In vivo hydrogen ion sensor

Claim 1

An in vivo specific ion sensor which comprises a flexible metallic elongated electrode lead, an electrochemically active portion coating one end portion of said elongated electrode lead, an immobilized aqueous electrolyte coating the electrochemically active portion, said immobilized aqueous electrolyte containing at least two ions, one of said ions being the same as the ion to be detected and the second of said ions being one which enters into electrochemical equilibrium with the electrochemically active portion of said elongated electrode lead, a membrane barrier selectively permeable to the ionic species to be detected encapsulating the electrochemically active portion and the electrolyte coating, electrical insulation surrounding and adhering to said elongated electrode lead except for said electrochemically active portion coating one end portion of said lead and the opposite end portion of said lead, a tube having an opening at each end substantially in juxtaposition with said flexible elongated electrode lead and electrically insulated therefrom, the tube affixed to at least a portion of said electrical insulation, an ion-permeable membrane covering the opening at one end of the tube adjacent to and spaced from said encapsulating membrane barrier, an immobilized aqueous electrolyte contained within the tube, a metallic reference electrode element partially within the tube comprising a metallic electrode lead and an electrochemically active region, said electrochemically active region of the metallic reference electrode element being in contact with the electrolyte, a seal closing the opening at the opposite end of the tube, and a portion of the metallic reference electrode element forming a lead extending externally of the tube through said seal.