U.S. patent application number 16/673303 was filed with the patent office on 2020-06-04 for chemical sensing device.
The applicant listed for this patent is Triton Systems, Inc.. Invention is credited to James BURGESS, Leonid KRASNOBAEV, Tyson LAWRENCE, Ken MAHMUD, Aniruddha WELING.
Application Number | 20200173892 16/673303 |
Document ID | / |
Family ID | 53042289 |
Filed Date | 2020-06-04 |
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United States Patent
Application |
20200173892 |
Kind Code |
A1 |
WELING; Aniruddha ; et
al. |
June 4, 2020 |
CHEMICAL SENSING DEVICE
Abstract
A chemical sensing system includes a substrate material, a
detector capable of indicating a presence of a target compound,
gas, or vapor, and a heater for rapidly releasing compounds, gases
and vapors from the substrate material. The substrate material acts
to concentrate the compounds, gases, and vapors from a sample area
for improved detection by the detector.
Inventors: |
WELING; Aniruddha;
(Framingham, MA) ; LAWRENCE; Tyson; (Cambridge,
MA) ; MAHMUD; Ken; (Sudbury, MA) ; BURGESS;
James; (Ringgold, GA) ; KRASNOBAEV; Leonid;
(Framingham, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Triton Systems, Inc. |
Chelmsford |
MA |
US |
|
|
Family ID: |
53042289 |
Appl. No.: |
16/673303 |
Filed: |
November 4, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14452398 |
Aug 5, 2014 |
10466149 |
|
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16673303 |
|
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61862250 |
Aug 5, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 33/0057 20130101;
Y10T 436/25875 20150115; G01N 1/405 20130101; G01N 1/44 20130101;
Y10T 436/173076 20150115 |
International
Class: |
G01N 1/40 20060101
G01N001/40; G01N 33/00 20060101 G01N033/00 |
Goverment Interests
GOVERNMENT INTEREST
[0002] This invention was made with Government support under
Contract No. W911S6-10-C-0011 awarded by the U.S. Army. This
invention was also made with Government support under Contract No.
D11PC20126 awarded by the U.S. Department of the Interior, NBC
Acquisition Services Directorate. The Government has certain rights
in this invention.
Claims
1. A preconcentrator comprising a cartridge and a substrate having
a resistivity of about 10.sup.5 ohm-meters (.OMEGA.m) to about
10.sup.-7 .OMEGA.m enclosed within the cartridge.
2. The preconcentrator of claim 1, wherein the substrate is
selected from the group consisting of metal fiber, woven metal
fibers, non-woven metal fibers, porous metal, sheet metal, metal
coated glass, metal coated plastic, metal coated ceramic,
carbonaceous material, graphite, charcoal, activated carbon,
activated carbon cloth, and combinations thereof.
3. The preconcentrator of claim 1, wherein the substrate has a
magnetic permeability of greater than about 1.times.10.sup.-4 H/m,
relative permeability of greater than 100, or combinations
thereof.
4. The preconcentrator of claim 1, wherein the substrate has an
electrical resistivity of greater than 10.sup.3 .OMEGA.m.
5. The preconcentrator of claim 1, wherein the cartridge further
comprises at least a first reversibly sealable opening on one side
of the cartridge and at least a second reversibly sealable opening
on the opposite side of the cartridge.
6. A method for detecting a chemical comprising: collecting
particles and gases in a preconcentrator comprising a cartridge and
a substrate having a resistivity of about 10.sup.5 ohm-meters
(.OMEGA.m) to about 10.sup.-7 .OMEGA.m enclosed within the
cartridge; heating the substrate to release the particles and
gases; and detecting the chemical.
7. The method of claim 6, wherein the substrate has a magnetic
permeability of greater than about 1.times.10.sup.-4 H/m, relative
permeability of greater than 100, or combinations thereof.
8. The method of claim 6, wherein heating is carried out to about
200.degree. C. to about 350.degree. C.
9. The method of claim 6, wherein the heating is inductive
heating.
10. The method of claim 9, wherein inductive heater is carried out
at a frequency of about 100 kHz to about 10 MHz.
11. A sample collector comprising: a sample collector housing
having a preconcentrator holder sized to reversibly receive a
preconcentrator; and an air suction pump operably connected to the
sample collector housing and configured to produce air flow through
the preconcentrator.
12. The sample collector of claim 11, further comprising a pulsed
air nozzle connected to the sample collector housing.
13. The sample collector of claim 11, further comprising an air
compressor operably connected to the sample collector housing and
is configured to expel air from the pulsed air nozzle and direct
the expelled air toward a sample collection area.
14. The sample collector of claim 11, wherein the air suction pump
provides a flow of 1 m.sup.3/min to 10 m.sup.3/min.
15. A system comprising: a sample collector comprising: a sample
collector housing having a preconcentrator holder sized to
reversibly receive a preconcentrator; a detector comprising: a
detector housing having an detector access port sized to reversibly
receive the preconcentrator; an induction heater contained within
the detector housing, the induction heater configured to heat the
preconcentrator; and a sensing system connected to the access port
and positioned to receive desorbed gases from the preconcentrator
when the preconcentrator is received by the detector.
16. The system of claim 15, further comprising an air suction pump
operably connected to the sample collection housing and configured
to produce air flow through the preconcentrator.
17. The system of claim 16, wherein the air suction pump provides a
flow of 1 m.sup.3/min to 10 m.sup.3/min.
18. The system of claim 15, wherein the sample collector further
comprises a pulsed air nozzle connected to the sample collector
housing.
19. The system of claim 18, further comprising an air compressor
operably connected to the sample collector housing and configured
to expel air from the pulsed air nozzle and direct the expelled air
toward a sample collection area.
20. The system of claim 15, wherein preconcentrator comprises a
cartridge and a substrate having a resistivity of about 10.sup.5
ohm-meters (.OMEGA.m) to about 10.sup.-7 .OMEGA.m enclosed within
the cartridge.
21. The system of claim 15, wherein the detector comprises a
temperature feedback that limits the temperature to about
200.degree. C. to about 350.degree. C.
