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WO2008083138A1 - Procédé et appareil de collecte de traces - Google Patents

Procédé et appareil de collecte de traces Download PDF

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Publication number
WO2008083138A1
WO2008083138A1 PCT/US2007/088789 US2007088789W WO2008083138A1 WO 2008083138 A1 WO2008083138 A1 WO 2008083138A1 US 2007088789 W US2007088789 W US 2007088789W WO 2008083138 A1 WO2008083138 A1 WO 2008083138A1
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WO
WIPO (PCT)
Prior art keywords
particles
chamber
gas
flow
particle
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2007/088789
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English (en)
Inventor
Robert Roach
Steven Shamash
Rafi Zchout
Gil Perlberg
Yarden Tsach
Roy Ornath
Offer Shemesh
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TRACEGUARD TECHNOLOGIES Inc
Original Assignee
TRACEGUARD TECHNOLOGIES Inc
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Filing date
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Application filed by TRACEGUARD TECHNOLOGIES Inc filed Critical TRACEGUARD TECHNOLOGIES Inc
Publication of WO2008083138A1 publication Critical patent/WO2008083138A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N1/22—Devices for withdrawing samples in the gaseous state
    • G01N1/2202—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling
    • G01N1/2211—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling with cyclones
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N2001/022—Devices for withdrawing samples sampling for security purposes, e.g. contraband, warfare agents
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N2001/028—Sampling from a surface, swabbing, vaporising

Definitions

  • the present invention relates to the field of detection systems, and more particularly to particulate collection and detection systems.
  • Explosive, toxic, nuclear, and biological threats typically are associated with trace particulates, as well as persons handling such items, and items later handled by such persons.
  • OPI Object Under Inspection
  • particle detectors are known.
  • One type of particle detector passes a hot gas over explosive particles or a sample on a fiberglass filter, which then increases the vapor pressure of the organic explosive, which is then subjected to ion mobility spectrometry.
  • Explosives detection for aviation security has been an area of federal concern for many years. Much effort has been focused on direct detection of explosive materials in carry-on and checked luggage, but techniques have also been developed to detect and identify residual traces that may indicate a passenger's recent contact with explosive materials.
  • the trace detection techniques use separation and detection technologies, such as mass spectrometry, gas chromatography, chemical luminescence, or ion mobility spectrometry, to measure the chemical properties of vapor or particulate matter collected from passengers or their carry-on luggage.
  • Parallel efforts in explosives vapor detection have employed specially trained animals, usually dogs, as detectors.
  • the effectiveness of chemical trace analysis is highly dependent on three distinct steps: (1) sample collection, (2) sample analysis, and (3) comparison of results with known standards.
  • a lower detection limit of 10-20 grams might be reasonable.
  • the screening process seeks to identify microscopic traces, with no reasonable lower limit of detection imposed within the constraints of acceptable false positives.
  • One approach is to direct passengers through a portal, similar to a large doorframe, that contains detectors able to collect, analyze, and identify explosive residues on the person's body or clothing.
  • the portal may rely on the passenger's own body heat to volatilize traces of explosive material for detection as a vapor, or it may use puffs of air that can dislodge small particles as an aerosol.
  • a handheld vacuum "wand" may be used to collect a sample. In both cases, the collected samples are analyzed chemically.
  • a different approach is to test an object handled by the passenger, such as a boarding pass, for residues transferred from the passenger's hands.
  • the secondary object is used as the carrier between the passenger and the analyzing equipment.
  • the olfactory ability of dogs is sensitive enough to detect trace amounts of many compounds, but several factors have inhibited the regular use of canines as passenger explosives trace detectors. Dogs trained in explosives detection can generally only work for brief periods, have significant upkeep costs, are unable to communicate the identity of the detected explosives residue, and require a human handler when performing their detection role. In addition, direct contact between dogs and airline passengers raises liability concerns.
  • Some versions could simultaneously detect other threats, such as nonmetallic weapons.
  • trace detection techniques would likely also detect bulk quantities of explosives, and may alert screening personnel to security concerns about a passenger who has had contact with explosives but is not actually carrying an explosive device when screened.
  • a potential complication of explosives trace detection is the accuracy of detector performance. False positives, false negatives, and innocuous true positives (those which have a legitimate explanation) are all challenges. If the detection system often detects the presence of an explosive when there actually is none (a false positive) then there will be a high burden in verifying results through additional procedures. Because of the large volume of air passengers, even small false positive rates may be unacceptable.
  • the system fails to detect the presence of an explosive (a false negative) then the potential consequences may be serious. Assuming the system has adequate sensitivity to detect explosives traces in an operational environment, the detection threshold or criteria required for an alarm can generally be adjusted, enabling a tradeoff between false positives and false negatives.
  • One type of collection apparatus includes hand held machines, such as described in US
  • Other collection systems include chambers into which the luggage is inserted, such as described in US 5,942,699 and US 6,324,927 to Ornath et al., US 4,580,440 to Reid et al., US 5,162,652 to Cohen et al., US 3,942,357 to Jenkins et al., US 3,998,101 to Bradshaw et al., the disclosures of which documents is incorporated herein by reference.
  • the luggage is preferably sealed in the chamber and various methods are used to dislodge vapors from the luggage.
  • the volume of air in these chambers is generally too large such that some contaminants having low dilution rates are not detected.
  • US 4,909,089 suggests suppressing air jets directed at the inspected human's face.
  • US 4,987,767 describes a sampling chamber in which air jet streams are injected from a plurality of ducts in different sides of the chamber so as to induce air flow from the floor of the chamber to its ceiling. This air flow sweeps over individuals or objects passing through the chamber.
  • US 6,073,499 to Settles the disclosure of which is incorporated herein by reference, describes a portal which relies upon the heat of the human body to generate flow of air towards the ceiling of the portal.
  • One embodiment of the invention provides integrated particle collection and detection systems.
  • Prior systems and methods employed separate collection and detection systems, often with a manual physical transfer of concentrated particles from the collector to the detector. This was justified because the detector systems are highly evolved specialized analytical instruments, typically with few moving parts, while the particle collection devices were highly mechanical devices, with different types of service and maintenance requirements, and therefore an integration of the systems would likely lead to decreased availability of the system and perhaps reduced aggregate reliability.
  • This embodiment of the present invention exploits the increased efficiency of an integrated system designed specifically for this purpose, and therefore operating with lower cost, less manual intervention, improved reliability, and more efficient detection.
  • the various embodiments of the invention can be used to extract, collect and analyze various types or traces and particulates, including those which pose security hazards, and other types, including biological, chemical, contamination, dust, ash, source or origin-specific particles, agricultural chemicals, geological particles, forensic analysis, and the like.
  • the particle analyzer therefore becomes an automated part of the particulate collection machine cycle, eliminating the need for an operator to physically remove a filter of collected particles for analysis in a separate analyzer and thus reducing risk of particle loss (and environmental contamination) during transfer and external contamination of a sample.
  • One of the few remaining manual tasks in trace detection is the manual placing of collected traces from an OUI in a trace analyzer.
  • To more fully automate the process, and reduce risk of human error it is greatly desirable to integrate a detector with a collector.
  • the integration of devices may also reduce minimum cycle time, and therefore increase screening throughput.
  • a preferred analyzer for explosive particle detection is an ion mobility spectrometer (IMS), which passes a small volume of a hot gas over a particle sample to volatilize the residues, and compares ion mobility for the sample with a control having known composition.
  • IMS ion mobility spectrometer
  • the sample In order for this system to operate optimally, the sample must be as concentrated as possible, and thus it is infeasible to employ IMS on a simple vapor plume from an OUI, without particle collection, even if the total amount of residue sample is the same.
  • the IMS itself takes time, and incurs cost, so the number of analyses should be minimized. Therefore, it is preferred to perform a single analysis for an entire OUI, rather than serial analyses of partial samples.
  • One particular issue for integrating the collection and analysis systems is the vast difference in gas volumes; the collection system typically employs gas flows to extract and suspend the particles to be collected, and therefore uses many liters of gas during a typical extraction cycle; the analyzer, on the other hand, passes a few milliliters at most over the sample to volatilize the analyte.
  • the process typically requires two discrete phases, a first phase wherein the particles are freed from their supporting surfaces, suspended, and transported in a volume of air, to a concentrator (typically a porous filter which filters the particles and allows filtered air to pass), and a second phase wherein the filter is subjected to the analysis with the small volume of heated gas.
  • a concentrator typically a porous filter which filters the particles and allows filtered air to pass
  • the filter material may be formed of an organic synthetic fiber, which is pretreated to remove or prevent generation of interferents in the detection process.
  • the filter may be formed of Nomex® fiber, which is treated by heating to remove substances which potentially interfere with detection of explosive traces. See, US Pat. App. Pub. 20060192098A1, which is expressly incorporated herein by reference in its entirety. Cellulose like fibers may also be suitable. See, US Pat. App. Pub. 20050288616A1, which is expressly incorporated herein by reference in its entirety. See also, US Pat. App. Pub. 20020148305A1, incorporated herein by reference.
  • the filter may also be formed of fiberglass.
  • the area of the collection filter is also preferably small. However, this is a contradictory requirement for filtering a large volume of rapidly flowing air from the collection system.
  • One way to bridge these differences is to employ a technique to preferentially separate flows of the collection air stream having a high concentration of particles from flows which do not.
  • the low particle concentration flow may be used as a bypass, reducing the flow volume load on the filter, and even enhancing the pressure differential across the filter.
  • the portions may be separated by a number of means. For example, the particles are typically denser than the gas in which they are suspended, and therefore the particles may be separated inertially.
  • One inertial separation technique employs a vortex, which forces dense particles in a tube or funnel outward toward the wall.
  • any change in flow rate or flow direction may be used to proportionate the collection stream.
  • the collection system is preferably designed to avoid undesired or uncontrolled changes in flow vectors, which may lead to particulate deposition in locations other than the filter.
  • thermophoretic force may also lead to particle movement, through the so-called thermophoretic force.
  • the presence of temperature gradient imposes thermophoretic force on the particle.
  • the force generated by the electromagnetic radiation is referred to as the photophoretic force.
  • thermophoretic force acts at heat releasing (absorbing) particles near the interface between two media with different thermal conductivities. This force is caused by the induced temperature gradient which is proportional to the rate of heat release (absorption) by the particle.
  • thermophoretic force is proportional to the rate of heat release (absorption) by the particle, and its direction depends upon the sign of the parameter kappai-kappa2, where kappai is thermal conductivity of a host medium and kappa 2 is thermal conductivity of the adjacent medium.
  • kappai thermal conductivity of a host medium
  • kappa 2 thermal conductivity of the adjacent medium.
  • thermophoretic force is further related to another issue presenting itself in a particle collection system, that of dislodging particles which adhere to surfaces and fabrics of the OUI.
  • a gas boundary layer will tend to be created at the particle surface, possibly reducing its adhesion to the carrier material.
  • one aspect of an embodiment of the invention is to use heat and thermal gradients to advantage to optimize the particle collection process. It is noted that any heating process must be judiciously applied and carefully controlled in order to avoid damage to the OUI.
  • a specific resonant frequency of atoms sought to be detected it is possible to define a specific resonant frequency of atoms sought to be detected, and to specifically excite these molecules to heat the particles.
  • This excitation will, in general, be more effective at creating specific particle-ambient thermal gradients than flowing heated air; however, it is important to avoid excitation at frequencies and power levels which will interact with macroscopic elements or otherwise damage the OUI.
  • electromagnetic excitation is an important element of the collection process, it may be undermined by intentional or innocuous shielding, and therefore if employed, a system is preferably employed to detect electromagnetic field perturbations indicative of macroscopic interactions with the OUI, which will be generally unintended. These perturbations may be detected by an antenna or antenna array.
  • the optimal excitation frequency for each molecule or composition to be detected will often be different, and therefore it may be preferred to scan over a range of frequencies, for example using a chirp, adaptive frequency generator, spread spectrum or the like.
  • the system employed to excite the particles will appear similar to a system seeking to detect the particles in situ, however, such systems will generally differ.
  • a detector requires a specific readout, which must be controlled, while the excitation system requires no such readout or control.
  • the conditions of excitation should also be uniform and selective in an analyzer, while in a simple exciter, the fields need not be uniform, and the selectivity limited to avoid damage to the OUI.
  • Another force available for collecting particles and separating them from the bulk of gas flow is the electrostatic force.
  • the particles may be initially in a charged state and adherent to an oppositely (or diaphoretically induced) charged substrate, and therefore may be dislodged from the substrate through electrostatic and/or charge neutralization effects.
  • the particles once suspended in a gas flow, the particles may also be concentrated or proportioned electrostatically. Uncharged particles may be selectively charged through various means, including tribo-electric effects, adjacent ionized particles, alpha or beta rays, or the like. Once charged, the particles may then be steered or adhered through electrical and/or magnetic fields.
  • a particularly advantageous embodiment provides a collection filter which is charged to an opposite polarity than the particles entrained in a gas stream, with the chamber walls charged the same as the particles, and the charged filter is disposed in an area of reduced flow velocity (e.g., expanded cross sectional area).
  • the filter is preferably located coaxially with the inlet flow vector.
  • particles will be inertially concentrated toward the core of the flow, while the electric field will repel the particles from the walls of the chamber toward the filter in the center. This allows a portion of the gas stream distant from the filter and proximate to the charged wall to bypass the filter, reducing the required flow capacity of the filter.
  • the flowing gas behind the filter may be used to create a relative vacuum behind the filter, increasing the pressure differential, and thus the flow through the filter relative to an unassisted embodiment.
  • one aspect of the invention is to eliminate unintended electrostatic charges to reduce adhesion of the particles to objects and surfaces.
  • reduce static charge there are typically two choices: reduce the resistance between the charged object and its adherent surface, or supply an sufficient opposite charge to neutralize the residual.
  • reduce static charge often an increase in humidity is effective, since the moisture permits even small amounts of ionic salts to conduct.
  • An antistatic agent may also be supplied, for example a quaternary ammonium salt, though the introduction of such compounds may pose additional problems.
  • electrostatically charged objects it is also possible to expose electrostatically charged objects to ions, such as alpha rays, which ionize the air, increasing its conductivity and thereby facilitating electrostatic discharge.
  • ions such as alpha rays
  • the electrostatic dissipation effects may be employed, for example, in the chamber and/or in the transport conduit.
  • ferees and effects may also be employed to fractionate the air flow between particle enriched and particle depleted portions, which will effectively reduce the required filter size and increase the permissible amount of collection gas stream during an extraction cycle.
  • a filter as a particle collection device is not mandatory, and indeed a collection plate, liquid or gas volume may also be used.
  • a collection plate liquid or gas volume may also be used.
  • an attractive force between the particles and a surface may be sufficient to separate the entrained particles from a gas flow.
  • a collection surface has the advantage that it can be cleaned and generally reused, while a filter tends to accumulate various particles, and therefore has a limited life, leading to a consumables expense in testing.
  • the system may segregate particles using various effects.
  • One embodiment provides a series of with cascading filters, having different characteristics. For example, explosive trace particles tend to be very small, and even if large particles are present, they are associated with small particles. Thus, by pre-filtering large particles, such as natural and/or synthetic fibers, before collecting particles on an analyzing filter, the operation of the system may be improved.
  • the particles of interest may be segregated from other particles by various physical effects, such as aerodynamics, electrostatics, momentum effects, thermophoretic, photophoretic and/or acoustophoretic effects.
