Rapid fabrication of tooling for microfluidic devices via laser micromachining and hot embossing

This paper presents a new method for rapid fabrication of polymeric micromold masters for the manufacture of polymer microfluidic devices. The manufacturing method involves laser micromachining of the desired structure of microfluidic channels in a thin metallic sheet and then hot embossing the channel structure onto poly( methyl methacrylate) PMMA substrate to form the mold master. The channeled layer of the microfluidic device is then produced by pouring the polydimethylsiloxane ( PDMS) elastomer over the mold and curing it. The method is referred to as LHEM ( laser micromachining, hot embossing and molding). Polymers like PDMS are preferred over silicon as the material for building microfluidic devices because of their biocompatibility properties as well as because of their lower cost. The proposed manufacturing method involves fewer processing steps than the conventional soft lithography process and enables manufacture of non-rectangular channels in microfluidic devices. To test the method, a mold for a micro capillary electrophoresis microfluidic chip was fabricated. The experimental results confirmed that high quality (Ra 10 to 100 nm) molds can be fabricated quickly and inexpensively. Advantages and limitations of the proposed method are discussed in the concluding section of the paper.