Microfluidics: Functionality Integration for Proteomic Applications

Daria Petersen

    Research output: Book/ReportPh.D. thesis

    282 Downloads (Pure)


    Interest in miniaturization of chemical and biological analyses is growing. In this work, the design, fabrication and characterization of microfluidic analytical tools is studied. The focus is set on glass microchips for chemical analysis. The work consists of three parts:
    1) Design, fabrication and characterization of integrated microchips for protein processing with enhanced limit of detection (LOD);
    2) A novel bonding process of glass devices for miniaturized total analysis systems (µ-TAS);
    3) Design and fabrication of glass microchips with novel monolithically integrated electrospray ionization interface for capillary electrophoresis to mass spectrometry (CE-ESI-MS).
    Sample preconcentration, injection, separation, fluorescence labeling, postcolumn dilution (destaining) for signal enhancement and detection of proteins are combined and optimized in a single glass microdevice. On-column as well as post-column non-covalent protein labeling strategies are demonstrated to be compatible with protein preconcentration using a sol-gel filter followed by capillary sieving electrophoresis (CSE) as a separation method. This is the first demonstration of on-chip protein preconcentration integrated with on-chip non-covalent labeling. It is demonstrated that post-column labeling and dilution (destaining) performed simultaneously in a single step result in better separation efficiency and limits of detection similar to these compared to on-column labeling combined with destaining. The novel bonding process for glass chips involves a sputtered-on polysilicon layer which is employed both as an adhesion layer for the etch mask and as an intermediate layer for field-assisted bonding, thus reducing the number of microfabrication steps. A mechanism of field-assisted anodic bonding is discussed. This bonding scheme is found to be superior to direct bonding methods such as high temperature fusion bonding in terms of process yield, and the relatively low bonding temperature (~ 350 ºC) makes it suitable for packaging of microsystems having integrated layers with different thermal expansion coefficients or low melting points. This novel fabrication process is used to fabricate CE glass chips with an electrospray needle for capillary electrophoresis coupled by electrospray ionization to mass spectrometry (CE-ESI-MS). The ESI interface is designed and fabricated in conjunction with a CE-separation channel. Microfabrication procedures are developed and optimized to create a zero dead volume monolithically integrated electrospray needle.
    Original languageEnglish
    Place of PublicationKgs. Lyngby
    PublisherTechnical University of Denmark
    Number of pages151
    Publication statusPublished - Nov 2006

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