Patent Application
20120278002
Ever since letters contaminated with weapons-grade Bacillus anthracis (anthrax) spores passed through the United States Postal Service (USPS) in the fall of 2001 and the “letter bombs” mailed in the 1980s, there has been a heightened awareness that chemical, biological, radiological or explosive threats could be hidden in an item of mail. Thus, there is an ongoing need to develop new technologies to address such potential threats. Due to the volume of mail that must be screened, it is desirable that any such screening technology be cost effective.
The USPS is not the only organization that delivers mail and parcels. Commercial shippers and the U.S. military also manage the shipment and delivery of large volumes of parcels. It would be desirable to provide a screening technology that is sensitive and cost effective. Such a technology will preferably be capable of screening for chemical, biological, radiological, nuclear or explosive (CBRNE) threats. Similarly, such a technology would be useful for screening luggage and cargo prior to transportation.
Disclosed herein are a plurality of concepts for screening mail and parcels for a plurality of threats.
In one exemplary embodiment, a system is configured to automatically screen an item of mail for the presence of at least one of three different types of threat agents selected from a group consisting of a radiological agent, a toxic chemical agent, a bio-threat agent, and an explosive agent. In addition, the system also includes at least three of the following components: a radiation detection component, a toxic chemical detection component, a puffer-based bio-threat sampling component, and an explosive detection component. The radiation detection component is configured to detect if radiation is associated with the item of mail. The toxic chemical detection component is configured to determine if a toxic chemical agent is associated with the item of mail. The puffer-based bio-threat sampling component is configured to collect a bio-threat sample to be analyzed to determine if a bio-threat agent is present on the item of mail and it collects the bio-threat sample by filtering a gaseous fluid used to dislodge bio-threat particles associated with the item of mail. The explosive detection component comprises at least one element selected from a group consisting of: a vapor concentrator; a sampling medium configured to be directly swiped over a surface of the item of mail; a vapor based sampler with surface heating; a non-contact desorption ionization based sampler; and a puffer-based particulate sampler, the puffer-based particulate sampler being configured to collect particulates disposed on a surface of an item of mail. The explosive detection component is configured to determine if an explosive agent is associated with the item of mail. Even where a majority of the bio-threat agent, explosive agent, or toxic agent is contained within the parcel, it is highly likely that detectable traces will be present on the surface of the parcel. The system optionally includes an X-ray based imager. The system optionally includes the capability to measure the item's size and weight.
In another exemplary embodiment, a system is configured for automatically screening mail for CBRNE threats in an item of mail. The system comprises a radiation detection component, a relatively low flow sampling component, and a relatively high flow sampling component. The relatively low flow sampling component is configured to detect if either a toxic chemical agent or an explosive agent is associated with the item of mail, and it includes a mass spectrometer and an explosive detector. The relatively high flow sampling component is configured to automatically collect a bio-threat sample to be analyzed to determine if a bio-threat agent is associated with either the item of mail or a batch of mail containing the item of mail. The radiation detection component is configured to detect if radioactive material is associated with the item of mail. The system optionally includes a sizing component configured to determine at least one dimension of the item of mail. The system optionally includes a component to measure the weight of the item of mail.
In yet another exemplary embodiment, a mail screening system is configured to automatically screen an item of mail for at least one threat selected from the group consisting of CBRNE threats. The system includes a detector configured to analyze a sample collected by the system, where the sample is associated with the item of mail, to determine if at least one threat selected from the group consisting of CBRNE threats is associated with the item of mail. The system also includes an automated sample arm; a means to achieve a relative motion between the automated sample arm and the item of mail; a sampling substrate coupled to the automated sample arm, and means to intentionally remove the sample from the sampling substrate and convey the sample to the detector for analysis. In a particularly preferred but not limiting embodiment the detector is an explosives detector. The sampling substrate comprises a generally planar surface, and the automated sample arm is configured to position the sampling substrate such that the generally planar surface of the sampling substrate wipes a generally planar portion of the item of mail as the sampling substrate contacts the item of mail while there is relative motion between the automated sample arm and the item of mail. The system preferably includes a light curtain configured to determine at least one dimension of the item of mail, to facilitate proper positioning of the automated sample arm relative to the item of mail.
In another embodiment, the sampling substrate is replaced with a thermal desorption and/or a desorption ionization sampling device. The thermal desorption and/or desorption ionization sampling device is coupled to the automated sample arm. The sample arm is positioned such that the thermal desorption and/or desorption ionization sampling device is in close proximity to the surface of the item of mail. Upon activation of the thermal desorption and/or a desorption ionization sampling device, analytes on the surface of the item of mail are released from the surface and presented to a detector for analysis. The system preferably includes a light curtain configured to determine at least one dimension of the item of mail, to facilitate proper positioning of the automated sample arm relative to the item of mail.
Another aspect of the concepts disclosed herein is an exemplary method for automatically screening an item of mail for at least one threat selected from the group consisting of CBRNE threats. A sampling substrate is positioned such that the sampling substrate is in contact with at least a portion of the item of mail. A relative motion is achieved between the sampling substrate and the item of mail, thereby collecting the sample on the sampling substrate, such that the sample is retained upon the sampling substrate until the sample is intentionally removed. When the sample is intentionally removed from the sampling substrate, it is conveyed to a detector configured to analyze the sample. The sample is analyzed with the detector to determine if at least one threat selected from the group consisting of CBRNE threats is associated with the item of mail. The sampling substrate is further regenerated for future use by heating the sampling substrate for a period of time sufficient to remove substantially all remaining traces of the sample from the sampling substrate. Preferably at least one dimension of the item of mail is determined before sampling, to facilitate properly positioning the sampling substrate relative to the item of mail.
In yet another exemplary method for automatically screening an item of mail for CBRNE threats, the item of mail is automatically scanned using a radiation detector that does not require obtaining a physical sample from the item of mail, in order to screen for radiological and nuclear threats. The item of mail is automatically screened for an explosive threat by collecting a sample from the item of mail by automatically wiping at least one surface of the item of mail using a sampling substrate that retains an explosive sample thereon until the explosive sample is intentionally removed. The sampling substrate is heated to volatilize at least a portion of the explosive sample, and the volatilized explosive sample is directed to an explosive detector. Further, a vapor based sample is automatically collected from an ambient gaseous environment proximate the item of mail and the vapor based sample analyzed to detect a chemical threat associated with the item of mail. A jet of gaseous fluid is automatically directed over at least a portion of the item of mail after collecting the vapor based sample, to dislodge any particles retained on the item of mail, and an ambient gaseous environment proximate the item of mail is filtered to remove particles entrained in the gaseous environment, thereby obtaining the particle based sample that can be tested for a biological threat.
