Abstract:Sorting of particles such as cells is a critical process for many biomedical applications, and it is challenging to integrate it into an analytical microdevice. We report an effective and flexible dielectrophoresis (DEP)-based microfluidic device for continuous sorting of multiple particles in a microchannel. The particle sorter is composed of two components -a DEP focusing unit and a Movable DEP Trap (MDT). The trap is formed by an array of microelectrodes at the bottom of the channel and a transparent electrode plate placed at the top. The location of the trap is dependent on the configuration of voltages on the array and therefore is addressable. Flowing particles are first directed and focused into a single particle stream by the focusing unit. The streamed particles are then sorted into different fractions using the movable trap by rapidly switching the applied voltage. The performance of the sorter is demonstrated by successfully sorting microparticles in a continuous flow. The proposed DEP-based microfluidic sorter can be implemented in applications such as sample preparation and cell sorting for subsequent analytical processing, where sorting of particles is needed.

we developed a simple, low-cost and novel method for constructing three dimensional (3D) microelectrodes in biomedical devices by utilizing low melting point metal alloy. Three dimensional electrodes have unique properties in biomedical applications such as cell lysis, electroporation, dielectrophoresis, and detection. Compared to other fabrication methods for 3D electrodes, the presented one has many advantages, such as normal experiment conditions, simple processes and low-cost equipments. Numerical analysis on electric potential distribution with different electrode configurations was presented to verify the unique field distribution of arc-shape electrodes fabricated by our method. The application of 3D electrode made by high-conductivity metal alloy microspheres was confirmed by continuous particle sorting based on dielectrophoresis (DEP). The proposed technique offers alternatives to construct 3D electrodes from 2D planer electrodes in microfluidic devices.