WO2014045061A1

WO2014045061A1 - Contamination reduction apparatus

Info

Publication number: WO2014045061A1
Application number: PCT/GB2013/052480
Authority: WO
Inventors: Stephen Taylor
Original assignee: Smiths Detection-Watford Limited
Priority date: 2012-09-24
Filing date: 2013-09-23
Publication date: 2014-03-27

Abstract

An apparatus, such as an IMS detector, includes a chamber having a region configured to receive a vapour including a target material. Alight source is operable to emit pulses of light within the region. The pulses of light are configured to inhibit the formation of particles of contaminants within the vapour and/or to cause the target material to be released from the surface of the particles of contaminant when formed. In example implementations, the light source may comprise a flash lamp.

Description

Contamination Reduction Apparatus

BACKGROUND

[0001] Ion mobility spectrometry (IMS) refers to an analytical technique that can be used to separate and identify ionized material, such as molecules and atoms. Ionized material can be identified in the gas phase based on mobility in a carrier buffer gas. Thus, an ion mobility spectrometer (IMS) can identify material from a sample of interest by ionizing the material and measuring the time it takes the resulting ions to reach a detector. An ion's time of flight is associated with its ion mobility, which relates to the mass and geometry of the material that was ionized. The output of an IMS detector can be visually represented as a spectrum of peak height versus drift time. In some instances, IMS detection is performed at an elevated temperature (e.g., above one hundred degrees Celsius (100°C)). In other instances, IMS detection can be performed without heating. IMS detection can be used for military and security applications, e.g., to detect drugs, explosives, and so forth. IMS detection can also be used in laboratory analytical applications, and with complementary detection techniques such as mass spectrometry, liquid chromatography, and so forth.

SUMMARY

[0002] Systems and techniques are disclosed to limit the formation of particles of contaminant within the vapour. In one or more implementations, the systems and techniques may be implemented in an apparatus, such as an IMS detector, that includes a chamber having a region configured to receive a vapour including a target material. A light source is operable to emit pulses of light within the region. The pulses of light are configured to inhibit the formation of particles of contaminants within the vapour and/or to cause the target material to be released from the surface of the particles of contaminant when formed. In example implementations, the light source may comprise a flash lamp.

[0003] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features 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.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identify the figure in which the reference number first appears. The use of the same reference number in different instances in the description and the figures may indicate similar or identical items.

[0005] FIG. 1 is a diagrammatic illustration of a system including an IMS detector employing a light source in accordance with an example implementation of the present disclosure.

[0006] FIG. 2 is a diagrammatic illustration of a system including a controller operatively coupled with an FMS detector, where the controller can be used to control the operation of the light source in accordance with an example implementation of the present disclosure.

DETAILED DESCRD7TION

[0007] IMS detection systems may employ thermal desorption of solid samples into a detector, such as an IMS detector, which is not heated. The samples may be those acquired using a swab, as typically used for explosives and narcotics particulate detection. The swab is heated to thermally desorb the vapour from the sample, which may be a mixture of contaminants (e.g., dirt, inorganic components such as soil particles, organic components, and so forth) and target materials such as target explosives or narcotics material. Desorption of air bound samples into the detector may also be employed using a sample probe.

[0008] High video microscopy testing has shown that when typical explosives detector swabs are heated, particles are flung off the swab surface, probably in addition to the vapour being released. When significant amounts of contaminants and trace levels of target materials are simultaneously desorbed from a swab, the usual response of the IMS detector to the contaminants is much diminished in amplitude. For example, when contaminants at typical ambient levels are thermally desorbed, the contaminants may form a super-saturated cloud of contaminant vapour and small particles, which may condense into more and larger particles. At the same time, target material vapour within the cloud may condense onto the particles. This process extracts target material vapour from the vapour phase, and leaves less target material available to be detected by the vapour phase detector (e.g. the Ion Mobility Spectrometer (IMS)).

[0009] The degree of this adverse effect is a function of the amount of contaminant, the vapour pressure of the target material, and so forth. As the amount of contaminant is increased, the number density of contaminant particles formed is likely to rise and the rate at which the particles form and expand will increase. When the target material has a low vapour pressure, the target material vapour is more likely to adhere to the particles and remain adhered. When the target material has a high vapour pressure, the target material vapour is less likely to adhere to the particles and much less of it will be trapped on the particles.

