Dielectrophoresis (DEP) is a promising method for the automated separation of biological cells in a miniaturized format.
This technology allows cells to be manipulated electronically while suspended in a microfluidic channel embedded in a
silicon lab-on-chip. Different dielectrophoretic configurations have been designed and fabricated using micro-electro-mechanical-
systems (MEMS) technology, which are investigated comparatively on their function principles and
separation efficiencies. DEP responses of colloidal polystyrene particles with the diameters of 10.9µm and 21.3µm
suspended in deionized water are measured. It is found that, at the low medium conductivities used, global or local
extreme points of electric fields can be configurated dependent on shapes and geometry sizes of electrodes. In addition,
all the new phenomena appeared during whole experiment are observed, which may provide novel methods to separate
This paper reports the design and experimental analysis of dielectrophoretic traps composed of four microfabricated gold
electrodes excited in a quadrupolar fashion surrounding the electrodes with novel geometries for object detection.
Implemented with a simple single-layer metal process, our microchip device makes the quadrupolar collection electrodes
and detecting electrodes coplanar. Our scheme could not only make the collection system and the detection system in a
chip integrated more easily, but provide possibility to synchronize the two systems and shorten response time. It is found
that, at the low medium conductivities used, the existence of annular or parallel track detecting electrodes can hardly
influence the separation efficiency, which shows that it is possible to drive targets to the object region rapidly by
dielectrophoretic force while all the electrodes within a whole chip are coplanar. Dielectrophoresis effects of colloidal
polystyrene particle are enhanced increasing the frequency of stimulating electric field.