Variable current density single needle electroporation system and method

Abstract

This invention comprises an improved electroporation electrode system comprising a single needle and a ring or donut shaped electrode wherein the difference in surface area of the electrodes provide for a substantial reduction of current density near the surface of the treated tissue and a more concentrated current density sufficient for electroporation only in tissues adjacent to the terminal portion of the single needle electrode. Thus, this invention provides for targeting specific tissue for electroporation and also should provide for lessening the sensation of electric current in the treated tissue.

What is claimed is: 
     
         1 . An electroporation device for delivering a molecule into cells of tissue, the electroporation device comprising:
 an electrical power source configured to deliver a pulse of energy;   a housing; and   an elongate needle electrode extending from the housing and in electrical communication with the electrical power source, the needle electrode having a proximal end and a distal end configured to pierce tissue, the needle electrode having a nonconductive portion and a conductive portion configured to deliver the pulse of energy to the tissue, the nonconductive portion being located between the proximal and distal ends,   wherein the needle electrode defines a plurality of apertures that are positioned on the conductive portion such that there are between approximately 10 and approximately 100 apertures per centimeter of length of the conductive portion, and the apertures are spaced around an entire circumference of the conductive portion and have a diameter in a range of 30 microns to 80 microns, wherein the aperture positioning, spacing, and diameters are configured to provide even distribution of an injection fluid over an entire length of the conductive portion.   
     
     
         2 . The electroporation device of  claim 1 , wherein the nonconductive portion is spaced from the distal end at a distance between 0.1 cm and about 2.5 cm.