U.S. patent application number 13/567362 was filed with the patent office on 2014-02-06 for photoluminescent oxygen probe tack.
The applicant listed for this patent is John Eastman, Daniel W. Mayer. Invention is credited to John Eastman, Daniel W. Mayer.
Application Number | 20140034847 13/567362 |
Document ID | / |
Family ID | 48782171 |
Filed Date | 2014-02-06 |
United States Patent
Application |
20140034847 |
Kind Code |
A1 |
Mayer; Daniel W. ; et
al. |
February 6, 2014 |
PHOTOLUMINESCENT OXYGEN PROBE TACK
Abstract
A photoluminescent oxygen probe comprising a tack with a layer
of a pressure-sensitive adhesive and an oxygen-sensitive
photoluminescent element on the underside of the head. The probe is
effective for sensing oxygen concentration within an enclosed space
by puncturing the container defining the enclosed space the with
the probe's shank and adhering the underside of the probe's head to
the container so as to sealingly surround the puncture, thereby
placing the oxygen-sensitive photoluminescent dye on the underside
of the probe's head into sensible communication with the enclosed
space through the puncture hole.
Inventors: |
Mayer; Daniel W.; (Wyoming,
MN) ; Eastman; John; (Rogers, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mayer; Daniel W.
Eastman; John |
Wyoming
Rogers |
MN
MN |
US
US |
|
|
Family ID: |
48782171 |
Appl. No.: |
13/567362 |
Filed: |
August 6, 2012 |
Current U.S.
Class: |
250/459.1 ;
250/458.1 |
Current CPC
Class: |
G01N 21/8507 20130101;
Y10T 436/20 20150115; G01N 21/77 20130101; Y10T 436/25875 20150115;
Y10T 436/209163 20150115; Y10T 436/207497 20150115; G01N 21/643
20130101 |
Class at
Publication: |
250/459.1 ;
250/458.1 |
International
Class: |
G01N 21/64 20060101
G01N021/64 |
Claims
1. A photoluminescent oxygen probe comprising: (a) a tack with a
head and a shank extending longitudinally from an underside of the
head, (b) a layer of a pressure-sensitive adhesive on the underside
of the head, and (c) an oxygen-sensitive photoluminescent element
on the underside of the head.
2. The probe of claim 1 wherein the layer of adhesive is positioned
intermediate the head of the tack and the oxygen-sensitive
photoluminescent element.
3. The probe of claim 1 wherein the oxygen-sensitive
photoluminescent element includes at least an oxygen-sensitive
photoluminescent dye embedded within an oxygen-permeable
hydrophobic polymer carrier.
4. The probe of claim 1 wherein the oxygen-sensitive
photoluminescent element includes at least a support structure
coated with an oxygen-sensitive photoluminescent dye embedded
within an oxygen-permeable hydrophobic polymer carrier.
5. The probe of claim 4 wherein the oxygen-sensitive
photoluminescent dye is a tetrabenzoporphyrin.
6. The probe of claim 1 wherein the layer of pressure-sensitive
adhesive is less than 2 mm thick.
7. The probe of claim 1 wherein the layer of pressure-sensitive
adhesive is less than 1.5 mm thick.
8. The probe of claim 6 wherein (i) the shank defines a
longitudinal axis, (ii) the layer of pressure sensitive adhesive
has a peripheral edge, (iii) the oxygen-sensitive photoluminescent
element has a peripheral edge, and (iv) the adhesive layer extends
radially from the longitudinal axis of the shank at least 2 mm
beyond the peripheral edge of the oxygen-sensitive photoluminescent
element around the entire periphery of the oxygen-sensitive
photoluminescent element.
9. The probe of claim 1 wherein (i) the shank defines a
longitudinal axis, (ii) the layer of pressure sensitive adhesive
has a peripheral edge, (iii) the oxygen-sensitive photoluminescent
element has a peripheral edge, and (iv) the adhesive layer extends
radially from the longitudinal axis of the shank at least 4 mm
beyond the peripheral edge of the oxygen-sensitive photoluminescent
element around the entire periphery of the oxygen-sensitive
photoluminescent element.
