this invention pertains to the concept of creating a strip that contains one or more amperometric biosensing electrodes and integrating this strip into the outer wall of a hollow catheter . the electrodes can be used for continuous sensing of an analyte such as glucose and the hollow lumen can be used concurrently for delivery of a drug such as insulin . there is a risk for electrode films to break apart during impact . however , if there is a metallic foil beneath the thin film metal electrodes , durability and fatigue resistance are markedly improved . the term “ foil ” indicates a metal layer that is 2 - 15 μm in thickness . foils can be created by rolling , hammering , electroplating , printing , or vacuum - deposition . a foil - polymer laminate is suitable as a substrate because it permits low - cost patterning and assembly into a durable , fatigue - resistant sensor .