Design, fabrication, and testing of an electrohydrodynamic ion-drag micropump

Abstract

This paper presents the design, fabrication, and testing of a novel electrohydrodynamic (EHD) ion-drag micropump. In order to maximize the electrical field gradients that are responsible for EHD pumping, we incorporated three-dimensional (3-D) triangular bumps of solder as part of the EHD electrodes. To form these bumps, Niobium was sputter-deposited onto a ceramic substrate, coated with photoresist, optically exposed and etched using a reactive ion etcher to define the electrode pattern. The substrate was then "dipped" into a molten solder pool. Since the solder adheres only to the metallic film, bumps of solder form on the electrodes, giving the electrodes a significant 3-D character. The overall dimensions of the micropump are 19 mm 32 mm 1.05 mm. Four different designs were fabricated and tested. Static pressure tests were performed with a 3M Thermal Fluid (HFE-7100) as the working fluid and the optimum design was identified. The results with the thermal fluid were highly promising and indicated a pumping head of up to 700 Pa at an applied voltage of 300 V. The experimental results for the four different designs show that the presence of the 3-D bump structures significantly improves the pumping performance. Also, a much better pumping performance was obtained with the micropump in which the emitter had a saw-tooth shape.

Recent advances in microscale pumping technologies: a review and evaluation

“…use ion drag as the force to drive the fluid. However, most of the micropumps in the literature referred to as being ion-drag pumps are injection-type EHD pumps (Darabi et al 2002, Seyed-Yagoobi 2005.…”

Acoustic Wave Based Microfluidics and Lab-on-a-Chip

“…The new trend is to develop non-mechanical or moving-part-free micropumps by utilizing electrokinetic forces and surface tension (or surface energy-related forces) such as the electroosmotic (EO) effect [5], electrophoresis (EP) [6], dielectrophoresis (DEP) [7,8], asymmetric electric field, electrowetting-on-dielectrics (EWOD) [9,10], electrostatic pumps [11,12] etc. Electrokinetic force based micropumps typically require electric/magnetic fields to mobilize ionic, or polarisable particles and species in a liquid which can drag the liquid through friction forces to form a continuous flow.…”

Improvement for Pressure Performance of Micro-EHD Pump with an Arrangement of Thin Cylindrical Electrodes

“…These advantages make them attractive for applications in micro cooling de-vices (6), (7) . Darabi et al (8) developed a series of planar comb finger electrodes which was three dimensional triangular bumps of solder. These electrodes were formed by the Niobium sputter-deposited on a ceramic substrate.…”