U.S. patent application number 12/939265 was filed with the patent office on 2011-03-03 for method and apparatus for detection of bioaerosols.
Invention is credited to Adam K. Arabian, Micah A. Carlson, Protagoras N. Cutchis, Harvey W. Ko, David R. Kohler, Michael P. McLoughlin, George M. Murray, Jennifer A. Nix, Jennifer L. Sample, Cheryl S. Schein.
Application Number | 20110049390 12/939265 |
Document ID | / |
Family ID | 29250956 |
Filed Date | 2011-03-03 |
United States Patent
Application |
20110049390 |
Kind Code |
A1 |
Murray; George M. ; et
al. |
March 3, 2011 |
Method and Apparatus for Detection of Bioaerosols
Abstract
A method and apparatus for evaluating a bioaerosol sample is
provided which includes detecting frequency and/or time resolution
factors that allow discriminate between a plurality of signals
emitted by the bioaerosol to selectively detect biological
materials contained in the bioaerosol sample from materials of
non-biological origin and potentially associated with a pathogenic
bioaerosol.
Inventors: |
Murray; George M.;
(Columbia, MD) ; Schein; Cheryl S.; (Rockville,
MD) ; Kohler; David R.; (Ocean Pines, MD) ;
Sample; Jennifer L.; (Bethesda, MD) ; Nix; Jennifer
A.; (Ellicott City, MD) ; Cutchis; Protagoras N.;
(Highland, MD) ; Arabian; Adam K.; (Louisville,
KY) ; Ko; Harvey W.; (Ellicott City, MD) ;
Carlson; Micah A.; (Baltimore, MD) ; McLoughlin;
Michael P.; (Sykesville, MD) |
Family ID: |
29250956 |
Appl. No.: |
12/939265 |
Filed: |
November 4, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12141298 |
Jun 18, 2008 |
7830515 |
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12939265 |
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10503168 |
Jul 30, 2004 |
7494769 |
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PCT/US03/11723 |
Apr 16, 2003 |
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12141298 |
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60373080 |
Apr 16, 2002 |
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Current U.S.
Class: |
250/459.1 ;
250/458.1 |
Current CPC
Class: |
G01N 21/645 20130101;
G01N 21/6408 20130101; G01N 2021/6421 20130101; G01N 21/6486
20130101; G01N 21/64 20130101; G01N 2021/6413 20130101 |
Class at
Publication: |
250/459.1 ;
250/458.1 |
International
Class: |
G01N 21/64 20060101
G01N021/64; G01J 1/58 20060101 G01J001/58 |
Claims
1. A method for detecting bio-materials contained in a bioaerosol
sample comprising exciting the bioaerosol sample emitting at least
one initial emission signal and a subsequent time-delayed emission
signal that allows for time resolution to be used as a
discriminator between the at least one and subsequent emission
signals to selectively detect the bio-materials from materials of
non-biological origin.
2. The method of claim 1, wherein the aerosol sample emits an
additional emission signal simultaneously with emitting the at
least one initial emission signal, the at least one initial signal
having a wavelength differing from wavelengths of the additional
and time-delayed emission signal.
3. The method of claim 2, wherein the at least one initial and
additional emission signals are fluorescent, whereas the subsequent
time-delayed signal is a phosphorescent signal.
4. The method of claim 1, further comprising comparing the at least
one initial and the subsequent time-delayed signals with respective
threshold values to maximize sensitivity of the detection of the
biomaterials of interest.
5. The method of claim 1, further comprising collecting the
bioaerosol sample on a liquid surface or on a solid surface.
6. The method of claim 5, further comprising adding a heavy atom
perturber and an oxygen scavenger to the collected bioaerosol
sample to emit the subsequent time delayed emission signal at room
temperatures.
7. The method of claim 1, wherein the at least one initial and
time-delayed emission signals each are detected by first and second
optical channels controllably operative to detect intensities of
each of the detected emission signals.
