Size-Tunable Micro-/Nanofluidic Channels Fabricated by Freezing Aqueous Sucrose

Upon freezing aqueous sucrose at temperatures higher than the eutectic point (-14 °C in this case), two phases, that is, ice and freeze concentrated solution (FCS), are spontaneously separated. FCS forms through-pore fluidic channels when thin ice septum is prepared from aqueous sucrose. Total FCS volume depends on temperature but is independent of the initial sucrose concentration. This allows us to control the size of the FCS channels simply by changing the initial sucrose concentration as long as temperature is kept constant. In this paper, we show that the size of the channel, which has a layered structure, can be controlled in a range from 50 nm to 3 μm. Thus, the FCS channel is suitable for size-sorting of micro- and nanoparticles. We discuss the size-sorting efficiency of the channel and demonstrate the separation of particles with different sizes.