In other embodiments, the sampling substrate coupled to the automated sample arm is replaced with an indirect analyte releasing mechanism, such as, but not limited to, a thermal desorption device or a desorption ionization device. Obtaining a sample from the item of mail is achieved without physically touching the item. In these embodiments, ambient air and ambient pressure surface sampling techniques for low volatility chemical(s) of interest, including include localized thermal desorption techniques, such as pulsed lasers or light focused from flash lamps; or desorption ionization based sampling techniques including desorption electrospray ionization (DESI), low temperature plasma (LTP), atmospheric pressure matrix assisted laser desorption ionization (AP-MALDI), and direct analysis in real time (DART). The released analytes are screened for an explosive threat using an explosive detector.
This Summary has been provided to introduce a few concepts in a simplified form that are further described in detail below in the Description. However, this Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
Various aspects and attendant advantages of one or more exemplary embodiments and modifications thereto will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
a is a functional block diagram of an exemplary mail screening system that includes an automated sample arm.
b is a functional block diagram of an exemplary mail screening system that includes an automated sample arm with a thermal desorption and/or a desorption ionization surface sampling device attached thereto.
a is an artist's representation of different embodiments of the automated sample arm of the mail screening system of
b is a representation of different embodiments of the automated sample arm with a thermal desorption and/or a desorption ionization surface sampling device coupled thereto of the mail screening system of
a is a flow chart of steps for utilizing the mail screening system of
b is a flow chart of steps for utilizing the mail screening system of
a depicts one desorption ionization surface sampling embodiment.
b depicts a close-up view of one embodiment depicted in
Figures and Disclosed Embodiments Are Not Limiting
Exemplary embodiments are illustrated in referenced Figures of the drawings. It is intended that the embodiments and Figures disclosed herein are to be considered illustrative rather than restrictive. No limitation on the scope of the technology and of the claims that follow is to be imputed to the examples shown in the drawings and discussed herein.
The exemplary embodiments described herein facilitate CBRNE threat screening of a variety of types of mail. Significantly, such screening systems can be readily integrated into the existing military mail sorting process. It should be recognized that the concepts disclosed herein are not limited to screening mail for the military; rather, the concepts disclosed herein can be beneficially employed to screen parcels for the military and other users. As used herein, the phrase item of mail is intended to encompass parcels, packages and letters, and any container, box, or case in which an item is packed for shipping and delivery. The term parcel, as used herein, is thus also intended to include luggage and any container packed with personal belongings for transportation on airplanes, cruise ships, or trains.
Various portions of the specification and claims refer to sampling for a hazardous material on the surface of a parcel, or a hazardous material associated with a parcel. The term surface of a parcel encompasses all external surfaces of a parcel (noting that a statement or claim reciting that a surface of the parcel is sampled simply indicates that at least one external surface is sampled, not necessarily all external surfaces). The term associated with should be understood to include hazardous materials that are contained within a parcel, in addition to hazardous materials disposed on an external surface of a parcel. Hazardous materials on the surfaces of parcels are generally deposited on the outer surface of a parcel by individuals responsible for placing the hazardous material in the parcel (it is surprisingly difficult to avoid leaving traces of such hazardous materials on external parcel surfaces). Hazardous materials on surfaces of a parcel can be sampled either by dislodging the hazardous material (using for example, jets or puffs of compressed gases such as air, vibrating the parcel, or using high intensity flash lamps to vaporize hazardous material from parcel surfaces), or by physically wiping a portion of the external parcel surfaces using a sampling substrate (followed by removing the sample from the substrate for analysis). Hazardous materials contained within a parcel are generally more difficult to sample. However, parcels can be scanned to detect any radiation that might be emitted from a radioactive material contained within a parcel. Air samples from the exterior surface of a parcel can be collected to obtain a sample of a volatile material leaking out of a parcel in trace amounts. X-ray images can be used to determine if the parcel includes any sealed containers that might merit closer examination of that parcel. Less desirably, very small openings (i.e., openings too small to negatively affect the structural integrity of a parcel) can be made in a parcel to collect a sample of air contained within the parcel.
Before discussing specific screening system embodiments in detail, it may be helpful to first explain the types of components that can be used to detect the chemical, explosive, biological and radiation threats, and then describe exemplary screening system embodiments which employ one or more of such components.
Material Handling Equipment: While not specifically required, material handling equipment, such as conveyor systems (generally a conveyor belt similar to those employed in conventional mail processing rooms and baggage handling systems in airports, or roller conveyors employed in warehouse facilities), can be beneficially incorporated into the screening systems disclosed herein.
Design Considerations: Exemplary, but not limiting, design considerations include the following. Providing modular and scalable screening systems. Providing mail/parcel screening systems capable of achieving a parcel throughput of about 30 seconds or less. Providing mail/parcel screening systems that require no more than two operators per system. Providing mail/parcel screening systems capable of screening parcels up to 2′×3′×4′ in dimension. Providing mail/parcel screening systems including the ability to track individual parcels using radio frequency identification (RFID) tags, such that RFID tag readers can be incorporated into any of the systems described below. Providing screening systems configured to screen mail for one or more of the following types of threat agents: chemical agents, explosive agents, biological agents and radiological/nuclear agents.
Parcel Identification and System Control: In an exemplary, but not limiting embodiment, each parcel or item of mail is individually labeled with a unique identifier, such that data collected by the screening system unique to that parcel or item of mail can be stored in a database. RFID tags and machine readable optical codes (such as barcodes) represent exemplary identification technologies. A computer (i.e., a processor combined with a memory storing software to be executed by the processor) represents a particularly preferred type of system control. Such a computer can control system components such as material handling equipment, valves, fans, pumps and blowers (which may be employed in various sampling and detection components), detectors (which may include one or more of explosive detectors, toxic chemical detectors, radiation detectors, and bio-threat samplers and/or bio-threat detectors), and operator interfaces. The computer will collect and store data from each of the sensors, and evaluate the data to trigger an alarm (audible, visual, or a combination thereof) when a threat is detected. It should be recognized that other types of controllers, such as custom circuits and hardwired controllers, could also be employed.
