title: Design, fabrication and characterization of monolithic embedded parylene microchannels in silicon substrate.
abstract: This paper presents a novel channel fabrication technology of bulk-micromachined monolithic embedded polymer channels in silicon substrate. The fabrication process favorably obviates the need for sacrificial materials in surface-micromachined channels and wafer-bonding in conventional bulk-micromachined channels. Single-layer-deposited parylene C (poly-para-xylylene C) is selected as a structural material in the microfabricated channels/columns to conduct life science research. High pressure capacity can be obtained in these channels by the assistance of silicon substrate support to meet the needs of high-pressure loading conditions in microfluidic applications. The fabrication technology is completely compatible with further lithographic CMOS/MEMS processes, which enables the fabricated embedded structures to be totally integrated with on-chip micro/nano-sensors/actuators/structures for miniaturized lab-on-a-chip systems. An exemplary process was described to show the feasibility of combining bulk micromachining and surface micromachining techniques in process integration. Embedded channels in versatile cross-section profile designs have been fabricated and characterized to demonstrate their capabilities for various applications. A quasi-hemi-circular-shaped embedded parylene channel has been fabricated and verified to withstand inner pressure loadings higher than 1000 psi without failure for micro-high performance liquid chromatography (microHPLC) analysis. Fabrication of a high-aspect-ratio (internal channel height/internal channel width, greater than 20) quasi-rectangular-shaped embedded parylene channel has also been presented and characterized. Its implementation in a single-mask spiral parylene column longer than 1.1 m in a 3.3 mm x 3.3 mm square size on a chip has been demonstrated for prospective micro-gas chromatography (microGC) and high-density, high-efficiency separations. This proposed monolithic embedded channel technology can be extensively implemented to fabricate microchannels/columns in high-pressure microfluidics and high-performance/high-throughput chip-based micro total analysis systems (microTAS).
authors.affiliation: Department of Electrical Engineering, Divison of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125, USA. pjchen@mems.caltech.edu
authors.forename: Po-Jui
authors.initials: PJ
authors.lastname: Chen
authors.forename: Chi-Yuan
authors.initials: CY
authors.lastname: Shih
authors.forename: Yu-Chong
authors.initials: YC
authors.lastname: Tai
mesh_terms: D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D011108:Polymers / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D014992:Xylenes / Q000737:chemistry*
chemical_list: D011108:Polymers; D014992:Xylenes; C011055:parylene; D012825:Silicon