Cloning SU8 silicon masters using epoxy resins to increase feature replicability and production for cell culture devices |
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| Authors: | J W Kamande Y Wang A M Taylor |
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| Institution: | 1.UNC/NCSU Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Campus Box 7575, Chapel Hill, North Carolina 27599-7575, USA;2.Department of Chemistry, University of North Carolina at Chapel Hill, Campus Box 3290, Chapel Hill, North Carolina 27599, USA;3.UNC Neuroscience Center, Chapel Hill, North Carolina 27599, USA;4.Carolina Institute for Developmental Disabilities, Carrboro, North Carolina 27510, USA |
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| Abstract: | In recent years, there has been a dramatic increase in the use of poly(dimethylsiloxane) (PDMS) devices for cell-based studies. Commonly, the negative tone photoresist, SU8, is used to pattern features onto silicon wafers to create masters (SU8-Si) for PDMS replica molding. However, the complexity in the fabrication process, low feature reproducibility (master-to-master variability), silane toxicity, and short life span of these masters have been deterrents for using SU8-Si masters for the production of cell culture based PDMS microfluidic devices. While other techniques have demonstrated the ability to generate multiple devices from a single master, they often do not match the high feature resolution (∼0.1 μm) and low surface roughness that soft lithography masters offer. In this work, we developed a method to fabricate epoxy-based masters that allows for the replication of features with high fidelity directly from SU8-Si masters via their PDMS replicas. By this method, we show that we could obtain many epoxy based masters with equivalent features to a single SU8-Si master with a low feature variance of 1.54%. Favorable feature transfer resolutions were also obtained by using an appropriate Tg epoxy based system to ensure minimal shrinkage of features ranging in size from ∼100 μm to <10 μm in height. We further show that surface coating epoxy masters with Cr/Au lead to effective demolding and yield PDMS chambers that are suitable for long-term culturing of sensitive primary hippocampal neurons. Finally, we incorporated pillars within the Au-epoxy masters to eliminate the process of punching media reservoirs and thereby reducing substantial artefacts and wastage. |
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