Electroporation in Microfluidic devices

Crossing the plasma cellular membrane for loading of exogenous substances or accessing the intracellular medium is essential for cell engineering and transfection, cell analysis, or controlled extraction of the cellular content. Various chemical and physical techniques have been developed to open up the cell membrane and allow molecular exchange between the extra- and intracellular environments. Electroporation, which relies on the use of a high external electric field to permeabilize the cell membrane, is the most popular physical technique: not only it avoids the use of viral material, but the cell transfection yield is also enhanced compared to chemical approaches. However, while electroporation is currently used on a daily basis for the transformation of a great variety of cells, it still suffers from a low success rate when it is performed in bulk in a cuvette, at the level of an mL-sized cell population. Furthermore, the use of high voltages in the kV range as required in such cuvettes gives rise to various issues, such as Joule heating, creation of bubbles through electrolysis of water, and generation of reactive species, which all compromise the success of the electroporation treatment. Using miniaturized and/or microfluidic devices helps solving these issues while enhancing the overall electroporation success rate, by bringing enhanced control on the process and requiring voltages as low as a few volts. In this chapter, after a short introduction to microfluidics, the unique features this technology can offer for cellular electroporation are discussed. Next, different classes of microfluidic devices for cell electroporation are presented, which are suitable for the treatment of individual cells or small cell populations. Finally, promising applications of microscale cellular electroporation are discussed.