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.

[1]  G. Whitesides,et al.  Soft lithography in biology and biochemistry. , 2001, Annual review of biomedical engineering.

[2]  G. Whitesides,et al.  Rapid Prototyping of Microfluidic Systems in Poly(dimethylsiloxane). , 1998, Analytical chemistry.

[3]  V. Piotter,et al.  Injection molding and related techniques for fabrication of microstructures , 1997 .

[4]  Albert Folch,et al.  Gray-scale photolithography using microfluidic photomasks , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[5]  Lin Chen,et al.  (Review Article) High-Throughput DNA Analysis by Microchip Electrophoresis , 2004 .

[6]  G. Whitesides,et al.  Poly(dimethylsiloxane) as a material for fabricating microfluidic devices. , 2002, Accounts of chemical research.

[7]  Walter Bacher,et al.  Hot embossing - The molding technique for plastic microstructures , 1998 .

[8]  Holger Becker,et al.  Hot embossing as a method for the fabrication of polymer high aspect ratio structures , 2000 .

[9]  H. Becker,et al.  Polymer microfluidic devices. , 2002, Talanta.

[10]  Pun Pang Shiu,et al.  Rapid Fabrication of Micromolds for Polymeric Microfluidic Devices , 2007, 2007 Canadian Conference on Electrical and Computer Engineering.

[11]  G. Whitesides,et al.  Fabrication of microfluidic systems in poly(dimethylsiloxane) , 2000, Electrophoresis.

[12]  P. McNally,et al.  A comparative study of Pd/Sn/Au, Au/Ge/Au/Ni/Au, Au-Ge/Ni and Ni/Au-Ge/Ni ohmic contacts to n-GaAs , 1998 .

[13]  Chih-Yuan Chang,et al.  Rapid fabrication of ultraviolet-cured polymer microlens arrays by soft roller stamping process , 2007 .

[14]  Byeong Kwon Ju,et al.  Fabrication of round channels using the surface tension of PDMS and its application to a 3D serpentine mixer , 2007 .

[15]  Liwei Lin,et al.  Microplastic lens array fabricated by a hot intrusion process , 2004 .

[16]  P. Abgrall,et al.  Lab-on-chip technologies: making a microfluidic network and coupling it into a complete microsystem—a review , 2007 .

[17]  Jan G. Korvink,et al.  MEMS: A Practical Guide to Design, Analysis, and Applications , 2005 .

[18]  G. Palmskog,et al.  Silicon based replication technology of 3D-microstructures by conventional CD-injection molding techniques , 1997, Proceedings of International Solid State Sensors and Actuators Conference (Transducers '97).