an increase in solution pH.

[0177] In some embodiments, the method comprises exposing the conjugate material comprising the fluoroalkyl analyte, if present, to a sensor (e.g., sensor 302a, 302b, and / or 302c) configured to detect the fluoroalkyl analyte. For example, in certain embodiments, the method comprises exposing the precipitate and / or the aggregate of the conjugate material comprising the fluoroalkyl analyte, if present, to the sensor.

[0178] According to some embodiments, the method comprises applying a second stimulus to release the fluoroalkyl analyte, if present, from the conjugate material comprising the fluoroalkyl analyte, if present. As described herein in greater detail, in response to the second stimulus, the conjugate material comprising the fluoroalkyl analyte (e.g., the polymer-fluoroalkyl analyte conjugate) may have the first solubility. In some embodiments, for example, the conjugate material comprising the fluoroalkyl analyte (e.g., the polymer-fluoroalkyl analyte conjugate) is at least partially soluble and / or dispersed in at least one liquid (e.g., water).

[0179] As described herein in greater detail, the second stimulus may be any of a variety of stimuli, including, for example, a decrease in temperature (e.g., of the at least one liquid) and / or a decrease in solution pH.

[0180] In certain embodiments, the method comprises detecting the fluoroalkyl analyte, if present, using the sensor.

[0181] According to certain embodiments, the fluid and / or the sample described herein comprises at least one liquid (e.g., at least two liquids, at least three liquids, at least four liquids, etc.). According to some embodiments, the at least one liquid is or comprises the fluoroalkyl analyte. In some embodiments, the fluid and / or the sample comprises a solution comprising at least one liquid and the fluoroalkyl analyte at least partially dissolved in the at least one liquid. In some embodiments, for example, the sample and / or the fluid (e.g., solution) comprises water. The water may, in certain embodiments, be sourced from any of a variety of suitable sources, including, for example, from a home, a well, a body of water (e.g., an ocean, a sea, a pond, a lake, a river, and the like), a residential unit, a commercial unit, an industrial plant, a semiconducting manufacturing site, a water treatment site, a water distribution site, a food manufacturing site, an irrigation site, an industrial waste stream, a landfill leachate, a contaminated site, a (pre)concentrator system, and / or a landfill. Other water sources are also possible. In some embodiments, for example, the water is sourced from food.

[0182] In some embodiments, the fluid (e.g., solution) and / or the sample comprises at least one organic solvent. In certain embodiments, the fluid (e.g., solution) and / or the sample comprises water and at least one organic solvent.

[0183] According to some embodiments, the fluid and / or the sample comprises at least one gas (e.g., at least two gases, at least three gases, at least four gases, etc.). In certain embodiments, the at least one gas is or comprises the fluoroalkyl analyte.

[0184] In certain embodiments, the gas comprises less than or equal to 8 carbon atoms (e.g. less than or equal to 6 carbon atoms, less than or equal to 5 carbon atoms, less than or equal to 4 carbon atoms, etc.). In some embodiments, the gas comprises at least one fluorine-containing moiety.

[0185] In certain embodiments, the fluid and / or the sample comprises a mixture of gases comprising oxygen, nitrogen, carbon monoxide, carbon dioxide, and / or combinations thereof.

[0186] According to some embodiments, the fluid and / or the sample comprises an aerosol (e.g., a suspension of solid particles or liquid droplets in a gas).

[0187] In some embodiments, the fluid and / or the sample comprises a refrigerant.

[0188] In certain embodiments, an analyte described herein is a fluoroalkyl substance (e.g., a fluoroalkyl analyte). As used herein, the term “fluoroalkyl substance” refers to a molecule comprising an alkyl group in which one or more hydrogens have been substituted with fluorine. The fluoroalkyl substance may be any of a variety of suitable fluoroalkyl substances. In certain embodiments, the fluoroalkyl substance is a perfluoroalkyl substance and / or a polyfluoroalkyl substance (PFAS).

[0189] According to some embodiments, the fluoroalkyl substance is a Brpnstcd acid. In certain embodiments, the fluoroalkyl substance (e.g., Brpnstcd acid) comprises a sulfate (R-O-SCU) moiety, a sulfonate (R-SCL') moiety, and / or a carboxylate (R-CO2') moiety. According to certain embodiments, the fluoroalkyl substance comprising a sulfate moiety, a sulfonate moiety, and / or a carboxylate moiety may be configured to dissociate in water to provide a conjugate base of the fluoroalkyl substance and a hydronium ion (H3O+). In some embodiments, the hydronium ion may be configured to protonate (e.g., acid dope) a conducting polymer (e.g., a Brpnsted base), thereby increasing the conductivity of the base polymer, as described herein in greater detail.

[0190] In some embodiments, the fluoroalkyl substance comprises 2-(N-methyl- perfluorooctane sulfonamido) acetic acid, perfluorobutane sulfonic acid, perfluorohexane sulfonic acid, perfluoroheptanoic acid, perfluorooctane sulfonic acid, perfluoromethylheptane sulfonic acid, perfluorobutanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, conjugates thereof, and / or combinations thereof. Other fluoroalkyl substances are also possible.

[0191] International Patent Application No. PCT / US2023 / 062268, filed February 9, 2023, and entitled “Lateral Flow Assay for Quantitative and Ultrasensitive Detection of Analyte,” and U.S. Provisional Patent Application No. 63 / 656,093, filed June 4, 2024, and entitled “Conducting Compositions for Detection of Fluoroalkyl Substances and Related Articles, Systems, and Methods,” are incorporated herein by reference in their entirety for all purposes.

[0192] The following example is intended to illustrate certain embodiments of the present invention, but does not exemplify the full scope of the invention.

[0193] EXAMPLE 1

[0194] The following example describes electrical schemes for the detection of perfluoroalkane substances.

[0195] The electrical resistivity of semiconducting materials is dependent upon the carrier concentrations. As described herein, it is demonstrated that perfluoroalkane substances that have a sulfate or carboxylate can trigger large changes in the conductivity of a fluorophilic sensing composition. The sensing composition is deployed as a thin film coating that can be deposited on a membrane, filter, tubing, or other surface. The electrical responses of the materials to the perfluoroalkane substance can be measured directly by connecting electrodes to the sensing material to perform a simple resistivity measurement. Alternatively, a sensing material can be included in a resonant radio frequency circuit to create a change in the resonance frequencies and / or intensity of the device. Integrated sensors having both a collection and a sensing mechanism are also disclosed.

[0196] Electrical conductivity is a property that has high utility. Sensors that directly output an electrical signal are attractive and can be readily integrated into complex circuits or be measured individually. Electrical resistivity is readily measured and has minimal power requirements. Organic conducting polymers can display a wide range of conductivities that can range from low values of 10'7S / cm to 103S / cm as a function of their oxidation state. Many conducting polymers are wide band gap semiconductors in their undoped state. The wide band gap implies that the excitation of an electron from the filled valence band to the conduction band is not possible at room temperature. Hence when undoped conducting polymers often have high resistivity and in some cases can be considered as insulators. The action of oxidizing or reducing the conducting polymer can dramatically enhance its conductivity. In some conducting polymers the direct protonation of the polymer can also dramatically enhance its conductivity. Some perfluoroalkane substances have carboxylate or sulfonate species which are strong acids and in water are dissociated into their conjugate bases, RCO2' and RSO f respectively. The counter ions to these species in some cases can be the hydronium ion (H3<3+).

[0197] As described herein, fluorous sensing compositions can selectively absorb perfluoro-carboxylic acid and perfluoro- sulfonic acid groups that increase the internal acidity of the sensing material. In some cases, the absorbed species can be the conjugate base of these materials and the hydronium ion. The hydronium ion causes doping of the conducting polymer backbone, increasing the conductivity. In other cases, it is assumed that the PFAS molecule is absorbed into the sensing material without a hydronium ion. The lowering of the internal pH in a sensing composition can be used to change the conductivity of the material. In some cases, the change in conductivity is the result of a protonation of a polymer backbone. In other cases, the change in conductivity is triggered by an acid triggered redox event. The fluorous nature of the composition provides selectivity for the perfluoro alkane Brpnstcd acid materials.

[0198] When protonation of conducting polymers causes increases in conductivity, it is referred to as acid doping. This process is illustrated for poly aniline and polypyrrole in FIG. 5. In these representative examples the level of oxidation may be variable and the action of acid may result in fewer charges than shown. However, the process of protonation of the polymer backbone is known to cause large conductivity changes. Absorption of a PFAS Brpnsted acid into the polymer films can result in protonation of the polymers and increase their conductivity. In some cases, the increase in conductivity is larger than a factor of 10. In some cases, the increase in conductivity is larger than a factor of 100. In some cases, the increase in conductivity is larger than a factor of 1,000. In some cases, the increase in conductivity is larger than a factor of 10,000. In some cases, the increase in conductivity is larger than a factor of 100,000.

