Why do we have surface charges on a polymer sheet immerged in water ?
Answers
I've started exploring electrical double layers and electrode-tissue interfaces whilst dealing with deep brain stimulation and stimulus artefact. I've heard many times that what causes the double layer to form is a net charge at the surface of the submerged electrode that then quickly attracts ions (cations or anions depending on the surface charge sign).
I always thought that in general, objects are neutral and don't carry charge around, where then, does the surface charge on electrodes come from?
his can be answered on more than one level. Where did the word "electrode" come from, to begin with? Supposedly it is due to the fact that you apply some electric potential to that metal needle (stuck into the brain of some creature or other electrolytic medium), and that's why the electrode gets charged.
Electrode potential appears at the interface between an electrode and electrolyte due to the transfer of charged species across the interface, specific adsorption of ions at the interface, and specific adsorption/orientation of polar molecules, including those of the solvent.