Pathogen and particle detector system and method

• US 20070013910A1
• Filed: 07/29/2005
• Published: 01/18/2007
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: Azbil Corporation (Azbil BioVigilant Incorporated)
• Original Assignee: BioVigilant Systems Incorporated (Azbil BioVigilant Incorporated)
• Inventors: Morrell, Michael, Jiang, Jian-Ping, Babico, John
• Granted Patent: US 7,430,046 B2
• Time in Patent Office: Days
• US Class Current: 356/336
• CPC Class Codes: G01N 15/0205 by optical means
• CPC Class Codes: G01N 2015/0088 Biological contaminants; Fouling
• CPC Class Codes: G01N 2015/019 Biological contaminants; Fouling
• CPC Class Codes: G01N 21/05 Flow-through cuvettes G01N21/09 takes precedence; handling fluid samples G01N1/10
• CPC Class Codes: G01N 21/53 within a flowing fluid, e.g. smoke
• CPC Class Codes: G01N 21/6486 Measuring fluorescence of biological material, e.g. DNA, RNA, cells G01N21/6428 takes precedence
• CPC Class Codes: H03K 5/04 by increasing duration; by decreasing duration

Abstract

A particle detector has a sample area of cross section no in excess of about 2 mm for containing environmental fluid, a light source on one side of the sample area for directing a collimated or nearly collimated beam of light through the sample air or water so that part of the light beam will be scattered by any particles present in the air or water while the remainder remains unscattered, and a beam diverting device on the opposite side of the sample area for diverting or blocking at least the unscattered portion of the beam of light and directing at least part of the scattered light onto a detector. The detector produces output pulses in which each pulse has a height proportional to particle size and a pulse height discriminator obtains the size distribution of airborne particles detected in the air or water sample at a given time from the detector output. The detector may also include a device for discriminating between biological agents and inorganic particles.

Claims

1. An airborne particle detector system, comprising:

an outer housing having an air sample cell area of cross-section not in excess of about 2 mm;

a light source on one side of the air sample cell area for sending a focused beam of light through the sample air, whereby portions of the beam of light are scattered at various angles by particles of various sizes present in the sample area, and an unscattered portion of the beam of light remains unscattered;

a beam blocking device on the opposite side of the air sample cell area for blocking at least the portion of the unscattered portion of the beam of light;

a first detector with control circuitry positioned in the light path after the beam blocking device for detecting a portion of the scattered light, and producing an output including information on the number of particles in the light path within a predetermined size range.

2. The system claims in claim 1, further comprising one or more of the following features:

(a) an alarm unit for providing a warning signal if the number of particles within a predetermined size range exceeds a predetermined normal level within that size range, and

preferably wherein the alarm unit produces an alarm signal if the number of particles detected within a size range of approximately 1 to 7 μ

m exceeds a predetermined level.

(b) a processing unit connected to the output of the pulse height discriminator for processing the particle size distribution at a given time, based on the height of each pulse, producing a histogram of the airborne particle size distribution, and displaying the histogram on an output device;

(c) a reflector positioned in front of the beam blocking device in the path of the unscattered portion of the light beam for reflecting at least part of the unscattered portion in a second light path, and a second photodetector positioned to detect light reflected from the reflector, and/or

preferably including a power monitor connected to the output of the second photodetector for detecting decrease in light source output power, and an alarm device connected to the power monitor for producing an alarm signal if the light source power falls below a predetermined level, and/or

preferably a differential amplifier connected to the outputs of the two photodetectors for dividing the output of the first photodetector by the output of the second photodetector, the differential amplifier having an output connected to the pulse height discriminator.

(d) a transparent partition slide positioned between the sample area and the beam blocking device, and

preferably wherein the partition slide is removably mounted in the housing;

(e) the light source comprises a laser;

(f) the light source comprises an LED and

preferably also includes optical lens for shaping light from said LED into near collimated light;

(g) wherein said light source includes optical lens for shaping light and/or removing noise from said light beam.

