Dissertation
ROTATION OF SPHERICAL MICROPARTICLES IN LINEARLY POLARIZED AC ELECTRIC FIELD
Doctor of Philosophy (PhD), Washington State University
01/2015
Handle:
https://hdl.handle.net/2376/116570
Abstract
With recent advances in low cost lithographic microfabrication techniques, lab-on-a-chip devices find increasing use in various disciplines including biomedical research and analytical chemistry. Electrokinetic manipulation of biological cells in small microfluidic devices is a popular method because of its simplicity and low cost. The purpose of this work is to develop a novel method for dielectric property characterization of microparticles using the combined effects of two electrokinetic phenomena, i.e. Dielectrophoresis and AC electroosmosis. A microfluidic device is fabricated using soft lithography technique on polydimethylsiloxane (PDMS) slab. The microchannels are sealed using a glass slide containing coplanar titanium electrodes. An alternating electric field is established in the device by which suspended microparticles are manipulated. A unique approach has been taken in rotating particles using linearly polarized AC electric field, circumventing the standard requirement of circularly polarized electric field for particle rotation. The medium, particle size, and material are carefully chosen so that particles can be controlled by dielectrophoretic force, while a sufficiently high AC electroosmotic flow is produced for continuous particle rotation. Stable rotation up to 4 rps is observed at 30 Vp-p applied sinusoidal potential in the frequency range of 80 - 1000 Hz.
The particle spin rate observed from the experimental study is then validated with a numerical model. The model is formulated around Laplace equation to determine the electric potential distribution in the domain. Stokes equation is employed to solve for AC electroosmotic fluid flow in the domain. Complexity arising from nonlinear potential drop across the electric double layer (EDL) due to the application of a very large electric potential is also addressed by introducing modified capacitance equation which considers steric effect. This method is useful in determining unknown dielectric property of microparticles / biological cells in a laboratory setting using limited resources and a simple microfluidic device.
Metrics
22 File views/ downloads
12 Record Views
Details
- Title
- ROTATION OF SPHERICAL MICROPARTICLES IN LINEARLY POLARIZED AC ELECTRIC FIELD
- Creators
- Md. Walid Rezanoor
- Contributors
- Prashanta Dutta (Advisor)Robert F. Richards (Committee Member)Robert H. Dillon (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Mechanical and Materials Engineering
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 130
- Identifiers
- 99900581641701842
- Language
- English
- Resource Type
- Dissertation