  • a collection liquid is advantageous because of the surface tension forces which will retain a particle once it touches the surface, assuming that the liquid wets the particle. Indeed, by selecting an appropriate liquid, a fractionation of particles can occur, distinguishing particles which are wet by, or even soluble in, the liquid and those which are not. It is noted that once the particles are wet by the fluid, they (or their vapors) must be released or testable in situ. Therefore, it is preferred that any such fluid surfaces have minimal volume. For example, a vapor phase material can be flushed though a portion of the collector, which has a chilled surface.
  • the chilled surface will condense an amount of the vapor, generally in a uniform pattern, though it may also be possible to micro-pattern the fluid deposition by altering the surface properties of the chilled surface (e.g., with a selective fluid-phobic or fluid-philic coating), which in turn will reduce the volume of fluid interacting with the particles further.
  • the fluid may then be allowed to evaporate after the particle collection has occurred, or may be sampled, with the particles, by the analyzer, so long as the fluid is non- interfering with the analysis.
  • Fluids may include water, organics (hydrocarbons, alcohols, ketones, etc.), hydro-fluorocarbons, etc.
  • a gaseous carrier phase may be employed especially where the particles are fractionated into a relatively small volume, and preferably present as a bolus for a short period.
  • the carrier gas may be direct (without intermediate deposition) or directly, after desorption from a surface.
  • an electrostatic plate may selectively adsorb particles from a large gas volume, and later release the particles (e.g., by reversing the charge polarity) into a smaller gas volume or directly into the sampling gas.
  • a "sticky" surface such as an adhesive or adherent polymer, e.g., a poly-methyl-phenyl siloxane.
  • the sticky material may be selective for the particles of interest, rather than all particles, though at low particle densities this may not be a critical factor. At higher particle densities, a more selective adhesion will maintain more selective binding capacity.
  • a non-outgassing film adhesive surface may be exposed to particles, which will adhere to the surface, and which may then be exposed directly to the hot gas stream for sampling in an IMS detector.
  • IMS detector such as made by Barringer or Ion Track Instruments, Inc.
  • LDS Laser Detection Systems
  • NQR nuclear quadrupole resonance
  • microcantelever sensors analyte-specific FETs or other semiconductors
  • canines or other in vivo biological sensors or the like may be used. See Table 2.
  • the present invention also provides a system and method for decontaminating an object which is contaminated with particles.
  • the decontamination process is adaptive, and requires that samples from the object subject to decontamination be periodically sampled to determine whether the process is complete. Therefore, the chamber should provide at least one state wherein particles, if present, are efficiently transported to a detector.
  • the extraction procedures are conducted maximally, until the residual particle release is below a threshold.
  • the efflux from the chamber need not be directed to an analyzer, and therefore flow rates and volumes need not be controlled.
  • efficient use of compressed gas is generally preferred, so an optimal pattern of gas flows is provided to reduce the time and gas consumption of the process. In an airport environment, the types of articles under investigation tend to have consistent characteristics, and therefore the present invention provides optimized methods for collecting particles from such articles.
  • a regime of opening (or partially opening) a carry-on bag, directing sampling air flows, thermal processing (radiant and/or convected heat), electric fields, static abatement treatments, etc. may be used.
  • a suction wand may be selectively applied to openings of the bag or OUI may be employed as the article is being prepared.
  • a series of samples from the same passenger may be collected sequentially, and together analyzed, since the typical purpose of the screening is to identify persons of interest, and not to identify explosives or contraband per se.
  • contraband should be interdicted, this is typically detected through radiographic methods (X-ray testing), and thus the particulate collection systems are intended to identify persons who have handled or been associated with explosives or contraband, not the contraband itself.
  • X-ray testing X-ray testing
  • articles under inspection are prepared and placed into an extraction chamber.
  • the extraction chamber provides a contained space in which gas flows (including pressurization/depressurization, vortical and swirling flows, shearing flows, shock and expansion wave flows, etc.), and optionally thermal effects, electromagnetic effects, static neutralization effects, vibration, and the like, are applied, in a control sequence and amplitude.
  • gas flows including pressurization/depressurization, vortical and swirling flows, shearing flows, shock and expansion wave flows, etc.
  • thermal effects including pressurization/depressurization, vortical and swirling flows, shearing flows, shock and expansion wave flows, etc.
  • thermal effects including pressurization/depressurization, vortical and swirling flows, shearing flows, shock and expansion wave flows, etc.
  • thermal effects including pressurization/depressurization, vortical and swirling flows, shearing flows, shock and expansion wave flows, etc.
  • thermal effects including pressurization/depressurization, vortical and swirling flows,
  • Vibration may also be used to assist in dislodging particles from surfaces.
  • the vibration particularly helps particles to migrate from deep within an OUI to near the surface, where air flows can then carry the particles out of the article and then chamber.
  • vibration will cause rubbing of surfaces, which will physically transport particles like a diffusion process and sometimes increase static electrical charges through tribo-electric effects. This can be counteracted as discussed below.
  • the frequency, duration, amplitude, and other characteristics of the vibration may be controlled, especially in the acoustic range, such as through electromagnetic and electrostatic speakers.
  • an oscillating table may be implemented by one or more eccentric mass motors or hydraulic or pneumatic actuators.
  • electrostatic and/or piezoelectric transducers are employed in the ultrasonic frequency range.
  • a chirp, white or pink noise, adaptive resonance-seeking treatments, or other acoustic or vibrational environment may be applied.
  • the OUI or gas flows may be heated by one or more of heating the air entering the chamber, radiant heating from one or more walls of the chamber, electromagnetic waves exciting materials within the chamber, or the like.
  • a water mist may be sprayed on the surface of an OUI.
  • a 2.4 GHz microwave emitter can then be employed to excite the water to form a heated steam.
  • This steam advantageously transfers heat to other cooler structures within the chamber (presumably the OUI), and will also dissipate static charges.
  • the electromagnetic field within the chamber may be optimized to selectively heat the water mist, without substantial risk of damage to the OUI.
  • electromagnetic radiation which specifically targets the composition of the particles sought to be detected may have particular utility, in heating them, increasing their rate of volatilization, and likely decreasing their adhesion to supporting surfaces.
  • an NMR-type analysis of an OUI may be conducted to detect substances of interest.
  • the sampling chamber may also be integrated with an X-ray or CAT system to simultaneously or at least within an integrated environment extract particles and image the OUI contents.
  • an X-ray image will clearly establish the presence and arrangement of electrically conductive materials within an OUI. If performed first, this will allow an estimate to be made whether any such materials are present which will adversely interact with a microwave or other electromagnetic excitation.
  • a process may be provided in accordance with an embodiment of the invention to determine whether there are arrangements of materials within an OUI which will interact with electromagnetic waves, and further, to predict a nature of that interaction. Then, based on the estimate may be used to alert the screener to manually inspect the bag and/or remove the article identified.
  • a key ring within baggage may selectively interact with a standing wave.
  • the electromagnetic field is adapted to place a null in the plane of the ring, or otherwise to shield the ring from the field, then the remainder of the OUI may be illuminated with the field.
  • the field may be created with a phased array antenna, preferably on all sides, so that the field may be controlled with high precision, including higher order effects.
  • Another aspect of the invention integrates a particle analyzer within an extraction chamber. In this case, one purpose of the chamber is to facilitate migration of particles from within an OUI to its surface.
  • a surface particle analyzer such as a scanned laser
  • the particles may also be dislodged from the OUI surface to a chamber surface.
  • the scanned laser detector system may, for example, have sufficient sensitivity to reliably detect a single particle having picogram or lower mass. More typically, however, a minimum sensitivity may be set at a few detected particles, since a single particle threshold will probably lead to a high level of false positives, while a true positive will likely be associated with multiple particles presented for detection.
  • Laser remote chemical sensing systems are known, and need not be described in great detail herein.
  • the optical path of the laser will generally be folded, and, for example, the laser will generally skim the surface at an oblique angle rather then be incident normal to the surface.
  • Another option is to seek to dislodge particles from the OUI for deposition on the walls of the chamber.
  • the analysis phase may occur after removal of the OUI from the chamber, leaving a relatively large void volume.
  • the analyzer may be a separate module inserted in the chamber after removal of the OUI, which then scans the walls of the chamber for particles.
  • the laser analyzer may also be integrated with the chamber walls, or simply operate through the walls, for example through windows or conduits.
  • the laser detection is generally non-destructive, it may be conducted prior to flushing particles from the chamber for IMS detection downstream, thus permitting dual detection functionality.
  • the collection filter, surface, or flow may be subject to multiple detection/analysis phases, for example laser detection and IMS.
  • Permitting multiple detection/analysis devices to operate in tandem is advantageous because it maintains the particulate extraction device as a component of a general purpose screening system for various contraband or the like, such as drugs, radioactive substances, chemical or biological threats, etc.
  • a particulate extraction chamber is provided to accommodate, e.g., luggage in an airport.
  • One or more substance detectors may be incorporated into a particle extraction system for in-situ analysis of traces from the external and internal portions of the article being inspected.
  • a laser based detection system is placed for sensing in the chamber such that the laser beam or a curtain is aimed at the membrane cavity or internal portions of an exhaust tube.
  • the laser can be used to scan the filter or its mount and or surrounding in continuous or pulsed fashion.
  • Such a system could be used instead of, or to supplement, a particle collection filter.
  • the possible elimination of a filter permits a simplified air flow path, and improved system cleanliness.
  • traces can be identified by an in-situ detection process, saving analysis and operational time and eliminating operator related errors.
  • One aspect of the invention provides an automated cleaning cycle for the chamber, either as a regular part of operation, or when contamination is detected.
  • the cleaning cycle is typically performed with an empty chamber, and thus the gas flow pattern will nominally differ from a particulate extraction cycle.
  • the air flow path for cleansing the system includes different orifices, flow rates, and exhaust ports.
  • the volume of air used is intentionally constrained, in part because of the need to filter the effluent.
  • no such limitations are apparent, except perhaps a supply of compressed gas.
  • one goal is to avoid particle deposition on the chamber walls (unless the system is intentionally designed to deposit particles on the chamber walls); while during a cleaning the goal is to dislodge particles which are already adhered.
  • gas must flow from the chamber to the exhaust port, toward the filter and/or detector.
  • a gas flow can be initiated directly within the exhaust conduit, and the filter and subsequent flow obstructions may be removed from the flow path, leading to higher peak flow rates and particulate dislodgement forces.
  • the Tunable Diode Laser (TDL) or Laser Detection System (LDS) can also be used to verify system cleanliness by doing a fast sweep of a laser curtain over the complete or portions of the membrane and exhaust tubes.
  • the filter can be designed as a labyrinth, where the laser is positioned in areas where the flow is slower, in order to increase "hit rate" of the laser of the traces.
  • In situ laser detection may be implemented by applying the following design schemes to the system:
  • the laser beam detects traces while they are being extracted or transported from one location to another.
  • the laser beam varies diameter, or curtain, where the width of the beam is larger then its thickness. 3.
  • the laser beam detects traces while they are in mid air, or in flight either in a laminar flow pattern or in a turbulent flow regime.
  • Other means of particle detection include Gas Chromatography, mass spectrometry, electron capture detection, electron spin resonance, and sundry methods based on fluorescence of the sought after materials.
  • the various detectors are modular and/or interchangeable.
  • the collected particles are accumulated on a filter or surface disposed at or near an outlet of the chamber.
  • a stationary or moving sticky tape may be disposed inside the chamber at a location where particles are collected.
  • the sample of particles can be placed directly with the sticky tape or the filter onto the detector or a swab can be used to transfer the accumulated particles onto the detector substrate.
  • the particle detector can be integrated with the sealed chamber by way of having the particle detector sealed within the suction vacuum enclosure.
  • An opening in the chamber wall allows particles to move from the chamber onto the particle detector.
  • It is a further object of an embodiment of the invention provides a trace particle extraction method, comprising providing a chamber, having an object inspection region; controlling a flow of pressurized gas into the chamber through at least two different types of orifices over time; and concentrating particles released from at least one object for analysis.
  • a still further object of an embodiment of the invention provides a computer readable medium having persistently stored therein instructions for controlling an automated system for a trace particle extraction system having a chamber with an object inspection region therein, to separately control a flow of pressurized gas into the chamber through at least two different types of orifices over time, to extract particles for analysis and to transport extracted particles to an analysis region.
  • a flow of gas through at least one of the two different types of orifices may vary over time during an inspection of an object such that a respective object is subject to a plurality of peak and trough pressure variations.
  • the flow of gas through the at least two different types of orifices may be independently controlled.
  • a flow of gas through the at least two different types of orifices may be independently controlled and have respective flow patterns which are synchronized.
  • At least one of the at least two different types of orifices may be adapted to release a flow of gas for extracting particles from at least one object.
  • At least one of the at least two different types of orifices may be adapted to release a flow of gas for transporting extracted particles from at least one object to a collection region.
  • a flow of gas from at least one of the at least two different types of orifices may be varied in dependence on at least one characteristic of an object being analyzed.
  • a sensor adapted to sense at least one characteristic of at least one object being analyzed, may be provided.
  • the system may further comprise an object analyzer adapted to determine at least one characteristic of at least one object being analyzed.
  • the object analyzer may be internal or external to the chamber. It is noted that a plurality of objects may be provided in the chamber concurrently, and therefore may be analyzed or subject to a process together.
  • the chamber may have a working volume defined by at least one rigid wall with a predetermined configuration.
  • the object is, for example, fluid permeable, and the object may be permeated with the fluid.
  • the chamber may have a wall treated to reduce a particle adhesion.
  • the port may comprise a selectively operable valve.
  • the port may communicate with a relative vacuum.
  • the port may comprise a filter adapted to retain particles entrained in the fluid.
  • the system may further comprise at least one filter disposed in fluid flow path through said at least one port.
  • the at least one filter may comprise a plurality of different types of filters each adapted to trap a different type of filtrate. The plurality of different types of filters may differentiate types of filtrate by particle size and/or based on a physical state of the filtrate.
  • the at least one inlet may comprise a supersonic jet and/or a subsonic jet, or both at least one supersonic jet and at least one subsonic jet.
  • the plurality of different types of inlets may comprise at least one jet which induces a flow perpendicular to a wall of the chamber.
  • the plurality of different types of inlets may comprise at least one fan jet for selectively inducing a flow of fluid tangential to a surface of said chamber.
  • the control may control a plurality of valves, in a sequence dependent on time.
  • the control may control a plurality of valves, in a sequence dependent on at least one pressure sensor, which for example, may be an electronic pressure sensor, mechanical pressure sensor, or other type..
  • the control may control a plurality of valves, dependent on an output of at least one temperature or temperature gradient sensor.
  • the control may control a plurality of valves, according to optically determined particle trajectories.
  • the inlets may comprise a plurality of types of jets, at least one type of jets being subdivided into jets which are separately sequenced.
  • the flow of fluid through at least one outlet may be selectively controlled. It is another object of an embodiment of the invention to provide a security system, comprising an imaging system, producing at least one electromagnetic image of at least one object under inspection; a particle extraction system, having a controllable air supply; and a control for said controllable air supply, to selectively alter said air supply in dependence on the at least one electromagnetic image of the at least one object under inspection.
  • the imaging system may be external to the particle extraction system, further comprising a communication network adapted to communicate between the imaging system and the control.
  • the system may further comprise an image analyzer for determining at least one characteristic of at least one object represented in an image.
