Claims
- 1. A method for stimulating a neuron or neuron target cell which has a cell electropotential which is sensitive to the concentration of specific ion species at the exterior surface of its cell membrane or which has protein gate structures in its cell membrane which are sensitive or selective to one or more specific ion species, comprising of the steps of
providing at least one stimulating electrode and an ion-selective zone adjacent the cell membrane of the cell to be stimulated which selectively absorbs one or more of said ion species, selectively absorbing said ion species in the ion-selective zone to create a reservoir of such ionic species in the ion-selective zone or beneath it in an aqueous layer, and applying an electrical potential to the ion-selective zone to change the concentration of the ion species adjacent the cell membrane to induce a biological response in the cell.
- 2. A method accordance with claim 1 wherein said ion species is potassium, sodium, calcium, and/or chlorine ions, wherein the stimulating electrode is a metal, electrically conducting organopolymer, or semiconductor electrode, wherein the ionically selective zone is a layer of an organic or inorganic matrix containing an ionophore selective to the ion species, and wherein the potential applied to the ion-selective zone is between + or − three volts with respect to the cell exterior.
- 3. A method in accordance with claim 1 wherein the stimulating electrode is an electrically conducting organic polymer such as polypyrrole, polyaniline or polythiophene, and wherein the stimulating electrode itself also forms the ion-selective zone.
- 4. A method in accordance with claim 1 wherein the ion-selective zone is a potassium-ion selective layer having a thickness of from about 1 to about 20 microns, wherein potassium is selectively absorbed into the layer at a preferential ratio of at least about 5 times the amount of sodium ions absorbed into the layer, and wherein the potassium ion concentration adjacent the cell membrane is increased by at least 5 mM adjacent the cell membrane by the application of the electrical potential.
- 5. A method like that of claim 1, in which a cationic ion exchange resin layer (which is selective to cations over anions, but not primarily selective among cations) is used to form a cation-selective zone.
- 6. A method in accordance with claim 1 in which opposite polarities are applied to adjacent electrodes to produce electric field lines parallel to the cell membrane between such electrodes, and in which the pulsed application of stimulating potential to the cell membrane is peristaltically applied along the cell membrane by varying the potential along a series of electrodes disposed along the cell.
- 7. An ion-selective electrochemical synapse system for efficiently stimulating a functional neuron target cell or neuron target cell, comprising,
an electrically conductive electrode, a solid ion-selective reservoir layer positioned between the electrode and the adjacent cell, which is highly selective to a specific ionic species to provide a voltage-controllable reservoir of the specific ions in the ion-selective-reservoir layer, and a voltage source for varying the potential applied to the ion-selective reservoir layer to modulate (selectively expel from, or incorporate into) the amount of the selected ion in the selective layer and in a zone adjacent both the cell membrane and the ion-selective layer, to stimulate the target cell by a combination of electric field and ion concentration.
- 8. An electrochemical synapse system in accordance with claim 7 wherein the voltage source provides a pulsed potential in the range of from 0.5 to 3.0 volts with a rise time of less than 1 millisecond and for a duration of at least 1 millisecond, wherein the ions elective reservoir layer has a thickness of from about 2 to about 10 microns and an interconnected porosity of at least about 5 volume percent, wherein the ion-selective reservoir layer is positioned within about 10 microns of the cell membrane surface zone to be stimulated, and wherein the ion-selective layer is selective to potassium ions.
REFERENCE TO PRIORITY APPLICATIONS
[0001] This application claims priority based on Provisional Application No. 60/216,224 filed Jul. 5, 2000 and PCT/US01/21233 filed Jul. 3, 2001.