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microdischarge devices

 

Versatile Microdischarge Devices

A suite of seven technologies for multiple applications

The University of Illinois at Urbana–Champaign is offering a suite of microdischarge technologies for license and/or joint development by qualified companies.

Microdischarge device technology involves fabricating miniature plasmas (i.e., microballs of ionized gas) that exhibit a unique collection of useful properties. The University’s technologies use silicon and standard microelectronics fabrication techniques to produce microdischarge devices that are robust, small, efficient, and versatile at a low cost.

The University’s suite of seven technologies can be used in many areas, including biomedical applications, displays, and other applications such as lighting systems, sensors, toxic gas remediation, lasers, gas chromatography, and fiber optics.

Additional descriptions of these microdischarge device technologies are presented below.

For more information about UIUC technologies, please visit https://flintbox.com/public/group/779/

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Biomedical Applications

medical applicaitons

View the printable brochure on biomedical applications(link opens new browser window) .

  • Sterilization
    Devices made from these technologies emit light in the VUV, UV, and visible range from a discharge to kill germs for instrument or surface disinfection. The small size and low cost of the devices make them ideal for applications where portability is required, such as cleaning wounds in the field or disinfecting instruments in clinics and hospitals.

  • Phototherapy
    These technologies provide microdischarge devices and arrays that are inexpensive and easy to manufacture in flexible sheets. Flexibility is advantageous in phototherapy applications to provide for more efficient delivery of the light to the area under treatment.

  • Flow Cytometry
    These microdischarge technologies are ideal for illuminating biological specimens to successfully perform flow cytometry, where inexpensive, disposable light source arrays would be desirable.

  • Polymer Curing
    Polymers used in dental and other applications can be cured into solid form using devices made with these technologies, whose small size, low cost, and flexibility are key advantages.
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Display Applications

display applications

View the printable brochure on display applications(link opens new browser window) .

  • Personal Digital Assistants
    The small size and low cost of these microdischarge devices make them ideal for applications where portability is required, such as PDAs and other mini-computers.

  • Micro-Displays
    These technologies provide microdischarge devices and arrays that are inexpensive, robust, and easy to fabricate or integrate with electronics, allowing manufacturers to reduce the costs (or increase profitability) for their high-resolution, extremely small display products, such as tiny displays mounted on eyeglasses. Pixel sizes of 10 µm or lower can be obtained.

  • Flat Panel Displays
    Because they can be small and inexpensively manufactured, these microdischarge technologies are ideal for use in flat panel displays such as flat screen televisions, desktop computer monitors, laptop computers, aircraft display panels, and telephones. The high resolution afforded by these devices makes them ideal for use in high-definition television (HDTV), where crisp, cinema-quality pictures are presented on a wide screen.

  • Flexible Displays
    These technologies provide microdischarge devices and arrays that are inexpensive and easy to manufacture in flexible sheets. Flexible displays might be used when portability is required or when space and weight constraints exist (e.g., a roll-up laptop computer screen).
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Other Applications

"Microdischarge Devices Shed Light on Variety of Applications," article published by ECE Illinois E-News(link opens new browser window) .

Other applications where these microdischarge device technologies might be used include the following:

  • Specialty lighting
    —Flexible lighting
    —High pressure arc lamp starters

  • General lighting

  • Polymer curing, stereolithography, and microetching

  • Sensors
    —Chemical sensing
    —Toxic gas remediation
    —Atmospheric diagnostics
    —Gas chromatography

  • Electronics
    —Microtools (e.g., for noncontact surgery)
    —Lasers (laser cavities, mini UV lasers, gas lasers, microlasers)
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Technology Details

Each of these technologies has been prototyped and tested and is nearly ready for transfer to commercial applications.


Microdischarge Lamp

U.S. Patent #6,016,027(link opens new browser window)
U.S. Patent #6,139,384(link opens new browser window)

The microdischarge lamp has a hollow cathode geometry with the cathode formed in a one-piece substrate, such as a silicon wafer. Integrated circuit micromachining and fabrication techniques are used to form microcavities in the substrate. The substrate consists of a conductive layer, topped by a dielectric, topped by another conductive layer. The microcavity is filled with a gas. When a voltage is applied across the layers, a discharge occurs and light is emitted. This technology is 100% owned by the University.

Benefits

  • Inexpensive: The method uses well-entrenched integrated circuit micromachining and fabrication techniques to form the microcavities inexpensively. Also, this lamp can be fabricated in one substrate, unlike in previous methods.
  • Efficient: The small dimensions that are possible with this design permit the efficient production of light from new radiators.
  • Easier to mass produce: The mass production techniques used to produce these lamps are readily available.
  • High gas pressures: The dimensions of the discharge lamp can be made so small that the gas pressure can be raised well above what is possible with a conventional discharge lamp, while still producing wavelengths that are not possible from other lamps.