  • the particle extraction system may have a plurality of orifices, wherein a gas flow through the plurality of orifices is independently controlled in dependence on the imaging system.
  • the imaging system may generate a signal dependent on a size of an object or a plurality of objects.
  • the imaging system may generate a signal dependent on a shape of an object or a plurality of objects.
  • the imaging system may generate a signal dependent on a radio-density of an object or set of objects.
  • the imaging system may generate a signal dependent on second object within a first object.
  • the at least one object may be positioned within the particle extraction system in dependence on an output of the imaging system.
  • the system may further comprise a particle extraction jet, adapted to extract particles from at least one object within the chamber.
  • the air amplifier jet may comprise a coanda effect jet.
  • the air amplifier jet may induce a flow parallel to a wall of the chamber.
  • the air amplifier jet may induce a circulating flow within the chamber.
  • the optical detector may direct an energy beam toward a detection surface, to detect particles adhered to said detection surface.
  • the optical detector may direct an energy beam toward a detection space, to detect particles suspended in a gas within said detection space.
  • the optical detector may direct a dispersed stationary energy beam toward a detection region.
  • the optical detector may direct a concentrated scanning energy beam toward a detection region.
  • the optical detector may sense optical characteristics of explosive traces at more than one optical wavelength.
  • the optical detector may comprise a laser.
  • the optical detector may comprise a spectrometer.
  • the optical detector may produce an image of at least one optical characteristic across the sensing region.
  • It is a still further object of an embodiment of the present invention to provide a trace particle extraction method comprising providing a chamber having an inlet connected to a pressurized gas supply through at least one controllable valve; and selectively varying a flow of gas through the valve from said pressurized gas supply into said chamber over time based on a control signal, to provide at least two phases of operation, a first phase adapted for dislodging trace particles from supporting surfaces, and a second phase adapted for transporting dislodged trace particles to a detection region.
  • the at least one controllable valve may comprise at least two controllable valves, said at least two controllable valves leading to ports into said chamber having respectively different gas flow patterns, at least one flow pattern comprising a high speed jet having a major flow axis directed to a bulk volume within said chamber normal to a wall of said chamber, and at least one jet having a major flow axis directed parallel to said wall of said chamber.
  • the system may further comprise a gas egress conduit, communicating between said chamber and a particle concentration region, said particle concentration region comprising a bypass, wherein a first portion of gas passing though said gas egress conduit is presented for analysis by an analyzer, and simultaneously a second portion of gas passing through said gas egress conduit bypasses the analyzer.
  • the second portion may have a lower concentration of particles than said first portion.
  • At least one of a thermophoretic, electro-phoretic, acoustophoretic, opto-phoretic effect may be used to proportionate particles within a gas stream.
  • the at least one controllable valve may be controlled adaptively in dependence on at least one characteristic of at least one object in the chamber.
  • the at least one controllable valve may be controlled according to one of a set predetermined sequences.
  • the at least one controllable valve may comprise at least two controllable valves, separately controlled by the electronic control.
  • the at least one controllable valve may comprise at least two independently controllable valves controlled to provide different flow patterns.
  • the gas injection port for example, may be a permanently mounted quick-connect connector which, when connected, retains itself in position, and which can be readily disconnected.
  • the particle collection plenum may be a hollow region which interconnections various regions and compartments of the luggage, and which can be exhausted to collect a sample of particles at various locations within the luggage.
  • Another object of an embodiment of the invention provides an article of luggage, comprising a first exterior sheet having a high permeability for particles, and a second exterior sheet having a lower permeability for particles, wherein when an exterior pressure is lower than an interior pressure of the luggage, particles are selectively withdrawn from the luggage through the exterior sheet having high permeability.
  • the high permeability external sheet may also be used to inject air into the luggage.
  • the article of luggage may further comprise an identification tag which identifies characteristics of the luggage relating to particle collection. The identification tag may be remotely readable.
  • the gas injection port and/or the particle collection plenum may comprise a quick release connector.
  • the article of luggage may further comprise an injected gas distribution plenum.
  • the article of luggage may further comprise a gas injection jet.
  • the luggage may be constructed substantially of radio lucent materials.
  • the article of luggage may further comprise an identification tag which is remotely readable through a non-contact reader, and may be adapted to convey information identifying the luggage by owner and luggage type.
  • the article of luggage may be provided in combination with a pressurized gas source adapted to be connected to the gas injection port, wherein at least one flow characteristic of the pressurized gas may be controlled in dependence on the luggage type received from the identification tag.
  • the article of luggage may comprise both a gas injection port and a particle collection plenum, wherein the particle collection plenum may be adapted to capture particles from within the luggage suspended in the gas injected through the gas injection port.
  • the article of luggage may further comprise at least one of, or both, a gas injection port and a particle collection plenum.
  • the particle collection plenum may be adapted to capture particles from within the luggage suspended in the gas injected through the gas injection port.
  • the article of luggage may be configured to permit mechanical redistribution of particles contained within any compartment to an
  • the invention may further comprise interacting a bulk gas flow with an aerodynamic structure within the bounded enclosure, to generate a turbulent layer proximate to the wall dependent on the bulk gas flow.
  • the aerodynamic structure may comprise a turbulator, i.e., a device which interacts with a fluid flow over at least a range of flow conditions to induce turbulent flow conditions.
  • the wall may comprise pores through which a flow of gas passes. A net flow of a gas through the wall may be generated. At least one of an electrostatic force and a thermophoretic force between the extracted particles and the wall may be generated.
  • Vibrations may be induced in the wall, to oscillate particles which contact the wall.
  • the force created by the gas flow may act to suspend particles adherent to the wall into the bulk gas flow particles adherent to the wall.
  • the force may act to maintain particles in suspension in the bulk gas flow.
  • the gas flow may be substantially normal to the wall to reduce particle adhesion to the wall.
  • a cyclically varying flow of gas over time may be provided to induce a time-varying force in particles.
  • the gas flow may be provided through at least one pulsatile jet.
  • a filter for capturing traces of organic materials within a trace collection system, comprising an open matrix comprising at least one material configured as a mechanical filter which selectively absorbs organic materials carried in a gaseous stream passing through the open matrix.
  • Another object provides a method for capturing traces of organic materials within a trace collection system, comprising providing an open matrix comprising at least one material configured as a mechanical filter which selectively absorbs organic materials carried in a gaseous stream passing through the open matrix; and passing a gas flow containing organic materials through the open matrix.
  • the organic materials may comprise plastic explosives and/or organic nitrates.
  • the filter may comprise a matrix material which selectively absorbs explosive material vapors and/or explosive material particles.
  • the filter may comprise a woven or non- woven fabric or an open cell foam.
  • a chiller may be provided, adapted to reduce a temperature of the open matrix by at least 5C.
  • the open matrix may comprise activated carbon, capton, and/or p-84.
  • the matrix material may be stable to a temperature of at least 200C, and a heater provided for heating the filter to at least 175C to release absorbed organic materials into a surrounding gas without decomposing the matrix material.
  • the particles may be adsorbed at least in part based on an electrostatic charge.
  • the at least one sensor may be associated with a first security device, and the particle collection device comprises a second security device separate from the first security device.
  • the at least one object may be transported from the first security device to the second security device.
  • the received data may be dependent on a humidity associated with the at least one object.
  • the second security device may be controlled in dependence on the set of control parameters.
  • the processor may predict, based on the input, whether a particle collection device will be able to effectively screen the at least one object for at least one predetermined type of particle.
  • the processor may control a placement of the at least one object within a particle collection chamber in dependence on the input.
  • a particle collection cycle of the second security device may be controlled.
  • the received data may be based on determined particle migration characteristics.
  • a system and method may also be provided for determining characteristics of objects that make special procedures useful to perform an inspection for particles.
  • the object may be fully enclosed or hermetically sealed, or be otherwise isolated from treatment conditions or particle collection systems and apparatus.
  • the protocol may be altered.
  • alternate or additional screening may be indicated, manual or automated steps undertaken to remediate the impediment to particle collection or analysis, or a different system or apparatus employed to process the object.
  • a system and method may also be employed to determine whether there are interfering conditions, whether a false -positive test result will occur, or whether there is a significant likelihood of contamination of equipment or the environment, with steps taken to avoid or overcome such conditions or their adverse effects.
  • a laptop computer or camera may be difficult to process according to a protocol designed for other types of carry-on luggage. Therefore, once the existence of such items or their characteristics are determined, an alternate protocol may be employed, which, for example, provides specific access to interior compartments or directs air flows in a particular manner to optimize the process, without causing damage or undue risk or damage to the object under inspection. It is another object of an embodiment of the invention to provide a method for validating use of a particle collection device, comprising receiving data from at least one sensor, adapted to sense at least one characteristic of at least one object; and predicting, based on the received data, whether a particle collection device will be able to effectively screen the at least one object for at least one predetermined type of particle.
  • the sensor may be adapted to sense at least one of a size, a weight, a volume, a density, a temperature, a humidity, a static charge, and a cleanliness of at least one object.
  • An indication may be produced of a location of a portion within the at least one object which cannot be effectively screened.
  • the at least one characteristic of the at least one object may be remediated, to increase an effectiveness of a screening of the at least one object. It is noted that the remediation may be provided for all objects, or selected objects.
  • the particle collection device may have a plurality of different operating regimes, further comprising the step of selecting an operating regime in dependence on the received data.
  • the at least one sensor may comprise an x-ray densitometer.
  • the at least one sensor may produce an x-ray image of the object.
  • other types of electromagnetic images of the object may be produced, without limitation for example, optical, infrared (nar or far), ultraviolet, microwave or terahertz radiation image, thermal neutron bombardment image, hyprespectral image, fluorescence imaging, magnetic resonance or quadrupole resonance image, electron spin resonance image, radioactive decay or isotope-specific radiation image, or the like.
  • the at least one sensor may produce a computed tomographic image.
  • the at least one sensor may comprise a neutron scanner.
  • the at least one sensor may comprise an optical camera.
  • the at least one sensor may comprise an electrostatic potential probe.
  • the at least one sensor may estimate a permeability of the at least one object.
  • the at least one sensor may estimate a density of the at least one object.
  • the at least one sensor may estimate an internal configuration of the at least one object.
  • the at least one sensor may determine at least a set of external dimensions of the at least one object
  • the tracer may be humidity.
  • the tracer may be at least one of hydrogen, helium, argon, xenon, krypton, oxygen, nitrogen, carbon dioxide, perfluorocarbon, hydrofluorocarbon, hydrocarbon, alcohol, ether, ketone, aldehyde, derivatized aromatic, and nitrous oxide.
  • the chamber may be sealed during at least one phase of operation.
  • a tracer level sensor may be provided within an object under inspection.
  • a tracer level sensor may be provided external to an object under inspection.
  • the analyzing may estimate at least three volumes of distribution and respective permeabilities of tracer within an object under inspection, each volume having different characteristics.
  • the pressurizing may be controlled in dependence on the analyzing.
  • the chamber may be sealed during at least one phase of operation, such that an increased molar amount of gas injected into the chamber leads to an increase in pressure, the tracer comprises a difference in a level of a naturally occurring component of air between the injected gas and an atmospheric gas, the pressurizing step is controlled in dependence on the analyzing step, and the collecting step collects particles extracted from the object under inspection, at least in part, by the injected gas, during a phase of operation when the chamber is not sealed.
  • the collecting may comprise inducing a flow of the fluid medium at a high flow rate, and said analyzing gas is heated and flows at a flow rate lower than a conveyance flow rate of the fluid medium, wherein an analyte from the particles is concentrated within the heated analyzing gas with respect to the fluid medium.
  • the particles may comprise a composition having a low vapor pressure under ambient conditions, further comprising, after collecting the extracted particles, inducing conditions which increase a volatility of the composition.
  • the collecting may comprise inducing a fluid medium flow pattern adapted to deposit suspended particles on the target.
  • the collecting may comprises inducing an electrostatic field adapted to deposit suspended charged particles on the target.
  • the particles may be adhered to the target by at least one of an electrostatic force, a surface-active adhesive force, and a mechanical entanglement with an open target matrix structure.
  • the analyzing may comprise performing at least one of ion mobility spectrometry, gas chromatography, mass spectrometry, fluorescence, electron capture detection, laser scanning, an oxidation-reduction reaction, chemiluminescence, surface acoustic wave detection, micro- cantilever detection, field ion spectrometry, laser induced breakdown spectrometry, atomic emission spectrometry, Raman spectroscopy, laser induced fluorescence, arc emission spectroscopy, spark emission spectroscopy, Fourier transform spectroscopy, surface enhanced Raman scattering, and surface Plasmon resonance.
  • the target may remain in fixed position during both the collecting and the automatically initiating steps.
  • the plurality of inlets may produce a laminar and/or turbulent flow of working fluid having a bulk flow or stream trajectory substantially parallel to the floor.
  • the method may further comprise the step of extracting particles from the at least one object using a flow of working fluid from at least one additional inlet, the at least one additional inlet producing forces on particles associated with the at least one object adapted to dislodge them and entrain them in the flow of working fluid.
  • the at least one additional inlet may produce a flow of working fluid having a bulk flow having a substantial component normal to a surface of the at least one object.
  • the induced flow of working fluid beneath the suspended at least one object may have a stream profile adapted to entrain small particles substantially without settling on the floor.
  • the induced flow may provide a cyclic variation in pressure adapted to extract particles from the at least one object.
  • Fig. 1 shows a block diagram of an embodiment of the invention
  • Fig. 2 shows a side view of an OUI in a rectangular sealed chamber for particulate extraction in accordance with an embodiment of the invention
  • Fig. 3 shows a side view of an OUI in a conical sealed chamber for particulate extraction in accordance with an embodiment of the invention
  • Figs. 4A and 4B respectively show a closed and open circular recessed jet valve
  • Fig. 5 shows a side view of an OUI in a conical sealed chamber having top and bottom rows of jets for particulate extraction in accordance with an embodiment of the invention
  • Fig. 6 shows a perspective view of a rectangular sealed chamber, having a plurality of different jet types, for particulate extraction in accordance with an embodiment of the invention
  • Figs. 7A, 7B and 7C show, respectively, a side view, top view of floor, and top view of ceiling of an OUI in a rectangular sealed chamber having a plurality of jet types, for particulate extraction in accordance with an embodiment of the invention;
  • Figs. 8 and 9 represent various particle detectors in accordance with embodiments of the invention;
  • Figs. 10 and 11 show timing diagrams for extraction sequences in accordance with embodiments of the invention.
  • Figs. 12A and 12B show examples of aerodynamic particle concentration and methods of reducing particle contamination of conduit walls
  • Figs. 13, 14, and 15 show, respectively, a centrifugal, thermophoretic and acoustic wave filter in accordance with the present invention
  • Fig. 16 shows a representative particle density profile for an acoustic wave filter in accordance with the embodiment of Fig. 15;
  • Fig. 17 shows an electrostatic particle focusing filter in accordance with the present invention
  • Fig. 18 represents a particle pre-concentrator apparatus ion accordance with the present invention.
  • Fig. 19 shows a network of screening and security devices in accordance with the present invention
  • Figs. 2OA and 2OB show embodiments of side intake Coanda effect jets
  • Fig. 21 shows an embedded flush Coanda effect jet
  • Figs. 22A-22D show respectively top and side views of particle extraction chambers having Coanda effect jets with side or bottom exhaust ports.
  • the present invention provides, in one embodiment, a component of a security system used to inspect objects for traces of hazardous materials.
