One aspect of the invention provides an analyte monitor including a sensing volume, an analyte extraction area in contact with the sensing volume adapted to extract an analyte into the sensing volume, and an analyte sensor adapted to detect a concentration of analyte in the sensing volume. The sensing volume is defined by a first face, a second face opposite to the first face, and a thickness equal to the distance between the two faces. The surface area of the first face is about equal to the surface area of the second face and the extraction area is about equal to the surface area of the first and second face of the sensing volume. The analyte sensor includes a working electrode in contact with the sensing volume, the working electrode having a surface area at least as large as the analyte extraction area, and a second electrode in fluid communication with the sensing volume.