Experiments are described on the electrophoretic mobility of a single isolated colloid and the electroosmotic response of the surrounding medium. For that optical tweezers are employed which enable one to trap a particle without any mechanical contact and to measure its position and the forces acting on it with high resolution (±2 nm, ±200 fN). In a custom-made microfluidic cell, the two effect...

ζ-potentials of entities such as cells and synaptosomes have been determined, but ζ of brain tissue has never been measured. Electroosmotic flow, and the resulting transport of neuroactive substances, would result from naturally occurring and experimentally or clinically induced electric fields if ζ is significant. We have developed a simple method for determining ζ in tissue. An electric field...

Dynamic characteristics of electroosmosis of a typical non-Newtonian liquid in a rectangular microchannel are investigated by using numerical simulations. The non-Newtonian behavior of liquids is assumed to obey the famous power-law model and then the mathematical model is solved numerically by using the finite element method. The results indicate that the non-Newtonian effect produces some not...

The agro-industrial sludge, tested in this work, comes from a biscuit factory (France). Initially, it contains 3 % w/w of dry matter. The actual treatment by centrifugation dewaters it to 13 % w/w of dry matter. Electroosmotic dewatering under pressure (EOD) was investigated, as an alternative technology of mechanical treatment, to improve dewatering. This electrical treatment efficiency depend...

Among the microfluidic separation methods, hydrodynamic spreading is a simple and high-throughput continuous separation technique based on the difference in size. However, it is difficult to adjust tiny pressure differences accurately in microfluidic devices. In this study, a combination of electroosmotic flow (EOF) and hydrodynamic flow spreading was employed to tune the size separation of par...

Non-steady-state processes in capillary electrophoresis can be estimated by applying a steady-state mathematical model. Calculations with a steady-state model indicate that in capillary electrophoresis, moving boundary zones can originate from discontinuities in the concentration of the co-ions and/or the pH of the background electrolyte. Calculations showed that cationic moving boundaries with...

The increasing heat generation rates in VLSI circuits motivate research on compact cooling technologies with low thermal resistance. This paper develops a closed-loop two-phase microchannel cooling system using electroosmotic pumping for the working fluid. The design, fabrication, and open-loop performance of the heat exchanger and pump are summarized. The silicon heat exchanger, which attaches...

Here, we construct an open-channel on-chip electroosmotic pump capable of generating pressures up to ∼170 bar and flow rates up to ∼500 nL/min, adequate for high performance liquid chromatographic (HPLC) separations. A great feature of this pump is that a number of its basic pump units can be connected in series to enhance its pumping power; the output pressure is directly proportional to the n...

To quantify the flow of small uncharged molecules into and across nanopores, one often uses ion currents. The respective ion-current fluctuations caused by the presence of the analyte make it possible to draw some conclusions about the direction and magnitude of the analyte flow. However, often this flow appears to be asymmetric with respect to the applied voltage. As a possible reason for this...

Microfluidics, an enabling and emerging technology in cancer metastasis research, has yet to be applied in the analysis of individual cells taken directly from patient carcinomas. Accordingly, we have developed an integrated microfluidic methodology to label, dissociate, transport and detect patient-derived tumour cells. Following on-chip cold perfusion of tissue with antibody and enzymes, fluo...