An improvement has been made to couple isoelectric focusing (IEF) sample injection and capillary zone electrophoresis in an untreated fused silica capillary. Electroosmotic flow is efficiently prevented by simply using a rubber block at the outlet end of the capillary during IEF sample injection. The experimental conditions that affect the concentration effect are discussed. A concentration enh...

Track-etched polymer membranes are used to realize low-voltage electroosmotic (EO) pumps. The nanopores in polycarbonate (PC) and polyethylene terephthalate (PET) membranes were fabricated by the track-etching technique, the pore diameter was controlled in the range of 100 to 250 nm by adjusting the etching time. The results show that these EO pumps can provide high flow rates at low applied vo...

With the development of microfabrication technologies, microdevices are becoming more and more important to engineers examining microscale systems, especially those for chemical or biological analysis. Simulation of fluid flows through various microdevices will facilitate engineers to derive better design for controlling and handling fluid flows through microdevices. Present paper presents a nu...

Injection of liquid metal into a polydimethylsiloxane (PDMS) channel can provide a simple, cheap, and fast method to fabricate a noncontact electrode for micro electroosmotic flow (EOF) pumps. In this study, a multi-stage EOF pump using liquid metal noncontact electrodes was proposed and demonstrated for high-flow-velocity applications. To test the pumping performance of this EOF pump and measu...

A model to estimate the extent of intraparticle, or perfusive, electroosmotic flow (EOF) in CEC capillaries packed with macroporous particles has been developed. Nucleosil packings (d(p) = 7 microm) having nominal pore sizes of 500, 1000, and 4000 A were studied. Intraparticle pores ranging from 50 to 10000 A in diameter were partitioned into 995 intervals of 10 A. Using pore size distribution ...

Introduction Dispersion is a phenomenon that determines the resolution of several types of liquid phase chromatography, and is an important component of overall transport through electrokinetic flow systems. The severe dispersion of solute as it travels through a U-turn, for example, has attracted recent attention for this reason [1]. In “ideal” electroosmotic flow through uniform, straight cha...

Suspended microchannels suitable for electroosmotic flow were fabricated by coating and dissolving sacrificial polymer fibers created by a new technique which involves using a pressurized syringe loaded with solution to directly deposit filaments of solution on the substrate in a “connect-the-dots” style. Additionally, because both the stylus and syringe were controlled with an ultra-high preci...

Double-stranded DNA translocates through sufficiently large nanopores either in a linear, single-file fashion or in a folded hairpin conformation when captured somewhere along its length. We show that the folding state of DNA can be controlled by changing the electrolyte concentration, pH and PEG content of the measurement buffer. At 1m LiCl or 0.35m KCl in neutral pH, single-file translocation...

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...

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...