Improving the Sensitivity and Resolution of Miniature Ion Mobility Spectrometers with a Capacitive Trans Impedance Amplifier

Persistent Link:
http://hdl.handle.net/10150/195646
Title:
Improving the Sensitivity and Resolution of Miniature Ion Mobility Spectrometers with a Capacitive Trans Impedance Amplifier
Author:
Denson, Stephen Charles
Issue Date:
2005
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The selectivity and sensitivity of ion mobility spectrometry (IMS) to explosives was first demonstrated by Karasek in 1974.1 Airport security has always been a concern in the United States, especially since September 11th, 2001, and as a result IMS is commonly used to screen airline passengers and their luggage at all major airports. Portable IMS systems are now widely available for a variety of applications, but as the overall size of the IMS instrumentation decreases, the sensitivity typically decreases as well. A new ion detector read out technology, a capacitive trans-impedance amplifier (CTIA), coupled to a traditional Faraday plate has shown increased sensitivity over a Faraday plate read by a conventional current to voltage converter when used in mass spectrometry. Sandia National Laboratories sponsored a project to determine whether the CTIA technology could be coupled to an IMS, and to determine the potential increase in sensitivity that could be provided to a miniature IMS equipped with the new read out technology.Sandia first provided a full size IMS, a Phemto-Chem PCP-110, which was modified to support the first generation of CTIA (CTIA1). The CTIA1 was coupled to the IMS and was successfully used to detect explosives. Next, Sandia provided miniature IMS drift tubes, but incompatibilities necessitated the design of new miniature systems. At first, only the drift tube itself was redesigned, but eventually a complete miniature IMS, including the ionizer, circuitry, and read out, was designed and built. During the design phase a new ion-beam shutter capable of increased resolution was also implemented. The second generation of CTIA was coupled to a custom drift tube and the system demonstrated increased resolution and drastically increased sensitivity to the common explosives TNT and RDX when compared to the sensitivity of the system provided by Sandia. A custom miniature drift tube coupled to a CTIA will be placed into the peripheral equipment for Sandia's MicroHound II instrumentation to provide a portable IMS with sensitivity equal to or better than bench top IMS systems.
Type:
text; Electronic Dissertation
Keywords:
ion mobility; capacitive transimpedance amplifier
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Denton, M. Bonner
Committee Chair:
Denton, M. Bonner

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleImproving the Sensitivity and Resolution of Miniature Ion Mobility Spectrometers with a Capacitive Trans Impedance Amplifieren_US
dc.creatorDenson, Stephen Charlesen_US
dc.contributor.authorDenson, Stephen Charlesen_US
dc.date.issued2005en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe selectivity and sensitivity of ion mobility spectrometry (IMS) to explosives was first demonstrated by Karasek in 1974.1 Airport security has always been a concern in the United States, especially since September 11th, 2001, and as a result IMS is commonly used to screen airline passengers and their luggage at all major airports. Portable IMS systems are now widely available for a variety of applications, but as the overall size of the IMS instrumentation decreases, the sensitivity typically decreases as well. A new ion detector read out technology, a capacitive trans-impedance amplifier (CTIA), coupled to a traditional Faraday plate has shown increased sensitivity over a Faraday plate read by a conventional current to voltage converter when used in mass spectrometry. Sandia National Laboratories sponsored a project to determine whether the CTIA technology could be coupled to an IMS, and to determine the potential increase in sensitivity that could be provided to a miniature IMS equipped with the new read out technology.Sandia first provided a full size IMS, a Phemto-Chem PCP-110, which was modified to support the first generation of CTIA (CTIA1). The CTIA1 was coupled to the IMS and was successfully used to detect explosives. Next, Sandia provided miniature IMS drift tubes, but incompatibilities necessitated the design of new miniature systems. At first, only the drift tube itself was redesigned, but eventually a complete miniature IMS, including the ionizer, circuitry, and read out, was designed and built. During the design phase a new ion-beam shutter capable of increased resolution was also implemented. The second generation of CTIA was coupled to a custom drift tube and the system demonstrated increased resolution and drastically increased sensitivity to the common explosives TNT and RDX when compared to the sensitivity of the system provided by Sandia. A custom miniature drift tube coupled to a CTIA will be placed into the peripheral equipment for Sandia's MicroHound II instrumentation to provide a portable IMS with sensitivity equal to or better than bench top IMS systems.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjection mobilityen_US
dc.subjectcapacitive transimpedance amplifieren_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorDenton, M. Bonneren_US
dc.contributor.chairDenton, M. Bonneren_US
dc.contributor.committeememberWysocki, Vickien_US
dc.contributor.committeememberEnemark, Johnen_US
dc.contributor.committeememberMiller, Walteren_US
dc.contributor.committeememberSchram, Karlen_US
dc.identifier.proquest1314en_US
dc.identifier.oclc137354981en_US
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