Electroosmotic Instability

Zholkovsky et al. [4] analyzed the stability of CP at a perfectly charge selective interface under conditions of equilibrium electroosmosis. They showed that equilibrium electroosmotic instability is unfeasible for a low-molecular aqueous electrolyte. 

Extended Space Charge in Concentration Polarization, Nonequilibrium Electroosmotic Slip, and Electroosmotic Instability... 

Electroosmotic Instability, Fig. 4 Dependence of elec- dashed line), (b) - Uj versus C continuous line),... 

Electric fields may interact with flows fed by hydrostatic or pumping action [91]. Flows driven by electroosmotic means may be mixed as well by the action of fluctuating electric fields, which creates oscillating electroosmotic flows and has been termed electrokinetic instability (EKI) [25, 93], In this way, rapid stretching and folding of material lines are induced, not unlike the effect of stirring. In one realized example, comparatively low frequencies, below -100 Hz, and electric field strengths in excess of 100 V mm1 are applied for channels with dimensions of about 50 pm [25],... 

Mixer 3 [M 3] Electrokinetic Instability Electroosmotic Flow Micro Mixer, First-generation Device... 

Electrokinetic instability electroosmotic flow mixer, lst-generation device... 

E E(t) EDM EDTA EDX EHD EKI EO EOF ESI-MS Ez Activation energy Exit-age distribution function Electro-discharge machining Ethylene-diamine-tetraacetic acid Energy dispersive X-ray Electrohydrodynamic Electrokinetic instability Electroosmotic-Electroosmotic flow Electrospray ionization mass spectrometry Electric field... 

Physically, the hysteresis roots in that fact that the effect of the electric force on the stability of 1D conduction is different in different parts of the diffusion layer. Indeed, this force stabilizes ID conduction in the electroneutral bulk and in the quasi-equUibrium portion of EDL and destabilizes it in the ESC region. The nonlinear flow resulting from this instability reduces concentration polarization and, thus, weakens the hampering effect of the electric force in the bulk in the down way portion of the hysteresis loop. In order to verify this mechanism, a model electroosmotic formulation without electric force term in the Stokes equation was analyzed. As illustrated in Fig. 8, this modification results in shrinking of the hysteresis loop. The bifurcation still remains subcritical and the hysteresis loop still exists owing to the hampering effect of the electric force in the quasi-equilibrium portion of the EDL, implicit in the first term in the electroosmotic slip conditions (21). 

The disadvantages of CE compared to IC include lower sensitivity, higher concentration detection limits, and somewhat poorer reproducibility of qualitative and quantitative data owing to instability of the electroosmotic flow (EOF). IC has so far been developed more extensively. Validated procedures and computer optimization approaches are available... 

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