[0199] To create specific interactions with fluorous acids, the sensing compositions are configured to have a high affinity for highly fluorinated materials. This feature generally involves having a high degree of fluorine in the materials. The sensing compositions will need to have fluoroalkane groups and in some cases the fluorine composition of the sensing material by weight will be higher than 20%. In some cases, the fluorine composition of the sensing material will be higher than 30%. In some cases, the fluorine composition of the sensing material will be higher than 40%. The fluorine in the sensing composition can be added as a non-covalent additive. For example, in some cases, a conducting polymer can be dispersed with a fluorous additive and deposited to make a sensing material. A non-limiting example of an additive that provides the fluorous selectivity is Krytox-PEG-600-Diamide (KPD), shown in FIG. 6.

[0200] Other fluorous additives are possible. The additive shown in FIG. 6 has two components, a polar central element that can interact and potentially hydrogen bond with the material being dispersed as well as stabilize the dispersions in water. The two other fluorous blocks provide for the affinity to fluorous acids.

[0201] In other cases, the fluorous groups can be added directly to the polymer backbone through covalent linkages. In some cases, the fluorous groups are attached through an ether linkage. In some cases, the fluorous groups are attached through a thio-ether linkage. In some cases, the fluorous groups are attached by a carbon linkage. Nonlimiting examples of polymers with covalent fluorous groups are shown in FIG. 7. The frequency of the fluorous groups along the polymer backbones can be variable and can be controlled by the synthetic methods.

[0202] In some cases, the Brpnstcd activated conducting polymers need not directly have fluorous character, but be in close contact to a fluorophilic material. This can be in a layered or phase separated structure.

[0203] Many conducting polymers are known that undergo redox triggered increases in conductivity. Non-limiting examples of prospective conducting polymers are shown in FIG. 8. In some embodiments, the polymer has affinity to PFAS Brpnstcd acids to selectively absorb the materials. The different R groups shown may be substituted with organo-fluorine groups that provide the selectivity. In certain embodiments, the polymers are in a composite structure with a fluorous material. The deposition of the materials can be in a single dispersion of the fluorophilic material and the conducting polymer, or alternatively a film of a conducting polymer can be coated with a fluorophilic material. These composite materials may also include a group that will oxidize the polymer to raise its conductivity in response to the binding of a PFAS Brpnstcd acid. The polymers shown in FIG. 8 can be used together as mixtures or with other conducting elements such as carbon, graphite, graphene, carbon nanotubes, or other electrically conductive inorganic materials.

[0204] In some embodiments, a polymer is functionalized with fluorophilic groups after it is polymerized. As shown in FIG. 9, polypyrrole can be synthesized by oxidative polymerization to produce an electrically conductive doped composition, wherein some of the pyrrole rings have positive changes associated. In this state the protons on nitrogen atoms bearing the charge are more acidic and can be deprotonated. The act of deprotonation causes the polymer to have low conductivity. This polymer can undergo facile thiol-Michael addition reactions with a thiolate. After this reaction, a series of proton transfer and tautomerization reactions reestablish the polypyrrole structure, however the charges in the pyrrole rings are reduced by the action of the thiol-Michael addition reaction. The R group in the thiolate can comprise a fluorophilic group and hence the polymer composition can be transformed into a sensing material. Hence after the thio-Michael addition reaction and equilibration the polypyrrole has reduced doping and low conductivity. The addition of groups that undergo PFAS triggered enhanced oxidation can produce a sensor. In effect the PFAS triggers a doping reaction that can result in a conductivity increase. It is also possible to oxidize the functional polypyrrole so that there are charges in the pyrrole rings and to again deprotonate the material to give a low conductivity state. This material could in some embodiments be reacted in a second thio-Michael reaction to add additional functionality, or can be used to detect PFAS directly. In the latter embodiment the absorption of PFAS causes protonation of the pyrrole rings to create the doped state and increase the conductivity.

[0205] Carbon nanotubes can be covalently or noncovalently functionalized to interact with PFAS Brpnsted acids. In some cases, the carbon nanotubes are single walled and semiconductive. In these materials the injection of carriers can cause large increases in resistivity. Hence composites of semiconductive carbon nanotubes that are fluorophilic and have PFAS activated oxidants can also be used as sensory materials. Inorganic conducting materials can also be used as conductors if their level of doping is modulated with the action of PFAS Brpnstcd acids.

[0206] Oxidation reactions can be triggered by acid groups. There are many examples wherein organic molecules of inorganic species can be made to be more oxidizing with the action of acid. In one example, quinones take up two protons with oxidation and hence their redox potential is pH dependent. At low pH quinones are stronger oxidants. If a sensor composition contains a material that can be made to be more oxidizing with action of acid, then this method can be used to oxidatively dope a conducting material. Non-limiting examples of the material being oxidized include polypyrroles, polythiophenes, polyanilines, polyarylene vinylenes, carbon nanotubes, and / or metal chalcogenides. In some embodiments, the sensing compositions have fluorophilic character and ideally the pH activated oxidants also have fluorophilic character to provide for a homogenous stable sensing composition. Non-limiting examples of pH activated organic oxidants are shown below in FIG. 10. These materials can be modified to include fluorous elements to increase the compatibility with the fluorophilic conducting elements. These oxidants can be used to change the conductivity of conducting polymers, carbon nanotubes, graphene, or semiconductive p-type conductors. The oxidation potential of the oxidant will be matched with the conducting material to produce an optimal response, wherein the oxidant and conductor can produce a stable composition that only is activated with action of a fluorous acid.

[0207] The mechanisms of the different oxidants will be variable. In some cases, the oxidation is accompanied by an irreversible chemical reaction. In other cases, the protonation of the species and the associated oxidation reaction can be reversible. In some embodiments, an irreversible reaction is preferred and in others the reversibility may be preferred.

[0208] There are many inorganic materials that can be activated to be stronger oxidants by action of Brpnstcd acids. These include metal coordination compounds, metal oxides, and / or metal halides. In some cases, the protonation produces positive charge on a material and increases its electron affinity.

[0209] The measurement methods using the PFAS selective chemiresistive schemes discussed herein involve exposing the sensing material to a solution of interest and measuring the increase in the conductivity of the sensing material. The sensing material can be applied to many different surfaces including paper, polymers, membranes, skin, textiles, ceramics, plants, and wood. The sensing material can be deposited in a single step. The sensing composition will comprise a conducting polymer or semiconducting carbon nanotube, groups that produce an affinity for PFAS chemicals, and optionally a molecule that oxidatively dopes the conducting polymer or semiconducting carbon nanotube in the presence of PFAS. In some cases, the conducting polymer or semiconducting carbon nanotube can have intrinsic sensitivity to the PFAS. Such is the case when the conducting polymers can be doped by protonation of the polymer backbone. In other cases, a PFAS triggered oxidation is employed.

[0210] In some embodiments the sensing composition can be assembled in multiple deposition steps. A conducting polymer or semiconducting carbon nanotube can be first deposited. This polymer may optionally have fluorophilic character. In the event additional fluorophilic character is needed, a second fluorophilic material can be deposited on top of the first material. This second material can be polymeric, molecular, or functionalized nanoparticles. In some cases, the fluorophilic material will contain perfluoro-alkane segments. The material may also contain elements that cause it to interact with the conducting polymer or semiconducting carbon nanotube. A nonlimiting example of a material that can be coated onto a conducting polymer or semiconducting carbon nanotube is the triblock polymer shown in FIG. 6. This polymer may also be part of a premixed formulation and be used in the single step deposition of the sensing material.

[0211] In cases wherein a PFAS-sensitive oxidizing group is employed, the oxidizing group can be added in the dispersion used in the single step deposition or added separately. It can be added in a step that only adds the oxidant or can be added with another fluorophilic material. The oxidant in some embodiments will have a fluorophilic element to ensure that that the composition is stable.

[0212] The sensing compositions can be deposited by dip coating, polymerization on the substrate, spray coating, blade coating, silk screening, vapor deposition, ink jet printing, extrusion, fiber spinning, electrospinning, abrasion, or combinations thereof. The choice of the deposition method will be based on the properties of the material, including its particle size and viscosity, and / or the substrate upon which the material is going to be deposited. The sensing compositions will often be deposited from a solution or dispersion in a solvent. The solvent can have fluorous characteristics and in some cases the solvent will be hexafluoro-isopropanol. The solvent can also be aromatic, an ether, or a halogenated hydrocarbon. In some cases, the solvent may be water and the sensing material is dispersed in an aqueous colloidal dispersion.

