Determination of zeta potential by non linear curve fitting method

Fluid motion in most microfluidic systems is often achieved by electroosmotic (EO) flow due to its unique characteristics and advantages. This method allows controlled, high precision handling and pumping of small quantities of fluids through microchannels with the use of electric field. One of the...

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Main Author:	Tan, Mark Aik Chong.
Other Authors:	Lam Yee Cheong
Format:	Final Year Project
Language:	English
Published:	2009
Subjects:	DRNTU::Engineering::Mechanical engineering::Fluid mechanics
Online Access:	http://hdl.handle.net/10356/16210
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Institution:	Nanyang Technological University
Language:	English

id	sg-ntu-dr.10356-16210
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spelling	sg-ntu-dr.10356-162102023-03-04T18:56:54Z Determination of zeta potential by non linear curve fitting method Tan, Mark Aik Chong. Lam Yee Cheong School of Mechanical and Aerospace Engineering DRNTU::Engineering::Mechanical engineering::Fluid mechanics Fluid motion in most microfluidic systems is often achieved by electroosmotic (EO) flow due to its unique characteristics and advantages. This method allows controlled, high precision handling and pumping of small quantities of fluids through microchannels with the use of electric field. One of the characteristic parameter that governs the flow velocity is the Zeta potential. Zeta potential is the electrical potential developed at a surface which is placed in contact with a liquid due to the formation of the electrical double layer. It is difficult to be measured accurately. Current techniques to measure Zeta potential involve experiments that infer the Zeta potential indirectly, with assumptions and approximations that might induce inaccuracies. This work presents a new and more accurate technique to determine Zeta potential by non linear curve fitting method on data obtained through current monitoring experiment. The advantage of this method is the ability to determine both the Zeta potentials of upstream and downstream electrolytes at the same time. In contrast to the conventional current monitoring method, the approximation that the Zeta potentials of both electrolytes are identical is not required. Non linear curve fitting technique also removes errors arising from uncertainties of determining the start and end point of electrolytes displacement in the displacement time method, and also linear curve approximation in the gradient method. A mathematical model with consideration of the mismatch flow fields at the liquid/liquid interface of the upstream and downstream electrolytes during an EO displacement flow of two solutions is adapted from Gan et al (2006) for this investigation. Based on the mathematical model and Ohm’s Law, an equation relating current changes with time is then derived. Curve fitting of the equation on the data obtained from the current monitoring experiments are performed to evaluate the Zeta potentials for the two solutions. A surface conductance term is added to the equation to yield more accurate results. Based on the above development, the Zeta potential values are found to be reasonably close to the results published by other researchers. The results are also found to be approximately similar to values obtained by conventional methods. However, surface conductivity is found to be not reliable due to the limited accuracy of the measuring device. Future work will address the device limitation and surface conductivity can then be evaluated more accurately. Bachelor of Engineering (Mechanical Engineering) 2009-05-22T07:00:30Z 2009-05-22T07:00:30Z 2009 2009 Final Year Project (FYP) http://hdl.handle.net/10356/16210 en Nanyang Technological University 122 p. application/pdf
institution	Nanyang Technological University
building	NTU Library
continent	Asia
country	Singapore Singapore
content_provider	NTU Library
collection	DR-NTU
language	English
topic	DRNTU::Engineering::Mechanical engineering::Fluid mechanics
spellingShingle	DRNTU::Engineering::Mechanical engineering::Fluid mechanics Tan, Mark Aik Chong. Determination of zeta potential by non linear curve fitting method
description	Fluid motion in most microfluidic systems is often achieved by electroosmotic (EO) flow due to its unique characteristics and advantages. This method allows controlled, high precision handling and pumping of small quantities of fluids through microchannels with the use of electric field. One of the characteristic parameter that governs the flow velocity is the Zeta potential. Zeta potential is the electrical potential developed at a surface which is placed in contact with a liquid due to the formation of the electrical double layer. It is difficult to be measured accurately. Current techniques to measure Zeta potential involve experiments that infer the Zeta potential indirectly, with assumptions and approximations that might induce inaccuracies.
author2	Lam Yee Cheong
author_facet	Lam Yee Cheong Tan, Mark Aik Chong.
format	Final Year Project
author	Tan, Mark Aik Chong.
author_sort	Tan, Mark Aik Chong.
title	Determination of zeta potential by non linear curve fitting method
title_short	Determination of zeta potential by non linear curve fitting method
title_full	Determination of zeta potential by non linear curve fitting method
title_fullStr	Determination of zeta potential by non linear curve fitting method
title_full_unstemmed	Determination of zeta potential by non linear curve fitting method
title_sort	determination of zeta potential by non linear curve fitting method
publishDate	2009
url	http://hdl.handle.net/10356/16210
_version_	1759856493359792128

Determination of zeta potential by non linear curve fitting method

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