A system for forming a functionalized sensor for sensing a molecule of interest includes at least one single or multi-wall carbon nanotube having a first and a second electrode in contact therewith on a substrate; a third electrode including a decorating material on the substrate a predetermined distance from the at least one single or multi-wall carbon nanotube having a first and a second electrode in contact therewith, wherein the decorating material has a bonding affinity for bioreceptors that react with the molecule of interest; and wherein applying a voltage to the third electrode causes the decorating material to form nanoparticles of the decorating material on the at least one single or multi-wall carbon nanotube.