UV Sterilization Using Microplasma Arrays

1
UV Sterilization Using Microplasma Arrays

• ECE 445 Final Presentation
• Amanda Chang and Leo Hua, Group 27
• TA Ran Hu
• April 28, 2006

2
Outline

• Introduction
• Objectives
• Design Fabrication
• Testing
• Device Performance
• Conclusions

3
Introduction

• Microdischarge technology at the U of I
• Lighting and biomedical applications
• Cost-effectiveness and efficiency

Photos courtesy of http//lope.ece.uiuc.edu/resear
ch/microcavity.htm
4
Objectives

• Apply thin-layered plasma generation devices
  towards ultraviolet generation for sterilization
  purposes
• Expand previous projects into the ultraviolet
  spectrum
• Increase the size of discharge arrays while
  maintaining stable operation

5
Design Fabrication
6
Original Design
7
Preparing Electrodes

• Anodizing Process
• 0.3 M Oxalic acid
• 50 V, 15C, 2 hours
• 10 µm-thick oxide

8
Glass Paste

• (Proprietary Information Removed)

9
Device Assembly

• (Proprietary Information Removed)

10
Testing
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Testing

• Unpackaged Devices
• Verify effective fabrication process
• Evaluate qualitative behavior of device
• I-V Characteristics
• Packaged Devices
• I-V, Output Intensity, Efficiency
• Improvements to each successive device based on
  results

12
Test Setup
13
Device Performance
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Device 1

• (Proprietary Information Removed)

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Device 2

• (Proprietary Information Removed)

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Device 2 I-V Curves
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Emission Spectra
Neon Gas
Argon/N2 Gas
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Device 3

• First packaged device
• Quartz slide provided better uniformity
• Device damaged during UV tests due to high fields
  around the gas inlet hole

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Device 4

• Surrounded hole with epoxy for protection
• New method of applying epoxy to increase flatness
• Tape and epoxy first
• Quartz slide
• Device burnt at top edge during UV test

20
Device 5

• Hole separated from mesh
• Intensity measurements with Neon
• Electrode damaged during testing

21
Device 5 Voltage vs. Intensity
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Device 6

• (Proprietary Information Removed)

23
Device 6 I-V Graph
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Device 6 Output Analysis
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Device 6 Efficiency Analysis

• Efficiency of Commercial Neon Lamp .01

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Conclusions
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Successes Challenges

• Aluminum flatness
• Heat treatment
• New epoxy procedure
• Glass paste thickness
• UV Discharge
• Modified design and extra hole protection
• Addition of polyimide tape spacers
• Fragility of mesh metal contacts
• Silver coating
• Additional wire attachment to mesh electrode

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Improved Design
(Proprietary Information Removed)
29
Recommendations

• (Proprietary Information Removed)

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Ethical Considerations

• Possible Health Risks
• UV radiation can be harmful to the eyes and skin
  especially at lower wavelengths (UV-C)
• Quality Control
• Even small imperfections in the device can result
  in device breakdown
• Lower UV regions not visible so devices need an
  indicator of proper functionality to ensure
  consumer safety

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Thanks

• Sung-Jin Park, visiting professor and mentor
• Gary Eden, Director of the Optical Physics and
  Engineering Laboratory
• Ran Hu, ECE 445 TA
• Kwang-Soo Kim, graduate assistant