10. A method for measuring the oxygen concentration within a space
enclosed by a structure, comprising the steps of: (a) obtaining a
photoluminescent oxygen probe according to claim 1, (b) puncturing
the structure with the probe's shank, (c) adhering the underside of
the probe's head to an exterior surface of the container so as to
sealingly surround the puncture, thereby placing the
oxygen-sensitive photoluminescent dye on the underside of the
probe's head into sensible communication with the enclosed space
through the puncture, (d) allowing the oxygen concentration in
sensible communication with the layer of oxygen-sensitive
photoluminescent dye to equilibrate with the oxygen concentration
within the enclosed space, and (e) ascertaining an oxygen
concentration within the enclosed space by: (i) exposing the
oxygen-sensitive photoluminescent dye on the underside of the
probe's head to excitation radiation through the probe's head, (ii)
measuring radiation emitted by the excited oxygen-sensitive
photoluminescent dye, and (iii) converting the measured emission to
an oxygen concentration based upon a known conversion
algorithm.
11. A method for measuring the oxygen concentration within a space
enclose by a structure, comprising the steps of: (a) obtaining a
photoluminescent oxygen probe according to claim 8, (b) puncturing
the structure with the probe's shank, (c) adhering the underside of
the probe's head to an exterior surface of the container so as to
sealingly surround the puncture, thereby placing the
oxygen-sensitive photoluminescent dye on the underside of the
probe's head into sensible communication with the enclosed space
through the puncture, (d) allowing the oxygen concentration in
sensible communication with the layer of oxygen-sensitive
photoluminescent dye to equilibrate with the oxygen concentration
within the enclosed space, and (e) ascertaining an oxygen
concentration within the enclosed space by: (i) exposing the
oxygen-sensitive photoluminescent dye on the underside of the
probe's head to excitation radiation through the probe's head, (ii)
measuring radiation emitted by the excited oxygen-sensitive
photoluminescent dye, and (iii) converting the measured emission to
an oxygen concentration based upon a known conversion
algorithm.
12. The method of claim 8 wherein the space is a retention chamber
of a hermetically sealed package containing an oxygen labile
pharmaceutical or foodstuff.
13. A method for monitoring changes in oxygen concentration within
a space enclosed by a membrane, comprising the steps of: (a)
obtaining a photoluminescent oxygen probe according to claim 1, (b)
puncturing the structure with the probe's shank, (c) adhering the
underside of the probe's head to an exterior surface of the
container so as to sealingly surround the puncture, thereby placing
the oxygen-sensitive photoluminescent dye on the underside of the
probe's head into sensible communication with the enclosed space
through the puncture, (d) allowing the oxygen concentration in
sensible communication with the layer of oxygen-sensitive
photoluminescent dye to equilibrate with the oxygen concentration
within the enclosed space, (e) ascertaining an oxygen concentration
within the enclosed space over time by: (i) repeatedly exposing the
equilibrated oxygen-sensitive photoluminescent dye on the underside
of the probe's head to excitation radiation through the probe's
head over time, (ii) measuring radiation emitted by the excited
equilibrated oxygen-sensitive photoluminescent dye after at least
some of the exposures, (iii) measuring passage of time during the
repeated excitation exposures and emission measurements, and (iv)
converting at least some of the measured emissions to an oxygen
concentration based upon a known conversion algorithm, and (f)
reporting at least one of (i) at least two ascertained oxygen
concentrations and the time interval between those reported
concentrations, and (ii) a rate of change in oxygen concentration
within the enclosed space calculated from data obtained in step
(d).
