Urea biosensor for hemodialysis monitoring

A urea biosensor adapted for hemodialysis using a solid state pH electrode including:

• a sensor element comprising:
• a substrate;
• a film of adhesion material on a surface of the substrate;
• a layer of iridium on the film of said adhesion material;
• a layer of iridium oxide on at least a portion of the layer of iridium, said iridium oxide layer being wider than said iridium layer and extends over at least one end of said iridium layer;
• and
• a coating of urease containing material deposited over and covering the layer of iridium oxide.

A method of fabricating a sensor element for a urea monitoring, comprising:

• providing a substrate;
• forming a metal layer on at least a portion of the substrate;
• depositing a layer of pH-sensitive oxide on at least a section of the metal layer, the pH sensitive layer being wider than the metal layer and extends over at least one end of the metal layer;
• and
• forming a coating of urease containing material over said layer of pH-sensitive oxide.