Fabrication of perforated micro/nanopore membranes via a combination of nanoimprint lithography and pressed self-perfection process for size reduction.

Artificial membranes with perforated nanopores in defined locations provide an important biomimicking platform for sensing and analysis of biomolecules. This study presents a simple and flexible method to fabricate a freestanding polymer membrane with perforated micro- and nanopores using a combination of nanoimprint lithography (NIL) and pressed self-perfection (PSP) process. NIL was used to define initial pores of a few micrometers in diameter in the SU-8 membrane layer, which was followed by the PSP process where the patterned SU-8 membrane is pressed with a blank silicon wafer at an elevated temperature. This PSP process results in a lateral flow of the SU-8 resist and consequently reduces the pore size in the membrane. With this method, we have demonstrated fabrication of a SU-8 membrane with perforated pores down to approximately 300 nm in diameter. The results indicate that by employing a pore reduction process nanopore membranes can be manufactured without requirements of having a stamp with nanoscale structures and high aspect ratio imprinting with the stamp.