Vapor Sampling for Detecting Traces of Explosives/Chemicals: A critical factor in reliable detection of explosives or other trace residues on parcels is effective sampling. Research and development efforts have often focused on increasing a sensor's sensitivity to target analytes. Regardless of how sensitive a detector is, it will only successfully detect explosives if a sufficient sample is properly collected and delivered to the sensor. Collection of explosive analyte is complicated by the fact that the equilibrium vapor pressure of many explosives is very low. Further, the flux rate of explosive vapor from contaminated surfaces is low, and this flux is typically into a large volume of air. Once explosive vapor is liberated from a surface, it diffuses through the boundary layer of air near the contaminated surface and mixes with the air outside the boundary layer. Turbulent dispersion mechanisms lead to dispersion of the vapor away from its source. The plume of vapor that results can be highly fragmented, resulting in a heterogeneous sampling space that contains air that is mostly free of explosive.
Trace detection attempts over very large sample volumes have an extremely low probability of detection, even if there are volumes of air that contain sufficient concentrations of analyte. Unless the contaminated surface has stayed in a region of stagnant air, the concentration of explosive vapor in the air near an explosive device is very low, likely orders of magnitude below that of the equilibrium vapor concentration. To overcome this problem, pre-concentrators are utilized to enrich the concentration of target analyte in a sample. Pre-concentrators contain a substrate coated with or constructed from a material that sorbs (sometimes selectively) target analyte vapors from air as the air is drawn through the pre-concentrator. Once the desired volume of air is run through or over the pre-concentration medium, the pre-concentrator is typically heated rapidly to desorb the target analyte from the sorbent material, and the vapor generated is then entrained into a low volume flow of carrier gas that sweeps the sample into a sensor for analysis. In this way, the explosive vapor from a relatively large volume of air is delivered to the sensor in a relatively smaller volume of air, effectively increasing the concentration of explosive in the sample.
To maximize the probability of collecting enough vapor on the pre-concentration medium, many systems either collect vapor for long periods of time at relatively low to relatively medium flow rates, or collect for shorter time periods with relatively higher flow rates. Both of these techniques have significant problems with respect to mail screening. First, there are finite limits to the maximum flow rates, as a function of the pre-concentration surface. In general, the lower the flow rate across the surface, the higher the percentage of particles that are deposited upon the surface. As the flow rate increases, the probability of the target vapor particles being deposited upon the pre-concentration medium actually begins to decrease. This problem can be diminished by increasing the size of the pre-concentration surface, while lowering the flow rate (keeping the volumetric flow constant). However, too much of an increase will then necessitate a second stage of pre-concentration before the sample is in a small enough volume to present to currently available trace detectors in a timely fashion. In short, bulk sampling of the vapor head space over the surface of a target is an impractical solution for field deployment, due to the extended time periods required for both low sampling rates and higher sampling rates combined with a secondary desorption.
Alternatively, particles containing or comprised of explosive material can be stripped from the surface of the parcel with the use of pulsed air jets (puffers) or with an “air knife,” and then filtered or concentrated. Since this approach liberates the aerosol into a relatively large volume of air, two techniques have been employed to concentrate the explosive. In portals currently used to screen passengers in airport security check points, puffers are coupled to high-flow-rate filters. After the filtering is completed, the filter is heated to thermally desorb the explosive vapor. Alternatively, a virtual impactor can be used to concentrate the particulates prior to deposition onto a thermal desorption surface.
As an alternative to puffer-based or bulk air sampling, directional sampling provides great benefits in reducing the volume of air sampled in order to collect the same number of useful particles for deposition onto the pre-concentration medium. An Aaberg nozzle is an exemplary structure that can be used for directional vapor sampling. The straightforward benefits of directional suction versus simple suction devices are based in the fact that simple suction devices draw fluid from all directions equally, and consequently as the distance of the target volume of air from the input nozzle grows, the volume of air that must be sampled in order to achieve capture of target particles increases at a cubic rate. The relationship between the distances from the target and the increased volume of air required for sampling becomes a squared relationship. Additionally, the Aaberg nozzle increases the speed of the moving air, decreasing sample time.
As will be described in greater detail below, in at least one embodiment disclosed herein, a mail/parcel screening system will include a relatively large (½″ diameter) Vorberg nozzle. The nozzle is set at a pre-determined height above the target parcel, and the nozzle runs in Aaberg mode for four (4) to five (5) seconds, sucking up any vapor particles onto a pre-concentration medium. After the Aaberg mode sampling completes, the nozzle will switch into vortex mode, and will then collect particulate material from the surface of the parcel. The two phases of sampling will collect onto separate media so that following the vapor collection phase, the desorption process can be performed on the vapor collection medium while the particle collection phase is proceeding. By pipelining the vapor and particulate testing in this fashion, the overall throughput rate of the system can be increased. In other words, a single nozzle will initially collect vapors, and will then be operated in a vortex mode to collect particles. Such a screening system is configured to collect and provide sample material to both explosive and chemical detection system components during screening.
With respect to chemical screening, in at least some of the screening systems disclosed herein, a sampling subsystem will interconnect with and supply concentrated material to an integrated mass spectrometer for evaluation of potential chemical threats. Preferably, the instrument will be capable of two levels of mass spectrometry, or MS/MS. The capability of using two levels of mass spectrometry yields additional levels of molecular fingerprinting, wherein signals of interest are isolated from the background clutter and further processed to generate highly reproducible, low-noise secondary signatures for chemical identification and confirmation. This tandem MS detection process provides the necessary sensitivity and specificity to distinguish a wide range of targeted chemical compounds in complex matrices in a very rapid analysis.
With respect to explosive screening, in at least some of the screening systems disclosed herein, a sampling subsystem will provide material for trace explosives detection.
