Disclosed is a method for penetration of lipid bilayer membranes in order
to insert at the tip of a hollow needle-shaped object, such as a
micropipet-, into a container formed of a lipid bilayer membrane, wherein
said container is placed between said needle-shaped object, with the tip
of said needle-shaped object placed in contact with said conainer in such
a way that it applies a mechanical force to the lipid membrane of said
container, thus mechanically straining it, and a second electrode,
whereupon a transient electric pulse of 1-to-10.sup.3 V/cm is applied
between the electrodes, resulting in a focused electrical field over said
container C which induces a dielectric breakdown of the lipid bilayer
causing the needle-shaped object to penetrate the container. Disclosed is
also an electroinjection method based on the above method, wherein
substances are introduced through the needle-shaped object and into the
container after penetration of the needle-shaped object.