A systematic design and miniaturization of conventional clinical and diagnostic tools are emerging in many nanobiotechnology and nanobioscience fields. Recently, the pharmaceutical and biotechnological industries have continuously accelerated novel drug discovery for cellular therapeutics of hard-to-cure diseases. Electroporation is a promising candidate in gene transfection methods for future cellular therapeutics. Here, we report our initial study on the effect of geometry on impedance of cell suspended media in electroporation using a microchannel. A full understanding of the electroporation environment and conditions enabled us to optimize protocols of electroporation for various cell lines efficiently. Furthermore, this study will open up a new vista of future electroporation devices using microstructures. (C) 2007 Elsevier B. V. All rights reserved.