A 3-D microelectrode system for handling and caging single cells and particles

We have designed and constructed several designs of 3-D microelectrode systems consisting of two layers of electrode structures separated by a 40 mu m thick polymer spacer forming a flow channel. The electrode elements such as funnel, aligner, cage and switch are driven by alternating current (AC) and/or rotating electric fields. They are designed to focus, trap and separate eukaryotic cells (Jurkat) or latex particles with a diameter of 10-30 mu m using negative dielectrophoresis (nDEP). The electrode width is similar to 10 mu m and active electrode surfaces have been minimised in order to reduce heating of the solution. A more flexible employment of the different electrode elements was realised by working with up to three generators, and/or a laboratory-made distribution box. The electrodes of the funnel, aligner or switch were operated with 5-11 V at 5-15 MHz, efficient handling of particles could be achieved with flow rates up to 3500 mu m/s. Cells could be aligned effectively at flow rates up to 300 mu m/s in PBS. Latex particles could be retained within the dielectric held cages (DFC) or aligner against a laminar flow of 40-200 mu m/s using an amplitude of 8 V at 5-15 MHz. Cells could be held at flow rates up to 50 mu m/s. Numerical calculations for dielectric forces and the induced membrane potential in held cages are given for solutions of different conductivities at different applied frequencies. (C) 1999 Elsevier Science S.A. All rights reserved.