An electrode system include a flowable and cohesive surface contact element comprising a hydrophilic polymer swollen with an electrolyte fluid, the contact element having a Q′ ratio of at least 5 as defined by the equationQ′=WWWGwherein WG is the dry weight of the hydrophilic polymer and WW is weight of water in the sample after absorption of the electrolyte fluid comprising water and an electrolyte salt. The surface contact element can consist essentially of the hydrophilic polymer swollen by the electrolyte fluid. Another electrode system includes a contact element including a crosslinked hydrophilic polymer matrix. The contact element has a Q′ ratio of at least 5 as defined by the equationQ′=WWWG.The contact elements can also have a Q′ ratio of at least 6, at least 7, at least 10 or even at least 11.
