Microfluidic devices are currently being utilized in many types of BioMEMS and medical applications. In
these systems, the interaction between the surface and the biological specimen depends critically on surface properties.
The surface roughness and chemistry as well as the surface area to which the biomolecules or cells are exposed affect
this interaction. Modification of the surface of microfluidic channels can improve the operation of the device by
influencing the behavior of the biological specimens that are flowing through it. SU-8 is an epoxy-based, negative
photoresist that has been previously used to create covered channels. Once cured, it is both chemically and thermally
stable. It is also optically transparent above 360 nm, which allows optical measurements, including fluorescence
imaging, to be taken inside the channel. SU-8 microchannels have been fabricated with a porous layer on the sidewalls
by the photo-lithographic process, which is reproducible with precisely controlled channel dimensions. In order to attain
these porous sidewalls, no additional fabrication steps are required outside the standard photo-lithographic process. The
porosity of the sidewalls is a result of incomplete cross-linking of the polymer. The obtained porous surfaces can be
specially treated to provide conditions preferable for biological interactions. The porous layer increases the internal
surface area available on the sidewalls, which make these microfluidic channels preferable for biological applications.
This paper describes the details of the fabrication process and the experiments that verify the benefit of using SU-8
microchannels with porous sidewalls.