Abstracts Book - IMRC 2018

• SA5-P023
THE APPLICATION OF MULTILAYERED Co/Ni PERPENDICULAR
MAGNETIC ANISOTROPY (PMA) EFFECT CELL TRAPPING DEVICE
Chris Lynch 2 , Xu Li 2 , Yu-Ching Hsiao 2 , Dino Di Carlo 1 , Reem Khojah 1 , Auni Kundu 2
1 University of California, Los Angeles, Bioengineering, United States. 2 University of California,
Los Angeles, Mechanical and Aerospace Engineering, United States.
Biological cells trapping and manipulation is important in molecular biology
field. Before, cell trapping was a time-consuming and complex process,
especially for a single cell separation. Energy consumption for a massive number
of cell trapping is another issue; for example, electrophoresis sorting cells is
driven by electric field which requires high voltage power supply. To fix this
problem, we designed a patterned superlattice Co/Ni disk array. This structure
with perpendicular magnetic anisotropy (PMA) effect will naturally trap
magnetic-activated cells which, in our case, specifies on the ones carrying
conjugated magnetic beads. As such, this design does not require external
applied force to localize the beads. Moreover, unlike a ring-structured device
capturing beads only at the vortex region, beads can be trapped by magnetic
gradient all around the edge of disk to ensure high-density of trapped beads. In
this work, we deposited multilayered Co/Ni structure on Si substrate and the
structure was patterned into a disk array of radius 4µm and separation distance
12µm between two centers of disk. Thickness (0.2 nm)/(0.5 nm) was chosen for
Co/Ni among the other combinations for its moderate magnetic force due to the
fact Co/Ni has large tunability in saturation magnetization and PMA by relative
thickness,. The saturation magnetization of this combination is 1240 (emu/cc)
obtained SQUID and out-of-plane is shown as easy axis. With the given beads
size (0.4-0.6 µm), we also modeled and simulated to ensure strong enough
captured force for varied sizes of beads. Finally, we flew the beads over the PMA
structure in microfluidic chamber. The fluorescent images showed that a couple
of light points were on top of our fabricated PMA pillars, which proves our PMA
device successfully trap beads and magnetic-activated cells.
Keywords: PMA, microbeads, cell trapping
Presenting authors email: yuching.hsiao@ucla.edu