  Dielectrophoresis is an electric field-based technique for moving neutral
particles through a fluid. When used for particle separation, dielectrophoresis
has many advantages compared to other methods, providing label-free operation
with greater control of the separation forces. In this paper, we design, build,
and test a low-voltage dielectrophoretic device using a 3D printing approach.
This lab-on-a-chip device fits on a microscope glass slide and incorporates
microfluidic channels for particle separation. First, we use multiphysics
simulations to evaluate the separation efficiency of the prospective device and
guide the design process. Second, we fabricate the device in PDMS
(polydimethylsiloxane) by using 3D-printed moulds that contain patterns of the
channels and electrodes. The imprint of the electrodes is then filled with
silver conductive paint, making a 9 pole comb electrode. Lastly, we evaluate
the separation efficiency of our device by introducing a mixture of 3 $\mu$m
and 10 $\mu$m polystyrene particles and tracking their progression. Our device
is able to efficiently separate these particles when the electrodes are
energized with $\pm$12 V at 75 kHz. Overall, our method allows the fabrication
of cheap and effective dielectrophoretic microfluidic devices using commercial
off-the-shelf equipment.
