Current-monitoring method for measuring the electroosmotic flow rate in capillary zone electrophoresis

Huang, Xiaoxia; Gordon, Manuel J.; Zare, Richard N.

doi:10.1021/ac00168a040

Cited by 521 publications

(462 citation statements)

References 7 publications

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“…The determined electroosmotic mobilities in silicon dioxide micro-and nanofluidic channel system are in the range of the electroosmotic mobilities of fused silica capillaries (5 · 10 À4 cm 2 /V s) and borosilicate glass capillaries (1.5 · 10 À3 cm 2 /V s) under similar conditions (Huang et al 1988;Gaudioso et al 2002).…”

Section: Resultsmentioning

confidence: 61%

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Fabrication and electroosmotic flow measurements in micro- and nanofluidic channels

Hug

Rooij

Staufer

2005

Microfluid Nanofluid

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Section: Resultsmentioning

confidence: 61%

“…2e. Electroosmotic flow measurements were based on current measurements according to the method of Huang et al 1988. The conductivity measurements were performed with a Labview-controlled Keithley-236-Source-Measure-Unit.…”

Section: Electroosmotic Flow (Eof) Measurementsmentioning

confidence: 99%

Fabrication and electroosmotic flow measurements in micro- and nanofluidic channels

Hug

Rooij

Staufer

2005

Microfluid Nanofluid

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“…With the present detection method, chip electroosmotic mobility can be measured by monitoring the signal change associated to a step change of running buffer of different conductivity [29]. Before the interface between the two buffers reaches the detection cell, the cell contains only the original buffer and the solution resistance is therefore uniform.…”

Section: Electroosmotic Mobility Measurementmentioning

confidence: 99%

On‐column conductivity detection in capillary‐chip electrophoresis

Fang

Josserand

2007

Electrophoresis

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On-column conductivity detection in capillary-chip electrophoresis was achieved by actively coupling the high electric field with two sensing electrodes connected to the main capillary channel through two side detection channels. The principle of this concept was demonstrated by using a glass chip with a separation channel incorporating two double-Ts. One double-T was used for sample introduction, and the other for detection. The two electrophoresis electrodes apply the high voltage and provide the current, and the two sensing electrodes connected to the separation channel through the second double-T and probe a potential difference. This potential difference is directly related to the local resistance or the conductivity of the solution defined by the two side channels on the main separation channel. A detection limit of 15 mM (600 ppb or 900 fg) was achieved for potassium ion in a 2 mM Tris-HCl buffer (pH 8.7) with a linear range of 2 orders of magnitude without any stacking. The proposed detection method avoids integrating the sensing electrodes directly within the separation channel and prevents any direct contact of the electrodes with the sample. The baseline signal can also be used for online monitoring of the electric field strength and electroosmosis mobility characterization in the separation channel.

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“…14,15 Because of its instrumental simplicity, the currentmonitoring method is also very popular. [16][17][18][19][20][21] In this method, the microchannel is filled with an electrolyte (for example, 10 mmol L -1 phosphate buffer) and the solution in one of the reservoirs is replaced by a more diluted electrolyte (for example, 9.0 mmol L -1 phosphate buffer). The high voltage is applied and the resulting current is monitored.…”

Section: Introductionmentioning

confidence: 99%

Visible LED-Based Instrumentation for Photometric Determination of Electroosmotic Flow in Microchannels

Silva¹,

Deblire²,

Jesus³

et al. 2011

J. Braz. Chem. Soc.

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A instrumentação para a determinação fotométrica do fluxo eletrosmótico (EOF) em dispositivos microfluídicos é descrita neste trabalho. A instrumentação é baseada em componentes acessíveis e consiste em um microscópio trinocular e no fotodiodo integrado OPT101. Um diodo emissor de luz (LED) de alta intensidade foi utilizado como fonte de radiação. Para as determinações foram utilizadas soluções aquosas dos corantes azul patente V e azul de metileno. O sistema foi utilizado no monitoramento do EOF em microdispositivos de poli(dimetilsiloxano) (PDMS) e híbridos de toner/vidro. As mobilidades do EOF determinadas em pH 7,0 foram (5,75 ± 0,01)10 -4 cm 2 V -1 s -1 e (3,2 ± 0,1)10 -4 cm 2 V -1 s -1 para os dispositivos de toner/vidro e PDMS, respectivamente. Medidas reprodutíveis foram obtidas em todos os experimentos, levando a uma alta precisão na determinação. O método proposto foi comparado com o método tradicional de determinação do EOF que envolve a medida da corrente nos microcanais.An instrumental setup for electroosmotic flow (EOF) determination in microfluidic devices is described. The system is based on a trinocular microscope and an integrated photodiode OPT101. The radiation was provided by a high-intensity white LED. For the determinations, patent blue V and methylene blue aqueous solutions were used. The setup was applied for EOF monitoring in hybrid toner/glass and PDMS microchips. For the toner/glass device, the EOF mobility was determined to be (5.75 ± 0.01) 10 -4 cm 2 V -1 s -1 at pH 7.0. For PDMS devices the measured EOF mobility was (3.2 ± 0.1) 10 -4 cm 2 V -1 s -1 . Reproducible measurements were obtained in all experiments, which produced results with small errors. The proposed method was compared to the conventional current monitoring method.Keywords: electroosmotic flow, mTAS, Lab-on-a-chip, photometric methods, microfluidic devices IntroductionElectroosmotic flow (EOF) is the movement of solvent molecules caused by an applied voltage in a capillary system. EOF plays an essential role in electromigration separation techniques, such as capillary zone electrophoresis (CZE or free solution capillary electrophoresis, FSCE) or microchip electrophoresis, 1 since the velocity of the ions is influenced by the magnitude of the EOF. As an example, both positively and negatively charged species can be simultaneously analyzed due to the EOF. Moreover, the EOF magnitude could bring some information about the condition of the surface of the capillary or microchannel wall. In particular, the knowledge about the surface charge density (including not only the EOF magnitude but also the zeta potential) can be of paramount importance for preventing adsorption of analyte to the wall.It is well accepted that EOF has its origin on the unbalanced charge distribution in the region closer to the capillary/microchannel wall, the so called electrical double layer (EDL). More precisely, the flow is caused by the movement of excess ions in the diffuse portion of the EDL. Mathematical treatment of the EOF combines the Newto...

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Current-monitoring method for measuring the electroosmotic flow rate in capillary zone electrophoresis

Cited by 521 publications

References 7 publications

Fabrication and electroosmotic flow measurements in micro- and nanofluidic channels

Fabrication and electroosmotic flow measurements in micro- and nanofluidic channels

On‐column conductivity detection in capillary‐chip electrophoresis

Visible LED-Based Instrumentation for Photometric Determination of Electroosmotic Flow in Microchannels

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