Publications

  • "Microdischarge Devices Fabricated in Silicon," published Sept. 1, 1997, in Applied Physics Letters (link opens new browser window) 71(9):1165–1167.
  • "Planar Microdischarge Arrays," published July 23, 1998, in Electronics Letters (link opens new browser window) 34(15): 1529–1531.
  • "Continuous-Wave Emission in the Ultraviolet from Diatomic Excimers in a Microdischarge," published May 25, 1998, in Applied Physics Letters (link opens new browser window) 72(21):2634–2636.
  • "Microdischarge Arrays: A New Family of Photonic Devices," published Jan./Feb. 2002 in IEEE Journal on Selected Topics in Quantum Electronics (link opens new browser window) 8(1):139–147.
  • "Arrays of Silicon Microdischarge Devices with Multicomponent Dielectrics," published Nov. 15, 2001, in Optics Letters (link opens new browser window) 26(22):1773–1775.
  • "Performance of Microdischarge Devices and Arrays with Screen Electrodes," published Jan. 2001 in IEEE Photonics Technology Letters (link opens new browser window) 13(1):61-63.

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Microdischarge Lamp and Array

U.S. Patent #6,194,833(link opens new browser window)

This multilayer microdischarge device has three components: (1) a silicon substrate acting as a planar electrode, (2) a dielectric layer deposited onto the silicon substrate, and (3) a top conducting film. Cavities are machined into the conducting and dielectric layers to expose the silicon; these cavities then are filled with gas or vapor. When a voltage is applied between the silicon and conducting film, a plasma is formed inside the cavity. This technology is 100% owned by the University.

Benefits

  • Easily produced in arrays: Because both electrodes are planar, manufacturing is greatly simplified, and the microdischarge devices can be easily produced in arrays.
  • Simply manufactured: Microdischarge devices take advantage of well-established silicon processing methods and are thus easily fabricated.
  • Versatility of use: The devices work well not only with gases but also with low vapor pressure materials that require heating.

Publications

  • "Planar Microdischarge Arrays," published July 23, 1998, in Electronics Letters (link opens new browser window) 34(15): 1529–1531.
  • "Arrays of Silicon Microdischarge Devices with Multicomponent Dielectrics," published Nov. 15, 2001, in Optics Letters (link opens new browser window) 26(22):1773–1775.
  • "Independently Addressable Subarrays of Silicon Microdischarge Devices: Electrical Characteristics of Large (30x30) Arrays and Excitation of a Phosphor," published Sept. 24, 2001, in Applied Physics Letters (link opens new browser window) 79(13):2100–2102.
  • "Arrays of Microdischarge Devices Having 50–100 µm Square Pyramidal Si Anodes and Screen Cathodes," published Feb. 1, 2001, in Electronics Letters (link opens new browser window) 37(3):171-172.
  • "Silicon Microdischarge Devices Having Inverted Pyramidal Cathodes: Fabrication and Performance of Arrays," published Jan. 22, 2001, in Applied Physics Letters (link opens new browser window) 78(4):419–421.
  • "Performance of Microdischarge Devices and Arrays with Screen Electrodes," published Jan. 2001 in IEEE Photonics Technology Letters (link opens new browser window) 13(1):61-63.

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Flexible Microdischarge Device/Array

This technology is used to produce flexible microdischarge devices and arrays inexpensively. Inexpensive materials, such as copper coil, are used as the cathode as well as for flexible support for the device. A thin film of polyimide serves as the dielectric, and a thin metallic film acts as the anode. A channel is machined through these three layers and is filled with a suitable gas. When a voltage is applied across the layers, a discharge is produced. This technology is 100% owned by the University.

Benefits

  • Reduced cost: Use of less expensive materials and novel design reduce the production cost.
  • Mass production possible: The small overall thickness of the layers allows for manufacturing of these devices to be accomplished in large sheets using "roll-to-roll" manufacturing.

Publications

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Multilayer Ceramic Microdischarge Device

This device is fabricated using multilayer ceramic integrated circuit (MCIC) technology to form the cavity and electrode structure. Essentially, an MCIC capacitor structure is fabricated, and then a hole is drilled into the structure. The resulting device has a through-hole and can be used with interdigitated electrodes. This technology is 100% owned by the University.

Benefits

  • Resistance to harsh environments: The ceramic materials of the device make it suitable for use at high temperatures and in harsh chemical environments, making it ideal for use in the remediation of toxic gases.
  • Small size: Since the device can be easily integrated with other components, such as MCIC inductors and capacitors as well as with hybrid packaged silicon integrated circuits, it can be much smaller in size.