22. The system of claim 15, wherein the detector further comprises
a compressor operably connected to the detector access port and
configured to generate a differential pressure across the
preconcentrator when the preconcentrator is received by the
detector.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/452,398 filed Aug. 5, 2014, which claims
priority to U.S. Provisional Application No. 61/862,250 filed Aug.
5, 2013, which is hereby incorporated by reference in its
entirety.
SUMMARY
[0003] The ability to detect trace amounts of volatile organic
compounds is often required for chemical sensors such as warfare
gas stimulants, explosives, and volatile organic compounds in mouth
breath, etc.
[0004] Embodiments are directed to preconcentrators including a
cartridge having a hollow body sized to contain a substrate
enclosed within the cartridge. In some embodiments, the substrate
may be metal fiber, woven metal fibers, non-woven metal fibers,
porous metal, sheet metal, metal coated glass, metal coated
plastic, metal coated ceramic, carbonaceous material, graphite,
charcoal, activated carbon, activated carbon cloth, and
combinations thereof. In certain embodiments, the substrate may
have resistivity of about 10.sup.5 ohm-meters (.OMEGA.m) to about
10.sup.-7 .OMEGA.m, magnetic permeability of greater than about
1.times.10.sup.-4 H/m, relative permeability of greater than 100,
or combinations thereof In particular embodiments, the substrate
may have an electrical resistivity of greater than 10.sup.3
.OMEGA.m. In certain embodiments, the cartridge may include at
least a first reversibly sealable opening on one side of the
cartridge and at least a second reversibly sealable opening on the
opposite side of the cartridge.
[0005] Other embodiments are directed to a method for detecting an
chemical including the steps of collecting particles, gases, and
vapors in a preconcentrator having a substrate having resistivity
of about 10.sup.5 ohm-meters (.OMEGA.m) to about 10.sup.-7
.OMEGA.m; heating the substrate to release the particles, gases,
and vapors; and detecting the chemical in the particles, gases, and
vapors. In some embodiments, the substrate may have magnetic
permeability of greater than about 1.times.10.sup.-4 H/m, relative
permeability of greater than 100, or combinations thereof In
certain embodiments, the heating may be inductive heating, and in
some embodiments, inductive heating is carried out at a frequency
of about 100 kHz to about 10 MHz. In particular embodiments,
heating may be carried out to about 120.degree. C. to about
300.degree. C.
[0006] Further embodiments are directed to a sample collector
including a sample collector housing having a preconcentrator
holder sized to reversibly receive a preconcentrator; and an air
suction pump operably connected to the sample collector housing and
configured to produce air flow through the preconcentrator. In some
embodiments, the sample collector may further include a pulsed air
nozzle connected to the sample collector housing, and in certain
embodiments, an air compressor may be operably connected to the
sample collector housing and configured to expel air from the
pulsed air nozzle and direct the expelled air toward a sample
collection area. In various embodiments, the air suction pump may
provide a flow of 1 m.sup.3/min to 10 m.sup.3/min. In certain
embodiments, the preconcentrator may include a substrate having
resistivity of about 10.sup.5 ohm-meters (.OMEGA.m) to about
10.sup.-7 .OMEGA.m
[0007] Additional embodiments are directed to a system including a
sample collector having a sample collector housing having a
preconcentrator holder sized to reversibly receive a
preconcentrator; and a detector including a detector housing having
an detector access port sized to reversibly receive the
preconcentrator; an induction heater contained within the detector
housing, the induction heater configured to heat the
preconcentrator; and a sensing system operably connected to the
access port and positioned to receive particles, gases, and vapors
from the preconcentrator when the preconcentrator is received by
the detector. In some embodiments, the detector my further include
an air suction pump operably connected to the access port and
configured to produce air flow through the preconcentrator, and in
some embodiments, the air suction pump may provide a flow of 1
m.sup.3/min to 10 m.sup.3/min. In certain embodiments, the
preconcentrator may include a substrate having resistivity of about
10.sup.5 ohm-meters (.OMEGA.m) to about 10.sup.-7 .OMEGA.m. In
various embodiments, the preconcentrator may include a cartridge
and a substrate having a resistivity of about 10.sup.5 ohm-meters
(.OMEGA.m) to about 10.sup.-7 .OMEGA.m enclosed within the
cartridge. in some embodiments, the detector may include a
temperature feedback that limits the temperature to about
120.degree. C. to about 300.degree. C. In particular embodiments,
the detector further comprises a compressor operably connected to
the detector access port and configured to generate a differential
pressure across the preconcentrator when the preconcentrator is
received by the detector.
BRIEF DESCRIPTION OF THE FIGURES
[0008] FIG. 1 represents a general flow diagram of operating a
sensing system according to an embodiment.
[0009] FIG. 2 depicts a general representation of a chemical
sensing system according to an embodiment.
[0010] FIG. 3 depicts a sketch of a sample collector according to
an embodiment.
[0011] FIG. 4 depicts a chemical sensing system having an induction
heater according to an embodiment.
[0012] FIG. 5 depicts a general representation of an induction
heating system.
[0013] FIG. 6 depicts a miniature trace explosives trace
preconcentrator device according to an embodiment.
[0014] FIG. 7 shows MS data for TNT vapors flash extraction after
preconcentration in dry ambient. Initial TNT vapor flow was below
detection limit (<1000 counts).
[0015] FIG. 8 shows MS data for TNT vapors flash extraction after
preconcentration in wet ambient.
[0016] FIG. 9 shows with preconcentrator substrates with TSI
coating, other coating and uncoated metal mesh were exposed to TNT
vapors for 30, 60, 90 and 120 minutes without air circulation. TNT
was extracted with a solvent and measured by GC/.mu.ECD.
[0017] FIG. 10 shows sequence of TNT vapor preconcentration and
pulsed vapor release. Preconcentrator coating shows no degradation
after heating to 250.degree. C. for a number of times (up to
25).
[0018] FIG. 11 IMS spectra of laboratory air according to an
embodiment.