8. A system for alerting building occupants of the presence of a
potentially pathogenic bioaerosol comprising a plurality of sensors
each located in a strategically selected place and operating in: a
fluorescence detection based mode, wherein at least two fluorescent
signals having different wavelengths associated with biomaterials
of interest are detected; and a phosphorescence detection based
mode, wherein a fluorescent signal and a time-delayed
phosphorescent signals are detected, the phosphorescent signal
allowing for time resolution to be used as a discriminator between
the at least one and the time-delayed signal to selectively detect
biomaterials of interest from materials of non-biological origin;
and a central processing unit operative to identify a respective
sensor sensing the pathogenic aerosol.
9. The system of claim 8, wherein the central processing unit is
operative to trigger an auxiliary detection system operative to
confirm and identify the biomaterials of interest in response to a
signal generated by the respective sensor and indicating the
presence of the pathogenic aerosol.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 12/141,298, filed Jun. 18, 2008, issued Nov.
9, 2010 as U.S. Pat. No. 7,830,515, which is a divisional
application of U.S. patent application Ser. No. 10/503,168, filed
Jul. 30, 2004, issued Feb. 24, 2009, as U.S. Pat. No. 7,494,769,
which is a 371 of PCT/US03/11723, which claims the benefit of U.S.
Provisional Application Ser. No. 60/373,080, filed on Apr. 16,
2002, the contents of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to a sampling
methodology. More particularly, the present invention is directed
to a method and apparatus utilizing a luminescence spectroscopy to
detect bioaerosols and alert of the presence of a potentially
pathogenic bioaerosol.
[0004] 2. Description of the Related Art
[0005] Aerosols of biological origin, whether formed intentionally
or unintentionally, represent a potential threat of infection by
pathogens. This threat is particularly daunting in the context of
closed spaces, such as buildings. A variety of methods directed to
identifying harmful biological materials are known. One of the
known methods is based on the principles of the luminescence
spectroscopy and is concerned with the production, measurement, and
interpretation of electromagnetic spectra arising from either
emission or absorption of radiant energy by various substances.
[0006] One aspect of the luminescence spectroscopy provides for the
ability of biological materials to fluoresce due to the presence of
proteins that possess certain amino acids. Fluorescence occurs when
fluorophores and fluorescent particles absorb light at a given
wavelength and then immediately emit light at a longer wavelength.
Although not all particles fluoresce, some bio-aerosols contain
intrinsic fluorophores that could potentially be used to tag the
sample as a bioaerosol. Common fluorophores found in bioaerosol
are, for example, Nicotinamide Adenine Dinucleotide (NADH),
Tryptophan, Tyrosine, and Riboflavin. Each of these fluorophores is
characterized by respective peak excitation and corresponding
emission wavelengths.
[0007] The primary fluorescent amino acids are tyrosine and
tryptophan. The latter compound absorbs and emits at longer
wavelengths and is less likely to have spectral overlaps with
compounds that are not of a biological origin. However, there are
still many environmental elements and hydrocarbons that will also
fluoresce in the same wavelength as tryptophan, let alone the rest
of the above-mentioned fluorophores.
[0008] Another aspect of the luminescence spectroscopy that may
provide a tool for detecting biological materials is
phosphorescence. As compared to fluorescence, phosphorescence is
characterized by the time delay emission signal that allows for
time-resolution to be used as a discriminator between samples that
fluoresce versus those that phosphoresce. Hence, it is possible to
delay the detection of the signal until after the light source has
been extinguished and the fluorescent signal has disappeared. In
addition to the time delay, Tryptophan phosphoresces at a longer
emission wavelength.
[0009] Most of the known biological detectors incorporate
fluorescence as a means for detecting the presence of a biological
aerosol. Although fluorescence is a relatively simple approach, its
major disadvantage, as discussed above, is the low selectivity for
the bioaerosols of interest.
[0010] Current biological aerosol detection/triggering technology
including the Biological Aerosol Warning Sensor (BAWS) developed by
the Massachusetts Institute of Technology and the ultra Violet
Aerodynamic Particle Sizer (UVAPS) developed by TSI is acceptable.
However, these instruments are expensive, power hungry, large, and
require complex algorithms to determine relatively little
information.
[0011] A need, therefore, exists for a methodology either
perfecting or complementing a fluorescence detection technique and
for an inexpensive, low power, robust apparatus carrying out the
inventive methodology.
