Sensor elements with a tantalum- or niobium-containing base layer and methods of producing the same

Abstract

Sensor elements are disclosed for the electrochemically analyzing a body fluid, as well as methods of producing and using the same. The sensor elements include an electrically conductive layer structure applied to a non-conductive carrier substrate, where the layer structure includes a continuous base layer of tantalum, niobium or an alloy thereof, and a metallic cover layer formed on the base layer that covers the base layer either over the entire surface or in some regions. The metallic cover layer includes a more noble metal when compared to the base layer.

The invention claimed is: 
     
         1 . A sensor element for electrochemically analyzing a body fluid sample, the sensor element comprising:
 an electrically insulating carrier substrate; and   an electrically conductive layer structure deposited on a surface of the carrier substrate, wherein the electrically conductive layer structure comprises a continuous base layer of tantalum, niobium or an alloy thereof and a metallic cover layer formed on the base layer covering the base layer over an entire surface of the base layer or in some regions thereof, wherein the cover layer is a more noble metal when compared to the base layer, and wherein the electrically conductive layer structure includes an electrode arrangement to the which the body fluid sample can be applied.   
     
     
         2 . The sensor element of  claim 1 , wherein the cover layer covers about 5% or more of the total area of the base layer. 
     
     
         3 . The sensor element of  claim 1 , wherein the base layer has a greater layer thickness than the cover layer. 
     
     
         4 . The sensor element of  claim 1 , wherein the base layer has an essentially constant layer thickness in the range of about 50 nm to about 200 nm. 
     
     
         5 . The sensor element of  claim 1 , wherein the cover layer has a layer thickness of less than about 50 nm. 
     
     
         6 . The sensor element of  claim 1 , wherein the cover layer has a layer thickness of less than about 20 nm. 
     
     
         7 . The sensor element of  claim 1 , wherein the base layer includes a bonding agent for the cover layer, and wherein the bonding agent has a layer thickness of at least about 0.5 nm and less than about 20 nm. 
     
     
         8 . The sensor element of  claim 1 , wherein the base layer is entirely tantalum. 
     
     
         9 . The sensor element of  claim 1 , wherein the cover layer is a noble metal selected from the group consisting of gold, palladium, platinum and alloys thereof. 
     
     
         10 . The sensor element of  claim 9 , wherein the noble metal is gold. 
     
     
         11 . The sensor element of  claim 1 , wherein the electrode arrangement, and where appropriate, a region of contact to an electrical connection of the electrode arrangement are formed from metals in two layers. 
     
     
         12 . The sensor element of  claim 1 , further comprising a reagent system for electrochemically detecting an analyte in the sample, wherein the reagent system is arranged in a region of the electrode arrangement. 
     
     
         13 . The sensor element of  claim 12 , wherein the reagent system is configured for glucose, lactate or prothrombin time testing. 
     
     
         14 . A method of producing an electrochemical sensor element, the method comprising the steps of:
 depositing an electrically conducting layer structure on an electrically insulating carrier substrate, wherein the electrically conducing layer structure is formed from a continuous base layer of tantalum, niobium or an alloy thereof and at least in some areas of a cover layer formed on the base layer of a more noble metal when compared to the base layer.   
     
     
         15 . The method of  claim 14 , wherein the base layer is firstly applied to the carrier substrate and the cover layer is secondly applied to the base layer, each by a coating process. 
     
     
         16 . The method of  claim 14 , wherein the base layer and the cover layer are formed by sputter deposition. 
     
     
         17 . The method of  claim 14 , wherein the base layer and the cover layer are successively sputtered on in a vacuum chamber without interrupting a vacuum. 
     
     
         18 . The method of  claim 14 , wherein the cover layer is applied to the base layer through a mask or aperture in a strip shape. 
     
     
         19 . The method of  claim 14 , wherein the base layer and the cover layer are geometrically structured by removing material from sections by laser ablation. 
     
     
         20 . The method of  claim 14 , wherein the base layer is tantalum and the cover layer is gold.