3. An airborne particle detector system, comprising:

an outer housing having an air sample cell;

a light source on one side of the air sample cell area for sending a focused beam of light through the sample air, whereby portions of the beam of light are scattered at various angles by particles of various sizes present in the sample area, and an unscattered portion of the beam of light remains unscattered;

a beam blocking device on the opposite side of the air sample cell area for blocking at least the portion of the unscattered portion of the beam of light;

a first detector positioned in the light path after the beam blocking device for detecting a portion of the scattered light, and producing output pulses in which each pulse has a height proportional to particle size; and

a pulse height discriminator for obtaining the size distribution of airborne particles detected in the air sample at a given time.

4. The system claims in claim 3, further comprising one or more of the following features:

(a) an alarm unit for providing a warning signal if the number of particles within a predetermined size range exceeds a predetermined normal level within that size range, and

preferably wherein the alarm unit produces an alarm signal if the number of particles detected within a size range of approximately 1 to 7 μ

m exceeds a predetermined level;

(b) a processing unit connected to the output of the pulse height discriminator for processing the particle size distribution at a given time, based on the height of each pulse, producing a histogram of the airborne particle size distribution, and displaying the histogram on an output device;

(c) a reflector positioned in front of the beam blocking device in the path of the unscattered portion of the light beam for reflecting at least part of the unscattered portion in a second light path, and a second photodetector positioned to detect light reflected from the reflector, and

preferably including a power monitor connected to the output of the second photodetector for detecting decrease in light source output power, and an alarm device connected to the power monitor for producing an alarm signal if the light source power falls below a predetermined level and/or

preferably a differential amplifier connected to the outputs of the two photodetectors for dividing the output of the first photodetector by the output of the second photodetector, the differential amplifier having an output connected to the pulse height discriminator;

(d) a transparent partition slide positioned between the sample area and the beam blocking device, and

preferably wherein the partition slide is removably mounted in the housing;

(e) the light source comprises a laser;

(f) the light source comprises an LED; and

also preferably includes optical lens for shaping light from said LED into near collimated light;

(g) wherein said light source includes optical lens for shaping light and/or

removing noise from said light beam.

5. A detector apparatus for detecting airborne particles in a size range of approximately 1 to 7 μ

m in environmental air, comprising;

a light source for directing a focused beam of light through a sample of environmental air in a sample cell of cross-section not in excess of about 2 mm, whereby a first portion of said light beam remains unscattered and a second portion of said light beam is scattered at various angles by particles of various sizes present in the air sample, the scattering angle and scattering cross-section being dependent on the particle size;

a beam separating device for separating a predetermined part of the light beam corresponding to light scattered by particles within a predetermined size range from the remainder of the light beam and directing the separated part of the light beam along a light path; and

a first detector positioned in the light path for detecting said separated part of the light beam and producing a corresponding output signal including information on the number of particles in the light path within a predetermined size range.

6. The system as claimed in claim 5, comprising one or more of the following features:

(a) a control unit connected to the detector output for generating an alarm signal if the detected number of particles within a range of approximately 1 to 7 μ

m in size exceeds a predetermined value;

(b) a pulse height discriminator connected to the output of the detector for separating and counting output pulses from the detector based on pulse height, a processing unit connected to the output of the pulse height discriminator for processing the particle size distribution at a given time, based on the height of each pulse, and producing an output comprising a histogram of the airborne particle size distribution, and a display device connected to the output of the processing unit for displaying the particle size distribution histogram;

(c) a reflector positioned in front of the beam separating device in the path of the unscattered portion of the light beam for reflecting at least part of the unscattered portion in a second light path, and a second photodetector positioned to detect light reflected from the reflector and

preferably including a power monitor connected to the output of the second photodetector for detecting decrease in light source output power, and an alarm device connected to the power monitor for producing an alarm signal if the light source power falls below a predetermined level, and/or

preferably a differential amplifier connected to the outputs of the two photodetectors for dividing the output of the first photodetector by the output of the second photodetector, the output of the differential amplifier having an output connected to the pulse height discriminator;

(d) a reflector positioned in front of the beam separating device in the path of a part of the scattered portion of the light beam for reflecting at least part of the scattered portion in a second light path, and a second photodetector positioned to detect light reflected from the reflector;

(e) a transparent partition slide positioned between the sample area and the beam separating device;

(f) the light source comprises a laser;

(g) the light source comprises an LED and

preferably optical lens for shaping light from said LED into near collimated light.

