Continuous On-Chip Cell Separation Based on Conductivity-Induced Dielectrophoresis with 3D Self-Assembled Ionic Liquid Electrodes

Dielectrophoresis (DEP) has been
widely explored to separate cells
for various applications. However, existing DEP devices are limited
by the high cost associated with the use of noble metal electrodes,
the need of high-voltage electric field, and/or discontinuous separation
(particularly for devices without metal electrodes). We developed
a DEP device with liquid electrodes, which can be used to continuously
separate different types of cells or particles based on positive DEP.
The device is made of polydimethylsiloxane (PDMS), and ionic liquid
is used to form the liquid electrodes, which has the advantages of
low cost and easy fabrication. Moreover, the conductivity gradient
is utilized to achieve the DEP-based on-chip cell separation. The
device was used to separate polystyrene microbeads and PC-3 human
prostate cancer cells with 94.7 and 1.2% of the cells and microbeads
being deflected, respectively. This device is also capable of separating
live and dead PC-3 cancer cells with 89.8 and 13.2% of the live and
dead cells being deflected, respectively. Moreover, MDA-MB-231 human
breast cancer cells could be separated from human adipose-derived
stem cells (ADSCs) using this device with high purity (81.8 and 82.5%
for the ADSCs and MDA-MB-231 cells, respectively). Our data suggest
the great potential of cell separation based on conductivity-induced
DEP using affordable microfluidic devices with easy operation.