Wall-less Microfluidic Channels Using 3-dimemsional Ring Arrays

This paper presents a method to construct microfluidic channels without physical walls – wall-less microchannels. In order to minimize liquid surface areas contacted to solid walls, this method uses three dimensional ring arrays compared to the previous wall-less microfluidics based on two dimensional patterns of hydrophilic and hydrophobic areas. Thus, we can form free-standing liquid pathways surrounded by an immiscible liquid between distant rings in the ring arrays. In the experimental study, we reduced the liquid-solid interface areas per unit volume to 17.3% of that of the conventional microchannels with square cross-sections. We expect that this aspect would be important in micro/nano-fluidics, whose surface-area-to-volume ratio is extremely large.