Dry electrodes for transcutaneous nerve stimulation

Abstract

Disclosed herein are systems, devices, and methods for peripheral nerve stimulation, particularly for treating tremor. The nerve stimulation may be accomplished by a wearable nerve stimulation device, such as a band configured to be worn on the wrist or other body part. The device can accomplish targeted nerve stimulation using circumferentially spaced electrodes. In some embodiments, the device may use only the same number of electrodes as the number of nerves that are to be stimulated. A biphasic charge-balanced waveform may be used to selectively stimulate a nerve near one of the activated electrodes but not to stimulate the nerve near the other activated electrode. The device may use dry electrodes for long-term, repeated use. The dry electrodes may include a conductive base layer and a polymeric, plastic or rubber skin contact layer comprising a conductive filler. The filler may be a powder, fiber, conductive coating, etc.

What is claimed is: 
     
         1 . A dry electrode for transcutaneous electrical stimulation, the dry electrode comprising:
 a conductive backing layer; and   a skin contact layer disposed on the conductive backing layer, the skin contact layer comprising a polymer, plastic, or rubber material, and a conductive filler material dispersed substantially evenly throughout the polymer, plastic, or rubber material, wherein the skin contact layer has a skin facing surface that is not coated with a hydrogel or liquid.   
     
     
         2 . The dry electrode of  claim 1 , wherein the conductive backing layer comprises a metal foil. 
     
     
         3 . The dry electrode of  claim 2 , wherein the metal foil is disposed on a flexible polymer substrate. 
     
     
         4 . The dry electrode of  claim 1 , wherein the conductive filler material comprises a powder or fine particulate material. 
     
     
         5 . The dry electrode of  claim 1 , wherein the conductive filler material comprises metal, carbon, or a mixture thereof. 
     
     
         6 . The dry electrode of  claim 1 , wherein the conductive layer comprises porous material treated with a conductive coating. 
     
     
         7 . The dry electrode of  claim 1 , wherein the skin contact layer has a Shore hardness between about 10 A to about 100 A. 
     
     
         8 . The dry electrode of  claim 1 , wherein the skin contact layer has a volume resistivity between about 1 ohm*cm and about 2000 ohm*cm. 
     
     
         9 . The dry electrode of  claim 1 , wherein the measured resistance or conductance at a plurality of points across the skin facing surface of the skin contact layer has a standard deviation of within about 50% of the average measured resistance or conductance. 
     
     
         10 . The dry electrode of  claim 1 , wherein the skin contacting layer comprises silicone. 
     
     
         11 . A dry electrode for transcutaneous electrical stimulation, the dry electrode comprising:
 a conductive backing layer; and   a skin contact layer disposed on the conductive backing layer, the skin contact layer comprising a polymer, plastic, or rubber material, and a conductive filler material dispersed substantially evenly throughout the polymer, plastic, or rubber material, wherein the conductive filler material comprises silver coated glass bubbles or single wall carbon nanotubes,   wherein the skin contact layer has a skin facing surface that is not coated with a hydrogel or liquid,   wherein the dry electrode has a bulk resistivity of between about 50 ohm-cm and about 1,000 ohm-cm,   wherein the skin contact layer has a Shore A durometer of between about 30 A and about 50 A,   wherein the homogeneity of the conductive filler material is such that there is less than about a 5% difference in resistivity across the skin contact layer.   
     
     
         12 . The dry electrode of  claim 11 , wherein the skin contact layer comprises silicone. 
     
     
         13 . The dry electrode of  claim 11 , wherein the conductive filler material comprises silver coated glass bubbles. 
     
     
         14 . The dry electrode of  claim 11 , wherein the conductive filler material comprises single wall carbon nanotubes. 
     
     
         15 . The dry electrode of  claim 13 , wherein the loading of silver coated glass bubbles is between about 3% and about 30% of the skin contact layer. 
     
     
         16 . The dry electrode of  claim 14 , wherein the loading of single wall carbon nanotubes is between about 1% and about 5%. 
     
     
         17 . A method of delivering transcutaneous electrical stimulation to a person, comprising:
 providing a wearable device comprising at least 2 dry electrodes comprising a conductive backing layer, and a skin contact layer comprising a polymer, plastic, or rubber material and a conductive filler material dispersed substantially evenly throughout the polymer, plastic, or rubber material, the skin contact layer further comprising a conductive filler material dispersed substantially evenly throughout the polymer, plastic, or rubber material;   positioning the skin contact layer of the dry electrodes on desired locations on the skin, wherein the polymer, plastic, or rubber material is in direct contact with the skin; and   activating the device, thereby delivering electrical current through the dry electrodes to the desired locations on the skin.   
     
     
         18 . The method of  claim 17 , wherein the desired locations are adjacent one or more target nerves.