[0012] Thus, one of the objects of the present invention is to
provide a method for detecting pathogenic bioaerosols having a
secondary detection technique to complement fluorescence.
[0013] Another object of the present invention is to provide an
apparatus for carrying out the inventive method and capable of
effectively collecting bioaerosols and selectively detecting the
presence of the biological materials of interest contained in the
bioaerosols.
[0014] Still another object of the present invention is to provide
the inventive apparatus adapted to generate a warning upon
detecting the biological materials of interest and to trigger
secondary, more sophisticated, equipment for the confirmation of
the initially detected materials and their further
identification.
[0015] A further object of the present invention is to provide the
inventive apparatus characterized by a simple, space- and
cost-efficient structure.
[0016] Yet another object of the invention is to provide a
detection system including multiple inventive apparatuses and
deployed in a single location to provide added discrimination of
actual threat levels.
SUMMARY OF THE INVENTION
[0017] These and other objects have been achieved by a new method,
characterized by the collection of bioaerosols and further
excitation of a sample thereof to controllably discriminate between
biomaterials that fluoresce versus those that phosphoresce. The
latter would indicate the probability of the presence of biological
materials of interest in the excited sample.
[0018] The inventive method utilizes both fluorescence vs.
fluorescence-based detection as well as fluorescence vs.
phosphorescence-based detection. The optical system of the
inventive sensor includes two optical channels both operative to
detect fluorescence signals emitted at different wavelengths and
associated with different bioagents. However, in addition to
exclusively detecting fluorescence, one of the optical channels is
also configured to detect phosphorescence after the detection of
the fluorescence has been completed.
[0019] In the case of fluorescence vs. phosphorescence, if the
former is detected by one of the optical channels, the possibility
of the presence of a biomaterial of interest exists. Subsequent
detection of the phosphorescence during the second stage indicates
the probability of the presence of the biomaterial of interest.
Since the inherent advantage of phosphorescence over fluorescence
is the time delayed emission signal, the inventive apparatus is
operative to allow for time-resolution to be used as a
discriminator between samples that fluoresce versus those that
phosphoresce. As a result, the two-stage inventive method maximizes
the probability of detection and minimizes the number of false
alarms.
[0020] In accordance with another aspect of the inventive method, a
heavy atom perturber that has chemical affinity for association
with the molecules, whose phosphorescence is desired, is bonded
with the sampled material. As a consequence, if a biological agent
to be detected is present in the sampled material, phosphorescence
occurs at a known wavelength.
[0021] A further aspect of the present invention provides for an
apparatus operative to carry out the inventive method. The
inventive apparatus includes mechanical, optical, and electronic
sub-systems controllably cooperating with one another to collect a
sample of bioaerosol, optically excite it and electronically
process emitted signals to detect the presence of the biomaterials
of interest.
[0022] One of the advantages of the inventive apparatus is based on
the characteristic of the phosphorescence to emit light waves at
wavelengths after a light source has been extinguished. By
configuring a two-channel optical system and providing an
electronic processing unit with software, which executes on the
processing unit, the desired sequence of mechanical, optical and
electronic operations leading to the minimization of false alarms
and the maximization of detection is established and maintained.
This, of course, does not eliminate the possibility of
simultaneously detecting different fluorescence intensities by both
optical channels, only one of which is configured to detect
phosphorescence in addition to the ability to detect
fluorescence.
[0023] In accordance with a further aspect of the present
invention, phosphorescence of the biomaterials of interest at room
temperature is induced by controllably adding a heavy atom
perturber to the sample in the presence of an oxygen scavenger. The
latter is used to minimize the possibility of the fluorescence of
non-biological materials. As a result, the apparatus can indicate
the presence of the biomaterial of interest based on its
phosphorescence without, however eliminating the detection of this
material based on its fluorescence.
