Electrochemical sensor

Abstract

An electrochemical sensor comprising a probe immersible in a measured medium and having at least two electrodes of a first electrically conductive material and at least one probe body of a second, electrically non-conductive material. The electrodes are at least partially embedded in the probe body and insulated from one another by the probe body, wherein the at least two electrodes are embodied of at least one conductive material and the probe body of at least one electrically insulating ceramic, wherein the electrodes are embodied of thin, measuring active layers of a conductive material and sit in an end face of the probe body of a ceramic material, and wherein the electrodes are electrically contacted via connection elements extending through the probe body.

What is claimed is: 
     
         1 . A probe for an electrochemical sensor, comprising:
 a probe body embodied of an electrically insulating ceramic, the probe body having a cross-sectional area and a length;   at least two electrodes composed of an electrically conductive material, the at least two electrodes embedded in the probe body and insulated from each other by the probe body, wherein each electrode is embedded in a corresponding cavity in an end face of the probe body such that an outer surface of each electrode is flush with the end face of the probe body and each electrode fills the corresponding cavity; and   at least two connection elements, each connection element electrically connected to a corresponding electrode of the at least two electrodes and extending through the length of the probe body from the corresponding electrode,   wherein the probe is produced by
 producing a green probe body of the electrically insulating ceramic, 
 pressing each electrode connected to its corresponding connection element into its corresponding cavity in the green probe body, and 
 sintering together the green probe body, the at least two electrodes, and the at least two connection elements, 
   wherein the sintering produces a material bonding between the electrodes and the probe body making a gap-free material transition between each electrode and the probe body.   
     
     
         2 . The probe of  claim 1 , wherein a thermal coefficient of expansion of the electrically insulating ceramic and a thermal coefficient of expansion of the electrically conductive metal differ by not more than 2×10 −6  K −1 . 
     
     
         3 . The probe of  claim 1 , wherein the electrically insulating ceramic is one of a zirconium oxide (ZrO 2 ) ceramic, an aluminum oxide (Al 2 O 3 ) ceramic, a chromium oxide (Cr 2 O 3 ) ceramic, a titanium dioxide (TiO 2 ) ceramic, and a tialite (Al 2 TiO 5 ) ceramic. 
     
     
         4 . The probe of  claim 1 , wherein the electrically conductive material is one of electrically conductive ceramic, electrically conductive enamel, platinum, titanium, and stainless steel. 
     
     
         5 . The probe of  claim 1 , wherein the electrically conductive material is platinum and the electrically insulating ceramic is zirconium oxide ceramic stabilized with magnesium. 
     
     
         6 . The probe of  claim 1 , further comprising:
 a temperature sensor disposed within the probe body and attached to the probe body using a thermally conductive adhesive.   
     
     
         7 . The probe of  claim 1 , wherein each electrode has thickness defined in the direction of the length of the probe body and the thickness of each electrode is from 10 micrometers (μm) to 3 millimeters (mm). 
     
     
         8 . An electrochemical sensor, comprising:
 a probe, comprising:
 a probe body embodied of an electrically insulating ceramic, the probe body having a cross-sectional area and a length; 
 at least two electrodes composed of an electrically conductive material, the at least two electrodes embedded in the probe body and insulated from each other by the probe body, wherein each electrode is embedded in a corresponding cavity in an end face of the probe body such that an outer surface of each electrode is flush with the end face of the probe body and each electrode fills the corresponding cavity; and 
   at least two connection elements, each connection element electrically connected to a corresponding electrode of the at least two electrodes and extending through the length of the probe body from the corresponding electrode,
 wherein the probe is produced by
 producing a green probe body of the electrically insulating ceramic, 
 pressing each electrode connected to its corresponding connection element into its corresponding cavity in the green probe body, and 
 sintering together the green probe body, the at least two electrodes, and the at least two connection elements, 
 
 wherein the sintering produces a material bonding between the electrodes and the probe body making a gap-free material transition between each electrode and the probe body; and 
   a measuring electronics connected to the at least two connection elements and embodied to determine an electrochemical property of a liquid medium.   
     
     
         9 . An electrochemical sensor comprising:
 a probe immersible in a measured medium, the probe comprising:
 a probe body composed of an electrically insulating ceramic, the probe body having a longitudinal axis, 
 at least two electrodes and a corresponding connection element for each electrode, each electrode electrically connected to its corresponding connection element and each electrode embodied as a layer of electrically conductive material having a thickness defined in the direction of the longitudinal axis, the thickness being in a range from 10 micrometers to 3 millimeters, 
 wherein the at least two electrodes and the corresponding connection elements are at least partially embedded in the probe body and insulated from one another by the probe body, and the at least two electrodes are disposed in an end face of the probe body such that an end face of each electrode is flush with the end face of the probe body, 
   wherein each electrode is electrically connected to its corresponding connection element and each connection element extends from its corresponding electrode through the probe body, and   wherein the probe body and the electrodes are formed such that intermolecular interactions between the electrically conductive metal and the electrically insulating ceramic provide a material bonding between the electrodes and the probe body and a gap-free material transition between the electrodes and the probe body.   
     
     
         10 . The electrochemical sensor of  claim 9 , wherein the electrically insulating ceramic is one of a zirconium oxide (ZrO 2 ) ceramic, an aluminum oxide (Al 2 O 3 ) ceramic, a chromium oxide (Cr 2 O 3 ) ceramic, a titanium dioxide (TiO 2 ) ceramic, and a tialite (Al 2 TiO 5 ) ceramic. 
     
     
         11 . The electrochemical sensor of  claim 9 , wherein the electrically conductive material is one of electrically conductive ceramic, electrically conductive enamel, platinum, titanium, and stainless steel.