[0019] FIG. 12 shows IMS spectra of DNT vapors continuously
injected into IMS detector from a syringe according to an
embodiment. The showed spectra were taken with interval of 1
sec.
[0020] FIG. 13 shows IMS spectra of nitroglycerine vapors passed
through the preconcentrator and injected into IMS detector.
[0021] FIG. 14 shows IMS spectra of previously collected DNT vapor
released within 1.8 sec of heating of preconcentrator with various
release flow rates of 50, 75, 100 and 120 ml/min.
DETAILED DESCRIPTION
[0022] Embodiments of the invention are directed to systems and
methods for chemical detecting and various components of the
systems. Some embodiments are directed to preconcentrators and the
various components of a preconcentrator collector system for
collecting and concentrating chemicals from a collection area.
Other embodiments are directed to devices including sensors and
other components capable of releasing the chemicals collected from
the collection area and sensing particular chemicals from the
collected sample. Still other embodiments using the
preconcentrators, sample collectors, and sensors, detectors and
other devices associated with these systems.
[0023] In various embodiments, the preconcentrator may be a hollow
body sized to contain a substrate capable of reversably bonding to
various chemical species. The tubular hollow body may have at least
a first reversibly sealable opening on one side of the hollow body
and at least a second reversibly sealable opening on the opposite
side of the hollow body. For example, in some embodiments, the
preconcentrator may be cylindrical cartridge with circular openings
on each end of the cylinder. In other embodiments, the
preconcentrator may be disk shaped having concave disk shaped ends
connected by a broad cylindrical body providing a substantially
obround hollow body. Openings may be provided on any surface of the
disk shaped body.
[0024] The reversible sealable openings on the preconcentrator may
be created by any means. For example, in certain embodiments, the
reversible seal may be removable caps, stoppers, corks, plastic
films, or combinations thereof In other embodiments, the reversible
seals may be integral to the cartridge. For example, the openings
may be sealed using hinged covers or slide covers that can be moved
to allow access to the internal hollow body of the cartridge during
use and then resealed after the sample has been obtained. In still
other embodiments, the openings may be sealed using both integral
hinged or slide covers and removable caps or plastic films.
[0025] Certain embodiments are directed to preconcentrators having
a substrate that is capable of reversably bonding to various
chemical species, and in certain embodiments, the substrate may be
capable of releasing bound chemical species when heated or placed
in a magnetic field. In some embodiments, the substrate may a
resistivity of about 10.sup.3 ohm-meters (.OMEGA.m) to about
10.sup.-9 .OMEGA.m, about 10.sup.5 ohm-meters (.OMEGA.m) to about
10.sup.-7 .OMEGA.m, about 10.sup.4 ohm-meters (.OMEGA.m) to about
10.sup.-6 .OMEGA.m, about 10.sup.3 ohm-meters (.OMEGA.m) to about
10.sup.-5 .OMEGA.m, or any range or individual value encompassed by
these example ranges. In some embodiments, the substrate may have a
magnetic permeability (.mu.) of greater than about
1.times.10.sup.-4 H/m or, in certain embodiments, about
1.times.10.sup.-5 H/m to about about 10 H/m, about
1.times.10.sup.-4 H/m to about 1 H/m, about 1.times.10.sup.-3 H/m
to about 0.1 H/m, or any range or individual value encompassed by
these example ranges. In some embodiments, the substrate may have a
relative permeability of greater than 100, or, in particular
embodiments, the relative permeability may be about 75 to about
500, about 100 to about 400, about 150 to about 250 or any range or
individual value encompassed by these example ranges. Of course, in
various embodiments, the substrate may have any combination of
resistivity, magnetic permeability, and relative permeability in
which each range is encompassed by one or more of the example
ranges described above. The substrate of such embodiments may be
composed of a variety of materials including, for example, metal
fiber, woven metal fibers, non-woven metal fibers, porous metal,
sheet metal, metal coated glass, metal coated plastic, metal coated
ceramic, carbonaceous material, graphite, charcoal, activated
carbon, activated carbon cloth, and combinations thereof. In some
embodiments, the substrate may be porous to enable the flow of air
through the preconcentrator.
[0026] Examples of substrates may include, but are not limited to,
steel wool, nickel foam, ZnFe.sub.2O.sub.4 nanorods, iron
nanoparticles/glass wool, Co-ferrite aerogel, magnetic stainless
steel wool and the like. The physical properties of these
substrates are described in Table 1.
TABLE-US-00001 TABLE 1 Pres- Specific Surface Heating sure
Substrate .mu. Heat Area Rates Drop material (H/m) (kg/kJ.sup.-1K)
(m.sup.2/g) (.degree. C./s) (PSI) Steel Wool 8.75E-4 0.49 0.0075 50
(#3) Steel Wool 8.75E-4 0.49 0.0759 76 0.38 (#0000) Nickel Foam
1.25E-4 0.54 0.0026 60 0.08 ZnFe.sub.2O.sub.4 4.01E-4 -- 13.6 --
Nanorods COTS Ferrite 5.03E-5 1.05 0.000949 45.4 0.79 rod (NiZn)
Iron ~1 0.67 0.7 17.5 Nanoparticles/ Glass Wool Co-Ferrite 3.27E-4
-- 350 -- 1.39 aerogel* 434 Magnetic 8.75E-4 0.49 0.0075 52 0.37
Stainless Steel wool (#3)
In Table 1, magnetic permeability (.mu.) defines the response of
material to magnetic field, specific heat defines the material's
ability to be heated, surface area describes the exposed surface
area of the material that is capable of binding to a chemical
species, where a higher surface area means higher density of
surface binding sites, heating rate describes the rate at which the
substrate can be heated, and pressure drop describes the maximize
air flow required to increase sample volume. In particular
embodiments, the substrate may be steel wool.
