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.

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.

Joule Heating Induced Temperature Gradient Focusing for Microfluidic Concentration of Samples

2010 ◽  
Author(s):  
Zhengwei Ge ◽  
Chun Yang
Keyword(s):  
Temperature Gradient ◽  
Electric Field ◽  
Joule Heating ◽  
Field Experiments ◽  
Dc Voltage ◽  
Sample Concentration ◽  
Great Achievement ◽  
Temperature Gradient Focusing ◽  
Concentration Enhancement ◽  
High Frequency Ac

Microfluidic concentration of sample species is achieved using the temperature gradient focusing (TGF) in a microchannel with a step change in the cross-section under a pure direct current (DC) field or a combined alternating current (AC) and DC electric field. 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 is introduced in this study. In addition, Joule number effect in the Poly-dimethylsiloxane (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. Results also showed that the high frequency AC electric field which contributes to produce the temperature gradient and reduces the required DC voltage for the sample concentration. The lower DC voltage has generated slower electroosmotic flow (EOF), which reduces the backpressure effect associated with the finite reservoir size. Finally, a more than 2500-fold concentration enhancement was obtained within 14 minutes in the PDMS/PDMS microdevice, which was a great achievement in this TGF technique using inherent Joule heating effects.

Full Field Joule Heating Measurement of Copper Plate Using Phase Shifting Moire´ Interferometry in Microscopic Scale

2009 ◽  
Author(s):  
Bicheng Chen ◽  
Cemal Basaran
Keyword(s):  
Joule Heating ◽  
Current Density ◽  
Moiré Interferometry ◽  
Phase Shifting ◽  
Moire Interferometry ◽  
Heating Effect ◽  
Full Field ◽  
Microscopic Scale ◽  
Joule Heating Effect ◽  
Heating Effects

Heat generated from Joule heating is an important factor in several failure mechanisms in microelectronic packaging (e.g. thermomigration, electromigration and etc) and large amount of the heat causes severe heat dissipation problem. It is further exaggerated by the continuous marching towards miniaturization of microelectronics. The techniques of measuring the Joule heating effects at the microscopic scale are quite limited especially for the full field measurement. Infrared microscopic imaging has been reported to measure the heat radiation by the Joule heating in the microscopic scale. Moire´ interferometry with phase shifting is a highly sensitive and a high resolution method to measure the in-plane full field strain. In this paper, it is demonstrated that the Joule heating effect can be measured by Moire´ interferometry with phase shifting at the microscopic scale. The copper sheet is used for the demonstration because of isotropic material property and well known thermal properties and parameters. The specimen was designed to minimize the out-of-plane strain and the strain caused by the thermal-structural effects. A finite element model was developed to verify the design of the structure of the specimen and the specimen was tested under different current density (input current from 0 to 24 A). Based on the research, a correlation relationship between the current density and the strain in two orthogonal directions (one in the direction of the current flow) was determined. The regression coefficients of the full field were analyzed. The experiment demonstrates the capability of measuring microscopic Joule heating effects by using Moire´ interferometry with phase shifting. The method can be further applied to the measurement of Joule heating effect in the microscopic solid structures in the electronic packaging devices.

Fuzzy Logic Approach for Controlling Temperature in Electroosmotic Flow Fields

2009 ◽  
Author(s):  
Saeid Movahed ◽  
Mohammad Eghtesad ◽  
Reza Kamali
Keyword(s):  
Fuzzy Logic ◽  
Flow Field ◽  
Joule Heating ◽  
Electroosmotic Flow ◽  
Flow Fields ◽  
Heating Effect ◽  
Joule Heating Effect ◽  
Model Based ◽  
Fuzzy Logic Approach ◽  
Flow Field Characteristics