[0024] While the inventive apparatus can be used for a variety of
purposes, desirably it can be associated with a plurality of
identical apparatuses or sensors to provide a network operative to
alert building, office and/or industrial site occupants of the
presence of a potentially pathogenic bioaerosol. Simplicity of the
inventive structure and its space-efficient configuration can be
used to construct a warning system capable of generating a real
time detection/information about bioagents of interest and of
triggering a more sophisticated system to confirm and identify
these bioagents.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The above and other objects, features and advantages will
become more readily apparent from the following detailed
description accompanied by the drawings, in which:
[0026] FIG. 1 is a flow chart illustrating an inventive method for
detecting bioaerosols;
[0027] FIG. 2 is a perspective simplified view of an apparatus
carrying out the inventive method of FIG. 2;
[0028] FIG. 3 is a schematic diagram of the fluidics and
electro-optics systems of the inventive apparatus shown in FIG.
2;
[0029] FIG. 4 is a simplified perspective view of the optic system
shown in FIG. 3;
[0030] FIG. 5 is a flow chart illustrating the operation of the
processor of the electronic system diagrammatically illustrated in
FIG. 4; and
[0031] FIG. 6 is a schematic diagram of a warning system
installable in a building.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] FIG. 1 illustrates an inventive method 10 based on the
realization that hazardous biological materials dispersed in a
particulate-containing airstream emit phosphoresce radiation at
room temperature if bonded with an external heavy atom perturber
(EHAP) in the presence of an oxygen scavenger, e.g., sodium
sulfite.
[0033] In accordance with the above-stated inventive concept, the
method 10 provides for the collection of a bioaerosol sample, as
indicate by step 12. Following the collection of the bioaerosol
sample, the latter is mixed with an EHAP. Among EHAPs for use
herein, include, for example, one or more of potassium iodide,
lead, thallium, lutetium, gallium, cesium, and barium each of which
advantageously have a sufficient chemical affinity for association
with the molecule of fluorophores contained in an airstream. Common
fluorophores found in aerosols that can potentially be used to tag
the collected aerosol sample are, for example, NADH, Tryptophan,
Tyrosine, Riboflavin and the like. For example, if Tryptophan is
complexed with an EHAP, as indicated by step 14 of FIG. 1, it will
phosphoresce when excited at a predetermined excitation wavelength,
as shown by step 16. To provide distinct phosphorescence, it is
desirable to reduce the fluorescent radiation generated by the
materials of interest at a shorter wavelength by mixing the sample
of bioaerosol with an EHAP in the presence of the oxygen scavenger.
Ox
[0034] However, the fluorescence radiation can be indicative of
biological materials of interest and neglecting a fluorescent
signal may lead to catastrophic results. As a consequence, the
inventive method 10 provides for the detection of fluorescence, as
an initial detection technique, as shown by step 18 of FIG. 1.
Moreover, the inventive method can be utilized to provide for
simultaneous detection of two or more fluorescence signals having
different intensities, each of which may be associated with a
respective bioagent contained in the collected bioaerosol.
[0035] Criticality of phosphorescence versus fluorescence in the
context of the method 10 is the time delayed emission signal
associated with the former and allowing for time-resolution to be
used as a discriminator between the detected biomaterials that
fluoresce against those that phosphoresce. The time delay is an
advantage because it is possible to delay the detection of the
signal until after the light source has been extinguished, as will
be explained in detail below. Another critical characteristic
associated with phosphorescence when compared with fluorescence is
the different wavelengths of the emitted signals. For example, when
excited with 285 nm light, Tryptophan will fluoresce at 360 nm, but
it will phosphoresce at 450 nm. The above-identified differences
are important to the inventive method providing for extinguishing
an excitation source during step 20 to finally determine the
probability of the presence of biological agents or biomaterials of
interest if a phosphorescent signal is detected during step 22.
Accordingly, the inventive method advantageously employs a
two-stage fluorescence/phosphorescence detection technique allowing
for a sequential identification of bio-materials of interest. Also,
the inventive method allows for detection of two fluorescent
signals associated with different wavelengths and intensities,
which can be indicative of different fluorophores.
[0036] Turning now to FIGS. 2-5, a sensor 30 is able to detect
bioaerosols based on a dual channel luminescence detection
technique in accordance with the inventive method. The sensor 30 is
a compact device having dimensions, which are approximately
12''.times.16''.times.8''. In addition, as will become clear from
the following description, the sensor 30 has a simple and cost
efficient structure allowing, thus, the sensor to be placed in
large quantities in a building to alert building occupants of
potentially dangerous biomaterials contained in air.