[0010] To reduce the effect of contaminant particle formation, the detector may be heated so that the contaminant vapour is not at a super-saturated concentration. The high air temperature in the detector allows for greater solubility of the contaminant vapour in the air. Thus, the contaminants would not precipitate out of the vapour. In applications such as portable detection system applications, heating the detector to the temperature required to prevent contaminant particle formation may be undesirable. For example, such heating may necessitate that the detector be a high-temperature-capable detector, with limitations on materials selection. Moreover, for a handheld device, the power used to heat the detector requires the use of large batteries.

[0011] Systems and techniques are disclosed to limit the formation of particles of contaminant within the vapour. In one or more implementations, the systems and techniques may be implemented in an apparatus, such as an FMS detector, that includes a chamber having an ionization region configured to receive a vapour including a target material for ionization of the target material. A light source is disposed in the ionization region. The light source is operable to emit pulses of light within the region. The pulses of light are configured to inhibit the formation of particles of contaminants within the vapour and/or to cause the target material to be released from the surface of the particles of contaminant when formed. In example implementations, the light source may comprise a flash lamp. However, it is contemplated that the light source may also comprise a continuous (non-flash) light source, a laser light source, and so forth

[0012] FIG. 1 illustrates a spectrometer system, such as an ion mobility spectrometer (IMS) system 100. Although IMS detection techniques are described herein, it should be noted that a variety of different spectrometers can benefit from the structures, techniques, and approaches of the present disclosure. It is the intention of this disclosure to encompass and include such changes.

[0013] IMS systems 100 can include spectrometry equipment that employs unheated (e.g., surrounding (ambient or room) temperature) detection techniques. For example, an IMS system 100 can be configured as a lightweight explosive detector. However, it should be noted that an explosive detector is provided by way of example only and is not meant to be restrictive of the present disclosure. Thus, techniques of the present disclosure may be used with other spectrometry configurations. For example, an IMS system 100 can be configured as a chemical detector. An IMS system 100 can include a detector device, such as an IMS detector 102 having a sample receiving port for introducing material from a sample of interest to an ionization region/chamber. For example, the FMS detector 102 can have an inlet 104 where air to be sampled is admitted to the IMS detector 102. In some implementations, the IMS detector 102 can have another device such as a gas chromatograph (not shown) connected in line with the IMS inlet 104. [0014] The inlet 104 can employ a variety of sample introduction approaches. In some instances, a flow of air can be used. In other instances, IMS systems 100 can use a variety of fluids and/or gases to draw material into the inlet 104. Approaches for drawing material through the inlet 104 include the use of fans, pressurized gases, a vacuum created by a drift gas flowing through a drift region/chamber, and so forth. For example, the IMS detector 102 can be connected to a sampling line, where air from the surrounding environment (e.g., room air) is drawn into the sampling line using a fan. IMS systems 100 can operate at substantially ambient pressure, although a stream of air or other fluid can be used to introduce sample material into an ionization region. In other instances, IMS systems 100 can operate at lower pressures (i.e., pressures less than ambient pressure). Further, FMS systems 100 can include other components to furnish introduction of material from a sample source. For example, a desorber, such as a heater, can be included with an FMS system 100 to cause at least a portion of a sample to vaporize (e.g., enter its gas phase) so the sample portion can be drawn into the inlet 104. For instance, a sample probe, a swab, a wipe, or the like, can be used to obtain a sample of interest from a surface. The sample probe can then be used to deliver the sample to the inlet 104 of an FMS system 100. IMS systems 100 can also include a pre-concentrator to concentrate or cause a bolus of material to enter an ionization region.

[0015] A portion of a sample can be drawn through a small aperture inlet (e.g., a pinhole) into the FMS detector 102 using, for example, a diaphragm in fluid communication with an interior volume of the IMS detector 102. For instance, when the internal pressure in the interior volume is reduced by movement of the diaphragm, a portion of the sample is transferred from the inlet 104 into the FMS detector 102 through the pinhole. After passing through the pinhole, the sample portion enters a chamber comprising an ionization region 106 where the sample is ionized using an ionization source, such as a corona discharge ionizer (e.g., having a corona discharge point 108). In some instances, the corona discharge point 108 can ionize material from a sample of interest in multiple steps. For example, the corona discharge point 108 can generate a corona that ionizes gases in the ionization region 106 that are subsequently used to ionize the material of interest. Example gases include, but are not necessarily limited to: nitrogen, water vapor, gases included in air, and so forth.

