Wall-less liquid pathways formed with three-dimensional microring arrays

This paper describes a method to construct microfluidic pathways without physical walls-wall-less microchannels. Compared to the previous wall-less microfluidics based on two-dimensional patterns, this method uses three-dimensional ring arrays and two immiscible liquids. The distant rings generate free-standing liquid pathways in order to minimize liquid surfaces contacted to solid walls. In the experimental study, we reduced the liquid-solid interface area per volume to 17.3 of that of the conventional microchannels with squared cross-sections. We envision that this aspect would be significant in micro/nano-fluidics, whose surface-area-to-volume ratio is extremely large.