The fabrication of thin microfluidic devices has resulted in increased knowledge of cellular properties in molecular biology, genetic analysis and proteomics, and neuroscience. Specifically in neuroscience, these devices allow for the differential treatment of cell bodies and their distal axons. Distinct cell properties along with selective barriers in microfluidic devices allow researchers to spatially dissect essential aspects of neuronal signal transduction. We report on the fabrication of a microfluidic device, curing 10µm thick layers of Polydimethylsiloxane (PDMS) and etching 5µm diameter holes using a March Plasma etcher and a grid mask. A variety of masks were employed with limited success, including hard masks that provided insufficient contact with the PDMS membrane, resulting in undercutting. A soft Shipley 1818 photoresist mask, exposed directly onto PDMS with use of conventional photolithography, provided the necessary contact and specificity but was unable to withstand the charged etch species from the plasma source. The PDMS was found to etch at a rate of ~210nm/min at 300W with 18% Sulfur Hexafluoride and 3% Oxygen, with a chamber pressure of 180mTorr. Under identical conditions the S1818 etched at ~2.0µm/min, ~10 times the speed of PDMS. Other resists including SU-8 5 were found to have similar etch rates to S1818, but provided greater precision in application. The high precision of SU-8 5 led us to consider forming 10µm resist posts that will serve as a mold around which to cure PDMS. Conventional soft Lithography and PDMS self-adhesion will be utilized to adhere the cured permeable membrane to its larger PDMS structure. This microfluidic membrane will closely mimic in vivo environments, allowing for the controlled study of axonal injury and regeneration.

Additional Abstract Information

Student(s): Devin E. Buennemeyer

Department: Physics and Astronomy

Faculty Advisor: Dr. Chris Hughes

Type: Oral

Year: 2016

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