[0027] In some embodiments, the preconcentrator may include a
coating on the substrate described herein. The coating in such
embodiments may be any coating that improves either bonding of
chemical species to the substrate, release of the bound chemical
species, or combinations thereof In certain embodiments, the
coating may be an organic coating. In some embodiments, the coating
may generally increase the affinity of the substrate for various
chemical species. In other embodiments, the coating may be
chemically selective allowing the coated substrate to have an
increased affinity for a specific target species or a particular
class or group of target species. For example, in some embodiments,
the coating may provide higher affinity for target chemical
species, while reducing the substrates affinity for common
background chemicals, such as water vapor, cigarette smoke, exhaust
fumes, gasoline fumes, dust, pollen, and the like or combinations
thereof. In certain embodiments, the coating may increase the
affinity of the substrate for chemical species including, but not
limited to, explosives, chemical warfare agents, and toxic
industrial compounds.
[0028] In particular embodiments, the coating may provide
discrimination between water and polar analytes. Thus, the coating
may have an affinity for polar chemical species while repulsing
water and non-polar chemical species, such as water vapor,
cigarette smoke, exhaust fumes, gasoline fumes, dust, pollen, and
the like or combinations thereof. In some embodiments, this
discrimination can be achieved by combining polar and non-polar
functional groups into the coating, and in other embodiments,
different coating materials having polar or non-polar functionality
can be combined and coated onto the substrate. Including both polar
and non-polar functionality in the coating may allow the non-polar
portion to reject water and non-polar interferents, while the polar
portion adsorbs the polar chemical species. In this manner, the
spurious signals due to water and interferents can be eliminated,
while simultaneously enhancing the signals due to the polar
molecules. Embodiments, are not limited to particular polar or
non-polar functional groups. For example, in some embodiments, the
polar functional groups may include amide (--C(O)NH.sub.2),
C.sub.1-C.sub.10 alkyl amide, carboxylic acid (--COOH),
C.sub.1-C.sub.10 alkyl carboxylic acid, hydroxyl (--OH),
C.sub.1-C.sub.10 alkyl hydroxyl, C.sub.1-C.sub.10 alkyoxy, aldehyde
(--C(O)H), C.sub.1-C.sub.10 alkyl aldehyde, ketone
(--C(O)CH.sub.3), C.sub.1-C.sub.10 alkyl ketone, amine
(--NH.sub.2), C.sub.1-C.sub.10 alkyl amine, epoxide, carbonyl
group, and combinations thereof. In various embodiments, the
non-polar functional groups incorporated into the coatings
described above may be C.sub.1-C.sub.10 alkyl, C.sub.2-C.sub.10
alkene, C.sub.2-C.sub.10 alkyne, C.sub.6-C.sub.16 arene, halide
(Br, F, Cl), C.sub.1-C.sub.10 alkyl halide, cycloalkyl, and
combinations thereof.
[0029] In certain embodiments, the coatings may be a polymer having
aromatic, or aliphatic backbone, and in certain embodiments, the
backbone may contain benzene, toluene, xylene, cyclohexane,
dimethylcyclohexane, ethylcyclohexane, and combinations thereof. In
particular embodiments, the coating may be composed of
functionalized xylene. For example, the coating may be a copolymer
of 4-hydroxy[2.2]paracyclophane and
4-perfluoroalkyl-carbonly[2.2]paracyclophane, in which the --OH
groups on the surface allow for the attachment of polar molecules
while the Teflon-like fluorine chain acts as a hydrophobic barrier
to water stabilization on the surface.
[0030] The coatings of various embodiments are generally thinly
applied to the substrate. For example, in certain embodiments, the
coating may have a thickness of about 200 nm. In other embodiments,
the coating may have a thickness of about 100 nm to about 500 nm.
The coating may be provided on any surface of the substrate, and in
certain embodiments, the substrate may be substantially coated on
all surfaces. For example, the coating may cover from about 50% to
about 99% of the total surface area of the substrate, or in some
embodiments, the coating may cover about 75% to about 98%, about
80% to about 97%, about 85% to about 95% of the total surface area
of the substrate or any individual value or range encompassed by
these values.
[0031] The coating may be applied by any method that provides for a
conformal coating over the various features of the substrate. In an
embodiment, the coating may be applied by chemical vapor deposition
(CVD). Vapor-based coating enables coating a variety of substrate
architectures ranging from planar surfaces such as metal and
silicon to interwoven scaffolds such as steel wool. Monomers having
diverse functionalization, such as, for example, functionalized
monomers of highly adhesive p-xylene, may be applied by CVD, and a
resultant copolymerization leads to uniform multi-functional
surfaces, and also modulates surface properties such as
composition, hydrophobicity, and surface charge. This allows for
conformal coating of surfaces instead of the spin-coating or wet
deposition methods that are common in the field. Conformal coatings
are important to micro-machined sensors and pre-concentrators due
to gaps that may form in the coating due to surface tension in the
spin cast film. In some embodiments, the coating may be applied by
other techniques known in the art, such as layer-by-layer assembly,
one sided plasma enhanced chemical vapor deposition, and one-sided
photopolymerization.
##STR00001##
[0032] The preconcentrators described herein can be used in a
variety of systems for sensing chemical species. For example, in
some embodiments, the preconcentrators may be incorporated into
larger sensing systems. In some embodiments, the sensing systems
may include a separate sample collector and detector. FIG. 1 is a
flow chart describing example of a process by which a system
including separate sample collection followed by detection. In such
embodiments, sample collection S1 may be carried out by drawing air
into a preconcentrator such as the preconcentrator cartridge
described above, and various chemical species and other vapors may
become associated with the substrate in the preconcentrator. In
some embodiments, after sample collection, the preconcentrator
cartridge may be sealed. The preconcentrator cartridge can then be
transported S2 to a location that includes a detector. In some
embodiments, the preconcentrator cartridge may be taken to the
detector directly following sample collection. For example, the
preconcentrator may be part of a sample collector and the sample
collector may be part of a transportable and movable system that
can be carried in a backpack or shoulder carrier, rolled on castors
or a mobile cart, or otherwise transported with the user, so that
sample collection and transport to the detector can occur
simultaneously. In other embodiments, the detector may be
maintained at a fixed position and the user may transport
preconcentrator to the detector or have the detector transported to
the preconcentrator. The preconcentrator may then be heated S3 to
release the chemical species and other vapors that were associated
with the substrate during sample collection and the chemical
species and vapors may be released into the detector. In some
embodiments, heating and release into the detector may occur in the
detector. For example, the detector may be equipped with an
induction heater designed to surround the preconcentrator and means
for directing air flow through the preconcentrator and into the
detector. In such embodiments, chemical species and vapors may be
released from the preconcentrator substrate and simultaneously
directed into the detector. In other embodiments, the heating unit
may be separate from the detector. The detector may be utilized to
detect the chemical species S4 released into the detector.
