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".

Rapid PCR in a continuous flow device

“…A mold insert for hot embossing was produced using the LIGA process. [43][44][45] The mold insert was used to hot emboss several microfluidic channels in polycarbonate substrates (Goodfellow, UK) using a PHI (City of Industry, CA) press equipped with a vacuum chamber. Inspection of SEM micrographs indicated that the sidewalls of the embossed channels were straight and smooth and contained the insert-defined channel width and height indicating minimal replication errors.…”

Microfluidic sensing: state of the art fabrication and detection techniques

“…Current methods for fabrication of microfluidic devices include prototyping techniques (includes hot embossing, 55,56 injection molding, 57,58 and soft lithography 59 ) and direct fabrication techniques such as laser photoablation or laser micromachining, 60 photolithography/optical lithography 61 and x-ray lithography 62 ( Figs. 1 and 2).…”

Evaluation of Different Nonspecific Binding Blocking Agents Deposited Inside Poly(methyl methacrylate) Microfluidic Flow-Cells

“…In that regard, a good coating needs not only to effectively suppress the non-specific adsorption of biomolecules but also must show stability under prolonged rinsing and immersing with buffer which is commonly required in. This is believed to be useful for the design and development of PMMA-based microfluidic immunosensor and biosensors [22][23][24][25][26]. …”