[Show abstract][Hide abstract] ABSTRACT: In this paper we describe the spatial surface chemical modification of
bonded microchannels through the integration of microplasmas into a
microfluidic chip (MMC). The composite MMC comprises an array of
precisely aligned electrodes surrounding the gas/fluid microchannel.
Pairs of electrodes are used to locally ignite microplasmas inside the
microchannel. Microplasmas, comprising geometrically confined
microscopic electrically-driven gas discharges, are used to spatially
functionalise the walls of the microchannels with proteins and enzymes
down to scale lengths of 300 μm inside 50 μm-wide microchannels.
Microchannels in poly(dimethylsiloxane) (PDMS) or glass were used in
this study. Protein specifically adsorbed on to the regions inside the
PDMS microchannel that were directly exposed to the microplasma. Glass
microchannels required pre-functionalisation to enable the spatial
patterning of protein. Firstly, the microchannel wall was functionalised
with a protein adhesion layer, 3-aminopropyl-triethoxysilane (APTES),
and secondly, a protein blocking agent (bovine serum albumin, BSA) was
adsorbed onto APTES. The functionalised microchannel wall was then
treated with an array of spatially localised microplasmas that reduced
the blocking capability of the BSA in the region that had been exposed
to the plasma. This enabled the functionalisation of the microchannel
with an array of spatially separated protein. As an alternative we
demonstrated the feasibility of depositing functional thin films inside
the MMC by spatially plasma depositing acrylic acid and 1,7-octadiene
within the microchannel. This new MMC technology enables the surface
chemistry of microchannels to be engineered with precision, which is
expected to broaden the scope of lab-on-a-chip type applications.
[Show abstract][Hide abstract] ABSTRACT: A rapid, high-precision method for localised plasma-treatment of bonded PDMS microchannels is demonstrated. Patterned electrodes were prepared by injection of molten gallium into preformed microchannel guides. The electrode guides were prepared without any additional fabrication steps compared to conventional microchannel fabrication. Alignment of the "injected" electrodes is precisely controlled by the photomask design, rather than positioning accuracy of alignment tools. Surface modification is detected using a fluorescent dye (Rhodamine B), revealing a well-defined micropattern with regions less than 100 µm along the length of the microchannel.
Lab on a Chip 10/2010; 11(3):541-4. · 5.70 Impact Factor