scholarly journals Joule heating effects on electroosmotic flow in insulator-based dielectrophoresis

2011 ◽  
pp. n/a-n/a ◽  
Author(s):  
Sriram Sridharan ◽  
Junjie Zhu ◽  
Guoqing Hu ◽  
Xiangchun Xuan
Keyword(s):  
Joule Heating ◽  
Electroosmotic Flow ◽  
Heating Effects

Concentration of Samples in Microfluidic Structure Using Joule Heating Effects

2009 ◽  
Author(s):  
Zhengwei Ge ◽  
Chun Yang
Keyword(s):  
Mathematical Model ◽  
Joule Heating ◽  
Electroosmotic Flow ◽  
Scaling Analysis ◽  
Analyte Concentration ◽  
Governing Equations ◽  
Sample Concentration ◽  
Heating Effects ◽  
Concentration Enhancement ◽  
The Mathematical Model

Microfluidic concentration is achieved using temperature gradient focusing (TGF) in a microchannel with a step change in cross-section. A mathematical model is developed to describe the complex TGF processes. The proposed mathematical model includes a set of governing equations for the applied electric potential, electroosmotic flow field, Joule heating induced temperature field, and sample analyte concentration distributions as well. Scaling analysis was conducted to estimate time scales so as to simplify the mathematical model. Numerical computations were performed to obtain the temperature, velocity and sample concentration distributions. Experiments were carried out to study the effects of applied voltage, buffer concentration, and channel size on sample concentration in the TGF processes. These effects were analyzed and summarized using a dimensionless Joule number that was introduced in this study. In addition, Joule number effect in the PDMS/PDMS microdevice was compared with the PDMS/Glass microdevice. A more than 450-fold concentration enhancement was obtained within 75 seconds in the PDMS/PDMS microdevice. Overall, the numerical simulations were found in a reasonable agreement with the experimental results.

Towards High Concentration Enhancement of Microfluidic Temperature Gradient Focusing of Sample Solutes

2011 ◽  
Author(s):  
Zhengwei Ge ◽  
Chun Yang
Keyword(s):  
Temperature Gradient ◽  
Electric Field ◽  
Joule Heating ◽  
Electroosmotic Flow ◽  
High Concentration ◽  
Temperature Gradient Focusing ◽  
Heating Effects ◽  
Concentration Enhancement ◽  
Dc Electric Field ◽  
High Frequency Ac

This paper reports an improved technique to enhance microfluidic temperature gradient focusing (TGF) of sample solutes using Joule heating effects induced by a combined AC and DC electric field. By introducing the AC field component, additional Joule heating effects are obtained to generate temperature gradient for concentrating sample solutes, while the electroosmotic flow is suppressed under the high frequency AC electric field. Therefore, the required DC voltages for achieving certain sample concentration by Joule heating induced TGF technique are remarkably reduced. Moreover, the lower DC voltages lead to smaller electroosmotic flow (EOF), thereby reducing the backpressure effects due to the finite reservoir size. Concentration enhancements of sample solutes are improved by using a combined AC and DC electric field.

Microfluidics Concentration of Sample Solutes Using Joule Heating Effects Under Combined AC and DC Electric Field

2010 ◽  
Author(s):  
Zhengwei Ge ◽  
Chun Yang
Keyword(s):  
Temperature Gradient ◽  
Electric Field ◽  
Joule Heating ◽  
Electroosmotic Flow ◽  
Heating Effect ◽  
Dc Voltage ◽  
Joule Heating Effect ◽  
Heating Effects ◽  
Concentration Enhancement ◽  
Dc Electric Field

