Currently, there is very limited information on the electrophoretic behavior of particles at a liquid-liquid interface formed by two conducting liquid solutions. Here, electrophoretic velocities of polystyrene particles at a polyethylene glycol (PEG)-dextran (DEX) interface were investigated in this paper. Experimental results show that the particle at the interface moves in the opposite direction to the applied electric field, with a velocity much lower than that in the PEGrich phase and a litter larger than that in the DEX-rich phase. Similarly to the movement in Newtonian fluids, the velocity increases linearly with the increase in the applied electric field. Different to particle electrophoresis in Newtonian fluids, the velocities of the particles at the PEG-DEX interface increase linearly with the decrease in particle's diameters, implying a possible size-based particle differentiation at an interface.

Infections caused by antimicrobial resistance are a serious problem in the world. Currently, commercial devices for antimicrobial susceptibility testing and resistant bacteria identification are time‐consuming. There is an urgent need to develop fast and accurate methods, especially in the process of sample pretreatment. Electrokinetic (EK) is a family of electric‐field‐based kinetic phenomena of fluid or embedded objects, and EK applications have been found in various fields. In this paper, EK bacteria manipulation, including enrichment and separation, is reviewed. Focus is given to the rapid electric‐based minimum inhibitory concentration measurement. The future directions and major challenges in this field are also outlined.

At present, there is still limited report on the electrokinetic (EK) behavior of bioparticles at the interface of an aqueous two‐phase system. In this paper, the EK motion and viability assessment of live algae mixed with the NaClO treated dead algae were carried out at the interface formed by polyethylene glycol (PEG)‐rich phase and dextran (DEX)‐rich phase in a straight microchannel. The experimental results show that both the live and dead algae at the PEG–DEX interface migrate from the negative electrode to the positive electrode, and the EK velocity of live algae at the interface is slightly larger than that of the dead ones with similar diameters. For either live or dead algae, the EK velocity at the interface decreases with the increase in diameter. A size–velocity curve was used to evaluate the viability of the algae. As most of the microorganisms in ballast water are algae, the method in this paper provides a promising way to detect and evaluate the live microorganism in treated ballast water of a ship.