[0037] As shown in FIG. 2, the sensor 30 comprises three primary
units including at least a mechanical system, an optical system and
an electronic system. The mechanical system is configured to
collect a sample and transport the latter to the optical system
operative to excite, emit and detect emission signals having
wavelengths of interest. The electronic system is adapted to
process the emissions signals and control the desired sequence of
operations established to carry out the inventive method 10. These
systems of the sensor 30 are packaged in a housing 24 made from a
material capable of withstanding mechanical loads to preserve the
functionality of the entire system even under adverse
conditions.
[0038] The mechanical system includes at least a particle sampler
or collector/concentrator as generally indicated as 34 (FIG. 2) and
operative to rapidly provide the sample in a form that can be
processed by the optical system. There are several issues that make
sampling for biological agents particularly challenging. The first
issue is that the sampling is normally targeted at living
organisms; therefore, the technology must not "harm" the sample.
Secondly, the target bio-material is generally only one component
of a complex matrix of biological elements and chemical compounds
that may affect the detection process, so the sample must often be
purified to some extent. Lastly, the sample must be highly
concentrated for a rapid analysis. An air-liquid surface virtual
and/or real concentrator and/or an air-solid surface concentrator
can readily deal with all of the above-discussed issues within the
scope of the invention. As the names indicate, the former provides
for the impingement of airborne particulates upon a reservoir
filled with liquid, whereas the latter features a solid surface
such as a bare or coated with mineral oil/vacuum grease tape,
paper, metal or any other suitable solid surface. Both types of the
impactors are utilized within the scope of the present invention,
as will become more readily apparent from the following
description. In practical terms, a sampling stage is initiated upon
actuation of a vacuum pump directing an airstream 36 (FIG. 3)
through the concentrator into a sample vessel or collector 38 (FIG.
3), which is located downstream from the impactor. Depending on the
particular test, a sample collector 38 can be configured to have a
fluid reservoir or a solid surface both serving as a particle
impinging and collecting concentrator.
[0039] If the collector 38 features a liquid surface, the
mechanical system is provided with a sample of a fluid reservoir 44
(FIGS. 2 and 3), which is in fluid communication with the
collector. Particularly, a fluidic control scheme includes a
controllable first pinch valve 31 opening in response to a signal
generated by the electronic system and simultaneously with
actuation of a peristaltic pump 32. As a result, buffered water
from the reservoir 44 is first pumped into the collector 38, which,
in this case, is an impinger type of aerosol to liquid collector.
After the aerosol has been collected, the liquid sample is
delivered through another controllable pinch valve 31 to an optical
cell 50, which can be associated with either a flow through cuvette
or a closed cuvette (FIG. 3).
[0040] In accordance with one aspect of the inventive concept
provided for detection of fluorescence and phosphorescence, as the
sample is transported towards the cell 50, it is mixed with
chemicals, i.e., the heavy atom perturber and oxygen scavenger.
Particularly, the sample is bonded with the EHAP stored in a
chemical reservoir 46 (FIG. 2) and controllably delivered into a
sample path upon actuation of another peristaltic pump 32. Note
that various types of pumps and valves are contemplated with the
scope of invention and subject only to local objectives and
experimentation.
[0041] Alternatively, if the collector 38 is configured as an
aerosol to solid surface concentrator, a mechanical means, which
among others can include a simple robotic arm (not shown), delivers
the concentrated sample to the cell 50. While transporting the
sample, it is mixed with the EHAP and the oxygen scavenger to
induce phosphorescence light associated with any biomaterial of
interest, provided, of course, that the material is present in the
sample.
[0042] Having delivered the sample mixed with the EHAP to the
optical cell 50, the optical system, illustrated generally as 26 in
FIG. 2, provides an optical analysis of the delivered sample by
causing the sample to induce fluorescence and phosphorescence light
signals and convert them into electrical signals. The optical
system is configured to excite the sample by initially turning a
light source, such as a Xenon flash lamp 52 (FIGS. 3 and 4), which
generates discontinuous pulses of light incident upon the sample.