Microfluidic concentration is achieved by utilizing Joule heating effect induced temperature gradient focusing (TGF) under a combined AC and DC electric field imposed in a straight microchannel with sudden expansion in cross-section. The introduction of AC electric field component services dual functions: one is to produce Joule heating effects for generating temperature gradient, and the other is to suppress electroosmotic flow with high frequencies. Therefore, the required DC voltage for achieving sample concentration with Joule heating induced TGF technique is remarkably reduced. The lower DC voltage can lead to smaller electroosmotic flow (EOF), thereby reducing the backpressure effect due to the finite reservoir size. It was demonstrated that using the proposed new TGF technique with Joule heating effect under a combined AC and DC field, more than 2500-fold concentration enhancement was obtained within 14 minutes in a PDMS/PDMS microdevice, which is an order of magnitude higher than the literature reported concentration enhancement achieved by microfluidic devices utilizing the Joule heating induced TGF technique.

Modeling and Visualizing Electroosmotic Microchannel Flow With Joule Heating Effects

2004 ◽  
Author(s):  
Xiangchun Xuan ◽  
David Sinton ◽  
Bo Xu ◽  
Dongqing Li
Keyword(s):  
Joule Heating ◽  
Electroosmotic Flow ◽  
Velocity Profiles ◽  
Microchannel Flow ◽  
Liquid Temperature ◽  
Temperature Distributions ◽  
Heating Effects ◽  
Temperature Plateau ◽  
Measured Liquid ◽  
Electroosmotic Velocity

Electroosmotic flow with Joule heating effects was examined numerically and experimentally in a micro capillary. Fluorescence-based thermometry and velocimetry techniques were employed to visualize the liquid temperature and the electroosmotic velocity profile, respectively. Sharp temperature drops close to the two ends and a high-temperature plateau in the middle of the capillary were observed. Correspondingly, concave-convex-concave velocity profiles were observed in the inlet-middle-outlet regions of the homogeneous capillary. The measured liquid temperature distributions and electroosmotic velocity profiles along the capillary agree well with the predictions of a theoretical model developed in this paper.

scholarly journals Joule Heating Effects on Transport-Induced-Charge Phenomena in an Ultrathin Nanopore

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1041
Author(s):  
Zhixuan Wang ◽  
Wei-Lun Hsu ◽  
Shuntaro Tsuchiya ◽  
Soumyadeep Paul ◽  
Amer Alizadeh ◽  
...  
Keyword(s):  
Joule Heating ◽  
Electroosmotic Flow ◽  
Chemical Potential ◽  
Local Maximum ◽  
Dynamics Simulation ◽  
Fluid Behavior ◽  
Heating Effects ◽  
Complex Fluid ◽  
Induced Charge ◽  
Chemical Potential Gradients

Transport-induced-charge (TIC) phenomena, in which the concentration imbalance between cations and anions occurs when more than two chemical potential gradients coexist within an ultrathin dimension, entail numerous nanofluidic systems. Evidence has indicated that the presence of TIC produces a nonlinear response of electroosmotic flow to the applied voltage, resulting in complex fluid behavior. In this study, we theoretically investigate thermal effects due to Joule heating on TIC phenomena in an ultrathin nanopore by computational fluid dynamics simulation. Our modeling results show that the rise of local temperature inside the nanopore significantly enhances TIC effects and thus has a significant influence on electroosmotic behavior. A local maximum of the solution conductivity occurs near the entrance of the nanopore at the high salt concentration end, resulting in a reversal of TIC across the nanopore. The Joule heating effects increase the reversal of TIC with the synergy of the negatively charged nanopore, and they also enhance the electroosmotic flow regardless of whether the nanopore is charged. These theoretical observations will improve our knowledge of nonclassical electrokinetic phenomena for flow control in nanopore systems.

Electroosmotic flow with Joule heating effects

Lab on a Chip ◽  
2004 ◽  
Vol 4 (3) ◽  
pp. 230 ◽  
Author(s):  
Xiangchun Xuan ◽  
Bo Xu ◽  
David Sinton ◽  
Dongqing Li
Keyword(s):  
Joule Heating ◽  
Electroosmotic Flow ◽  
Heating Effects
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