Induced-charge electrokinetics

Yasaman Daghighi and Dongqing Li, for the first time, experimentally illustrated these induced vortices around a 1.2 mm diameter carbon-steel sphere under the 40V/cm direct current (DC) external electric filed.

[1] Chenhui Peng et al.[3] also experimentally showed the patterns of electro-osmotic flow around an Au sphere when alternating current (AC) is involved (E=10mV/μm, f=1 kHz).

Electrokinetics here refers to a branch of science related to the motion and reaction of charged particles to the applied electric filed and its effects on its environment.

Such micro-mixers which are used for biochemical, medicine, biology applications has no mechanical parts and only use conducting surfaces to generate induced vortices to mix the different fluid streams.

In addition the induced vortices around the conducting surfaces in a microfluidic system can be used as a micro-valve, micro-actuator, micro-motor and micro-regulator to control the direction and manipulation.

visualized induced-charge electrokinetic flow pattern around a carbon-steel sphere (diameter = 1.2 mm). Four induced vortices are shown using fluorescent particles with a diameter of 1.90 μm. The DC electric field is applied from left to right and equals 40V/cm. The dashed line represents the particle boundary. The image is captured by TE2000-E Nikon microscope at t = 2s. [ 1 ]