14. A method for monitoring changes in oxygen concentration within
a space enclosed by a membrane, comprising the steps of: (a)
obtaining a photoluminescent oxygen probe according to claim 8, (b)
puncturing the structure with the probe's shank, (c) adhering the
underside of the probe's head to an exterior surface of the
container so as to sealingly surround the puncture, thereby placing
the oxygen-sensitive photoluminescent dye on the underside of the
probe's head into sensible communication with the enclosed space
through the puncture, (d) allowing the oxygen concentration in
sensible communication with the layer of oxygen-sensitive
photoluminescent dye to equilibrate with the oxygen concentration
within the enclosed space, (e) ascertaining an oxygen concentration
within the enclosed space over time by: (i) repeatedly exposing the
equilibrated oxygen-sensitive photoluminescent dye on the underside
of the probe's head to excitation radiation through the probe's
head over time, (ii) measuring radiation emitted by the excited
equilibrated oxygen-sensitive photoluminescent dye after at least
some of the exposures, (iii) measuring passage of time during the
repeated excitation exposures and emission measurements, and (iv)
converting at least some of the measured emissions to an oxygen
concentration based upon a known conversion algorithm, and (f)
reporting at least one of (i) at least two ascertained oxygen
concentrations and the time interval between those reported
concentrations, and (ii) a rate of change in oxygen concentration
within the enclosed space calculated from data obtained in step
(d).
15. The method of claim 13 wherein the space is a retention chamber
of a hermetically sealed package containing an oxygen labile
pharmaceutical or foodstuff.
Description
BACKGROUND
[0001] Solid-state polymeric materials based on oxygen-sensitive
photoluminescent dyes are widely used as optical oxygen probes.
See, for example United States Published Patent Applications
2009/0029402, 2008/8242870, 2008/215254, 2008/199360, 2008/190172,
2008/148817, 2008/146460, 2008/117418, 2008/0051646, 2006/0002822
and U.S. Pat. Nos. 7,569,395, 7,534,615, 7,368,153, 7,138,270,
6,689,438, 5,718,842, 4,810,655, and 4,476,870. Such optical probes
are available from a number of suppliers, including Presens
Precision Sensing, GmbH of Regensburg, Germany, Oxysense of Dallas,
Tex., United States, and Luxcel Biosciences, Ltd of Cork,
Ireland.
[0002] Such probes may be interrogated through many common
packaging materials and therefore allow nondestructive measurement
of the oxygen concentration within an enclosure by simply
incorporating a probe within the packaging, typically adhered to
the inside surface of the cover. Unfortunately, there are certain
applications where incorporation of such a probe into the packaging
is not acceptable--such as packages made from materials that
interfere with interrogation of the probe (e.g., opaque and
metalized films), packages in which the presence of such a probe
inside the packaging may be mistakenly perceived by consumers as an
undesired contamination of the packaged product, or packages whose
per package value or profit margin cannot accommodate the cost of
incorporating a probe into every package or tracking those
containing a probe when only select packages include a probe.
[0003] Hence, a need exists for an inexpensive disposable probe
that can be systematically employed in accordance with a quality
control program to quickly and accurately inspect the oxygen
concentration within indiscriminately selected packages.
SUMMARY OF THE INVENTION
[0004] A first aspect of the invention is a photoluminescent oxygen
probe comprising (a) a tack with a head and a shank extending
longitudinally from an underside of the head, (b) a layer of a
pressure-sensitive adhesive on the underside of the head, and (c)
an oxygen-sensitive photoluminescent element on the underside of
the head. The oxygen-sensitive photoluminescent element is
preferably comprised of a photoluminescent dye embedded within an
oxygen-permeable hydrophobic polymer carrier.
[0005] A second aspect of the invention is a method for measuring
oxygen concentration within a space enclosed by a structure
employing an oxygen-sensitive probe according to the first aspect
of the invention. The method includes the steps of (A) obtaining a
photoluminescent oxygen probe according to the first aspect of the
invention, (B) puncturing the structure with the probe's shank, (C)
adhering the underside of the probe's head to an exterior surface
of the container so as to sealingly surround the puncture, thereby
placing the oxygen-sensitive photoluminescent dye on the underside
of the probe's head into sensible communication with the enclosed
space through the puncture, (D) allowing the oxygen concentration
in sensible communication with the layer of oxygen-sensitive
photoluminescent dye to equilibrate with the oxygen concentration
within the enclosed space, and (E) ascertaining an oxygen
concentration within the enclosed space by: (i) exposing the
oxygen-sensitive photoluminescent dye on the underside of the
probe's head to excitation radiation through the probe's head, (ii)
measuring radiation emitted by the excited oxygen-sensitive
photoluminescent dye, and (iii) converting the measured emission to
an oxygen concentration based upon a known conversion
algorithm.
