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Microscale electrokinetic transport ...

Chen, Chuan-Hua.

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Microscale electrokinetic transport and stability.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Microscale electrokinetic transport and stability./
Author:	Chen, Chuan-Hua.
Description:	130 p.
Notes:	Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 2053.
Contained By:	Dissertation Abstracts International65-04B.
Subject:	Engineering, Mechanical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3128628
ISBN:	0496758905

Microscale electrokinetic transport and stability.
Chen, Chuan-Hua.

Microscale electrokinetic transport and stability. - 130 p.

Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 2053.

Thesis (Ph.D.)--Stanford University, 2004.

Electrokinetics is a leading mechanism for transport and separation of biochemical samples in microdevices due to its favorable scaling at small scales. However, electrokinetic systems can become highly unstable, and this instability adversely affects key processes such as sample stacking and electrophoretic separation. This dissertation deals with two major topics: a novel planar micropump exploiting the favorable scaling of electroosmosis at the microscale, and a fundamental study of electrokinetic flow instabilities induced by electrical conductivity gradients.

ISBN: 0496758905Subjects--Topical Terms:

783786
Engineering, Mechanical.

Microscale electrokinetic transport and stability.
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040 $a UnM $c UnM
100 1 $a Chen, Chuan-Hua. $3 1928110
245 1 0 $a Microscale electrokinetic transport and stability.
300 $a 130 p.
500 $a Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 2053.
500 $a Adviser: Juan G. Santiago.
502 $a Thesis (Ph.D.)--Stanford University, 2004.
520 $a Electrokinetics is a leading mechanism for transport and separation of biochemical samples in microdevices due to its favorable scaling at small scales. However, electrokinetic systems can become highly unstable, and this instability adversely affects key processes such as sample stacking and electrophoretic separation. This dissertation deals with two major topics: a novel planar micropump exploiting the favorable scaling of electroosmosis at the microscale, and a fundamental study of electrokinetic flow instabilities induced by electrical conductivity gradients.
520 $a Electroosmotic micropumps use field-induced ion drag to drive liquids and achieve high pressures in a compact design with no moving parts. An analytical model applicable to planar, etched-structure micropumps was developed to guide the geometrical design and working fluid selection. Standard microlithography and wet etching techniques were used to fabricate a pump 1 mm long along the flow direction and 0.9 mum by 38 mm in cross section. The pump produced a maximum pressure of 0.33 atm and a maximum flow rate of 15 mul/min at 1 kV applied potential with deionized water as working fluid. The pump performance agreed well with the theoretical model.
520 $a Electrokinetic flow instabilities occur under high electric field in the presence of electrical conductivity gradients. In a microfluidic T-junction 11 mum by 155 mum in cross section, aqueous electrolytes of 10:1 conductivity ratio were electrokinetically driven into a common mixing channel. Convectively unstable waves were observed at 0.5 kV/cm, and upstream propagating waves at 1.5 kV/cm. A physical model for this instability has been developed. A linear stability analysis of the governing equations in the thin-layer limit predicts both qualitative trends and quantitative features that agree well with experimental data. Briggs-Bers criteria were applied to select physically unstable modes and determine the nature of instability. Conductivity gradients and bulk charge accumulation are a crucial factor in the instability. The role of electroosmotic flow is mainly as a convecting medium. The instability is governed by two key controlling parameters: the ratio of dynamic to dissipative forces which determines the onset of instability, and the ratio of electroviscous to electroosmotic velocities which governs the convective versus absolute nature of instability.
590 $a School code: 0212.
650 4 $a Engineering, Mechanical. $3 783786
650 4 $a Engineering, Chemical. $3 1018531
650 4 $a Physics, Fluid and Plasma. $3 1018402
650 4 $a Engineering, Biomedical. $3 1017684
690 $a 0548
690 $a 0542
690 $a 0759
690 $a 0541
710 2 0 $a Stanford University. $3 754827
773 0 $t Dissertation Abstracts International $g 65-04B.
790 1 0 $a Santiago, Juan G., $e advisor
790 $a 0212
791 $a Ph.D.
792 $a 2004
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3128628