[0016] In implementations, the IMS detector 102 can operate in positive mode, negative mode, switch between positive and negative mode, and so forth. For example, in positive mode the corona discharge point 108 can generate positive ions from a sample of interest, while in negative mode the corona discharge point 108 can generate negative ions. Operation of the EVIS detector 102 in positive mode, negative mode, or switching between positive and negative mode can depend on implementation preferences, a predicted sample type (e.g., explosive, narcotic, toxic industrial chemicals), and so forth. Further, the corona discharge point 108 can be pulsed periodically (e.g., based upon sample introduction, gate opening, the occurrence of an event, and so on).

[0017] The sample ions can then be directed toward a gating grid using an electric field. The gating grid can be opened momentarily to allow small clusters of sample ions to enter a drift region. For example, the IMS detector 102 can include an electronic shutter or gate 1 10 at the inlet end of a drift region 1 12. In implementations, the gate 110 controls entrance of ions to the drift region 112. For example, the gate 110 can include a mesh of wires to which an electrical potential difference is applied or removed. The drift region 1 12 has electrodes 1 14 (e.g., focusing rings) spaced along its length for applying an electric field to draw ions along the drift region 112 and/or to direct the ions toward a detector disposed generally opposite the gate 110 in the drift region 1 12. For example, the drift region 1 12, including the electrodes 1 14, can apply a substantially uniform field in the drift region 1 12. The sample ions can be collected at a collector electrode, which can be connected to analysis instrumentation for analyzing the flight times of the various sample ions. For instance, a collector plate at the far end of the drift region 1 12 can collect ions that pass along the drift region 1 12.

[0018] The drift region 1 12 can be used to separate ions admitted to the drift region 1 12 based on the individual ions' ion mobility. Ion mobility is determined by the charge on an ion, an ion's mass, geometry, and so forth. In this manner, IMS systems 100 can separate ions based on time of flight. The drift region 1 12 can have a substantially uniform electrical field that extends from the gate 110 to a collector. The collector can be a collector plate (e.g., a Faraday plate) that detects ions based on their charge as they contact the collector plate. In implementations, a drift gas can be supplied through the drift region 1 12 in a direction generally opposite the ions' path of travel to the collector plate. For example, the drift gas can flow from adjacent the collector plate toward the gate 1 10. Example drift gases include, but are not necessarily limited to: nitrogen, helium, air, air that is re-circulated (e.g., air that is cleaned and/or dried) and so forth. For example, a pump can be used to circulate air along the drift region 1 12 against the direction of flow of ions. The air can be dried and cleaned using, for instance, a molecular sieve pack.

[0019] In implementations, the EVIS detector 102 can include a variety of components to promote identification of a material of interest. For example, the EVIS detector 102 can include one or more cells containing a calibrant and/or a dopant component. Calibrant can be used to calibrate the measurement of ion mobility. Dopant can be used to prohibit the ionization of interferant ions. Dopant can also be combined with a sample material and ionized to form an ion that can be more effectively detected than an ion that corresponds to the sample material alone. Dopant can be provided to one or more of the inlet 104, the ionization region 106 and/or the drift region 1 12. The EVIS detector 102 can be configured to provide dopant to different locations, possibly at different times during operation of the EVIS detector 102. The IMS detector 102 can be configured to coordinate dopant delivery with operation of other components of an IMS system 100.

[0020] A controller 150 can detect the change in charge on the collector plate as ions reach it. Thus, the controller 150 can identify materials from their corresponding ions. In implementations, the controller 150 can also be used to control opening of the gate 110 to produce a spectrum of time of flight of the different ions along the drift region 1 12. For example, the controller 150 can be used to control voltages applied to the gate 110. Operation of the gate 110 can be controlled to occur periodically, upon the occurrence of an event, and so forth. For example, the controller 150 can adjust how long the gate 110 is open and/or closed based upon the occurrence of an event (e.g., corona discharge), periodically, and so forth. Further, the controller 150 can switch the electrical potential applied to the gate 110 based upon the mode of the ionization source (e.g., whether the IMS detector 102 is in positive or negative mode). In some instances, the controller 150 can be configured to detect the presence of explosives and/or chemical agents and provide a warning or indication of such agents on an indicator 158.

[0021] As noted, the IMS system 100 may employ thermal desorption of solid samples into the IMS detector, which is not heated. The samples may be those acquired using a swab, as typically used for explosives and narcotics particulate detection. The swab is heated to thermally desorb the vapour from the sample, which may be a mixture of contaminants (e.g., dirt, inorganic components such as soil particles, organic components, and so forth) and target materials such as target explosives or narcotics material.

