Abstract: The microneedle array includes a substrate having a central opening formed therethrough, and a plurality of microneedles positioned about a perimeter defining the central opening. At least one of the microneedles has a recess formed therein adjacent a tip thereof, and this recess is at least partially filled with a layer of active material. A sensor for detecting chemical analytes, biological analytes or the like may be constructed by providing two such microneedle arrays, with one serving as the working electrode and one serving as a reference electrode. The working electrode and the reference electrode may both be connected to a signal analyzer for detecting electrochemical signals. The working electrode and the reference electrode may be separate from one another or may be stacked together.