In addition to puffers and air knives, other techniques for dislodging traces of hazardous materials from a parcel include applying a physical force to a parcel (such as vibrating a parcel, or slapping the parcel with a member designed to apply a force to the parcel without damaging the parcel), or thermal desorption, including heating the parcel (for example, by passing the parcel through a heated chamber), or directing flashes of high intensity light, for example, from flash lamps or pulsed lasers, at parcel surfaces to remove hazardous materials that may be disposed on the surface of the parcel (heat may also induce materials disposed within the parcel to be volatile and leak out such that they can be detected). With respect to the use of pulsed lasers or flash lamps, the delivery of localized energy to the parcel surfaces during a very short period of time (flash lamps characteristically are energized very briefly). Without being limited to any particular theory, the use of flash lamps or pulsed lasers is believed to likely heat the air immediately adjacent to the parcel surface or locally heat the surface of the parcel thereby releasing the target analyte for collection and analysis. Thus, this embodiment does not require heating of the entire parcel.
In the pulsed laser thermal desorption method, any wavelength of light in the electromagnetic spectrum can be used, preferably the infrared wavelength, and infrared lasers are used. The preferable range for the laser would be about 0.7-10 micron wavelength range, and more preferably about 0.7-2.0 microns. In the flash lamp thermal desorption method, any wavelength of light in the electromagnetic spectrum can be used. Flash lamps emit a broad range of visible and infrared light.
Desorption ionization sampling techniques suitable for the various embodiments disclosed herein, include ambient ionization methods, for example, desorption electrospray ionization (DESI), low temperature plasma (LTP), direct analysis in real time (DART), and atmospheric pressure matrix assisted laser desorption ionization (AP-MALDI). These ambient ionization methods are performed in ambient air as opposed to in a vacuum.
In general these localized heating and desorption ionization techniques eliminate the need for sample pretreatment. As shown in an exemplary embodiment of
In one embodiment, sampling tube 506 is also attached to automated sample arm. Positioning and adjustments to position of both sampling tube 506 and sampling device 87a can be done manually or automatically. Both sampling device 87a and sampling tube 506 may have gears, pulleys, or electromechanical mechanisms, including servo motors attached to achieve the optimal position with respect to the other device as well as with the surface of the parcel. Released analytes are drawn into the sampling tube 506 via vacuum pumps (not shown) positioned at the back end of the explosive detector (not shown), e.g. mass spectrometer unit. The explosive detector, pump, and sampling tube 506 are in fluid communication. In alternative embodiments, sampling tube 506 may be charged thereby attracting released analytes (e.g. ions) from the parcel surface to sampling tube 506. In an alternative embodiment, selected chemicals can be added to the spray solution to provide specificity for the ionization of particular types of analytes. It should be appreciated that in other embodiments, other desorption ionization sampling devices may be coupled to automated sample arm as shown in
As described above, the released analytes from the desorption ionization and thermal sampling techniques are also presented to the sampling tube 506 and ultimately to the explosive detector as described above.
Not depicted in the figures, at least one cable, will be attached to sampling device 87a and sampling tube 506. For example, a cable may hang from a surface and/or be wrapped around the automated sample arm to connect with the surface sampling device 87a and sampling tube 506. For example, a fiber optic cable will supply light from a source (not depicted) for the pulsed laser, flash lamp, and a laser used in AP-MALDI. Conduit or tubing will also be connected to thermal desorption and/or desorption ionization sampling device from a source (not depicted) to supply the solvent and/or discharge gas as used in DESI, LTP, and DART sampling techniques. In addition, power from a voltage source (not depicted) will also to connect to the surface sampling device 87a to supply electrical power.
As should be appreciated, the exact methodology for the configuration of and attachment of the surface sampling device 87a including the sampling tube 506 with the automated sample arm, as well as the interconnection for the supply of power, light, gases from their respective sources will not be discussed herein.
Radiation Threat Detection Components: In at least one exemplary embodiment, the screening system is capable of automatically screening all items of mail in order to determine whether or not the item of mail is a source of radiation. In one configuration, the device utilized to determine whether or not a source of radiation is present in an item of mail is a radiation scintillation portal. The radiation scintillation portal is utilized as a broad, non-specific screening step. If a signal is detected indicative of a radiological material, the detection is followed up with a secondary screening that is manual. This secondary screening is directed to providing a more specific radiological identification step in order to determine if the initial signal is a benign detection or a signal indicative of a dirty bomb or even Special Nuclear Materials. An advantage of this automated detect and manual identify technique is cost; the scintillation portals that simply detect radiation are significantly less expensive than technologies that automatically detect and identify a radioisotope.
A more expensive alternative is to employ a detector that can automatically detect the presence of radiation and to identify the source of the radiation. One such device is based on a NaI(T1) gamma ray detector with digital electronics that can detect radioactivity at levels equivalent to 5 nano Curies of unshielded Cs-137. Naturally occurring isotopes, especially K-40, will be identified and give no alarm. The detector assembly is stabilized and calibrated. A two (2) inch lead and steel enclosure ensures shielding of background radiation and provides for high detection efficiency. The measurement time per parcel can be adjusted and defines the minimum detectable activity (MDA)—e.g., 7 seconds: 10 nCi; 30 seconds: 5 nCi; 60 seconds: 3.5 nCi; 120 seconds: 2.5 nCi. However, it is assumed that the system measurement time will normally be determined by explosives sampling and detection requirements. Those skilled in the art will recognize that actual MDAs may vary from the nominal values provided above. Note that the incorporation of the detect and identify technology provides more than the broad, non-specific screening step provided by the radiation scintillation portal. More specifically, the radiation level of the actual parcel as well as the detected threat isotope is displayed on a central computer. Thus, the use of this system component negates any manual secondary screening for identifying the isotope. In addition, in case of an alarm, in some embodiments such technology can be configured to display a warning message, activate a warning indicator light, send a warning message to another member of the security team, or activate an audible alarm.
