PhD Defense, Chris Earhart (July 28, Wednesday, 2010, CISX Auditorium 9:30 am)

Chris Earhart cearhart at
Wed Jul 21 14:35:54 PDT 2010

A Ph.D. Defense Announcement

"Magnetic Sifter and Nanoparticles for Cell and Protein Separation"

PhD Candidate: Chris Earhart

Department of Materials Science and Engineering

Advisor: Professor Shan X. Wang

Date: Wednesday, July 28, 2010
Time: 9:30 am (refreshments at 9:15 am)
Place: CIS-X Auditorium (Rm 101)


Nanoscience and nanotechnology have been applied in recent years to cancer
research, with the goal of making a revolutionary change in the ways in
which cancer is diagnosed and treated.  Magnetic nanotechnologies, in
particular, have shown significant potential in several areas such as
imaging, therapeutics, and early detection.  The topic of this presentation
is a novel magnetic separation device, the magnetic sifter, and physically
fabricated magnetic nanoparticles for applications in cell and protein

The magnetic sifter is a microfabricated planar die containing a dense array
of pores (~200-5000/mm2) in a magnetically soft membrane.  When magnetized
by an external field, the sifter pores generate large magnetic field
gradients near the pore edges, which capture nanoscale magnetic carriers
during flow with high efficiency and throughput.  The magnetic sifter is a
microfluidic device, in the sense that it contains microfabricated,
micron-scale pores for fluid flow.  It is also a macrofluidic device, in
that high-volume throughput is achieved by parallel flow through the large
number of pores.

When paired with magnetic carriers functionalized with recognition moieties,
the magnetic sifter can be used in both cell and protein enrichment
schemes.  Separations of magnetically labeled tumor cells and individual
magnetic nanoparticles using the sifter will be discussed.  With its planar
structure and presentation of captured cells, the sifter can also be used as
a cell imaging platform.  The use of the sifter to capture and quantify low
concentrations (~100/mL) of tumor cells in whole blood samples has been

Lastly, a method for high-throughput fabrication of novel magnetic carriers,
synthetic antiferromagnetic (SAF) nanoparticles, will be presented.  The
method has enabled production of large quantities of SAF nanoparticles,
which have desirable properties for applications in magnetic separation.
The capture and release of SAF nanoparticles with the magnetic sifter has
been shown.  High capture efficiencies are achieved at flow rates 10-20x
higher than what was previously possible with commercially available
magnetic carriers.
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