Abstract
Ionic responses in micro/nanofluidic channels have attracted significant attention in various research fields, where ionic currents have an important role to modulate electrophoretic behavior of electrically charged molecules. In order to manipulate target molecules, flow fields have to be accurately controlled. Some problems, however, have remained to figure out such difficulties. In this study, we have developed an experimental system to investigate a relationship between the spatial and temporal scales of ionic current responses. Using a pair of conical shaped electrodes to variably change the gap distance, we can measure unsteady ionic responses systematically and analyze the scales of phenomena. Based on a previous theoretical study, the validity of experimental results is confirmed. As a consequence, ionic responses that consist of electrophoresis and diffusion are revealed from both experimental and theoretical aspects.
