Iontophoresis device

1. An iontophoresis device having a working electrode structure, said working electrode structure comprising:

a first electrode;

a biological interface contact member including a substrate having a front surface and a rear surface, and a plurality of needles that protrude from the front surface of the substrate and which can be inserted into a biological interface, the needles including an ion exchange material that allows selective permeation of ions of a first polarity and substantially prevents permeation of ions of a second polarity, opposite to the first polarity; and

a drug holding part to hold a drug solution containing drug ions of the first polarity, the drug holding part interposed between the first electrode and the biological interface contact member, wherein the drug ions are driven through the ion exchange material of the needles from the drug holding part in response to an electrical potential applied via the first electrode.

2. The iontophoresis device according to claim 1 , wherein the biological interface contact member is formed of an ion-exchange membrane allowing selective permeation of the ions of the first polarity.

3. The iontophoresis device according to claim 2 , wherein holes are formed in the biological interface contact member, each of the holes extending from an inner portion of each of the needles to an opening at the rear surface of the substrate.

4. The iontophoresis device according to claim 2 , wherein the needles and the biological interface contact member are a unitary structure.

5. The iontophoresis device according to claim 1 , wherein the plurality of needles are a plurality of micro-needles.

6. The iontophoresis device according to claim 5 , wherein the needles are formed of the ion-exchange material.

7. The iontophoresis device according to claim 1 , wherein:

each of the needles having at least one hole formed therein, each of the holes communicating with a respective tip end of the needle; and

the ion exchange material includes an ion-exchange resin that fills at least a part of each of the holes, the ion-exchange resin having an ion-exchange group whose counter ion is of the first polarity.

8. The iontophoresis device according to claim 1 , wherein:

the plurality of needles are made of an ion-exchange resin introduced with an ion-exchange group whose counter ion is of the first polarity.

9. The iontophoresis device according to claim 1 , wherein the working electrode structure further includes:

a first electrolyte holding part for holding an electrolyte that is in contact with the first electrode; and

a second ion-exchange membrane that is interposed between the first electrolyte holding part and the drug holding part and allows selective permeation of ions of a second polarity, opposite to the first polarity.

10. The iontophoresis device according to claim 1 , further comprising a nonworking electrode structure including:

a second electrode;

a second electrolyte holding part for holding an electrolyte that is in contact with the second electrode;

a third ion-exchange membrane that is arranged on a front side of the second electrolyte holding part and allows selective permeation of the ions of the first polarity;

a third electrolyte holding part that is arranged on a front side of the third ion-exchange membrane and holds an electrolyte; and

a fourth ion-exchange membrane that is arranged on a front side of the third ion-exchange membrane and allows selective permeation of ions of a second polarity.