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December 2001

The Laboratory
in the News

Commentary by
Rokaya Al-Ayat

Simulation-Aided
Design of
Microfluidic Devices

Small Science
Gets to the Heart
of Matter

When Lethal
Agents Rain from
the Sky

Technology to
Helps Diabetics

Patents

Awards

 

 

Patents

Steve P. Swierkowski, James C. Davidson, Joseph W. Balch
Vacuum Fusion Bonding of Glass Plates
U.S. Patent 6,289,695 B1
September 18, 2001
An improved apparatus and method for vacuum fusion bonding of large, patterned glass plates. One or both glass plates are patterned with etched features such as microstructure capillaries and a vacuum pump-out moat, with one plate having at least one hole through it for communication with a vacuum pump-out fixture. The plates are accurately aligned with a temporary clamping fixture until the start of the fusion-bonding heat cycle. A complete, void-free fusion bond of seamless, full-strength quality is obtained through the plates because the glass is heated well into its softening point and because a large, distributed force is developed that presses the two plates together. This pressure is caused by the vacuum drawn from the difference in pressure between the furnace ambient (high pressure) and the channeling and microstructures in the plates (low pressure). The apparatus and method may be used to fabricate microcapillary arrays for chemical electrophoresis; for example, any apparatus using a network of microfluidic channels embedded between plates of glass or similar moderate melting point substrates with a gradual softening point curve, or for assembly of glass-based substrates onto larger substrates, such as in flat-panel display systems.

Joe N. Lucas, Tore Straume, Kenneth T. Bogen
Kit for Detecting Nucleic Acid Sequences Using Competitive Hybridization Probes
U.S. Patent 6,270,972 B1
August 7, 2001
A kit for detecting a target nucleic acid sequence in a sample. The kit contains four hybridization probes. A first hybridization probe includes a nucleic acid sequence that is sufficiently complementary to selectively hybridize to a first portion of the target sequence. The first hybridization probe includes a first complexing agent for forming a binding pair with a second complexing agent. A second hybridization probe includes a nucleic acid sequence that is complementary to selectively hybridize to a second portion of the target sequence to which the first hybridization probe does not selectively hybridize. The second hybridization probe includes a detectable marker. A third hybridization probe includes a nucleic acid sequence that is sufficiently complementary to selectively hybridize to a first portion of the target sequence. The third probe includes the same detectable marker as the second hybridization probe. A fourth hybridization probe includes a nucleic acid sequence that is sufficiently complementary to selectively hybridize to a second portion of the target sequence to which the third hybridization probe does not selectively hybridize. The fourth probe includes the first complexing agent for forming a binding pair with the second complexing agent.
The first and second hybridization probes are capable of simultaneously hybridizing to the target sequence, and the third and fourth hybridization probes are capable of simultaneously hybridizing to the target sequence. The detectable marker is not present on the first or fourth hybridization probes, and the first, second, third, and fourth hybridization probes include a competitive nucleic acid sequence sufficiently complementary to a third portion of the target sequence that the competitive sequences of the first, second, third, and fourth hybridization probes compete with each other to hybridize to the third portion of the target sequence.

Alex V. Hamza, Thomas Schenkel, Alan V. Barnes, Dieter H. Schneider
Highly Charged Secondary Ion Mass Spectroscopy
U.S. Patent 6,291,820 B1
September 18, 2001
A secondary ion mass spectrometer using slow, highly charged ions produced in an electron-beam ion trap permits ultrasensitive surface analysis and high spatial resolution simultaneously. The spectrometer comprises an ion source producing a primary ion beam of highly charged ions that are directed at a target surface, a mass analyzer, and a microchannel plate detector of secondary ions that are sputtered from the target surface after interaction with the primary beam. The unusually high secondary ion yield permits the use of coincidence counting, in which the secondary ion stops are detected in coincidence with a particular secondary ion. The association of specific molecular species can be correlated. The unique multiple secondary nature of the highly charged ion interaction enables this new analytical technique.

Joseph W. Balch, Laurence R. Brewer, James C. Davidson, Joseph R. Kimbrough
System and Method for Chromatography and Electrophoresis Using Circular Optical Scanning
U.S. Patent 6,296,749 B1
October 2, 2001
A system and method for chromatography and electrophoresis using circular optical scanning. One or more rectangular microchannel plates or radial microchannel plates have a set of analysis channels for insertion of molecular samples. One or more scanning devices repeatedly pass over the analysis channels in one direction at a predetermined rotational velocity and with a predetermined rotational radius. The rotational radius may be dynamically varied to monitor the molecular sample at various positions along an analysis channel. Sample-loading robots may also be used to deliver molecular samples into the analysis channels. As a third step, the scanning device is passed over the analysis channels at dynamically varying distances from a center point of the scanning device. As a fourth step, molecular samples are loaded into the analysis channels with a robot.

