Current Monitoring Technique

Current monitoring method Current monitoring technique Slope method... 

There have been many methods developed for the zeta potential measurements as mentioned above. Here we will focus on the methods using the current monitoring technique. The zeta potential cannot be directly measured using this method however, it can be determined numerically and analytically through the measured average electroosmotic velocity, which will be summarized below. 

Microfluidic and nanofluidic chips have a wide range of applications in the chemical, biomedical, environmental, and biology areas, where a variety of chemical solutions are used. With the development of microfabrication technology, many new materials such as PDMS and poly (methyl methacrylate) (PMMA) are also employed for chip fabrication. Since each pair of sohd-liquid interface has its unique zeta potential and electroosmotic mobility, which have significant influences on flow control in such small-scale devices, it is very important to experimentally determine these two parameters using the current monitoring technique in order to develop microfluidic and nanofluidic devices for various applications. 

To characterize the electroosmotic mobility of the polybrene surfaces, we performed a series of experiments using the well-established current monitoring technique. In all our experiments, a 25 mM sodium carbonate/bicarbonate run buffer with pH 9.0 was used. Details of the experimental technique can be found in Sze et al. [11]. Briefly, however, to begin, the buffer solution was diluted to 95 % of its original concentration and introduced into a PDMS channel sealed to a glass surface which had undergone the polybrene surface treatment described above. 

Zeta Potential Measurement, Fig. 2 Schematic of the experimental setup for the current-monitoring technique (a)... 

User experience of monitoring techniques in oil and gas production has been reviewed and indicates success and failure for the same methods by different operators. A survey of current monitoring practice in UK offshore fields has been published and other experience related to oil/gas production has be reported . A draft document has been prepared by CEA Task Group E2-5 providing guidelines for monitoring sea-water injection systems. 

It is particularly important to study process phenomena under dynamic (rather than static) conditions. Most current analytical techniques are designed to determine the initial and final states of a material or process. Instmments must be designed for the analysis of materials processing in real time, so that the cmcial chemical reactions in materials synthesis and processing can be monitored as they occur. Recent advances in nuclear magnetic resonance and laser probes indicate valuable lines of development for new techniques and comparable instmmentation for the study of interfaces, complex hquids, microstmctures, and hierarchical assemblies of materials. Instmmentation needs for the study of microstmctured materials are discussed in Chapter 9. 

Five of the criteria are normally considered when any air pollution monitor is designed however, the fifth criterion—portability—is essential in a personal monitor. Obviously, this requirement has an impact on the other criteria because it establishes a challenge for achieving specificity for a chemical or suite of chemicals, for low detection limits for adequate determination of the concentration and exposure, and for units that are not cost-prohibitive. Sensitivity of current personal monitors is less than that for stationary monitoring techniques. Thus, entirely new approaches appear to be necessary for detection of a contaminant in a personal monitor. 

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