[0033] The preconcentrator includes all of the components and
physical properties described above. In some embodiments, the
preconcentrator may include a hollow cartridge that encapsulates
the substrate and may be constructed from various materials such
as, for example glass, quartz, Teflon, plastic, aluminum, and the
like and combinations thereof. The preconcentrator may include a
high surface-area substrate. As shown in the detail of FIG. 4, in
some embodiments, the coated substrate may include a porous
substrate material 26 with a conformal, stable, chemically
selective surface treatment, or coating 28, configured to have an
affinity for the target substrate or substrates. In other
embodiments, the substrate may be uncoated.
[0034] The preconcentrator cartridge in FIG. 2 may include an inlet
18 and outlet 19 that may be reversible sealable openings. The
reversible sealable openings on the preconcentrator may be created
by any means. For example, in certain embodiments, the reversible
seal may be removable caps, stoppers, corks, plastic films, or
combinations thereof. In other embodiments, the reversible seals
may be integral to the cartridge. For example, the openings may be
sealed using hinged covers or slide covers that can be moved to
allow access to the internal hollow body of the cartridge during
use and then resealed after the sample has been obtained. In still
other embodiments, the openings may be sealed using both integral
hinged or slide covers and removable caps, plastic films, or
stoppers. The stoppers may be constructed of rubber or plastic. To
remove the contents of the preconcentrator, the stopper may be
pinched with a hypodermic needle.
[0035] Various embodiments include a sample collection system
including a sample collector 31 as illustrated in FIG. 3. In some
embodiments, the preconcentrator may be reversibly attached to the
sample collector, such that a preconcentrator can be inserted into
the sample collector, a sample may be collected, and the
preconcentrator may be removed from the sample collector and
inserted into a detector device. In other embodiments, the
preconcentrator may be integrated into the sample collector as part
of a larger detector system, and in certain embodiments, this
system can be transportable and movable or can be carried in a
backpack or shoulder pack.
[0036] In various embodiments, the sample collector 31 may include
a housing 34. In some embodiments, the housing may include an
integrated preconcentrator holder sized to receive the
preconcentrator and hold the perconcentrator during sample
collecting. The holder may be equipped with one or more reversible
fasteners. For example, the preconcentrator or the cartridge may
include grooves that reversible interlock with grooves in the
preconcentrator holder by twisting or screwing the preconcentrator
into the holder. In other embodiments, the preconcentrator or the
cartridge may include one or more ridges that interconnect with
ridges in the preconcentrator holder allowing the preconcentrator
to snap into the preconcentrator holder. In some embodiments, the
preconcentrator holder 33 may be attached to the housing body 34 by
means of a flexible tubing or a hose allowing the user to move the
preconcentrator into small spaces. The preconcentrator holder 33 in
such embodiments may be attached to the distal end of the tubing or
has and may reversibly hold the preconcentrator 14 during the
operation of the preconcentrator using one or more reversible
fasteners such as those described above. The preconcentrator holder
may further include mechanism for opening the reversibly sealable
ends of the preconcentrator or the cartridge such that when the
preconcentrator is in place, the opening inside the preconcentrator
holder is opened allowing free flow of air from the preconcentrator
into the sample collector. In other embodiments, the user may
remove the reversibly sealable end of the preconcentrator or the
cartridge before introducing the preconcentrator into the
preconcentrator holder.
[0037] Air may be drawn through the preconcentrator by an air
suction pump 36 that is operably connected to the preconcetrator
holder 33. The air suction pump 36 may be any type of air pump
known in the art including, for example, a diaphragm pump, rotary
vane pump, a piston pump, or a fan the produces air current through
the preconcentrator holder and preconcentrator. In particular
embodiments, the air suction pump may be a regenerative air pump.
The flow of the air through the preconcentrator allows the analytes
and chemical compounds to be trapped inside the preconcentrator by
binding to the coated substrate, and the air flow produced by the
air suction pump 36 can vary among embodiments. For example, in
some embodiments, the air flow may produce through the
preconcentrator may be 1 m.sup.3/min to 10 m.sup.3/min or any
individual value or range encompassed by this range.
[0038] In some embodiments, the sample collector may also include a
pulsed air nozzle 32 connected to the sample collector housing body
34 that expels air from the sample collector and is positioned to
blow air into a sample collection area disturbing particles that
may have settled on surfaces in the sample collection area. The
pulsed air nozzle may be integral to the sample collection having
an outlet that is on a surface of the sample collector, and in some
embodiments, the outlet may include moveable blades or a nozzle
that directs the flow of air away from the sample collector. In
other embodiments, the pulsed air nozzle may include a flexible
hose or tubing that allows the flow of air to be directed by the
user. In some embodiments, the pulsed air nozzle including a
flexible hose or tubing may be mounted on a tripod. An air
compressor 35 for producing expelled air can be operably connected
to the pulsed air nozzle 32. In some embodiments, a number of
pulsed air nozzles and preconcentrator holders may be connected to
the same air suction pump and air compressor allowing for multiple
simultaneous sample collections.
[0039] In particular embodiments, the housing body may include
control devices and components 37 to control the working of the air
suction pump and the air compressor. In particular embodiments, the
sample collector, the air suction pump, and air compressor can be
mounted on a compact wheeled cart.
