US Patent 8008063 Individual-cell electroporation using area-focused electric fields

Electroporation is performed on a population of cells, liposomes, vesicles, or other membrane-encased structures with uniform results regardless of size variations within the population, by drawing the membrane-encased structures into micron-sized openings that contain paired electrodes. An electric potential is then imposed between the paired electrodes to permeabilize only that portion of each cell that extends into the openings and resides within the electric field focused in the area between the electrodes.