SANE Approach To Soft Lithography

Researchers now have an easy way to use soft lithography to make many different patterns from the same master pattern (Nano Lett., DOI: 10.1021/nl102206x). Starting with a single master, Teri W. Odom and coworkers at Northwestern University used solvent-assisted nanoscale embossing (SANE) and inverse SANE (inSANE), respectively, to change the size and density of features in an array. With SANE, a poly­(di­methyl­silo­xane) mold is wetted with solvent and then placed in contact with a photoresist-coated substrate, such as silicon. The polymer mold is then swelled with different solvents to controllably create patterns with the same density as the master but with smaller features. With inSANE, the polymer mold is first wetted with photoresist and then placed in contact with a flexible substrate such as a thermoplastic. The patterned thermoplastic can be mechanically stretched or heated to increase or decrease the spacing between the features. These programmable methods will allow designers to create new masters with variable feature sizes and densities starting from a single original, the researchers note.