  • a typical embodiment of the system is used for airport security luggage screening by detecting traces of explosive materials within and outside of the luggage. It is understood that these traces may be solid (e.g. particles), liquid (e.g. droplets) or gaseous (e.g. vapors) in nature.
  • the system can be used to inspect traces of other materials within the luggage and on the luggage exteriors.
  • the same system can be used to inspect a luggage article simultaneously for traces of explosives, drugs, biological, chemical or nuclear hazardous materials.
  • the system is predominantly used for luggage inspection yet is not limited to this application. Different embodiments of the system may be used for other security applications, like cargo inspection and other embodiments of the system may be also used for non-security applications like food industry content of package detection.
  • the working medium is air and therefore reference is made many times to air. It should be noted, however, that other gases or even certain liquids can be used in other embodiments of the invention.
  • One embodiment of the present invention is intended as a particulate extraction and analysis system for screening carry-on luggage and parcels at airports, known as the "CompactSafeTM” system.
  • This system generally comprises a sealed chamber, a particle extracting and transporting unit, a particle collection unit and a particle detection unit.
  • UAI Object Under Inspection
  • the inspected object can be placed on an object support unit detached from the chamber floor.
  • the system has resources operable to blowing air (or another gas) onto the object for extracting any particles on the object's surface or inside the object (when an unsealed object is involved), into the air volume of the chamber. Particles in the air volume of the chamber are transported via the air blowing system and directed onto a particle collection area.
  • Fig. 1 illustrates a functional block diagram of the system.
  • the cycle starts with the particle- extracting unit 3 seeking to extract particles from inside and outside the OUI 1 by various patterns of gas flow around and, in some cases, through the OUI 1.
  • the gas flows seek to release particles sticking to the OUI 1 exterior surface, by blowing air onto the OUI 1.
  • the extracted and released particles enter the air volume 10 of the sealed chamber 2 and are transported through the chamber air volume 10.
  • a particle collection unit 4 is used to collect as many particles as possible for detection. The number of particles lost by sticking to the chamber interior and landing on the chamber floor are sought to be minimized, and the number of particles reaching the particle detector 6 is maximized.
  • the particle detector 6 is most commonly a commercial product capable of detecting minute particle traces of predefined material, such as explosives or nuclear, biological or chemical threats. Traces of particles reaching the detector may include a variety of particles of different materials, yet the particle detector is designed to detect only a limited number of materials of interest for the inspection.
  • a chamber-cleaning cycle may be initiated with a chamber cleaning unit 7 to blow air inside the empty chamber to clean the chamber from residual particles which may remain, and to prepare the system for the next cycle of inspection.
  • Other means of cleaning the chamber include using liquids, irradiating with heat or other contaminate neutralizing radiation, and manual cleaning.
  • various explosive compositions are fluorescent, and may be decomposed by exposure to such radiation.
  • Another embodiment provides a surrogate object to fill a portion of the void volume within the chamber during a cleaning cycle.
  • object may, for example, have an internal or connected compressed gas supply, and direct gas jets outward toward the walls of the chamber.
  • the object may also have a surface configuration which efficiently deflects the jets emanating from the wall of the chamber back toward the wall, to thus supply a cleaning stream.
  • the streams need not be entirely gaseous, and in fact may comprise liquids.
  • the liquids may comprise surfactants, detergents, solvents, abrasive solids, or other components.
  • water derived from environmental humidity released by a compressor may be employed, thereby reducing a need for a condensate discharge and separate liquid supply.
  • a drying cycle is generally also implemented.
  • a drying cycle typically employs heated, dry compressed air.
  • the block depicting the System contains blocks representing a particle extraction unit 3, a particle transporting unit 4 and particle collection unit 5, which leads to the particle detector 6/analysis unit.
  • FIG. 2 illustrates a cross sectional view of one embodiment of the system.
  • An OUI 1 is placed on the object placement shelf 11.
  • the OUI 1 may be a traveler's luggage, electronic device, food package or any other package or object.
  • the object placement shelf 11 has large open areas, to allow the blown air to reach the bottom of the OUI 1.
  • Jets 12 of blowing air, emanating from various locations on the chamber 2 walls, produce a three dimensional pattern of air in the chamber 2, which acts to separate particles from their supporting surfaces, and suspend them in the flow, which vents through the particle transporting unit 5, i.e., an exhaust conduit, to the particle detector 6/analysis unit.
  • the jets are further adapted to extract and cause particles to migrate from within the OUI 1, toward open areas, where they can then be suspended in the air flow.
  • a particle filter 14 is provided in the exhaust path from the air outlet 13 to concentrate and capture particles, while allowing the large volume of particle-depleted air to flow out of the system.
  • the particle filter 14 may be detachable from the chamber 2, in which case it is transferred to a separate or independent particle detector 6/analyzer.
  • the particle detector 6/analyzer may also be integrated, in which case detachment of the particle filter 14 may be unnecessary.
  • the goal of the system is to maximize the number of particles reaching the detector.
  • the following characteristics of the system determine the level of system performance:
  • Chamber structure Size, shape, and mode of operation.
  • Jets number, type, position, orientation and mode of operation.
  • Particle detection Detection technology, local detection, off line detection.
  • Chamber cleaning Method, jet surface cleaning related to particle detection.
  • the chamber 2 It is considered sealed, in that influx and efflux of gas occurs only through a discrete and controlled pathways.
  • the chamber receives air through jets or other inlets to both extract particles from their supporting surfaces on and within the OUI 1, and transport them to the transporting elements, and then to the detection elements.
  • the chamber is sealed in order to isolate the OUI 1, and air flow pathway, from any peripheral effects and particles, which are not present on or within the OUI 1. Further, in the event that the OUI lis contaminated, the sealed chamber 2 prevents contamination of the environment at large.
  • the chamber 2 is also sealed to prevent inadvertent leakage of pressurized air within the chamber during system operation.
  • the chamber is subjected to a cleaning cycle, in order to remove residual particulates from within the chamber 2, particle transporting elements 5, and relevant portions of the detection system 6.
  • a cleaning cycle in order to remove residual particulates from within the chamber 2, particle transporting elements 5, and relevant portions of the detection system 6.
  • it may be permissible to subject a subsequent OUI 1 to testing, without cleaning, since the detector 6 is sensitive and specific for the particulates of interest only.
  • it may be useful to subject a series of OUFs to extraction, and thereafter analyze the aggregate collected particles together in a single operation. Practical and operational considerations lead to a chamber structure that is sufficiently large to incorporate OUI 1 of a given maximum dimensions yet is not excessively large, and thus require excess air volume for testing.
  • a chamber 2 size that is substantially bigger than the size of the inspected object reduces system efficiency by transporting the particles a longer route through the air volume of the chamber. Therefore, a plurality of systems of different size may be provided, adapted for OUFs of different sizes or other characteristics.
  • the classification of objects is quite limited, for example no more than three classes.
  • the shape of the inside of the chamber is not rectangular.
  • the interior of the chamber is shaped to efficiently direct the particles in the air volume of the chamber to the particle detection area.
  • the chamber may also have an adaptive shape, for example having an inner mantle which conforms to the OUI 1.
  • the chamber 2 walls do not contact the OUI 1, in order to allow extraction of particles from all portions of the OUI 1. It is further possible to conduct the particle extraction in multiple phases, for example a first phase in which air jets are focused at or close to the OUI 1 surface, to penetrate deeply within, and subsequently displaced from the surface, to suspend particles at the or near the surface of the OUI 1 in an air flow.
  • Fig. 3 illustrates another embodiment of the chamber shape.
  • the inside walls of the chamber 2' are shaped like a truncated cone, and the air outlet 13 is located at the truncated end of the cone.
  • the cone shaped chamber 2' structure is used to direct the airflow inside the chamber to the air outlet 13 and thus increase the number of particles landing on the particles filter 14.
  • the air blown by the air blowing jets 12 array placed on the wall at the base of the cone shaped chamber 2' direct the airflow onto the OUI 1 disposed on the object placement shelf 11.
  • the extracted particles from within the OUI 1 and the released particles from the exterior surface of the OUI 1 are transported through the sealed chamber 2' air volume 10 and directed to the exhaust conduit to land on the filter 14 surface.
  • a fraction of the particles may land on the chamber 2, 2' walls and thus prevented from directly reaching the particle filter 14.
  • the number of particles not ultimately reaching the filter 14 can be minimized by coating the inside surface of the chamber 2, 2' with a slippery, non-sticky material like Teflon.
  • Another way to maximize the number of particles reaching the particle detector 6 is to generate an interfacial layer of gas moving away from, or along, the wall of the chamber or conduit, thus providing a force for repelling the particles. This may be generated by, for example, an array of small orifices of a porous wall (a transpiring wall) subject to a higher pressure externally than internal, the thermophoretic force, or other forces.
  • a chamber and conduit cleaning process may be applied prior to particle detection.
  • the cleaning cycle is conducted by a cleaning unit 7 routinely, and the particles which migrate through the system during this cycle are analyzed.
  • the cleaning cycle bypasses the filter 14 and detector 6/analyzer, and thus permits flow conditions which are non-optimal for the filter 14 and detector 6/analyzer, but which more effectively flush the remainder of the system of contaminants. 4.
  • Jets Air jets pressurized by a compressor or source of compressed air or other gas, for example to about 8 bar (about 120 psi), from a reservoir or compressor, is a substantive force applied to the OUI 1 to dislodge the particles and transport them for analysis.
  • Other forces include vibration, the inertial forces incurred in placing the OUI in the chamber, and possibly in a preparation step, e.g., opening of a bag.
  • the inlet air for the compressor is preferably filtered and purified, to avoid hydrocarbons, NOx, amines, excess humidity, aerosols, and other potentially interfering components.
  • the jets may be selectively configured to produce different air flow patterns within the chamber and different forces on the OUI and particles during dislodgement.
  • the pressure and flow in any or all jets may be modulated during a cycle, to produce a dynamic pressure and flow pattern within the chamber.
  • the back pressure through the exhaust conduit may also be modulated, thus permitting a further degree of control. It has been found, for example, that in the preferred embodiment, the chamber depressurizes to a 0.85 atmosphere absolute pressure through the exhaust conduit more slowly than it pressurizes from an 8 atmosphere pressure source through the jets, likely due in part to the larger pressure difference.
  • the speed of pressurization and depressurization (and consequently the mass flow rates) are but one parameter related to the efficiency of the system.
  • the type of jets substantially affect the performance of the system.
  • the jets are available with various patterns, which vary by volume of air permitted at a respective pressure, symmetry pattern, angular dispersion, induction of movement of air already within the chamber, etc.
  • Various jet types, as well as variations in their flow rates, and time varying functions thus provides a broad range of flexibility for optimizing the performance of the system.
  • the working gas from these jets also serves to pressurize the chamber.
  • the preferred pressure is anywhere from 0.1 to 0.5 bars gage pressure. However, depending on the OUI, a higher pressure may be used if found to be more effective.
  • the high pressure allows the working gas from the chamber to enter the OUI and mix with the air already within.
  • the air within the chamber suspends particulate matter released from the OUI.
  • the chamber also has means of introducing heat to the interior surfaces to increase particle desorption or de-adhesion. Such means include heating the working gas before it enters the chamber, direct heating of the walls of the chamber, and heating a plate on which the OUI rests in the chamber.
  • Indirect means while not included with the preferred embodiment, could also be used, such as low level microwave radiation.
  • Other means of energizing the materials within the OUI include using an ionized working medium and vibration.
  • air jets can be used in an alternating manner, or vibrations may be generated or transmitted from a plate or tray on which the OUI sits.
  • the tray could be suspended on a series of springs, which, along with the tray have a known aggregate spring constant in the three different directions.
  • Combinations of pulsed jetting at various frequencies from the sides and top and bottom of the chamber may be used to induce a resonant vibration of the OUI and tray.
  • the resonant frequencies may be deduced from accelerometer readings from the tray or computed from the known spring constants and measured mass of the tray and OUI.
  • the plate or tray mentioned above could be any supporting structure which holds the OUI above any jets or ports which may be on the chamber floor.
  • the supporting structure can be of any construction or shape which permits jet flow to impinge on the bottom surface of the OUI and allows particles to exit any opening on the bottom of the OUI.
  • the structure for example could be a "smart tray", which includes sensors and/or actuators which may be useful in intelligently optimizing the process.
  • the pressure in the chamber can be controllably released. In this step, some of the mixed air containing interior particles from within the OUI is extracted.
  • the preferred embodiment uses a vacuum pump to lower the pressure in the chamber below atmospheric pressure, through the exhaust conduit, so that more air is extracted than was put into the OUI.
  • a cyclone can be induced (indeed, the cyclone may be a natural result of any slight instability or geometric nonuniformity within the chamber inducing the converging flow along the ceiling to begin to spin just as flow out of a kitchen sink naturally flows in a whirlpool fashion) within the chamber to force an outward particle trajectory.
  • This system also creates an axial flow in the center of the chamber at the core of the cyclone so that lighter gases, aerosols, or particles will be likewise be captured and directed toward an exhaust port.
  • the axial flow is downward toward an exhaust port in the floor.
  • one embodiment of the invention heats the air either before, or as it enters the chamber, to at least counteract the expansion cooling, and preferably to increase the temperature of the OUI, for example by about 1OC.
  • Jets can be classified into three categories: classical open-hole jets, shaped jets and flow inducing jets.
  • Open-hole and shaped jets are conduits having openings for release of high-pressure air, preferably stored in a tank, and modulated with a pressure valve. Opening the valve instigates airflow from the high-pressure source to the lower pressure environment within the chamber.
  • Shaped jets differ from open-hole jets in that open-hole jets have single cylindrical bores, while shaped jets have other shapes and/or multiple interacting air flow pathways. Different geometrical openings and relationships are used to shape the air- flow pattern of the jet.
  • Flow inducing jets also called air amplifiers
  • air amplifiers For example those utilizing the Coanda effect, create air motion in their surroundings.
  • air amplifiers Using a small amount of compressed air as their power source, air amplifiers pull in large volume of surrounding air to produce high volume high velocity outlet flows.
  • Some air amplifiers can create output flows up to 40 times their consumption rate and substantially increase the efficiency of the system.
  • Coanda jets are those exemplified, for example, by the "air Amplifiers" by Exair Corp (11510 Goldcoast Drive, Cincinnati, OH 45249-1621, www.exair.com) where the flow induced through the jet is coaxial with the tube axis
  • the type of Coanda jet preferentially embodied here induces the air at 90 deg to the tube axis. This may be done as shown in Figure 20 or it may be done with recessed holes and the air in the chamber is sucked into the jet as shown in Figure 21.
  • Shock waves are large amplitude waves propagating at supersonic velocity, across which pressure, density, particle velocity and/or temperature change in a positive step function. Shock waves may be classified as normal or oblique according to whether the orientation of the surface of abrupt change is perpendicular (normal) or in angle (oblique) to the flow. Oblique shock waves may be generated, for example, by using over or under expanded nozzles as is well known in the art, as well as by having a supersonic air jet impact a wedge immersed in the stream. A breathing cycle utilizing a cyclical increase and decrease of air pressures is utilized for assisting the extraction of particles from within the inspected object.
  • Cyclical air pressure variation is also used for impacting the exterior surfaces of the OUI for releasing particles adhered to the object surface into the air flow. Jets also play a role in moving particles in the air enclosed inside the object, keeping particles aloft in the volume of the chamber, removing particles adhering to the surfaces of the chamber, collecting and directing the particles to the detector collecting area and cleaning the chamber.
