A simple method for fabricating patterned curvilinear microstructures in poly(dimethylsiloxane) by selective wetting.

The fabrication of patterned microstructures in poly(dimethylsiloxane) (PDMS) is a prerequisite for soft lithography. Herein, curvilinear surface relief microstructures in PDMS are fabricated through a simple three-stage approach combining microcontact printing (μCP), selective surface wetting/dewetting and replica molding (REM). First, using an original PDMS stamp (first-generation stamp) with linear relief features, a chemical pattern on gold substrate is generated by μCP using hexadecanethiol (HDT) as an ink. Then, by a dip-coating process, an ordered polyethylene glycol (PEG) polymer-dot array forms on the HDT-patterned gold substrate. Finally, based on a REM process, the PEG-dot array on gold substrate is used to fabricate a second-generation PDMS stamp with microcavity array, and the second-generation PDMS stamp is used to generate third-generation PDMS stamp with microbump array. These fabricated new-generation stamps are utilized in μCP and in micromolding in capillaries (MIMIC), allowing the generation of surface micropatterns which cannot be obtained using the original PDMS stamp. The method will be useful in producing new-generation PDMS stamps, especially for those who want to use soft lithography in their studies but have no access to the microfabrication facilities.