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Issue 1, 2014
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SU-8 bonding protocol for the fabrication of microfluidic devices dedicated to FTIR microspectroscopy of live cells

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Abstract

Here we present a new bonding protocol for SU-8 negative tone photoresist that exploits the chemical modifications induced in the resin by exposure to 254 nm (UVC) light. Fourier Transform Infrared microspectroscopy (μ-FTIR) was used to carry out a thorough study on the chemical processes and modifications occurring within the epoxy resin by exposure to 365 nm and 254 nm light. In particular, we established that UVC light promotes the opening of the epoxy rings bypassing the post-exposure bake. The possibility to promote a further activation of the resin, already patterned with standard UV lithography, was exploited to produce closed microfluidic devices. Specifically, we were able to fabricate fluidic chips, characterized by broadband transparency from mid-IR to UV and long term stability in continuous flow conditions. CaF2 was used as substrate, coated by sputtering with a nanometric silicon film, in order to make surface properties of this material more suitable for standard fabrication processes with respect to the original substrate. The fabricated microfluidic chips were used to study by μ-FTIR the biochemical response of live breast cancer MCF-7 cells to osmotic stress and their subsequent lysis induced by the injection of deionized water in the device. μ-FTIR analyses detected fast changes in protein, lipid and nucleic acid content as well as cytosol acidification.

Graphical abstract: SU-8 bonding protocol for the fabrication of microfluidic devices dedicated to FTIR microspectroscopy of live cells

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Publication details

The article was received on 26 Jul 2013, accepted on 30 Sep 2013 and first published on 30 Sep 2013


Article type: Paper
DOI: 10.1039/C3LC50878A
Citation: Lab Chip, 2014,14, 210-218
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    SU-8 bonding protocol for the fabrication of microfluidic devices dedicated to FTIR microspectroscopy of live cells

    E. Mitri, G. Birarda, L. Vaccari, S. Kenig, M. Tormen and G. Grenci, Lab Chip, 2014, 14, 210
    DOI: 10.1039/C3LC50878A

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