[0006] A third aspect of the invention is a method for monitoring
changes in oxygen concentration within an enclosed space employing
an oxygen-sensitive probe according to the first aspect of the
invention. The method includes the steps of (A) obtaining a
photoluminescent oxygen probe according to the first aspect of the
invention, (B) puncturing the structure with the probe's shank, (C)
adhering the underside of the probe's head to an exterior surface
of the container so as to sealingly surround the puncture, thereby
placing the oxygen-sensitive photoluminescent dye on the underside
of the probe's head into sensible communication with the enclosed
space through the puncture, (D) allowing the oxygen concentration
in sensible communication with the layer of oxygen-sensitive
photoluminescent dye to equilibrate with the oxygen concentration
within the enclosed space, (E) ascertaining an oxygen concentration
within the enclosed space over time by: (i) repeatedly exposing the
equilibrated oxygen-sensitive photoluminescent dye on the underside
of the probe's head to excitation radiation through the probe's
head over time, (ii) measuring radiation emitted by the excited
equilibrated oxygen-sensitive photoluminescent dye after at least
some of the exposures, (iii) measuring passage of time during the
repeated excitation exposures and emission measurements, and (iv)
converting at least some of the measured emissions to an oxygen
concentration based upon a known conversion algorithm, and (F)
reporting at least one of (i) at least two ascertained oxygen
concentrations and the time interval between those reported
concentrations, and (ii) a rate of change in oxygen concentration
within the enclosed space calculated from data obtained in step
(E).
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is an exploded perspective view of one embodiment of
the invention.
[0008] FIG. 2 is a top view of the invention depicted in FIG.
1.
[0009] FIG. 3 is a side view of the invention depicted in FIG.
1.
[0010] FIG. 4 is a partial cross-sectional side view of the
invention depicted in FIG. 1 taken along line 4-4 with the
thickness of each layer grossly enlarged to facilitate viewing of
the individual layers.
[0011] FIG. 5 is a microscopically enlarged view of a portion of
the oxygen-sensitive photoluminescent element depicted in FIG. 4 to
facilitate viewing of the individual discrete strands of the
element.
[0012] FIG. 6 is a further microscopically enlarged cross-sectional
view of one of the strands of the oxygen-sensitive photoluminescent
element depicted in FIG. 5 to facilitate viewing of the individual
discrete components of the element.
[0013] FIG. 7 is a side view of the invention depicted in FIG. 1
applied to a package.
[0014] FIG. 8 is a cross-sectional side view of a central portion
of the invention depicted in FIG. 6 with the thickness of each
layer grossly enlarged to facilitate viewing of the individual
layers.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Definitions
[0015] As used herein, including the claims, the term "foodstuff"
means any substance suitable for being eaten or drunk by animals,
including humans, for nutrition or pleasure, or used as an
ingredient in such a substance.
[0016] As used herein, including the claims, the phrase "oxygen
impermeable" means a material that has an oxygen transmission rate
of less than 0.1 cm.sup.3/m.sup.2 day when measured in accordance
with ASTM D 3985.
Nomenclature
[0017] 10 Oxygen Probe
[0018] 20 Tack
[0019] 21 Head of Tack
[0020] 21a Topside of Head
[0021] 21b Underside of Head
[0022] 22 Shank of Tack
[0023] 22b Distal End of Shank
[0024] 30 Oxygen-Sensitive Photoluminescent Element
[0025] 31 Support Structure
[0026] 32 Polymer Carrier
[0027] 33 Oxygen-Sensitive Photoluminescent Dye
[0028] 34 Coated Individual Strand of Support Structure
[0029] 39 Peripheral Edge of Oxygen-Sensitive Photoluminescent
Element
[0030] 40 Pressure Sensitive Adhesive Layer
[0031] 49 Peripheral Edge of Pressure Sensitive Adhesive Layer
[0032] 50 Peripheral Margin
[0033] 60 Release Liner
[0034] 61 Tab on Release Liner
[0035] 70 Label
[0036] F Foodstuff
[0037] P Hermetically Sealed Packaging
[0038] S Retention Chamber or Space
Description
[0039] Construction and Theory of Operation
[0040] Referring generally to FIG. 7, the invention is an
oxygen-sensitive probe or sensor 10 useful for optically measuring
oxygen concentration within an enclosed space S, such as the
retention chamber S of a hermetically sealed package P containing a
foodstuff F. Referring generally to FIGS. 1, 2 and 3, the probe 10
includes a tack 20, oxygen-sensitive photoluminescent element 30
and layer of a pressure-sensitive adhesive 40.
