Flexible Superhydrophobic Polymeric Surfaces with Micro-/Nanohybrid Structures Using Black Silicon

A novel way to fabricate flexible superhydrophobic PDMS surfaces using a microfabricated SU-8 template on black silicon is demonstrated. The SU-8 mold is fabricated on top of black silicon that has nanoscale features. The static water contact angle is generally 7 degrees larger on PDMS surfaces created on black silicon than on bare silicon, presumably due to the presence of nanoscale bumps. The highest static contact angle of 157 degrees and the lowest contact angle hysteresis of 3 degrees are obtained on molded PDMS surfaces with the cylindrical posts possessing a diameter of 40 mu m, spacing distance of 10 mu m, and height of greater than 15 mu m. The fabrication of superhydrophobic PDMS surfaces by means of black silicon is highly reproducible and may be suitable for many applications.