Arraying single microbeads in microchannels using dielectrophoresis-assisted mechanical traps
Manipulating and immobilizing single microbeads in flowing fluids is relevant for biological assays and chemical tests but typically requires expensive laboratory equipment and trapping mechanisms that are not reversible. In this paper, we present a highly efficient and reversible mechanism for trapping microbeads by combining dielectrophoresis (DEP) with mechanical traps. The integration of planar electrodes and mechanical traps in a microchannel enables versatile manipulation of microbeads via DEP for their docking in recessed structures of mechanical traps. By simulating the combined effects of the hydrodynamic drag and DEP forces on microbeads, we explore a configuration of periodic traps where the beads are guided by the electrodes and immobilized in recess areas of the traps. The design of the electrode layout and operating configuration are optimized for the efficient trapping of single microbeads. We demonstrated the predicted guiding and trapping effectiveness of the design as well as the reversibility of the system on 10 μm polystyrene beads. Experimental verification used an array of 96 traps in an area of 420 × 420 μm2, reaching a trapping efficiency of 63% when 7 Vpp is applied to the electrodes under 80 nl min-1 flow rate conditions, and 98% of bead release when the voltage is turned off.