[0040] After sample collection, the preconcentrator may be removed
from the sample collector, and then the preconcentrator 14 may be
reversibly connected to a detector through an access port on the
detector device. The detector may include a rapid chemical
desorber, that may be configured as a heat source 30. In an
embodiment as represented by FIG. 4, the desorber may be configured
as a non-contact miniature induction heater 30. In an embodiment,
the indication heater may be battery powered for portability of the
detection system. Alternatively, for a detection system that may be
mounted or placed in a more permanent location, a plug-in power
source may be provided, and may include a plug for an alternating
current outlet, as well as additional appropriate power conversion
components to vary the voltage, amperage, and type of current,
etc.
[0041] In order to increase the concentration of target chemical
compounds in the vapor sample analyzed by a trace detection system,
the collected chemical vapor may be released from the substrate in
a very short burst to thereby enter the detection device as a more
highly concentrated sample. This may be accomplished by a
controlled rapid heating of the preconcentrator 14. In an
embodiment, the heating may be non-contact inductive heating that
raises the temperature of the substrate substantially uniformly to
a temperature of about 150.degree. C. to about 250.degree. C. in
less than about 5 seconds.
[0042] In some embodiments, the detector 12 in FIG. 2 may include a
heating element 30 that facilitates release of the bound analytes
from the substrate 24. In some embodiments, a compressor may be
further attached to the detector that generates a differential
pressure across the preconcentrator 14. The differential pressure
across the preconcentrator provides flow of vapors released from
the preconcentrator substrate 24 and is injected into a chemical
analyzer 15. Operation of the heating element 30 may be
synchronized with time, when differential pressure across the
preconcentrator changes, and air with vapors injected into chemical
analyzer. The device has means to control the volume of air with
released vapors injected into chemical analyzer. Such control is
provided by control of time, when differential pressure across the
preconcentrator is not equal to zero.
[0043] As represented in FIG. 5, an induction heater may include an
induction coil 40 (also generally represented as 30 in FIG. 4)
having a plurality of turns of an electrically conductive material
42, such as, for example a copper wire, that form a tunnel-like
structure. While the solenoid-type coil 40 that is shown in FIG. 5
is one illustrative embodiment having about eight individual coil
turns, it should be understood that the solenoid-type coil can
include any desired number of individual coil turns to form a
solenoid-type coil having a desired specified length. The solenoid
type coil 40 has opposite open ends 43 and 44, and a hollow portion
45 of a substantially uniform diameter that extends along the
entire length of the coil and is adapted to receive the component
to be heated, which as shown in FIG. 4, may be a sample collection
cartridge 24. The induction heating coil 40 may be provided with
terminals 50, 51 to connect the solenoid-type coils to a high
frequency power source 55 via power leads 56, 57.
[0044] The use of such an induction coil 40 may allow for a rapid
and accurate method of uniformly heating the contents of the
preconcentrator to a desired and predetermined temperature. As
shown in FIG. 4, a method of heating may include providing an
induction heating device that includes an elongated solenoid-type
induction heating coil 30 in close proximity around the
preconcentrator 14. The term "close proximity" is intended to refer
to the positioning of the outer surface of the preconcentrator 14
in relation to the induction coil 30. Preferably, the distance
between the outer surface of the preconcentrator 14 and the coil 30
should be such that the magnetic field generated by the coil does
not melt the preconcentrator, but that the portion of the
preconcentrator to be heated is within the magnetic field generated
by the coil to maximize the induction heating of that portion of
the preconcentrator. As such, an air gap may be present between the
outer surface of the portion of the preconcentrator 14 to be heated
and the induction coil. The air gap must be such that the induction
coil does not contact the preconcentrator. Without limitation, the
air gap between the preconcentrator and the induction coil may be
about 0.1 to about 0.5 inch.
[0045] The induction heating coil may then be provided or energized
with a source of high frequency power, such as a radio-frequency
power. The power supplied to the induction heating coil may be a
supply of alternating current power. The provision of the high
frequency alternating current to the induction coil produces an
electromagnetic field 60 (as shown in FIG. 5), within the
solenoid-type coil 30, 40. The electromagnetic field produces eddy
currents in the substrate material 26 and, thus, the coating 28 on
the substrate is heated. The high frequency current is provided to
the induction coil for a time sufficient to heat the coating
material to a desired and predetermined temperature to release any
bound analyte. The analyte may then be free to be carried by an
airflow 21 into the detector 12.
[0046] An induction heater generally may operates at either medium
frequency (MF) or radio frequency (R) ranges. The term "R
induction" is traditionally used to describe induction generators
designed to work in the frequency range from about 100 kHz up to
about 10 MHz, in practical terms however the frequency range tends
to cover about 100 to about 200 kHz. The output range typically
incorporates about 2.5 to about 40 kW. The term "MF induction" is
traditionally used to describe induction generators designed to
work in the frequency range from about 1 to about 10 kHz. The
output range typically incorporates about 50 to about 500 kW.
Induction heaters operating within the MF ranges are normally
utilized on medium to larger components and applications.
[0047] In an embodiment wherein the high surface-area substrate is
made out of magnetic stainless steel wool having a high magnetic
permeability, an inductive heating may be very efficient with
minimal power consumption. In such a scenario, the inductive
heating may require less than about 10 watts to heat about 0.1 gram
of substrate to the desired temp. With the possibility of such low
power requirements, the rapid desorber could be powered by
rechargeable batteries, and depending on the battery size and
configuration, may allow for over 300 current shots on a single
charge. The induction heater circuitry may also include built-in
over-current protection and feedback controls to limit peak
substrate temperature.
[0048] Some examples of components of the heater circuitry may
include: a basic LC tank circuit driven by MISFIT switches; an
on-board tunable frequency generator (100-400 kHz); an on-board
power supply (battery); an on-board temperature measurement for
temperatures up to about 350.degree. C.; an over-current protection
circuit; an over-voltage protection circuit; a temperature feedback
to limit temperature to about 250.degree. C.; a self-tuning
frequency feedback loop; an activation circuit to synch with
external trigger or manual switch 60 in FIG. 6; and on-board status
lights, that may include the following as non-limiting examples, a
low battery indicator 61, a power-on indicator 62, a fault
indicator 63 to indicates over-current or abnormal frequency, and a
"Heating" indicator 64. The protection circuits may provide
multiple protections against abnormal load conditions, and may
include, as non-limiting examples: robust output transistors; a
shutdown on fault conditions, such as input current over 4 amps or
a frequency that is too high; a "Pecking" with 2 second time-out on
continuous fault conditions so that, for example, a fault may be
left indefinitely without damage; protection against accidental
high coil voltages; and a circuit board such as a printed circuit
board (PCB) designed to accommodate high currents.
