Electrically induced formation of uncapped, hollow polymeric microstructures

Uncapped, hollow polymeric microstructures were fabricated on a silicon substrate using electric field induced stretching and detachment. Initially, square or cylinder microposts were generated using a solvent-assisted capillary molding technique, and a featureless electrode mask was positioned on the top of the microstructure with spacers maintaining an air gap (similar to 20 mu m). Upon exposure to an external electric field (1.0-3.0 V mu m(-1)), the hollow microstructures were destabilized and stretched by the well-known electrohydrodynamic instability, resulting in contact of the top polymer surface with the mask. Subsequently, detachment of the capping layer occurred upon removal of the mask due to larger adhesion forces at the polymer/mask interface than cohesion forces of the polymer. These hollow microstructures were tested to capture the budding yeast, Saccharomyces cerevisiae, for shear protection.This work was supported by the Nanoscopia Center of Excellence at Hanyang University and in part by the Micro Thermal System Research Center at Seoul National University and the Korea Institute of Machinery & Materials (KIMM)