[0213] In some cases, the sensing material is deposited on a membrane. The membrane can transport a solution to be analyzed by wicking the solution into the membrane. In one embodiment of this method the sensing material is included in a lateral flow assay. In other cases, the membrane can be used as a filter and a solution can be passed through the filter. This method has the advantage that large volumes of water can be passed through the filter and allow for larger quantities of PFAS to be absorbed into the sensing material and thereby produce lower detect limits. In some cases, the filtration method can be referred to as a vertical flow assay.

[0214] In some cases, multiple sensing material compositions are employed in a given sensing device for multimodal analyte detection. Some compositions may be more sensitive to one type of PFAS than another and in some other cases may be configured to evaluate other non-PFAS characteristics of the sample. For example, one or more sensing materials may be configured to measure pH or the solution resistance to determine ionic conductivity. The monitoring of the conductivity of the sensing material can be done continuously or at the end of the wicking or filtration of a sample. In some cases, it will be an advantage to allow the sensing material and its associated support to be partially dry to lower the base conductivity of the material that can be the result of it being swollen in water. Dry, or partially dry, samples can in some cases allow for a more precise determination of the concentration of the PFAS in the sample. In some cases, the samples are allowed to dry for 1 minute before measuring its electrical conductivity, in other cases the sample’s electrical conductivity is measured after 10 minutes, in other examples the sample’s electrical conductivity is measured after 30 minutes, in other cases a sample is allowed to dry for 1 hour before measuring the electrical conductivity. Drying can also be accelerated by gentile heating of the sample. In some cases, the sample is heated to 40 °C and in some cases the sample is heated to 50 °C. In some cases, the electrical properties of the sensing material are determined by integration into a resonant radio frequency circuit. The use of a radio frequency identification (RFID) device is that spatial and temporal data can be detected. This data can be used to correlate PFAS levels at multiple locations and in some cases can be used to determine / indicate the presence of the PFAS.

[0215] PFAS measurements can be facilitated by preconcentration, and fluorophilic polymers that have triggered aggregation can be used to capture PFAS from water solutions. In some cases, polymer aggregation is triggered by heating the water solution. This effect is caused by a balance of the hydrogen bonding of one part of the polymer with water with the tendency of the fluorophilic part of the polymer wanting to assemble because of complementary fluorophilic interactions. PFAS can preassemble with the polymer in its soluble state and then when it aggregates the PFAS is drawn into particles. Separation of the particles and dissolution into a much smaller volume solvent then concentrates the PFAS. Fluorophilic polymers that aggregate with heating are shown in FIG. 11. Also, a picture of a polymer with equal amounts of the fluorous and ethylene glycol repeating units is shown in FIG. 12 and above the aggregation temperature (T = 80-90 °C). The cloudy nature of the solution confirms aggregation. The higher the ethylene glycol component the higher the temperature at which the polymer aggregates. This is expected because the ethylene glycol is providing for the solubility with the water solvent. With heating the hydrogen bonding interactions that are critical to the water solubility are weakened and the polymer aggregates.

[0216] Changes in pH can also trigger the aggregation / precipitation of a preconcentrating polymer. In some cases, a polymer that has a basic group, such as an amine, can be soluble at pH levels wherein the amine is protonated and insoluble at pH levels wherein the amine is not protonated. A non-limiting example is the polymer shown in FIG. 13 which can be compositionally adjusted to be soluble and aggregate at desired pH levels. In this case the aggregated polymer and associated PFAS can be collected on a filter and with acid treatment the PFAS can be liberated. This method can be readily used wherein a solution is first treated with the polymer, which in some cases can be soluble at neutral pH. Raising the pH causes an aggregation and the solution is filtered leaving polymer particles on the filter paper. Then a much smaller volume of water is added at a pH level that dissolves the polymer and liberates the PFAS to absorb into the sensing material that is on the same filter. In this way the same filter collects the particles and serves to give the sensor response.

[0217] The above preconcentrator polymer and methods have general utility and can be used with other sensor methods, including electrochemical sensors and established liquid chromatography mass spectrometric methods. The preconcentrator materials may release PFAS to a sensor by a number of different stimuli including temperature changes, changes in pH, changes in the concentration of other ions, or the addition of non-aqueous solvents.

[0218] Described herein is a conducting polymer sensing composition containing a perfluoro alkane component such that when PFAS is absorbed into the composition the conductivity of the material is higher. In some embodiments, the conductivity difference can be raised by a factor of 1000 or more by action of PFAS. In certain embodiments, the PFAS induced conductivity change is the result of protonation of the conducting polymer. In some embodiments, the PFAS induced conductivity change is the result of charge injection into the conducting polymer.

[0219] In certain embodiments, the perfluoro alkane component is introduced by mixing of two different materials. In other embodiments, the perfluoro alkane component is covalently attached to the conjugated polymer. In some embodiments, an acid responsive element is added that produces a conductivity enhancement in the conducting polymer with PFAS action. In certain embodiments, a fluoroalkane containing acid responsive element is added that produces a conductivity enhancement in the conducting polymer with PFAS action.

[0220] According to some embodiments, a method for detecting PFAS at lower than 1 ppb is described, wherein the method uses a conducting polymer that increases its conductivity in response to PFAS.

[0221] In some embodiments, a sensor is described. In certain embodiments, the sensor is a lateral flow assay device. In some embodiments of the sensor, the conducting polymer is in a membrane. In certain embodiments of the sensor, the conducting polymer is in a filter. In some embodiments of the sensor, the conducting polymer is integrated into a vertical flow assay.

[0222] In certain embodiments, the sensor allows for the determination of multiple analytes.

[0223] In some embodiments, the sensor can be powered and read wirelessly. In certain embodiments, the sensor uses a passive RFID device. In some embodiments, the sensor can be read wirelessly by a smartphone.

[0224] In certain embodiments, polymer precipitate designed to concentrate PFAS is collected on a chemiresistive sensor membrane or filter and then triggered to release the PFAS. In some embodiments, a volume of water is passed through a membrane to allow for the detection of PFAS.

[0225] EXAMPLE 2

[0226] The following examples describes resistivity detection of perfluoroalkyl substances (PFAS) with fluorous-polyaniline in an electrical lateral flow sensor.

[0227] Described herein is a simple and inexpensive perfluoroalkyl acid detection method based on an electrically read lateral flow assay (e-LFA). The method employs a fluorous surfactant formulation with undoped polyaniline (F-PANI) fabricated to create test lines for the lateral flow assay. In perfluoroalkyl acid sensing studies, an increase in conductivity of the F-PANI film is caused by acidification and doping of PANI. A conductivity enhancement by 104-fold can be produced by this method, and a limit of detection for perfluorooctanoic acid (PFOA) of 400 ppt and perfluorobutanoic acid (PFBA) of 200 ppt is demonstrated. The method for PFOA detection can be expanded for wide-scale environmental and at-home water testing.

[0228] Lateral Flow Assays (LFAS) have garnered a broad public acceptance for sensing in healthcare and offer expanded applications for environmental sensing with facile implementation. With the increasing concern for the widespread detection of per- and poly-fluoroalkyl substances (PFAS), selective sensing is imperative for monitoring these harmful chemicals in the environment and drinking water. A low-cost and sensitive detection method for quantifying PFAS with an e-LFA is described. PFAS dopes the polyaniline (PANI) to increase conductivity and enable e-LFA detection. The method harnesses the fluorous effect to selectively target perfluoroalkyl acids, over their non- fluorous equivalents. The F-PANI fabricated e-LFA exhibits a 400 ppt detection limit for PFOA and provides quantitative measurements from simple resistivity measurements.

[0229] PFAS: Per- and poly-fluoroalkyl substances (PFAS) contain fully fluorinated alkyl groups, and have been widely used to provide waterproof, anti-stain, and heatresistance properties. However, their extraordinary stability has allowed for accumulation in water supplies and this is now recognized as a serious threat to public health. Studies show that PFAS may result in adverse effects including increased cholesterol levels, thyroid disease, liver damage, kidney cancer, testicular cancer, developmental effects affecting the unborn child, and other environmental damage. In response to this issue, the US Environmental Protection Agency (EPA) has introduced regulatory guidance to limit the amount of six different PFAS in drinking water with levels of 4 ppt (4 ng- L1) for perfluorooctanoic acid (PFOA) and 1 ppt for perfluorobutanoic acid (PFBA) in March 2023. Currently, the EPA employs liquid chromatography, and mass spectrometry for PFAS detection at the ng L'1level. Yet, these methods are time-consuming, expensive, require well-trained personnel, and must be performed in laboratory environments. To facilitate broader testing and source attribution, fast, portable, user-friendly, and low-cost PFAS sensing methods are needed that robustly meet the EPA required ppt detection limits.

