Johns Hopkins University

Timothy J Cornish

Scott A Ecelberger

Robert J Cotter

Harry K Charles, Jr

Paul D Wienhold

Wayne A Bryden

Michael P McLoughlin

Micah A Carlson

Charles W Anderson

Arthur S Francomacaro

William R Allmon

James T Velky

David M Lee

Nicholas H Evancich

Daniel J DeCicco

Allen C Keeney

Frederick P Gick

A miniature time-of-flight mass spectrometer (TOF-MS) and method for increasing the collection efficiency of laser-desorbed ions in a miniature time-of-flight mass spectrometer (TOF-MS) is provided. The method provides a laser pulse generated by an ionization extraction device within the TOF-MS; maintains a sample plate potential at a ground level for a fixed delay period of about 50 ns; and uses a high voltage switch to sharply increase the sample plate potential up to 10 kV/mm.

Time- of flight mass spectrometers for improving resolution and mass employing an impulse extraction ion source

A gating grid for deflecting ions includes an insulating substrate (), a conducting layer () adhered to the insulating substrate (), and interdigitated electrodes () patterned in the conducting layer by a photolithographic process. A hole () in the insulating substrate beneath the interdigitated electrodes allows ions to pass through the hole in the substrate. A process for making a gating grid for deflecting ions includes adhering a conducting layer () to an insulating substrate (), forming interdigitated electrodes () on the conducting layer (), and then forming a hole () in the insulating substrate beneath the interdigitated electrodes.

Gating grid and method of making same

A method is provided for reducing signal ringing in a microchannel plate detector assembly having a cylindrical mount with a center tube extending through at least a portion of the assembly, in a mass spectrometer including the steps of providing the microchannel plate detector assembly with a pin anode extending from the cylindrical mount and located in proximity to the center tube; holding a front portion of the assembly at ground potential; setting a middle portion of the assembly between the front portion and a rear portion to a first voltage potential for accelerating ions; holding the rear portion of the assembly to a second voltage potential; holding the pin anode at a third voltage potential; and accelerating electrons emitted from the middle portion of the assembly toward the pin anode. The third voltage potential is established by an amplifier of an oscilloscope connected to the detector assembly.

Microchannel plate detector assembly for a time-of-flight mass spectrometer

A modular aerosol sample detection system is provided comprising a sample collector couplable to an aerial vehicle and provided with at least one retrievable collection sample plate, which controllably rotates to collect aerosol samples on a multiplicity of collection spots arranged in multiple concentric tracks on the collection disk, and a multi-channel TOF removably couplable to the collection sampler to analyze the collected samples.

Sample retrieval device for aerosol collection

Techniques for simultaneously detecting direct and reflected ions in a time-of-flight tube () and a source () for generating an ion beam of ions of a sample and introducing the ion beam into a first portion of the flight tube. A reflector () reflects ions from the ion beam in a second portion of the flight tube. A plate () substantially perpendicular to an axis of the ion beam is located between the first portion of the flight tube and the second portion of the flight tube. The plate has a hole through which some ions in the ion beam may pass from the first portion to the second portion of the flight tube. Each of two opposite faces of the plate includes a set of one or more ion detectors (). The technique allows rapid, reliable detection of complex agents in a small number of samples.

Mass spectrometer for simultaneous detection of reflected and direct ions

A field portable mass spectrometer system comprising a sample collector and a sample transporter. The sample transporter interfaces with the sample collector to receive sample deposits thereon. The system further comprises a time of flight (TOF) mass spectrometer. The time of flight mass spectrometer has a sealable opening that receives the sample transported via the sample transporter in an extraction region of the mass spectrometer. The system further comprises a control unit that processes a time series output by the mass spectrometer for a received sample and identifies one or more agents contained in the sample.

Portable time-of-flight mass spectrometer system

A miniature time-of-flight mass spectrometer (TOF-MS) is provided having (1) a gridless, focusing ionization extraction device allowing for the use of very high extraction energies in a maintenance-free design, (2) a miniature flexible circuit-board reflector using rolled flexible circuit-board material, and (3) a low-noise, center-hole microchannel plate detector assembly that significantly reduces the noise (or &ldquo;ringing&rdquo;) inherent in the coaxial design. A method is also provided for increasing the collection efficiency of laser-desorbed ions in the TOF-MS. The method includes the steps of providing within the TOF-MS an ionization extraction device having an unobstructed central chamber having a first region and a second region; creating an ion acceleration/extraction field within the first region; accelerating ions within the first region; de-accelerating the ions in the second region; and drifting the ions in a drift region to cause ion dispersion.

