Abstract: A long term analyte sensor for measuring at least one analyte in the body of a user and which includes a housing, a plurality of analyte contacting sensor elements and at least one structure for relaying information away from the sensor. This plurality of analyte contacting sensor elements are typically disposed in an array. The analyte sensor further includes at least one sensor protection membrane that is controllable in a manner such that sensor elements may be activated (e.g. exposed to the external environment) at different times so as to extend the useful life of the sensor. In illustrative analyte sensors, the analyte is glucose.

Abstract: Apparatus for removing substances from blood is disclosed. The apparatus includes concentric cylinders defining an annulus therebetween with the inner cylinder adapted for rotation with respect to the outer cylinder. At least one of the cylinders includes a porous membrane covered portion forming a compartment containing an immobilized active species. The active species is adapted to break down or remove the substance. Plasma in blood flowing in the annulus passes through the porous membrane and interacts with the active species either by reaction or binding. Red and white blood cells do not pass through the membrane. In this way, a substance is removed from plasma without exposing blood cells to the active species.