Publications

  • "Multistage, Monolithic Ceramic Microdischarge Device Having an Active Length of ~0.27 mm," published March 5, 2001, in Applied Physics Letters (link opens new browser window) 78(10):1340–1342
  • "Performance of Microdischarge Devices and Arrays with Screen Electrodes," published Jan. 2001 in IEEE Photonics Technology Letters (link opens new browser window) 13(1):61-63.

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All-Silicon Microdischarge

This technology is a means of exciting a microdischarge using a reverse-biased pn junction or Schottky diode, where the entire device is made from one silicon wafer. In this configuration, the depletion region behaves like the dielectric layer in the other configurations, resulting in a more simply fabricated and robust microdischarge device. Since the width of the depletion region depends on the magnitude of the voltage bias, the device behaves as if it has a variable thickness dielectric that can be controlled at will. This technology is 100% owned by the University.

Benefits

  • Simple fabrication: Since the entire device is made from one material, it is fabricated simply. Also, the cavity is more easily drilled through one material rather than three
  • Robust device: With silicon as the material—and since silicon is virtually impervious to sputtering—the overall device is more robust.
  • Variable dielectric: Since the width of the depletion region depends on the magnitude of the voltage bias, the device behaves as if it has a variable thickness dielectric that can be controlled at will.
  • Ability to function at radio frequencies: Adjusting the voltage bias brings the device into resonance with the frequency of the driver, allowing it to be run at radio frequencies (RF). RF discharges are desirable because they are efficient, have long lifetimes, and provide low-cost sources of light for use in low-cost communication systems.

Publications

  • "Excitation of a Microdischarge with a Reverse-Biased pn Junction," published Feb. 5, 2001, in Applied Physics Letters (link opens new browser window) 78(6):709–711.
  • "Performance of Microdischarge Devices and Arrays with Screen Electrodes," published Jan. 2001 in IEEE Photonics Technology Letters (link opens new browser window) 13(1):61-63.

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Starting and Reigniting Arc Lamps

This technology is a method for more easily igniting and reigniting high-pressure arc lamps. It adds microdischarge devices to produce and inject electrons to augment electron production in the early stages of lamp ignition or reignition so that less voltage and time are required to ignite the lamp. This technology is jointly owned by the University and APL Engineered Materials, Inc.

Benefits

  • Easier and faster ignition: The discharge augments electron production in the ignition system of the lamp so that less voltage (by at least a factor of 2) and less time are required to ignite the lamp than without starting aids.
  • Extended lifetime: Each time a lamp is ignited, it loses 10 hours of its overall lifetime due to the extremely high voltage peak required for ignition. Decreasing that voltage significantly could increase the lamp’s useful lifetime.

Publications

  • "Reduction in the Breakdown Voltage of a High Pressure Discharge with an Array of 200-400 µm Diameter Microdischarges: Application to Arc Lamp Ignition," published Feb. 2002 in IEEE Transactions on Plasma Science (link opens new browser window) 30(1, part 1):194–195.
  • "Microdischarge Array-Assisted Ignition of a High-Pressure Discharge: Application to Arc Lamps," published Dec. 24, 2001, in Applied Physics Letters (link opens new browser window) 79(26):4304–4306.
  • "Performance of Microdischarge Devices and Arrays with Screen Electrodes," published Jan. 2001 in IEEE Photonics Technology Letters (link opens new browser window) 13(1):61-63.

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Thin, Lightweight Microdischarge Devices/Arrays

This microdischarge device is formed from a semiconductor electrode with a cavity, an insulating layer, and a second electrode. The cavity in the silicon is a square-pyramid shape, and shape would vary depending on the semiconductor used. Multiple devices may be fabricated in one silicon wafer to produce an array. This invention can be used with any of the other inventions that make use of semiconductor systems.

Benefits

  • Inexpensive: Tapered cavities are relatively inexpensive and easy to fabricate using conventional semiconductor processing techniques.
  • Superior performance: The resulting devices have superior electrical and optical characteristics and lifetimes compared to those of conventional microdischarge devices. Arrays of the devices produce considerable output power and exhibit ignition characteristics superior to those of conventional arrays of devices.
  • Enabling: The large positive differential resistance of devices with tapered arrays decreases power consumption, while the linearity of the V-I characteristics permits self-ballasting of the devices and simplifies external control circuitry.
  • More efficient: Sides of cavity can be coated with a thin film of material to reflect light in the spectral region of interest and improve the efficiency for extracting light from a microdischarge device.

Publications

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Commercial Opportunity

The University of Illinois at Urbana–Champaign is offering its microdischarge device technologies for license by and/or joint development with commercial companies, universities, or government labs.

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For More Information

For more information about UIUC technologies, please visit https://flintbox.com/public/group/779/

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This technology is owned by the University of Illinois at Urbana–Champaign
T96094 (UI01-001)