Optimized micro devices for liquid-dielectrophoresis (LDEP) actuation of conductive solutions

Liquid dielectrophoresis (LDEP) technique is known to displace liquids in open environments by applying alternating or DC voltages between electrodes patterned below a single or a stack of dielectric layers. This technique is able to handle pico–nano liter droplets and could be used to carry out biological and chemical protocols. According to the electrode geometry, the dielectric layers constants and thicknesses, this technique may require relatively high actuation voltages (∼200–500 VRMS). In addition, most of experiments carried out in the literature have shown the LDEP technique to be more adapted to insulating or semi insulating liquids (lower than 1 mS m−1). This paper reports optimization of LDEP devices, in terms of miniaturization (generation of droplets arrays with droplets size ranging from 0.5 pL to 0.1 nL), and choice of dielectric materials. Following this procedure we have successfully addressed two challenging constraints in the field of LDEP: firstly deionized water can be actuated with operating voltages below 150 VRMS and secondly solutions with conductivity up to 10 mS m−1 have been partly displaced. These results allow us to foresee manipulation of organic solutions, biological buffers by LDEP at the micro-nanoscale, which will attract strong interest for sample preparation in complex biochemical protocols.