AC Electrokinetics of Conducting Micro- and Nano- Particles

“AC Electrokinetics of conducting micro- and nano- particles”

by Antonio Ramos

Departamento de Electrónica y Electromagnetismo, Universidad Sevilla, Spain

We examine the motion induced on conducting micro- and nano- particles suspended in electrolyte by AC electric fields. Specifically, we study the translational motion (dielectrophoresis) and the rotational motion (electrorotation or electro-orientation) of conducting spheres and rods. Because the particles are in electrolyte, the applied AC electric fields induce charge in the electrical double layer at the particle-electrolyte interface. Particle motion is due to both the electric field interaction with the induced dipole on the particle and the induced-charge electro-osmotic flow around the particle. The importance of the characteristic RC time to charge the double layer capacitance through the electrolyte resistance is highlighted. Experimental measurements of AC Electrokinetics of metal particles are presented and compared with actual theory, providing a comprehensive study of the relative importance between particle motion due to electrical forces applied directly on the particle (force and torque on induced dipole) and electrical forces applied on the liquid and transmitted to the particle by viscous forces (induced-charge electro-phoresis).

 

Figure. Electrorotation (left) and Electro-orientation (right) spectra of metal nanowires. Continuous lines come from dipole theory. (See refs. 1 and 2 for details).

References

1.       JJ Arcenegui, P García-Sánchez, H Morgan, A Ramos, Phys Rev E, 88, 033025 (2013)

2.       JJ Arcenegui, P García-Sánchez, H Morgan, A Ramos, Phys Rev E, 88, 063018 (2013)