Patent ID: 6721587
Filing Date: 2004-04-13
Classification: A61B

Abstract:
A measuring device for determining the concentration of a first molecule in an environment, which first molecule reacts in presence of a catalyst within the device, with a second molecule to form a third molecule; the measuring device comprising:(a) a membrane comprising: (1) a body permeable to said second molecule ad essentially impermeable to said first molecule; and (2) at least one discrete hydrophilic region in communication with the body, which hydrophilic region contains the catalyst and is permeable to both the first and second molecules; (i) wherein the direction of diffusion of the second molecule into the body is substantially parallel to the direction of diffusion of both the first and second molecules into the hydrophilic region; (b) at least one critical zone coincident with the hydrophilic region, or a portion thereof, which critical zone has an average equivalent radius and a length, (1) wherein the average equivalent radius of the critical zone is less than its length, and (2) wherein further an average vector direction of diffusion of the first molecule within the critical zone is substantially parallel to an average vector direction of diffusion of the first molecule within the hydrophilic region; (c) at least one sensor, having a surface communicating with at least one hydrophilic region and sensitive to either of the second or third molecules, wherein the sensor is adapted to produce a signal indicative of the concentration of the second or third molecules in the hydrophilic region; and, (d) a control, responsive to the signal produced by the sensor, for comparing the signal to a reference to determine the concentration of said first molecule in the environment.