Electroporation is an efficient tool to introduce nucleic acids into cells or tissues. Together with microfluidic technology, it offers several advantages, such as low but uniform electric parameter, in situ analysis. For clinical applications, there is a need to transfect a large number of cells (e.g. >109 cells). This is difficult to achieve using the current bulk electroporation device where the recommended cell population is around 105–106. A continuous electroporation device that could provide high cell throughput with a mild and uniform electro pulse would be highly desirable. In this presentation, a continuous converging microfluidic process is established for electroporation with high transfection efficiency and cell viability. When cells sequentially pass through the throat region of the converging microchannels, they will experience acceleration and a high electric field there, similar to a single electric pulse in the bulk electroporation process. Because of its continuous operation and the confinement of the microchannels, every cell experiences the same level of electroporation and, consequently, the delivery of therapeutic materials can be accomplished uniformly for a large number of cells. To gain the advantages of electric field localization and cell/gene confinement, cells and therapeutic materials are encapsulated in nanoporous microcapsules. Essentially, this is a three-dimensional analogy to a two-dimensional membrane-(cell/therapeutic materials)-membrane sandwich structure. It also shows that microencapsulated cells grow better than conventional methods, because of the in vivo-like microenvironment provided by the microcapsules.