Electrokinetic Assembly of Microsphere and Cellular Arrays

We have developed a novel electrochemical system for field assisted, fluidic assembly of objects on a microfabricated silicon substrate by means of electrical addressing. The principle of our technique is based on the movement of charged species in solution to oppositely charged electrodes, as seen commonly in electrophoresis. Here, charged species such as beads and cells are moved electrokinetically through an aqueous solution towards a charged electrode. Micro patterning of the electrodes allows localization of charged species. We present a theoretical framework to predict the electric potential for assembly and disassembly of spherical objects. We correlate theoretical predictions with the motion of negatively charged polystyrene beads of 20 μm diameter on 100 μm feature micro patterned substrates. In addition, we extended these results to arraying of 20-30 μm diameter live mammalian cells by means of electrical addressing. This technique has applications in creation of ‘active’ cellular arrays for cell biology research, drug discovery and tissue engineering.