Joule heating effects and the experimental determination of temperature during CE

Evenhuis, Christopher J.; Haddad, Paul R.

doi:10.1002/elps.200800643

Cited by 53 publications

(58 citation statements)

References 70 publications

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“…It has been long known in capillary electrophoresis that Joule heating can elevate the buffer temperature and disturb the electroosmotic flow causing significant sample dispersion [30][31][32][33]. The effects of Joule heating on fluid temperature and motion in eDEP have been investigated previously [34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

et al. 2011

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Joule heating effects on electroosmotic flow in insulator-based dielectrophoresisInsulator-based dielectrophoresis (iDEP) is an emerging technology that has been successfully used to manipulate a variety of particles in microfluidic devices. However, due to the locally amplified electric field around the in-channel insulator, Joule heating often becomes an unavoidable issue that may disturb the electroosmotic flow and affect the particle motion. This work presents the first experimental study of Joule heating effects on electroosmotic flow in a typical iDEP device, e.g. a constriction microchannel, under DC-biased AC voltages. A numerical model is also developed to simulate the observed flow pattern by solving the coupled electric, energy, and fluid equations in a simplified two-dimensional geometry. It is observed that depending on the magnitude of the DC voltage, a pair of counter-rotating fluid circulations can occur at either the downstream end alone or each end of the channel constriction. Moreover, the pair at the downstream end appears larger in size than that at the upstream end due to DC electroosmotic flow. These fluid circulations, which are reasonably simulated by the numerical model, form as a result of the action of the electric field on Joule heatinginduced fluid inhomogeneities in the constriction region.

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Section: Introductionmentioning

confidence: 99%

Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

et al. 2011

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“…In contrast, if the ratio of surface area to the volume of the channel of the chip-based CE is higher, joule heating is released easily, and higher field can be used to achieve improved resolution, which in turn leads to an excellent separation of homoduplexes and heteroduplexes in TGCE. 42,43 Second, according to the separation principle of TGCE, the resolution efficiency for mutant DNA fragments is dependent on the temperature melting profile of the detected sequences. If the mutant sequence is located in the lowmelting domain in a whole DNA fragment, the migration differences between heteroduplexes and homoduplexes during CE are readily produced and retained.…”

Section: Discussionmentioning

confidence: 99%

Rapid detection of low-abundance K-ras mutation in stools of colorectal cancer patients using chip-based temperature gradient capillary electrophoresis

Zhang

Wang

et al. 2011

Laboratory Investigation

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Mutant K-ras provides an independent negative predictive marker for epidermal growth factor receptor (EGFR)-targeted therapy in colorectal cancers (CRCs). Rapid, sensitive, and cost-effective screening for K-ras status will overarch rational personalized medicine. Stool-based DNA testing offers unique advantages for CRC screening such as noninvasiveness, high specificity, and patient compliance, whereas complicated procedures and the low sensitivity of the present approaches have hampered its application on a wide scale. In this study, a chip-based temperature gradient capillary electrophoresis (TGCE) technique was applied to detect low-abundance K-ras mutations under a pooled experiment and analyze K-ras mutations in 30 paired stool samples and cancer tissues of CRC patients and 15 stool samples of healthy volunteers. The chip-based TGCE results showed that the successful analysis of K-ras status could be achieved within 6 min with an extremely low sample consumption of 14 nl. Detection is sensitive enough to reliably report 0.2% mutant CRC cells in a wild-type background, and 0.5 ng of template DNA was sufficient for chip-based TGCE. Of the 30 stool samples of CRC patients analyzed, 17 (57%) harbored K-ras mutations, and the lowest percentage of the detectable mutant K-ras in stool samples was 2%. The coincidence rate for K-ras mutations between stools and tissues obtained by the chip-based method reached 97% (29/30). One of the 15 stool samples of normal controls carried K-ras mutations, producing a specificity of 93%. Clone sequencing data entirely confirmed the results obtained by chip-based TGCE. The study demonstrates that chip-based TGCE is capable of rapidly screening low-abundance K-ras mutations with high sensitivity, reproducibility, simplicity, and significant savings of time and sample. Application of this method to genotype the K-ras gene in stools would provide a potential means for predicting the effectiveness of EGFR-targeted therapy in CRC patients using noninvasive approaches.

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“…This allows the fluid to be pumped through the microchannel by means of an electric field. However, for the studies done in this thesis, Joule heating is considered to act to the detriment of the system, which is typical for most experiments [72]. The Joule heating power is expressed by [72] …”

Section: Electrohydrodynamic Forcesmentioning

confidence: 99%

“…Many researchers have noted the existence of a positive feedback loop between conductance and temperature [72]. This relationship can be expressed by…”

Section: Electrohydrodynamic Forcesmentioning

confidence: 99%

“…where σ m,mean and σ m,298 are the average conductivity and the conductivity at 298 K, respectively, T mean is the average temperature, and γ 1 and γ 2 are temperature coefficients with units of K -1 and K -2 , respectively [72]. This relationship indicates that as temperature increases, so does the conductance of the fluid.…”

Section: Electrohydrodynamic Forcesmentioning

confidence: 99%

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Trapping of nanoparticles with dielectrophoretic nano-probes.

Wood¹

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negative dielectrophoresis repels particles from the region of the highest electric field gradient. The dielectrophoretic force is directly proportional to the square of the electric field gradient, as well as the cube of the radius of the particles involved.As particles decrease in size, the gradient of the electric field must increase rapidly in order to capture or repel the particles. The intense electric field gradients were produced using fabricated silver gallium (Ag 2 Ga) nano-probes electrodes in conjunction with indium tin oxide (ITO) coated microscope cover slips, which served as the opposite electrode. The silver gallium nano-probes ranged from approximately 100-500 nm in diameter and were typically positioned less than 40 µm above the ITO cover slips.Positive and negative dielectrophoretic forces were able to dominate the other electrokinetic forces acting on sub-micron particles, which were suspended in deionized water and aqueous potassium chloride, using the nano-probes and ITO cover slips as electrodes. Colloidal quantum dots of gold, as small as 5 nm in diameter, were captured using positive DEP forces, as were sub-micron fluorescent polystyrene particles.Negative DEP forces repelled sub-micron fluorescent polystyrene particles suspended in a low conductivity solution.

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Joule heating effects and the experimental determination of temperature during CE

Cited by 53 publications

References 70 publications

Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

Rapid detection of low-abundance K-ras mutation in stools of colorectal cancer patients using chip-based temperature gradient capillary electrophoresis

Trapping of nanoparticles with dielectrophoretic nano-probes.

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