Prototyping of microfluidic systems with integrated ... - DTU Nanotech

Abstract
In recent years, the use of polymer materials in the field of microfluidic
systems and so-called ’lab-on-a-chip’ systems has increased. Silicon,
the material traditionally used for the fabrication of such systems, is
not compatible with for instance blood or harsh chemicals, while many
polymers have the desired properties. A number of standard polymers
like poly(methyl methacrylate) and polydimethylsiloxane have been
investigated, but also new polymer types with e.g. superior optical or
chemical properties have emerged in microfluidic research.
The lab-on-a-chip systems integrate fluidic handling and measurement
on a single chip, and both optical and electronical components can
be embedded. For polymer microsystems, integration of optical waveguides
can be achieved by structuring polymers with different refractive
indices.
This thesis treats aspects of prototyping and fabrication of microfluidic
systems in polymers, mainly in the cyclic olefin copolymer Topas.
This relatively new polymer is resistant to a large number of chemicals
and to strong acids, making it suited for microfluidic systems used e.g.
for long term waste water monitoring. The high refractive index and
other good optical properties makes it suited for integrated optics in
microfluidic systems. Also, the engineerable glass transition temperature
is an advantage, when making single-polymer systems.
During the project existing fabrication methods have been adapted
or improved for use with Topas, so that a number of tools for rapid
prototyping of this polymer is now available. These tools include:
• Micro milling of fluidic channels and optical waveguides with
dimensions down to 25 µm.
• Spin coating of polymer layers on polymer substrates with a thickness
from 100 nm to 20 µm. The spin coat layers act as a glue for
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