GB1486520A - Cathode for polarographic measurements in physiological media - Google Patents

Abstract

1486520 Oxygen sensing electrode SIEMENS AG 15 April 1975 [16 April 1974] 15532/75 Heading G1N An electrode for physiological measurements comprises a precious metal wirel covered by organic polymeric insulation material 2 and an oxygen permeable membrane 4 over one end of the wire. The other end of the wire is for connection to equipment by soldering or clamping. The insulation covered wire can be cut from a longer length thereof. A further layer of insulation 3 may be formed by pressing two sheets of material around insulation 2 and moulding to the desired shape. A cavity 5 for electrolyte 6 or membrane alone may be formed by etching or the membrane may cover the end of wire and insulation. The wire is preferably of gold or platinum with a diameter of 10-100Ám, preferably 60Ám. The inner insulation 2 may be a polyurethane lacquer, the outer layer a body compatible polymer, the membrane PTFE and the electrolyte sodium chloride solution. In other embodiments, the insulation may incorporate textile fibre reinforcement and may contain a passage (lumen) for drawing off specimens or flushing the electrode tip. The passage exit may be at either the end or side of the electrode. A rubber bladder, inflatable by an additional lumen may be provided near the electrode tip for centering in a blood vessel. An annular reference electrode may be attached round the oxygen electrode with connection to another wire in the insulation body. The electrode may be injected into the body by a cannula or may be pushed into a blood vessel when associated with a catheter.