The osmotic flow is fundamental to free-membrane micro/nanofluidic devices to control the liquid transport, desalination process and biological membrane by using temperature, electrical potential and salt concentration gradients. To obtain the high efficiency of osmotic flow, fluidic resistance should be reduced and the liquid-air interface is one of the methods for decreasing fluidic resistance. Recently, in order to enhance the osmotic flow, a superhydrophobic surface with an extremely low fluidic resistance has been theoretically investigated, but there has been little experimental analysis.
MEL develops nano-structured superhydrophobic microfluidic devices by using surface energy modification and photolithography process. To observe the enhanced osmotic flow, we use salt concentration gradient which occurs osmotic pressure with different types of salts (LiCl and KCl).