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Effect of a CNT based composite micromold on the replication fidelity during the microfabrication of polymeric microfluidic devices

Jena, R. K., Yue, C. Y., Yun, K. X.
RSC advances 2014 v.4 no.24 pp. 12448-12456
composite polymers, epoxides, friction, glass, injection molding, nanocomposites, olefin, roughness, temperature
In recent years, polymer based microfluidic devices have become more widespread with the driving force being the development of inexpensive disposable analytical devices. Hot embossing and injection moulding are the two promising techniques that are widely used for micro-fabrication of polymeric substrates because identical devices can be mass produced using a master/mold. However, the major problem with these techniques is the time and expense needed to produce a stamping tool (mold) which can withstand the temperature and stress of the fabrication process over multiple cycles. To overcome this problem, we have developed an epoxy toughened nanocomposite mold material, which is relatively inexpensive compared to the commonly used metallic glass mold material. Our molds can be produced with ease, and are sufficiently durable to withstand multiple embossing cycles. Moreover, compared to other mold materials, very high aspect ratio microchannels can be replicated. We have characterized the morphological, physical and thermomechanical properties of this new nanocomposite mold material including its surface morphology, roughness and friction coefficient. Finally, the performance of the nanocomposite mold to fabricate microdevices using a cyclic olefin copolymer (COC) by the hot embossing and injection molding techniques was assessed. This mold material was found to be suitable for fabricating polymeric microdevices with high channel integrity.