Rapid and inexpensive method for fabrication of multi-material multi-layer microfluidic devices

The vast majority of polymeric microfluidic devices that have been developed so far feature the use of a single or two material of construction. This is mainly due to the difficulty in integrating multiple materials into these devices using conventional microfabrication techniques such as photolithography, soft lithography or hot embossing either due to mismatch in the processing conditions or due to poor bonding between the materials. Nevertheless, integration of multiple materials into microfluidic devices can enable new and interesting functionalities. In this study, a rapid and inexpensive fabrication technique has been developed in which xurography and cold lamination methods were combined to create microfluidic devices integrating different materials. Materials with different surface energy and properties were used to provide unique functionality. This functionality was shown by fabricating channels that can have varying capillary filling rates from 33 mm s(-1) to 24 mm s(-1) by changing the surface energy of the materials that constitute the top and bottom of the microchannels. Similarly, highly robust and integrated passive valves that were able to stop capillary filling was also demonstrated by combining patterned features of hydrophobic and hydrophilic surfaces. Integration of thin elastomeric membrane with thermoplastic materials was also demonstrated by fabrication an active pneumatic valve that was capable of stopping capillary flow. Finally, this method of integration of multiple materials, was also used to integrate hydrogels into microfluidic devices in a parallel manner and to confine it locally in specific regions.