To a greater extent than in many areas of endeavor in the chemical sciences, successful chemical sensors require a high level of interdisciplinary collaboration and effort, along with an unusually close coupling between the ultimate application and the R&D process. The tremendous growth in chemical sensor R&D over the past ten years has been spurred by everything from fundamental advances in interfacial chemistry, to new microscale engineering technologies, to a demand for cleaner, more efficient, better-controlled industrial processes.