Development of a 3D Graphene Electrode Dielectrophoretic Device

Abstract

The design and fabrication of a novel 3D electrode microdevice using 50 µm thick graphene paper and 100 µm double sided tape is described. The protocol details the procedures to construct a versatile, reusable, multiple layer, laminated dielectrophoresis chamber. Specifically, six layers of 50 µm x 0.7 cm x 2 cm graphene paper and five layers of double sided tape were alternately stacked together, then clamped to a glass slide. Then a 700 μm diameter micro-well was drilled through the laminated structure using a computer-controlled micro drilling machine. Insulating properties of the tape layer between adjacent graphene layers were assured by resistance tests. Silver conductive epoxy connected alternate layers of graphene paper and formed stable connections between the graphene paper and external copper wire electrodes. The finished device was then clamped and sealed to a glass slide. The electric field gradient was modeled within the multi-layer device. Dielectrophoretic behaviors of 6 μm polystyrene beads were demonstrated in the 1 mm deep micro-well, with medium conductivities ranging from 0.0001 S/m to 1.3 S/m, and applied signal frequencies from 100 Hz to 10 MHz. Negative dielectrophoretic responses were observed in three dimensions over most of the conductivity-frequency space and cross-over frequency values are consistent with previously reported literature values. The device did not prevent AC electroosmosis and electrothermal flows, which occurred in the low and high frequency regions, respectively. The graphene paper utilized in this device is versatile and could subsequently function as a biosensor after dielectrophoretic characterizations are complete. Video LinkThe video component of this article can be found at

Microfluidic Platform for Cell Isolation and Manipulation Based on Cell Properties

“…The target cells may be subsequently released into a separate collection reservoir by removing the voltage applied to the microwells. The design is similar to microliter well plates but scaled down in size and fabricated by drilling holes in a three-dimensional laminate made from stacked layers of graphene [ 155 ] or copper [ 156 ] sheet (interleaved with insulating layers). The resulting microwell walls act as electrodes.…”

“…Another common design using extruded electrodes generate strong DEP forces, which improves throughput and affords better trapping efficiency up to a flow rate of 12 µL/min. Targeted cells such as HL-60 cell [ 157 ], polystyrene particles, drosophila cells [ 158 ], and viable yeast cells [ 155 , 159 ] are trapped by the electrodes in the microchannel with positive DEP while non-target cells are flushed to the outlet via negative DEP. Arrays of extruded electrode posts have been fabricated from gold [ 157 ], carbon [ 158 ] and highly doped silicon [ 160 ].…”

Insulator Based Dielectrophoresis: Micro, Nano, and Molecular Scale Biological Applications

“…Over the past 15 years, significant developments have been made in electrode manufacturing processes which have enabled the fabrication of three-dimensional passivated-electrodes [ 38 ], 3D printed metallic electrodes [ 39 ], and graphene electrodes [ 40 ]. These advancements have improved the manipulation efficacy of biological species at low applied electric fields, nurturing the varied frequency range process of microfluidic devices [ 38 , 41 ].…”