[0049] In an embodiment, a miniature induction heater for the
detection system may be powered by a small Lithium-Polymer Battery
(11.1V, 325 math), and the coil voltage may be adjustable from
about 20Vp-p (Volts peak to peak) to about 100Vp-p. The feedback
system may be configured to regulate coil voltage to accommodate
changes in coil and sample properties. The heating may be
controlled by manual switch or by logic input, and the coil and
sample cartridge may be easy to remove and replace when needed.
[0050] Induction heating of the pre-concentrating chamber allows
for high substrate heating rates, with low power consumption in a
low maintenance device. With induction heating fast desorption of
the analyte may be achieved as the RF-coil may induce a magnetic
field to cause the magnetic substrate to heat rapidly (greater than
about 80.degree. C./sec), with minimal power usage-low thermal mass
and high permeability may use less than about 10 Watts per shot of
RF power. An induction heater may also provide reduced maintenance
costs as the induction process requires no moving parts or heating
meshes/coils that typically require periodic replacement. In
addition, reduced usage costs may also be provided since the coated
substrates for use in the detection system may be provided as
easily replaceable cartridges. And, as a safety feature, the
maximum temperature may be controlled by choice of substrate
material, mounting geometry, and coating.
[0051] The sensing systems and devices described herein can have
multiple components, such as one or more preconcentrators, one or
more sample collectors, one or more heating elements, and one or
more detectors as a part of a single unit. In some embodiments, the
sensing systems may include a preconcentrator, a sample collector,
a heating element, and a detector as separate units, preferably on
movable carts. In other embodiments, the sensing systems may
include a preconcentrator and a sample collector as one unit, and a
heating element and a detector as part of one unit. In additional
embodiments, the sensing systems may include a preconcentrator, a
sample collector, and a heating element as part of one unit, and a
detector as a separate unit. In further embodiments, the sensing
systems described herein may include a preconcentrator, a heating
element, and a detector. The present invention is not to be limited
in scope by the specific embodiments described above. Many
modifications of the present invention, in addition to those
specifically recited above would be apparent to those skilled in
the art in light of the instant disclosure.
[0052] This disclosure is not limited to the particular systems,
devices and methods described, as these may vary. The terminology
used in the description is for the purpose of describing the
particular versions or embodiments only, and is not intended to
limit the scope.
[0053] In the above detailed description, reference is made to the
accompanying drawings, which form a part hereof. In the drawings,
similar symbols typically identify similar components, unless
context dictates otherwise. The illustrative embodiments described
in the detailed description, drawings, and claims are not meant to
be limiting. Other embodiments may be used, and other changes may
be made, without departing from the spirit or scope of the subject
matter presented herein. It will be readily understood that the
aspects of the present disclosure, as generally described herein,
and illustrated in the Figures, can be arranged, substituted,
combined, separated, and designed in a wide variety of different
configurations, all of which are explicitly contemplated
herein.
[0054] The present disclosure is not to be limited in terms of the
particular embodiments described in this application, which are
intended as illustrations of various aspects. Many modifications
and variations can be made without departing from its spirit and
scope, as will be apparent to those skilled in the art.
Functionally equivalent methods and apparatuses within the scope of
the disclosure, in addition to those enumerated herein, will be
apparent to those skilled in the art from the foregoing
descriptions. Such modifications and variations are intended to
fall within the scope of the appended claims. The present
disclosure is to be limited only by the terms of the appended
claims, along with the full scope of equivalents to which such
claims are entitled. It is to be understood that this disclosure is
not limited to particular methods, reagents, compounds,
compositions or biological systems, which can, of course, vary. It
is also to be understood that the terminology used herein is for
the purpose of describing particular embodiments only, and is not
intended to be limiting.
[0055] As used in this document, the singular forms "a," "an," and
"the" include plural references unless the context clearly dictates
otherwise. Unless defined otherwise, all technical and scientific
terms used herein have the same meanings as commonly understood by
one of ordinary skill in the art. Nothing in this disclosure is to
be construed as an admission that the embodiments described in this
disclosure are not entitled to antedate such disclosure by virtue
of prior invention. As used in this document, the term "comprising"
means "including, but not limited to."
[0056] While various compositions, methods, and devices are
described in terms of "comprising" various components or steps
(interpreted as meaning "including, but not limited to"), the
compositions, methods, and devices can also "consist essentially
of" or "consist of" the various components and steps, and such
terminology should be interpreted as defining essentially
closed-member groups.
[0057] With respect to the use of substantially any plural and/or
singular terms herein, those having skill in the art can translate
from the plural to the singular and/or from the singular to the
plural as is appropriate to the context and/or application. The
various singular/plural permutations may be expressly set forth
herein for sake of clarity.