Biological Threat Detection Components The explosive detection components, toxic chemical detection components, and radiation detection components discussed above detect such threats in real-time (i.e., for each item of mail individually, while that item of mail is moving through the screening system). In order to achieve a functional screening system of modest cost, many of the screening systems disclosed herein will incorporate an automatic bio-threat sampling subsystem, which is configured to collect an aggregate sample for a batch of mail processed in the screening system. For example, a single bio-threat sample can be accumulated over a four or eight hour shift or for a particular batch of mail. Prior to releasing that batch of screened mail for delivery, the aggregate bio-threat sample is analyzed. If no bio-threat is detected, then the batch of mail is released for delivery. If a potential bio-threat is found, the batch is set aside for further investigation, to identify the item or items of mail comprising the source of the bio-threat agent. Real-time sensors for bio-threats would be preferable to batch testing for bio-threats, but the sensors that are commercially available today suitable for this purpose rely upon laser-induced fluorescence detection, and such techniques are known to have high false alarm rates in the presence of paper dust. If a suitable sensor for real-time detection of bio-threats in the presence of paper dust were to become available in the future, it would be desirable to incorporate such a sensor into the biological sampling component.
In an exemplary embodiment, but not limiting embodiment, air proximate each item of mail in a batch of mail is filtered to collect a bio-threat sample. In at least one embodiment, jets of gaseous fluid are directed at each item of mail, so that any particles on the surface of the item of mail become entrained in the gaseous fluid, to be filtered by a dry filter unit (DFU). Apparatus configured to provide such fluid jets are commonly referred to as puffers or air knives (as they puff air/fluid at an object). It should be noted that the vapor sampling discussed above could be considered to correspond to a low flow environment, whereas collecting the bio-threat sample using a puffer would be considered to be a high flow environment.
In at least one embodiment, the item of mail is placed into a chamber that is isolated from the ambient environment (using either a physical barrier, a pressure barrier, or an air curtain). Air from within the chamber is continuously passed through the DFU to obtain the bio-threat sample. Air from puffers or air knives may also be added to the chamber to provide some high-shear, turbulent airflow at the surface of the parcel to help aerosolize any biological threats which may be present.
Screening system operators can determine how to break up large volumes of mail into batches, such that a bio-threat sample is collected from the DFU for each batch. Smaller batch sizes have the advantage of containing fewer items of mail that need to be individually examined if a bio-threat sample indicates that one of the items of mail in the batch contains a bio-threat. Larger batch sizes have the advantage of enabling larger volumes of mail to be processed without interrupting the screening operations to remove a bio-threat sample from the DFU. Custom DFUs can be fabricated to enable a filter change without interrupting the screening process (i.e., by enabling rapid filter change).
In at least one exemplary embodiment, a separate aerosol collector is employed to collect an additional bio-threat sample (i.e., in addition to the bio-threat sample collected by the DFU). If desired, the separate aerosol collector can be connected to an automated biological agent identification system. In yet another alternative configuration, a real-time biological-threat sensor can also be incorporated. In such a configuration, the real-time biological-threat sensor can be used to activate the agent identification system to analyze the sample for specific biological agents. Automated biological agent identification systems are commercially available, and are based on either polymerase chain reaction (PCR) amplification and detection of gene sequences associated with specific bio-threats (if present), or on antibody-antigen binding.
X-Ray Imaging Based Explosive Screening In some embodiments disclosed herein, an X-ray imaging based explosive screening component is incorporated into the screening system (preferably in addition to the other explosive detection technologies discussed above). In one exemplary embodiment, the X-ray screening component automatically images each item of mail, and a trained operator reviews the image to look for signs of an explosive agent. Useful X-ray imaging systems include 2-D X-ray, backscatter X-ray, two-power X-ray, and computed tomographic (CT) scanning (or 3-D) X-ray.
In the alternative, no operator reviews the X-ray images as they are acquired, rather an expert system configured to automatically analyze each image collected is employed. Thus, in the event that the software analyzing the scanned image detects a potential threat, the X-ray system can send a signal to the system controller indicating that a secondary screening is necessary, such as a review of the image by a trained operator.
In yet another embodiment, no operator reviews the X-ray images as they are acquired; rather the image generated by the X-ray component is stored in a database. Thus, in the event that a threat is detected, the stored image can be retrieved and analyzed in a secondary screening.
In an exemplary embodiment, the X-ray system is disposed at a predetermined distance from the radiation threat detector system components. This distance is a function of the distance required to prevent X-rays generated by the X-ray imaging subsystem from interfering with the radiation detection component. Shielding can be incorporated to reduce the deleterious impact of stray X-rays.
An exemplary radiation detection component is a scintillation portal, such as are available from Saint-Gobain, Atlantic Nuclear, Thermo-Fisher, and ICx Technologies. Preferably the radiation detector will be capable of detecting and identifying even small amounts of shielded radioactive material, although it should be recognized that a simpler embodiment would provide automatic detection without identification, Such embodiments are somewhat less preferred, as they would require secondary screening of the parcel to identify the isotope that triggered the alarm. In a particularly preferred embodiment, the radiation detector will be sensitive to levels equivalent to five nano-curies of unshielded cesium-137, and naturally occurring isotopes, especially potassium 40, will be identified and will not trigger an alarm. Similarly, medical or industrial isotopes can be identified as such. In at least one embodiment, the radiation level of the item of the mail, as well as the detected threat isotope, will be displayed on an operator user interface (or controller 21). When a radioactive threat is detected and identified, a warning message can be displayed on the operator user interface, and if desired a color-coded light can be activated to indicate the threat level. Audible or electronic message alarms can be activated if desired.
Toxic chemical detection component 15 is configured to determine if a toxic chemical agent is associated with the item of mail. In a particularly preferred embodiment, the toxic chemical detection component includes a gas chromatograph mass spectrophotometer (GC/MS). A particularly preferred analytical instrument is available from ICx Technologies, Inc. (Arlington, Va.), which provides a rugged direct sampling mass spectrometer capable of multiple levels of mass spectrometry, or MS/MS. This capability provides additional levels of molecular fingerprinting, as signals of interest are isolated from the background clutter and further processed to generate highly reproducible, low noise secondary signatures for chemical identification and confirmation. This secondary process provides the necessary sensitivity and specificity to distinguish a wide range of targeted chemical compounds in complex matrices in a very rapid analysis. In one exemplary but not limiting implementation, the toxic chemical detection component includes a sampling chamber into which an item of mail is placed, while the GC/MS (or MS/MS) continuously samples the ambient air in the sampling chamber, in order to screen for toxic chemical agents. Those of ordinary skill in the art will readily recognize that in order to succeed in detecting trace levels of low-volatility chemical contaminants, particular attention must be paid to designing the sample interface between the source (i.e., the item of mail) and the sensor. Various types of sample interfaces can be beneficially employed, including heated transfer lines between the two points.
