A reference electrode consisting of a metal in contact in contact with an
electrolyte containing an anion or cation whose concentration in part
determines the redox potential of the electrode? This electrolyte
contains a polyelectrolyte that partially and reversibly binds this
chemical cation or anion thus lowering the free concentration of the
cation or anion compared to the osmotic pressure of the same
concentration of cation or anion if present as a simple salt. The
polyelectrolyte can be anionic or cationic depending on the chemistry of
the redox electrode and a thickener may also be added to the electrolyte.