  • Jets may operate variably as a function of time.
  • a jet can be operated continuously or cyclically.
  • multiple jets can have a combined scanning operation employing any desirable functions of time for the jet scanning. Jet operation as a function of time is discussed in detail in subsequent sections.
  • a scan function for a respective jet can result from a mechanical variation in the orientation of a jet over time, or a pneumatic change affecting the flow pattern emanating from an orifice. For example, by bringing together a plurality of independently modulated air flows, under conditions wherein they do not reach homogeneity by the terminus of the orifice, the resulting flow pattern from the orifice will vary depending on respective pressures of the contributing orifices.
  • One of the specially shaped jets that can be used in an embodiment of the compact safe system for a full surface air sweep is the circular recessed jet depicted in Figs. 4A and 4B depicting the circular recessed jet in the open and closed valve positions.
  • Fig. 4A illustrates the circular recessed jet - valve in a closed state.
  • the jet assembly screws onto the chamber 2 wall, such that the bottom of the jet assembly is flush with the inner surface of the chamber 2 wall.
  • the high-pressure air 27 is contained in the air supply and does not reach the circular recessed jet.
  • the force of the retaining spring 22 pulls the jet opening cover 23 to close the opening and high pressure air cannot flow in this position into the inside of the chamber 2.
  • Fig. 4B illustrating the circular recessed jet- valve in an open state.
  • the air pressure on top is sufficient to overcome the retaining spring 22 pulling force applied on the jet cover 23 opening and allowing-high speed airflow 28 into the chamber 2 volume.
  • the geometry of the jet causes the airflow to remain along the walls collecting particles and debris along the way.
  • jets may be used in every embodiment of the system, since jets have several functions in the operation of the system, and different jets, configured in assorted arrangements, operating in diverse modes are used to provide optimum performance for the system.
  • the multiple types of jets and the key role that jets are playing in the system allow having a multiplicity of embodiments associated with jets. Since various jets are independently controllable, according cycle parameters, it is possible to adapt the cycle in dependence on characteristics of the OUI, determined either before the object is placed in the chamber, or while it is there-within. In either case, an estimate of a relevant characteristic of the OUI is made, and in dependence thereon, the cycle patter is modified in a cycle controller.
  • the cycle controller is, for example, a computer receiving input from one or more sensors, and an output for controlling the various valves and other cycle control components.
  • a tracer is placed on the OUI, and the cycle pattern varied based on the response of the tracer.
  • the tracer is innocuous and readily detected during the process.
  • fluorescent labeled polystyrene micro-beads, titanium dioxide, or other nontoxic, environmentally acceptable tracer may be employed.
  • a set amount of tracer may be intentionally placed deep within an OUI.
  • a probe may submit the contents of the OUI to a vacuum, to sample internal particles directly. The process conditions are then controlled until a predetermined amount of the tracer is recovered. If the tracer is not recovered within a present time, the OUI may be flagged for a manual inspection.
  • a plurality of different tracers the set of which used varying every test, may be employed.
  • beads selected from a group of 25 bead types, each having two fluorescent dyes may be mixed in sets of 2-4 types of beads, leading to a low probability than the bead set used in any given test could be predicted.
  • each airport or screening station could employ its own bead type.
  • Alternate tracers may also be employed.
  • Fluorescent particles are advantageously readily bleached by UV, ozone, etc., and thus decontamination of the chamber from tracer is readily achieved.
  • fluorescent particles prior to a test, fluorescent particles are placed at supposedly inaccessible location of bag. During the extraction process, fluorescent particle releases are monitored. Treatment continues and perhaps gets more aggressive until a desired portion of tracer particles are recovered. The test environment is reset by a bleaching phase between tests.
  • the tracer may be inserted on a "wipe", doped flow of gas, or by direct particulate insertion.
  • a wipe is, for example, a non- woven sheet, having deposited thereon with a predetermined amount of particles, designed to emulate a standard condition. The wipe may be used to transfer the particulates onto contents of the OUI, or itself be inserted, and remain in the OUI during the test.
  • the volume of luggage may be estimated according to various methods. For example, the density of the bag estimated, and its mass determined. Likewise, using size estimates or sensors, the volume may be measured or estimated directly.
  • a further method involves the use of tracers. If luggage is placed in a container of known volume, and then a tracer gas injected into that volume, and immediately mixed and sampled (i.e., within seconds), the dilution volume of the tracer in the container will represent the remaining volume, excluding for the OUI.
  • Suitable tracers may be, for example, H 2 , He, Ar, N 2 , O 2 , CO 2 , CO, CH 4 , C 2 H 6 , C 2 H 4 , HCCH, CH 3 CH 2 OH, H 2 O, etc. Rare gases may also be used as tracers.
  • the tracer may be used as a positive control for the detection process.
  • Humidity may be used as a marker to determine the rate of mixing.
  • Humidity H 2 O vapor
  • a technique allows determination of a more optimal machine breathing cycle. In this case by varying the parameters of the breathing cycle, it is possible to see which parameters are more efficacious.
  • humidity is used as a marker, it is important to ensure that the OUI does not change the humidity, or if it does, that the effect is controlled.
  • Using humidity as a marker it has been found that in two different breathing cycles, one with and one without shaking, there is a very noticeable difference between shaking and non-shaking, showing a dramatic example of the effectiveness of shaking as a mixing mechanism.
  • humidity has been found to be an effective surrogate marker to permit process optimization.
  • the use of tracers also permits an estimate of a volume of distribution within the luggage, which represents the equilibration dilution. If, for example, a portion of the luggage is isolated from external gas, it will not be diluted in that volume.
  • This volume is useful for inferring the extent and restriction on gas flow paths within the OUI, which can then be used to qualify the OUI for various treatments and select an optimal treatment to extract the particles of interest.
  • These parameters may then be used to estimate a degree of various treatments necessary to sample the luggage for particulates therein.
  • Such treatments may include pressure variations (extent, profile), mechanical agitation, etc.
  • the testing process need not be limited to a single ascending or descending dilution, and may, in fact, include concentration discontinuities of a number of tracers.
  • the tracer technique is employed as a fast estimate, and therefore the final concentration of constituent gases is predicted based on dynamic change rates.
  • This technique may also be used to indicate when luggage has a sufficient isolated volume that it should be manually checked.
  • the present invention therefore provides an inline and automatic trace collection and detection process.
  • the OUI is placed in an incoming tunnel, where the OUI is prepared for the inspection, its size and weight measured, and optionally a tracer placed in a location considered inaccessible.
  • the size and weight are used to characterize the OUI, to define certain variable parameters of the process.
  • An automated data transfer and data synchronization process with other screening equipment (imaging) may also be used to determine process parameters, i.e., sequencing, length and jet type. It is noted that in many cases, the amount of compressed air available for a test is limited, and even if freely available, the greater the volume of gas used, the greater the amount of gas that must be filtered to recover the particles. Therefore, the process is typically not simply maximized for all OUI, or prolonged for objects considered difficult, since this will generally not be optimal.
  • a further type of jet protrudes from a wall of the chamber, and optionally is retractable and/or repositionable.
  • the OUI is placed in the chamber.
  • a jet nozzle close to, or at the OUI surface.
  • the protruding jet may be self balancing, and extend until a tip touches a surface.
  • a sensor or camera may be used to define a placement of the jet.
  • a protruding jet nozzle may induce various flow patterns, for example generating flows normal to, or parallel to, the OUI surface.
  • a related protruding element from a chamber wall is a suction port.
  • a selective withdrawal of gas may be implemented locally on the surface, for example to efficiently draw particles from an open gap of an OUI.
  • a suction device may also be present as a hose, intentionally placed within an OUI or at a portal, to selectively draw gas, and entrained particulates, from the OUI.
  • the hose is coupled, for example, to a moveable or non-movable surface of the chamber, and is manually placed by an operator of the equipment.
  • a hose may optionally include one or both of a suction port and an efflux port.
  • a gas source placed within an OUI not produce disruptive gas flows which might be objectionable, and therefore a diffuser is preferably provided to direct gas flows in various directions simultaneously, rather than axially.
  • a circular dispersion jet design may be used.
  • a suction port preferably also employs a diffuser, to reduce the possibility of clogging during use.
  • the OUI After removal from the extraction chamber, the OUI is placed in an outgoing tunnel, and held for a short period, until detection determines if the OUI is clear or requires further inspection.
  • jet arrays are placed on all the chamber walls excluding the wall of the outlet. This allows “blasting" the object from all directions and directing the extracted particles towards the air outlet.
  • FIG. 5 illustrates a cross section of the chamber 2' with the truncated cone shape, depicted in Fig. 3.
  • Each one of small squares 12', 12" represents a jet.
  • the jets may be of different class 12', 12".
  • the jets on the wall opposite to the outlet 13 may be the air amplifiers to apply a higher air thrust.
  • the top row jet 12' and bottom row jet 12" as well as the right row and left row jets (not shown in Fig.
  • Jets are placed on all the chamber 2' walls to blow air on the OUI 1 from different directions.
  • the jets on the top, bottom and sidewalls have an angular orientation in a direction that blows the extracted particles toward the particle collection area at the air outlet 13.
  • the circular recessed jets discussed in the preceding section are utilized.
  • most of the jets are disposed on the top surface of the chamber while the vacuum port is located at the center of the chamber floor. This arrangement allows utilizing the assistance of gravitational force in the operation of the system.
  • FIG. 6 illustrating perspective view of the chamber showing an example of the distribution of various types of jets mounted on the inside surfaces of the chamber.
  • the main flow of air in the chamber is top to bottom.
  • An array of circular recessed jets 32 and highspeed jets 31 are mounted on top.
  • the exhaust conduit, connected a vacuum port 34, is placed in the center of the floor and high-speed jets 31 blowing upward.
  • Additional corner fanjets 33 are placed in each of the four corners on the chamber 2 floor.
  • Figs. 7A, 7B and 7C depict three views showing the airflow inside the chamber.
  • Fig. 7A illustrates a front view of the air streams inside the chamber according the embodiment depicted in Fig. 6.
  • FIG. 7B illustrating a top view of the of the chamber floor. Air streams from corner fanjets 33 flowing towards the vacuum port 34 at the center of the floor are shown in this view. These airflows are combined with the bottom sweeping airflows coming from the top jets to sweep the bottom of the inspected object and the chamber floor.
  • Fig. 7C illustrates the top view of the chamber top inside surface. The ten circular recessed jets 32 on the top surface sweep the inside top surface of the chamber 2 and the air streams flow to the core of converging air streams in the center and flow down towards the OUI 1.
  • any combination of the large variety of available jets may be used in other embodiments of the system, which, for example, may lead to maximizing the number of particles extracted from the object and reaching the detector.
  • the embodiments of the system using air jets are not limited to air jets. Jets of gas that is different from air may be used as well in some embodiments if the gas characteristics can contribute under some conditions a better system performance.
  • Yet another embodiment of the invention uses heated air or gas as a means to assist in overcoming the adhesion force of particles within the OUI so that they may become entrained in the air streams.
  • jets are basically just holes in the wall and blow the air directly at anything that happens to be in its sights. Variations of this concept include a simple hole for the flow of whatever gas or liquid is being used, blowing this material at some angle to the surface. This can be accomplished either by re-orienting the OUI so that the impact does not occur at right angles to the surface, or by re-orienting the direction of the jet by any of several means.
  • These jets remove particles by direct momentum exchange and, in the near field of the impact area, by aerodynamic shear forces.
  • the jet has an opening which is not circular; otherwise it is an extension of the classical circular hole jet, to accomplish several things.
  • Another possibility is that one might wish to set up self sustained aerodynamic phenomena such as pressure pulsing (whistling), boundary layer breakdown and recovery, and so forth.
  • Yet another is to arrange for the flow to exit the hole in a tangential manner to the surface rather than normal to it. This could be used, for example to provide a bath of air over the surface. Further, if such flow exiting the hole were swirling, such a flow could be used to induce other vortical flows.
  • This type of jet is also called an air amplifier.
  • a small high speed flow of air is directed over the smallest area on the inside of a ring, and a fantastic amount of surrounding air is induced to flow through the ring.
  • Volume flow rate amplification factors of 40 have been observed (see, for example, Exair Corporation, Catalog No. 20, for several air amplifiers whose amplification ratio is 25).
  • such jets may be used near a wall, where the flow into the device would be at right angles to the outflow.
  • shock wave jets may be used. Such jets may produce "normal” shock waves and/or “oblique” shock waves, which have the added advantage of also being accompanied by oblique "expansion” waves of the same strength.
  • This type of jetting is created by using over- or under-expanded supersonic jets and is particularly effective at stripping particles from a surface.
  • Fig. 23 shows a pressure vs. time profile of one embodiment of a particle extraction cycle.
  • jetting cycles there is initially a set of jetting cycles, in this case 4, with an initial rapid pressurization from an atmospheric or sub-atmospheric base pressure to a peak pressure, and then a slower depressurization, reaching a pressure level somewhat above baseline before the next jet cycle.
  • the jetting cycles serve the dual purpose of inducing a mechanical impulse to detach particles from surfaces and tends to distribute the particles inside an object under inspection throughout their void volume.
  • a second phase of "breathing” is then applied after the chamber pressure reaches base pressure, wherein a more symmetric pressurization/depressurization cycle is employed, generally through the same jets, but operated intermittently to prolong the time between initialization of pressurization, and peak.
  • a more symmetric pressurization/depressurization cycle is employed, generally through the same jets, but operated intermittently to prolong the time between initialization of pressurization, and peak.
  • different jets or inlet gas ports may be employed in this phase.
  • the peak pressure during the breathing cycle may be higher than the peak pressure during the jetting cycle, and is generally allowed to decay to baseline. In this case, 3 breathing cycles are shown.
  • the breathing cycles serve the principal purpose of transporting or equalizing a particle concentration within an object under inspection and the void space outside the object, so that the particles may be collected.
  • the breathing cycle typically also includes proper control over gas flow dynamics within the chamber to avoid settling of particles on the inner surfaces of the chamber, and to resuspend particles that may have settled.
  • a bulk flow of gas is provided toward the vacuum port to induce a transport of these particles as well.
  • a final puff is shown, which may assist in clearing particles suspended in the chamber into the vacuum port, without necessarily inducing efflux of additional particles from the object under inspection.
  • Jets used for Breathing Virtually any jet which allows air into the chamber can be used for the pressurization part of the breathing. As the chamber pressure rises, air enters the OUI. Preferably, the surface impacting jets are used for pressurization.
  • Impact jets seek to cover as much of the surface as possible, and to provide as much impact momentum to the surfaces of the bag as possible.
  • the normal shock wave jets and the Coanda jets are quite useful.
  • the trajectory of particles within the chamber after they have been removed from the bag is an important aspect in the efficiency of the system.
  • the walls are bathed in a layer of air, which is moving toward the exhaust port.
  • a second type of jet places a stream of air along the ceiling and walls so that all chamber surfaces have a layer of air moving toward the exhaust port, wherever it is. Typically, this port is at the center of the floor.
  • other embodiments include other locations as well as a plurality of exhaust ports.
  • the ceiling fans may be oriented in such a way as to create a flow toward the center of the ceiling and down the walls.
  • the flow toward the center would then be used to bathe the OUI so that its exterior surface would likewise be swept of particles trying to land on it instead of the walls.
