3.1.2. ICEO micropumps
Bazant and Squires (Bazant & Squires, 2004; Todd M Squires & Bazant,
2004) suggested that the ICEO flow around polarizable obstacles has the
potential for liquid pumping in microchannels. Zhang et al. (Kai Zhang,
Tian, & Yu, 2012) numerically demonstrated that ICEO around
conducting/Janus cylinders immersed in a microchannel could be used for
efficient liquid pumping. Zhang et al. (Kai Zhang, Mi, & Sheng, 2013)
showed, in a numerical study, the capability of inducing the ICEO-based
pumping by employing a Janus cylinder in a T-shape microchannel. Nobari
et al. (Nobari, Movahed, Nourian, & Kazemi, 2016) used a similar
numerical strategy but using a conducting cylinder in a T-junction to
drive fluid flow in microchannels. Paustian et al. (Paustian et al.,
2014) used arrays of Janus micropillars to produce a pressure gradient
in a microchannel under the AC electric field. Furthermore, Wu et al.
(X. Wu, Ramiah Rajasekaran, & Martin, 2016) fabricated a conical-pore
polyethylene terephthalate conducting membrane immersed in an
electrolyte and used it for micro pumping in microfluidics under AC
electric field.
The ICEK micropumps introduced so far are categorized as ACEO micropumps
where the fluid velocity in the order of 0.1-2.5 mm/s has been reported
with applying DC electric signals (Lian & Wu, 2009; Yang Ng et al.,
2012). Huang et al. (C.-C. Huang et al., 2010) used ACEO micropumps
functioning under AC voltage (V<1.5 amplitude) to generate
fluid velocity in microchannels as high as 1.3 mm/s. Among the existing
ICEO micropumps, Nobari et al. (Nobari et al., 2016) demonstrated an
average fluid velocity of 1750 µm/s using DC electric field with E=
300V/cm strength in a microchannel. Altogether, both ACEO and ICEO
micropumps can produce a wide range of fluid velocities and are
exceptionally applicable for high-speed liquid pumping in microchannels.