[0041] The tack 20 has a head 21 and a shank 22. The head 21 should
be transparent or translucent to radiation at the excitation and
emission wavelengths of the photoluminescent element 30. Suitable
materials include specifically, but not exclusively, glass and
various polymers such as poly(methyl methacrylate) and clear vinyl.
The shank 22 extends longitudinally from the underside 21b of the
head 21. The distal end 22b of the shank 22 forms a sharp suitable
for piercing typical packaging materials such as mylar films,
polyethylene and polypropylene containers, polyvinyl chloride
bottles, etc.
[0042] For typical applications, the head 21 preferably has a
diameter of about 6 to 20 mm, most preferably about 10 to 15 mm,
and the shank 22 preferably has a longitudinal length of about 6 to
20 mm, most preferably about 10 to 15 mm. A head 21 with a diameter
smaller than about 6 mm is difficult to manufacture and awkward to
use, while a diameter greater than about 20 mm increases the
expense of the tack 20 without a concomitant improvement in
handling or performance. A shank 22 with a length smaller than
about 6 mm hinders the ability of the tack 20 to effectively
penetrate and pierce through packages or containers P, while a
length greater than about 20 mm increases the expense of the tack
20 without a concomitant improvement in handling or
performance.
[0043] Referring to FIG. 4, both the oxygen-sensitive
photoluminescent element 30 and the layer of pressure-sensitive
adhesive 40 are positioned on the underside 21b of the head 21 of
the tack 20.
[0044] Referring to FIGS. 5 and 6, the oxygen-sensitive
photoluminescent element 30 includes an oxygen-sensitive
photoluminescent dye 33, preferably embedded within an
oxygen-permeable polymer carrier 32, and coated onto a support
structure 31.
[0045] The oxygen-sensitive photoluminescent dye 33 may be selected
from any of the well-known oxygen sensitive photoluminescent dyes
33. One of routine skill in the art is capable of selecting a
suitable dye 33 based upon the intended use of the probe 10. A
nonexhaustive list of suitable oxygen sensitive photoluminescent
dyes 33 includes specifically, but not exclusively,
ruthenium(II)-bipyridyl and ruthenium(II)-diphenylphenanothroline
complexes, porphyrin-ketones such as
platinum(II)-octaethylporphine-ketone, platinum(II)-porphyrin such
as platinum(II)-tetrakis(pentafluorophenyl)porphine,
palladium(II)-porphyrin such as
palladium(II)-tetrakis(pentafluorophenyl)porphine, phosphorescent
metallocomplexes of tetrabenzoporphyrins, chlorins, azaporphyrins,
and long-decay luminescent complexes of iridium(III) or
osmium(II).
[0046] Typically and preferably, the oxygen-sensitive
photoluminescent dye 33 is compounded with a suitable
oxygen-permeable and hydrophobic polymeric carrier 32. Again, one
of routine skill in the art is capable of selecting a suitable
carrier 32 based upon the intended use of the probe 10 and the
selected dye 33. A nonexhaustive list of suitable polymers for use
as the oxygen-permeable hydrophobic carrier 32 includes
specifically, but not exclusively, polystryrene, polycarbonate,
polysulfone, polyvinyl chloride and some co-polymers.
[0047] The support structure 31 should be constructed from a
material capable of providing sufficient structural integrity to
the oxygen-sensitive photoluminescent element 30. The material
should also be transparent or translucent to radiation at the
excitation and emission wavelengths of the dye 33 in the
photoluminescent element 30. Suitable materials include
specifically, but not exclusively, glass, spunbond glass fibers and
polymeric films such as PET, Nylon, PVDC (Saran), etc.
