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Dielectrophoretic Cell Trapping for Media Exchange on a Microfluidic Algal Cultivator
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Date
2014Type
ThesisDepartment
Mechanical Engineering
Degree Level
Master's Degree
Abstract
Through COMSOL modeling and electrode design, positive dielectrophoretic (pDEP) cell trapping
for media exchange has been demonstrated on live Chlamydomnas reinhardtii (C. reinhardtii)microalgae
cells in regular growth medium in a PDMS-glass microfluidic MEMS device. Dielectrophoresis (DEP) is the
force applied to dielectric particles in a non-uniform alternating current (AC) electric field. A DEP force
toward the increasing electric field gradient is called positive. In literature pDEP trapping over large
areas has been demonstrated with the use of low conductivity suspending media, while for higher
conductivity suspending media, such as growth media, the pDEP force is reduced, and less likely to trap
and hold microalgae against the hydrodynamic forces during media exchange. Media exchange allows
for the removal of cellular waste and replenishment of nutrients. Multiphysics software, COMSOL, was
used to model repeating structures suited for trapping of cells over an area of a microfluidic device. For
single shell model, dielectrophoretic force on a homogenous sphere in a homogenous medium in an
electric field is a function of the sphere radius, particle conductivity and permittivity, medium
conductivity and permittivity, and the gradient of the electric field. By assuming the conductivities,
permittivities, and the particle geometry remains constant, the gradient of the electric field is the
determining factor for the strength of the pDEP force. Modeling the electric fields and the resulting
electric field gradient of various interdigitated electrode configurations allowed for the optimization of
an electrode structure’s area of higher electric field gradients. The completed microfluidic device
consisted of a single channel and a wide growth chamber overlaid over patterned gold-chrome
electrodes fabricated using soft lithography and photolithography. The pDEP trapping was successful in
trapping C. reinhardtii for media exchange.
Permanent link
http://hdl.handle.net/11714/2994Additional Information
Committee Member | Hiibel, Sage R; Zhu, Xiaoshan |
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Rights | In Copyright(All Rights Reserved) |
Rights Holder | Author(s) |