Evaluation of micromilled metal mold masters for the replication of microchip electrophoresis devices
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High-precision micromilling was assessed as a tool for the rapid fabrication of mold masters for replicating microchip devices in thermoplastics. As an example, microchip electrophoresis devices were hot embossed in poly(methylmethacrylate) (PMMA) from brass masters fabricated via micromilling. Specifically, sidewall roughness and milling topology limitations were investigated. Numerical simulations were performed to determine the effects of additional volumes present on injection plugs (i.e., shape, size, concentration profiles) due to curvature of the corners produced by micromilling. Elongation of the plug was not dramatic (< 20%) for injection crosses with radii of curvatures to channel width ratios less than 0.5. Use of stronger pinching potentials, as compared to sharp-corner injectors, were necessary in order to obtain short sample plugs. The sidewalls of the polymer microstructures were characterized by a maximum average roughness of 115 nm and mean peak height of 290 nm. Sidewall roughness had insignificant effects on the bulk EOF as it was statistically the same for PMMA microchannels with different aspect ratios compared to LiGA-prepared devices with a value of ca. 3.7 × 10−4 cm2/(V s). PMMA microchip electrophoresis devices were used for the separation of pUC19 Sau3AI double-stranded DNA. The plate numbers achieved in the micromilled-based chips exceeded 1 million/m and were comparable to the plate numbers obtained for the LiGA-prepared devices of similar geometry.
KeywordsMicromilling Hot-embossing Microchip electrophoresis Polymer microfluidics
The authors gratefully acknowledge the financial support of the National Institutes of Health (R24-EB0002115) and National Science Foundation (EPS-0346411). The authors would also like to thank Dr. Varshni Signh of the Center for Advanced Microstructures and Devices (CAMD, LSU) for help with obtaining SEM images.
- Blom MT, Hasselbrink EF, Wensink H, Van Den Berg A (2001) Solute dispersion by electroosmotic flow in nonuniform microfluidic channels. Micro Total Analysis Systems 2001. In: Proceedings mTAS 2001 Symposium, 5th, Monterey, CA, United States, Oct 21–25, 2001, pp 615–616Google Scholar
- Boone TD, Fan ZH, Hooper HH, Ricco AJ, Tan H, Williams SJ (2002) Plastic advances microfluidic devices. Anal Chem 74(3):78A–86AGoogle Scholar
- Ehrfeld W, Lehr H, Michel F, Wolf A, Gruber H-P, Bertholds A (1996) Micro electro discharge machining as a technology in micromachining. In: Proceedings of SPIE—the international society for optical engineering 2879 (Micromachining and Microfabrication Process Technology II), pp 332–337Google Scholar
- Madou M, Lee LJ, Koelling KW, Daunert S, Lai S, Koh CG, Juang Y, Yu L, Lu Y (2001) Design and fabrication of polymer microfluidic platforms for biomedical applications. ANTEC-SPE 59, pp 2534–2538Google Scholar
- Qi S, Liu X, Ford S, Barrows J, Thomas G, Kelly K, McCandless A, Lian K, Goettert J, Soper SA (2002) Microfluidic devices fabricated in poly(methyl methacrylate) using hot-embossing with integrated sampling capillary and fiber optics for fluorescence detection. Lab Chip 2(2):88–95CrossRefGoogle Scholar