[0230] Reported herein is a PFAS sensing platform based on the conducting polymer, polyaniline (PANI), and electrical lateral flow assay (e-LFA). PANI is an attractive material to create sensors, as a result of its facile synthesis, high stability, and large conductivity changes caused by protonic doping as described in FIG. 14. To target PFAS responsive polymer coatings, a fluorous surfactant (Krytox-PEG-600-diamide, KPD) was mixed with emeraldine free (PANI-EB) state by ultrasonication in water to create a dispersion as shown in FIG. 15. Therefore, a material was provided that selectively absorbs PFAS as a result of fluorous interactions. In the case that the functional groups of PFAS contain acidic functionality, absorption will result in acidification of the film and a transition of the PANI from its insulating emeraldine free (PANI-EB) state to highly conductive emeraldine salt (PANI-ES) polymer (FIG. 16). To create responsive sensory devices, a KPD-(PANI-EB) test line was printed on nitrocellulose (NC) membranes. Aqueous perfluoroalkyl acid solutions move by capillary force along the NC membrane and a calibrated amount of water transverses the conducting polymer test line to produce an economical, fast, quantitative, and easy-to- use flow assay.

[0231] Preparation of Polyaniline Nanofibers, Ink, and Test Lines: PANI is polymerized in nanofiber form to ensure high surface area to enhance analyte interactions. Nanofibers with diameters around 80 nm were produced by an interfacial oxidative polymerization method using camphorsulfonic acid and ammonium persulfate (FIG. 20). The synthesized PANI-ES (emeraldine salt) powder is then converted to undoped PANI-EB (emeraldine base) by treatment (washing then filtration) with ammonium hydroxide solution. PANI-EB formation is confirmed by Fourier-transform infrared spectroscopy (FTIR) with a quinoid ring stretching at 1576 cm'1, benzenoid ring stretching at 1491 cm' C-N stretching modes at 1378 cm'1and 1295 cm'1(FIG. 20).

[0232] The Fluorous-PANI-EB (F-PANI) ink is prepared by mixing PANI-EB dispersion with Krytox-PEG-600-diamide (KPD) solution and sonicating for 30 minutes (FIG. 15). The ink is likely stabilized by the noncovalent interactions between KPD (amide and ether groups) and the nitrogen atoms of PANI-EB as shown schematically in FIG. 15. Deposition of F-PANI ink on nitrocellulose (NC) membrane or filter paper substrates resulted in test line bands. Detailed procedures for the preparation of the materials and test lines are described herein.

[0233] Scanning electron microscopy (SEM) images reveal microcracks in the surface of coatings formed on the NC membrane (FIGS. 17A-17B). The dehydration of PANI likely provides the stresses that result in the microcracks that are not apparent with visual inspection. Microcracks still remained in the wet F-PANI coating. The rehydration and swelling of the materials likely occur during the sensing experiments, and although the microcracks can produce unwanted resistance in the test lines, they may also provide for expanded interactions with the aqueous solutions for improved partitioning of the analytes into the films. The crack widths of the F-PANI coating are ca. 3 pm, which is smaller than those observed in the coating (ca. 15 pm) produced from pure PANI-EB inks. The fluorous surfactant prevents aggregation between PANIs and hence favors smaller features. The F-PANI is expected to be less hydrophilic than PANI-EB and this was evaluated by measuring contact angles (9) of water droplets placed on the films (FIG. 18). It was confirmed that the F-PANI coating presents a hydrophobic surface regardless of the substrate, whereas the PANI-EB coating surface is hydrophilic.

[0234] Factors that Affect the Conductivity of Test Lines: Resistance measurements were collected with a four-point probe. Multiple measurements on each test line were performed to investigate the uniformity of the materials. As shown in FIG. 19, the conductivity is influenced by multiple different factors. The resistance of the F-PANI test line decreases after exposure to aqueous solutions of PFOA (FIG. 20). Hydration of the test line is important and if a test strip is removed from the solution and air-dried for 15 minutes the water evaporates and the test lines display a high resistance >220 MQ, which is the limit of detection. This feature is due to the cationic (polaron) and dicationic (bipolaron) carriers that are pinned by attractive electrostatic interactions with the counterions in the absence of water. Water reduces these interactions by a solvation of the ions / carriers by a combination screening and separation of the charges. To avoid dehydration, resistivity measurements were made within 5 minutes after the sample was removed from the vial to ensure full hydration. The absorption of perfluoroalkyl acids into the polymer coating is important in obtaining an optimal response, and this is facilitated by the fact that the solution passes very slowly through the hydrophobic F- PANI test line (FIG. 18). Solutions require 20 minutes to completely pass through the F- PANI test line, whereas only 90 seconds is required with an equivalent PANI-EB test (FIG. 29). FIG. 21 shows that the test line reaches a constant resistance value of approximately 67 MQ after 30 minutes of being dipped into a 10'6M PFOA solution. Hence, the main time limitation is the transport of the water along the NC membrane and the absorption of the PFBA and PFOA with concurrent protonic doping of F-PANI is a relatively rapid process. Therefore, resistivity measurements were made after 30 minutes of the test strip being placed in the solution.

[0235] The width of the F-PANI test line was investigated. Lines with widths of 0.3 cm, 0.7 cm, and 1.4 cm were created using 17 / / L, 40 / / L, and 80 L of F-PANI ink, respectively. They had similar thicknesses (27.9 ± 5.9 f m). It was found that test lines 0.7 cm or less provided consistent results over a range of analyte concentrations (FIGS. 22-23). Wider test lines (1.4 cm) displayed higher resistances with 10'2M PFOA and large standard deviations (86.7 ± 79.7 kfl) as compared to the 0.7 cm lines (30.7 ± 17.5 kfl). It is likely that in these cases protonic doping is not uniform throughout the test line. The data for other concentrations are consistent with the previous results. As a result, test line widths of 0.7 cm were used to determine the sensor performance.

[0236] Ultratrace PFAS detection: The performance of the F-PANI lateral flow devices was evaluated for PFOA detection. The resistance measurements are limited to values less than 220 MQ, which is the resistance of the assay with PFAS-free water. The histogram of resistance values of F-PANI test lines on the NC membrane for each concentration of perfluorooctanoic acid (PFOA) is shown in FIG. 24. Because of nonuniformity in the films, the resistance for each concentration taken with a colinear 4- point probe has a distribution rather than a single clear value. The distribution could potentially be the result of microcracks of the coating that can complicate the conductive pathways and also from non-uniform protonic doping of the PANI backbone. For the statistical analysis of the data, the data was fit to single Gaussian functions to obtain the peak value of resistance (RM) for each concentration and its standard deviation (CM). NO data is omitted. This method allows for avoidance of bias in the data by excluding outliers. The detection limit of an analyte is the concentration at which the value obtained by adding the standard deviation (CM) to the peak resistance value (RM) acquired at a certain concentration begins to fall below 220 MQ which is the resistance of the assay with PFAS-free water as the concentration increases. For PFOA, the detection limit is 400 ppt (10‘9M) and the change in conductivity increases by 104-fold for a 10'2M PFOA concentration. FIG. 19 summarizes the resistance and conductivity values of the F-PANI test lines on NC membranes as a function of PFOA concentration. Similarly detailed data for OA was also obtained. FIG. 25 shows the plots of conductivity of F-PANI test lines on NC membrane as a function of PFOA and its non-fluorous form (octanoic acid, OA) concentrations obtained by Gaussian fitting of the histogram of resistance values. The aqueous PFOA analyte shows higher conductivity compared to OA at the same concentration.

[0237] The effect of different substrates was also tested. FIG. 26 shows the plots of conductivity of F-PANI test lines on NC membrane and filter paper substrates as a function of PFOA concentrations. The conductivity responses are independent of the substrate and correlate with the PFOA concentration. A flow assay using PANI-EB is 105times less sensitive to PFOA with a detection limit of 10'4M. It was also found that the performance of the F-PANI test lines was the same when the aqueous media was changed from D.I. water to local (Cambridge, MA) tap water. The F-PANI lateral flow assay is also capable of detecting PFBA at 10'9M (200 ppt) similar to the PFOA limits of detection. High selectivity for the fluorous acid over the non-fluorous equivalent, butyric acid, (BA), was observed, which gives responses that are 104times lower.

[0238] A simple electrical lateral flow assays (e-LFAs) for the detection of PFOA with limits of detection down to 400 ppt has been developed. Although additional optimization and larger sample sizes than used in current e-LFA are necessary to align with the current US EPA limits, the remarkably low detection thresholds of this sensor scheme render it promising for on-site PFAS detection. The transduction method is the protonic acid doping of polyaniline in its insulating emeraldine base form (PANI-EB) to produce an electrical conducting emeraldine salt (PANI-ES). A formulation of PANI- EB and a fluorous polymeric surfactant creates a conducting polymer with a fluorous character (F-PANI). Test lines of F-PANI are printed on nitrocellulose membranes or filter paper, and wicking of aqueous solutions results in the flow of water through the polymer test line. When PFOA is present, it is absorbed into the F-PANI and acidifies the film resulting in protonic doping of the PANI to create charge carriers. This simple, inexpensive, rapid, and quantitative PFAS detection method is ideally suited for monitoring PFAS in areas, such as military bases, airports, and industrial locations where PFAS exposure is a concern.