[0048] Referring generally to FIGS. 1 and 4, the probe 10 includes
a layer of a pressure sensitive adhesive 40 on underside 21b of the
head 21 of the tack 20--the same side as the photoluminescent
element 30--for adhering the probe 10 to the surface (unnumbered)
of a container or package P defining an enclosed space or retention
chamber S whose oxygen concentration is to be measured. The
adhesive 40 may but preferably does not cover the photoluminescent
element 30.
[0049] Referring to FIGS. 7 and 8, the probe 10 can be placed into
sensing communication with the retention chamber S of a container
or package P by pushing the shank 22 of the tack 20 through the lid
or sidewall of the container or package P and pressing the adhesive
layer 40 on the underside 21b of the head 21 of the tack 20 into
sealing engagement with the container or package P. Once the probe
10 is adhered to the container or package P, oxygen is exchanged
between the photoluminescent element 30 and the content of the
retention chamber S of the container or package P through the
opening (unnumbered) in the container or package P created by the
shank 22 of the tack 20. Unless the probe 10 is read for several
days after being applied to a container or package P, diffusion of
oxygen across the head 21 of the tack 20 is statistically
insignificant. In those situations where diffusion of oxygen across
the head 21 of the tack 20 may become an issue, diffusion can be
minimized by constructing the tack 20 from an oxygen impermeable
material (i.e., an extremely low oxygen transmission rate (OTR)) or
applying a coating of an oxygen impermeable material to the head 21
of the tack 20. Unfortunately, this same option is not available
for minimizing diffusion across the layer of pressure-sensitive
adhesive 40 as pressure-sensitive adhesives have a fairly high OTR.
Hence, in order to minimize diffusion from the sides of the probe
10, the thickness of the pressure-sensitive adhesive layer 40
should be limited (e.g., about 1 to 2 mm) so as to minimize the
surface area exposed to the surrounding environment, and a sizable
margin 50 provided from the edge(s) 49 of the adhesive layer 40 to
the edge(s) 39 of the photoluminescent element 30 (e.g., about 1 to
10 mm) to maximize the width of the adhesive between the
surrounding environment and the photoluminescent element 30. The
desired effect can generally be achieved with a peripheral margin
50 of between about 1 to 10 mm, most preferably about 2 to 5 mm. A
peripheral margin 50 less than about 1 mm does not provide a
sufficient delay nor reduction in radial oxygen diffusion through
the adhesive layer 40 and into sensing contact with the
photoluminescent element 30, while a peripheral margin 50 of
greater than about 10 mm increases the expense of the tack 20
without a concomitant improvement in performance.
[0050] A release liner 60 is preferably employed over the exposed
surface of the adhesive layer 40 to prevent contamination and
premature adhesion of probe 10 during storage and handling. A
radially extending tab 61 can be provided on the release liner 60
to facilitate removal.
[0051] A label 70 can be adhered to the topside 21a of the head 21
of the tack 20 for provided relevant information about the probe 10
such as source, type, phone number for ordering additional probes
10 or obtaining technical support, website address where purchasing
and performance details can be obtained, etc. When employed, either
(1) The label 70 needs to be transparent or translucent to
radiation at the excitation and emission wavelengths of the
photoluminescent element 30, or (2) that portion of the label 70
which would overlay the photoluminescent element 30 needs to be
removed (e.g., an annular label).
[0052] Manufacture
[0053] The probe 10 can be conveniently manufactured by (1)
obtaining a suitable tack 20, (2) spindling a photoluminescent
element 30 (with or without a prepunched hole) onto the underside
21b of the head 21 of the tack 20, (3) applying a layer of
pressure-sensitive adhesive 40 onto the underside 21b of the head
21 of the tack 20 before or after the photoluminescent element 30
is spindled onto the tack 20 using conventional coating techniques,
(4) spindling a release liner 60 (with or without a prepunched
hole) over the exposed surface (unnumbered) of the adhesive layer
40, and (5) optionally applying a label 70 to the topside 21a of
the head 21 of the tack 20.
[0054] The photoluminescent element 30 can be manufactured by the
traditional methods employed for manufacturing such elements 30.
