Abstract
Microfluidic devises fabricated by polymer MEMS (Micro Electro Mechanical Systems) technology have been widely used in interdisciplinary field study such as chemical and biochemistry experiments. Especially, the extension to include filtration membranes in microfluidic devices attracted biophysicists and bioengineers because filtration is an important step in bio-applications. Thus, the authors proposed the epoxy-based filtration membrane fabricated by only 3D photolithography process. This paper describes mechanical properties such as the elastic modulus and hardness of epoxy-based chemically-amplified negative resist, e.g. SU-8 or TMMF (hereafter photoresist) toward a design of nano-filtration membrane made of semi-cross-linked photoresist. So far, many dedicated experiments have been conducted on the characterization of mechanical properties of highly polymerized photoresist. However, the mechanical properties for semi-cross-linked photoresist have not been investigated, and not evaluated in terms of the cross-linked ratio which is the index of the membrane permeability. In the present experiments, a 30 gm thick dry-film type photoresist (TMMF, TOK Co., Ltd.) was employed for sample fabrication, and the indentation test was conducted by DUH-W201 (Shimadzu Cooperation). The elastic modulus for the membrane varied from 4.3 GPa to 4.9 GPa according to the cross-linked ratio of 0.5 to 0.75. Furthermore, it was confirmed that the mechanical properties have obviously correlated with the cross-linked ratio.