[0239] Materials and Characterization: Aniline (ACS reagent, >99.5%), ammonium persulfate (ACS reagent, >98%), and camphorsulfonic acid (>98%) were purchased from Sigma-Aldrich and used as received. The fluorous surfactant, Krytox-PEG-600-diamide (KPD) was synthesized by the previously reported procedure and purchased from Akita Innovations LLC. All solvents used were of HPLC grade. All aqueous solutions were prepared, and samples were rinsed using Milli-Q water. The nitrocellulose membrane strip with a polyester backing card was purchased from GE Healthcare Life Sciences. The filter paper (494, Quantitative) for the substrate was purchased from VWR International.

[0240] SEM images of the film were obtained by a Merlin and Crossbeam 540 Zeiss scanning electron microscope. The TEM images of nanofibers were obtained with a 120 kV FEI Tecnai Multipurpose transmission electron microscope. A Thermo Scientific Nicolet 6700 FT-IR instrument with a Ge crystal was used to obtain attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectra. Resistivity measurements were conducted by a Keithley 2400 and a Signatone four-point probe. The thickness of the coating on the nitrocellulose membrane was obtained with a Dektak 6M stylus profilometer.

[0241] Synthesis of PANI Polymer: The PANI nanofiber was synthesized via the interfacial polymerization of aniline (FIG. 28). Distilled aniline was used for experiments. The polymerization was performed in a 20 mF glass vial. Aniline (3.2 mmol) was dissolved in 10 mF of dichloromethane to yield the organic phase. 0.8 mmol of ammonium persulfate was dissolved in 10 mF of 1 M camphorsulfonic acid solution to yield the aqueous phase. The interfacial polymerization of aniline was targeted by combining the aqueous and organic phases into a 20 mF vial. After 14 hours (o / n), the as-prepared PANLES (Emeraldine salt) was purified by filtration. PANLEB (Emeraldine base) form was obtained by reduction with a 0.1 M aq. NH4OH solution. FIG. 28 shows Fourier-transform infrared spectra of PANLEB nanofibers. The FTIR spectrum displays quinoid ring (Q) stretching at 1576 cm'1, benzenoid ring (B) stretching at 1491 cm'1, C-N stretching vibration near quinone diimine unit at 1378 cm'1, C-N stretching in cA-Q-B-Q, Q-B-B and B-B-Q at 1295 cm'1, C-N stretching in B-B-B at 1224 cm'1, aromatic C-H in-plane bending vibration at 1144 cm'1, aromatic C-H out of plane bending vibration of 1,2,4-ring at 806 cm'1.

[0242] Preparation of Ink and Coating: The PANI dispersion was obtained by mixing 30 mg of PANLEB powder and 1.5 mF of D. I. water and sonicating for 1 hour. Sonication treatment was processed to redisperse polyanilines into the original nanoscale fibers. The fluorous surfactant solution was prepared by dissolving 100 mg of Krytox-PEG-600- diamide (KPD) in 2 mL of hexafluoroisopropanol (HFIP), which is miscible with water. The fluorous PANI (F-PANI) dispersion was obtained by sonicating 600 pL of polymer dispersion and 100 pL of fluorous surfactant solution for 30 minutes. In this process, the noncovalent interactions between KPD (amide and ether groups) and the imines of the PANI nanofibers are introduced.

[0243] Polymer coatings were prepared by fabricating PANI inks onto the substrates (nitrocellulose membrane or filter paper). Test line bands with an area of 45 mm2(1.5 cm * 0.3 cm) were created using 17 pL of ink, while bands measuring 105 mm2(1.5 cm * 0.7 cm) and 210 mm2(1.5 cm * 1.4 cm) were created using 40 pL and 80 pL of ink, respectively. The thickness of the test line bands was obtained by the stylus profilometer, and the average value was 27.9 ± 5.9 pm (n = 5). The test lines were used for measurement after drying for 2 hours.

[0244] Calculation of conductivity of the coating: The conductivity was calculated by using the four-point probe method. The resistance reading ( / ?) and a constant (C = 4.3947) derived from the dimensions of the sample were recorded, and the sheet resistance (ps) was determined using the following equation ps= R * C I O' = -

[0245] Ps*1

[0246] The resistivity of the coating is psmultiplied by its thickness (Z), and the conductivity (cr) is its reciprocal. The resistance ( / ?) values were collected from over 30 different locations with 3 samples for each concentration.

[0247] EXAMPLE 3

[0248] The following example describes the synthesis and characterization of conducting polymers.

[0249] Procedure for the Synthesis of ANI-F Monomers: Perfluorinated aniline monomers were generally synthesized via nucleophilic aromatic substitution reactions with a perfluorinated alcohol to yield 2-perfluoro alkoxy 1 -nitrobenzene. Following this, the nitro-moiety was reduced to the aniline form via a tin(II) chloride reduction. See FIG. 30. General Procedure for Perfluoroalkoxy-Substituted Nitro Moieties: To a 250 mL oven-dried 3-arm round bottom flask with a reflux condenser degassed, added perfluoroalcohol (8.50 mmol) and l-fluoro-2-nitrobenzene (7.08 mmol) followed by 120 mL of anhydrous tetrahydrofuran under argon atmosphere. Then placed flask in an ice bath and slowly added potassium tert-butoxide (9.21 mmol). Heated reaction vessel to reflux and allowed reaction to proceed for 72 hours under argon atmosphere. The reaction was then cooled to room temperature. Following this, the mixture was diluted and extracted with DI water (2x200 mL) and ethyl acetate (2x200 mL). From here the organic layer was dried with magnesium sulfate, filtered, and concentrated under vacuum. The product was further purified by column chromatography on silica gel with eluent ethyl acetate / hexane (1:10) to afford the product. l-((3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)oxy)-2- nitrobenzene (Nitro-F17): ’ H NMR (600 MHz, CDCh) 5 7.85 (d, J= 8.3 Hz, 1H), 7.59 - 7.53 (t, 1H), 7.13 - 7.07 (m, 3H), 4.41 (t, J = 6.9 Hz, 5H), 2.74 (m, J= 18.3, 9.2 Hz, 3H).19F NMR (565 MHz, CDCh) 5 -80.72 (t, J= 10.2 Hz), -113.10 - -113.30 (m), -121.56 (m), -121.84 (m), -122.65 (m), -123.40 (m), -126.06 (m).13C NMR (151 MHz, CDCh) 8 151.29, 134.12, 125.76, 121.44, 117.42, 117.13, 114.72, 111.09, 110.80, 110.72, 110.22, 108.39, 61.96, 31.21. Expected m / z: 585.02327. Observed m / z: 586.06693[M+H]+. 61% yield. See FIG. 31 A. l-nitro-2-((3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)oxy)benzene (Nitro-F13): ’ H NMR (600 MHz, CDCh) 8 7.85 (d, J = 8.3 Hz, 1H), 7.56 (t, J= 7.1 Hz, 1H), 7.13 - 7.08 (m, 2H), 4.41 (t, J = 6.9 Hz, 2H), 2.74 (m, J = 18.3, 9.2 Hz, 2H).19F NMR (565 MHz, CDCh) 8 -80.75 (t, J = 10.2 Hz), -113.22 (m, J= 14.2 Hz), -121.80 (m), -122.81 (m), -123.46 (m), -126.09 (m).13C NMR (151 MHz, CDCh) 8 151.28, 140.32, 134.13, 125.72, 121.42, 117.33, 117.28, 114.71, 110.24, 108.68, 61.90, 31.08. Expected m / z: 485.02966. Observed: 486.03694 [M+H]+. 42% yield. See FIG. 31B. l-nitro-2-((3,3,4,4,5,5,6,6,6-nonafluorohexyl)oxy)benzene (Nitro-F9):1H NMR (600 MHz, CDCh) 8 7.84 (d, J = 8.4, 1.8 Hz, 1H), 7.58 - 7.52 (t, 1H), 7.09 (m, J= 8.5, 7.2 Hz, 2H), 4.41 (t, J= 6.9 Hz, 2H), 2.77 - 2.66 (m, 2H).19F NMR (565 MHz, CDCh) 8 -81.01 - -81.11 (t), -113.45 - -113.59 (m), -124.46 (m), -125.99 (m).13C NMR (151 MHz, CDCh) 8 151.28, 140.32, 134.13, 125.72, 121.42, 117.33, 117.28, 114.71, 110.24, 108.68, 61.90, 31.08. Expected m / z: 385.03605. Determined: 386.04332 [M+H]+. 58% yield. See FIG. 31C. l-nitro-2-(3,3,3-trifluoropropoxy)benzene (Nitro-F3):!H NMR (600 MHz, CDCh) 8 7.87 (d, 7= 8.0, 1.7 Hz, 1H), 7.57 (t, 7= 8.3, 7.5, 1.7 Hz, 1H), 7.15 - 7.08 (m, 2H), 4.36 (t, 7 = 6.7 Hz, 2H), 2.74 (m, 7 = 10.4, 6.7 Hz, 2H).19F NMR (565 MHz, CDCh) 5 -64.84 (t, 7 = 10.4 Hz).13C NMR (151 MHz, CDCh) 5 151.32, 134.08, 125.73, 125.56, 121.38, 114.72, 114.71, 62.81, 33.98. Expected m / z: 235.04563. Determined: 236.05247 [M+H]+. 60% yield. See FIG. 3 ID.