  • a further embodiment relies on the instability of an inward flow to a point, and the tendency to do so in a swirling manner.
  • the swirl can then be used to create a "cyclone" inside the chamber which induces the particles to flow outward and be entrained into the wall flow.
  • Aerosols and gases lighter than air such as amine groups
  • aerosols and gases are induced into the vacuum system.
  • the chamber volume may be swept clean of particles in a manner similar to methods used in "clean room" environments.
  • the ceiling is perforated to allow air to be sucked in to the chamber by vacuum system floor ports (of course, if the ports were elsewhere, a corresponding alternative for the location of the perforated wall would be used). This allows the entering air to completely replace the air being drained by the vacuum system through the exhaust port(s) so that the particles would correspondingly be removed with this air. 5.
  • Particle collection Airflow is provided which direct gas streams with entrained particles, to accumulate at the desired location, typically a filter, to collect the particles.
  • Adequate particle collection is significant to the system as a link in the chain of particle extraction to particle detection since it determines which fraction of the extracted particles are getting to the detector; the higher is the number of particles collected, the better is the performance of the system.
  • Particle collection is analogous to a lens focusing a light beam. Particles spread in a large area are directed to a small area that can be detected.
  • the particle collection unit consists of the exhaust ports and conduit which transports the particles to a collection surface or past a collection/viewing site or directly into a particle analysis device.
  • the collection surface in the present preferred embodiment is a porous filter which, after collection, is placed in a particle analysis device. Special care is taken to ensure that particles are not lost to the walls of the conduit.
  • smooth bore passages are used, specifically avoiding any geometric irregularities or discontinuities which can cause flow recirculation or vortices which greatly increase wall collision frequency.
  • irregularities in hoses, at connectors or junctions, and the like lead to particulate deposition and contamination, and reduced transport of particles to a detection location during a cycle. Therefore, in a preferred embodiment, the pathway between the chamber and the detection location has smooth, junction-free walls, without substantial discontinuities that might lead to unintended particle deposition.
  • particles are ionized, directly or indirectly, e.g., upon entering the exhaust port(s) and electric fields thereafter direct particles to the detection surface or region.
  • Particles are typically distributed across the entire air stream cross section.
  • some collection systems according to the present invention only a fraction of this air passes through a filter, hence the particle collection area is smaller than the airflow cross section.
  • the particle collection area is smaller than the airflow cross section.
  • only a portion of the extracted particles land on the filter surface area used for detection.
  • the particles are collected on a standard "swipe", i.e., a porous, non- woven fibrous material.
  • the swipe is that can be detached from the system and disposed into the particle detector.
  • a fiberglass filter or other type of filter may be employed.
  • the effectiveness of particle collection on a standard type swipe can be increased via changes to swipe geometry consisting of: cones, multiple cones, a plurality of swipes, a plurality of cones, a labyrinth of swipes, multi mesh size swipes, positioning the swipes at varying angles, changing the angles dynamically, or via changes to swipe material.
  • Non-standard swipe or other filter size and geometry can also enhance the effectiveness of particle collection. Having swipe material filters of varying sizes and areas, tube shaped swipes, cone shaped, spiral shaped, with holes and mini cones, supported by a wire mesh for shape reinforcement.
  • Non-standard large swabs may be used with a Tunable diode Laser (TDL) or Laser Detection
  • LDS LDS System for particle detection.
  • This can be implemented by inserting large swabs or filter material or sticky material into the collection location of the system, or exhaust tubing, in a strip form.
  • part of the membrane, or exhaust tubing with can be replaced with a disposable or consumable part which can be detected with TDL or LDS detectors rather than with an IMS detector.
  • a particular advantage of swipe material is its low cost, uniformity, and general freedom from contamination. Since the filter can be a significant disposable cost, the qualification and use of an inexpensive filter advantageously reduces operation cost of the system.
  • Focusing the particles onto the area used for detection is useful for good system performance, as without particle focusing, either the filter is unduly large, leading to increased operating costs and greater difficulty in volatilizing the sample for the IMS detector.
  • a full flow-path width filter can result in increased back pressures, and reduced peak flow rates in the system, which may result in particulate settling on chamber or conduit surfaces, and possible reduced particle extraction efficiency from the OUI.
  • the filter is disposed over only a portion of the airflow path, the majority of the particles may be lost in a bypass stream.
  • Particle concentration in a portion of the stream (focusing) may be implemented by using various techniques utilizing aerodynamic, acoustic, thermophoretic, acoustophoretic, and/or electrostatic techniques.
  • the detector may be designed to selectively volatilize particles from the concentration region on the filter, thus maintaining a high concentration of vapors in the sample stream.
  • a narrow cavity outside the outer diameter of the filter creates a bypass to the flowing air stream.
  • the bypass can be made to create a Venturi effect, meaning that the airflow through the narrowing gap decreases pressure on the back side of the filter, resulting an increase of pressure differential between the front and back surfaces of the filter and thereby increasing flow through the filter.
  • the Venturi bypass has been found to substantially increases the number of particles disposed onto the filter by increasing the amount of mass flow through the filter as compared to a non- Venturi bypass flow embodiment. See, US Provisional Patent Application No. US60/778,370, expressly incorporated herein by reference.
  • the effect of pressure increase across the filter may be accomplished in another embodiment by providing a separate, higher vacuum to the back of the filter than to the bypass.
  • FIG. 12A and 12B illustrate an aerodynamic particle concentration embodiment employing a clean air outer flow 61 combined with a particle laden inner flow 62 creating the concentrated particle flow 63.
  • Fig. 8 A depicts an option wherein the clean air outer flow 61 is joining the inner flow 62, by flowing in parallel, while Fig.
  • a centrifugal force may be used to concentrate the particles in the stream onto a narrow ring bordering the external diameter of the air flow cross section pipe or imaginary pipe.
  • the detector area has to be included in an annular ring area compatible with the particle concentration ring.
  • the filter may be cylindrical, disposed at the end of the centrifugal pipe, wherein a portion of the gas which is concentrated with particles flows radially through the filter, and a relatively depleted portion flows axially through the tube.
  • the centrifugal force may be combined with a conical shape filter to focus the particles onto a central area, substantially smaller than the cross section of the laden particle stream flow.
  • Fig. 13 illustrates the centrifugal particle focusing technique.
  • a vortex motion created by swirling flow forces 68 exerts centrifugal force on the particles 69 flowing with the air stream. The exerted centrifugal force pushes the particles 69 outward from the center.
  • a conical shaped filter 71 concentrates the particles 69 flowing in the air to a substantially smaller cross section area, compatible with the particle filter 71 area.
  • the annular ring is just one example of non-circular filter shape. Many different cross sectional areas of high-density particles concentration can be utilized by the matching shape of the filter.
  • thermophoretic filter may be used for focusing the particles onto the area of the filter that is substantially smaller than the cross section of the of the airflow tube.
  • Fig. 14 illustrates the Thermophoretic filter.
  • the thermophoretic filter is very similar to the centrifugal filter except that heating is used rather than centrifugal force, for exerting an outward force on the particles.
  • a high temperature wire 70 at the center of the air stream is used for heating the particles 69 and creating a force that drives the particles 69 away from the centerline towards the pipe wall and up the stream tube passing the particles through the conical shaped filter 71 at the outlet.
  • the pipe walls may be heated rather than the centerline of the pipe, causing particles to be driven towards the central area of the pipe.
  • the conical shaped filter 71 is not required in this case.
  • a standing acoustic wave may be used for concentrating particles in a defined small area of the air pipe cross section.
  • a standing acoustic wave perpendicular to the airflow creates a variable field of air pressure transversely to the airflow. Particles tend to concentrate at the lowest pressure areas of the pipe cross section.
  • Fig. 15 illustrates an embodiment of the particle collection unit created by a standing acoustic wave particle concentrator.
  • An acoustical wave transducer 73 generates a standing acoustic wave, preferably with the cylindrical shape of the air stream pipe. Two perpendicular synchronized pairs of acoustical wave transducers 73 may attain the cylindrical shaped pressure field.
  • Fig. 16 illustrates the waveform of the standing acoustical waveform generated by one the acoustical wave transducers.
  • the vertical axis of the waveform is the air pressure function generated by the transducer 73 while the horizontal axis is the distance crosswise the pipe cross-section diameter.
  • the second acoustical transducer perpendicular to the first one (not shown in Fig. 15), jointly operates with the first transducer to create the desired pressure field.
  • an electric field may be used to focus the particles onto the filter surface.
  • a gas flow, and/or the particles themselves, may be charged.
  • a high voltage or energetic (ionizing) photons are applied.
  • the particles can be ionized directly by a radioactive source (such as Polonium or Americium), or by other known effect.
  • a radioactive source such as Polonium or Americium
  • the ions produced collide with the suspended particles, conferring on them an electric charge.
  • the charged particles, (by direct or indirect effect) are electrostatically steered to a desired location or configuration, for example by passing through two orthogonal pairs of parallel high voltage plates.
  • Fig. 17 illustrates the electrostatic particle concentration embodiment of the particle collection unit.
  • the air stream 77 passes through a Gas Ionizer 76 comprising multiple high voltage metal plates and used as an apparatus for charging the gas molecules with appositive charge.
  • the collisions between gas ions and the particles transfer the charge to the particles 69.
  • the charged particles pass through the two orthogonal charged particle deflection plates 75, and are deflected to form a narrow beam of particles.
  • the particles in the narrow beam pass through a porous screen 78, to discharge the particles 69 prior to being disposed on the particle filter 74 for detection.
  • the filter 74 itself is charged oppositely to the particles, and the particles are attracted directly to the filter 74. In that case, the particles 69 need not be discharged, and the electrostatic forces help hold the particles to the filter 74.
  • the filter 74 may be charged electronically, or tribo-electrically.
  • a commercially available pre- concentrator apparatus may be used for concentrating the particle beam and further entering the beam into an integrated detector for on line particle detection.
  • Fig. 18 illustrates an embodiment of the particle collection unit using the preconcentrator 82.
  • the preconcentrator 82 is a device acting as a molecular filter.
  • the inlet airflow 81 is substantially larger than the airflow entering the IMS detector 85.
  • the inlet airflow 81 is pulled through a material known as metal felt, a high-density mesh of metal filaments. The metal felt allows only air to pass to the exhaust line while trapping through absorption high molecular weight organic molecules such as explosives.
  • valves are closed to isolate the preconcentrator 82 from the ducts of the inlet 81 and exhaust 83 airflows.
  • the metal felt is heated to a temperature which desorbs any collected explosive material into a vapor phase, within a small desorb airflow 84 volume directed into the IMS detector 85.
  • the inlet airflow 81 and Desorb Airflow 84 are preferably perpendicular to each other. The net result is a high concentration of particle vapors reaching the detector 85 and the added benefit of the detector 85 being integrated with the system rather than using a filter that has to be disposed into the particle detector.
  • Vortical airflow a three-dimensional swirling airflow causing particles to move in a preferred direction, is another technique used for particle collection.
  • Non-aerodynamic techniques can be also used to aim the particles in a desired direction.
  • An electric field can be used to direct and focus a stream of particles by charging the particles with some form of ionizer.
  • a magnetic field can be used in a similar way for polar particles such as plastic explosives. Gravitational forces may be also used for particle collection.
  • Acoustic waves may also be used as a means for directing particles. Any combination of the above particle collection techniques can be applied to the system in any given embodiment.
  • one embodiment of the invention employs a disposable, readily interchangeable transport conduit, which for example, may integrate a filter element for concentrating particulates. Gas leaving the chamber enters the transport element, which integrates suitable air flow and/or aerodynamic elements and leads directly to a filter.
  • the transport elements may, for example, be formed as a tube or conic section which abuts the bottom of the chamber, and connects to a vacuum port subsequent to the filter element.
  • Particle detection Current technology for detecting small traces of particles is highly developed. A bulk of material packaged or carried in a baggage releases a number of microscopic particles to the surroundings. Analytical devices are available for detecting trace particles weighing as little as 1 nanogram.
  • Optical detection techniques based on the Raman scattering principle have even higher sensitivity of particle detection.
  • the availability of these sensitive particle detection technologies combined with the capability of the system to extract and transport the particles from the OUI onto the detector, are important to the performance of the system.
  • IMS Ion Mobility Spectrometer
  • IMS Ion Mobility Spectrometer
  • the IMS device functions as an ion-selective filter, which measures how fast a given ion moves in a uniform electric field gradient through a given atmosphere.
  • the molecules of the sample are ionized by any various ionization methods.
  • a sample of the ions is let into a drift chamber and subjected to a strong electric field accelerating the particles toward the detector.
  • the ions get separated by their mobility and arrive at the detector plate in order of their velocity, generating a response signal characteristic for the chemical composition of the measured sample.
  • An improved version of the IMS detection method uses the Ion Trap Mobility Spectrometry (ITMS) technology allowing detection of different particle materials simultaneously.
  • IMS Ion Trap Mobility Spectrometry
  • Raman spectrometry technique is used to study vibrational, rotational and other frequency modes of molecules and crystals by illuminating a sample with a laser beam. It relies on Raman scattering of laser light, resulting in the energy of the laser photons being shifted up or down in spectrum. The shift in energy gives information about the phonon modes in the system.
  • Enhanced Raman Spectrometry is a very sensitive version of Raman Spectrometry.
  • a silver gold roughened surface substrate is used to absorb the chemical particles.
  • the detected chemical absorbed in the substrate is re-perturbed leading to enhanced spectral features and detection sensitivity.
  • Another optical technique is the LDS method using laser fluorescence for remote sensing.
  • TDL or LDS detectors may be incorporated into the system for in- situ analysis of traces from the external and internal portions of the article being inspected.
  • a laser based detection system can be placed such that the laser beam or a curtain is aimed at portions of an OUI cavity, or internal portions of the exhaust conduit.
  • the laser can be used to scan the filter, or its mount, and/or surrounding in continuous or pulsed fashion. Such a system could replace the filter, allowing for simple airflow and improvements in system cleanliness.
  • traces can be identified by an in-situ detection process, saving analysis and operational time and eliminating operator related errors.
  • the TDL or LDS can also be used to verify system cleanliness by doing a fast sweep of a laser curtain over the complete or portions of the OUI cavity (chamber) and exhaust conduit.
  • the filter can be designed as a labyrinth, where the laser is positioned in areas where the flow is slower, in order to increase "hit rate" of the laser of the traces.
  • In situ laser detection may be implemented through various schemes, including: 1.
  • the laser beam detects traces while they are on surfaces, or suspended in the air, e.g., in a laminar flow pattern or in a turbulent flow regime, while being extracted or transported from one location to another.
  • the laser beam varies diameter, or curtain, where the width of the beam is larger then its thickness. This curtain may also be generated by rapidly scanning the laser across the flow path.
  • the tube being straight, or with varying degree bends, or designed like a coil with at least one turn, when airflow is significant. This allows the laser path to be generally axial with the tube.
  • particle detectors can be selected for any embodiment of the system. Multiple non-destructive sampling operations may be used in conjunction with each other, though only a single destructive sampling technique unless the technique operates on only a portion of the sample. Regardless of the detection technology used, particle detectors may be detached from or integrated with the extraction system.
  • the collected particles are accumulated on a filter disposed at the outlet of the chamber.
  • a stationary or moving sticky tape may be disposed inside the chamber at a location where particles are collected.