As a result, if the biomaterial of interest is present, the sample
emits fluorescent and possibly phosphorescent lights propagating
along two optical channels, each of which includes a photo
multiplier tubes (PMT) 56, 58 (FIGS. 3 and 4) amplifying signals
emitted at selective frequencies.
[0043] To analyze the specimens constituting the sample, the
current level applied to the lamp 52 causes the latter to emit
optical energy in the ultraviolet range. To reduce the amount of
dispersion, the output from lamp 52 is processed by a filter 54, so
that the sample is only excited by a predetermined wavelength
varying within the UV range; the filtered output is eventually
focused on the cell 50 by means of an upstream lens assembly 60. To
boost the signal amplitude at the integrator output, the lamp 52
preferably generates three pulses fired in rapid succession at
about 25 ms intervals.
[0044] Assuming that the sample contains the bio-materials of
interest capable of emitting at least fluorescent light, two
optical channels of the optical system are configured to
selectively pass and amplify fluorescent signals propagating at
different frequencies. Based on experimentation data, the 450 nm
PMT 58 optically coupled with an outlet of the first optical
sub-system, which includes a filter 62 and focusing lens systems
60, generates an amplified electrical signal in response to
detection fluorescence of NADH. The other optical channel includes
the 360 nm PMT 56 coupled to a second optical sub-system, which is
configured similarly to the first one, and used to primarily detect
fluorescence. In addition, the 450 nm PMT is also capable of
detecting phosphorescence of Tryptophan upon extinguishing the lamp
52 for a predetermined period of time.
[0045] It has to be noticed that all distances, including that
between the optical cell 50 and the PMTs 56, 58, the optical cell
and the lamp 52, have to be experimentally optimized to allow for
maximum light transmission through the system. A few optional
modifications of the overall optical system can include, for
example, a gated PMT 59 (FIG. 3) that can be added to the 450PMT in
order to control the time delay activation of the photo multiplier
tube and to prevent the saturation of the phosphorescence
measurement by the fluorescent signal. Another potential
contribution to the saturation issue is the proper selection of the
filter 62 coupled to the 450PMT; it is desirable that a filter
rated at optical density (OD) 5 with about a 10 nm bandwidth be
installed. The relatively high OD provides more efficient blocking
of light emissions that are not within the bandwidth of interest.
Note that all dimensions, ranges and numeric characteristics are
subject to numerous variations, which primarily depend from the
type of bio-agents to be detected.
[0046] Assuming that either two fluorescence signals have been
simultaneously emitted or the fluorescence and phosphorescence
light signals have been sequentially emitted, the output electrical
signals of the PMTs 56, 58 are received by the electronic system 70
(FIGS. 3 and 5). The electronic system is configured to process
electrical signals outputted by the PMTs 56, 58 via connectors 64
(FIG. 3) into amplifier circuits of a controller card 28 (FIG. 2)
and to compare the processed signals with respective reference
values. The desired sequence of actuation of pumps, valves and
other components as well as automatic triggering of the more
sophisticated equipment are likewise controlled by the electronic
system 70.
[0047] The heart of the electronic system 70 is a processor having
software executed thereon for sequentially operating the sensor 30
in a manner consistent with the inventive method 10. As is typical
for the rest of the disclosed components, among a variety of
suitable devices, a MC68HC11, which is an 8-bit processor chip, and
three amplifier circuits control system timing and overall signal
processing.
[0048] As better illustrated in FIG. 5, software executed on the
processor initially actuates the mechanical system. A particular
sequence of pump and valve operations depends on whether the
collector 38 has an air-liquid or air-solid surface configuration.
If the air-liquid surface type is incorporated in the sensor 30,
initially the peristaltic pump 32 and the first pinch valve 31 are
actuated in a rate- and time controlled manner to allow for the
passage of liquid into the sample vessel, as indicated by a step
90. Subsequently, the vacuum pump responsible for drawing the
aerosol 36 (FIG. 3) into the sample vessel is turned on to sample
and collect biomaterials of interest, as indicated by a step 92.
