Molding PDMS Channels and an Embedded Detector Chamber

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Molding PDMS Channels and an Embedded Detector
Chamber

• Takaya Ueda
• MASc Candidate
• Simon Fraser University
• July 25, 2006

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Overview

• Background
• Objective
• Motivation
• Design
• Results
• Conclusion
• Current work

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Background

• Microfluidics
• Delivering liquid through narrow channels (µm
  diameter)
• Small sample and chemical volume
• Biomedical applications
• e.g. Single cell testing and analysis

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Background

• SU-8
• Negative photoresist
• Solid after cross-linking
• Poly-dimethylsiloxane (PDMS)
• Silicone elastomer
• Applied as mold
• Optically transparent once cured

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SU-8 and PDMS

• Using SU-8 and PDMS together can rapidly
  fabricate multiple copies of a structure
• Pattern structures with SU-8
• Pour PDMS on top of the SU-8
• Peal off the PDMS after cure
• Repeat 1-3 as necessary
• Rapid processing enables fabrication of low cost
  disposable devices

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Motivation

• Cells react to laser light or drugs
• Reaction causes fluorescence
• Photo-multiplier tube (PMT) used to detect and
  analyze the light
• Problem
• PMT and laser are large and expensive compared to
  the channels

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Final Objective

• Fabricate a single cell analysis system for
  fluorescence detection
• With integrated
• Photo-diode to replace the PMT
• LED to replace the laser

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Current Objective

• Fabricate
• 50 µm diameter channels
• Photo-detector mount
• Both fabricated by molding using SU-8 and PDMS

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Design Overview
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Channel Design
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Results

• Successful fabrication of SU-8 channel and
  detector mounts
• Problems with air bubbles in PDMS
• Air bubbles affect transparency of PDMS to the
  eye, photo-diode, and LED

SU-8 Channels SU-8 Detector Mount
PDMS Channel
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Conclusion

• Successful fabrication of the SU-8 structures
• PDMS process must be improved to eliminate air
  bubbles to yield usable devices

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Current Work

• PDMS results have improved because of better
  processing
• Currently researching world-to-chip electrical
  connections with PDMS

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Questions?