Fabrication of a transparent structured superomniphobic surface using a multiple partial expose method

A novel approach which uses a multiple partial exposure method to fabricate a transparent structured superomniphobic surface with doubly re-entrant structures by using negative thick photoresist SU-8 as the material is proposed. By using gray-tone lithography, the doubly re-entrant structures can be formed only via a standard lithography process. The gray-tone lithography for fabricating the doubly re-entrant structures is achieved by depositing three appropriate thicknesses of Ti film on glass substrate that acts as the gray-tone mask. The proposed transparent surface with the doubly re-entrant structures successful suspend all the tested liquid even the completely wetting liquid, such as silicon oil with the surface tension of 20.9 mN/m. This approach provides a simple, flexible and low-cost solution for fabricating superomniphobic surface, and it also has the potential to integrate with either flexible or nonflexible substrate for different applications.