Electrokinetic Dispensing

Electrokinetic dispensing is a method using electroosmotic pumping to inject a small quantity of... 

Electrokinetic Dispensing, Fig. 1 Schematic diagram of a commonly used cross-linked microchannel for elec-trokinetic dispensing... 

For an incompressible, Newtonian liquid flow, which is common for most electrokinetic dispensing applications, the flow field is described by the continuity equation... 

As mentioned above, electrokinetic dispensing normally employs a straight cross-linked microchannel to dispense a small amount of... 

Fu et al. [4] presented a numerical model for electrokinetic dispensing in microfluidic chips where simple cross, double-T, and triple-T configurations were considered. In this model, the Nemst-Planck equation was employed to describe the ionic concentration instead of the Boltzmann distribution, which is a more general approach. The model was numerically solved using the finite difference method where the artificial compressibility method was employed to deal with the pressure term in the N-S equation. It is found that the applied potentials play an important role in crnitroUing the loaded and dispensed sample shape. The unique feature of this study is the concept of the multi-T injection system which can function as a simple cross, double-T, or triple-T injectimi unit. Their numerical results agreed well with their experimental results. More injection techniques were also developed by the same group later. 

Nanofluidic chips have attracted increasing attention recently however, the fluid flow in such a small scale might not be well described by the traditional Navier-Stokes equation, which has been used for most numerical models for electrokinetic dispensing. Therefore, the development of numerical models for electrokinetic dispensing in nanofluidic chips will be of great importance for the design and control of such small-scale chips. In these models, other theories such as molecular dynamics might be used to describe the flow field. 

Since electrophoresis can differentiate charged particles with great selectivity on the basis of their electrophoretic mobility, it has found extensive application in separation systems used in the biomedical industry, such as capillary electrophoresis [2], gel electrophoresis, and electrochromatography [3]. With the rapid development of modem microfluidic technology, electrophoresis has been successfully applied in the manipulation of microparticles and biological cells, by techniques such as isoelectric focusing [4] and electrokinetic dispensing [5]. 

Regnier FE, He B, Lin S, Busse J (1999) Chromatography and electrophoresis on chips critical elements of future integrated, microfluidic analytical systems for life science. Trends Biotechnol 17 101-106 Cabrera CR, Yager P (2001) Continuous concentration of bacteria in a microfluidic flow cell using electrokinetic techniques. Electrophoresis 22(2) 355-362 5. Xuan X, Li D (2005) Focused electrophoretic motion and selected electrokinetic dispensing of particles and cells in cross-microchannels. Electrophoresis 26(18) 3552-3560... 

Electrical Double Layer Interaction Electrical Pumps Electrochemical Techniques Electrokinetic Dispensing... 

Electrokinetic dispensing is a method using electroosmotic punqting to inject a small quantity of samples, the size and concentration of which can be controlled by manipulating applied electrical potential fields, modifying channel surfaces and changing channel dimensions. A simple cross-linked microchannel is commonly employed for electrokinetic dispensing. 

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