The explosive detection component is configured to determine if an explosive agent is associated with the item of mail. As indicated in
Details of a preferred automated system for swiping a sample off of an item of mail are provided below. In an exemplary, but not limiting embodiment, the explosives detector incorporated into explosive detection component 17 utilizes an amplifying fluorescence polymer (AFP) to detect trace levels of explosive materials in parts per quadrillion (ppq) quantities. Such a system is marketed under the name Fido®, and is available from ICx Technologies, Inc. (Arlington, Va.). AFP based explosive sensors can detect low femto-gram masses of TNT. This level of sensitivity far exceeds the capabilities of any other available detection system, including laboratory instruments. This technology sensitivity to plastic explosives is equivalent to or better than ion mobility spectrometer (IMS) technology (although it should be recognized that in some embodiments IMS can be used in place of AFP). Vapor phase sampling does not require physical contact with a contaminated surface. Articles contaminated with particles of explosives will produce explosive vapors as molecules of the explosive sublime from particles or desorb from surfaces. In at least one embodiment, both a vapor explosive sample and a particle explosive sample are automatically collected and analyzed for the presence of an explosive agent. In yet another embodiment, two different AFP based detectors are employed, where each detector is operating at a different temperature. This allows optimal sensitivity to different explosive compounds. Once again, a properly designed sample interface is required, and the explosives detection component can employ sample interfaces generally similar to those described above with respect to the toxic chemical detection component. Indeed, in at least one embodiment, the toxic chemical detection component and the explosive detection component share a common sample interface.
It should be noted that some explosives may be detectable using the toxic chemical detection component. For example, explosives that themselves are relatively volatile, or which include a detection taggant (i.e., a volatile chemical intentionally added to an explosive to render the explosive more readily detectable) can generally be detected using the same type of detector employed for the toxic chemical detection component (i.e., a GC/MS). Even when some explosives can be detected using the toxic chemical detection component, it is still desirable to include a separate explosive detection component (such as an AFP detector or an IMS detector), to detect less volatile explosive agents that are not as readily detectable using the toxic chemical detection component.
Puffer-based bio-threat sampling component 19 is configured to collect a bio-threat sample to be analyzed to determine if a bio-threat agent is present in the item of mail and it collects the bio-threat sample by filtering a gaseous fluid used to dislodge bio-threat particles associated with the item of mail. Note that the sample is collected automatically (such that the functions of radiation detection component 13, toxic chemical detection component 15, explosive detection component 17, and puffer-based bio-threat sampling component 19 are automated), but the analyzing step need not be automated. In at least one embodiment, a dry filter unit (DFU) is used to collect the bio-threat sample from a batch of mail (i.e., from a plurality of items of mail). Once the total batch is processed, a sample is obtained from the filter, and an analysis (such as a polymerase chain reaction (PCR) based analysis) is performed on the sample. A positive analysis will indicate that one or more items of mail in the batch are potentially contaminated with a bio-threat agent. Due to the difficulties of obtaining real time detection of bio-threats, this batch based analysis enables a system including a relatively high throughput (i.e., screening of an additional item of mail once every thirty seconds or less) to be achieved at a relatively modest cost. In a preferred but not limiting embodiment, the entire screening time for a single item of mail may be more than thirty seconds, particularly where the screening system includes a plurality of screening stations, but an item of mail will preferably pass through each screening station in about thirty seconds or less. More preferably, an item of mail will pass through each screening station in less than 10 seconds.
As indicated in
In another exemplary embodiment, schematically illustrated in
In embodiments employing relatively high flow sampling environments, the use of a virtual impactor to concentrate the sample prior to collection on a filter or in a direct-to-liquid sampler may be desirable.
Data from sizing component 35 can be used to enhance the performance of the low flow detection component. As noted above, particularly when the item of interest is present in low quantities, the sample interface is important. Adjustable sampler 39c preferably uses data from sizing component 35 to ensure that the adjustable sampler is properly positioned relative to the item of mail. For example, in at least one exemplary embodiment, the adjustable sampler is a nozzle configured to collect vapors emanating from the item of mail. Based on the dimensions determined by sizing component 35, the nozzle can then be moved closer to the item of mail, to collect a better vapor sample. The collected vapor sample can then be directed to one or more of mass spectrometer 39a and explosives detector 39b. In yet another exemplary embodiment, the adjustable sampler is a sampling substrate configured to collect a particle sample from a surface of the item of mail. Based on the dimensions determined by sizing component 35, the sampling substrate can then be placed in contact with the item of mail, to collect a particle sample. The collected particle sample can then be conveyed to one or more of mass spectrometer 39a and explosives detector 39b. Preferably, the sampling substrate is heated such that at least a portion of the collected particles vaporize, and the vapors are collected and directed to one or more of mass spectrometer 39a and explosives detector 39b. Where the system is collecting a vapor sample for analysis with GC/MS or MS/MS, it is preferable to physically move the nozzle close to the parcel, to maximize the concentration of the analyte in the sample. However, the system could be configured to just sample the air from a chamber the parcel is enclosed within. In embodiments in which the nozzle is physically moved, and the system is using Fido® (or a similar detector) to detect explosive vapors, a single nozzle could be employed. Of course, two separate nozzles could be employed, and the engineering required for the two nozzle embodiment is likely to be less complicated.
In another embodiment, adjustable sampler 39c is an automated sample arm having any one of, or combination of, thermal desorption devices or desorption ionization devices coupled thereto. The sampling device is configured to collect a particle sample from a surface of the item of mail. The adjustable sampler 39c in this embodiment is positioned near the surface of the parcel. Particles, including desorbed ions, emanating from the parcel are collected and conveyed directly to the mass spectrometer through conduits. Where the system is collecting a sample for analysis with GC/MS or MS/MS, it is preferable to physically move the sampling tube 506 close to the parcel, to maximize the concentration of the analyte in the sample.
In yet another exemplary embodiment, one or both of the low flow detection component and the high flow detection component includes a housing that defines a sampling volume. While such housings are not strictly required, they can reduce a level of vapors and particles not associated with an item of mail that are introduced into the sample.
