Three dimensional gels of aligned collagen fibers were patterned in vitro using microfluidic channels. Collagen fiber orientation plays an important role in cell signaling for many tissues in vivo, but alignment has been difficult to realize in vitro. For microfluidic collagen fiber alignment, collagen solution was allowed to polymerize inside polydimethyl siloxane (PDMS) channels ranging from 10-400 microm in width. Collagen fiber orientation increased with smaller channel width, averaging 12+/-6 degrees from parallel for channels between 10 and 100 microm in width. In these channels 20-40% of the fibers were within 5 degrees of the channel axis. Bovine aortic endothelial cells expressing GFP-tubulin were cultured on aligned collagen substrate and found to stretch in the direction of the fibers. The use of artificially aligned collagen gels could be applied to the study of cell movement, signaling, growth, and differentiation.

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