Step-and-repeat stamping method for the generation of large-area microscale wrinkle patterns

Abstract

We proposed a step-and-repeat stamping method for fabricating large-area microscale wrinkles with a Polydimethylsiloxane (PDMS) mold. First, an original wrinkle pattern was created by controlling the thickness of a photocurable resin (NOA-68T), which was exposed to ultraviolet light within a short time and then fully cured at a temperature of 30 °C for approximately 10 h. Microscale wrinkles could be obtained after two successive steps. PDMS was cast in a container with the fabricated wrinkle pattern and then cured at 75 °C for 2 h. A PDMS mold with a wrinkle pattern was then obtained after separating the master wrinkle pattern from the cured PDMS. A Selfassembled monolayer (SAM) was coated onto the surface of the PDMS mold to realize effective wrinkle replication on PDMS. Finally, the wrinkle pattern was stamped directly onto the large-area substrate within a significantly reduced processing time. The contact angles on the wrinkled surfaces of the resin layer and the PDMS mold were 47.8 % and 36.3 % larger than those on the corresponding flat surfaces, respectively. The proposed simple and cost-effective method of generating a large wrinkled area can be applied to surface modification in various engineering applications, including cell culture, microfluidics, biomedical devices, and flexible electronics.