[0022] The FMS system 100 includes a light source 1 16 to heat the contaminant particles to limit the rate at which they form and/or to release target material vapour that may have adhered to the particle surfaces. In implementations, light from the light source 116 may further limit the precipitation of the target material vapour alone, in the absence of contaminant vapour, and render the detector more sensitive to the target material. As shown in FIG. 1 , the light source may be disposed within the ionization region 106 of the IMS system 100. However, it is contemplated that a light source 1 16 may be provided within other regions of the FMS system 100.

[0023] In implementations, the light source 1 16 may comprise a flash lamp. The flash lamp may be configured so that the light power levels impinging upon the contaminant particles, which may be micron and sub-micron sized particles, is sufficiently high to be effective in raising the particle temperature but not sufficiently high to cause heating of the ionization region 106. The contaminant particles are in good thermal contact with the air in the ionization region 106, such that heat absorbed by contaminant particles from relatively low power levels of light is dissipated sufficiently fast that the temperature rise in the region is negligible. However, when the light power is many orders of magnitude greater, the heat will not dissipate sufficiently fast, and the particle will rise in temperature (e.g., in the order of tens, or even a few hundred degrees Celsius). The amount of heating is dependent upon the particle size, as well as the light power of the light source 116 (e.g., the flash lamp).

[0024] The flash lamp may be operable by accumulating electrical energy within a capacitor over a period of time (e.g., a few milliseconds), and then discharging this electrical energy in a very short period, through the flash lamp. In implementations, the flash duration of the flash lamp is approximately ten microseconds (ΙΟμβ). However, it will be appreciated that flash duration of longer or shorter than ten microseconds (ΙΟμβ) are possible.

[0025] In other implementations, it is contemplated that the light source 1 16 may comprise a continuous light source, a laser, a scanning laser having a gimbal assembly configured to raster the light beam from the laser through the ionization region 106 to uniformly heat contaminant particles within the region 106, a laser diode assembly, and so forth.

[0026] In implementations, an IMS system 100, including some or all of its components, can operate under computer control. For example, a processor can be included with or in an IMS system 100 to control the components and functions of IMS systems 100 described herein using software, firmware, hardware (e.g., fixed logic circuitry), manual processing, or a combination thereof. The terms "controller" "functionality," "service," and "logic" as used herein generally represent software, firmware, hardware, or a combination of software, firmware, or hardware in conjunction with controlling the IMS systems 100. In the case of a software implementation, the module, functionality, or logic represents program code that performs specified tasks when executed on a processor (e.g., CPU or CPUs). The program code may be stored in one or more computer-readable memory devices (e.g., internal memory and/or one or more tangible media), and so on. The structures, functions, approaches, and techniques described herein can be implemented on a variety of commercial computing platforms having a variety of processors.

[0027] For example, as illustrated in FIG. 2, the IMS detector 102 may be coupled with the controller 150 for controlling the IMS detector 102. The controller 150 may include a processing system 152, a communications module 154, and memory 156. The processing system 152 provides processing functionality for the controller 150, and may include any number of processors, micro-controllers, or other processing systems and resident or external memory for storing data and other information accessed or generated by the controller 150. The processing system 152 may execute one or more software programs, which implement techniques described herein. The processing system 152 is not limited by the materials from which it is formed or the processing mechanisms employed therein, and as such, may be implemented via semiconductor(s) and/or transistors (e.g., using electronic integrated circuit (IC) components), and so forth. The communications module 154 is operatively configured to communicate with components of the FMS detector 102. The communications module 154 is also communicatively coupled with the processing system 152 (e.g., for communicating inputs from the IMS detector 102 to the processing system 152). The communications module 154 and/or the processing system 152 can also be configured to communicate with a variety of different networks, including, but not necessarily limited to: the Internet, a cellular telephone network, a local area network (LAN), a wide area network (WAN), a wireless network, a public telephone network, an intranet, and so on.

[0028] The memory 156 is an example of tangible computer-readable media that provides storage functionality to store various data associated with operation of the controller 150, such as software programs and/or code segments, or other data to instruct the processing system 152 and possibly other components of the controller 150 to perform the steps described herein. Thus, the memory 156 can store data, such as a program of instructions for operating the IMS system 100 (including its components), spectral data, and so on. Although a single memory 156 is shown, a wide variety of types and combinations of memory (e.g., tangible, non-transitory memory) may be employed. The memory 156 may be integral with the processing system 152, may comprise standalone memory, or may be a combination of both.