[0250] 1-nitro-2-(octyloxy)benzene (Nitro-H17):1H NMR (600 MHz, CDCE) 8 7.83 (dd, 7= 8.1, 1.7 Hz, 1H), 7.52 (m, 7 = 8.4, 7.4, 1.7 Hz, 1H), 7.08 (m, 7 = 8.5, 1.2 Hz, 1H), 7.02 (m, 7 = 8.3, 7.4, 1.2 Hz, 1H), 4.12 (t, 7= 6.5 Hz, 2H), 1.85 (m, 7 = 9.3, 7.9, 6.5 Hz, 2H), 1.56 - 1.46 (m, 2H), 1.41 - 1.30 (m, 7H), 0.91 (m, 7 = 7.1, 1.7 Hz, 4H).13C NMR (151 MHz, CDCh) 8 152.51, 133.94, 125.53, 119.98, 114.42, 69.66, 31.79, 29.24, 29.18, 28.96, 25.85, 22.66, 14.10. Expected m / z: 251.15214. Determined: 252.15997[M+H]+. 92% yield. See FIG. 31E.

[0251] General Procedure for Perfluoroalkoxy-Substituted Aniline Moieties: To a 100 mL oven-dried 3-arm round bottom flask with a reflux condenser degassed under Ar atmosphere, added nitro-moiety followed by tin chloride (II) dihydrate followed by 40 mL of ethanol. Upon stirring, slowly added concentrated hydrochloric acid over 5 minutes. Heated reaction vessel to reflux and allowed reaction to proceed for 24 hours under Ar atmosphere. A light orange solution was yielded, and the reaction vessel was cooled and quenched with DI water. From here, the reaction was diluted and extracted with DI water (2x150 mL) and dichloromethane (2x200 mL). Then, the organic layer was dried with magnesium sulfate, filtered, and concentrated under vacuum. The orange oil was cooled and precipitated in isopropanol to afford a light orange solid. See FIG. 32.

[0252] 2-((3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)oxy)aniline (Ani- F17): ’ H NMR (400 MHz, CDCh) 8 6.91 - 6.75 (m, 4H), 4.33 (t, 7 = 6.6 Hz, 2H), 2.68 (m, 7= 18.4, 6.8 Hz, 2H).19F NMR (565 MHz, CDCh) 8 -80.71 (t, 7 = 10.1 Hz), - 112.77 - -113.59 (m), -121.71 (m, 7= 143.0, 37.3 Hz), -122.65 (m), -123.06 - -123.81 (m), -125.88 - -126.22 (m).13C NMR (151 MHz, CDCh) 8 145.62, 136.43, 122.07, 118.44, 117.74, 117.13, 115.44, 111.61, 111.14, 110.90, 110.79, 110.74, 110.22, 108.39, 108.38, 60.36, 31.31. Expected m / z: 555.04909. Determined: 556.05637 [M+H]+. 86% yield. See FIG. 33A.

[0253] 2-((3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)oxy)aniline (ANI-F13):!H NMR (400 MHz, CDCh) 5 7.00 - 6.79 (m, 4H), 4.35 (t, J= 6.6 Hz, 2H), 2.71 (m, J= 25.4, 18.4, 6.9 Hz, 2H).19F NMR (565 MHz, CDCh) 5 -80.76 (m, J= 10.0 Hz), -113.11 - - 113.26 (m), -121.83 (m), -122.82 (m), -123.49 (m), -126.10 (m).13C NMR (151 MHz, CDCh) 5 122.06, 117.72, 117.19, 116.38, 111.71, 111.03, 110.85, 110.24, 108.45, 60.47, 31.28. Expected m / z: 455.05548. Determined: 456.06276 [M+H]+. 79% yield. See FIG. 33B.

[0254] 2-((3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)oxy)aniline (ANI-F9):1H NMR (400 MHz, CDCh) 8 6.92 - 6.65 (m, 4H), 4.35 (t, J = 6.5 Hz, 2H), 2.69 (m, J= 18.2, 6.5 Hz, 2H).19F NMR (376 MHz, CDCh) 8 -81.00 (m, J= 9.7 Hz), -113.44 (m, J= 15.6 Hz), -124.43 (m), -125.94 (m).13C NMR (151 MHz, CDCh) 8 145.98, 122.06, 119.23, 117.58, 117.36, 116.03, 115.80, 111.67, 110.33, 108.73, 60.40, 31.20. Expected m / z: 355.06187. Determined: 356.06914 [M+H]+. 78% yield. See FIG. 33C.

[0255] 2-(3,3,3-trifluoropropoxy)aniline (ANI-F3):1H NMR (600 MHz, CDCh) 8 6.87 - 6.62 (m, 4H), 4.23 (t, J = 6.3 Hz, 2H), 3.70 (s, 2H), 2.70 - 2.60 (m, 2H).19F NMR (565 MHz, CDCh) 8 -64.56 (t, J = 10.6 Hz).13C NMR (151 MHz, CDCh) 8 151.27, 140.19, 134.20, 125.71, 125.53, 121.26, 114.68, 62.69, 33.80. Expected m / z: 205.07145. Determined: 206.07873[M+H]+. 47% yield. See FIG. 33D.

[0256] 2-(octyloxy)aniline (ANI-H17):1H NMR (600 MHz, CDCh) 8 6.84 - 6.78 (m, 2H), 6.74 (m, J= 15.0, 5.9 Hz, 2H), 4.01 (t, J= 6.5 Hz, 2H), 1.87 - 1.80 (m, 2H), 1.49 (m, J= 7.2 Hz, 2H), 1.42 - 1.26 (m, 8H), 0.92 (m, J= 7.0, 2.2 Hz, 3H).13C NMR (151 MHz, CDCh) 8 120.83, 111.67, 68.50, 31.84, 29.37, 29.28, 29.25, 26.07, 22.66, 14.11. Expected m / z: 221.117796. Determined: 222.18524 [M+H]+. 73% yield. See FIG. 33E.

[0257] General Procedure for PANI-F Polymers: A library of PANI-F materials were synthesized via the interfacial oxidative polymerization of 5 ANI-F motifs. First, perfluroalkoxy aniline (0.904 mmol) were solvated in 20 mF of dichloromethane in a 40 mF vial. Then, ammonium persulfate (3.61 mmol) was dissolved in 20 mF of 1 M hydrochloric acid to yield the aqueous phase in a 20 mF vial. Following this, the aqueous phase was added to the organic phase in a 40 mF vial. The polymerization proceeded under room temperature conditions, stirred for 24 hours to afford a dark black organic phase. From here, the dark black material was rinsed with DI water and filtered, followed by treatment with IM sodium hydroxide to yield the emeraldine base. The dark polymer powder was further rinsed with DI water and dried under vacuum at 60° C to afford the product. The material was further characterized via Fourier-transform infrared spectroscopy. See FIG. 34.

[0258] Synthesis of PANI-F17: FTIR spectra reveals quinoid stretch at 1623 cm'1, benzoid stretch at 1500 cm'1, 1198 cm'1C-N stretch, 1143.599 cm'1C-N stretch, 750.1864 cm'1C-H out of plane bending vibration. 79% yield.

[0259] Synthesis of PANI-13: FTIR spectra reveals quinoid stretch at 1623 cm'1, benzoid stretch at 1498 cm'1, 1189 cm'1C-N stretch, 1134 cm'1C-N stretch, 756 cm'1C- H out of plane bending vibration. 56% yield.

[0260] Synthesis of PANI-F9: FTIR spectra reveals quinoid stretch at 1601 cm'1, benzoid stretch at 1518cm'1, 1211 cm'1C-N stretch, 1130 cm'1C-N stretch, 750 cm'1C- H out of plane bending vibration. 62% yield.

[0261] Synthesis of PANI-F3: FTIR spectra reveals quinoid stretch at 1589 cm'1, benzoid stretch at 1508 cm'1, 1195 cm'1C-N stretch, 1105 cm'1C-N stretch, 746 cm'1C- H out of plane bending vibration. 38% yield.

