1. Molding PDMS Channels and an Embedded Detector Chamber
Takaya Ueda
MASc Candidate
Simon Fraser University
July 25, 2006

2. Overview Background Objective Motivation Design Results Conclusion
Current work
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3. 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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4. Background SU-8 Poly-dimethylsiloxane (PDMS) Negative photoresist
Solid after cross-linking
Poly-dimethylsiloxane (PDMS)
Silicone elastomer
Applied as mold
Optically transparent once cured
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5. 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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6. 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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7. 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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8. Current Objective Fabricate
50 µm diameter channels
Photo-detector mount
Both fabricated by molding using SU-8 and PDMS
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9. Design Overview PDMS Channel Layer PDMS Detector Mount Photo-detector
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10. Channel Design Outlet Inlet Cell Retention Chamber 2800 µm
Inlet for cell retention
50 µm
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11. 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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12. 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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13. Current Work PDMS results have improved because of better processing
Currently researching world-to-chip electrical connections with PDMS
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14. Questions?
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