By entering technology to the area of micro and nano scales, the design and fabrication of miniaturized instruments such as microelectronic devices, MEMS, NEMS and ..., become very desirable. Many of these devices deal with flow field in micro- and nano-channels. By decreasing the dimensions of channels, the influence of surface effects becomes prominent and cannot be ignored. One of the most charismatic categories of these phenomena is elecrokinetic effect which can result in electroosmotic flow field (EOF) that has many advantages such as being vibration free, being much more compact, having flat-form velocity and etc. These beneficiaries lead to the increasing stimulus of using this type of flow field. Electroosmosis is defined as the motion of ionized liquid relative to the stationary charged surface by an applied electric field. One of the most important disadvantages of EOF is the Joule heating effect, the generation of heat due to the electroosmosis effect. Besides, micro- and nano-channels are usually used as heat sink in miniaturized devices. By considering these facts, it can be concluded that heat characteristics of EOF must be studied carefully in order to manage and control the Joule heating effect for utilizing the cooling characteristics of micro- and nano-channels. Flow field characteristics can be found by solving Navier-Stocks and Energy equations with proper slip boundary conditions. By considering the partial nature of these equations, many conventional model-based control techniques may not be useful. Therefore, one can suggest some non-model based strategies in order to control the properties of flow fields. In the present study, fuzzy logic controllers will be proposed in order to control the temperature and cooling characteristics of micro- and nano-channel heat sinks.

An all-day solar-driven vapor generator via photothermal and Joule-heating effects

2020 ◽  
Vol 8 (47) ◽  
pp. 25178-25186
Author(s):  
Yang Guo ◽  
Yujin Sui ◽  
Jiajie Zhang ◽  
Zaisheng Cai ◽  
Bi Xu
Keyword(s):  
Joule Heating ◽  
Photothermal Effect ◽  
Heating Effect ◽  
Joule Heating Effect ◽  
Heating Effects ◽  
Vapor Generator

An all-day operating solar evaporator is developed with the photothermal effect in combination with the Joule-heating effect.

3D Numerical Analysis of Joule Heating Effect on Electroosmotic Flow in Microchannels

2006 ◽  
Author(s):  
Reza Monazami ◽  
Shahrzad Yazdi ◽  
Mahmoud A. Salehi
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Charge Distribution ◽  
Cross Section ◽  
Joule Heating ◽  
Electroosmotic Flow ◽  
Three Dimensional ◽  
Micro Channel ◽  
Heating Effect ◽  
Energy Equations

In this paper, a three-dimensional numerical model is developed to analyze the influence of the Joule heating on flow characteristics of an electroosmotic flow through square cross section micro-channels. The governing system of equations consists of three sets of equations: electric potential distribution, flow-field and energy equations. The solution procedure involves three steps. The net charge distribution on the cross section of the micro-channel is computed by solving two-dimensional Poisson-Boltzmann equation using the finite element method. Then, using the computed fluid’s charge distribution, the magnitude of the resulting body force due to interaction of an external electric field with the charged fluid elements is calculated along the micro-channel. Finally, three dimensional coupled Navier-Stokes and energy equations are solved by considering the presence of the electro-kinetic body forces and the volumetric heat generation due to Joule heating for three different external electric field strengths. The results reveal that flow patterns are significantly affected by temperature field distribution caused by Joule heating effect especially for high electric field strength cases.

Numerical Simulation of Joule Heating Effect on Electroosmotic Flow and Electrokinetic Mass Transport in Microchannels

Volume 3 ◽  
2004 ◽  
Author(s):  
Gongyue Tang ◽  
Chun Yang ◽  
Cheekiong Chai ◽  
Haiqing Gong
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Mass Transport ◽  
Joule Heating ◽  
Electroosmotic Flow ◽  
Stokes Equations ◽  
Heating Effect ◽  
Species Transport ◽  
Joule Heating Effect ◽  
Numerical Predictions

This study presents a numerical simulation of Joule heating effect on electroosmotic flow and mass species transport in microchannels, which has direct applications in the capillary electrophoresis based Biochip technology. The proposed model includes the Poisson-Boltzmann equation, the modified Navier-Stokes equations, the conjugate energy equation, and the mass species transport equation. The numerical predictions show that the time development for both the electroosmotic flow field and the Joule heating induced temperature field are less than 1 second. The Joule heating induced temperature field is strongly dependent on channel size, electrolyte concentration, and applied electric field strength. The simulations reveal that the presence of Joule heating can result in significantly different characteristics of the electroosmotic flow and electrokinetic mass transport in microchannels.

Sign in / Sign up

Export Citation Format

Share Document