This paper proposes a novel technique for fabricating microchannels in SU-8 by inserting optical-fibers as sacrificial moulds. The embedded circular microchannels, with inner diameters of 36, 80, and 125 μm (i.e., the diameters of optical-fibers), have been made successfully using a low-temperature fabrication process; where the SU-8 transparent negative-bone photo-resist is selected as the structure layer built in multilayers. Additionally, low-cost ultraviolet is applied as the exposure source to pattern the thin film photo-resist. Preliminary results show that the microchannels fabricated with the proposed technique have an average surface roughness (Ra) of the inner wall less than 10 nm and roundness deviation less than 7%. This paper also discusses the wetting behavior of the SU-8 surfaces before and after dipping in the hydrofluoric acid, and summarizes the relationship between the etching rate of sacrificial optical-fibers, etching temperature, concentration, and channel size. Finally, the etching rate of sacrificial optical-fibers vs. etching temperature subject to different concentrations and channel sizes is summarized and explained. This new fabrication technique of microchannel manufacture provides a new approach in selecting SU-8 for the structure material containing microchannels.
International journal of machine tools and manufacture 44(10), pp.1109-1114