title: Microfluidic devices fabricated in poly(methyl methacrylate) using hot-embossing with integrated sampling capillary and fiber optics for fluorescence detection.
abstract: High-aspect-ratio microstructures have been prepared using hot-embossing techniques in poly(methyl methacrylate) (PMMA) from Ni-based molding dies prepared using LIGA (Lithographie, Galvanoformung, Abformung). Due to the small amount of mask undercutting associated with X-ray lithography and the high energy X-ray beam used during photoresist patterning, deep structures with sharp and smooth sidewalls have been prepared. The Ni-electroforms produced devices with minimal replication errors using hot-embossing at a turn around time of approximately 5 min per device. In addition, several different polymers (with different glass transition temperatures) could be effectively molded with these Ni-electroforms and many devices (>300) molded with the same master without any noticeable degradation. The PMMA devices consisted of deep and narrow channels for insertion of a capillary for the automated electrokinetic loading of sample into the microfluidic device and also, a pair of optical fibers for shuttling laser light to the detection zone and collecting the resulting emission for fluorescence analysis. Electrophoretic separations of double-stranded DNA ladders Phi X174 digested with Hae III) were performed with fluorescence detection accomplished using near-IR excitation. It was found that the narrow width of the channels did not contribute significantly to electrophoretic zone broadening and the plate numbers generated in the extended length separation channel allowed sorting of the 271/281 base pair fragments associated with this sizing ladder when electrophoresed in methylcellulose entangled polymer solutions. The dual fiber detector produced sub-attomole detection limits with the entire detector, including laser source, electronics and photon transducer, situated in a single box measuring 3'' x 10" x 14".
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: Shize
authors.initials: S
authors.lastname: Qi
authors.forename: Xuezhu
authors.initials: X
authors.lastname: Liu
authors.forename: Sean
authors.initials: S
authors.lastname: Ford
authors.forename: James
authors.initials: J
authors.lastname: Barrows
authors.forename: Gloria
authors.initials: G
authors.lastname: Thomas
authors.forename: Kevin
authors.initials: K
authors.lastname: Kelly
authors.forename: Andrew
authors.initials: A
authors.lastname: McCandless
authors.forename: Kun
authors.initials: K
authors.lastname: Lian
authors.forename: Jost
authors.initials: J
authors.lastname: Goettert
authors.forename: Steven A
authors.initials: SA
authors.lastname: Soper
mesh_terms: D004136:Dinitrobenzenes / Q000302:isolation & purification; D005336:Fiber Optic Technology; D044085:Microfluidics / Q000295:instrumentation*; D008855:Microscopy, Electron, Scanning; D055100:Optical Fibers; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D004136:Dinitrobenzenes; D019904:Polymethyl Methacrylate; C031536:dinitroaminophenol