# US 10,371,688 B2 · Sensing system based on a fluorophore array > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,371,688 B2 - Document ID: US10371688B2 - Status: Granted - Kind: B2 - Application number: 15/430,320 - Filed: 2017-02-10 - Published: 2017-08-10 - Granted: 2019-08-06 - Earliest claimed: 2016-02-10 - Applicants: Rhode Island Board of Education, State of Rhode Island and Providence Plantations - Inventors: William B. Euler - Web page: https://patentgrep.com/patent/US10371688B2 ## CPC - G01N 33/227: {Explosives, e.g. combustive properties thereof} - G01N 21/643: {non-biological material} - G01N 33/0057: {Warfare agents or explosives} - G01N 2021/6432: {Quenching} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A sensing system for explosives is provided. The sensor is based on a layered structure of approximately a monolayer of a fluorophore deposited onto a few nm of a transparent polymer, supported by a substrate. The fluorophores can be xanthene laser dyes, which have high quantum yields, and the polymers can be commodity materials polymethylmethacrylate and polyvinylidene difluoride. The different fluorophore/polymer combinations give different emission responses to analytes, including both signal quenching and enhancement. The pattern of responses can be used to identify the analyte. The common explosives TNT, PETN, RDX, HMX, and TATP as gas phase species can all be uniquely identified at room temperature using only the natural vapor pressure of the explosive to deliver sample to the sensor. ## Claims ### Claim 1 A sensing system for identifying an analyte, the system comprising: a light source, an optical detecting system, and an array of sensors each supported on a substrate, each sensor comprising (a) a top layer comprising a fluorophore, and (b) an intermediate layer in between the top layer and the substrate for amplifying an optical response from the fluorophore, wherein the intermediate layer is between 100 nm and 1000 nm in thickness, consists essentially of one or more polymers and has a refractive index less than that of the fluorophore, and wherein at least two sensors in the array have respective intermediate layers that differ in thickness, such that when the light source is activated in the presence of an analyte in its gas phase, the optical detecting system would detect altered optical responses from the at least two sensors indicating signal quenching by at least 10% from one sensor and emission enhancement by at least 10% from the other sensor, thereby generating a fluorescent pattern for identifying the analyte by comparing the pattern to one or more target chemicals and wherein the substrate comprises a material selected from the group consisting of glass, flat silicon, porous silicon, and a polymer different from the intermediate layer. ### Claim 2 (depends on 1) The system of claim 1, wherein the intermediate layer is transparent. ### Claim 3 (depends on 1) The system of claim 1, wherein the one or more polymers are selected from the group consisting of polymethylmethacrylate (PMMA), polyvinylidene difluoride (PVDF), poly(vinylidene difluoride-co-trifluoroethylene), polypropylene, polyisobutylene and polystyrene (PS). ### Claim 4 (depends on 1) The system of claim 1, wherein the average refractive index of the fluorophores in each pixel is no less than about 1.60. ### Claim 5 (depends on 1) The system of claim 1, wherein the fluorophore comprises a xanthene dye. ### Claim 6 (depends on 1) The system of claim 1, wherein the fluorophore has high quantum yield that is no less than 0.20. ### Claim 7 (depends on 1) The system of claim 1, wherein the intermediate layer is more than about 250 nm thick. ### Claim 8 (depends on 1) The system of claim 1, wherein the intermediate layer is less than about 800 nm thick. ### Claim 9 (depends on 1) The system of claim 1, wherein the optical detecting system comprises a spectrometer or a CCD camera. ### Claim 10 (depends on 1) The system of claim 1, wherein the optical detecting system comprises an optical filter. ### Claim 11 (depends on 1) The system of claim 1, further comprising a processor. ### Claim 12 (depends on 11) The system of claim 11, wherein the processor, based on expected spectral response from a target explosive or related material, determines if the target is in the analyte. ### Claim 13 (depends on 11) The system of claim 11, wherein the target explosive or related material is selected from the group consisting of TNT, TNB, PETN, RDX, HMX, TATP, 2,3-DNT, 2,4-DNT, 2,6-DNT, 3,4-DNT and 4-NT. ### Claim 14 (depends on 11) The system of claim 11, wherein the processor, categorizes optical responses from all sensors into one of three values based on a preselected threshold in detected changes in fluorescence intensity: enhancement, quenching, and no change. ### Claim 15 (depends on 14) The system of claim 14, wherein the threshold is about 20%. ### Claim 16 A method for detecting an explosive or related material, the method comprising: (a). providing a fluorophore-based sensing system that comprises an array of sensors each supported on a non-metal substrate, each sensor comprising (i) a top layer comprising a fluorophore, and (ii) an intermediate layer consisting essentially of one or more polymers, more than 100 nm thick, and disposed in between the top layer and the substrate in each sensor, wherein the array of sensors are pre-selected with different fluorophore/polymer combinations among them so that optical responses from some or all sensors will be altered and result in signal quenching by at least 10% in at least one sensor and emission enhancement by at least 10% in at least another sensor in the presence of a target explosive or related material in a gas phase; (b). exposing the sensing system to an analyte-containing sample; (c). detecting altered optical responses from each sensor; (d). comparing detected optical responses to a pattern known to come from a target explosive or related material; and (e). determining whether they are similar enough to identify the analyte as the target explosive or related material. ### Claim 17 (depends on 16) The method of claim 16, wherein the explosive is selected from the group consisting of nitroaromatics, nitroamines, organic nitramides, and organic nitrates. ### Claim 18 (depends on 16) The method of claim 16, wherein the explosive or related material is selected from the group consisting of TNT, TNB, PETN, RDX, HMX, TATP, 2,3-DNT, 2,4-DNT, 2,6-DNT, 3,4-DNT and 4-NT. ### Claim 19 (depends on 16) The method of claim 16, wherein the one or more polymers are selected from the group consisting of polymethylmethacrylate (PMMA), polyvinylidene difluoride (PVDF), poly(vinylidene difluoride-co-trifluoroethylene), polypropylene, polyisobutylene and polystyrene (PS). ### Claim 20 (depends on 16) The method of claim 16, wherein the different fluorophore/polymer combinations among sensors result from at least one variables selected from the group consisting of makeup of the fluorophore, makeup of the polymer, and thickness of the intermediate polymer layer. ### Claim 21 A sensing system for detecting an explosive in a gas phase, the system comprising an array of sensors each supported on a non-metal substrate, each sensor comprising (a) a top layer comprising a fluorophore, and (b) an intermediate layer in between the top layer and the substrate for amplifying an optical response from the fluorophore, wherein the intermediate layer consists essentially of one or more polymers selected from the group consisting of polymethylmethacrylate (PMMA), polyvinylidene difluoride (PVDF), poly(vinylidene difluoride-co-trifluoroethylene), polypropylene, polyisobutylene and polystyrene (PS), is more than 100 nm thick and has a refractive index less than that of the fluorophore, and wherein each sensor in the array is different from each of the remaining sensors in at least one of three aspects: thickness of its intermediate layer, makeup of the polymers in its intermediate layer or the makeup of the fluorophore. ### Claim 22 (depends on 21) The system of claim 21, wherein the fluorophore comprises a xanthene dye. ### Claim 23 (depends on 1) The system of claim 1, wherein the intermediate layer is more than about 350 nm thick. ### Claim 24 (depends on 1) The system of claim 1, wherein at least two sensors in the array have respective intermediate layers that differ in the makeup of their polymers.