Nanolithography on responsive materials

Inspired by the fascinating working process of living systems, materials that can respond to external stimuli (mechanical, chemical, optical changes in environmental conditions, etc.) are of enormous interest owing to their applications in a wide range of fields including microfluidic devices, drug delivery, tissue engineering, sensors and actuators. This review, while being non-exhaustive in literature, emphasizes the promising applications of responsive materials as building blocks of biomimetic devices, together with the description of lithographic techniques used to pattern stimuliresponsive polymers at microand nanoscale. The goal of these endeavors is to mimic biological systems by capitalizing on the prominent properties of “smart” materials. Herein, we briefly describe the principles of responsive behaviors on various polymer materials to external stimuli such as temperature, pH and light. We also introduce current techniques employed in fabricating structures on responsive polymers, such as photolithography, soft lithography, and atomic force microscope nanolithography. Emphasis is placed on a specific approach that generates nanostructures on a polymer that swells under local protonation. Overall, the review highlights the importance of responsive materials allowing fundamental understanding of material properties and practical applications.