Hybrid dielectrophoresis devices that employ electrically floating electrodes

In current devices, dielectrophoresis (DEP) is implemented by connecting microelectrodes to external voltage signals. This study presents an alternative approach for implementing DEP in which some electrodes are left electrostatically floating. It is demonstrated experimentally and theoretically that these electrodes produce effective DEP forces. Floating electrodes do not require a connection to an external signal. Therefore, DEP devices can be constructed as hybrids of excited microelectrodes and floating nanoelectrodes. This approach can overcome the significant difficulties involved in connecting nanoelectrodes to an external signal. The study demonstrates that floating nanoelectrodes can increase local DEP forces by at least three orders of magnitude without having to increase the voltages applied to the excited microelectrodes. Therefore, floating nanoelectrodes can significantly broaden the range of DEP devices capable of manipulating nanoparticles. Moreover, floating nanoelectrodes enable nanoparticles to be manipulated with nanometer spatial resolution. As a result, hybrid devices that employ floating nanoelectrodes may make bottom-up DEP fabrication possible. (c) 2007 Elsevier B.V. All rights reserved.