7. A method of detecting airborne particles, comprising the steps of:

directing a light beam through a sample of environmental air in a sample cell of cross-section not in excess of about 2 mm such that a first portion of the light beam is scattered by particles present in the sample and a second portion remains unscattered;

receiving both portions of the light beam which have passed through the air sample and directing the light beam portions onto a beam blocking device;

blocking at least the second portion of the light beam at the beam blocking device and directing at least part of the first portion of the light beam onto a first detector;

measuring the pulse height of electrical pulses output from the first detector;

counting the number of pulses of each pulse height in a predetermined time interval and

converting the pulse heights to particle sizes.

8. The method as claimed in claim 7, comprising one or more of the following features or steps:

(a) producing an alarm signal if the number of pulses detected within a size range of 1 to 7 μ

m is exceeded;

(b) converting the data of number of pulses for each particle size into a histogram of the detected particle size distribution, displaying the histogram on an output display device, and repeating the conversion and displaying steps at predetermined intervals for new air samples;

(c) comparing the histogram to known bio-agent particle size distributions, and activating an alarm if the detected distribution matches any known bio-agent particle size distribution;

(d) blowing air through the sample area continuously to monitor changing conditions in a surrounding area;

(e) reflecting at least part of the second portion of the light beam onto a second detector, connecting the output of the second detector to a power monitor for detecting decrease in light source output power, and producing an alarm signal if the light source power falls below a predetermined level;

(f) placing a transparent partition slide between the sample area and beam blocking device to prevent dust from entering optical components.

9. A waterborne particle detector system, comprising:

an outer housing having an water sample cell area of cross-section not in excess of about 2 mm;

a light source on one side of the water sample cell area for directing a focused beam of light through the sample air, whereby portions of the beam of light are scattered at various angles by particles of various sizes present in the sample area, and an unscattered portion of the beam of light remains unscattered;

a beam blocking device on the opposite side of the water sample area for blocking at least the unscattered portion of the beam of light and directing at least part of the scattered light along a light path;

a detector positioned in the light path after the beam blocking device for detecting light directed by the beam blocking device onto the detector, and producing output pulses in which each pulse has a height proportional to particle size; and

a pulse height discriminator for obtaining the size distribution of airborne particles detected in the air sample at a given time.

10. The system as claimed in claim 9, comprising one or more of the following features:

(a) an alarm unit for providing a warning signal if the number of particles within a predetermined size range exceeds a predetermined normal level within that size range; and

preferably the alarm unit produces an alarm signal if the number of particles detected within a size range of approximately 1 to 7 μ

m exceeds a predetermined level;

(b) a processing unit connected to the output of the pulse height discriminator for processing the particle size distribution at a given time, based on the height of each pulse, producing a histogram of the airborne particle size distribution, and displaying the histogram on an output device;

(c) a reflector positioned in front of the beam blocking device in the path of the unscattered portion of the light beam for reflecting at least part of the unscattered portion in a second light path, and a second photodetector positioned to detect light reflected from the reflector and

preferably a power monitor connected to the output of the second photodetector for detecting decrease in light source output power, and an alarm device connected to the power monitor for producing an alarm signal if the light source power falls below a predetermined level and/or

possibly a differential amplifier connected to the outputs of the two photodetectors for dividing the output of the first photodetector by the output of the second photodetector, the differential amplifier having an output connected to the pulse height discriminator

(d) the sample cell includes an inlet and an outlet, and including water tight connectors on said inlet and outlet with

preferably the water tight connectors being removable.

(e) the light source comprises a laser;

(f) the light source comprises an LED and

preferably also includes optical lens for shaping light from said LED into near collimated light.

11. A detector apparatus for detecting waterborne particles in a size range of approximately 1 to 20 μ

m in water, comprising;

a light source for directing a focused beam of light through a sample of water air in a sample cell of cross-section not in excess of about 2 mm, whereby a first portion of said light beam remains unscattered and a second portion of said light beam is scattered at various angles by particles of various sizes present in the water sample, the scattering angle and scattering cross-section being dependent on the particle size;

a beam separating device for separating a predetermined part of the light beam corresponding to light scattered by particles within a predetermined size range from the remainder of the light beam and directing the separated part of the light beam along a light path; and

a detector positioned in the light path for detecting said separated part of the light beam and producing a corresponding output signal including information on the number of particles in the light path within a predetermined size range.

