Abstract: A sterilizable electrode employs a selectively permeable membrane bonded at its edges to a face of a cover member. An opening or hole in the cover permits contact between the membrane and a material whose composition is to be tested. The cover and membrane assembly are removably attached to an electrolyte filled sensor body which also houses an electrode. The electrode is arranged to bear against the membrane to force the latter to bulge into the hole of the cover. In a dissolved oxygen sensor embodiment the electrode is a body of silver connected to a silver wire which extends through an inert, insulating sheath. The sheath is contained within a stainless steel shield which serves as the electrical conductor to, and a supporting structure for, a lead anode.

Abstract: Included in the body of ion sensitive and selective electrodes and reference electrodes is a plug which engages the electrolyte and yields and reforms with expansion and contraction of the electrolyte body. The plug maintains pressure on the electrolyte eliminating air and preventing the formation of bubbles. The result is an electrode which is useful in any spacial orientation and which has an extended upper limit temperature operating range.

Abstract: An ion sensitive electrode structure employing concentrically arranged inner and outer tubular members employs a porous plug to seal the annular space between the tubular members and to enable formation of a salt bridge. The plug is made of porous Teflon and, in preferred form, it is combined with an encompassing sealing annulus which seals an annular space between the outer wall of the plug and the inner wall of the outer tubular member. In a form preferred for some applications, two such plugs and sealing annulus' are employed and are held separated by a spacer.