Further transportation of the concentrated sample to the optical
system, is associated with the controlled actuation of the
downstream pump 32 and the second valve 31 openable to provide
mixing of the sample with the EHAP and the oxygen scavenger, as
indicated by step 94. The latter is necessary if the sensor 30 is
used to detect not only fluorescence, but phosphorescence as
well.
[0049] Alternatively, if the concentrator 38 has a solid surface,
the aerosol is initially forced along an impactor means at 72 to
accumulate on the solid surface where the sample is mixed with the
EHAP and O.sub.2 scavenger injected, as shown by step 94, either
directly onto the surface. Alternatively, the EHAP and O.sub.2
scavenger can be added as the concentrated sample is transported,
as shown by step 74, towards the photocell 50.
[0050] Upon delivery of the sample to the optical cell 50, the lamp
52 is energized in a controlled pulsed manner, as shown at 76, and
if the biomaterials of interest are present in the sample, they
produce a signal detected and magnified by the PMT 56. A comparator
of the electronic system 70 compares the received signal with a
first threshold, as shown by step 78, and if the intensity of this
signal is lower than the first threshold, the mechanical system is
re-activated to evacuate the sample to a sample waste reservoir 80.
Note, if the sensor 30 operates only in a fluorescence vs.
fluorescence mode, both PMTs 56 and 58 detect respective
fluorescent signals simultaneously. Both signals propagating at
different wavelength and having different intensity are compared
with respective reference or threshold values. For example, the
optical channel provided with the PMT 56 is operative to detect
fluorescence emissions in the 360 nm-wavelength band which is
associated with tryptophan and bioaerosols containing this
fluorophore. The other channel including the PMT 58 is operative to
detect fluorescence emissions in the 450 nm-wavelength band
associated with NADH and bioaerosols containing the latter.
[0051] If, however, the sensor 30 in a fluorescence vs.
phosphorescence mode, the signal detected after the lamp 52 has
been extinguished at 82 by the PMT 58 corresponds to a
phosphorescent signal. This signal can be associated with
Tryptophan phosphorescence. Similarly to the first mode of
operation, in the second mode of operation, both
signals--fluorescence and phosphorescence--are sequentially
compared to respective thresholds. If the phosphorescence signal
passes the master, as indicated by step 84, the sample is conveyed
to a sample reservoir 86 where it is stored for further
examination. However, even if the phosphorescence master is not
passed in the second mode, the sample is still saved in the sample
reservoir 86 for further detection, since it certainly contains a
material, which can be of a biological origin capable of
fluorescing, as determined at 78. The latter procedure is also
applicable to the first mode operation, wherein as either of the
two fluorescence signals at least matches a respective threshold,
the sample is rerouted to the sample reservoir 86 for further
detection.
[0052] Software executed on the processor, can trigger the more
sophisticated detection system, as shown by step 88, which, in
turn, is coupled to the sample reservoir 86 to further evaluate the
stored sample. Furthermore, an audible signal generated by a
piezoelectric or other type buzzer 98 and a visual signal 100 can
be generated either immediately upon detecting the biomaterial of
interest.
[0053] As shown in FIG. 6, it is contemplated to assemble a
plurality of the sensors 30 and strategically placed them in a
building or in any other "closed" space structure equipped with a
central processor 102. The central processor will be able to
receive a signal generated by any of the sensors 30 and identify
the location of the triggered sensor. The central processor 102 can
trigger the more sophisticated detection equipment 96 configured to
continue the examination of the stored sample and characterized by
higher sensitivity and selectivity capabilities.
[0054] Further modification of the sensor 30 may include, for
example, the installation of a control panel coupled to the
electronic system 70 and operative to allow the operator to
manipulate variable parameters including, but not limited to the
timing of the pumps for the fluidic system, the reference (alarm)
threshold values, the collection time, the duration of on-state of
the lamp and many others. There is an opportunity to improve the
selectivity of the sensor 30 by including phosphorescence
measurements or adding a particle counter. It should be understood
that the inventive sensor can operate on a cyclical basis.
[0055] While the invention has been shown and described with
references to certain preferred embodiments thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and scope of the invention as defined by the appended claims.
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