John W. Elmer, Alan T. Teruya
Enhanced Modified Faraday Cup for Determination of Power Density Distribution of Electron Beams
U.S. Patent 6,300,755 B1
October 9, 2001
An improved tomographic technique for determining the power distribution of an electron or ion beam. It uses electron-beam profile data acquired by an enhanced, modified Faraday cup to create an image of the current density in high- and low-power ion or electron beams. A refractory metal disk with a number of radially extending slits, with one slit being about twice the width of the other slits, is placed above a Faraday cup. The electron or ion beam is swept in a circular pattern so that its path crosses each slit in a perpendicular manner. By this means, all the data needed for a reconstruction are acquired in one circular sweep. The enlarged slit enables the beam profile to be oriented with respect to the coordinates of a welding chamber. A second disk, also having slits, is positioned below the first slit disk and inside the Faraday cup. This second disk provides
a shield to prevent the majority of secondary electrons and ions from leaving the Faraday cup. A ring is located below the second slit disk to help minimize the amount of secondary electrons and ions produced. In addition, a beam trap is located in the Faraday cup to provide even more containment of the electron or ion beam when full beam current is being examined through the center hole of the modified Faraday cup.

Steve P. Swierkowski, James C. Davidson, Joseph W. Balch
Vacuum Fusion Bonded Glass Plates Having Microstructures Thereon
U.S. Patent 6,301,931 B1
October 16, 2001
An improved apparatus and method for vacuum-fusion bonding of large, patterned glass plates. One or both glass plates are patterned with etched features, such as microstructure capillaries and a vacuum pump-out moat. One of the plates has at least one hole through it for communicating with a vacuum pump-out fixture. The plates are accurately aligned and temporarily clamped together until the start of the fusion-bonding heat cycle. A complete, void-free fusion bond of seamless, full-strength quality is obtained through the plates. This fusion bond occurs because the glass has been heated well into its softening point and a large, distributed force has developed from the drawn vacuum—caused by the difference in pressure between the furnace ambient (high pressure) and the channeling and microstructures in the plates (low pressure)—which presses the two plates together. The apparatus and method may be used to fabricate microcapillary arrays for chemical electrophoresis. Examples include any apparatus using a network of microfluidic channels embedded between plates of glass or similar moderate-melting-point substrates with a gradual softening point curve, or systems in which glass-based substrates are assembled onto larger substrates, such as in flat-panel display systems.

Kurt H. Weiner, Paul G. Carey
Method of Making Self-Aligned Lightly-Doped-Drain Structure for MOS Transistors
U.S. Patent 6,303,446 B1
October 16, 2001
A process for fabricating lightly doped drains (LDDs) for short-channel metal-oxide semiconductor (MOS) transistors. The process uses a pulsed laser to incorporate the dopants, which eliminates the need for oxide deposition and etching beforehand. During the process, the silicon in the source-drain region is melted by laser energy. Impurities from the gas phase diffuse into the molten silicon to appropriately dope the source-drain regions. By controlling the energy of the laser, an LDD can be formed in one processing step. First, a single high-energy laser pulse melts the silicon to a significant depth. The amount of dopant incorporated into the silicon is small, and furthermore, the dopants diffuse to the edge of the MOS transistor gate structure. Next, many lower-energy laser pulses are used to heavily dope only the source-drain silicon in a very shallow region. Because of two-dimensional heat transfer at the MOS transistor gate edge, the low-energy pulses are inset from the region initially doped by the high-energy pulse. By controlling the laser energy from a computer, the single high-energy laser pulse and the subsequent low-energy laser pulses are carried out in a single operational step to produce a self-aligned LDD structure.

Michael D. Perry, Paul S. Banks, Brent C. Stuart
Method to Reduce Damage to Backing Plate
U.S. Patent 6,303,901 B1
October 16, 2001
The present invention is a method for penetrating a workpiece using an ultrashort-pulse laser beam without causing damage to subsequent surfaces facing the laser. Several embodiments are shown that place holes in fuel injectors without damaging the back surface of the sack in which the fuel is ejected. In one embodiment, pulses from an ultrashort-pulse laser remove about 10 to 1,000 nanometers of material per pulse. In another embodiment, a plasma source is attached to the fuel injector and initiated by common methods such as microwave energy. In a third embodiment of the invention, the sack void is filled with a solid. In a fourth embodiment, a high-viscosity liquid is placed within the sack. In general, high-viscosity liquids preferably used in this invention should have a high damage threshold and a diffusing property.

William F. Krupke, Stephen A. Payne, Christopher D. Marshall
Blue Diode-Pumped Solid-State Laser Based on Ytterbium Doped Laser Crystals Operating on the Resonance Zero-Phonon Transition
U.S. Patent 6,304,584 B1
October 16, 2001
The invention provides an efficient, compact means of generating blue laser light at a wavelength near approximately 493 ± 3 nanometers, based on the use of a laser diode–pumped, ytterbium-doped laser crystal emitting on its zero-phonon line (ZPL) resonance transition at a wavelength near approximately 986 ± 6 nanometers, whose fundamental infrared output radiation is harmonically doubled into the blue spectral region. The invention is applied to the excitation
of biofluorescent dyes (in the approximately 490- to 496-nanometer spectral region) used in flow cytometry, immunoassay, DNA sequencing, and other biofluorescence instruments. The preferred host crystals have strong ZPL fluorescence (laser) transitions lying in the spectral range from approximately 980 to 992 nanometers (so that when frequency-doubled, they produce output radiation
in the spectral range from 490 to 496 nanometers). Alternate preferred ytterbium-doped tungstate crystals, such as Yb:KY(WO4)2,
may be configured to lase on the resonant ZPL transition near
981 nanometers (in lieu of the normal 1,025-nanometer transition).
The laser light is then doubled in the blue at 490.5 nanometers.

 

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