[0262] Synthesis of PANI-H17: FTIR spectra reveals quinoid stretch at 1497 cm'1, benzoid stretch at 1459 cm'1, 1203 cm'1C-N stretch, 1161 cm'1C-N stretch, 748 cm'1C- H out of plane bending vibration. 50% yield.

[0263] General Procedure for Perfluoroalkoxy-Substituted Aniline Dimer Moieties: FIG. 35 shows the synthesis of Aniline dimers proceeds via Buchwald Hartwig followed by a b2pin2 reduction.

[0264] Al-(2-((3,3,4,4,5,5,6,6,7 ,7 ,8,8,9,9,10,10,10- heptadecafluorodecyl)oxy)phenyl)benzene-l,4-diamine (ANI-F17 Dimer): ’ H NMR (600 MHz, CDCh) 5 7.01 (dd, J = 30.3, 5.1 Hz, 1H), 6.86 (m, 1H), 6.80 - 6.69 (m, 1H), 4.40 (m, 1H), 3.61 (s, 1H), 2.83 - 2.63 (m, 1H).19F NMR (565 MHz, Acetone) 5 -81.63 (t, J = 10.1 Hz), -113.31 - -113.63 (m), -122.24 (m, J= 156.0 Hz), -123.21 (m), -123.96 (m), -126.68 (m).13C NMR (151 MHz, CDCh) 5 145.43, 142.36, 136.17, 133.19, 124.13, 121.94, 117.89, 117.76, 117.14, 116.11, 112.54, 111.24, 111.15, 110.90, 110.74, 110.22, 108.40, 60.51, 31.33. Expected m / z: 646.09129. Determined: 647.09857 [M+H]+. 52% yield. See FIG. 36A.

[0265] 2-((3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)oxy)-A-(4- nitrophenyl) aniline (Nitro-F17 Dimer):!H NMR (600 MHz, CDCh) 8 8.17 (d, J = 9.2 Hz, 2H), 7.45 (dd, 7= 7.8, 1.6 Hz, 1H), 7.11 (m, 7 = 7.8, 1.6 Hz, 1H), 7.09 - 7.03 (m, 3H), 6.99 (dd, 7 = 8.1, 1.4 Hz, 1H), 6.48 (s, 1H), 4.40 (t, 7 = 6.3 Hz, 2H), 2.75 - 2.62 (m, 2H).19F NMR (565 MHz, CDCh) 8 -80.70 (t, 7 = 10.0 Hz), -112.89 - -113.09 (m), - 121.52 (m), -121.83 (m), -122.65 (m), -123.33 (m), -126.04 (m).13C NMR (151 MHz, CDCh) 8 149.35, 148.74, 140.15, 129.50, 126.12, 123.92, 121.85, 119.78, 117.72, 117.12, 114.39, 112.22, 111.12, 110.86, 110.77, 110.72, 110.22, 108.39, 60.78, 31.18. Expected m / z: 676.32985. Determined: 677.07275 [M+H]+. 55% yield. See FIG. 36B.

[0266] A7-(2-((3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)oxy)phenyl)benzene-l,4- diamine (ANI-F13 Dimer): ’ H NMR (600 MHz, CDCh) 8 7.17 - 7.07 (m, 3H), 7.03 (d, J = 8.3 Hz, 2H), 6.98 - 6.80 (m, 3H), 5.98 (s, 1H), 4.39 (t, J = 6.5 Hz, 2H), 2.71 (m, J = 24.9, 18.3, 6.6 Hz, 2H).19F NMR (565 MHz, CDCh) 8 -80.74 (t, 7= 10.1 Hz), -113.10 (m, 7= 16.0 Hz), -121.77 (m), -122.80 (m), -123.43 (m), -126.08 (m).13C NMR (151 MHz, CDCh) 8 145.43, 142.36, 136.17, 133.19, 124.13, 117.19, 117.76, 117.14, 116.11, 112.54, 111.24, 110.90, 110.74, 110.22, 108.40, 60.51, 31.33. Expected m / z: 546.33224. Determined: 547.10496 [M+H]+. 50% yield. See FIG. 36C.

[0267] A1-(2-((3,3,4,4,5,5,6,6,6-nonafluorohexyl)oxy)phenyl)benzene-l,4-diamine (ANI-F9 Dimer): ’ H NMR (600 MHz, CDCh) 8 7.01 (dd, 7= 27.6, 5.5 Hz, 3H), 6.87 (m, 7= 4.2 Hz, 2H), 6.74 (dd, 7= 23.6, 6.4 Hz, 3H), 5.86 (s, 1H), 4.44 - 4.36 (m, 2H), 3.73 (s, 2H), 2.77 - 2.60 (m, 2H).19F NMR (565 MHz, CDCh) 8 -80.98 (t, 7 = 9.9 Hz), -113.35 (m, 7 = 16.0 Hz), -124.38 (m), -125.90 (m).13C NMR (151 MHz, CDCh) 8 145.44, 142.14, 136.13, 133.31, 124.07, 121.94, 117.93, 117.61, 117.37, 116.22, 112.58, 111.25, 110.35, 108.74, 60.49, 31.23, 24.59. Expected m / z: 446.31663. Determined: 447.11134 [M+H]+. 52% yield. See FIG. 36D.

[0268] Af / -(2-(3,3,3-trifluoropropoxy)phcnyl)bcnzcnc- 1 ,4-diaminc (ANI-F3 Dimer): ’ H NMR (600 MHz, CDCh) 8 7.19 - 6.96 (m, 4H), 6.95 - 6.72 (m, 5H), 5.93 (s, 1H), 4.30 (t, J = 6.3 Hz, 2H), 2.76 - 2.63 (m, 2H).19F NMR (565 MHz, CDCh) 8 -64.49 (t, 7 = 10.5 Hz).13C NMR (151 MHz, CDCh) 8 126.02, 121.89, 83.19, 75.06, 61.45, 24.87, 24.57. Expected m / z: 296.29321. Determined: 297.12092 [M+H]+. 48% yield. See FIG. 36E.

[0269] N1-(2-(octyloxy)phenyl)benzene-l,4-diamine (ANI-H17 Dimer):!H NMR (600 MHz, CDCE) 5 7.10 - 6.97 (m, 3H), 6.87 - 6.71 (m, 5H), 5.96 (s, 1H), 4.05 (t, J = 6.6 Hz, 2H), 1.54 - 1.46 (m, 2H), 1.44 - 1.21 (m, 10H), 0.91 (t, J = 6.9 Hz, 3H).13C NMR (151 MHz, CDCE) 5 146.67, 140.18, 135.56, 134.63, 123.41, 120.78, 118.22, 116.88, 112.44, 111.20, 68.49, 31.84, 29.40, 29.38, 29.26, 26.19, 25.04, 22.67, 14.12. Expected m / z: 312.22016. Determined: 313.22744 [M+H]+. 41% yield.

[0270] General Procedure for PANI-F Copolymers: FIG. 37 shows the synthesis of PANI-F copolymers via interfacial oxidative polymerization with ammonium persulfate followed by a potassium hydroxide reduction. FIG. 38 shows images of PANI-F copolymerization between 5 minute and 24 hour time stamps.

[0271] A library of PANI-F copolymer materials were synthesized via the interfacial oxidative polymerization of 5 ANI-F motifs. First, perfluroalkoxy aniline dimer (0.904 mmol) were solvated in 20 mF of dichloromethane in a 40 mF vial. Then, ammonium persulfate (3.61 mmol) was dissolved in 20 mF of 1 M hydrochloric acid to yield the aqueous phase in a 20 mF vial. Following this, the aqueous phase was added to the organic phase in a 40 mF vial. The polymerization proceeded under room temperature conditions, stirred for 24 hours to afford a dark black organic phase. From here, the dark black material was rinsed with DI water and filtered, followed by treatment with IM sodium hydroxide to yield the emeraldine base. The dark blue polymer powder was further rinsed with DI water and dried under vacuum at 60° C to afford the product. The material was further characterized via Fourier-transform infrared spectroscopy.

[0272] Synthesis of PANI-F17 Copolymer: ’ H NMR (600 MHz, Acetone) 5 8.04 - 6.34 (m, 4H), 4.47 (s, 2H).19F NMR (565 MHz, Acetone) 5 -81.62 (t, J = 10.4 Hz), -113.50 (m, J = 18.1 Hz), -113.67 (m), -122.26 (m, J = 154.2 Hz), -123.23 (m), -123.95 (m), - 126.69 (m). FTIR spectra reveals quinoid stretch at 1594 cm'1, benzoid stretch at 1506 cm'1, 1195 cm'1C-N stretch, 1143 cm'1C-N stretch, 746 cm'1C-H out of plane bending vibration. 80% yield.

