. . . "The opposed element electrodes 202, 204 can be composed of an ordinary conductive material, that can be selected, for example, from a metal such as Ni, Cr, Au, Mo, W, Pt, Ti, Al, Cu, Pd or an alloy thereof, a printed conductor composed of a metal or a metal oxide such as Pd, Ag, Au, RuO2 or Pd???Ag and glass, a transparent conductive material such as In2O3???SnO2, or a semiconductive material such" . .