Current Monitoring Method

Huang, X.H., Gordon, M.J., and Zare, R.N., Current-monitoring method for measuring the electroosmotic flow-rate in capillary zone electrophoresis. Ana/. Chem., 1988, 60 1837-1838. 

Current monitoring method Current monitoring technique Slope method... 

There are three commonly used methods to measure the zeta potential, which involves pressure-driven flow, electrophoresis, and electroosmotic-driven flow, respectively. For the measurement of the specific surface conductivity, there are primarily two methods involving pressure-driven flow and electroosmotic-driven flow. In this entry, we will focus on the electrical current monitoring methods which can be used to measure the zeta potential, specific surface conductivity, volumetric flow rate, and electroosmotic mobility by employing electroosmotic flow with a solution displacement process. 

Electrical Current Monitoring Methods, Fig. 1 A typical current-time relationship measured for a 1 x TAE buffer solution replacing a 95 % 1 x TAE buffer solution in a 10 cm length of 100 pm i.d. capillary, under an applied electrical field of 7.5 kV/m... 

In the electrical current monitoring methods, a microchannel filled with mie electrolyte solution is brought into contact with two reservoirs, one of which has the same concentration as that in the microchannel and the other has a higher concentration. The electrical field is set up simultaneously so that the more concentrated mie will gradually replace the less concentrated one in the... 

Electrical Current Monitoring Methods, Fig. 3 Illustration of the velocity vaiiatirai in a parallel plate microchannel... 

Electroosmotic flow has been used as a major pumping mechanism for microfluidic devices. The current monitoring methods, which use electroosmotic flow as a transport mechanism for solution replacement processes, have been used... 

In the hterature, several methods such as the neutral marker method, the current monitoring method [5], etc. have been introduced to indirectly determine the average liquid velocity of the EOF in a tnicrocapillary so that the capillary -potential can be determined using Eq. 3. However, in practice, there exist difficulties in identifying a real, electrically neutral marker and in locating the cutoff of the asymptotic current vs. time curve. 

Bubble Dynamics in Microchannels Electrical Current Monitoring Methods... 

The suggested experimental setup (Fig. 2) and procedure used for zeta potential measurements is identical to that used for the time-interval current-monitoring method of Huang et al. [9]. The procedure used for measuring can be described briefly as follows. 

Temperature Effects on the Zeta Potential, Fig. 3 Schematic diagram of the current-monitoring method used to measure zeta potential (Q. As time increases, a higher-concentration buffer displaces a lower-concentration version of the same buffer solution. 

Fig. 6 Plot of the electroosmotic velocity as a function of the applied electric field for two buffers (a) 1 x TAE and (b) 1 X TBE. Results for both the direct fiow visualization method and the current-monitoring method are shown [6]...

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