12. The system as claimed in claim 11, comprising one or more of the following features:

(a) a control unit connected to the detector output for generating an alarm signal if the detected number of particles within a range of approximately 1 to 20 μ

m in size exceeds a predetermined value;

(b) a pulse height discriminator connected to the output of the detector for separating and counting output pulses from the detector based on pulse height, a processing unit connected to the output of the pulse height discriminator for processing the particle size distribution at a given time, based on the height of each pulse, and producing an output comprising a histogram of the airborne particle size distribution, and a display device connected to the output of the processing unit for displaying the particle size distribution histogram;

(c) a reflector positioned in front of the beam separating device in the path of the unscattered portion of the light beam for reflecting at least part of the unscattered portion in a second light path, and a second photodetector positioned to detect light reflected from the reflector, and

preferably a power monitor connected to the output of the second photodetector for detecting decrease in light source output power, and an alarm device connected to the power monitor for producing an alarm signal if the light source power falls below a predetermined level and/or

preferably a differential amplifier connected to the outputs of the two photodetectors for dividing the output of the first photodetector by the output of the second photodetector, the output of the differential amplifier having an output connected to the pulse height discriminator;

(d) a transparent partition slide positioned between the sample area and the beam separating device;

(e) the light source comprises a laser;

(f) the light source comprises an LED; and

preferably optical lens for shaping light from said LED into near collimated light.

14. The method as claimed in claim 11, further comprising one or more of the following features or steps:

(a) an alarm signal if the number of pulses detected within a size range of 1 to 20 μ

m is exceeded;

(b) converting the data of number of pulses for each particle size into a histogram of the detected particle size distribution, displaying the histogram on an output display device, and repeating the conversion and displaying steps at predetermined intervals for new air samples;

(c) comparing the histogram to known bio-agent particle size distributions, and activating an alarm if the detected distribution matches any known bio-agent particle size distribution;

(d) blowing air through the sample area continuously to monitor changing conditions in a surrounding area;

(e) reflecting at least part of the second portion of the light beam onto a second detector, connecting the output of the second detector to a power monitor for detecting decrease in light source output power, and producing an alarm signal if the light source power falls below a predetermined level.

13. A method of detecting waterborne particles, comprising the steps of:

directing a light beam through a sample of environmental water in a sample cell of cross-section not in excess of about 2 mm such that a first portion of the light beam is scattered by particles present in the sample and a second portion remains unscattered;

receiving both portions of the light beam which have passed through the air sample and directing the light beam portions onto a beam blocking device;

blocking at least the second portion of the light beam at the beam blocking device and directing at least part of the first portion of the light beam onto a first detector;

measuring the pulse height of electrical pulses output from the first detector;

counting the number of pulses of each pulse height in a predetermined time interval; and

converting the pulse heights to particle sizes.

15. A detector system for detecting biological organisms or biological agents of predetermined particle size in a fluid comprising:

a housing having a passageway to allow for a fluid to flow through the housing;

a first light source for sending a light beam through the fluid flowing in the passageway;

a detector positioned in the light path of the first light source after said passageway for detecting and discriminating between particles of a selected size range in the fluid;

a second light source for sending light through said fluid passing in the passageway for exciting fluorescence in the particles in said fluid;

an elliptical mirror for collecting fluorescence light signals generated at one of the foci of the ellipsoid and directing the collected fluorescence light signals to a photo-detector located at the other focus of the ellipsoid;

a detector positioned in the light path of said second light source for detecting fluorescence of said particles; and

a control circuit connecting to outputs from said first and second detectors for generating an alarm output signal under selected conditions.

16. The apparatus of claim 15, comprising one or more of the following features:

(a) the first light source and a second light source comprise a single light source;

(b) wherein the fluid comprises air;

(c) wherein the fluid comprises water;

(d) wherein the fluid comprises air and the particles are of size from about 1 to about 7 microns;

(e) wherein the fluid comprises water and the particles are of size from about 1 to about 20 microns;

(f) wherein the second light source operates at a wavelength of about 270 nm to about 410 nm, and

preferably the second light source operates at a wavelength of about 370 nm to about 410 nm.

