Spontaneous Particle Separation using Water-absorbing Nanoporous Ion Exchange Medium*

Manipulating mechanism of particle’s motion has been extensively studied for the sample preparation in microfluidic applications including diagnostics and biological analyses. However, most of conventional methods need additional external forces such as electric field or pressure and complicated channel designs, which demands highly complex fabrication processes. In this work, power-free manipulation of particle’s motion was suggested based on leveraging convective flow over diffusiophoresis near the water-absorbing nanoporous ion exchange medium, which was verified both by simulation and experiment. As a result, the direction of particle’s motion was controlled at one’s discretion, which led to the selective preconcentration of particles having different zeta potential. Also, design rule for maximizing the efficiency was suggested. Thus, this spontaneous particle separation method would be used as a key component in power-free lab on a chip applications.