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A. I. Akinwande - One of the best experts on this subject based on the ideXlab platform.

  • A Microionizer for Portable Mass Spectrometers Using Double-Gated Isolated Vertically Aligned Carbon Nanofiber Arrays
    IEEE Transactions on Electron Devices, 2011
    Co-Authors: L.-y. Chen, L. F. Velasquez-garcia, X. Wang, A. I. Akinwande
    Abstract:

    We report a gas ionizer based on arrays of microfabricated double-gated isolated vertically aligned carbon nanofibers (VA-CNFs) for application in low-power portable Mass Spectrometers. Field-emitted electrons from VA-CNFs are accelerated to high energy and subsequently collide with neutral gas molecules, leading to ionization/fragmentation of the molecules. Double-gated field-emitter arrays with isolated VA-CNF tips were fabricated using a photoresist planarization technique. Two types of devices were fabricated and characterized. The first type of device has the emitter tip in the same plane as the extraction gate, and the second type of device has the emitter tip 900 nm below the extraction gate. All devices were made using a process that results in gate and focus diameters of 1.7 and 4.2 μm, respectively. When operated as a field-emitted electron impact ionizer (EII), for the same ion current, the ionization efficiency (ratio of ions to emitted electrons) increased from 0.005 to 0.05 as the pressure is increased between 5×10-6 and 1×10-3 torr. In comparison with EIIs based on thermionic electron sources, the power dissipation reduced from >;1 W to 100 mW.

  • a micro ionizer for portable Mass Spectrometers using double gated isolated vertically aligned carbon nanofiber arrays
    International Electron Devices Meeting, 2007
    Co-Authors: L.-y. Chen, X. Wang, L F Velasquezgarcia, A. I. Akinwande
    Abstract:

    We report micro-fabricated double-gated vertically aligned carbon nanofiber (CNF) arrays for ionization of gasses in low power portable Mass Spectrometers. The devices can be operated in one of two modes - electron impact ionization (EII ) or field ionization (FI). When operated as electron impact ionizer, power dissipation was reduced from >1 W typical of thermionic emission based electron impact ionizers to <100 mW. When operated as a field ionizer, the turn-on voltage for field ionization is reduced from 5-10 kV typical of ungated ionizers to 350 V.

  • A Micro Ionizer for Portable Mass Spectrometers using Double-gated Isolated Vertically Aligned Carbon Nanofiber Arrays
    2007 IEEE International Electron Devices Meeting, 2007
    Co-Authors: L.-y. Chen, L. F. Velasquez-garcia, X. Wang, A. I. Akinwande
    Abstract:

    We report micro-fabricated double-gated vertically aligned carbon nanofiber (CNF) arrays for ionization of gasses in low power portable Mass Spectrometers. The devices can be operated in one of two modes - electron impact ionization (EII ) or field ionization (FI). When operated as electron impact ionizer, power dissipation was reduced from >1 W typical of thermionic emission based electron impact ionizers to

L.-y. Chen - One of the best experts on this subject based on the ideXlab platform.

  • A Microionizer for Portable Mass Spectrometers Using Double-Gated Isolated Vertically Aligned Carbon Nanofiber Arrays
    IEEE Transactions on Electron Devices, 2011
    Co-Authors: L.-y. Chen, L. F. Velasquez-garcia, X. Wang, A. I. Akinwande
    Abstract:

    We report a gas ionizer based on arrays of microfabricated double-gated isolated vertically aligned carbon nanofibers (VA-CNFs) for application in low-power portable Mass Spectrometers. Field-emitted electrons from VA-CNFs are accelerated to high energy and subsequently collide with neutral gas molecules, leading to ionization/fragmentation of the molecules. Double-gated field-emitter arrays with isolated VA-CNF tips were fabricated using a photoresist planarization technique. Two types of devices were fabricated and characterized. The first type of device has the emitter tip in the same plane as the extraction gate, and the second type of device has the emitter tip 900 nm below the extraction gate. All devices were made using a process that results in gate and focus diameters of 1.7 and 4.2 μm, respectively. When operated as a field-emitted electron impact ionizer (EII), for the same ion current, the ionization efficiency (ratio of ions to emitted electrons) increased from 0.005 to 0.05 as the pressure is increased between 5×10-6 and 1×10-3 torr. In comparison with EIIs based on thermionic electron sources, the power dissipation reduced from >;1 W to 100 mW.