[0029] The memory 156 may include, but is not necessarily limited to: removable and non-removable memory components, such as Random Access Memory (RAM), Readonly Memory (ROM), Flash memory (e.g., a Secure Digital (SD) memory card, a mini- SD memory card, and/or a micro-SD memory card), magnetic memory, optical memory, Universal Serial Bus (USB) memory devices, hard disk memory, external memory, and other types of computer-readable storage media. In implementations, the IMS detector 102 and/or memory 156 may include removable Integrated Circuit Card (ICC) memory, such as memory provided by a Subscriber Identity Module (SIM) card, a Universal Subscriber Identity Module (USIM) card, a Universal Integrated Circuit Card (UICC), and so on.

[0030] In implementations, a variety of analytical devices can make use of the structures, techniques, approaches, and so on described herein. Thus, although IMS systems 100 are described herein, a variety of analytical instruments may make use of the described techniques, approaches, structures, and so on. These devices may be configured with limited functionality (e.g., thin devices) or with robust functionality (e.g., thick devices). Thus, a device's functionality may relate to the device's software or hardware resources, e.g., processing power, memory (e.g., data storage capability), analytical ability, and so on.

An apparatus, such as an IMS detector, includes a chamber having a region configured to receive a vapour including a target material. A light source is operable to emit pulses of light within the region. The pulses of light are configured to inhibit the formation of particles of contaminants within the vapour and/or to cause the target material to be released from the surface of the particles of contaminant when formed. In example implementations, the light source may comprise a flash lamp.

[0031] Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Although various configurations are discussed the apparatus, systems, subsystems, components and so forth can be constructed in a variety of ways without departing from this disclosure. Rather, the specific features and acts are disclosed as example forms of implementing the claims.

Claims

CLAIMS What is claimed is:

1. An Ion Mobility Spectrometry (IMS) system comprising:

a chamber having an ionization region configured to receive a vapour including a target material for ionization of the target material; and

a light source disposed within the ionization region, the light source operable to emit a pulse of light within the ionization region configured to at least one of inhibit the formation of particles of a contaminant within the vapour or to cause the target material to be released from the surface of the particles of contaminant when formed.

2. The Ion Mobility Spectrometry (IMS) system as recited in claim 1, wherein the wherein the light source comprises a flash lamp.

3. The Ion Mobility Spectrometry (IMS) system as recited in claim 1 or 2, wherein the flash lamp is configured to emit a pulse of light that is about ten microseconds (ΙΟμβ) in duration.

4. The Ion Mobility Spectrometry (IMS) system as recited in claim 1, 2 or 3, wherein the light source comprises a laser.

5. The Ion Mobility Spectrometry (IMS) system as recited in claim 1, 2 or 3, wherein the pulse of light is configured to raise the temperature of the particle.

6. The Ion Mobility Spectrometry (IMS) system as recited in claim 5, wherein the pulse of light is configured to not substantially raise the temperature of the chamber.

7. The Ion Mobility Spectrometry (IMS) system as recited in claim 6, wherein the target material is thermally desorbed from a solid sample.

8. The Ion Mobility Spectrometry (IMS) system as recited in claim 7, wherein the solid sample comprises a swab.

9. An apparatus comprising:

a chamber having a region configured to receive a vapour including a target material; and

a light source operable to emit a pulse of light within the region, the pulse of light configured to at least one of inhibit the formation of particles of a contaminant within the vapour or to cause the target material to be released from the surface of the particles of contaminant when formed.

10. The apparatus as recited in claim 9, wherein the light source comprises a flash lamp.

11. The apparatus as recited in claim 10, wherein the flash lamp is configured to emit a pulse of light that is about ten microseconds (ΙΟμβ) in duration.

12. The apparatus as recited in claim 9, 10, 11 wherein the light source comprises a laser.

13. The apparatus as recited in any of claims 9 to 12, wherein the pulse of light is configured to raise the temperature of the particle.

14. The apparatus as recited in claim 13, wherein the pulse of light is configured to not substantially raise the temperature of the chamber.

15. The apparatus as recited in claim any of claims 9 to 14, wherein the region comprises the ionization region of an Ion Mobility Spectrometry (IMS) detector.