Briefly, the element 30 can be conveniently manufactured by (A)
preparing a coating cocktail (not shown) which contains the
photoluminescent oxygen-sensitive dye 33 and an oxygen-permeable
carrier polymer 32 in an organic solvent (not shown) such as
ethylacetate, (B) applying the cocktail to the support structure
31, and (C) allowing the cocktail (not shown) to dry, whereby a
solid-state thin film oxygen-sensitive photoluminescent element 30
is formed on the support structure 31.
[0055] Generally, the concentration of the carrier polymer 32 in
the organic solvent (not shown) should be in the range of 0.1 to
20% w/w, with the ratio of dye 33 to polymer 32 in the range of
1:20 to 1:10,000 w/w, preferably 1:50 to 1:5,000 w/w.
[0056] Use
[0057] The probe 10 can be used to quickly, easily, accurately and
reliably measure oxygen concentration within an enclosed space S.
Briefly, the probe 10 is used to measure oxygen concentration
within an enclosed space S by (A) pushing the shank 22 of the tack
20 through the lid or sidewall of a container or package P defining
the enclosed space S until the adhesive layer 40 on the underside
21b of the head 21 of the tack 20 sealingly engages the container
or package P, thereby placing the photoluminescent element 30 in
sensible communication with the enclosed space S through the
opening (unnumbered) in the container or package P created by the
shank 22 of the tack 20, (B) allowing the concentration of oxygen
in sensible communication with the oxygen-sensitive
photoluminescent element 30 to equilibrate with the oxygen
concentration in the enclosed space S, and (C) ascertaining oxygen
concentration within the enclosed space S by (i) exposing the
oxygen-sensitive photoluminescent element 30 to excitation
radiation through the head 21 of the tack 20, (ii) measuring
radiation emitted by the excited oxygen-sensitive photoluminescent
element 30 through the head 21 of the tack 20, and (iii) converting
the measured emission to an oxygen concentration based upon a known
conversion algorithm. Such conversion algorithms are well know to
and readily developable by those with routine skill in the art.
[0058] In a similar fashion, the probe 10 can be used to quickly,
easily, accurately and reliably monitor changes in oxygen
concentration within an enclosed space S. Briefly, the probe 10 is
used to monitor changes in oxygen concentration within an enclosed
space S by (A) pushing the shank 22 of the tack 20 through the lid
or sidewall of a container or package P defining the enclosed space
S until the adhesive layer 40 on the underside 21b of the head 21
of the tack 20 sealingly engages the container or package P,
thereby placing the photoluminescent element 30 in sensible
communication with the enclosed space S through the opening
(unnumbered) in the container or package P created by the shank 22
of the tack 20, (B) allowing the concentration of oxygen in
sensible communication with the oxygen-sensitive photoluminescent
element 30 to equilibrate with the oxygen concentration in the
enclosed space S, (C) ascertaining oxygen concentration within the
enclosed space S by (i) repeatedly exposing the oxygen-sensitive
photoluminescent element 30 to excitation radiation through the
head 21 of the tack 20 over time, (ii) measuring radiation emitted
by the excited oxygen-sensitive photoluminescent element 30 through
the head 21 of the tack 20 after at least some of the exposures,
(iii) measuring passage of time during the repeated excitation
exposures and emission measurements, and (iv) converting at least
some of the measured emission to an oxygen concentration based upon
a known conversion algorithm, and (D) reporting at least one of (i)
at least two ascertained oxygen concentrations and the time
interval between those reported concentrations, or (ii) a rate of
change in oxygen concentration within the enclosed space S
calculated from data obtained in step (C). Again, conversion
algorithms used to convert the measured emissions to an oxygen
concentration are well know to and readily developable by those
with routine skill in the art.
[0059] The radiation emitted by the excited probe 10 can be
measured in terms of intensity and/or lifetime (rate of decay,
phase shift or anisotropy), with measurement of lifetime generally
preferred as a more accurate and reliable measurement technique
when seeking to establish oxygen concentration via measurement of
the extent to which the dye 33 in the photoluminescent element 30
has been quenched by oxygen.
* * * * *