  • a micro ionizer for portable Mass Spectrometers using double gated isolated vertically aligned carbon nanofiber arrays
    International Electron Devices Meeting, 2007
    Co-Authors: L.-y. Chen, X. Wang, L F Velasquezgarcia, A. I. Akinwande
    Abstract:

    We report micro-fabricated double-gated vertically aligned carbon nanofiber (CNF) arrays for ionization of gasses in low power portable Mass Spectrometers. The devices can be operated in one of two modes - electron impact ionization (EII ) or field ionization (FI). When operated as electron impact ionizer, power dissipation was reduced from >1 W typical of thermionic emission based electron impact ionizers to <100 mW. When operated as a field ionizer, the turn-on voltage for field ionization is reduced from 5-10 kV typical of ungated ionizers to 350 V.

  • A Micro Ionizer for Portable Mass Spectrometers using Double-gated Isolated Vertically Aligned Carbon Nanofiber Arrays
    2007 IEEE International Electron Devices Meeting, 2007
    Co-Authors: L.-y. Chen, L. F. Velasquez-garcia, X. Wang, A. I. Akinwande
    Abstract:

    We report micro-fabricated double-gated vertically aligned carbon nanofiber (CNF) arrays for ionization of gasses in low power portable Mass Spectrometers. The devices can be operated in one of two modes - electron impact ionization (EII ) or field ionization (FI). When operated as electron impact ionizer, power dissipation was reduced from >1 W typical of thermionic emission based electron impact ionizers to

X. Wang - One of the best experts on this subject based on the ideXlab platform.

  • A Microionizer for Portable Mass Spectrometers Using Double-Gated Isolated Vertically Aligned Carbon Nanofiber Arrays
    IEEE Transactions on Electron Devices, 2011
    Co-Authors: L.-y. Chen, L. F. Velasquez-garcia, X. Wang, A. I. Akinwande
    Abstract:

    We report a gas ionizer based on arrays of microfabricated double-gated isolated vertically aligned carbon nanofibers (VA-CNFs) for application in low-power portable Mass Spectrometers. Field-emitted electrons from VA-CNFs are accelerated to high energy and subsequently collide with neutral gas molecules, leading to ionization/fragmentation of the molecules. Double-gated field-emitter arrays with isolated VA-CNF tips were fabricated using a photoresist planarization technique. Two types of devices were fabricated and characterized. The first type of device has the emitter tip in the same plane as the extraction gate, and the second type of device has the emitter tip 900 nm below the extraction gate. All devices were made using a process that results in gate and focus diameters of 1.7 and 4.2 μm, respectively. When operated as a field-emitted electron impact ionizer (EII), for the same ion current, the ionization efficiency (ratio of ions to emitted electrons) increased from 0.005 to 0.05 as the pressure is increased between 5×10-6 and 1×10-3 torr. In comparison with EIIs based on thermionic electron sources, the power dissipation reduced from >;1 W to 100 mW.

  • a micro ionizer for portable Mass Spectrometers using double gated isolated vertically aligned carbon nanofiber arrays
    International Electron Devices Meeting, 2007
    Co-Authors: L.-y. Chen, X. Wang, L F Velasquezgarcia, A. I. Akinwande
    Abstract:

    We report micro-fabricated double-gated vertically aligned carbon nanofiber (CNF) arrays for ionization of gasses in low power portable Mass Spectrometers. The devices can be operated in one of two modes - electron impact ionization (EII ) or field ionization (FI). When operated as electron impact ionizer, power dissipation was reduced from >1 W typical of thermionic emission based electron impact ionizers to <100 mW. When operated as a field ionizer, the turn-on voltage for field ionization is reduced from 5-10 kV typical of ungated ionizers to 350 V.

  • A Micro Ionizer for Portable Mass Spectrometers using Double-gated Isolated Vertically Aligned Carbon Nanofiber Arrays
    2007 IEEE International Electron Devices Meeting, 2007
    Co-Authors: L.-y. Chen, L. F. Velasquez-garcia, X. Wang, A. I. Akinwande
    Abstract:

    We report micro-fabricated double-gated vertically aligned carbon nanofiber (CNF) arrays for ionization of gasses in low power portable Mass Spectrometers. The devices can be operated in one of two modes - electron impact ionization (EII ) or field ionization (FI). When operated as electron impact ionizer, power dissipation was reduced from >1 W typical of thermionic emission based electron impact ionizers to

L. F. Velasquez-garcia - One of the best experts on this subject based on the ideXlab platform.

  • A Microionizer for Portable Mass Spectrometers Using Double-Gated Isolated Vertically Aligned Carbon Nanofiber Arrays
    IEEE Transactions on Electron Devices, 2011
    Co-Authors: L.-y. Chen, L. F. Velasquez-garcia, X. Wang, A. I. Akinwande
    Abstract:

    We report a gas ionizer based on arrays of microfabricated double-gated isolated vertically aligned carbon nanofibers (VA-CNFs) for application in low-power portable Mass Spectrometers. Field-emitted electrons from VA-CNFs are accelerated to high energy and subsequently collide with neutral gas molecules, leading to ionization/fragmentation of the molecules. Double-gated field-emitter arrays with isolated VA-CNF tips were fabricated using a photoresist planarization technique. Two types of devices were fabricated and characterized. The first type of device has the emitter tip in the same plane as the extraction gate, and the second type of device has the emitter tip 900 nm below the extraction gate. All devices were made using a process that results in gate and focus diameters of 1.7 and 4.2 μm, respectively. When operated as a field-emitted electron impact ionizer (EII), for the same ion current, the ionization efficiency (ratio of ions to emitted electrons) increased from 0.005 to 0.05 as the pressure is increased between 5×10-6 and 1×10-3 torr. In comparison with EIIs based on thermionic electron sources, the power dissipation reduced from >;1 W to 100 mW.

  • A Micro Ionizer for Portable Mass Spectrometers using Double-gated Isolated Vertically Aligned Carbon Nanofiber Arrays
    2007 IEEE International Electron Devices Meeting, 2007
    Co-Authors: L.-y. Chen, L. F. Velasquez-garcia, X. Wang, A. I. Akinwande
    Abstract:

    We report micro-fabricated double-gated vertically aligned carbon nanofiber (CNF) arrays for ionization of gasses in low power portable Mass Spectrometers. The devices can be operated in one of two modes - electron impact ionization (EII ) or field ionization (FI). When operated as electron impact ionizer, power dissipation was reduced from >1 W typical of thermionic emission based electron impact ionizers to

Stephen Taylor - One of the best experts on this subject based on the ideXlab platform.

  • development of quadrupole Mass Spectrometers using rapid prototyping technology
    Journal of the American Society for Mass Spectrometry, 2009
    Co-Authors: Boris Brkic, Paul R. Chalker, Christopher John Sutcliffe, Adam T. Clare, Stephen Taylor
    Abstract:

    In this report, we present a prototype design of a quadrupole Mass filter (QMF) with hyperbolic electrodes, fabricated at the University of Liverpool using digital light processing (DLP), a low-cost and lightweight 3D rapid prototyping (RP) technique. Experimental Mass spectra are shown for H2+, D2+, and He+ ions to provide proof of principle that the DLP Mass filter is working as a Mass analyzer in the low-Mass range (1 to 10 amu). The performance of the DLP QMF has also been investigated for individual spectral peaks. Numerical simulations of the instrument were performed by coupling CPO and Liverpool QMS-2 programs to model both the ion source and Mass filter, respectively, and the instrument is shown to perform as predicted by theory. DLP thus allows miniaturization of Mass Spectrometers at low cost, using hyperbolic (or other) geometries of Mass analyzer electrodes that provide optimal ion manipulation and resolution for a given application. The potential of using RP fabrication techniques for developing miniature and microscale Mass analyzers is also discussed.

  • Development of Quadrupole Mass Spectrometers Using Rapid Prototyping Technology
    Journal of the American Society for Mass Spectrometry, 2009
    Co-Authors: Boris Brkić, Neil France, Paul R. Chalker, Christopher John Sutcliffe, Adam T. Clare, Stephen Taylor
    Abstract:

    In this report, we present a prototype design of a quadrupole Mass filter (QMF) with hyperbolic electrodes, fabricated at the University of Liverpool using digital light processing (DLP), a low-cost and lightweight 3D rapid prototyping (RP) technique. Experimental Mass spectra are shown for H2+, D2+, and He+ ions to provide proof of principle that the DLP Mass filter is working as a Mass analyzer in the low-Mass range (1 to 10 amu). The performance of the DLP QMF has also been investigated for individual spectral peaks. Numerical simulations of the instrument were performed by coupling CPO and Liverpool QMS-2 programs to model both the ion source and Mass filter, respectively, and the instrument is shown to perform as predicted by theory. DLP thus allows miniaturization of Mass Spectrometers at low cost, using hyperbolic (or other) geometries of Mass analyzer electrodes that provide optimal ion manipulation and resolution for a given application. The potential of using RP fabrication techniques for developing miniature and microscale Mass analyzers is also discussed. © 2009 American Society for Mass Spectrometry.