Apparatus and method for electroporation of tissue

• US 5,983,131 A
• Filed: 08/09/1996
• Issued: 11/09/1999
• Est. Priority Date: 08/11/1995
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Vaughan, Timothy, Weaver, James C., Pliquett, Uwe
• Primary Examiner(s): Bockelman, Mark
• Application Number:
  US08/695,032
• Time in Patent Office: 1,187 Days
• Field of Search: 604/20-21, 435/173.5-173.6, 607/153
• US Class Current: 604/20
• CPC Class Codes: A61N 1/0424 Shape of the electrode
• CPC Class Codes: A61N 1/044 Shape of the electrode
• CPC Class Codes: A61N 1/327 for enhancing the absorption properties of tissue, e.g. by electroporation

Abstract

The present invention relates to an apparatus and method for localized electroporation of tissue. An apparatus includes a perforate electrically insulating layer, a first electrode at a first side of the perforate electrically insulating layer and a second electrode at a second side of the perforate electrically insulating layer. An electric field extending between the first and second electrodes will preferentially extend through perforations of the electrically insulating layer. The electric field thereby causes electroporation of tissue that is proximate to the first electrode and is partitioned from the electrically insulating layer and the second electrode by the first electrode. The apparatus controllably limits the depth of the electric field within a tissue, such as skin, thereby electroporating a surface layer, such as a stratum corneum layer of the skin, without stimulating submerged nerve endings within the skin. Sensation of the applied voltage and especially pain sensation can thereby be controlled by the invention.

Claims

1. An apparatus for electroporating a tissue, comprising:

a) a perforate electrically insulating layer;

b) at least one first external electrode contacting a first side of said perforate electrically insulating layer;

c) a second electrode having a first surface and an opposite second surface, said second surface being located at a second side of said perforate electrically insulating layer, whereby an electric field extending between said first and second electrodes will preferentially extend through perforations of said electrically insulating layer, said electric field thereby causing electroporation of a tissue that is proximate to said first electrode and is partitioned from said electrically insulating layer and said second electrode by the first electrode; and

d) means for conducting a fluid from the first surface of the second electrode to the second surface of said second electrode.

2. The apparatus of claim 1, wherein said first electrode is a plurality of first electrodes, whereby said first electrodes are electrically insulated from each other.

3. The apparatus of claim 1, wherein said first electrode is perforate.

4. The apparatus of claim 3, wherein at least a portion of perforations in said first electrode are substantially aligned with at least a portion of perforations of said electrically insulating layer.

5. The apparatus of claim 4, wherein said first electrode and said perforated electrically insulating layer are in contact with each other at said aligned perforations, whereby said aligned perforations can contain a material to be conducted into electroporated tissue at the first electrode.

6. The apparatus of claim 5, wherein said perforations of the first electrode have a larger diameter than diameter of perforations of the perforate electrically-insulating layer.

7. The apparatus of claim 5, further including a housing for containing a material to be directed into electroporated tissue at the first electrode, said housing defining an application opening at which the first electrode is located, said electrically insulating layer and said second electrode being contained by said housing and said first electrode.

8. The apparatus of claim 7 wherein said housing further defines an inlet for introduction of a material into said housing.

9. The apparatus of claim 8, further including a filter element located between said electrically insulating layer and said second electrode.

10. The apparatus of claim 9, further including an electrical resistance measurement means, comprising:

a) an electrical resistance measurement component;

b) a first electrical resistance measurement electrode connected to the electrical resistance measurement component and located at said housing; and

c) a second electrical resistance measurement electrode for contact with the tissue and connected to said electrical resistance measurement component.

11. The apparatus of claim 9 further including means at said housing for pressurizing a material within said housing.

12. The apparatus of claim 11 wherein said means includes an ultrasound device.

13. The apparatus of claim 9 further including means for directing material into said housing.

14. The apparatus of claim 13 wherein said means includes a syringe at said housing.

15. The apparatus of claim 10, further including a switching means at said first and second electrodes for switching between application of an electric field and measurement of electrical resistance at the tissue.

16. An apparatus as in claim 1 wherein said first electrode is at least partially coated by a second electrically insulating layer.

17. A method for electroporating a tissue, comprising the steps of:

a) contacting at least one first electrode to the tissue;

b) forming an electric field between said first electrode and a second electrode that is partitioned from said first electrode by a nonconductive layer that contacts the first electrode, whereby said electric field preferentially extends around at least a portion of said insulating layer, the electric field thereby causing electroporation of tissue that is proximate to the first electrode; and

c) forming a plurality of electric fields, each electric field being formed between a first electrode and the second electrode.

18. The method of claim 17 wherein said electric fields are formed sequentially to selectively designate at least one first electrode that is most proximate to a preferred location at said tissue for electroporation.

19. A method for causing iontophoresis in a tissue, comprising the steps of:

a) contacting a least one first electrode to the tissue;

b) forming an electric field between said first electrode and a second electrode that is partitioned from said first electrode by a nonconductive layer that contacts the first electrode, whereby said electric field preferentially extends around at least a portion of said insulating layer, the electric field thereby causing iontophoresis of tissue that is proximate to the first electrode; and

c) directing a material from a first surface of the second electrode to a second surface of the second electrode and into iontophoresed tissue proximate to said first electrode.

20. A method of claim 19 wherein said electric field is formed by applying a voltage between said electrodes in a range of between about 0.1 volts and five volts.