  • the sample of particles can be placed directly with the sticky tape or the filter onto the detector or a swab can be used to transfer the accumulated particles onto the detector substrate.
  • the particle detector can be integrated with the sealed chamber by way of having the particle detector disposed within the exhaust port.
  • An opening in the chamber wall allows particles to move from the chamber onto the particle detector.
  • Fig. 8 illustrates a block diagram of an integrated extraction chamber 2 and particle detector system 41.
  • the opening of the particle detector 41 is attached to the exhaust port of the inspection chamber 2 through a suction valve 43.
  • the detector comprises an optical SERS detector 46.
  • a silver gold substrate 44, used by the SERS particle detector 46 is placed inside the extraction chamber 2 at a particle collection area, while the rest of the detector 46 is generally placed outside the chamber 2. Particles landing on the substrate 44 are detected through a window 45 in the chamber 2 wall.
  • the particle substrate 44 is disposed in the inspection chamber 2 at the particle collection area near the exhaust (suction) port 43.
  • a window 45 disposed on one wall of the chamber 2 is used to pass an optical detection beam transmitted by the laser, onto the particle detector substrate 44 inside the chamber 2, which is then reflected from the substrate 44.
  • the system is considered an integrated system by the fact that particles from the chamber enter the particle detector directly and there is no requirement for manual intervention to transport the particles from the collection area in the chamber into the detector.
  • a system that makes use of the LDS laser fluorescence detection method does not require collection of particles inside the chamber.
  • the particle detector can scan the volume of the chamber and detect particles floating in the volume of the chamber.
  • the particles can also be allowed to settle on a surface, in which case only the surface, and not the full volume, need be scanned.
  • the chamber Since the system is highly sensitive to minute traces of particles, the chamber has to be cleaned thoroughly after each cycle of inspection from any residual particles of the current inspection cycle, to prevent erroneous detection in the subsequent cycle. This is especially important if the environment becomes, or possibly becomes, contaminated with detectable particles, leading to a large number of true positive readings. In order to permit screening to continue, the system must be reset to a known good state after each screening, so that the extent and nature of the problem can be known, and each positive reading followed up appropriately, rather than a degree of complacency imposed, as would be the case in the event that true and false positives cannot be distinguished. Likewise, loss of particles on the chamber and conduit walls decreases detection sensitivity.
  • a thorough cleaning procedure is specifically required after a positive detection has been made.
  • a variety of techniques can be used for cleaning.
  • the techniques consist of manual or automatic wiping of the chamber inside walls, using jets that sweep the floor and inside walls, and coating the inner surfaces of the chamber with non sticky and slippery material to prevent contamination.
  • Further cleaning techniques involve immersion techniques, such as flowing liquids through the chamber and contaminated vacuum lines.
  • Ultrasonic transducers may be used to generate surface waves which reduce the forces necessary to dislodge particles from the walls.
  • Cool-Hilsch effect to cause heated air to be separated from cooled air by supplying only compressed air. This allows for the air entering the circular recessed jets to be heated, which may be desirable.
  • the cold air out of such a device can be used to supply a set of the corner fan jets on the floor of the chamber. Variations may include using some of the cold air output to cool the compressor, which can get quite warm.
  • One way to efficiently change a chamber configuration is to provide a "pop up" jet orifice head and/or turbulator, which in a first phase, is flush with the surface, or having an extraction function, and in a second phase is raised from the surface, and generating a disruption in and/or parallel gas flow across the surface, to prevent particles from lodging at the surface.
  • a flow pattern from a "pop up” jet includes highly energetic vortical flows on the surface to scrub and to dislodge particles.
  • the "pop up" function is advantageously initiated by a change in pressure, typically from the same gas source as used to expel air from the jets.
  • a simple chamber and counter-balance spring permits a rapid return of the head or turbulator to a relaxed position after pressure relief.
  • a pop up head allows a jet to be directed parallel to the surface during a raised phase, while non- interfering with gas flows along the surface when retracted.
  • the impulse generated by pressurization or depressurization of a head or turbulator also produces vibrations which may dislodge particles. Jets may also be provided to direct gas flow normal to the walls, to provide sufficient force to move particles adhered thereto.
  • the transport system also is subject to a cleaning phase.
  • the transport system is typically configured as a cylindrical tube.
  • the cross section of the tube may be varied, for example by flexing, which will lead to an ovalization, and a resulting inner and outer surface.
  • the tube may also have a side port which leads to a spiral flow along the wall.
  • a wad (bolus) may also be presented at one end of the tube, and blown to the other, wiping the walls of the tube in the process.
  • a bypass may be provided to remove the wad from the flow path.
  • a snake or rod may be used to clean the conduit.
  • a liquid cleaning cycle may also be used, preferably followed by a warm air drying cycle.
  • Passive measures include using appropriate materials and configurations for the construction of the exposed surfaces.
  • the use of non-stick materials such as Teflon or similar material has been found to greatly assist in reducing the level of accumulated contaminants and aids in cleaning.
  • using smooth finishes in all exposed areas avoids gaps or cracks for contaminants to enter. This is particularly true in flow passages where the use of smooth bore tubing and fittings without discontinuity is critical.
  • the geometry itself may be designed in such a way as to couple with the flows to create contamination prevention cycles. This could be, for example, the use of special curves in the tubing or special contouring in the chamber.
  • Active measures to prevent contamination include the use of specially contoured surfaces to interact with the flows, which prevent contamination to reach the exposed surfaces.
  • Heating, cooling, acoustic sources, various aerodynamic phenomena such as turbulence, organized vortices, shock waves, unsteady flows, pulsing flows, and the like may all be used to prevent particles of contamination from reaching the walls and other exposed surfaces.
  • a thorough cleaning procedure is specifically required after a positive detection.
  • a variety of techniques can be used for cleaning. The techniques range from manual wiping of the chamber inside walls, to using jets that are sweeping the floor and inside walls, coating the inner surfaces of the chamber with non-sticky and slippery material to prevent contamination. More cleaning techniques involve immersion techniques such as flowing liquids through the chamber and contaminated vacuum lines. Tests were completed comparing particle deposition both with and without heating of the conduit walls. The intent was to see whether heating would decrease the accumulation rate of the particles on the wall. In fact the opposite occurred. It was found that, while heating may have diminished the collision rate of particles with the wall, the heating also significantly increased the wall stickiness of the plastic tubing used in the test, apparently more than diminishing the collision rate.
  • a non-thermally reactive tube wall is preferably used; for example, Teflon coated, or and metal tubing is preferred.
  • Teflon coated, or and metal tubing is preferred.
  • a secondary observation was that the particles which did accumulate, did so seemingly only at places where geometric imperfections caused the flow to depart from smooth. Such places include gaps between the hose and the fitting, bumps caused by the fitting (o- rings and crimp rings), and at small curvature radii in the somewhat non-circular tubing. Therefore, using smooth bore tubing and fittings will likely result in at least an order of magnitude decrease in wall deposition.
  • we can deliberately place bumps where we wish to do so. Heating can thus have multiple effects, including reducing contamination, increasing particle vapor pressure, and increasing particle adhesion to some surfaces, and therefore can be used in various aspects of the design with various results.
  • the system is operated in an empty state, in order to assess the possible presence of contamination in the chamber. Since an OUI is not present, the process seeks to dislodge any particles adherent to surfaces of the chamber and conduit(s), and possible suspended particles in the chamber. Therefore, the jets are preferably operated in a cycle which provides maximum surface effects, but generally without jets intended principally to dislodge particles from an OUI. This cycle is distinguished from a cleaning cycle in that in the verification cycle, the exhaust air is directed to a detection device, and this the air volumes and flow rates are limited by the particle concentrator system characteristics.
  • an optical scanner is disposed to scan a surface of the chamber, to verify that there are no traces which would generate a positive reading, and thus potentially interfere with t subsequent screening operation.
  • the functional units comprising the system, discussed in the preceding sections, operate closely and collectively over time to carry out the extraction, transport, and detection tasks. Various modes of operation can be implemented to reach optimum performance for given operational conditions.
  • System automation is a key aspect of embodiment of the invention. The use of industrial controllers, or other automation technology, for operating the pneumatic system is preferred, since they offer an expedient way of jet operation as a function of time. However, automation is not only limited to jet operation.
  • the system cycle comprises particle extraction, particle transporting and chamber cleaning.
  • Fig. 10 illustrates the operation of an embodiment of the invention as a function of time.
  • the object is placed in the chamber, and the chamber lid sealed closed.
  • a maximum chamber pressure of 7 psig, and a chamber size of 20 inches by 17 inches an approximate force on the cover is about 2,000 lbs, so the cover must be securely clamped shut.
  • the extraction cycle starts with particle extraction, wherein air jets are operated to extract particles from within the OUI, and release particles adhering to the exterior surface of the OUI.
  • particle transport begins, with the same or different jets operating to keep particles afloat in the chamber volume, and to transport the particles with the jet streams to a particle collection area.
  • a chamber cleaning process begins, typically using a special jet, and/or other cleaning techniques discussed above.
  • the shown cycle time is the overall time to complete an inspection cycle.
  • a filter or substrate which collects the trace of particles is manually removed from the chamber and disposed in the particle detector, or automatically displaced to a detection position, or detected in situ.
  • jets blow to release particles sticking to the inside walls of the chamber, thus maintaining extraction efficiency and reducing contamination of the chamber.
  • Particle extraction and particle transport are generally not distinctive operations of the chamber. Particle transport has to start before particle extracting ends, to transport particles that are already out of the OUI. Thus, the jet operation is shared between particle extraction and particle transport by cycling several times, which can enhance the performance of the system.
  • a system embodiment utilizing time division mode of operation is depicted in Fig. 11. The system cycles repeatedly between particle extraction and particle transport steps rather executing each step distinctively. The total particle extraction time and transport time are derived by the addition of the individual cycle times. Shortly after particle extraction begins, particle transport begins, so that it is likely that fewer particles get lost inside the chamber. Following the time division operation, chamber cleaning is implemented. The number of cycles used in the time division mode, can be determined in a manner to optimize the performance for given operational conditions and system requirements.
  • the various jets may be operated in a scanning mode. Jet scanning can be used to implement the operation in a way that leads to a better performance of the system by extracting more particles from the OUI, having fewer particles stick to the chamber surfaces and directing more particles to the collection area. Thus, various regions within the chamber may be in different phases (extraction dominating, transport dominating) simultaneously. Any combination of jet operation in time can be applied for best performance.
  • Various automation levels can be applied to the system operation. The lowest level is the automatic control of the pneumatic system including the jet valves and the vacuum valves. A second level of automation can be applied by integrating the particle detector with the chamber so that extracted particles reach the detector directly without manual intervention.
  • a third level of automation may be applied to the chamber cleaning operation by implementing the cleaning without any requirement for manually wiping surfaces inside the chamber.
  • a fourth level of automation may be implemented by placing a video camera outside the chamber and imaging the inside of the chamber through a window.
  • the camera may include a video monitor and image processing electronics.
  • the OUI position may be controlled automatically based on image data processing.
  • the highest automation level may include any combination of the above mentioned automation levels with the addition of automatic handling of the OUI into the chamber and out of the chamber, meaning that system operation from beginning to end is fully automated. 9. Tray
  • One embodiment of the automated system may include a tray (net) unit movable by a conveyor used to transport the inspected article, placed in the tray, into and out of the inspection chamber and out of the inspection chamber.
  • a tray (net) unit movable by a conveyor used to transport the inspected article, placed in the tray, into and out of the inspection chamber and out of the inspection chamber.
  • the trays or net may be use for the following tasks: 1. Handling of the articles form the conveyer into and out of the vessel.
  • the tray may be made of a variety of materials and come in different shapes.
  • the structure of the tray may be shaped like an open box with bottom, side and top walls.
  • the structure of the tray may be a tubular frame, rigid in part, of metal or plastic, or hollow tubes, pneumatically inflatable, or a combination of the above.
  • the tray may come in different sizes to accommodate varying article sizes.
  • the tray may include different mesh size and tubing, a combination of mesh sizes and enclaves for various articles.
  • the tray may also be of a modular design, similar to Lego® type parts, which can quickly assembled to best address the characteristics of the article being inspected.
  • the tray may consist of incorporated pneumatic, Piezo-, electric or other actuators or incorporated with sensors, grasping locations, handles, inserts, hooks for a conveyer or a manipulator or a robot.
  • the tray may have humidity, particulate, and/or electrostatic charge sensors to determine a humidity, particulate emissions, and charge of the OUI, and if these are outside of normal operating parameters, to generate an alarm and/or prevent the OUI from entering the chamber.
  • a system for remediating out of range conditions may be employed, such as antistatic treatments, humidifying or dehumidifying treatments, particulate scavenging, etc.
  • Luggage may also be encoded and tagged, for example with a radio-frequency identification tag (preferably cryptographically authenticated), which can be read by the tray or reader in the environment, which, for example, can be used to establish extraction parameters and to verify that the luggage or OUI is compatible with an automated screening process.
  • the system may also verify that luggage or other OUI are indeed compatible.
  • the luggage so tagged or encoded may be of a special type designed to more easily allow extraction of particles from the interior. This can be done by having specific ports, for example to allow a special air hose to be connected and thence provide an interior air flow which more advantageously extracts particles. Such luggage so sensed as being of this type, could be subjected to a shorter process time thus decreasing the owner wait time.
  • the gas injected in the bag may have a tracer, such as a particulate, to provide a positive control for release of particles from within the bag.
  • a detector for clothing fibers or other normal particulates from airline carry-on baggage may be implemented, since under normal circumstances the extraction process would release such particles.
  • radiographic evidence of the contents of the bag is obtained, i.e., a recorded image from an X-ray screening device, to confirm that the normal particle extraction components are not tampered with.
  • the encoding of the bag may include not only the type of bag, but other information.
  • a writable smart tag may include a travel and screening history of the bag.
  • This tag may further identify the owner, and serve to deter theft and assist in recovery, as well as possible tracking through an airport or the like.
  • the smart tag is described herein as being applied to particle extraction and analysis systems, such a smart tag may also be employed with other systems within a security infrastructure, and indeed, the luggage and tag are preferably designed to facilitate all relevant inspection and screening. While such a security implementation is preferably optional, in some cases it may be mandatory; that is, only approved and encoded items are permitted in secure areas, wherein the approved items conform to efficient security screening procedures and other restraints, such as size and weight.
  • the tray may consist of pneumatic or heating assemblies connected to the external pneumatic system and heating elements through a quick connecting mechanism.
  • the tray structure may be dynamically reshaped, rather than rigid, to permit ready adaptation to the size and shape of the inspected article. Collapsing walls, multiple section folding, and an additional cover can also realize dynamic reshaping. Dynamic reshaping can be further realized by a rigid structure changing during the cycle, e.g. the bottom of the tray can collapse or reduce rigidity once in the vessel, to better encompass the OUI. Rigidity change can be accomplished by inserting flexible portions to the frame (rubber) and designing the tray frame to use available mechanical support (e.g. conveyer) and to change the shape when the mechanical support is removed.
  • a rigid structure changing during the cycle e.g. the bottom of the tray can collapse or reduce rigidity once in the vessel, to better encompass the OUI.
  • Rigidity change can be accomplished by inserting flexible portions to the frame (rubber) and designing the tray frame to use available mechanical support (e.g. conveyer) and to change the shape when the mechanical support is removed.
  • the tray may exert agitation on the carried article intended to extract particles from the OUI.
