Surface microfluidics fabricated by superhydrophobic nanocomposite photoresist

Surface microfluidics can be of potential use in a variety of emerging applications, including biological and chemical analysis, cellular detection and manipulation, and high-throughput pharmaceutical screening. In comparison with the conventional closed-channel microfluidic system, surface microfluidics shows the distinct advantages of simple construction, direct fluidic connection, no cavitation or interphase obstruction, no optical barrier, and reusability. In this paper, we present the first surface microfluidic networks microfabricated by a single-step photolithographic process using a novel superhydrophobic photosensitive nanocomposite. The superhydrophobic photoresist incorporates PTFE nanoparticles into a photosensitive SU-8 matrix, in which superhydrophobicity (contact angle of 160°) is primarily contributed by the extremely low chemical energy and nanotopology of PTFE nanoparticles, while the SU-8 matrix offers photopatternability (lithographic resolution of 10 ¿m) and substrate adhesion. Furthermore, surface microfluidic pumps self-propelled by surface tension force have been fabricated and characterized to demonstrate the applicability of the novel nanocomposite material.