Referring to
Returning to a discussion of the handling of the first parcel, in the vapor sampling chamber indicated in block 72, exemplary screening operations include the detection of explosives, explosive taggants and chemical warfare agents (i.e., the detection of both explosive agents and toxic chemical agents) by obtaining a vapor sample and conveying the vapor sample to the appropriate detectors (i.e., a GC/MS or MS/MS for toxic chemical agents, and an explosive detector, such as an AFP based detector (i.e., FIDO®)). If desired, radiation screening can be performed in the vapor sampling chamber (using a suitable radiation detector, such as the radiation detectors discussed above). In at least one exemplary but not limiting embodiment, an adjustable sample nozzle is positioned close (i.e., within several millimeters) to the parcel based on previously determined parcel dimensions, to collect a quality vapor sample. In another embodiment, a thermal desorption device and/or a desorption ionization device is positioned close, e.g. within several millimeters, to the parcel. As discussed above, the sampling device includes the appropriate devices to carry out one or more of the following sampling techniques: thermal desorption including pulsed lasers and flash lamps; and desorption ionization techniques including DESI; AP-MALDI; DART; and LTP. Since each parcel has a unique RFID tag, the test data from each sensor (i.e., radiation detector, toxic chemical detectors, and explosive detector) is stored in a database, which associates the data collected for each parcel with that parcel's RFID tag.
After samples have been acquired in the vapor sampling chamber, the parcel is then advanced to the particulate sampling chamber as indicated in block 74, where the presence of the parcel is detected (via an optical switch in an exemplary but not limiting implementation), and the conveyor belt is stopped once again. In this particulate sampling chamber, exemplary screening operations include the detection of explosives, explosive taggants and chemical warfare agents (i.e., the detection of both explosive agents and toxic chemical agents) by obtaining particle samples and conveying the particle sample to the appropriate detectors (i.e., a GC/MS or MS/MS for toxic chemical agents, and an explosive detector, such as an AFP based detector (i.e., Fido®)). In an exemplary, but not limiting embodiment, a sampling substrate is positioned (based on a previously determined parcel size) so as to contact the parcel and to collect a particle sample. The collected particle sample can then be conveyed via a robotic positioning element with a gripper holding the sampling substrate to one or more of mass spectrometer 39a and explosives detector 39b (see
The parcel is then advanced to the X-ray sampling chamber (block 76), where for example, an image is taken of the parcel and an operator visually reviews the image for the presence of an explosive agent. Since each parcel has a unique RFID tag, the image from the sensor is stored in a database which associates the image to each parcel.
With respect to screening for radioactivity, as noted above a preferred detector will be capable of indicating both the presence of radioactivity, and the specific isotope emitting the radiation. If a simpler detector is employed (i.e., a detector capable only of identifying the presence of radioactivity, but not the source of the radiation), a secondary screening operation can be manually performed on the parcel to identify the radioisotope source, utilizing hand held radiation identification devices, or taking a sample for analysis using non-portable detectors, so that a definitive identification of the source of the radiation can be made. The parcel is then advanced to the particulate sampling chamber as shown in block 76 via an optical switch, for example, that stops and starts the conveyor belt.
a is a functional block diagram of a mail screening system 71, which differs from mail screening system 31 of
In an alternative embodiment shown in
a illustrates various exemplary embodiments 130 of automated sample arms. Each such embodiment is configured to be employed in a screening system where the item of mail (a parcel in an exemplary embodiment, although it should be recognized that a swipe sample could be to taken of the upper surface of a letter or flat) is moved through the system on a conveyor (such as a conveyor belt or a roller conveyor). A sizing component (such as a light curtain) is used to determine at least one dimension of the item of mail (such as its height), so that the automated sample arm can be positioned properly relative to the item of mail, so that the sample substrate can be wiped across a surface of the item of mail. Each of the embodiments 130 includes a frame configured to support the automated sample arm. In the illustrated embodiments, the conveyor component passes through the frame, although it should be recognized that such a configuration is simply exemplary, and not limiting on the actual structure employed. Where the conveyor component passes through the frame, the frame must be large enough to accommodate the largest parcel size likely to be encountered.
An embodiment 130a is configured to move a sample substrate 87 along a single linear axis (indicated by an arrow 89a), via translation means 89. It should be recognized that translation means 89 can be implemented in many ways. Exemplary, but not limiting translation means include hydraulics, pneumatics, worm drives, screw drives, chain drives, and combinations of racks gears and pinions. Translation means 89 uses data from a sizing component (such as a light curtain) to position sampling substrate 87 so that the sampling substrate swipes (or scans, e.g. contactless) a line across a top surface of parcel 91 as conveyor 32 moves parcel 91 along an axis indicated by an arrow 83a. In other words, translation means 89 adjusts a height of the sampling substrate relative to a height of the parcel. It should be noted that the sample substrate could be replaced with a sample nozzle or a thermal desorption and/or desorption ionization sampling device 87a, shown in
An embodiment 130b is configured to move sample substrate 87 along two different linear axes (indicated by arrow 89a and an arrow 93a), via translation means 89 and a translation means 93. Again, each translation means can be implemented using many different structures. As noted above, translation means 89 uses data from a sizing component (such as a light curtain) to position sampling substrate 87 so that the sample substrate swipes (or scans) a line across a top surface of parcel 91 as conveyor 32 moves parcel 91 along an axis indicated by an arrow 83b. Translation means 93 can be used to move the sample substrate to a different position on the upper surface of the parcel. The combined motions of the conveyor and translation means 93 enable diagonal scans or swipes to be achieved. If translation means 93 is moving rapidly relative to the motion of the parcel caused by conveyor 32 (the parcel motion is indicated by an arrow 83b), then a plurality of diagonal scans or swipes across the surface of the parcel can be achieved. To avoid allowing translation means 93 to move the sample substrate beyond the surface of the parcel during scanning/swiping, translation means 93 can use data from a sizing component (such as a light curtain). Note that navigation of the top of the parcel by the sampling substrate requires coordination of motion of the automated sample arm and the conveyor.
