It is the diameter of the end of the needle that is used to inject the size of the cell jets. For they have overcome it. This new technique is called electrodynamic jet and consists of passing a liquid suspension of human cells on a 500 micron diameter needle with a certain flow rate. Applying the electrical voltage, the liquid comes loaded and after leaving the needle drops form. The diameter of these drops is much smaller than that of the end of the needle, a few microns.