Study on the leftover of water to fluidic channels in the aqueous solution pumping by ECF jetting

This paper proposes the aqueous solution pumping system by ECF jetting and also focuses on the leftover of water to fluidic channels in the system. By utilizing non-mixing characteristics between oil and water, aqueous solution was successfully pumped out by the ECF jetting in the fabricated device. Although measured the flow rate was about 1μl/min at the applied voltage of 0.4 kV, the leftover of water to fluidic channels was observed over 0.2~0.3 kV. In order to solve this problem, we adopt two different approaches: (1) the surface-modification which is hydrophobization; (2) wider channel width (4.5 mm). The wider channel was not significantly effective in this time, while the hydrophobizatin was proved to increase boundary velocity about 172 %(27.8 mm/s) without the boundary break. This study clarifies that the combination of hydrophobization with the enlarged fluid channel has the potential to solve the problem of the water leftover.