Electrohydrodynamic Injection Micropump With Composite Gold and Single-Walled Carbon Nanotube Electrodes

The presence of microfeatures/nanofeatures with sharp asperities on the emitter electrodes of ion drag electrohydrodynamic (EHD) micropumps is likely to enhance the local electric field and charge injection significantly, and thus the pressure generation and flow rates. The objective of this paper is to investigate the performance of EHD micropumps with single-walled carbon nanotubes (SWCNT) on the emitter electrodes. The micropumps had 100 pairs of planar electrodes where the width of the emitter and collector electrodes was 20 and 40 $\mu \text{m}$ , respectively, with a cross-sectional domain of $100~\mu \textrm {m} \times 5$ mm. Two micropumps with interelectrode spacing of 120 and 40 $\mu \text{m}$ were tested with a smooth emitter surface, and where SWCNT were electrophoretically deposited on the emitter electrodes using HFE7100 as the working fluid. The threshold voltage for charge injection lowered by a factor of 3 and 1.4 for the two pumps with SWCNT on the emitter electrodes compared with the smooth electrode case. The corresponding static pressure head increased by a factor 5, while the flow rate at no external back pressure increased by a factor 3 for the pump with interelectrode spacing of 120 $\mu \text{m}$ . For the pump with interelectrode spacing of 40 $\mu \text{m}$ , a maximum static pressure of 4.7 kPa was achieved at 900 V with SWCNT on the emitter electrode. [2014-0308]