Step-and-Repeat UV Nanoimprint Using PFP Gas for Realizing Microneedle Array with Jagged Tip Shape Bioinspired by Mosquito

A microneedle with serrated tip mimicking mosquito proboscis is effective for reducing the pain. A microneedle having high aspect ratio of over 10, e.g., 100 µm in diameter and 1,000 µm (1 mm) in length, was successfully fabricated using UV nanoimprint method. The jagged shape is difficult to release both from the master and from the mold. To address this, applying a polydimethylsiloxane (PDMS) mold to UV nanoimprint was proposed, which is effective for releasing the curved shape thanks to the mold flexibility. To further improve the releasability, pentafuluoropropane (PFP) gas was employed. Finally, the step-and-repeat method was applied for increasing the number of needles, realizing the array type microneedles.