17. A filter unit for use with a particle detection sensor comprising:

a chamber;

a filter medium for restricting particles or clumps of particles above predetermined size from said chamber; and

an outlet from said chamber for connection to a particle detection sensor system.

18. A fluorescence/particle detection system comprising:

a passageway in which a fluid containing biological organisms or biological agents can flow;

a plurality of housing serially connected along said passageway;

at least one light source in each of said plurality of housing for sending light through the fluid for exciting fluorescence of said biological organisms or biological agents;

a detector positioned in the light path after said passageway for detecting the fluorescence and particle size of said biological organisms or biological agents and producing a corresponding output signal.

19. The fluorescence/particle detection system of claim 18, comprising one or more of the following features:

(a) wherein each light source produces light with a different wavelength;

(b) wherein each light source is tuned to produce light of an optimal excitation wavelength of one or more metabolites;

(c) wherein the wavelength of one light source is suitable for detecting riboflavin

(d) wherein the wavelength of one light source is suitable for detecting NADH;

(e) a long-wavelength optical pass filter in the path of the light beam before the fluorescence sensor to eliminate the excitation laser light;

(f) wherein said detector contains wavelength-selective elements to do spectral analysis of the light;

(g) wherein said plurality of sensors measure the fluorescence of the same batch of fluid;

(h) wherein each housing contains two light sources and one light source in each housing having a common wavelength to ensure consistent particle size measurements;

(i) wherein said fluid is air;

(j) wherein said fluid is water;

(k) wherein the wavelength of one light source is about 270 nm to about 410 nm.

20. A method of detecting biological organisms or biological agents, comprising the steps of:

directing a plurality of light beam through a fluid such that a portion of the light excites fluorescence of said biological organisms or biological agents;

detecting the fluorescence and particle size of said biological organisms or biological agents with a detector positioned in the light path and producing a corresponding output signal.

21. A fluorescence/particle detection system comprising:

an housing with a sample area in which a fluid containing biological organisms or biological agents can flow;

a plurality of light sources for sending light beams through the fluid to excite fluorescence of said biological organisms or biological agents;

an optical coupler in the path of the light before the sample area to modulate the plurality of light beams at different frequencies;

one or more detectors positioned in the light path for detecting the fluorescence and particle size of said biological organisms or biological agents and producing a corresponding output signal;

an control mechanism to differentiate the plurality of light beams based on the modulation frequency of the beam and to produce measurement of multiple fluorescence signals.

22. An particle detector system, comprising:

an housing having an air sample cell;

a light source on one side of the air sample cell area for sending a focused beam of light through the sample air, whereby portions of the beam of light are scattered at various angles by particles of various sizes present in the sample area, and an unscattered portion of the beam of light remains unscattered;

a reflection mechanism placed in the light path for deflecting into a second light path at least a portion of the light scattered at a certain range of angles;

a first positioned in the second light path for detecting a portion of the light and producing a corresponding output signal;

a second detector positioned in the light path after the reflecting mechanism for detecting a portion of the light scattered at angles not reflected by said reflection mechanism and producing a corresponding output signal.

23. The system as claimed in claim 22, comprising one or more of the following features:

(a) wherein said first detector is optimized for measuring particles from 0.1 μ

m to 1.0 μ

m in size;

(b) wherein said second detector is optimized for measuring particles from 1 μ

m to 10 μ

m in size;

(c) a mechanism for splitting the light beam into a plurality of beams placed in the light path after the reflection mechanism and before said first detector;

a third detector placed in the light path of one of the plurality of beams for detecting the fluorescence of particles in the sample area; and

preferably where said mechanism for splitting the light beam is a dichroic filter;

(d) wherein said second detector contains optics to focus the reflected portion of the second light beam;

(e) wherein said second detector contains optics to remove the unscattered portion of the second light beam before detection;

(f) wherein said light source includes optical lens for shaping light and/or removing noise from said light beam.