[0273] Synthesis of PANI-13 Copolymer: FTIR spectra reveals quinoid stretch at 1594 cm'1, 1508 cm'1benzoid stretch, 1180 cm'1C-N stretch, 1139 cm'1C-N stretch, 746 cm'1C-H out of plane bending vibration. 85% yield. Synthesis of PANI-F9 Copolymer: FTIR spectra reveals quinoid stretch at 1592 cm'1, 1502 cm'1benzoid stretch, 1220 cm'1C-N stretch, 1130 cm'1C-N stretch, 748 cm'1C-H out of plane bending vibration. 62% yield.

[0274] Synthesis of PANI-F3 Copolymer: FTIR spectra reveals quinoid stretch at 1600 cm'1, 1506 cm'1benzoid stretch, 1197 cm'1C-N stretch, 1132 cm'1C-N stretch, 742 cm'1C-H out of plane bending vibration. 36% yield.

[0275] Synthesis of PANI-H17 Copolymer: FTIR spectra reveals quinoid stretch at 1521 cm'1, 1479 cm'1benzoid stretch, 1193 cm'1C-N stretch, 1133 cm'1C-N stretch, 771 cm'1C-H out of plane bending vibration. 67% yield.

[0276] It should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific implementations described above. The specific implementations described above are disclosed as examples only. While several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and / or structures for performing the functions and / or obtaining the results and / or one or more of the advantages described herein, and each of such variations and / or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and / or configurations will depend upon the specific application or applications for which the teachings of the present invention is / are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, and / or methods, if such features, systems, articles, materials, and / or methods are not mutually inconsistent, is included within the scope of the present invention. The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”

[0277] The phrase “and / or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, a reference to “A and / or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0278] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e., “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0279] As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and / or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0280] In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of’ and “consisting essentially of’ shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

Claims

CLAIMSWhat is claimed is:

1. A composition, comprising: a conducting polymer comprising at least one fluorine-containing moiety, wherein the composition is configured such that the composition displays an increase in conductivity in response to a presence of a fluoroalkyl analyte.

2. A composition, comprising: a conducting polymer; and an additive comprising at least one fluorine-containing moiety, wherein the composition is configured such that the composition displays an increase in conductivity in response to a presence of a fluoroalkyl analyte.

3. The composition of any one of claims 1-2, wherein the at least one fluorine- containing moiety is a fluoroalkyl-containing moiety.

4. The composition of any one of claims 1-3, wherein the conducting polymer comprises poly aniline, polypyrrole, poly thiophene, poly arylene vinylene, poly (3,4- ethylenedioxy thiophene), polyacetylene, polyarylene, and / or combinations thereof.

5. The composition of any one of claims 1-4, wherein the fluoroalkyl analyte is a perfluoroalkyl substance and / or a polyfluoroalkyl substance.

6. The composition of any one of claims 1-5, wherein the increase in conductivity is an increase by a factor of at least 1000.

7. The composition of any one of claims 1-6, wherein the composition is configured to absorb the fluoroalkyl analyte.

8. The composition of any one of claims 1-7, wherein the fluoroalkyl analyte is configured to cause a reaction that results in an oxidation of the conducting polymer.

9. The composition of any one of claims 1-8, wherein the fluoroalkyl analyte is configured to protonate the conducting polymer.

10. The composition of any one of claims 1-9, wherein the fluoroalkyl analyte is a Brpnstcd acid.

11. The composition of any one of claims 1-10, wherein the conducting polymer is part of a composite structure, the composite structure comprising cellulose, one or more polymers, carbon nanotubes, graphene, graphite, and / or a metal.

12. The composition of any one of claims 1-11, wherein the conducting polymer is configured to absorb the fluoroalkyl analyte more strongly at a first level of oxidation and less strongly at a second state of oxidation.

13. An article, comprising: the composition of any one of claims 1-12.

14. The article of claim 13, wherein the article comprises a substrate and the composition is deposited on at least a portion of the substrate.

15. The article of any one of claims 13-14, wherein the article is a lateral flow assay device.

16. The article of any one of claims 13-14, wherein the article is a membrane and / or a filter.

17. The article of claim 16, wherein the membrane and / or the filter is patterned with multiple materials.

18. The article of any one of claims 13-17, wherein the article is configured as a sensor.

19. The article of any one of claims 13-18, wherein the article is configured such that the article is powered wirelessly.

20. The article of any one of claims 13-19, wherein the article is configured such that the increase in conductivity in response to the presence of the fluoroalkyl analyte is determined wirelessly.

21. The article of claim 20, wherein the increase in conductivity in response to the presence of the fluoroalkyl analyte is determined wirelessly by a smartphone.

22. The article of any one of claims 13-21, wherein the article comprises at least one passive RFID device.

23. A method, comprising: exposing the composition of any one of claims 1-12 or the article of any one of claims 13-22 to a fluid suspected of comprising the fluoroalkyl analyte; and detecting the increase in conductivity in response to a presence of the fluoroalkyl analyte.

24. The method of claim 23, wherein the fluid comprises at least one liquid.

25. The method of claim 24, wherein the fluid comprises water.

26. The method of claim 25, wherein the water is sourced from a home, a well, an industrial waste stream, a contaminated site, a concentrator system, and / or a landfill.

27. The method of any one of claims 24-26, wherein the fluid comprises at least one organic solvent.

28. The method of claim 23, wherein the fluid comprises water and at least one organic solvent.

29. A sensor, comprising:a conducting material comprising at least one fluorine-containing moiety, wherein the conducting material is configured such that the sensor displays a change in conductivity in response to a presence of a fluoroalkyl analyte.

30. A sensor, comprising: a conducting material; and an additive comprising at least one fluorine-containing moiety, wherein the conducting material is configured such that the sensor displays a change in conductivity in response to a presence of a fluoroalkyl analyte.

31. The sensor of any one of claims 29-30, wherein the at least one fluorine- containing moiety is a fluoroalkyl-containing moiety.

32. The sensor of any of claims 29-31, wherein the conducting material comprises a conducting polymer.

33. The sensor of any one of claims 29-32, wherein the fluoroalkyl analyte is a perfluoroalkyl substance and / or a polyfluoroalkyl substance.

34. A composition, comprising: a material comprising at least one fluorine-containing moiety, and having a first solubility, wherein the material is configured to interact with a fluoroalkyl analyte to form a conjugate material comprising the fluoroalkyl analyte, and wherein the conjugate material, in response to a stimulus, has a second solubility that is less than the first solubility.

35. The composition of claim 34, wherein the at least one fluorine-containing moiety is a fluoroalkyl-containing moiety.

36. The composition of any one of claims claim 34-35, wherein the material comprises a polymer.

37. The composition of claim 36, wherein the conjugate material is a polymerfluoroalkyl analyte conjugate.

38. The composition of any one of claims 36-37, wherein the polymer comprises repeating ethylene glycol units, each ethylene glycol unit comprising one or more fluorine-containing moieties.

39. The composition of any one of claims 34-38, wherein the stimulus is an increase in temperature.

40. The composition of any one of claims 34-39, wherein the stimulus is an increase from less than or equal to room temperature to a temperature greater than or equal to 70 °C.

41. The composition of any one of claims 36-37, wherein the polymer comprises a basic moiety.

42. The composition of claim 41, wherein the basic moiety is a positively charged moiety.

43. The composition of any one of claims 41-42, wherein the basic moiety is a positively charged amine.

44. The composition of any one of claims 41-43, wherein the stimulus is an increase in solution pH.

45. The composition of any one of claims 34-44, wherein the stimulus is a first stimulus, and wherein the conjugate material is configured to release the fluoroalkyl analyte in response to a second stimulus.

46. The composition of claim 45, wherein the second stimulus is a decrease in temperature.

47. The composition of any one of claims 45-46, wherein the second stimulus is a decrease from a temperature greater than or equal to 70 °C to less than or equal to room temperature.

48. The composition of claim 45, wherein the second stimulus is a decrease in solution pH.

49. A method, comprising: exposing a material comprising at least one fluorine-containing moiety to a sample suspected of comprising a fluoroalkyl analyte, thereby forming a conjugate material comprising the fluoroalkyl analyte, if present; and exposing the conjugate material comprising the fluoroalkyl analyte, if present, to a sensor configured to detect the fluoroalkyl analyte.

50. The method of claim 49, further comprising, prior to exposing the conjugate material comprising the fluoroalkyl analyte, if present, to the sensor, applying a stimulus to precipitate and / or aggregate the conjugate material comprising the fluoroalkyl analyte, if present, in the sample.

51. The method of claim 50, further comprising, after exposing the conjugate material comprising the fluoroalkyl analyte, if present, to the sensor, applying a second stimulus to release the fluoroalkyl analyte, if present, from the conjugate material comprising the fluoroalkyl analyte, if present.

52. The method of any one of claims 49-51, further comprising detecting the fluoroalkyl analyte, if present, using the sensor.

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