An embodiment 130c is configured to move sample substrate 87 along three different linear axes (indicated by arrow 89a, arrow 93a, and an arrow 95a), via translation means 89, translation means 93, and one or more translation means 95. Again, each translation means can be implemented using many different structures. Translation means 89 and 93 function as described above. Translation means 95 can be used to move the sample substrate to a different position on the upper surface of the parcel. Note that translation means 95 enables motion in a direction orthogonal to the motion enabled by translation means 93. With parcel 91 in a static position, the combined motions of translation means 93 and 95 enable diagonal scans or swipes, or raster scanning/swiping to be achieved (even spiral scanning can be achieved if desired). If translation means 93 is moving rapidly relative to the motion of translation means 95 (or vice versa), then a plurality of diagonal scans or swipes across the surface of the parcel can be achieved. To avoid allowing translation means 95 to move the sample substrate beyond the surface of the parcel during scanning/swiping, translation means 95 can use data from a sizing component (such as a light curtain). Note that navigation of the top of the parcel by the sampling substrate can be achieved independent of the motion of the conveyor.
An embodiment 130d is configured to move sample substrate 87 along three different linear axes (indicated by arrow 89a, arrow 93a, and arrow 95a) and two rotational axes, via translation means 89, translation means 93, (one or more of) translation means 95, and rotational means 97 and 99. Each translation means and rotational means can be implemented using many different structures. Translation means 89, 93 and 95 function as described above. Rotational means 97 can be coordinated with translation means 89 and 95 to enable sides 91a and 91b to be scanned/swiped. Rotational means 99 can be coordinated with translation means 89 and 93 to enable a side 91c to be scanned/swiped. If an additional translation means 93 is added to portion 101 of the frame, then rotational means 99 can be coordinated with translation means 89 and additional translation means 93 to enable a side 91d to be scanned/swiped. Note that navigation of the top and sides of the parcel by the sampling substrate can be achieved independent of the motion of the conveyor. Further note that the dimensions of the frame have been increased to accommodate the degrees of freedom required by the rotational means.
With respect to
Parcel dimension screening station 24 can be implemented using a light curtain, which determines the dimensions of the parcel, and the parcel's relative position on the conveyor. As discussed above (particularly with respect to
In at least one embodiment, automated sample arm screening station 36 includes means to regenerate the sample substrate so that it can be re-used. In some embodiments, a plurality of substrates are provided initially, and after a sample is collected and a portion is volatilized, the used sample substrate is moved to a regenerator (generally a heated chamber that can heat the sampling substrate for a period of time likely to be sufficient to remove substantially all traces of the sample). A fresh sample substrate is used to collect the next sample. After the initial sample substrates have all been used, a regenerated sample substrate is employed. The number of sample substrates required is a function of the speed at which samples are collected and the time required to regenerate the sample substrates (faster sampling rates and slower regeneration times will require larger numbers of sample substrates). If the regenerated sample substrate needs to be cooled before re-use, either more sample substrate will need to be provided initially, or cooling means must be provided. Empirical studies indicate that regeneration is effective for up to 100 samples. Alternatively, a new sample substrate can be used for each sample.
Combined toxic chemical and bio-warfare screening station 26 includes a housing having an entry and exit. The interior of the housing is separated from the ambient atmosphere by air curtains 38 (see
The parcel is then moved through the X-ray imaging screening station. As discussed in detail above, a trained operator can be used to review the image for each parcel, the images can be screened automatically by an expert system, or the images can be stored and reviewed only if the explosives detector indicates the presence of an explosive agent.
In
a is a flow chart illustrating exemplary method steps for using screening system 34 (
As shown in
It should be appreciated that the thermal desorption and/or desorption ionization surface sampling techniques, e.g. the ionization and thermal desorption sampling techniques described above are not limited to detection of explosive agents. The applicable thermal desorption and/or desorption ionization surface sampling techniques can be configured and used for sampling for chemical and biological agents.
Then the parcel moves to the next sampling station (combined toxic and BW screening station 26), and a vapor sample is collected (as indicated by a step 106), and analyzed by a mass spectrometer to determine if a toxic chemical agent is present (as indicated in a step 108). While the parcel is in the combined screening station, a bio-threat sample is acquired by the DFU (note this step may involve the use of a puffer to drive particles off of the parcel), as indicated in a step 110. The parcel in then moved to the X-ray screening station, and an X-ray image is taken, as indicated by a step 112.
In a decision step 114, a determination is made as to whether the radiation detector, the explosive detector, the toxic chemical detector or the X-ray image has identified a threat agent. If so, secondary screening can be initiated if desired, as indicated in step 126. Such secondary screening can involve the collection and analysis of another sample from the parcel, analysis of a collected sample using an additional detection technology, or identification of the source of radiation detection by a radiation detector that simply responds to the presence of radiation, without identifying the source. Based on the type of threat detected, appropriate responses can be executed.
If no threat is detected, then in decision step 116 a determination is made as to whether each item of mail (or parcel) in a batch of mail has been screened. If not, then the screening process is repeated for the next parcel, as indicated in a step 118. If each parcel in a batch has been screened, then the DFU sample is analyzed for bio-agents/bio-warfare agents, as indicated in a step 120. If in a decision step 122 it is determined that no BW agent is present, the batch of parcels is released for delivery, as indicated in a step 124. If in a decision step 122 it is determined that a BW agent is present, secondary screening on the batch of parcels is performed (as indicated in step 126), in order to identify one or more parcels associated with the detected BW threat. Appropriate responses can then be implemented to counter the threat.
It should be recognized that the steps disclosed with respect to
Where specific dimensions are referred to above, it should be recognized that the disclosure is merely intended to be exemplary, and it is further intended to be broadly interpreted so as to encompass variations to such specifically identified parameters. Thus, such parameters should not be considered to be limiting, unless limitations are specifically recited in the claims that follow.
Other embodiments of the current invention will be apparent to those skilled in the art from a consideration of this specification or practice of the invention disclosed herein. Thus, the foregoing specification is considered merely exemplary of the current invention with the true scope thereof being defined by the following claims. Thus, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned and alluded to, as well as those which are inherent therein.
This application is a continuation in part application of U.S. patent application Ser. No. 12/118,594, filed on May 9, 2008 which claims the benefit of provisional application, Ser. No. 60/916,972, filed on May 9, 2007.
| Number | Date | Country | |
|---|---|---|---|
| 60916972 | May 2007 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12118594 | May 2008 | US |
| Child | 13285672 | US |