[0058] It will be understood by those within the art that, in
general, terms used herein, and especially in the appended claims
(e.g., bodies of the appended claims) are generally intended as
"open" terms (e.g., the term "including" should be interpreted as
"including but not limited to," the term "having" should be
interpreted as "having at least," the term "includes" should be
interpreted as "includes but is not limited to," etc.). It will be
further understood by those within the art that if a specific
number of an introduced claim recitation is intended, such an
intent will be explicitly recited in the claim, and in the absence
of such recitation no such intent is present. For example, as an
aid to understanding, the following appended claims may contain
usage of the introductory phrases "at least one" and "one or more"
to introduce claim recitations. However, the use of such phrases
should not be construed to imply that the introduction of a claim
recitation by the indefinite articles "a" or "an" limits any
particular claim containing such introduced claim recitation to
embodiments containing only one such recitation, even when the same
claim includes the introductory phrases "one or more" or "at least
one" and indefinite articles such as "a" or "an" (e.g., "a" and/or
"an" should be interpreted to mean "at least one" or "one or
more"); the same holds true for the use of definite articles used
to introduce claim recitations. In addition, even if a specific
number of an introduced claim recitation is explicitly recited,
those skilled in the art will recognize that such recitation should
be interpreted to mean at least the recited number (e.g., the bare
recitation of "two recitations," without other modifiers, means at
least two recitations, or two or more recitations). Furthermore, in
those instances where a convention analogous to "at least one of A,
B, and C, etc." is used, in general such a construction is intended
in the sense one having skill in the art would understand the
convention (e.g., "a system having at least one of A, B, and C"
would include but not be limited to systems that have A alone, B
alone, C alone, A and B together, A and C together, B and C
together, and/or A, B, and C together, etc.). In those instances
where a convention analogous to "at least one of A, B, or C, etc."
is used, in general such a construction is intended in the sense
one having skill in the art would understand the convention (e.g.,
"a system having at least one of A, B, or C" would include but not
be limited to systems that have A alone, B alone, C alone, A and B
together, A and C together, B and C together, and/or A, B, and C
together, etc.). It will be further understood by those within the
art that virtually any disjunctive word and/or phrase presenting
two or more alternative terms, whether in the description, claims,
or drawings, should be understood to contemplate the possibilities
of including one of the terms, either of the terms, or both terms.
For example, the phrase "A or B" will be understood to include the
possibilities of "A" or "B" or "A and B."
[0059] In addition, where features or aspects of the disclosure are
described in terms of Markush groups, those skilled in the art will
recognize that the disclosure is also thereby described in terms of
any individual member or subgroup of members of the Markush
group.
[0060] As will be understood by one skilled in the art, for any and
all purposes, such as in terms of providing a written description,
all ranges disclosed herein also encompass any and all possible
subranges and combinations of subranges thereof. Any listed range
can be easily recognized as sufficiently describing and enabling
the same range being broken down into at least equal halves,
thirds, quarters, fifths, tenths, etc. As a non-limiting example,
each range discussed herein can be readily broken down into a lower
third, middle third and upper third, etc. As will also be
understood by one skilled in the art all language such as "up to,"
"at least," and the like include the number recited and refer to
ranges which can be subsequently broken down into subranges as
discussed above. Finally, as will be understood by one skilled in
the art, a range includes each individual member. Thus, for
example, a group having 1-3 cells refers to groups having 1, 2, or
3 cells. Similarly, a group having 1-5 cells refers to groups
having 1, 2, 3, 4, or 5 cells, and so forth.
[0061] Various of the above-disclosed and other features and
functions, or alternatives thereof, may be combined into many other
different systems or applications. Various presently unforeseen or
unanticipated alternatives, modifications, variations or
improvements therein may be subsequently made by those skilled in
the art, each of which is also intended to be encompassed by the
disclosed embodiments.
EXAMPLE
[0062] A novel miniature trace explosives trace preconcentrator
device was developed as shown in FIG. 6. The device had the
following characteristics as shown in Table 2
TABLE-US-00002 TABLE 2 Collected media Particles, aerosol and
vapors Type of substrate Proprietary functional monomer on
stainless steel wool Pulsed heating Inductive RF (patent pending)
Preconcentration factor Up to 1000 Low pressure drop 0.4 PSI for
0.1 g substrate Fast heating 85-125.degree. C./sec Released vapors
volume As little as 5-10 mL. Could be adjusted. Tuned affinity to a
group of chemicals Nitro-, Phosphorus-, etc. Low price for the
coated substrate <$0.15 Reusable Up to 20 times Low outgassing
Up to 275.degree. C. Excellent coating adhesion At least 20 cycles
Coating thermal stability AT least 250.degree. C. Not sensitive to
a thermal shock Tested at 150.degree. C./sec Low mass media 0.1 g
and 0.5 g Low power consumption <50 Joules for heating 0.1 g
substrate to 250.degree. C. COTS detectors tested with
pre-concentrator IMS, DMS and MS Selectivity improvement in
presence of 2.sup.nd hand smoke, gasoline exhaust Device Size 3.2''
.times. 1.7'' .times. 4.3'' Pre-concentrator tube ID 0.2'' Weight
with a battery 312 g (11 oz) Battery Lithium-Polymer Battery (11.1
V, 325 mAh) Number of heating cycles on a battery Up to 200
[0063] To measure quantitative preconcentration efficiency, the
preconcentrator was interfaced with a quadruple mass spectrometer
(MS). Experimental results (FIGS. 9 and 10) show repeatable TNT
vapor pre-concentration. It should be noted that preconcentration
efficiency will depend on the type of explosive and analyte vapor
pressure.
[0064] Preconcentrator performance also was tested with COTS trace
detector, QS-150, manufactured by Implant Sciences Corp. 0.5 g of
DNT was placed into 50 ml syringe. Syringe pump was used to control
sample air-flow and released vapors air-flow. Total time of vapor
sampling and analysis for each set of experiment was 15 sec. Each
curve on FIGS. 11-14 corresponds to 1 sec of sampling/analysis. All
spectra are shown only for 29-40 ms region. Reactive ion peak (RIP)
maximum amplitude was close to 3000 counts.
[0065] FIG. 11 shows IMS spectra of laboratory air. FIG. 12 shows
IMS spectra related to DNT vapors injected from a syringe into ETD.
The spectra were taken with interval of 1 sec. When preconcentrator
was placed between the syringe with DNT vapors and IMS detector
sampling port, DNT vapors could not reach the detector (see FIG.
13). After DNT vapor sampling the pre-concentrator with collected
DNT vapors was heated within 1.8 sec and released vapors were
injected into the detector. In a set of experiments we varied
air-flow of released DNT vapors. FIG. 14 shows IMS detector
response to released DNT vapors released with various flow rates of
50, 75, 100 and 120 ml/min.
* * * * *