  • the agitation can be applied by a cam shaped device or by driven components of the tubular frame. Hollow tubular components of the frame that can be inflated and deflated to agitate the article, may be used for agitation.
  • An attached accelerometer could sense the response motion of the OUI and hence deduce characteristics such as mass and/or freedom of movement of objects within the bag.
  • the tray can be cleaned by the operator, as part of the standard operation of the machine either in a single or batch mode, in the vicinity of the system or far away from the system. Cleaning of the tray may be accomplished by wiping, with a gas flow (preferably heated), vapor submersion, wet cleaning and drying, and agitation.
  • the tray or a portion thereof may be made of disposable material, such as cellulose materials or recyclable plastic, or steel wire, for example.
  • the trays can be made or assembled (e.g., unfolded, connected) automatically, prior to use or as a part of a reuse system.
  • the tray may serve as part of the filter, collecting residues, particulates or vapors from the article being tested.
  • the tray can be automatically circulated using a conveyor from the output port of the system of the machine to the import side.
  • the re-circulation process can be done in while the trays are horizontal (large area facing top or down), or vertical (large area facing side ways).
  • the circulation can be performed around the machine, or from the top or below, in an escalator method.
  • an automated cleaning cycle is implemented, to ensure that the trays are decontaminated prior to reuse.
  • contamination is not limited to the particles being sought, a UV light or other biological decontamination is employed. Other decontamination techniques may also be employed.
  • the conveyor may also be used to agitate the OUI prior to the trace extraction process.
  • the OUI may be heated on a conveyor system, for example in a tunnel, prior to the trace extraction process.
  • a mechanical vibrating mechanism or a heating system may be used for releasing particles adhering to the exterior walls of the object.
  • Temperature sensors, pressure sensor, a video camera and other sensors may upgrade the intelligent tray even further. Tray functioning has to include a cleaning procedure following the article inspection to be available for placing the next article for inspection. Sensors in the conveyer system may be used to sense and record weight and size of article, for adaptive processing and other purposes.
  • the chamber is designed to have a plurality of jets, which are selectively employed in dependence on characteristics of the OUI, which may be determined manually or automatically.
  • characteristics of the OUI which may be determined manually or automatically.
  • an excess of jet orifices is provided on the chamber, not all of which are used during any given cycle.
  • the jets are typically arranged in clusters, adapted to provide extraction of particles from common OUI types.
  • These clusters may be arranged, for example, concentrically on the top, bottom and sides of the chamber, to treat small, oblong, and large objects, respectively.
  • the jets have a generic entry portion leading to the chamber, and a modular customization portion at the orifice, to thereby modify the jet pattern of an array of ports.
  • the modular customization portion may be manually selected or automatically changed.
  • the pattern of orifices may be predetermined based on an OUI type or intelligently modified based on an analysis of the particular OUI, and not necessarily limited to a narrow range of types. For example, an analysis of zipper, pocket and aperture locations on a bag may lead to a selection of optimal jet types directed toward those locations. Since the operation of the system is typically limited in a volume of gas used for any extraction operation, both to conserve compressed gas, and also to avoid overwhelming the particle concentration and/or analysis units, jet locations which serve little purpose or reduce efficiency are blocked or have limited gas flow.
  • the components within the chamber may be subject to contamination, and it is important that in case of contamination, or as a part of a regular maintenance cycle, that such parts be cleanable or replaceable. Therefore, it is an aspect of the invention to provide a disposable modular customization portion element, for example formed of molded plastic, which may be readily replaced when worn, contaminated, or reaches an end of its design lifetime.
  • a disposable modular customization portion element for example formed of molded plastic, which may be readily replaced when worn, contaminated, or reaches an end of its design lifetime.
  • an operator selects a customization element suitable for that OUI, and thereafter disposes of the modular customization portion element.
  • an inexpensive design may be provided, for example of thermoplastic or thin metal sheet, that is customized immediately prior to use for a single inspection, and thereafter disposed of or sent for recycling.
  • a positioning and orientation mechanism added to the tray may be used to place the OUI in a preferred location and orientation for a further efficient particle extraction, collection and detection.
  • the positioning and orientation may include any selected XYZ position in the chamber volume and any rotational angular position around the XYZ coordinate system.
  • the system may be integrated within a full airport security infrastructure, alongside other inspection systems.
  • An efficient airport security system may require combining the individual inspection units into an integrated airport security system through digital data transfer between the individual units.
  • the system according to the present invention may therefore comprise a transceiver activated by a standard interface capable of reading incoming data from the other inspection systems and outputting data to the other inspection systems trough a communication link connecting all the units of the security system.
  • a communication link may be a traditional 10/100/1000 BaseT wired Ethernet system or other 802.11 compatible system, a mesh network (Zigbee), WiMax (802.16), or other known networking technology.
  • Fig. 19 illustrates an airport security integrated system.
  • the integrated security system may include but not limited to, an X-ray inspection system 92, an explosive detection system (EDS) 91 using Computed Tomography (CT) technology, a People Screening Unit (PS) 93 used to inspect people by a particle trace detection technique.
  • the integrated system may also comprise also human user interface with a Graphics User Interface (GUI) 95, allowing a user to control the entire system via an input device and monitor system operation on a screen. Data flowing back and forth between the various units through a data communication interface link that may be electrically wired, optically wired or a wireless data communication link.
  • GUI Graphics User Interface
  • the particulate extraction system may benefit from an a priori assessment of the contents of an OUI.
  • parameters may be derived and used to optimize the extraction process.
  • a weight of an OUI measured on a conveyor or in a tray may be used to estimate characteristics of the OUI.
  • the particular extraction and analysis device may provide relevant inputs to other screening systems. For example, if the particulate extraction device imposes a vibration on the OUI, it may measure the response of the contents of the OUI to this mechanical stimulation. Thus, in turn, may be used to assist in interpretation of radiographic data.
  • various devices can estimate a risk profile for a passenger, even if no one device determines any single screening procedure to be outside of a normal range. Therefore, the present invention provides a sensor fusion environment for leveraging the large amount of information available from multiple sensors, which can improve each other's performance, or produce results that none of the sensors individually could produce.
  • the screening device may also be integrated with other types of risk management systems, such as law enforcement databases, passenger manifest lists, and the like.
  • system may include the physical layer of a standard interface as well as a programming layer implemented by an Application Programming Interface (API), allowing the system to be integrated along with other inspection systems into an integrated security system.
  • API Application Programming Interface

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Abstract

La présente invention concerne un système d'extraction de particules, comprenant une chambre, présentant une région d'inspection des objets. Au moins un objet est placé dans la région d'inspection des objets, et est soumis à des écoulements gazeux ou de divers types, qui visent à détacher les particules de l'objet et à les suspendre dans l'écoulement gazeux. Les particules peuvent être analysées à l'intérieur de la chambre, ou transportées à l'extérieur pour analyse. De préférence, les particules sont concentrées avant analyse.
PCT/US2007/088789 2006-12-28 2007-12-24 Procédé et appareil de collecte de traces Ceased WO2008083138A1 (fr)

Applications Claiming Priority (2)

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IL180414A IL180414A0 (en) 2006-12-28 2006-12-28 Method and apparatus for trace collection
IL180414 2006-12-28

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Cited By (20)

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US9012241B2 (en) 2010-07-27 2015-04-21 Lawrence Livermore National Security, Llc Rapid detection and identification of energetic materials with surface enhanced raman spectrometry (SERS)
WO2015188143A1 (fr) * 2014-06-06 2015-12-10 LLT International (Ireland) Ltd. Systèmes et procédés de traitement de matières solides au moyen d'ondes de choc produites dans un tourbillon gazeux supersonique
US9452434B1 (en) 2015-04-17 2016-09-27 LLT International (Ireland) Ltd. Providing wear resistance in a reactor configured to facilitate chemical reactions and/or comminution of solid feed materials using shockwaves created in a supersonic gaseous vortex
US9608547B2 (en) 2012-01-31 2017-03-28 The Penn State Research Foundation Microfluidic manipulation and sorting of particles using tunable standing surface acoustic wave
US9606086B2 (en) 2012-08-01 2017-03-28 The Penn State Research Foundation High-efficiency separation and manipulation of particles and cells in microfluidic device using surface acoustic waves at an oblique angle
US9757699B2 (en) 2012-11-27 2017-09-12 The Penn State Research Foundation Spatiotemporal control of chemical microenvironment using oscillating microstructures
US10137456B1 (en) 2014-06-06 2018-11-27 LLT International (Ireland) Ltd. Reactor configured to facilitate chemical reactions and/or comminution of solid feed materials
US10427129B2 (en) 2015-04-17 2019-10-01 LLT International (Ireland) Ltd. Systems and methods for facilitating reactions in gases using shockwaves produced in a supersonic gaseous vortex
US10434488B2 (en) 2015-08-11 2019-10-08 LLT International (Ireland) Ltd. Systems and methods for facilitating dissociation of methane utilizing a reactor designed to generate shockwaves in a supersonic gaseous vortex
US10550731B2 (en) 2017-01-13 2020-02-04 LLT International (Ireland) Ltd. Systems and methods for generating steam by creating shockwaves in a supersonic gaseous vortex
CN111077339A (zh) * 2019-12-26 2020-04-28 哈尔滨工程大学 一种piv粒子回收装置
WO2020099335A1 (fr) * 2018-11-13 2020-05-22 Iconal Technology Ltd Dispositif et procédé de balayage d'objets
RU2748054C1 (ru) * 2020-06-02 2021-05-19 Игорь Владимирович Шерстов Лазерный оптико-акустический газоанализатор и резонансный дифференциальный оптико-акустический детектор
US11203725B2 (en) 2017-04-06 2021-12-21 LLT International (Ireland) Ltd. Systems and methods for gasification of carbonaceous materials
WO2022074198A1 (fr) * 2020-10-10 2022-04-14 Hooman Khajehnouri Procédé de désinfection à recyclage sélectif d'aérosol, à base de cyclone, faisant intervenir un piège optique à longueurs d'ondes multiples à rayons laser multiples
CN116429989A (zh) * 2023-06-15 2023-07-14 中国人民解放军63968部队 一种大气环境检测系统
US11708986B1 (en) * 2022-07-12 2023-07-25 Intellytic Ventures Ltd Smart IoT energy saving sound wave air filter system and use for air purifiers and a method of air filtration thereof
US20250052660A1 (en) * 2023-08-08 2025-02-13 Dish Network L.L.C. Device inspection apparatus for determining cleaning necessity and related methods
KR102893194B1 (ko) 2020-06-03 2025-11-28 테우스 일렉트로닉 게엠베하 운트 컴파니 카게 입자 크기 분포의 적어도 하나의 특징 변수를 결정하는 방법 및 측정장치를 포함하는 장치

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US6848325B2 (en) * 2001-04-04 2005-02-01 Sandia Corporation Explosives screening on a vehicle surface
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Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8573060B2 (en) 2008-12-05 2013-11-05 The Penn State Research Foundation Particle focusing within a microfluidic device using surface acoustic waves
US9012241B2 (en) 2010-07-27 2015-04-21 Lawrence Livermore National Security, Llc Rapid detection and identification of energetic materials with surface enhanced raman spectrometry (SERS)
US9608547B2 (en) 2012-01-31 2017-03-28 The Penn State Research Foundation Microfluidic manipulation and sorting of particles using tunable standing surface acoustic wave
US9606086B2 (en) 2012-08-01 2017-03-28 The Penn State Research Foundation High-efficiency separation and manipulation of particles and cells in microfluidic device using surface acoustic waves at an oblique angle
US9757699B2 (en) 2012-11-27 2017-09-12 The Penn State Research Foundation Spatiotemporal control of chemical microenvironment using oscillating microstructures
RU2681489C2 (ru) * 2014-06-06 2019-03-06 ЭлЭлТи ИНТЕРНЭШНЛ (АЙЭЛЭНД) ЛТД. Система и способ для обработки твердых материалов с использованием ударных волн, создаваемых в сверхзвуковом газовом вихре
US9724703B2 (en) 2014-06-06 2017-08-08 LLT International (Ireland) Ltd. Systems and methods for processing solid materials using shockwaves produced in a supersonic gaseous vortex
US10137456B1 (en) 2014-06-06 2018-11-27 LLT International (Ireland) Ltd. Reactor configured to facilitate chemical reactions and/or comminution of solid feed materials
WO2015188143A1 (fr) * 2014-06-06 2015-12-10 LLT International (Ireland) Ltd. Systèmes et procédés de traitement de matières solides au moyen d'ondes de choc produites dans un tourbillon gazeux supersonique
US9452434B1 (en) 2015-04-17 2016-09-27 LLT International (Ireland) Ltd. Providing wear resistance in a reactor configured to facilitate chemical reactions and/or comminution of solid feed materials using shockwaves created in a supersonic gaseous vortex
US10562036B2 (en) 2015-04-17 2020-02-18 LLT International (Irelant) Ltd. Providing wear resistance in a reactor configured to facilitate chemical reactions and/or comminution of solid feed materials using shockwaves created in a supersonic gaseous vortex
US10427129B2 (en) 2015-04-17 2019-10-01 LLT International (Ireland) Ltd. Systems and methods for facilitating reactions in gases using shockwaves produced in a supersonic gaseous vortex
US10434488B2 (en) 2015-08-11 2019-10-08 LLT International (Ireland) Ltd. Systems and methods for facilitating dissociation of methane utilizing a reactor designed to generate shockwaves in a supersonic gaseous vortex
US10550731B2 (en) 2017-01-13 2020-02-04 LLT International (Ireland) Ltd. Systems and methods for generating steam by creating shockwaves in a supersonic gaseous vortex
US11203725B2 (en) 2017-04-06 2021-12-21 LLT International (Ireland) Ltd. Systems and methods for gasification of carbonaceous materials
WO2020099335A1 (fr) * 2018-11-13 2020-05-22 Iconal Technology Ltd Dispositif et procédé de balayage d'objets
US12019203B2 (en) 2018-11-13 2024-06-25 Iconal Technology Ltd. Device and method for scanning items
CN111077339A (zh) * 2019-12-26 2020-04-28 哈尔滨工程大学 一种piv粒子回收装置
CN111077339B (zh) * 2019-12-26 2022-02-22 哈尔滨工程大学 一种piv粒子回收装置
RU2748054C1 (ru) * 2020-06-02 2021-05-19 Игорь Владимирович Шерстов Лазерный оптико-акустический газоанализатор и резонансный дифференциальный оптико-акустический детектор
KR102893194B1 (ko) 2020-06-03 2025-11-28 테우스 일렉트로닉 게엠베하 운트 컴파니 카게 입자 크기 분포의 적어도 하나의 특징 변수를 결정하는 방법 및 측정장치를 포함하는 장치
WO2022074198A1 (fr) * 2020-10-10 2022-04-14 Hooman Khajehnouri Procédé de désinfection à recyclage sélectif d'aérosol, à base de cyclone, faisant intervenir un piège optique à longueurs d'ondes multiples à rayons laser multiples
US11708986B1 (en) * 2022-07-12 2023-07-25 Intellytic Ventures Ltd Smart IoT energy saving sound wave air filter system and use for air purifiers and a method of air filtration thereof
CN116429989A (zh) * 2023-06-15 2023-07-14 中国人民解放军63968部队 一种大气环境检测系统
US20250052660A1 (en) * 2023-08-08 2025-02-13 Dish Network L.L.C. Device inspection apparatus for determining cleaning necessity and related methods

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