FABRICATION OF PERFORATED CONICAL NANOPORES IN FREESTANDING POLYMER MEMBRANES USING NANOIMPRINT LITHOGRAPHY AND PRESSED SELF-PERFECTION METHOD

摘要

Nanopores have proven to be an important sensing element in biosensors to detect and analyze single biomolecules such as DNAs RNAs or proteins. The charged biomolecules are driven by an electric field and detected as transient current blocks associated with their translocation through the pores. While protein nanopores such as alpha-hemolysin and MspA protein nanopores embedded within a lipid bilayer membrane [1] promise to be a rapid sensitive and label-free sensing paradigm their duration of usage is too short to perform repetitive experiments due to the mechanical instability of the lipid bilayer. A variety of methods have been developed to prepare synthetic nanopores which can substrate for protein nanopores including a direct milling with a focused high-energy electron or ion beam in insulating substrates an ion track etching in polymer substrates and an anodizing in aluminum substrates. However those methods do not allow for control over both the size and location of pores and the high yield of production. We have previously developed a flexible and high throughput method using all parallel processes to produce freestanding polymer membranes with perforated pores down to sub-micrometer in diameter by a combination of nanoimprint lithography and a sacrificial layer technique [2]. The fabricated membrane can be easily integrated within a microfluidic system for in-situ formation of lipid bilayers at the micropores. However it was difficult to reduce the pore size down to nanometer scale with this method because a stamp with extremely high aspect ratio and imprinting with this stamp are required in order to achieve high mechanical strength for the polymer membrane. In this study we will present fabrication of perforated conical nanopores in freestanding polymer membranes by using an imprint lithography combined with pressed self-perfection method [3] and sacrificial layer technique.