A metal-oxide-semiconductor (MOS) sensor has been designed, fabricated, and tested for use in the characterization of targeted alpha therapy pharmaceuticals. The sensor consists of a 16 $\times$ 16 array of 100-μ m square alpha particle sensitive cells and has been fabricated in house using a simple MOS process. A subset of those cells is functionalized for the attachment of chelators under investigation for new pharmaceuticals. To demonstrate the utility of this sensor as a characterization platform, cells functionalized with 1,4,7, 10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-DNA conjugates were used to chelate americium-241 from solution, and the alpha particle emissions over the surface of the integrated circuit (IC) measured. The IC was able to quantitatively determine the amount of alpha emitter present over each cell, allowing the chelator and chelating chemistry to be assessed. Without any optimization of the chelation chemistry, a 21% increase of emissions was detected on cells functionalized with DOTA.