PMMA to SU-8 bonding for polymer based lab-on-a-chip systems with integrated optics

Brian Bilenberg Olsen, Theodor Nielsen, Bjarne Hans Clausen, Anders Kristensen

    Research output: Contribution to journalJournal articleResearchpeer-review


    We present an adhesive bonding technique developed for SU-8 based "lab-on-a-chip"- systems with integrated optical components. Microfluidic channels and optical components (e.g. wave-guides) are defined in SU-8 photoresist on a Pyrex glass substrate. The microfluidic channels are sealed by a second Pyrex substrate, bonded on top of the cross-linked SU-8 structure using an inter- mediate layer of 950K molecular weight poly-methylmethacrylate (PMMA). Due to a lower refractive index of PMMA, this bonding technique offers optical waveguiding in the SU-8 structures in combination with good sealing of the microfluidic channels. The bonding technique is investigated with respect to bonding temperature in the range of 50 - 150 degr. C and at bonding forces of 1000 N and 2000 N on a 4-inch wafer. A maximum bonding strength of 16 MPa is achieved for the PMMA to SU-8 bonding at a bonding temperature of 110 degr. C and at a bonding force of 2000 N. Furthermore 950K PMMA shows no tendency to flow into the microfluidic channels due to its high viscosity.
    Original languageEnglish
    JournalJournal of Micromechanics and Microengineering
    Issue number6
    Pages (from-to)814-818
    Publication statusPublished - 2004


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