Gridless, focusing ion extraction device for a time-of-flight mass spectrometer

A novel technique utilizing the precision of printed circuit board design and the physical versatility of thin, flexible substrates is disclosed to produce a new type of ion reflector. A precisely defined series of thin conductive strips (traces) are etched onto a flat, flexible circuit board substrate. Preferably, the thin conductive strips are further apart at one end of the substrate and get increasingly closer towards the other end of the substrate. The flexible substrate is then rolled into a tube to form the reflector body, with the conductive strips forming the rings of the ion reflector. The spacing between the traces, and hence the ring spacing, can be readily varied by adjusting the conductor pattern on the substrate sheet during the etching process. By adjusting the spacing between the rings, the characteristics of the field created by the reflectron can be easily customized to the needs of the user.

Method of making an ion reflectron comprising a flexible circuit board

A time-of-flight mass spectrometer (TOF-MS) array instrument is provided. Each TOF-MS of the array instrument includes (1) a gridless, focusing ionization extraction device allowing for the use of very high extraction energies in a maintenance-free design, (2) a fiberglass-clad flexible circuit-board reflector using rolled flexible circuit-board material, and (3) a low-noise, center-hole microchannel plate detector assembly that significantly reduces the noise (or &ldquo;ringing&rdquo;) inherent in the coaxial design. The miniature TOF-MS array allows for the bundling of a plurality of mass analyzers, e.g., a plurality of TOF-MSs, into a single array working in parallel fashion to greatly enhance the throughput of each TOF-MS in the array by multiplexing the data collection process. A preferred embodiment of the TOF-MS array instrument incorporates 16 TOF-MS units that are arranged in mirror-image clusters of eight units.

Time-of-flight mass spectrometer array instrument

Flexboard reflector

A reflectron for use with a mass spectrometer that focuses ions having different energies contains a conductive end cap that is electrically connected to a first voltage. A conductive surface is electrically isolated from the end cap and connected to a second voltage. This conductive surface cooperates with the conductive end cap to establish an inner region in which a non-linear electric field exists. As a result, ions having different energies enter and exit the inner region at a common opening and, when within the inner region, are reflected without penetrating past the conductive surface.

End cap reflection for a time-of-flight mass spectrometer and method of

A reflectron capable of focusing an entire mass range of product ions at substantially the same focal point, comprising a plurality of lens plates, each having an opening therein, for generating a non-linear electric field in the reflectron. To generate the non-linear electric field, the voltage applied to each successive lens plate increases non-linearly with respect to its adjacent lens plate. The voltage of the first lens plate having the opening through which the ions first enter the reflectron is set to a low potential and the voltage being applied to each successive lens plate increases in a non-linear manner with the largest voltage being applied to the lens plate furthest from the first lens plate. This non-linear voltage application, to generate the non-linear electric field, can be achieved by coupling a potentiometer between each lens plate and adjusting each potentiometer accordingly. Alternatively, to generate the non-linear electric field, the lens plates may be unequally spaced and an equal voltage may be applied to each lens plate.

Non-linear field reflectron

A tandem time-of-flight mass spectrometer comprises a grounded vacuum housing, two reflecting-type mass analyzers coupled via a collision chamber, and flight channels electrically floated with respect to the grounded vacuum housing. The first reflecting-type mass analyzer receives ionized molecules (ions). These ions pass through the flight channel of the first reflecting-type mass analyzer and are fragmented in the collision chamber. The fragmented ions pass through the flight channel of the second reflecting-type mass analyzer. Detectors disposed in the collision chamber and in the second reflecting-type mass analyzer detect the spectrum of the first reflecting-type mass analyzer and the spectra of the tandem time-of-flight mass analyzer, respectively.

Growing community of inventors

Catonsville, MD, United States of America

Timothy J Cornish