Do Earthing® Patches lose conductivity when they aren't sticky anymore?
If the adhesive on your individual Earthing® Patch isn't sticky anymore, this doesn't necessarily mean the Patch is no longer conductive.
What matters is that the gel in the center of the patch is still in contact with your skin. If it is, then the Patch is still conductive and you can use tape or Band-Aids or whatever works to keep the Patch on your body.
If the gel is no longer in contact with your skin, then discard the Patch and open a new one.
