Controlling two-dimensional movement of microparticles over an electrode array surface.

This paper presents an original microchip device that manipulates planar x- and y-positions of dielectric microbeads over an electrode array with dielectrophoresis (DEP) effects. Implemented with a simple single-layer metal process, the microchip device consists of two parallel arrays of triangular-shaped electrodes. The two arrays of electrodes are arranged such that they locked into each other to form interdigitated electrodes. The unique geometry and placement of the electrodes can produce different configurations of DEP waveforms. The different DEP waveforms will, in turn, allow the strength and the locations of the electric field maxima and minima to be manipulated. Our experiments showed that with a quad-pole traveling wave, the microbeads can be moved across the electrode array surface in directions parallel to the fluid flow to establish their x-positions via traveling wave dielectrophoresis (TWD) effect. In addition, the microbeads can be moved in directions perpendicular to the fluid flow to establish their y- positions via activating one or both sets of electrode arrays with DEP waveforms. A line of microbeads can be held indefinitely at the predetermined location or be immediately moved to an arbitrary location on the electrode array. With a functional transportation of particles along two planar axes, the "teeth-like" electrode structure can be easily integrated into a microfluidic system where an accurate position control of particles is required.